600D88282
THE POTENTIAL  EFFECTS OF GLOBAL  CLIMATE CHANGE
                ON THE  UNITED STATES
                          DRAFT

                   REPORT TO CONGRESS
                   Volume 2: National Studies



              Editors: Joel B. Smith and Dennis A. Tirpak




              United States Environmental Protection Agency

               Office of Policy, Planning, and Evaluation

                 Office of Research and Development



                         October 1988
                                                     .a i6?Q

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                            CHAPTER 8

                         WATER RESOURCES

FINDINGS

Many regions of the country are likely to experience changes in
water availability and water quality.  The frequency of droughts
and floods may change.  Under some scenarios, summer soil
moisture and water availability in middle latitudes may be
reduced due to temperature increase, a northward shift of the
rainbelt, and an earlier onset of winter snowbelt and spring
runoff.  Even under warm-wet scenarios, in many regions the
positive effect on supply of increased precipitation may be more
than offset by temperature increases that reduce supply by
evaporation and increase water demand.

o    A warmer and drier climate in some regions would decrease
     water supplies and increase water demand, especially demand
     for irrigation and electric power production.

o    Lower river flows resulting from drier conditions could
     negatively affect hydropower production, navigation, aquatic
     ecosystems, wildlife habitat, and recreation.

o    Lower stream flow and lower lake levels could cause power
     plants to locate in coastal areas to obtain a water source
     that is reliable and that may be used without violation of
     thermal restrictions.  This would have important
     implications for land use, transmission lines, and the costs
     of power.

o    Municipal and industrial water users may have greater
     incentives to purchase water rights in the West to ensure
     the reliability and quality of supply.

o    Because of earlier runoff and potentially higher
     evaporation, increased rainfall may not increase water
     availability in all regions.   However, flooding may
     increase.  Flood-prone regions may require structural
     modifications, new capital improvements, and modifications
     in operating rules for reservoirs.

Policy Implications

o    Changes in water availability and water quality and
     conflicts among water users are the major impacts of climate
     change on water resources, although the magnitude and
     distribution of hydrologic and water resource effects are
     still uncertain.   Responses could include the following:
                               8-1

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                                                  Water Resources
          build new storage capacity, provided that the
          structures show positive net benefits under a variety
          of possible climatic conditions;

          modify water system operations to improve performance
          under extreme conditions, to enhance recovery from
          extreme conditions, and to accept greater risk to low-
          valued uses in order to protect high-valued uses; and

          encourage a reduction in water demand and an increase
          in water use efficiency through conservation, water
          markets, water quality control, contingency planning,
          and coordinated uses of regional and interstate water
          resources, provided that such measures do not reduce
          the performance and recovery capabilities of supply
          systems.


CLIMATE, HYDROLOGY, AND WATER RESOURCES IN THE UNITED STATES

     The United States is endowed with a bountiful supply of
water, but the water is not always in the right place at the
right time or of the right quality.

     On the average, 4,200 billion gallons per day (bgd) of
precipitation fall on the lower 48 States.  However,  a large
portion of this water evaporates, leaving only 1,435 bgd to run
off into surface water and groundwater.

     Surface and groundwaters are managed by controlling and
diverting flows through impoundments and aqueducts; by
withdrawing water for such "off-stream" uses as irrigation and
municipal use; by regulating flows to maintain "in-stream" water
quality and such uses as navigation, hydropower, and recreation,
and by controlling flows under flood conditions to avoid loss of
life, damage to property, or inconvenience to the public.  Water
may be "withdrawn" and returned to the source more than once, or
"consumed" and not returned to the source.

     Control and use of water are costly.  Water supply for
municipal and industrial use represented a $108 billion national
investment in infrastructure in 1984 (National Council on Public
Works Improvement, 1988).  Government agencies and industries
spent $336 billion (in constant 1982 dollars) from 1972 to 1985
(Farber and Rutledge, 1987) on water pollution abatement and
control activities.  In other areas, excess water periodically
floods agricultural and urban areas, causing an average of $3
                               8-2

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Chapter 8
billion  (in constant 1984 dollars)  (National Council on Public
Works Improvement. 1988) per year in damages during the past
decade.

     Most water resource decisions  in the past have been based on
the assumption that the climate of  a region varies around a
stationary mean.  Even without climate change, the ability to use
water resources is greatly influenced by weather variability.  As
shown in Figure 8-1, weather controls hydrologic conditions
through precipitation (mean and frequency), runoff, snowmelt,
transpiration and evaporation, soil moisture, and the variability
of storms and drought.

Water Availability

     On a national scale, water supplies are adequate.  Largely
due to weather variability, only 675 bgd of the 1,435 bgd of
runoff water in the conterminous United States is considered
available in 95 out of 100 years for irrigation, municipal,
industrial, and other off-stream uses.  In 1985, freshwater
withdrawals for off-stream uses were 338 bgd.  Ninety-two bgd of
the withdrawals were consumed, mostly for irrigation.

     The supply of water from surface and groundwater sources for
soil moisture, in-stream uses, withdrawal, and consumption is
vulnerable to decreased precipitation.  Warmer temperatures would
increase the proportion of rain versus snow, would cause earlier
runoff of winter snowpacks, and would increase evaporation.
These effects would diminish water availability during the summer
and reduce water levels and flows.

     Although water availability exceeds withdrawals and
consumption, the water is not always in the right place at the
right time.  In some regions, the gap between demand for water
and available supply is narrow.  For example, average surface
water withdrawal exceeds average streamflow in the Great Basin,
Rio Grande, and Colorado River Basins.  In these water-short
basins, off-stream water uses often conflict with in-stream uses,
such as recreation and maintenance of environmental quality.
Degraded water quality further limits water availability in many
regions.

Water Uses

     The uses primarily affected by water availability
constraints are irrigation, thermoelectric power,  and industrial
and domestic water use.   Withdrawals and consumption of
freshwater by major offstream uses in 1985 are summarized in

                               8-3

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EVAPORATION AND TRANSPIRATION FROM
SURFACE WATER BODIES. UNO SURFACE
      ANO VEGETATION
        2.600 Dfld
                                1} ATMOSPHERIC MOISTURE -J. f
                                r«    40 000 twjd .    *';
                                '',   v
                                          TOTAL SURFACE
                                         AttO GROUND-WATER
                                          FLOW TO OCEANS
                                            1.300 bad  -
                                                            bgd=biliion gallons per day
Figure  8-1.
Hydrologic  cycle showing the gross  water budget of
the conterminous United States.
Source:   Langbein  et al.  (1949)  and Solley  et  al.  (1983).

                                       8-4

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Chapter 8
     As the largest and relatively least valuable use of
freshwater, irrigation accounts for 42% of freshwater withdrawals
and 82% of fresh water consumption in the United States.
Although irrigated land comprises about 10% of harvested cropland
acreage nationwide, it contributes 30% of the value of cropland
production.  Many of these crops are fruits, vegetables, and
specialty crops (U.S. Water Resources Council, 1978; Bajwa et
al., 1987).  The 17 Western states account for 85% of the
irrigated lands in the country (Bajwa et al., 1987).

     In contrast, thermoelectric powerplants withdraw almost as
much freshwater as irrigation but consume much less than
irrigation.  Although 131 bgd of freshwater are withdrawn to
produce 60% of the nation's electricity (Water Resources Council,
1978), only 4.35 bgd are actually consumed (Solley et al., 1988).

     Domestic uses account for 10% of total water withdrawn and
11% of consumption.  Over the past 20 years, domestic water use
has increased from 16 to 25 bgd owing to growth in the number of
households, with little change in usage per household (Solley et
al., 1988).

Water Quality

     Degraded water quality reduces the amount of water for human
use.  The Nation has made significant progress in cleaning up
water pollution since the enactment of the 1972 Clean Water Act.
However, some of the States reported that some persistent
pollution problems remain, especially contamination by toxic
pollutants and nonpoint source pollution (USEPA, 1987b).  Water
quality in the nation's rivers, lakes,  and streams depends in
part on water quantity.  Water supply is needed for dilution of
wastewaters that flow into surface and groundwater sources.
Freshwater inflows are needed .to repel saline waters in estuaries
and to regulate water temperatures in order to forestall changes
in the thermal stratification, water quality, aquatic biota, and
ecosystems of lakes, streams, and rivers.

Flood Control

     Major water management systems and structures, which are
designed to reduce hazards and damages from major floods, may
have the flexibility to adapt to modified flood conditions.  The
major concern with existing dams and levees is the consequence of
failure under extreme conditions.

     For instance,  an increased probability of great floods,
whether due to urbanization of upstream watersheds or climate

                               8-5

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Chapter 8
change, would cause dams with inadequate spillways to fail.  Some
major structures may be currently vulnerable to a "probable
maximum flood"  (National Research Council, 1986).  Smaller
structures, such as urban drainage culverts and sewers and local
flood protection projects, are currently more susceptible to
floods and are  in poorer condition than large structures
(National Council on Public Works Improvement, 1988).
REGIONAL IMPACTS OF CLIMATE CHANGE

     The EPA regional studies reported in this document use
scenarios generated from up to four GCMs as their starting points
(see Chapter 3) and match them with regional water resource
models.  This section combines the results from this report's EPA
studies on California, the Great Plains, the Great Lakes, and the
Southeast with previous studies of the impacts of climate change
on these and other regions.  The EPA studies are listed in Table
8-1.

     Climate impacts may be greatest on regions already stressed:
where water demand is great and supply is short, where water
quality has deteriorated, or where periodic excess supply floods
agricultural and urban lands.  Table 8-2 summarizes the current
status of water supply by major river basin region.  The regions
are delineated in Figure 8-3.

West

     The arid and semiarid river basins west of the Mississippi
show up as problem areas in all four of the U.S. Water Resources
Council's water quantity and quality maps.  Total water use
exceeds average streamflow in 24 of 53 western water resource
regions (U.S. Water Resources Council, 1978).   The majority of
the West's water withdrawals go to irrigation.  Surface and
groundwater quality in the West have deteriorated due to low
flow, salts concentrated by irrigation, and pesticide use.  The
West also depends upon nonrenewable groundwater supplies for
irrigation (Solley et al., 1988).

     Climate change may exacerbate water shortage and quality
problems in the West.  Some GCM scenarios predict midsummer
drought and heat, less groundwater recharge,  and less groundwater
and surface water available for irrigation in the middle
latitudes of the country.  The sensitivity analyses conducted by
Stockton and Boggess (1979) indicated that the warmer and drier
                               8-7

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                                                  Water Resources
                Table  8-1.  Water Resource Studies
 Region                         Study
California
          Interpretation of Hydrologic Effects of Climate Change
          in the Sacramento-San Joaauin River Basin. California -
          Lettenmaier, University of Washington.

          Methods for Evaluating the Potential Impact of Global
          Climate Change - Sheer and Randall, Water Resources
          Management, Inc.

          The Impacts of Climate Change on the Salinity of San
          Francisco Bay - Williams, Philip Williams & Associates
Great Lakes
          Effects of Climate Changes on the Laurentian Great
          Lakes Levels - Croley, Great Lakes Environment Research
          Lab.

          Impact of Global Warming on Great Lakes Ice Cycles -
          Assel, Great Lakes Environment Research Lab.

          The Effects of Climate Warming on Lake Erie Water
          Quality - Blumberg and DiToro, HydroQual, Inc.

          Potential Climatic Changes to the Lake Michigan Thermal
          Structure - McCormick, Great Lakes Environment Research
          Lab.
Great Plains
Southeast
          Effects of Proiected C0?  -  Induced  Climate  Changes on
          Irrigation Water Reguirements in the Great Plain States
          - Allen and Gichuki, Utah State University.
          Potential Impacts of Climatic Change on the Tennessee
          Valley Authority Reservoir System - Miller and Brock,
          Tennessee Valley Authority.
                               8-8

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Chapter 8
        o Impacts on Runoff in the Upper Chattahoochee River
          Basin - Hains, C.F.  Hydrologist,  Inc.

        o Methods for Evaluating the Potential Impact of Global
          Climate Change - Sheer and Randall,  Water Resources
          Management,  Inc.
                               8-9

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                                                  Water Resources
scenarios may have the greatest impacts in arid western river
basins (Rio Grande, Colorado, Missouri, California)  by increasing
water shortages.

     Revelle and Waggoner (1983) showed that warmer air
temperatures and slight decreases in precipitation could severely
reduce both the quantity and quality of western water resources.
Water shortages and associated conflicts between in-stream and
off-stream uses, between agricultural and urban/industrial water
uses, and between flood control and other water uses of
reservoirs may be expected.   Hydropower output also may decline
due to lower riverflow.

Pacific Northwest

     Climate change may alter the timing and volume of
precipitation, increasing the risk of flooding, changing
reservoir management practices, and affecting the output and
reliability of hydroelectric power production and the
availability of water for irrigation.  Butcher et al. (1986)
found that competition for water for irrigation, hydropower, and
fisheries habitats is increasing in the Pacific Northwest.

California

     The diversion of water from water-rich northern parts of the
State and from the Colorado River to southern California via
Federal and State systems of dams, aqueducts, and pumping
stations has transformed California into the nation's leading
agricultural state and has made possible the urbanization of
southern California.  Irrigation accounted for 83% of the
total value of agricultural output in the State in 1982 (Bajwa et
al., 1987).  Because of this high economic dependence on water in
an arid area, southern California is vulnerable to droughts and
altered runoff patterns that may be caused by climate change.

     Total annual runoff from the mountains surrounding the
Central Valley is estimated to increase slightly under GCM
scenarios, but runoff in the late spring and summer may be much
less than today because of higher temperatures.  The volume of
water from the State Water Project may decrease by 7-16% (see
Chapter IV).  Current reservoirs do not have the capacity to
increase storage of winter runoff and at the same time retain
flood control capabilities.   In addition, freshwater requirements
to repel saline water near the major freshwater pumping
facilities in the upper Sacramento-San Joaquin River Delta may
have to be doubled under sea level rise, scenarios, further
reducing water available to southern California.

                               8-12

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f
       Chapter 8
     Decreases in water availability due to climate change may
also cut hydroelectric power produced in California.  In the
1976-77 drought, hydroelectric production in northern California
dropped to less than 50% of normal, a deficiency relieved by
importing surplus power from the Pacific Northwest and by burning
additional fossil fuels at an approximate cost of a half billion
dollars (Gleick, 1988).

Colorado, Rio Grande, and Great Basin River Basins

     Total consumption is more than 40% of renewable supply in
these river basins.  The Colorado River Basin has huge reservoir
storage, but demand exceeds supply in the lower half of the
basin.

     Ordinarily all of the Colorado River's water is consumed
before it reaches the Gulf of California in Mexico.  The Colorado
River Compact of 1922, the 1963 Supreme Court decision in Arizona
v. California. 1944 and 1973 treaties with Mexico, and other
agreements define the allocation of Colorado River water to seven
States and Mexico (Dracup, 1977).   Some studies show that the
Upper Colorado region will use all of its allocation by the year
2000, curtailing water available to lower Colorado and California
(Kneese and Bonem, 1986).  Climate change may further reduce the
availability of water in these basins.  Stockton and Boggess's
(1979) model of a 2°C temperature increase and a 10%
precipitation decrease cuts water supply in the upper Colorado by
40% and in the Rio Grande by 76%.   Flaschka (1984) found that a
decrease in precipitation of 25% combined with a temperature
increase of 2°C could decrease annual runoff by 50% in the Great
Basin.

Great Plains

     The southern Great Plains States of Kansas, Nebraska,
Oklahoma,  and Texas produce almost 40% of the nation's wheat, 15%
of its corn, and 50% of its fattened cattle (see Chapter 10).
The region heavily depends on groundwater mining (when pumping
exceeds aquifer recharge)  for irrigation.  The region was hard
hit during the "dust bowl" years of the 1930s and suffered from
severe drought in 1988 (see Chapter 10).

     Because of greater stability in irrigated yields relative to
dryland yields, a rise in commodity prices will make expansion of
irrigated production economically feasible.   Thus, while total
agricultural acreage is expected to decrease,  irrigated acreage
and groundwater mining are expected to increase in the southern
Great Plains (Chapter 10).  Greater demand may be placed on the

                              8-13

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                                                  Water Resources
Ogallala Aquifer, which underlies much of the region, causing
further groundwater mining of the aquifer.

     Water quality appears to be vulnerable to deterioration
because of increased use of agricultural pesticides as a response
to climate change in surface runoff and erosion and decreased
water flows.

Great Lakes

     According to the GCMs, higher temperatures may overwhelm any
increase in precipitation and may evaporate lakes to below the
lowest levels on record.  The winter ice cover would be reduced
but would still be present, especially in shallow areas and
northern lakes.  Navigation depths, recreation, erosion (e.g.,
shrinking Chicago shoreline), hydropower output, and water
quality all would be affected (see Chapter 5).

Mississippi River

     The Mississippi River has historically been affected by both
spring floods and drought.  In 1988, low flows due to drought
received national attention.  Low flows disrupt navigation,
degrade the drinking water for southern Louisiana cities,  and
reduce the inflow of water to the vast Mississippi Delta.

Northeast

     During periodic droughts in the Northeast, such as in
1962-65 and 1980-81, in-stream flow regulations ration water and
threaten shutdowns of electrical powerplants (U.S. Army Corps of
Engineers, 1977; Schwartz, 1977; Kaplan et al., 1981).  Although
the Northeast is humid, cities and powerplants demand large
amounts of water at localized points in a watershed,
necessitating storage and interbasin transfers.  No new major
storage has been built in the Northeast during the past 20 years,
except the Bloomington Dam on the Potomac River.  Water supply in
lower New England, New York, and Pennsylvania,  and power
production in the Northeast remain vulnerable to the droughts
that may occur, according to some climate change scenarios
(Schwartz, 1977; Kaplan et al.,  1981; and see Chapter 15).

Southeast

     The drought of recent years is increasing demands for
irrigation in the Southeast and is prompting farmers to consider
shifting crops.  However, studies for this report are unclear on
whether the Southeast may become wetter or dryer.

                              8-14
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Chapter 8
     Most reservoirs in the area have sufficient capacity to
retain flood surges and maintain navigation, hydropower, water
supply, and in-stream uses (e.g. dilution, wildlife) in both wet
and dry climate change scenarios (see Chapter 6). However, dryer
conditions would pose conflicts between recreational uses (which
would be hurt by changes in reservoir levels) and all other
in-stream and off-stream uses.

     Finally, a possible decline in the flow of freshwater to the
Gulf coast and estuaries would change the estuarine ecology.
NATIONAL IMPACTS OF CLIMATE CHANGE ON WATER RESOURCES

     Climate change and regional models do not yet provide
reliable data to indicate the net national or regional costs and
benefits of climate change.  Accurate quantitative predictions,
such as dollar losses or numbers of people affected by climate
change, cannot be made.  With current information, however, we
can indicate possible directions of impacts and sectors affected.
For example, water shortages may stifle economic growth, impose
hardships on existing users, and result in transfers of water to
uses with the highest value.

     A major national impact of climate change on water resources
may be to increase conflicts between regional water uses.
Decreased water availability and increased water demands may
intensify conflicts in the following areas:

     o between in-stream and off-stream uses;

     o among off-stream uses, such as agriculture, domestic use,
       and thermoelectric power;

     o between water supply and flood control in the West;

     o between all uses and recreation in the Southeast; and

     o between thermoelectric power production and in-stream
       uses, especially in the East.

     Increased precipitation due to climate change may decrease
conflicts in some areas, but only after management infrastructure
is modified to account for large maximum floods.

     The potential effects of climate change on supply and demand
must be compared to existing water supply and demand and to
projections for supply and demand without climate change.  Figure

                              8-15

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                                                  Water Resources
8-4 outlines the national impacts of climate change on water
supply and demand.  Table 8-3 highlights the vulnerability of
major water uses to climate change impacts by region.  The
following sections outline the potential impacts of climate
change on traditional categories of off-stream and in-stream
water uses.

Off-Stream Uses of Water Resources

     Water supply and use have changed significantly during the
past decade.  For the first time since 1950, when the United
States Geological Survey began recording water withdrawals, there
was a 10% national drop in total fresh and saline water
withdrawals from 1980 to 1985 (443 billion gallons to 399 billion
gallons) (Solley et al., 1988).   Increased conservation and water
recycling in agriculture, industry, and energy production, slower
growth in energy demand, and decline in availability of new water
supply reduced or tempered water use in all sectors  (Solley et
al., 1988).  Withdrawals declined by 7% in irrigation, by 33% in
industry, and by 13% in thermoelectric power during the period.
Of the major users, only municipal/domestic water supply
increased (by 7%).

Irrigation

     Water-short western States are intensively exploring avenues
for minimizing water requirements.  Because of depleted
groundwater supplies, the rising cost of obtaining groundwater,
and high costs and limited sites for new surface water
developments, irrigated agriculture is no longer expanding or is
declining in some areas of the West (Solley et al., 1988).
Groundwater pumping for irrigation has already started to decline
in the southern Great Plains States and in Arizona, although the
impacts on production have been mitigated by the adoption of more
efficient irrigation systems and switching to crops offering
higher returns to water (Frederick and Kneese, 1988).

     In contrast, supplemental irrigation in the East is on the
rise (Viessman and DeMoncada, 1980).  But overall, in the absence
of climate change, agricultural water use trends will be
characterized by only moderate increases or, in some cases,
decreases in the next 20 years (Viessman and DeMoncada, 1980).
Most analysts predict greater agricultural output per unit of
water input.

     Climate change may severely affect agriculture.  Summer
drought in the West and Midwest and earlier runoff are likely to
                               8-16

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                                    Climate Change
                    I
           Temperature Increase in
                All Regions
                                          1
                               Regional Weather Variability
        I
 Increased Demand
 for Air conditioning
Greater evapotranspiration
    Soil moisture loss
    Earlier snowmelt
                               I
Less precipitation
 Less runoff and
   streamflow
More precipitation
 More runoff and
   streamflow
                                             Reduced water supply
                                                 in hotter, drier
                                                   regions
                                               Increased flooding
                                                in hotter, wetter
                                                    regions
Increased demand for
  cooling water for
   electric power
    production
               Increased demand
                 for irrigation
                        Increased demand
                            for flood
                            control
Increased surface
water withdrawls
1


1
Adverse effects
on water
quality

Increased water
consumption and
groundwater
mining



Conflicts between
off-stream and
in-stream uses



1
Conflicts between
irrigation and
municipal/ industrial
uses
                                                                      Conflicts between
                                                                       flood control and
                                                                        all other uses
                    1
               Storage/supply
              policy alternatives
                                    Nonstructural/demand
                                      policy alternatives
   Figure  8-4.
    National  impacts  of  climate change  on  water
    supply  and  demand.
                                          8-17

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-------
Chapter 8
change agricultural practices, cause dislocations in entire
regions, and increase demands for irrigation.  And even if the
Southeast is wetter, higher temperatures may increase irrigation
demand there (see Chapter 6).

Thermoelectric Power Generation

     Future demand for water for power production will depend
upon energy demand and Federal and State regulations governing
in-stream water guality and thermal pollution.  Due to minimum
in-stream flow and maximum river temperature requirements of
environmental regulations and the large amount of installed
capacity along eastern rivers, freshwater withdrawals by steam
electric powerplants have decreased, and siting of plants in
coastal areas has increased.  Thirty percent of installed
capacity used saline surface water in coastal areas in 1985
(Solley et al., 1988).  In addition, thermal regulations have
effected a shift in new construction of cooling systems, from
once-through to evaporative cooling (Miller, 1988).  With
once-through cooling, waste heat is discharged directly into the
waste stream.  Although evaporative cooling with towers and ponds
alleviates thermal pollution, it increases water consumption.

     During droughts, federal and state regulations protecting
in-stream uses and limiting thermal discharges may constrain
withdrawals for powerplant cooling (Kaplan et al., 1981; Miller,
1988).  In addition, powerplant water needs on some eastern
rivers are so large that during low-flow conditions, insufficient
water is available to dissipate heat (Kaplan et al., 1981).

     Demand for power may increase as warmer temperatures raise
air-conditioning use (see Chapter 16).   If streamflows are
reduced as a result of climate change,  powerplants using
once-through cooling could be adversely affected  (Miller, 1988).
Increased demand for power may reinforce existing trends in
powerplant design toward evaporative cooling and powerplant
siting toward coastal sites.  Purchases of water rights from
other users by electric utilities in the West to meet cooling
needs may increase.  With less water available, low-flow
conditions may interrupt power production and may increase power
production costs and consumer electricity prices.

Industry

     Since 1954, most major self-supplied industries steadily
used less and less water per unit of production (Solley et al.,
1988).  This decline was partly due to  efficiencies achieved by
complying with federal and state water  pollution legislation that

                               8-19

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                                                  Water Resources
restricts the discharge of untreated water.  The trend toward
more efficient industrial water uses is likely to continue.
Industrial production across the country may be constrained by
water quality if flow drops, and production in the West may be
constrained by water supply curtailment.

Domestic Water Uses

     Most municipal water supply systems are designed to provide
reliable water at all times (safe yield).   However, urban growth
depends upon developed water supply which may be rapidly
exhausted in some areas.  In the Southeast and parts of the West,
a large percentage of municipal water supply comes from
groundwater (U.S. Water Resources Council, 1978; Solley et al.,
1988).   These regions have few groundwater recharge programs, so
drought caused by climate change may decrease groundwater quality
and quantity (see Chapters 6 and 7).

     As relatively high-valued users of water, municipalities in
the West are purchasing water rights to ensure adequate water
supplies for urban growth.  In the East, Midwest, and Southeast,
municipalities may be able to increase safe yield by repairing
and replacing existing leaking water delivery systems and by
consolidating fragmented water supply districts.

In-stream Uses and Water Quality

     The value of in-stream uses has risen relative to off-stream
uses.  Navigation and hydropower have retained their importance,
as the values of wastewater dilution, ambient water quality, fish
and wildlife habitats, and recreation have risen.  Higher values
placed on in-stream uses have made diversion of water for such
uses as agriculture in the West and for powerplant cooling, more
difficult.  In general, climate change may put pressures on in-
stream water uses and may degrade water quality.

Water Quality

     The Federal Clean Water Act and its amendments ushered in a
new era of water pollution control.  Massive expenditures have
decreased the amount of "conventional" water pollutants entering
national water supplies.  Total public and private, point and
non-point, capital and operating water pollution abatement and
control expenditures from 1972 to 1985 totaled $336 billion in
1982 dollars (Farber and Rutledge, 1987).   Nevertheless, serious
water quality problems remain.

     One-third of municipal sewage treatment plants have yet to

                               8-20

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Chapter 8
comply with the provisions of the Clean Water Act  (USEPA, 1987a).
federal and state regulations governing previously unregulated
toxic and hazardous water pollutants has just begun.  And in the
West, irrigation has caused the salinity levels in the water and
soils in several river basins (the lower Colorado, the Rio
Grande, and the San Joaquin) to rise so high that the viability
of irrigation is being threatened (Frederick and Kneese, 1988).

     With climate change, less freshwater may be available in
some cases for diluting wastewater and recharging aquifers.
Furthermore, increased thermal stratification accompanied by
enhanced algal production may degrade the water quality of many
lakes.  Finally, the combination of declining freshwater
availability and rising sea level would move salt wedges up
estuaries, changing estuarine ecology and threatening municipal
and industrial water supplies on the other hand, increased flows
could allow for greater dilution of pollutants.

Navigation

     Lower riverflow and lake levels would impede navigation.
Systems that are particularly vulnerable are those with
unregulated flow and high traffic, such as the lower Mississippi
River and the Great Lakes.

Flood Control

     The expected changes in the timing and magnitude of snowmelt
and precipitation nationwide may restrict the flood control and
multiple use capabilities of existing reservoirs and other
structures.  For example, drawing down the levels of reservoirs
to contain floodwaters from anticipated increases in
precipitation or earlier snowmelt may curtail water availability
for other uses.

     Because of the buffering and redundancy designed into large
structures, major Federal flood control projects may be able to
contain or mitigate the impacts of more frequent or severe
floods. In addition, the majority of dams that provide
substantial flood storage are in good condition. The National Dam
Safety Inventory shows that the overall condition of the U.S.
Army Corps of Engineers' more than 300 flood control reservoirs
is sound (National Council on Public Works Improvement, 1988).

     On the other hand, one-third of the non-Federal flood
control dams inspected under the national non-Federal dam program
were found to be unsafe, mostly due to inadequate spillways
(National Council on Public Works Improvement,  1988).  (Spillways

                              8-21

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                                                  Water Resources
are designed to prevent dam failure through overtopping.)  These
non-federal, smaller, mostly urban, flood control and stormwater
structures may be more likely to have their capacity exceeded.

     Some large dams may become susceptible to failure if storm
intensity increases.  The spillways of many large dams are
designed to pass a "probable maximum flood" (an extreme flood
event much greater than the 100-year flood).   However,
urbanization upstream from many dams is resulting in increased
impervious surface (such as pavement) and increased peak runoff,
and the probabilities of great floods, although remote, may
increase due to climate change.

Hydropower

     Because of the decline in water availability that could
result from climate change, hydropower output and reliability
could decline in the West and the Great Lakes.  The Southeast
could be facing the same problems unless it sacrificed or altered
reservoir storage of streamflow increases in regions such as the
Southeast hydropower production would increase also.

Recreation

     Warmer and dryer conditions in the Southeast may increase
the conflict between water uses, especially over reservoir
releases and levels in the Tennessee Valley Authority region and
the Lake Lanier, Georgia, systems.  The conflicting uses may
include releases for navigation, in-stream uses, urban water
supply, groundwater recharge, hydropower and recreation (see
Chapter 6).
NATIONAL POLICY IMPLICATIONS

     Decreases in water availability,  increased risk of flood
damages, and the ensuing conflicts between water users competing
for an increasingly scarce or difficult to manage resource are
the major water resource issues raised by the possible, impacts of
a global warming trend.  Some regions  may restrict water use for
lower value uses or may facilitate transfer of their water rights
to higher value uses. How will we manage the transition to the
new water resource regimes possible under climate change?

     Current policy responses are complicated by the uncertainty
attached to climate change forecasts.   To be more helpful, the
forecasts should be specific by area and should be accurate over
the design-life of water resource structures.  For example, they

                               8-22

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Chapter 8
may depend in part on whether policymakers believe that the
impacts will be felt as soon as 20 years from now or will occur
gradually over 100 years.  Forecasts of rapid climate changes may
argue for measures to quickly prevent and avert climate change
impacts; forecasts of gradual change may argue for policies that
adapt and adjust to the change over time.

     The implications of uncertainty include the following:

     o    Do not invest in irreversible, inflexible, large-scale,
          and high-cost measures.

     o    Design, modify, and rehabilitate structures and
          operating procedures that will provide robust and
          resilient water resource systems under different
          climate change scenarios.

     o    Implement a wide variety of measures for reducing
          demand, as long as they do not reduce the robustness
          and resilience of the systems.

     Policy approaches to water resources may be grouped under
supply (or structural) approaches and demand (or nonstructural)
approaches. For example, water shortages may be addressed either
by increasing developed "supply (storage capacity) or decreasing
water consumption and improving water quality.

     Many or most of the policy approaches listed below have been
recommended by water resource experts for 20 years.  The
potential impacts of climate change are an even greater impetus
for implementing these policies.

Supply and Structural Policy Approaches

Developing Surface Water Structures

     Surface water structures increase developed or available
water supply or prevent flooding.  These structures include dams,
reservoirs, levees, and aqueducts.

     Because of high costs of construction,  adverse impacts on
the environment and in-stream uses, limited sites available for
new structures, and opposition by citizen groups, the trend
during the past decade has been away from large excess-capacity,
capital-intensive projects.   Recent Federal  financing for large
structures has largely been limited to modifying, maintaining,
and rehabilitating existing structures (Bureau of Reclamation,
1987) .   Only the Central Utah Project and the Central Arizona

                              8-23

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                                                  Water Resources
Project have gone forward in recent years.  Largely because of
public opposition to new dams, only one major project in the
Northeast has been completed in past 20 years — the Bloomington
Dam on the Potomac River.  California citizens in 1982 voted down
funds for the proposed Peripheral Canal that would increase
diversion of water from north to south in the State.  The trend
toward local/state and away from federally financed projects has
reduced funds available for large projects (National Council on
Public Works Improvement, 1988).

     These current trends in water resources management may be
reevaluated in light of possible new demands for developed water
supply under warm-dry climate change scenarios.  Climate change
may create pressure to build the Animas-La Plata and Narrows
Projects proposed for Colorado, the Garrison Diversion in North
Dakota, the Peripheral Canal in California, and structures to
divert water from northern New England to southeastern
Massachusetts.

Including Climate Change in Structural Design

     Climate change should be a consideration in design and risk
analysis for repair and replacement of existing projects and for
constructing new projects (Hanchey et al., 1986).  Current
engineering and management approaches design for the mean,
variability, and extremes of historical record.  Large systems
have substantial redundancy and robustness that enable them
technologically and institutionally to adapt to large stresses
(Matalas and Fiering, 1977).  However, future climate may change
hydrologic conditions from those on which the management of
several major water systems is based.

     In some cases, design includes both structural and
nonstructural measures.  Society may not be able to afford to
build costly fail-safe water supply or flood control projects.
For example, the design of Army Corps of Engineers' projects is
increasingly becoming "safe-fail."  This is a strategy of
designing flood protection,  for example, for less than the
extreme event of record but for the 20- to 50-year flood, and
then complementing the structural measure with emergency
management plans that mitigate the damages (Hanchey et al.,
1986).

Optimizing Water Resource Systems

     Operational strategies for large-scale water systems and
watersheds can have an enormous influence on the overall
performance and resilience of the system and may provide

                               8-24

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Chapter 8
additional water supplies to mitigate the impacts of climate
change.  Management practices may allow for substantial operating
flexibility concerning releases of stored water. However, current
design and management practices rely on historical data that may
be superseded by new hydrologic averages and extremes.

     Water yields may be substantially increased by operating
existing facilities and surface and groundwater supplies as
systems, rather than as independent projects (Sheer, 1985).  For
example, the Federal Bureau of Reclamation (1987) is adopting
operational, management, or physical changes to gain more output
from the same resources.  Protection of groundwater recharge
areas and methods for the conjunctive use of ground and surface
waters are being implemented nationwide by water management
agencies (Tripp and Jaffe, 1979; U.S. Water Resources Council,
1980).

     Watershed management practices also affect water supply.
For example, water yields can be significantly affected by timber
harvest practices.  Approximately 70-80% of water yield in the
West is the result of snowmelt in high-elevation forests, much of
which is under public jurisdiction (Troendle,  1983).

Demand Management and Nonstructural Policy Approaches

     The limitations of supply and structural  solutions to the
nation's water problems may argue that greater attention should
be given to demand management to resolve long-term water resource
problems and to mitigate the potential adverse impacts of climate
change.  In the past, water was considered too essential a
resource or too insensitive to price for its use to be allocated
by market forces during shortages.  Policy took the form of
direct controls and appeals to conserve (Hrezo et al., 1986).  In
recent years, greater attention has been given to institutional,
legal, and market policies to allocate and regulate limited water
supplies among competing uses and to promote water conservation.

Reducing Irrigation Use

     Relatively small reductions in the percentage of irrigation
demand can make large amounts of water available for higher value
urban and industrial uses.  For instance,  nearly 83% of
withdrawals and 90% of the consumptive use of  western water is
for irrigation.  Consequently, a 10% reduction in irrigation use
may save 20 million acre-feet (maf) in water withdrawn and 10 maf
in water consumed annually.  This would save an amount
approximately equal to the average annual  flow of the Upper
Colorado River Basin and would double the  water available for

                              8-25

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                                                  Water Resources
municipal and industrial uses in the West (Frederick, 1986).

     Estimates of water savings through improved efficiencies in
irrigation management range between 20 and 50 % (Viessman and
DeMoncada, 1980).  Due in part to decreased availability,
increased costs of pumping groundwater, and opportunities to
market water rights to higher value users, irrigation declined 6
% from 1980 to 1985 (Solley et al., 1988).

     Inexpensive water was a key factor in the settlement of the
West and the expansion of agriculture (Frederick,  1986).   The
Bureau of Reclamation was established early in this century to
promote the development of irrigation in the West.  The Bureau
provides irrigation for about 11 million acres, more than
one-fifth of the total irrigated acreage.  In 1975, it supplied
28.1 maf of water, 93% of which was used for irrigation  (Bureau
of Reclamation, 1976).  Since the Bureau accounts for nearly
one-third of all surface water deliveries and about one-fifth of
total water deliveries in the 17 Western States, using this water
more efficiently could be very important.

     In the past, demand for Bureau water was not based on the
real cost of the water, because more than 90% of the Bureau's
irrigation projects have been subsidized, and payments on some
projects no longer even pay for operation and maintenance
(Frederick and Hansen, 1982).  Irrigators fortunate enough to
receive such inexpensive water may have little or no incentive to
conserve.  However, the Bureau's more recently stated objectives
include revising their water marketing policy, promoting
conservation, and pricing water to reflect its real cost (Bureau
of Reclamation, 1987).

     The 1985 Food Security Act and programs managed by the U.S.
Department of Agriculture encourage water conservation and
maintenance of water guality (Rosenberg, 1988).  USDA programs
focus on conserving soil and water, setting aside crops,  and
retiring marginal lands.

Municipal and Industrial Water Use

     Municipalities throughout the country are finding it
difficult and expensive to augment their supplies to meet the
demands of population and economic growth.  Traditional average-
cost pricing designed to provide adequate service to customers
and returns to water companies is being reevaluated
(Congressional Budget Office, 1987).  Average-cost pricing and
declining-block rates tend to cause overinvestment in system
capacity and overuse of existing capacity.  Marginal-cost pricing

                               8-26

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Chapter 8
or progressive-rate structures (charging for the actual amount of
water used) can reduce domestic and industrial water consumption
because water use is sensitive to price (Gibbons, 1986) .

Water Markets and Transfers in the West

     It is unlikely that the Federal Government will subsidize
many more large irrigation projects.  Instead, conservation
incentives, prices, and water markets are becoming important
management tools to balance water demand with supplies.  Evidence
shows that many water uses, including irrigation, are sensitive
to price (Gibbons, 1986).   However, while irrigators in may cases
can adjust to higher prices and to water market opportunities,
incentives for abandoning traditional water-intensive practices
are still lacking for many areas in the West.

     The "first in time, first in right" appropriation doctrine,
which favors the longest standing water rights, governs much of
the West's surface water and some groundwater.  It encourages
economic development by guaranteeing users a secure supply of
water.  This doctrine was potentially an important step for
creating clear, transferable property rights to water — a
precondition for effective operation of water markets.  The
potential for water transfers to the highest value users has not
yet been fully realized because the nature and transferability of
the rights are obscured by legal and administrative factors
(Trelease,  1977; Frederick, 1986; Saliba et al., 1987).
Following are some examples.

     o    Rather than grant absolute ownership, States with prior
          appropriation rules grant rights to use water for
          beneficial purposes.  Water rights not put to
          beneficial use may be forfeited.  This encourages a
          use-it-or-lose-it attitude.

     o    Federal and Native American water rights remain
          unquantified in some areas, such as the Colorado River
          Basin.

     o    The U.S. Department of the Interior's Bureau of
          Reclamation supplies 30% of the irrigation water in the
          West.  There are few incentives to conserve this water,
          because the Bureau's long-term,  interest-free repayment
          contracts keep the price low and limit opportunities to
          transfer the water to users willing to pay more.
                              8-27

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                                                  Water Resources
     o    Because of imperfect competition, third-party effects,
          uncertainty over administrative rules, and equity
          considerations, water market prices may not
          appropriately measure water values according to
          economic efficiency criteria (Gibbons, 1986; Saliba et
          al., 1987).

     o    It is possible to control groundwater withdrawals, but
          for a number of reasons it is difficult to establish
          market mechanisms for groundwater allocation.  Because
          all groundwater users essentially draw from a shared
          pool, groundwater resources are treated as  "common
          property."  As a result, property rights are difficult
          to define, third- party impacts of transfers of
          groundwater rights are significant, and interstate
          agreements concerning allocation of interstate aquifer
          water are difficult to attain (Emel, 1987) .

     Despite the obstacles, transfer of water rights among users
— especially from irrigators to municipalities and power
companies seeking water for urban expansion and electricity
production — is becoming common in many Western States (Wahl and
Osterhoudt, 1985; Frederick, 1986).  Methods include negotiated
purchases, short-term exchanges during droughts, and water banks
and markets (Wahl and Osterhoudt, 1985; Saliba et al., 1987; Wahl
and Davis, 1986).

     Legislation in many Western States has facilitated water
transfers (Frederick, 1986; Frederick and Kneese, 1988) .
Arizona's new water law facilitates the purchase of land with
water rights and the use of that water for urban development.
Strict technical standards imposing conservation on municipal and
industrial water uses, such as watering golf courses with
wastewater, are also part of Arizona's laws (Saliba et al.,
1987).  California has applied the public trust doctrine to
modify existing permits to require flow releases to protect the
Sacramento-San Joaquin Delta from saltwater intrusion (Tarlock,
1987).  Montana is increasingly basing water management plans on
its in-stream flow requirements and is exploring ways to have
these requirements for all future beneficial in-stream uses count
as a bona fide use of the Missouri River in order to slow the
rate of growth of diversion of water for off-stream uses
(Tarlock, 1987).  The Supreme Court decided in Colorado v. New
Mexico (456 U.S. 176 (1982)) that equitable apportionment may be
used to override prior appropriation priorities in cases of major
flow reductions.  The Supreme Court specifically mentioned
climatic conditions in ruling that prior appropriation systems
                              8-28

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f
        Chapter 8
would otherwise protect arguably wasteful and inefficient uses of
water at the expense of other uses.


     Frederick and Kneese (1988) caution that water transfers
occur gradually and are not likely to affect more than a small
percentage of agricultural water rights for the foreseeable
future.  However, legal and institutional changes facilitating
water markets and demand for water by high-value users may be
accelerated under the stress of climate change (Trelease, 1977).

Interstate and Regional Compacts and Commissions

     River basin and aquifer boundaries in many cases traverse or
underlie portions of several States.  Regional and interstate
cooperation to manage water resources has a long tradition in
some U.S. river basins.  Implementing the agreements  required
for regional compacts and operating procedures and sharing of
water supplies may require substantial and lengthy negotiations.
However, the cost savings also can be substantial (Sheer, 1985).

     Several interstate water authorities have significant
allocation authority.  For example, the Delaware River Basin
Commission allocates water to users in the Delaware Basin and
transfers it to New York City.  It does so by the authority of a
1954 Supreme Court ruling (347 U.S. 995) and Federal legislation
establishing the Commission in 1961 and granting it regulatory,
licensing, and project construction powers.  Similarly, water
authorities in the Washington, D.C., metropolitan area operate
Potomac River water supply projects as integrated systems under a
1982 agreement.  Both the Delaware and Potomac regional compacts
include provisions for drought allocations.  (See Harkness et
al., 1985, for management actions taken by the Delaware River
Basin Commission during a 1984-85 drought.)  Sheer (1985)
estimated that coordinated water authority activities in the
Potomac River Basin eliminated the need for new reservoirs,
saving from $200 million to $1 billion.  In the West, the most
prominent interstate agreement is the Colorado River Compact,
which divides river water allocations among seven Western States
and Mexico (see Weatherford and Brown, 1986).

     Numerous opportunities exist around the country for
interstate, intrabasin, and interbasin coordination of water
deliveries.  In the East, consolidation of or coordination among
fragmented urban water supply authorities can achieve economies
of scale in water delivery,  decrease the risk of shortage in any
one subsystem within a region, and provide drought management
procedures (Sheer, 1985).

                               8-29

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                                                  Water Resources
Drought Management Policies

     Integrating drought planning into water resource management
may assume greater priority if climate change causes water
shortages. The Model Water Use Act (Hrezo et al., 1986) advocates
that states or water supply authorities integrate drought
management and advance planning into their policies by
designating a governmental authority for drought response and
adopting mechanisms for automatically implementing and enforcing
water use restrictions.  In 1986, only seven States had
comprehensive management plans for water shortages (Hrezo et al.,
1986).   Most States rely on general water rights, emergency
responses, and litigation to allocate water during shortages.

Water Quality

     Federal and State legislation and regulations for control of
in-stream water quality have had a dramatic effect on reducing
conventional water pollutants since the enactment of the 1972
Clean Water Act.  However, some persistent water quality problems
remain to be addressed (see USEPA, 1987b).   In some cases, where
river and lake levels are lower, more stringent controls on point
and nonpoint sources may be required to meet water quality
standards.

     Many States have adopted measures to protect in-stream water
uses.  These include reserving flows or granting rights for
particular in-stream uses and directing agencies to review
impacts before granting new rights (U.S. Water Resources Council,
1980; Frederick and Kneese, 1988).  Regulations limiting water
use may have to be modified under some climate change scenarios
that forecast increased incidence of low flows in some regions.

Policies for Floodplains

     The National Flood Insurance Program was enacted in 1968,
with major amendments in 1973.  The program provides subsidized
flood insurance for existing structures in flood-prone areas,
provided that the community with jurisdiction regulates the
location and construction of new buildings to minimize future
flood losses.  New structures that comply with the restrictions
are eligible for insurance at full actuarial rates»

     The program is second only to the Social Security Act in the
magnitude of potential government liability.  In 1979, the
program took in $140 million in premiums and paid $480 million
in payment claims.  Recently, the program was authorized to apply
                              8-30

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Chapter 8
claims payments to relocation expenses for structures exposed to
repeated flood or erosion damage.

     Where rainfall and flooding increase, the 100-year
floodplain would expand, and rate maps would need revision.
Premium payments and claims would rise.
RESEARCH NEEDS

1.   Refine global climate change models so that water resource
     engineers and managers in regional planning can use their
     predictions more confidently.

2.   Monitor atmospheric, oceanic, and hydrological conditions to
     detect evidence of water resource impacts of climate change.

3.   Conduct research to identify implementable opportunities for
     adjusting and adapting to climate change.  Types of research
     include the following:

     o    Identify and quantify the relative vulnerabilities of
          water uses to climate change.

     o    Focus research and monitoring on vulnerable water
          resource areas, such as the western edge of the Great
          Plains, where moisture is the limiting factor for
          agriculture, and river basins where demand is greater
          than developed safe yield supply under current
          conditions.

     o    Quantify Federal and Native American water rights in
          the West.

     o    Along with estimating how much water may be required
          for the various uses, develop information on the cost
          and worth or value of water in the various uses.

     o    Examine how present institutions can better allocate
          water among users and provide incentives to conserve
          water and  assess the extent to which laws and
          regulations exacerbate the effects of climate change
          (examples include thermal controls for rivers and
          Federal pricing and reallocation policies for
          irrigation water).
                              8-31

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                                        Water Resources
Identify, project, and quantify economic, demographic,
and institutional adjustments that may accompany
climate induced impacts on water resources in the
absence of concerted public action to provide data upon
which to base policy decisions regarding action
alternatives.
                                                          I
                     8-32
                                                          I

-------
Chapter 8
BIBLIOGRAPHY

Beran, M.  1986.  The water resource impact of future climate
change and variability.  In: Titus, J., ed. Effects of Changes  in
Stratospheric Ozone and Global Climate. Vol. 1: Overview.
Washington, DC: U.S. Environmental Protection Agency, pp. 299-
330.

Butcher, W.R., and N.K. Whittlesey.  1986.  Competition between
irrigation and hydropower in the Pacific Northwest.  In:
Frederick, K.D., ed. Scarce Water and Institutional Change.
Washington, DC: Resources for the Future.

Cohen, S.J.  1986.  Impacts of C02-induced climatic change on
water Resources in the Great Lakes Basin.  Climatic Change
8:135-53.

U.S. Congress, Congressional Budget Office.  May 1987.  Financing
Municipal Water Supply Systems.

Dracup, J.A.  1977.  Impact on the Colorado River Basin and
Southwest water supply.  In:  The National Research Council, ed.
Climate, Climatic Change, and Water Supply.  Washington, DC:
National Academy of Sciences, pp. 121-132.

Emel, J.L.  1987.  Groundwater rights:  definition and transfer.
Natural Resources Journal 27:653-674.

Farber, K.D., and G.L. Rutledge. 1987. Pollution Abatement and
Control Expenditure, 1982-85.  Survey of Current Business. May
1987 pp.  21-26.

Frederick, K.D., and J.C. Hansen. 1982. Water for Western
Agriculture.  Washington, DC:  Resources for the Future.

Frederick, K.D.  1986.  Scarce Water and Institutional Change.
Washington, DC:  Resources for the Future.

Frederick, K.D., and A.V. Kneese.  1988.  Reallocation by markets
and prices.  In:  American Association for the Advancement of
Science Report:  Climatic Variability, Climate Change, and U.S.
Water Resources.  Washington, D.C.

Gibbons, D.C.  1986.  The Economic Value of Water.  Washington,
DC:  Resources for the Future.
                               8-33

-------
                                                  Water Resources
Gleick, P.H.  1987.  Regional Hydrologic Consequences of
Increases in Atmospheric C02 And Other Trace Gases.   Climatic
Change 10: 137-161.

Gleick, P.H.  1988.  The sensitivities and vulnerabilities of
water supply systems to climatic changes.  In:  American
Association for the Advancement of Science Report:  Climatic
Variability, Climate Change, and U.S. Water Resources.
Washington, D.C.

Hanchey, J.R., K.E. Schilling, and E.Z. Stakhiv.  1987.  Water
resources planning under climate uncertainty.  In:  Preparing for
Climate Change.  Proceedings of the First North American
Conference on Preparing for Climate Change.  Government
Institutes, Inc.  pp. 394-405.

Hansen, J., A. Lacis, D. Rind, G. Russell, I. Fung, P. Ashcraft,
S. Lebedeff, R. Ruedy, and P. Stone.  1986.  The greenhouse
effect:  projections of global climate change.  In:  Titus, J.,
ed.  Effects of Changes in Stratospheric Ozone and Global
Climate. Vol. 1: Overview.  Washington, DC:  U.S. Environmental
Protection Agency, pp. 199-218.

Harkness, W.E., H.F. Lins, and W.M. Alley.  1985.  Drought in the
Delaware River Basin.  In:  National Water Summary.  1985:
Hydrologic Events and Surface-Water Resources.  U.S. Geological
Survey,  pp. 29-40.

Hobbs, B.F., and P.M. Meier.  1979.  An analysis of water
resources constraints on power plant siting in the Mid-Atlantic
States.  Water Resources Bulletin 15(6):1666-1676.

Hrezo, M.S., P.G. Bridgeman, and W.R. Walker.  1986.  Integrating
drought planning into water resources management.  Natural
Resources Journal 26:141-167.

Kaplan, E., M. Rubino, and D. Neuhaus.  1981.  Water Resource
Development and Energy Growth in the Northeast.  Brookhaven
National Laboratory, Report BNL 51522; November.

Klemes, V., and J. Nemec.  1985.  Assessing the impact, of climate
change on the development of surface water resources. In:  Klemes
V., ed. Sensitivity of Water Resource Systems to Climate
Variations.  Geneva:  World Meteorological Office.
                              8-34

-------
Chapter 8
Kneese, A.V. and G. Bonem. 1986. Hypothetical shocks to water
allocation institutions in the Colorado Basin. In:  Weatherford,
G., and F.L. Brown, eds. New Courses for the Colorado River:
Major Issues for the Next Century. Albuquerque:  University of
New Mexico Press, pp. 87-108.

Linsley, R.K., and J.B. Franzini.  1979.  Water Resources
Engineering.  New York:  McGraw-Hill, Inc.

Manabe, S., and R.T. Wetherald.  1986.  Reduction in summer soil
wetness induced by an increase in atmospheric carbon dioxide.
In:  Titus, J., ed.  Effects of Changes in Stratospheric Ozone
and Global Climate. Vol. 1: Overview.  Washington, DC: U.S.
Environmental Protection Agency, pp. 249-256.

Matalas, N.C., and M.B. Fiering.  1977.  Water-resource systems
planning.  In:  The National Research Council, ed. Climate,
Climatic Change, and Water Supply.  Washington, DC:  National
Academy of Sciences,  pp. 99-110.

National Council on Public Works Improvement.  1988.  Fragile
Foundations:  A Report on America's Public Works.  Final Report
to the President and to the Congress.  Washington, DC:  U.S.
Government Printing Office.  February.

National Research Council.  1977.  Climate, Climatic Change, and
Water Supply.  Washington, DC:  National Academy Press.

National Research Council.  1988.  Estimating Probabilities of
Extreme Floods.  National Research Council.  Committee on
Techniques for Estimating Probabilities of Extreme Floods, Water
Science and Technology Board; and Commission on Physical
Sciences, Mathematics, and Resources.  Washington, DC:  National
Academy Press.

Nemec, J. , and J.C. Schaake.   1982.  Sensitivity of water
resource systems to climate variation.  Hydrological Sciences
Journal 27:327-43.

Revelle, R.R., and P.E. Waggoner.  1983.  Effects of the carbon
dioxide induced climatic change on water supplies in the western
United States.  In:  Changing Climate:  Report of the Carbon
Dioxide Assessment Committee.  Washington, DC:  National Academy
Press.
                               8-35

-------
                                                  Water Resources
Rind, D., and S. Lebedeff.  1984.  Potential Climatic Impacts of
Increasing Atmosphere C02 With Emphasis  on Water Availability and
Hydrology in the United States.  U.S. Environmental Protection
Agency Report.  Washington, DC:  U.S. Environmental Protection
Agency.

Rosenberg, N.J.  1988.  Global climate change holds problems and
uncertainties for agriculture.  In:  Tutwiler, M.A., ed. U.S.
Agriculture in a Global Setting.  Washington, DC:  Resources for
the Future.

Saliba,  B.C., D.B. Bush, W.E. Martinard, T.C. Brown.  1987.  Do
water market prices appropriately measure water values?  Natural
Resources Journal 27:617-652.

Schwarz, H.E.  1977.  Climatic change and water supply:  how
sensitive is the Northeast?  In:  The National Research Council,
ed. Climate, Climatic Change, and Water Supply.  Washington, DC:
National Academy of Sciences, pp. 111-120.

Sheer, D.P.  1985.  Managing water supplies to increase water
availability. In: National Water Summary.  Hydrologic Events and
Surface-Water Resources.  U.S. Geological Survey, pp. 101-112.

Stockton, C.W., and W.R. Boggess.  1979.  Geohydrological
Implications of Climate Change on Water Resource Development.
Fort Belvoir, VA:  U.S. Army Coastal Engineering Research Center.

Strock,  J.M.  1987.  Adjusting water allocation law to meet water
quality and availability concerns in a warming world.
In:  Preparing for Climate Change.  Proceedings of the First
North American Conference on Preparing for Climate Change.
Rockville, MD:  Government Institutes, Inc., pp.382-387.

Tarlock, A.D.  1987.  Damning the dams and ditches:  a review of
D. Worster, rivers of empire:  water aridity and the American
West.  Natural Resources Journal 27: 477-490.

Trelease, F.J.  1977.  Climatic change and water law.  In: The
National Research Council, ed. Climate,  Climatic Change, and
Water Supply.  Washington, DC:   National Academy of Sciences,
pp. 70-84.

Tripp, J.T.B. and A.B. Jaffe.  1979.  Preventing ground water
pollution:  toward a coordinated strategy to protect critical
recharge zones.  Harvard Environmental Law Review 3.
                              8-36

-------
Chapter 8
Solley, W.B., C.F. Merck, and R.R. Pierce.  Estimated use of
water in the United States in 1985.  U.S. Geological Survey.
Circular 1004 Washington, D.C. U.S. Government Printing Office.

U.S. Army Corps of Engineers.  1977.  Northeastern United States
Water Supply Study, Summary Report.  U.S. Army Corps of
Engineers, North Atlantic Division; July.

U.S. Army Corps of Engineers.  1988.  Lessons Learned from the
1986 Drought.  U.S. Army Corps of Engineers, Water Resources
Support Center, The Hydrologic Engineering Center; June.

U.S. Department of Agriculture.  1987.  Economic Research
Service.  Agricultural Irrigation and Water Supply.  Washington,
DC: U.S. Government Printing Office.  Agriculture Information
Bulletin 532.

U.S. Department of the Interior, Bureau of Reclamation.  1987
Assessment '87 ...A New Direction for the Bureau of Reclamation.
Washington, D.C.

U.S. Department of the Interior, Bureau of Reclamation. 1987
Implementation Plan ...A New Direction for the Bureau of
Reclamation.   Washington, D.C.

U.S. EPA. 1987a.  U.S. Environmental Protection Agency.  1986
Needs Survey Report to Congress: Assessment of Needed Publically
Owned Wastewater Treatment Facilities in the United States.  EPA
430/9-87-001.

U.S. EPA. 1986b.  U.S. Environmental Protection Agency.  National
Water Quality Inventory: 1986 Report to Congress.  EPA-440/4-87-
008.

U.S. Geological Survey.  1984.  National Water Summary.  Water-
supply Paper 2275.  Washington, DC:  U.S. Government Printing
Office.

U.S. Geological Survey.  1985.  National Water Summary.  Water-
supply Paper 2300.  Washington, DC:  U.S. Government Printing
Office.

U.S. Water Resources Council.  1978.  The Nation's Water
Resources 1975-2000: Second National Water Assessment.   Vol.  1:
Summary.  Washington,  D.C.  U.S. Government Printing Office.
                               8-37

-------
                                                  Water Resources
Viessman Jr., W.,  and C. DeMoncada.  1980.  State and National
Water Use Trends to the Year 2000.  Congressional Research
Service, The Library of Congress.

Wahl, R.W.,  and F.H. Osterhoudt.  1985.   Voluntary transfers of
water in the West.  In:  U.S. Geological Survey.  National Water
Summary.  Hydrologic Events and Surface-water Resources, pp. 113-
124.
                              8-38

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                            CHAPTER 9

                          SEA LEVEL RISE

FINDINGS

Global warming could cause a sea level rise of 0.5 to 2m by 2100.
Such a rise would inundate wetlands and lowlands, erode beaches,
exacerbate coastal flooding, and increase the salinity of
estuaries and aquifers.

o    A one-meter rise by the year 2100 could drown approximately
     25 to 80 percent of the U.S. coastal wetlands.  Their
     ability to survive would depend largely on whether they
     could migrate inland or whether levees and bulkheads block
     their path of migration.

o    A one-meter rise could inundate 5,000-10,000 square miles of
     dryland if shores are not protected, and 4,000-9,000 square
     miles of dryland if only developed areas are protected.

o    Most coastal barrier island communities would probably
     respond to sea level rise by raising land with sand pumped
     from offshore.  Wide and heavily urbanized islands may use
     levees, while communities on lightly developed islands may
     adjust to a gradual landward migration of the islands.

o    Protecting developed areas against such inundation and
     erosion by building of bulkheads and levees, pumping sand,
     and raising barrier islands would cost $73-111 billion
     (cumulative capital costs in 1985 dollars)  for a one-meter
     rise by the year 2100.

o    Developed barrier islands would likely be protected from sea
     level rise because of their high property values.  However
     it would cost $50-75 billion (cumulative capital costs in
     1985 dollars) to elevate beaches, houses, land,  and roadways
     by the year 2100.

Policy Implications

o    Many of the necessary responses to sea level rise need not
     be implemented until the rise is imminent,  such as
     rebuilding ports, constructing levees, and pumping sand onto
     beaches.  On the other hand, the cost of incorporating sea
     level rise into a wide variety of engineering and land use
     decisions would be negligible compared to the costs of not
     responding until sea level rises.

o    Wetland ecosystems are likely to survive sea level rise only
     if appropriate measures are implemented soon.  At the states
     and local levels, these measures include land use planning,

                               9-1

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                                                   Sea Level Rise

     regulation, and redefinitions of property rights.  The State
     of Maine has already issued regulations to enable wetlands
     to migrate landward by requiring that structures be removed
     as sea level rises.

o    The coastal wetlands protected under Section 404 of the
     Clean Water Act will gradually be inundated.  The Act does
     not authorize measures to ensure survival of wetland
     ecosystems as sea level rises.  Additional statutory
     authorities might be needed to protect migrating wetlands.

o    The National Flood Insurance Program may wish to consider
     the implications of examining the sea level rise on
     potential liabilities.  A recent HUD authorization act
     requires this program to purchase property threatened with
     erosion.  The act may imply a commitment by the federal
     government to compensate property owners for losses due to
     sea level rise.

CAUSES, EFFECTS, AND RESPONSES

Introduction

     The global warming from the greenhouse effect could raise
sea level approximately one meter by expanding ocean water,
melting mountain glaciers, and causing ice sheets in Greenland to
melt or slide into the oceans.  Such a rise would inundate
coastal wetlands and lowlands, erode beaches, increase the risk
of flooding, and increase the salinity of estuaries, aquifers,
and wetlands.

     In the last five years, many coastal communities throughout
the world have started to prepare for the possibility of such a
rise.  In the United States, Maine has enacted a policy declaring
that shorefront building will have to be moved to enable beaches
and wetlands to migrate inland to higher ground.  Maryland has
shifted its shore-protection strategy from a technology that can
not accommodate sea level rise to one that can.  Seven coastal
states have held large public meetings on how to prepare for a
rising sea.  Australia and the Netherlands are beginning to
undergo a similar process.

Causes

     Ocean levels have always fluctuated with changes in global
temperatures.  During the ice ages when the earth was 5°C  (9°F)
colder than today, much of the ocean's water was frozen in
glaciers and sea level often was more than 100 meters (300 feet),
below the present level (Donn et al., 1962;  Kennett, 1982;
Oldale, 1985).  Conversely, during the last interglacial period

                               9-2

-------
Chapter 9

(100,000 years ago) when the average temperature was about 1°C
(2°F) warmer than today, sea level was approximately 20 feet
higher than current sea level  (Mercer, 1968).

     When considering shorter periods of time, worldwide sea
level rise must be distinguished from relative sea level rise.
Although climate change alters worldwide sea level, the rate of
sea level rise relative to a particular coast has greater
practical importance and is all that monitoring stations can
measure.  Because most coasts are sinking (and a few are rising),
the range of relative sea level rise varies from more than 3 feet
per century in Louisiana and parts of California and Texas to 1
foot per century along most of the Atlantic and Gulf coasts, and
to a slight drop in much of the Pacific Northwest (Figure 9-1).
Areas such as Louisiana provide natural laboratories for
assessing the possible effects of future sea level rise (Lyle et
al., 1987).

     Global sea level trends have generally been estimated by
combining the trends at tidal stations around the world.  Studies
combining these measurements suggest that during the last
century, worldwide sea level has risen 10 to 15 cm (4 to 6
inches) (Barnett, 1984;  Fairbridge and Krebs, 1962).  Much of
this rise has been attributed to the global warming that has
occurred during the last century (Meier, 1984; Gornitz et al.,
1982).  Hughes (1983) and Bentley (1983) estimated that a
complete disintegration of West Antarctica in response to global
warming would require a 200- to 500-year period, and that such a
disintegration would raise sea level 20 feet.  Most recent
assessments, however, have focused on the likely rise by the year
2100.  Figure 9-2 illustrates recent estimates of sea level rise,
which generally fall into the range of 50 to 200 cm.

      Although most studies have focused on the impact of global
warming on global sea level, the greenhouse effect would not
necessarily raise sea level by the same amount everywhere.
Removal of water from the world's ice sheets would move the
earth's center of gravity away from Greenland and Antarctica and
would thus redistribute the oceans'  water toward the new center
of gravity.  Along the U.S. coast,  this effect would generally
increase sea level rise by less than 10%.  Sea level could
actually drop, however, at Cape Horn and along the coast of
Iceland.  Climate change could also effect local influences on
sea level by changing ocean currents, winds, and atmospheric
pressure; no one has estimated these impacts.
      Other processes such as  changes  in ocean basins  have also
played a role, albeit over longer periods of time.

                               9-3

-------
                                                                             I
               TIME, YEARS

               1850  1865  1880  1895   1910  1925  1940  1955  1970  1985
                 f '  'I i  'I  '  ' i  '  I~]''  I '  '  I '  '  I '  """I '  r~~\
                 -7.0
                 -6.6
                 -6.2
                 -5.8
                 l-5.4
                                     SITKA, AK
                               NEW YORK, NY
                       GALVESTON, TX
                           CHARLESTON, SC
Figure 9-1.   Time Series Graph of Sea  Level Trends  for New  York,
               Charleston, Miami,  Galveston, and Sitka

Source:   Lyle et al,  1987.
                                   9-4

-------
   CO
  to
  00
  O)


  o


  UJ
  oc

  UJ
  UJ


  UJ
  UJ
      4.0 r-
       3.0
2.0
       1.0
                                               • Hoffman (1983) High
Glacier Volume Estimate of Polar

Board Augmented With Thermal

Expansion Estimates by NRG

(1983)
• Hoffman (1983) Mid-High


• NRC(1985b) High
                                ,WMD High
                                          Hoffman (1983) Mid-Low
                                                 NRG (1983)


                                            J_  • Hoffman (1983) Low
                                               • NRC(1985b) Low*
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                                      I	I
                           2000
                              2050

                            YEAR
                                2100
Figure 9-2.   Estimates of Future  Sea Level Rise


Source:  Hoffman (1983,  1986); Meier (1985);  Revelle (1983);

          Wigley  (1987,  Thomas


                                    9-5

-------
                                                   Sea Level Rise

Effects

     In this section and in the following sections, the effects
of, and responses to sea level rise are presented separately.
However, the distinction is largely academic and is solely for
presentation purposes.  In many cases, the responses to sea level
rise are sufficiently well-established and the probability of no
response is sufficiently low that it would be misleading to
discuss the potential effects without also discussing responses.
For example, much of Manhattan Island is less than 2 m above high
tide; the effect of sea level rise would almost certainly be the
increased use of coastal engineering structures and not the
inundation of downtown New York.

     A rise in sea level would inundate wetlands and lowlands,
accelerate coastal erosion, exacerbate coastal flooding, threaten
coastal structures, raise water tables, and increase the salinity
of rivers, bays, and aguifers (Earth and Titus, 1984).  Most of
the wetlands and lowlands are found along the Gulf coast and
along the Atlantic coast south of central New Jersey,  although a
large area also exists around San Francisco Bay.  Similarly, the
areas vulnerable to erosion and flooding are also predominately
in the Southeast; potential salinity problems are spread more
evenly along the U.S. Atlantic coast.  We now discuss some of the
impacts that would result if no responses were initiated to
address sea level rise.

Destruction of Coastal Wetlands

     Coastal wetlands are generally found between the highest
tide of the year and mean sea level.  Wetlands have kept pace
with the past rate of sea level rise because they collect
sediment and produce peat upon which they can build; meanwhile
they, expanded inland as lowlands were undated (Fig 9-3) .
Wetlands accrete vertically and expand inland.  Thus,  as Figure
9-2 illustrates, the present area of wetlands is generally far
greater than the area that would be available for new wetlands as
sea level rises (Titus et al., 1984b;  Titus, 1986).  The
potential loss would be the greatest in Louisiana (see Chapter 6,
Southeast.)

     In many areas, people have built bulkheads just above the
marsh.  If sea level rises, the wetlands would be squeezed
between the sea and the bulkheads (see Figure 9-3).  Previous
studies have estimated that if the development in coastal areas
is removed to allow new wetlands to form inland, a 1.5- to 2-m
rise would destroy 30 to 70% of the U.S. coastal wetlands.  If
levees and bulkheads are erected to protect today's dry land, the
loss could be 50 to 80% (Park, 1986; Titus, 1988; Armentano et
al., 1988).  Such a loss would reduce the available habitat for

                               9-6

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                                                   Sea Level Rise

birds and juvenile fish and would reduce the production  of
organic materials on which estuarine fish rely.

     The dry land within 2 m of high tide includes forests,
farms, low parts of some port cities, cities that sank after they
were built and are now protected with levees, and the bay sides
of barrier islands.  The low forests and farms are generally in
the mid-Atlantic and Southeast regions; these would provide
potential areas for new wetland formation.  Major port cities
with low areas include Boston, New York, Charleston, and Miami.
New Orleans is generally 8 feet below sea level, and parts of
Galveston, Texas City, and areas around the San Francisco Bay are
also well below sea level.  Because they are already protected by
levees, these cities are more concerned with flooding than with
inundation.

Inundation and Erosion of Beaches and Barrier Islands

     Some of the most important vulnerable areas are the
recreational barrier islands and spits  (peninsulas) of the
Atlantic and Gulf coasts.  Coastal barriers are generally long
narrow islands and spits with the ocean on one side and  a bay on
the other.  Typically, the oceanfront block of an island ranges
from 5 to 10 feet above high tide, and the bay side is 2 to 3
feet above high water.  Thus, even a 1-m sea level rise  would
threaten much of this valuable land with inundation.

     Erosion threatens the high part of these islands and is
generally viewed as a more immediate problem than the inundation
of the bay sides.  As Figure 9-4 shows, a rise in sea level can
cause an ocean beach to retreat considerably more than it would
from the effects of inundation alone.  The visible part  of the
beach is much steeper than the underwater portion, which
comprises most of the active "surf zone."  While inundation alone
is determined by the slope of the land just above the water,
Bruun (1962) and others have shown that the total shoreline
retreat from a sea level rise depends on the average slope of the
entire beach profile.

     Previous studies suggest that a 1-foot rise in sea  level
would generally cause beaches to erode 50-100 feet from  the
Northeast to Maryland (e.g., Kyper and Sorensen, 1985; Everts,
1985); 200 feet along the Carolinas  (Kana et al., 1984);
100-1,000 feet along the Florida coast  (Bruun, 1962); 200-400
feet along the California coast (Wilcoxen, 1986); and perhaps
several miles in Louisiana.  Because most U.S. recreational
beaches are less than 100 feet wide at high tide, even a 1-foot
rise in sea level would require a response.   In many area^
undeveloped barrier islands could Jceep up with rfci'iU '   ,
by "overwashxng" landward.   Ia LouisianaI,™>Ver, ^S    ^

                              9-8

-------
                 B
Figure 9-4.
The Bruun Rule. A, initial condition; B, Immediate
inundation when sea level rises; C, subsequent
erosion due to sea level rise.  A rise in sea level
immediately results in shoreline retreat due to
inundation, shown in the first two examples.
However, aim rise in sea level implies that the
offshore bottom must also rise 1 m.  The sand
required to raise the bottom  (A1) can be supplied by
beach nourishment.  Otherwise, waves will erode the
necessary sand (A) from upper part of the beach as
shown in C.
Source:  Titus, 1986.
                               9-9

-------
                                                   Sea Level Rise

islands are breaking up and exposing the wetlands behind them to
gulf waves; consequently, the Louisiana barrier islands have
rapidly eroded.

Flooding

     Flooding would increase along the coast if sea level rises
for three reasons:  (1) A higher sea level provides a higher base
for storm surges to build upon.  A 1-m sea level rise would
enable a 15-year storm to flood many areas that today are flooded
only by a 100-year storm (e.g., Kana et al., 1984; Leather-man,
1984).  (2) Beach erosion also would leave oceanfront properties
more vulnerable to storm waves.  (3) Higher water levels would
reduce coastal drainage and thus would increase flooding
attributable to rainstorms.  In artificially drained areas such
as New Orleans, the increased need for pumping could exceed
current capacities.  Finally,  (4) a rise in sea level would raise
water tables and would flood basements and in cases where the
groundwater is just below the surface perhaps leach it above the
surface.

Saltwater Intrusion

     Finally, a rise in sea level would enable saltwater to
penetrate farther inland and upstream into rivers, bays,
wetlands,  and aquifers.  Salinity increases would be harmful to
some aquatic plants and animals, and would threaten human uses of
water.  For example, increased salinity already has been cited as
a factor contributing to reduced oyster harvests in the Delaware
and Chesapeake Bays, and to conversion of cypress swamps in
Louisiana to open lakes.  Moreover, New York, Philadelphia, and
much of California's Central Valley obtain their water from areas
located just upstream from areas where the water is salty during
droughts.   Farmers in central New Jersey and the city of Camden
rely on the Potomac-Raritan-Magothy aquifer, which could become
salty if sea level rises (Hull and Titus, 1986).  The South
Florida Water Management District already spends millions of
dollars every year to prevent Miami's Biscayne Aquifer from
becoming contaminated with seawater.

Responses

     The possible responses to inundation, erosion, and flooding
fall broadly into three categories:  erecting walls to hold back
the sea, allowing the sea to advance and adapting to the advance,
and raising the land.   Both the slow rise in sea level over the
last thousand years and the areas where land has been sinking
more rapidly offer numerous historical examples of all three
responses.
                              9-10

-------
Chapter 9

     For over five centuries, the Dutch and others have used
dikes and windmills to prevent inundation from the North Sea.  By
contrast, many cities have been rebuilt landward as structures
have eroded; the town of Dunwich, England, has rebuilt its church
seven times in the last seven centuries.  More recently, rapidly
subsiding communities (e.g., Galveston, Texas) have used fill to
raise land elevations; the U.S. Army Corps of Engineers and
coastal States regularly pump sand from offshore locations to
counteract beach erosion.  Venice, a hybrid of all three
responses, has allowed the sea to advance into the canals, has
raised some lowlands, and has erected storm protection barriers.

     Most assessments in the United States have concluded that
low-lying coastal cities would be protected with bulkheads,
levees, and pumping systems, and that sparsely developed areas
adapt to a naturally retreating shoreline (e.g., Dean etal.,
1987; Gibbs, 1984; Schelling, 1983).  This conclusion has
generally been based on estimates that the cost of structural
protection would be far less than the value of the urban areas
being protected but would be greater than the value of
undeveloped land.

     Studies on the possible responses of barrier islands and
moderately developed mainland communities show less agreement but
generally suggest that environmental factors would be as
important as economics.   Some have suggested that barrier islands
should use seawalls and other "hard" engineering approaches
(e.g.,  Kyper and Sorensen,  1985; Sorensen, 1984).  Others have
pointed to the aesthetic problems associated with losing beaches
and have advocated a gradual retreat from the shore (Howard et
al., 1985).  Noting that new houses on barrier islands are
generally elevated on pilings,  Titus (1986)  suggested that
communities could hold back the sea but keep a natural beach by
extending the current practice of pumping sand onto beaches to
raising entire islands in place.

     Responses to erosion are more- likely to have adverse
environmental impacts along sheltered water than on the open
coast (Titus, 1986) .  Because the beach generally is a barrier
island's most important asset,  economics would tend to encourage
these communities to preserve their natural shorelines; actions
that would prevent the island from breaking up also would protect
the adjacent wetlands.  However, along most mainland shorelines,
economic self-interest would encourage property owners to erect
bulkheads; these would prevent new wetland formation from
offsetting the loss of wetlands that were inundated.

     Most of the measures for counteracting saltwater intrusion
 ttributable to sea level rise have also been employed to address
        problems.  For example, the Delaware River Basin

                               9-11

-------
                                                   Sea Level Rise

Commission protects Philadelphia's freshwater intake on the river
and New Jersey aquifers recharged by the river by storing water
in reservoirs during the wet season and releasing it during
droughts, thereby forcing the saltwater back toward the sea.
Other communities have protected coastal aquifers by erecting
underground barriers and by maintaining freshwater pressure
through the use of impoundments and injection wells.
HOLDING BACK THE SEA: A NATIONAL ASSESSMENT

     The studies referenced in the previous section have
illustrated a wide variety of possible effects from and responses
to a rise in sea level from the greenhouse effect.  Although they
have identified the implications of the risk of sea level rise
for specific locations and decisions,  these studies have not
estimated the nationwide magnitude of the impacts.   This report
seeks to fill that void.

    It was not possible to estimate the nationwide value of every
impact of sea level rise.  The studies thus far conducted suggest
that the majority of the environmental and economic costs would
be associated with shoreline retreat and measures to hold back
the sea, which can be more easily assessed on a nationwide basis,
thus other impacts.  Because the eventual impact will depend on
what people actually do, a number of important questions can be
addressed within this context:

     o     Would a gradual abandonment of moderately developed
           mainland areas significantly increase the amount of
           wetlands that survived a rise in sea level?

     o     Would the concave profiles of coastal areas ensure
           that more wetlands would be lost than gained,
           regardless of land-use decisions?

     o     Should barrier islands be raised in place by pumping
           sand and elevating structures and utilities?

     o     Would a landward migration of developed barrier
           islands or to encircling them with dikes and levees be
           feasible alternatives?

     o     How much property would be lost if barrier islands
           were abandoned?
                                                                    I
                              9-12

-------
Chapter 9

STRUCTURE OF STUDIES FOR THIS REPORT

     Figure 9-5 illustrates the relationships between the various
studies.  As the top portion shows, investigators began with a
case study of Long Beach Island, New Jersey.  A case study was
due to develop and evaluate methods for the national analysis.
The Park and Leatherman studies performed the same calcualtion
for the case study and the other sites included in the national
assessment, with Park estimating the loss of wetlands and
dryland, and Leatherman estimating the cost of dredging
sufficient sand to raise recreational beaches and coastal barrier
islands. However, Weggel and Yohe conducted detailed assessments
for the case study that were not repeated for the other sites;
the results were used in the Leatherman and Titus studies.

     A central theme underlying these questions is that the
implications of sea level rise for a community depend greatly on
whether people adjust to the natural impact of shoreline retreat
or undertake efforts to hold back the sea.  Because no one knows
the extent to which each of these approaches would be applied,
this study was designed to estimate the impacts of sea level rise
for (1) holding back the sea, and (2)  natural shoreline retreat.

     The tasks were split into five discreet projects:

     I.    Park et al. estimated the loss of coastal wetlands and
           dryland.
     2.    Leatherman estimated the cost of pumping sand onto
           open coastal beaches and barrier islands.
     3.    Weggel et al. estimated the cost of protecting
           sheltered shores with leaves and bulkheads.
     4.    Yohe began a national economic assessment by
           estimating the value of threatened property.
     5.    Titus and Greene synthesized the results of other
           studies to estimate ranges of the nationwide impacts.

     Figure 9-5 illustrates the relationships between the various
reports.  As the top portion shows,  the assessment began with a
case study of Long Beach Island, New Jersey, which was necessary
for evaluating methods and providing data for purposes of
extrapolation.  The Park and Leatherman studies performed the
same calculations for the case study site that they would
subsequently perform for the other sites in the nationwide
analysis.   However, Weggel and Yohe conducted more detailed
assessments of the case study whose results were used in the
Leatherman and Titus studies.

     Because it would not be feasible for Leatherman to examine
more than one option for the cost of protecting the open coast,
Weggel estimated the cost of protecting Long Beach island by

                               9-13

-------
       Park
 Weggel
 Leatherman
          CASE STUDY

          NATIONAL ANALYSIS
     Yohe
                                                                                   I
             Park
    Weggel
 Leatherman
     Loss of
     Wet and
     Dry Land
 Cost of
Protecting
Sheltered
  Shore
                                                                     Titus
                                                                      &
                                                                    Greene
 Sand Cost
for Protecting
 Open Coast
1. Non-Sand Cost
  of Raising
  Barrier Islands

2. Ranges for
  Wetland/
  Dryland Loss,
  Sand Costs,
  Protecting
  Sheltered
  Shores
Figure 9-5.   Overview  of Sea  Level Rise Studies-Authors
                                    9-14

-------
Chapter 9

three approaches:   (1) raising the island in place;  (2) gradually
rebuilding the island landward; and  (3) encircling the island
with dikes and levees; Yohe estimated the value of threatened
structures.  Titus analyzed Weggel's and Yohe's results and
concluded that raising barrier islands would be the most
reasonable option for the Leatherman study.  They also noted that
the cost of this option would be considerably less than the
resources that would be lost if the islands are not protected as
shown in Figure 9-6.

     Once the case study was complete, Park, Leatherman, and
Weggel proceeded independently with their studies (although Park
provided Weggel with elevation data).  When those studies were
complete, Titus synthesized their results, developing a
nationwide estimate of the cost of holding back the sea and
interpolating Weggel's 200-cm results for the 50- and 100-cm
scenarios.

     In presenting results from the Park and Weggel studies, the
sites were grouped into seven coastal regions, four of which are
in the Southeast:  New England, mid-Atlantic, south Atlantic,
south Florida/gulf coast peninsula, Louisiana, other gulf (Texas,
Mississippi, Alabama, Florida Panhandle),  and the Pacific coast.
Figure 9-7 illustrates these regions.
SCENARIOS OF SEA LEVEL RISE

     Although the researchers considered a variety of scenarios
of future sea level rise, this report focuses on the impacts of
three scenarios: rises of 50, 100, and 200 cm by the year 2100.
Following this convention of a recent National Research Council
report (Dean et al., 1987), the rise was interpolated throughout
the 21st century using a parabola, as shown in Figure 9-8.  For
each site, local subsidence was added to determine relative sea
level rise.  Along the coast of Florida (which is typical of most
of the U.S. coast), sea level would rise 1 foot by 2025, 2040,
and 2060 for the three scenarios and 2 feet by 2045, 2065, and
2100.
RESULTS OF SEA LEVEL STUDIES IN THIS REPORT

Loss of Coastal Wetlands and Dryland

     Park sought to test a number of hypotheses presented in
previous publications:
                               9-15

-------
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                                                                      I
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Figure 9-8.  Sea Level  Scenarios (Miami Beach)
                               9-18

-------
Chapter 9

     o     A rise in sea level greater than the rate of vertical
           wetland accretion would result in a net loss of
           coastal wetlands.

     o     The loss of wetlands would be greatest if all
           developed areas are protected, less if shorelines
           retreat naturally, and least if barrier islands are
           protected while mainland shores retreat naturally.

     o     The loss of coastal wetlands would be greatest in the
           Southeast, particularly Louisiana.

Study Design

     Park's study was based on a sample of 46 coastal sites that
were selected at regular intervals.  This guaranteed that
particular regions would be represented in proportion to their
total area in the coastal zone.  The sites chosen accounted for
10% of the U.S. coastal zone.

     To estimate the potential loss of wet and dry land, Park
first had to characterize their elevations.   For wetlands, he
used satellite imagery to determine plant species for 60- by
80-m parcels.  Using estimates from the literature on the
frequency of flooding that can be tolerated by various wetland
plants, Park determined the percentage of time particular parcels
currently under water.  From this, Park inferred wet land
elevation based on the known tidal range.  For dry land, Park
used spot elevation measurements to interpolate between contours
on U.S. Geological Survey topographic maps.

     Park estimated the loss of wetlands and dryland for no
protection, protection of developed areas, and protection of all
shores.  For the no-protection scenario, estimating the loss of
dryland is straightforward.  However,  for calculating wetland
loss, Park used published vertical accretion rates (see Armentano
et al., 1988).  For accelerated sea level rise, he allowed for
some acceleration of vertical accretion in areas with ample
supplies of sediment, such as tidal deltas.

     For sites in the Southeast, Park also allowed for the
gradual replacement of salt marshes by mangrove swamps.  The
upper limit for mangroves is around Fort Lauderdale.   Park used
the GISS transient scenario to determine the year particular
sites would be as warm as Fort Lauderdale is today and assumed
that mangroves would begin to replace marsh after that year.
                               9-19

-------
                                                   Sea Level Rise

Limitations

     The greatest uncertainty in Park's analysis is a poor
understanding of the potential rates of vertical accretion.
Although this could substantially affect the results for low
sea level rise scenarios, the practical significance is small for
a rise of 1 m because it is generally recognized that wetlands
could not keep pace with the rise of 1 to 2 cm/year that such a
scenario implies for the second half of the 21st century.

     Errors can be made when determining vegetation type based on
the use of infrared "signatures" that satellites receive.  Park
noted, for example, that in California the redwoods have a
signature similar to marsh grass.  For only a few sites Park was
able to corroborate his estimates of vegetation type.

    Park's study did not consider the potential implications of
alternative methods of managing riverflow.  This limitation is
particularly serious regarding application to Louisiana, where
widely varying measures have been proposed to increase the amount
of water and sediment delivered to the wetlands.  Finally, the
study makes no attempt to predict which undeveloped areas might
be developed in the next century.

     At the coarse (500-m) scale Park used, the assumption of
only protecting developed areas amounts to not protecting a
number of mainland areas where the shoreline is developed but
areas behind the shoreline are not.  Therefore, Park's estimates
for protecting developed areas should be interpreted as applying
to the case where only densely developed areas are protected.

Results

     Park's results supported the hypotheses suggested by
previous studies.  Figure 9-9 shows nationwide wetland loss for
various (0- to 3-m) sea level rises for the three policy options
investigated.  For a 1-m rise, 66% of all coastal wetlands would
be lost if all shorelines were protected, 49% would be lost if
only developed areas were protected, and 46% would be lost if
shorelines retreated naturally.

      As expected, the greatest losses of wetlands would be in
the Southeast, which currently contains 85% of U.S. coastal
wetlands (Figure 9-9).  For a 1-m sea level rise, 6,000-8,600 mi
(depending on which policy is implemented) of U.S. wetlands would
be lost; 90-95% of these would be in the Southeast, and 40-50%
would be in Louisiana alone.  By contrast, neither the Northeast
nor the West would lose more than 10% of its wetlands if only
currently developed areas are protected.
                              9-20

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                COMPOSITE FOR UNITED STATES


                  A. 3 m ALL DRY LAND PROTECTED
                 0.0  0.1   0.3   0.6  1.0  1.5  2.2  3.0
                                                   SWAMP

                                                  ES-SSSad

                                                 FRESH MARSH
                                                  MANGROVE
                                                  BEACH/FLAT
                                                  L
                                       J
                                                  SALT MARSH
                            SEA LEVEL
                B. 3 m DEVELOPED AREAS PROTECTED
                 0.0  0.1   0.3  0.6  1.0  1.5  2.2  3.0
                                                   SWAMP
                                                 FRESH MARSH
                                                  MANGROVE
                                                  BEACH/FLAT
                                                  L
                                       J
                                                  SALT MARSH
                            SEA LEVEL
                        C.  3 m UNPROTECTED
            UJ
            O
            ff
            UJ
            a.
100


 80



 60


 40


 20


 0


0.0  0.1  0.3  0.6  1.0  1.5

           SEA LEVEL
                                         2.2  3.0
                                                   SWAMP

                                                  Kfttm&\
                                                 FRESH MARSH
                                 MANGROVE
                                                  BEACH/FLAT
                                                        J
                                                  SALT MARSH
Figure 9-9.   Nationwide Wetland Loss for  Three  Shoreline-

               Protection Options


Source:   Park, Volume  	.
                                    9-21

-------
                                                   Sea Level Rise

     Figure 9-10 illustrates Park's estimates of the inundation
of dryland for the seven coastal regions.  If shorelines retreat
naturally, a 1-m rise would inundate 7,700 mi2  of  dryland,  an
area the size of Massachusetts.  Rises of 50 and 200 cm would
result in losses of 5,000 and 12,000 mi2,  respectively.

Approximately 70% of the dryland losses would occur in the
Southeast, particularly Florida, Louisiana, and North Carolina.
The eastern shores of the Chesapeake and Delaware Bays also would
lose considerable acreage.

Costs of Defending Sheltered Shorelines

Study Design

     This study began by examining Long Beach Island in depth.
This site and five other sites were used to develop engineering
rules of thumb for the cost of protecting coastal lowlands from
inundation.  Examining the costs of raising barrier islands
required an assessment of two alternatives:  (1) building a levee
around the island; and (2) allowing the island to migrate
landward.                                                           *m

     After visiting Long Beach Island and the adjacent mainland,
Weggel designed and estimated costs for an encirclement scheme
consisting of a levee around the island and a drainage system
that included pumping and underground retention of stormwater.
For island migration, he used the Bruun Rule to estimate
oceanside erosion and navigation charts to calculate the amount
of sand necessary to fill the bay an equivalent distance
landward.  For island raising and island migration, Weggel used
the literature to estimate the costs of elevating and moving
houses and of rebuilding roads and utilities.

     Weggel's approach for estimating the nationwide costs was to
examine a number of index sites in depth and thereby develop
generalized cost estimates for protecting different types of
shorelines.  He used the topographic information collected by
Park for a sample of 95 sites to determine the area and shoreline
length that had to be protected.  He then applied the cost
estimation factors to each site and extrapolated the sample to
the entire coast.

     After assessing Long Beach Island, Weggel conducted less
detailed studies of the following areas:  metropolitan New York;
Dividing Creek, New Jersey; Miami and Miami Beach; the. area
around Corpus Christi, Texas; and parts of San Francisco Bay.
                              9-22

-------
  40
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 Florida
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            REGION:
                            BASELINE
  50 CM
      100 CM
             200 CM
  Figure 9-10.  Loss  of  Dry  Land by 2100  (a) without  protection (b)
                   with  protection
  Source:      Derived from Park,  Volume 	;   (see  also Titus  and
                 Green,  Volume  	.)
                                          9-23

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                                                   Sea Level Rise

Limitations

     The most serious limitation of the Weggel study is that
cruder methods are used for the national assessment than for the
index sites.  Even for the index sites, the cost estimates are
based on the literature, not on site-specific designs that take
into consideration wave data for bulkheads and potential savings
from tolerating substandard roads.  Weggel did not estimate the
cost of pumping rainwater out of areas protected by levees.

     Finally, Weggel was able to examine only one scenario:  a
2-m rise by 2100.  This scenario was chosen over the more likely
1-m scenario because an interpolation from 2 m to 1 m would be
more reliable than an extrapolation from 1 m to 2 m. (See the
discussion of Titus and Greene for results of the interpolation.)

Results

     Case Study of Long Beach Island

     Weggel's cumulative cost estimates clearly indicate that
raising Long Beach Island would be much less expensive ($1.7
billion) than allowing it to migrate landward ($7.7 billion).
Although the cost of building a levee around the island ($800
million) would be less, the "present value" would be greater
(Table 9-1).  Weggel concluded that the levee would have to be
built in the 2020s, whereas the island could be raised gradually
between 2020 and 2100.  Thus, the (discounted) present value of
the levee cost would be greater, and raising the necessary
capital for a levee at any one time could be more difficult than
gradually rebuilding the roads and elevating houses as the island
was raised.  Moreover, a levee would eliminate the waterfront
view.

     The Weggel analysis shows that landward migration is more
expensive than island raising, primarily because of the increased
costs of rebuilding infrastructure.   Thus, migration might be
less expensive in the case of a very lightly developed island.
Levees might be more practical for wide barrier islands where
most people do not have a waterfront view.

     Nationwide Costs

     Table 9-2 shows Weggel's estimates for the index sites and
his nationwide estimate.  The index sites represent two distinct
patterns.  Because urban areas such as New York and Miami would
be entirely protected by levees, the cost of moving buildings and
rebuilding roads and utilities would be relatively small.   On the
other hand, Weggel concluded that in more rural areas such as
Dividing Creek, New Jersey, only the pockets of development wou.i

                               9-24

-------
Chapter 9
Table 9-1,
Total Cost of Protecting Long Beach Island From a 2-m
Rise in Sea Level (millions of dollars)
Protective Measure
                               Island     Island
               Encirclement    Raising   Migration
Sand Costs:
Beach
Land creation/maintenance
Moving/elevating houses
Roads/ utilities
Levee and drainage
Total

290
NA
NA
0
542
832

290
270
74
1072
0
1706

0
321
37
7352
0
7710
NA = Not applicable.

Source:  Leatherman, Weggel.
                               9-25

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                                                   Sea Level Rise
Table 9-2.
Cumulative Cost of Protecting Sheltered Waters
(millions of 1986 dollars)
New Raise Old
Bulkhead Bulkhead
Index Sites
New York 57 205
Long Beach 3 4
Dividing Creek 4 6
Miami area 11 111
Corpus Christi 11 29
San Francisco Bay 3 19
Nationwide Estimate
Low
Northeast 6,932
Mid-Atlantic 4,354
Southeast 9,249
West 4,097
Nation 24,633
Move Roads/
Building Utils Total

0.5 9.5
2.7 3.8
4.8 18.2
0.3 8.3
2.8 40.9
2.0 20.0

Hicrh
23,607
14,603
29,883
12,802
80,176

272.3
13.7
33.0
130.7
83.4
44.0







Source:  Weggel et al.
                               9-26

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Chapter 9

be protected.  The roads that connected them would have to be
elevated or replaced with bridges, and the small number of
isolated buildings would have to be moved.

     Weggel estimates that the nationwide cost of protecting
developed shorelines would be $25 billion, assuming bulkheads are
built, and $80 billion assuming levees are built.  Unlike wetland
loss, the cost of protecting developed areas from the sea would
be concentrated more in the Northeast than in the Southeast
because a much greater portion of the southeastern coast is
undeveloped.

Case Study of the Value of Threatened Coastal Property

Study Design

     Yohe's objective was to estimate the loss of property that
would result from not holding back the sea.  Using estimates of
erosion and inundation for Long Beach Island from Leatherman and
Park et al., Yohe determined which land would be lost from
sea level rise for a sample of strips spanning the island from
the ocean to the bay.  He then used the Ocean County, New Jersey,
tax assessor's estimates of the value of the land and structures
that would be lost, assuming that the premium associated with a
view of the bay or ocean would be transferred to another property
owner and not lost to the community.  He estimated the annual
stream of rents that would be lost by assuming that the required
return on real estate is 10% after tax.  Yohe assumed that a
property on the bay side was "lost" whenever it was flooded at
high tide, and that property on the ocean side was "lost" when
the house was within 40 feet of the spring high tide mark.  (See
Titus and Greene, Volume x for discussion.)

Limitations

     Yohe's results for a sea level rise of less than 18 inches
are sensitive to the assumption regarding when a property would
be lost.  On the bay side, people might learn to tolerate tidal
inundation.  Unless a major storm occurred, people could probably
occupy oceanfront houses until they were flooded at high tide.
However, the resulting loss of recreational use of the beach
probably would have a greater impact than abandoning the
structure.  Tax maps do not always provide up-to-date estimates
of property values.  However, the distinction between the tax
assessor's most recent estimate of market value and the current
market value is small compared with the possible changes in
property values that will occur over the next century; hence,
Titus and Greene used tax assessors estimates of market values.
                              9-27

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                                                   Sea Level Rise

Results

     Yohe's results suggest that the cost of gradually raising
Long Beach Island would be far less than the value of the
resources that would be protected.  Figure 9-6 compares Yohe's
estimates of the annual loss in rents resulting from not holding
back the sea with Weggel's estimates of the annual cost of
raising the island for the 2-m scenario.  With the exception of
the 2020s, the annual loss in rents resulting from not holding
back the sea would be far less than the annual costs of pumping
sand and elevating structures.

Nationwide Cost of Pumping Sand Onto Recreational Beaches

     Leatherman's goal was to estimate the cost of defending the
U.S. ocean coast from a rise in sea level.

Study Design

     Owing to time constraints, it was possible to consider only
one technology.  Based on the Long Beach Island results,
Leatherman assumed that the cost of elevating recreational
beaches and coastal barrier islands by pumping in offshore sand
would provide a more representative cost estimate than assuming
that barrier islands would be abandoned, migrate landward, or be
encircled with dikes and levees.

     The first step in Leatherman's analysis was to estimate the
area of (1) the beach system, (2) the low bayside, and (3) the
slightly elevated oceanside of the island.  Given the areas, the
volume of sand was estimated by assuming that the beach system
would be raised by the amount of sea level rise.  The bay and
ocean sides of the island would not be raised until after a rise
in sea level of 1 and 3 feet, respectively.  Cost estimates for
the sand were derived from inventories conducted by the U.S. Army
Corps of Engineers.

     Leatherman applied this method to all recreational beaches
from Delaware Bay to the mouth of the Rio Grande, as well as
California, which accounts for 80% of the nation's beaches.  He
also examined one representative site in each of the remaining
States.

Limitations

     Although the samples of sites in the Northeast and Northwest
are representative, complete coverage would have been more
accurate.  Furthermore, Leatherman used conservative assumptions
in estimating the unit costs of sand.  Generally, a fraction of
the sand placed on a beach washes away because the sand's grain

                               9-28

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Chapter 9

is too small.  Moreover, as dredges have to move further offshore
to find sand, costs will increase.

     For Florida, Leatherman used published estimates of the
percentage of fine-grain sand and assumed that the dredging cost
would rise $1 per cubic yard for every additional mile offshore
the dredge had to move.  For the other States, however, he
assumed that the deposits mined would have no fine-grain sand and
that dredging costs would not increase.  (To test the sensitivity
of this assumption, Titus and Greene developed an increasing-cost
scenario.)  Leatherman assumed no storm worse than the 1-year
storm, which underestimates the sand volumes required.

     A final limitation of the Leatherman study is that it
represents the cost of applying a single technology throughout
the ocean coasts of the United States.  Undoubtedly, some
communities  (particularly Galveston and other wide barrier
islands in Texas) would choose to erect levees and seawalls or to
accept a natural shoreline retreat rather than to pump sand.
This approach may overestimate the costs of pumping sand.

Results

     Table 9-3 illustrates Leatherman's estimates.  A total of
1,900 miles of shoreline would be nourished.  Of 746 mi2  of
coastal barrier islands that would be raised for a 4-foot sea
level rise, 208 mi2 would  be for a 2-foot rise.   As  the table
shows, two-thirds of the nationwide costs would be borne by four
southeastern states:  Texas, Louisiana, Florida, and South
Carolina.

     Figure 9-11 illustrates the cumulative nationwide costs over
time.  For the 50- and 200-cm scenarios, the cumulative cost
would be $2.3-4.4 billion through 2020, $11-20 billion through
2060, and $14-58 billion through 2100.  By contrast, if current
trends continue, the total cost of sea level rise for beach
nourishment would be about $35 million per year.

Synthesis of the Three National Studies

Study Design

     Although Weggel used Park's topographic data, the analysis
in the three nationwide studies proceeded independently.   Titus
and Greene's primary objectives were to combine various results
to estimate the nationwide cost of holding back the sea for
                              9-29

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                                                   Sea  Level  Rise
Table 9-3.
Cost of Placing Sand on U.S. Recreational Beaches and
Coastal Barrier Islands and Spits
State
                               Sea Level Rise by 2100
       Baseline      50 cm       100 cm
       	f$ millions)
                             200 cm
Maine8              22.8
New Hampshire8       8.1
Massachusetts8     168.4
Rhode Island3       16.3
Connecticut8       101.7
New York8  "        143.6
New Jersey8        157.6
Delaware             4.8
Maryland             5.7
Virginia            30.4
North Carolina     137.4
South Carolina     183.5
Georgia             25.9
Florida            120.1
 (Atlantic coast)
Florida            149.4
 (Gulf coast)
Alabama             11.0
Mississippi         13.4
Louisiana        1,955.8
Texas              349.6
California          35.7
Oregon3             21.9
Washington State3   51.6
Hawaii3^             73.5
                     119.4
                      38.9
                     489.5
                      92.0
                     516.4
                     769.6
                     902.1
                      33.6
                      34.5
                     200.8
                     655.7
                   1,157.9
                     153.6
                     786.6

                     904.3

                      59.0
                      71.9
                   2,623.1
                   4,188.3
                     174.1
                      60.5
                     143.0
                     337.6
                216.8
                 73.4
                841.6
                160.6
                944.1
              1,373.6
              1,733.3
                 71.1
                 83.3
                386.5
              1,271.2
              2,147.7
                262.6
              l,791.0b

              l,688.4fc

                105.3
                128.3
              3,492.7
              8,489.7
                324.3
                152.5
                360.1
                646.9
                 412.2
                 142.0
               1,545.8
                 298.2
               1,799.5
               2,581.4
               3,492.5
                 161.8
                 212.8
                 798.0
               3,240.4
               4,347.7
                 640.3
              7,745.5b

              4,091.6b

                 259.6
                 369.5
               5,231.7
              17,608.3
                 625.7
                 336.3
                 794.4
               1,267.5
Nation
     3,788.0
14,512.0
26,745.0
58,002.0
"Indicates States where estimate was based on extrapolating a
 representative site to the entire State.  All other States have
 100% coverage.
bFlorida estimates account for the percentage
 of fine-grain sediment, which generally washes away,  and  for
 cost escalation as least expensive sand deposits are  exhausted.
 All other estimates conservatively ignore this issue.

Source:  Leatherman.   (Baseline derived from Leather-man) .
                               9-30

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-------
                                                   Sea Level Rise

various sea level rise scenarios and to derive ranges for the
specific impacts.

     Titus and Greene undertook the following primary tasks:

1.   Use Park's results to weight Weggel's high and low scenarios
     according to whether levees or bulkheads would be necessary,
     and interpolate Weggel's cost estimate for the 2-m rise to
     rises of 50 and 100 cm.

2.   Use results from Leatherman and Weggel, along with census
     data, to estimate the nationwide cost (other than pumping
     sand) of raising barrier islands.

3.   Develop an increasing-cost scenario for the cost of
     protecting the open ocean coast.

4.   Develop statistical confidence intervals for wet Land loss,
     impacts of the various policy options, and costs of
     protecting developed shores.

     Cost of Protecting Sheltered Shores

     Titus and Greene developed a single estimate for protecting
each site with bulkheads and levees by assuming that the portion
of developed areas protected with levees would be equal to the
portion of the lowlands that Park estimated would be inundated.
They interpolated the resulting 2-m estimate to 50 and 100 cm
estimates, based on Weggel's assumption that the cost of building
bulkheads and levees rises as a function of the structure's
height.

     Cost of Raising Barrier Islands Other Than Dredging

     Weggel's case study of Long Beach Island provided cost
estimates for elevating structures and rebuilding roads,  while
Leatherman estimated the area that would have to be raised.  Many
barrier islands have development densities different from those
of Long Beach Island because they have large tracts of
undeveloped land or larger lot sizes.  Therefore, Titus and
Greene used census data to estimate a confidence interval for the
average building density of barrier islands, and they applied
Weggel's cost factors.

     Sensitivity of Sand Costs to Increasing Scarcity of Sand

     Titus and Greene used Leatherman's escalating cost
assumptions for Florida to estimate sand pumping costs for the
rest of the nation.
                              9-32

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Chapter 9

     Confidence Intervals

     The Park and Weggel studies involved sampling, but the
researchers did not calculate statistical confidence intervals.
Therefore, Titus and Greene developed 95% confidence intervals
for the cost of protecting sheltered coasts, the area of wetland
loss for various scenarios.

Limitations

     Besides all of the limitations that apply to the Park,
Leatherman, and Weggel studies, a number of others apply to Titus
and Greene.

     Cost of Protecting Sheltered Shores

     Titus and Greene assumed that the portion of the coast
requiring levees (instead of bulkheads)  would be equal to the
portion of lowlands that otherwise would be inundated.  This
assumption tends to understate the need for levees.  For example,
a community that is 75% high ground often would still have very
low land along all of its shoreline and hence would require a
levee along 100% of the shore.  But Titus and Greene assume that
only 25% would be protected by levees.

     Cost of Raising Barrier Islands

     The data provided by Weggel focused only on elevating roads,
buildings, and bulkheads.  Thus, Titus and Green do not consider
the cost of replacing sewers, water mains, or buried cables.  On
the other hand, Weggel's cost factors assume that rebuilt roads
would be up to engineering standards; it is possible that
communities would tolerate substandard roads.  In addition, the
census data Titus and Greene used were only available for
incorporated communities, many of which are part barrier island
and part mainland; thus, the data provide only a rough measure of
typical road density.

     Sensitivity of Sand Costs to Increased Scarcity of Sand

     Finally,  Titus and Greene made no attempt to determine how
realistic their assumption was that sand costs would increase by
the same pattern nationwide as they would in Florida.

Results

     Loss of Wetlands and Dryland

     Table 9-4 illustrates 95% confidence intervals for the
nationwide losses of wetlands and dryland.  If all shorelines

                               9-33

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Table 9-4.
                                       Sea Level Rise

Nationwide Loss of Wetlands and Drylands
Souare Miles (%)

Wetlands
Total protection
Standard
protection
No protection
Baseline

N.C.
1168-3341
(9-25)
N.C.
50 cm

4944-8077
(38-61)
2591-5934
(20-45)
2216-5592
(17-43)
100 cm

6503-10843
(50-82)
3813-9068
(29-69)
3388-8703
(26-66)
200cm

8653-11843
(66-90)
4350-10995
(33-80)
3758-10025
(29-76)
Drylands

Total protection

Standard
 protection

No protection
                      00             0

                   2180-6147   4136-9186    6438-13496


                   3315-7311   5123-10330   8791-15394
N.C. = Not Calculated

Source:  Titus and Greene, Volume 	.
                                  9-34

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Chapter 9

were protected, a 1-m rise would result in a loss of 50-82% of
U.S. coastal wetlands, and a 2-m rise would result in a loss of
66-90%.  If only the densely developed areas are protected, the
losses would be 29-69% and 61-80% for the 1- and 2-m scenarios,
respectively.  Except for the Northeast, no protection results in
only slightly lower wetland loss than protecting only densely
developed areas.  Although the estimates for the Northeast,
mid-Atlantic, the Gulf regions outside Louisiana, and the Florida
peninsula are not statistically significant (at the 95%
confidence levels), results suggest that wetland loss would be
least in the Northeast and Northwest.

     Costs of Holding Back the Sea

     Table 9-5 illustrates the Titus and Greene estimates of the
costs of holding back the sea.  The low range for the sand costs
is based on Leatherman's study, and the high range is based on
the increasing cost scenario Titus and Greene developed.  The
uncertainty -range for the costs of elevating structures reflects
the uncertainty in census data regarding the current density of
development.  High and low estimates for the cost of protecting
sheltered shorelines are based on the sampling errors of the
estimates for the 46 sites that both Park et al. and Weggel et
al. examined.

     Titus and Greene estimated that the cumulative nationwide
cost of  protecting currently developed areas in the face of a 1-
m rise would be from $73 to 111 billion, with costs for the 50-
and 200-cm scenarios ranging from $32 to 309 billion.
POLICY IMPLICATIONS

Wetland Protection

     The nationwide analysis showed that a 50- to 200-cm rise in
sea level could reduce the coastal wetland acreage (outside
Louisiana) by 17-76% if no mainland areas are protected, by
20-80% if only currently developed areas are protected, and by
38-90% if all mainland areas are protected.  These estimates of
the areal losses understate the differences in impacts for the
various land-use options.  Although a substantial loss would
occur even with no protection, most of today's wetland shorelines
still would have wetlands; the strip simply would be narrower.
By contrast, protecting all mainland areas would generally
replace natural shorelines with bulkheads and levees.  This
distinction is important because for many species of fish, the
length of a wetland shoreline is more critical than the total
area.
                               9-35

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Table 9-5.
                                       Sea Level Rise

Cumulative Nationwide Cost of Protecting Barrier
Islands and Developed Mainland Through the Year 2100
(billions of dollars)

Open Coast
Sand
Raise houses,
roads, utils
Sheltered shores
Total*
Source: Titus and
Sea
50 cm

15-20
9-13
5-13
32-43
Greene (Volume
Level Scenario
100 cm

27-41
21-57
11-33
73-111
).

200 cm

58-100
75-115
30-101
119-309

*Note:  Range for totals are based on the square root of the sum
of squared ranges.
                               9-36

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Chapter 9

Options for State and Local Governments

     Titus  (1986) examined three approaches for maintaining
wetland shorelines in the face of a rising sea: (1) no further
development in lowlands;  (2) no action now but a gradual
abandonment of lowlands as sea level rises; and (3) allowing
future development only with a binding agreement to allow such
development to revert to nature if it is threatened by
inundation.

     The first option would encounter legal or financial hurdles.
The extent to which the "due-process" clause of the Constitution
would allow governments to prevent development in anticipation of
sea level rise has not been specifically addressed by the courts.
Although purchases of land would be feasible for parks and
refuges, the cost of buying the majority of lowlands would be
prohibitive.  Moreover, this approach requires preparation for a
rise in sea level of a given magnitude; if and when the sea rises
beyond that point, the wetlands would be lost.  Finally,
preventing future development would not solve the loss of
wetlands resulting from areas that have already been developed.

     Enacting no policy today and addressing the issue as sea
level rises would avoid the costs of planning for the wrong
amount of sea level rise but would probably result in less
wetland protection.  People are developing coastal property on
the assumption that they can use the land indefinitely.  It would
be difficult for any level of government to tell property owners
that they must abandon their land with only a few years' notice,
and the cost of purchasing developed areas would be even greater
than the cost of buying undeveloped areas.

     Economic theory suggests that under the third alternative,
people would develop a property only if the temporary use
provided benefits greater than the costs of writing it off early.
This approach would result in the greatest degree of flexibility,
because it would allow real estate markets to incorporate sea
level rise and to determine the most efficient use of land as
long as it remains dry.

     This approach could be implemented by regulations that
prohibit construction of bulkheads as sea level rises or by the
use of conditional long-term leases that expire when high tide
falls above a property's elevation.

     Maine (1987) has implemented this third approach through its
coastal dune regulations,  which state that people building houses
along the shore should assume that they will have to move their
houses if their presence prevents the natural migration of
coastal wetlands, dunes, or other natural shorelines.   A number

                              9-37

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                                                   Sea Level Rise

of States also have regulations that discourage bulkheads,
although they do not specifically address sea level rise.  The
option can be implemented through cooperative arrangements
between developers, conservancy groups,  and local governments.
(See Titus and Greene for additional details.)

The Federal Role

     Section 404 of the Clean Water Act discourages development
of existing wetlands, but it does not address development of
areas that might one day be necessary for wetland migration.
This program will provide lasting benefits, even if most coastal
wetlands are inundated.  Although marshes and swamps would be
inundated, the shallow waters that formed could provide habitat
for fish and submerged aquatic vegetation.  No one has assessed
the need for a Federal program to protect wetlands in the face of
rising sea level.

Coastal Protection

State and Local Efforts

     State and local governments currently decide which areas
would be protected and which would be allowed to erode.
Currently, few localities contribute more than 10% of the cost of
beach nourishment, with the States taking on an increasing share
from the Federal Government.  However, if global warming
increases the costs of coastal protection over the next century
by $50-300 billion, many coastal officials doubt that their
States could raise the necessary funds.   If State funds could not
be found, the communities themselves would have to take on the
necessary expenditures or adapt to erosion.

     Long Beach Island, New Jersey, illustrates the potential
difficulties.  The annual cost of raising the island would
average $200-1,000 per house over the next century (Titus and
Greene, Volume 	1).  Although this amount is less than one
week's rent during the summer, it would more than double property
taxes, an action that is difficult for local governments to
contemplate.  Moreover, the island is divided among six
jurisdictions, all of which would have to participate.

     More lightly developed communities may decide that the
benefits of holding back the sea are not worthwhile.   Sand costs
would be much less for an island that migrated.  Although Weggel
estimated that higher costs would be associated with allowing
Long Beach Island to migrate landward than with raising the
island in place, this conclusion resulted largely from the cost
of rebuilding sewers and other utilities that would still be
useful if the island were raised.

                               9-38

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Chapter 9

     Regardless of how a barrier island community intends to
respond to sea level rise, the eventual costs can be reduced by
deciding on a response well in advance.  The cost of raising an
island can be reduced if roads and utilities are routinely
elevated or if they have to be rebuilt for other reasons (e.g.,
Titus et al., 1987).  The cost of a landward migration also can
be reduced by discouraging reconstruction of oceanfront houses
destroyed by storms (Titus et al., 1984a).  The ability to fund
the required measures also would be increased by fostering the
necessary public debate well before the funds are needed.

Federal Efforts

     While State governments generally are responsible for
protecting recreational beaches, the U.S. Army Corps of Engineers
is responsible for several major Federal projects to rebuild
beaches and for efforts to curtail land loss in Louisiana.   The
long-term success of these efforts would be improved if the Corps
were authorized to develop comprehensive long-term plans to
address the impacts of sea level rise.

     Beach Erosion

     In its erosion-control efforts, the Corps has recently
shifted its focus from hard structures (e.g., seawalls,
bulkheads, and groins) to soft approaches, such as pumping sand
onto beaches.  This shift is consistent with the implications of
sea level rise: groins and seawalls will not prevent loss of
beaches due to sea level rise.  Although more sand will have to
be pumped than current analyses suggest,  this approach clearly
could ensure the survival of the nation's beaches.

     Nevertheless, consideration of accelerated sea level rise
would change the cost-benefit ratios of many Corps erosion
control projects.  As with the operations of reservoirs
(discussed in Chapter 6:  Southeast),  the Corps is authorized to
consider flood protection but not recreation.  When they
evaluated the benefits of erosion control at Ocean City,
Maryland, the Corps concluded that less than 10% of the benefits
would be for flood control (most were related to recreation).
Had they considered accelerated sea level rise, however, the
estimated flood protection benefits from having a protective
beach would have constituted a considerably higher fraction of
the total benefits (Titus, 1985).

     Wetland Loss in Louisiana

     By preventing freshwater and sediment from reaching the
coastal wetlands, Federal management of the Mississippi River is
increasing the vulnerability of coastal Louisiana to a sea level

                               9-39

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                                                   Sea Level Rise

rise (e.g., Houck, 1983).  For example, current navigation
routes require the Corps of Engineers to limit the amount of
water flowing through the Atchafalaya River and to close natural
breaches in the main channel of the Mississippi; these actions
limit the amount of freshwater and sediment reaching the
wetlands. Alternative routes have been proposed that would enable
water and sediment to reach the wetlands  (Louisiana Wetland
Protection Panel, 1987).  These include dredging additional
canals parallel to the existing Mississippi River gulf outlet or
constructing a deepwater port east of the city.

     Either of these options would cost a few billion dollars.
By contrast, annual resources for correcting land loss in
Louisiana have been in the tens of millions of dollars.  As a
result, mitigation activities have focused on freshwater
diversion structures and on other strategies that can reduce
current wetland loss attributable to high salinities but that
would not substantially reduce wetland loss if sea level rises
50-200 cm (Louisiana Wetland Protection Panel, 1987) .

     The prospect of even a 50 cm rise in sea level suggests the
solving the Louisiana wetland loss problem is much more urgent
than is commonly assumed.  Because federal activities are now a
major cause of land loss, and would have to be modified to enable
wetlands to survive a rising sea, the problem is unlikely to be
solved without a Congressional mandate.  A recent interagency
report concluded that "no one has systematically determined what
must be done to save 10, 25, or 50 percent of Louisiana's coastal
ecosystem."  (Louisiana Wetland Protection Panel, 1988).  Until
someone estimates the costs and likely results of strategies with
a chance of protecting a significant fraction of the wetlands in
face of rising sea level, it will be difficult for Congress to
devise a long-term solution.

     Flood Insurance

     In 1968, Congress created the National Flood Insurance
Program with the objective of reducing Federal disaster relief
resulting from floods.  The Federal Emergency Management Agency
(FEMA), which already was responsible for administering disaster
relief, was placed in charge of this program as well.

     The National Flood Insurance Program sought to offer
localities an incentive to prevent flood-prone construction.  In
return for  requiring that any construction in a floodplain be
designed to withstand a 100-year flood, the federal government
would provide subsidized insurance to existing homes and a
fair-market rate for any new construction (which was itself a
benefit, since private insurers generally did not offer flood
insurance).  Moreover, as long as a community joined the program,

                               9-40

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Chapter 9

it would continue to be eligible for federal disaster relief; if
it did not join, it would no longer be eligible.  As a result of
this program, new coastal houses are generally elevated on
pilings.

     Although Congress intended to prevent coastal disasters, the
National Flood Insurance Act does not require strategic
assessments of long-term issues (see Riebsame, Volume _).  Thus,
FEMA has not conducted strategic assessments of how the program
could be managed to minimize flood damage from shoreline retreat
caused by both present' and future rates of sea level rise.

     Congress recently enacted the Upton-Jones Amendment  (Public
Housing Act of 1988), which commits the federal government to pay
for rebuilding or relocating houses that are about to erode into
the sea.  Although the cost of this provision is modest today, a
sea level rise could commit the federal Government to purchase
the houses on all barrier islands that did not choose to hold
back the sea.  Furthermore, this commitment could increase the
number of communities that decided not to hold back the sea.

     The planned implementation of actuarially sound insurance
rates would ensure that as sea level rise increased property
risk, insurance rates would rise to reflect the risk.  This would
discourage construction of vulnerable houses, unless their value
was great enough to outweigh the likely damages from floods.
However, statutes limiting the rate at which flood insurance
rates can increase could keep rates from rising as rapidly as the
risk of flooding, thereby increasing the federal subsidy.

     No assessment of the impacts of sea level rise on the
federal flood insurance program has been undertaken.

Sewers and Drains

     Sea level rise also would have important impacts on coastal
sewage and drainage systems.   Wilcoxen (1986) examined the
implications of the failure to consider accelerated sea level
rise in the design of San Francisco's West Side (sewerage)
Transport,  a large steel-reinforced concrete box buried under
the city's ocean beach.   He found that beach erosion will
gradually expose the transport to the ocean.  Although the
structure probably could withstand wave attack,  it would act as a
seawall and eventually result in loss of the recreational beach
or necessitate shore-protection projects that, over the course of
a century,  would cost more than the project itself.  Wilcoxen
concludes that had sea level  rise been considered, the project
probably would have been sited elsewhere.
                               9-41

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                                                   Sea Level Rise

     The impacts of sea level rise on the construction grants
program probably would be less in most other cases.  As sea level
rises, larger pumps would be necessary to transport effluents
from settling ponds to the adjacent body of water.  However,
sea level rise would not necessarily require alternative siting.
The projects serving barrier islands often are located on the
mainland, and projects located on barrier islands are generally
elevated well above flood levels.  If barrier islands are raised
in response to sea level as the nationwide analysis suggests,
sewerage treatment plants will be a small part of the
infrastructure that has to be modified.

     Engineering assessments have concluded that it is already
cost-beneficial to consider sea level rise in the construction of
coastal drainage systems in urban areas.  For example, the extra
cost of installing the larger pipes necessary to accommodate a
1-foot rise in sea level would add less than 10% to the cost of
rebuilding a drainage system in Charleston, South Carolina;
however, failure to consider sea level rise would require
premature rebuilding of the $4 million system (Titus et al.,
1987).

RESEARCH NEEDS

     A much better understanding of erosion processes is needed
1) to understand how much erosion will take place if no action is
taken; and 2) to help identify the most cost-effective means for
protecting sandy shores.  An improved understanding of how
wetland accretion responds to different temperatures, higher CO2
concentrations, changing mineral content, and the drowning of
adjacent wetlands is needed.  This will refine our ability to
project future wetland loss and, perhaps, devise measures for
artificially enhancing their vertical growth.

     This report did not examine the impacts of increased
flooding because flood models have not been applied to the large
numbers of coastal sites that would be necessary to conduct a
nationwide assessment.  Time dependant estuarine salinity models,
such as that of the Delaware River Basin Commission should be
applied to major estuaries for examining impacts on ecosystems
and drinking water supplies.

     Assessments of the impacts of global warming on coastal
environments would be greatly improved by better estimates of
future sea level rise.  In addition to the improved ocean
modelling that will be necessary for better projections of
surface air temperatures (see Chapter 2: Global Climate Change),
this will also require a substantial increase in the resources
allocated for monitoring and modelling glacial processes.
Finally, this report assumed that winds, waves,  and storms

                               9-42
                                                                    I

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Chapter 9

remained constant; future studies will need estimates of the
changes in these climatic variables.
                              9-43

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                                                   Sea Level Rise

REFERENCES

Armentano, T.V.,  R.A. Park, and C.L. Cloonan.  1988.  Impacts on
coastal wetlands throughout the United States.  In: Titus, J.G.
ed.   Greenhouse Effect, Sea Level Rise, and Coastal Wetlands.
Washington, DC:  EPA.

Barnett, T.P.  1984.  The estimation of "global" sea level
change:  a problem of uniqueness.  Journal of Geophysical
Research  89(C5):7980-7988.

Earth, M.C., and J.G. Titus, eds.  1984.  Greenhouse Effect and
Sea Level Rise:  A challenge for this generation.  New York:  Van
Nostrand Reinhold.

Bentley, C.R.  1983.  West Antarctic ice sheets:  diagnosis and
prognosis.  In: Proceedings of the Carbon Dioxide Research
Conference:  Carbon Dioxide, Science, and Consensus. Conference
820970.  Washington, DC:  Department of Energy.

Bruun, P.  1962.   Sea level rise as a cause of shore erosion.
Journal of Waterways and Harbors Division  (ASCE) 1:116-130.

Dean, R.G. et al. 1987.  Responding to Changes in Sea Level.
Washington, DC: National Academy Press.

Dony, W.L., W.R.  Farrand, and M. Ewing.  1962.  Pleistocene ice
volumes and sea level lowering.  Journal of Geology 70:206-214.

Everts, C.H.  1985.  Effect of sea level rise and net sand volume
change on shoreline position at Ocean City, Maryland.  In: Titus,
J.G., ed.  Potential Impact of Sea Level Rise on the Beach at
Ocean City, Maryland.  Washington, DC:  U.S.  Environmental
Protection Agency.

Fairbridge, R.W., and W.S. Krebs Jr.  1962.  Sea level and the
southern oscillation.  Geophysical Journal  6:532-545.

Gibbs, M.  1984.   Economic analysis of sea level rise:  methods
and results.  In: Earth, M.C., and J.G. Titus, eds.  Greenhouse
Effect and Sea Level Rise:  A challenge for this generation.  New
York:  Van Nostrand Reinhold.

Gornitz, V.S., S. Lebedeff, and J. Hansen.  1982.  Global sea
level trend in the past century.  Science  215:1611-1614.

Hoffman, J.S., D. Keyes, and J.G. Titus.  1983.  Projecting
Future Sea Level Rise.  Washington, DC: U.S.  Environmental
Protection Agency.
                               9-44
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Chapter 9
Hoffman, J.S., J. Wells, and J.G. Titus.  1986.  Future global
warming and sea level rise.  In: Sigbjarnarson, G., ed.  Iceland
Coastal and River Symposium.  Regkjavik/Iceland:  National Energy
Authority.

Houck, O.A.  1983.  Land loss in coastal Louisiana:  causes,
consequences, and remedies.  Tulane Law Review 58(1):3-168.

Howard, J.D., O.H. Pilkey, and A. Kaufman.  1985.  Strategy for
beach preservation proposed.  Geotimes.  30(12):15-19.

Hughes, T.  1983.  The stability of the West Antarctic Ice Sheet:
What has happened and what will happen.  In:  Proceedings of the
carbon Dioxide Research Conference:  Carbon Dioxide, Science, and
Consensus. Conference 820970.  Washington, DC:  Department of
Energy.

Hull, C.H.J., and J.G. Titus.  1986.  Responses to salinity
increases.  In:  Hull, C.H.J., and J.G. Titus.  1986.  Greenhouse
Effect, Sea Level Rise, and Salinity in the Delaware Estuary.
Washington, DC:  U.S. Environmental Protection Agency and
Delaware River Basin Commission.

Hull, C.H.J., and J.G. Titus.  1986.  Greenhouse Effect, Sea
Level Rise, and Salinity in the Delaware Estuary.  Washington,
DC:  U.S. Environmental Protection Agency and Delaware River
Basin Commission.

Kana, T.W., J. Michel, M.O. Hayes, and J.R. Jensen.  1984.  The
physical impact of sea level rise in the area of Charleston,
South Carolina.  In: Earth, M.C., and J.G. Titus, eds.
Greenhouse Effect and Sea Level Rise:  A challenge for this
generation.  New York:  Van Nostrand Reinhold.

Kennett. 1982.  Marine Geology.  Englewood Cliffs, N.J:
Prentice-Hall.

Kyper, T., and R. Sorenson.  1985.  Potential impacts of sea
level rise on the beach and coastal structures at Sea Bright, New
Jersey.  In: O.T. Magson, ed.  Coastal Zone '85.  New York:
ASCE.

Leatherman, S.P.  1984.  Coastal geomorphic responses to sea
level rise:  Galveston Bay, Texas.  In: Earth, M.C., and J.G.
Titus, eds.  Greenhouse Effect and Sea Level Rise:  A challenge
for this generation.  New York:  Van Nostrand Reinhold.
                               9-45

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                                                   Sea Level Rise

Lyle et al.  1987.  Sea Level Variations in the United States
Rockville, MD:  National Ocean Service.

Maine, State of.  1987.  Dune Rule 355. August 9:  Maine
Department of Environmental Protection.

Meier, M.F. et al.  1985.  Glaciers, Ice Sheets, and Sea Level.
Washington, DC:  National Academy Press.

Meier, M.F.  1984.  Contribution of small glaciers to global sea
level.  Science  226(4681):1418-1421.

Mercfer, J.H.  1968.  Antarctic ice and Sangamon sea level.
Geological Society of America Bulletin  79:471.

Oldale, R.  1985.  Late quaternary sea level history of New
England:  a review of published sea level data.  Northeastern
Geology  7:192-200.

Revelle, R.  1983.  Probable future changes in sea level
resulting from increased atmospheric carbon dioxide.  In Changing
Climate.  Washington, DC:  National Academy Press.

Schelling, T.  1983.  In: Changing Climate.  Washington, DC:
National Academy Press.

Sorensen, R.M., R.N. Weisman, and G.P. Lennon.  1984,  Control of
erosion, inundation, and salinity intrusion.  In: Earth, M.C.,
and J.G. Titus, eds.  Greenhouse Effect and Sea Level Rise:  A
challenge for this generation.  New York:  Van Nostrand Reinhold.

Thomas, R.H.  1986.  In: Titus, J.G., ed.  Effects of Changes in
Stratosphere Ozone and Global Climate.  Washington, DC:  U.S.EPA
and UNEP.

Thomas, R.H.  1985.  Responses of the polar ice sheets to
climatic warming.  In:  Meier, M.F. et al. Glaciers, Ice Sheets,
and Sea Level.  Washington, DC:  National Academy Press.

Titus, J.G.  1988.  Sea Level Rise and Wetlands Loss:  An
Overview.  In: Titus, J.G. (ed).  Greenhouse Effect, Sea Level
Rise, and Coastal Wetlands.  Washington, DC:  U.S. Environmental
Protection Agency.

Titus, J.G., ed.  1988.  Greenhouse Effect, Sea Level Rise, and
Coastal Wetlands.  Washington, DC:  U.S. Environmental Protection
Agency.
                               9-46

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Chapter 9

Titus, J.G.  1987.  The Greenhouse Effects, Rising Sea Level, and
Society's Response.  In:  Devoy, R.J.N.   Sea Surface Studies.
New York:  Groom Helm.

Titus, J.G.  1986.  Greenhouse effect, sea level rise, and
coastal zone management.  Coastal Zone Management Journal
14:3:147-171.

Titus, J.G.  1985.  Sea level rise and the Maryland coast.  In
Potential impacts of sea level rise on the beach at Ocean City,
Maryland.  Washington, DC:  U.S. Environmental Protection Agency.

Titus, J.G.  1984.  Planning for sea level rise before and after
a coastal disaster.  In: Earth, M.C., and J.G. Titus, eds.
Greenhouse Effect and Sea Level Rise:  A challenge for this
generation.  New York:  Van Nostrand Reinhold.

Titus, J.G., M.C. Barth, J.S. Hoffman, M. Gibbs, and M. Kenney.
1984.  An overview of the causes and effects of sea level rise.
In: Barth, M.C., and J.G. Titus, eds.  Greenhouse Effect and Sea
Level Rise:  A challenge for this generation.  New York:  Van
Nostrand Reinhold.

Titus, J.G., T. Henderson, and J.M. Teal.  1984.  Sea level rise
and wetlands loss in the United States.  National Wetlands
Newsletter Environmental Law Institute  6:4.

Titus, J.G., C.Y. Kuo, M.J. Gibbs, T.B. LaRoche, M.K. Webb, and
J.O. Waddell.  1987.  Greenhouse effect, sea level rise, and
coastal drainage systems.  Journal of Water Resources Planning
and Management.  ASCE 113(2):216-227.

Wilcoxen, P.J.  1986.  Coastal erosion and sea level rise:
implications for ocean beach and San Francisco's westside
transport project.  Coastal Zone Management Journal 14:3.
                               9-47

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                            CHAPTER 10

                           AGRICULTURE
FINDINGS

Although climate change is not likely to threaten U.S. food
supplies, it will affect crop yields and result in a northward
shift in cultivated land, causing significant regional
dislocations in agriculture with associated impacts on regional
economies.  It will expand crop irrigation requirements, stress
livestock production, and increase infestations of agricultural
pests and diseases.

Crop Yields

o    The effects of climate change alone may reduce average
     yields of corn, soybeans, and wheat, both rainfed and
     irrigated, except in the northernmost latitudes where warmer
     conditions provide a longer frost-free growing season.
     Decreases in modeled yields result primarily from higher
     temperatures, which shorten a crop's life cycle.

o    When the direct effects of C02  on  crop  photosynthesis  and
     transpiration are approximated along with the effects of
     climate change, average rainfed and irrigated corn,
     soybeans, and wheat yields could overcome the negative
     effects of climate change in some locations.  If climate
     changes are severe, yields could decline.  Whether these
     modeled results will be reproduced under field conditions is
     uncertain.

o    Even if the patterns of climate variability are unchanged,
     yield stability may decrease, particularly under rainfed
     conditions.  This may occur because there would be more days
     above temperature thresholds for particular crops.  The
     exact magnitude of change will be sensitive to changes in
     climatic variability.

Economic Impacts

o    There may be a small to moderate aggregate reduction in the
     nation's agricultural output.  Production appears to be
     adequate to meet domestic consumption needs.

o    Assuming no change in export demand, reduced outputs would
     decrease exports,  which could negatively affect global food
     supplies and the U.S. trade balance.  This report did not
     analyze global changes in agriculture.

                               10-1

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                                                      Agriculture   ^
o    Under the most severe climate change scenarios, continued
     technological improvements, similar to those in recent
     years, would have to be sustained to offset losses.

o    The economic response of agriculture to shifts in regional
     productivity may be to shift crop production and associated
     infrastructure in a northward direction.  It is not possible
     to determine if corn and soybean production could be
     sustained in northern areas, because soil conditions and
     other factors were not analyzed.

Irrigation Demand

o    The demand for irrigated acreage is likely to increase in
     all regions.  This is due to the reliability of irrigated
     yields relative to dryland yields and to higher commodity
     prices that make expansion of irrigated production more
     economically feasible.  This result is sensitive to whether
     the cost of water to farmers increases.

o    More irrigation may increase stress on and competition for
     regional water supplies.  Increased irrigation also implies
     associated increases in surface and groundwater pollution
     and other forms of environmental degradation.

Agricultural Pests

o    Climate warming could change the ranges and populations of
     agricultural pests.  Temperature increases may enhance the
     survival of insect pests in the winter, extend their
     northward ranges, increase pest species with more than one
     generation per year, and allow pest establishment earlier in
     the growing season.  These effects could result in a
     substantial rise in pesticide use, with accompanying
     environmental hazards.

Farm-Level Adjustments

o    Farmers may adjust to climate change by using full-season
     and heat-resistant crop species or varieties, by altering
     planting dates, by planting two crops during one growing
     season, by increasing or altering their scheduling of
     irrigation, by using more pesticides, and by harvesting
     earlier.  If climate change is not severe, these adjustments
     may mitigate losses in crop yields; more severe climate
     change is likely to make major adaptation necessary.
                              10-2

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Chapter 10

Livestock Effects

o    Higher temperatures may increase disease and heat stress on
     livestock in some regions.  Existing livestock diseases may
     shift north, while tropical diseases may extend their ranges
     into southern regions of the United States.  Cold stress
     conditions may be reduced in the winter, but heat stress is
     likely to increase in the summer.  Reproductive capabilities
     may also decrease.

Policy Implications

o    Global climate change has important implications for all
     parts of the agriculture system.  The agricultural research
     structure, which is dedicated to maintaining U.S. farm
     productivity, should enhance climate change research from
     the field level to the national policy level.

o    Current U.S. Department of Agriculture (USDA) research on
     heat- and drought-tolerant crops and practices should be
     sustained and, possibly, enhanced to limit vulnerability to
     future climate change.

o    The USDA should evaluate the implications of current
     legislation on the ability of agriculture to adapt to global
     warming by shifting the types of crops and location of
     farming.  Such adaptation strategies should consider the
     impacts of soil erosion and water quality.

o    The USDA, the Department of Commerce, the U.S. Trade
     Representative, and the State Department should consider the
     implications of potential long-term changes in the level of
     U.S. crop exports for the U.S. balance of trade and
     strategic interests.

o    There is an urgent need for a national drought policy to
     coordinate Federal response to the possibility of increased
     frequency and duration of future droughts.  Even without
     climate change, such a policy is needed not only for the
     agricultural sector, but also for other sectors.


SENSITIVITY OF AGRICULTURE TO CHANGES IN CLIMATE

     Agriculture is a critical American industry,  providing food
for the nation's population and as much as $42.6 billion in
exports for the nation's trade balance (Figure 10-1).  The
industry employs 21 million people — more than other industry,
when taking into account workers on farms and in the meat,

                               10-3

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   Billions of $
    50
E23 Others
CD Fruits, nuts and vegetables
S3 Cotton
E3 Livestock end products
(Z3 Oilseeds end products
•I Grains and preparations
           72  73  74  75   76  77  78  79  80  81  82  83  84  85  86
Figure  10-1.   Value of  U.S. agricultural exports  by commodity.

Sources:   The World Food Institute  and U.S. Department of
Agriculture,  Economic Research Service, Foreign Agricultural
Trade of  the United States (Washington, DC), January-February
1987 and  various other  issues.  Livestock excludes poultry  and
dairy products.
                                 10-4

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Chapter 10

poultry, dairy, baking, and food processing industries  (Council
for Agricultural Science and Technology, 1988).  The U.S.
agricultural production system includes farm equipment
manufacture, fertilizer and seed supplies, rural banking, and
shipping.  Total farm assets were $771 billion in 1985; food and
fiber were 17.5% of the total gross national product in the same
year.  Wheat, corn, soybeans, cotton, fruits and vegetables, and
livestock are among the most important U.S. agricultural
commodities.

     The study areas are major agricultural production regions
(see Table 10-1).  The Great Lakes and Southeastern States are
major corn and soybean producers, while the Great Plains States
grow mainly wheat and corn.

     Worldwide, agricultural products must provide sustenance for
the world's growing population, now estimated at about 5 billion
and projected to rise to 8.2 billion by 2025 (World Bank, 1988).
Global production and consumption of grain have grown steadily
since 1960, although regional food shortages continue to occur
due to climate variability and socioeconomic factors.
Technological advances, such as improved hybrids and irrigation
systems, have reduced the dependence of crop yields on the
natural environment, but weather is still an important factor in
agricultural productivity.

     For example, during the Dust Bowl years of the 1930s, wheat
and corn yields dropped by up to 50%.  Midsummer 1983 saw an
unpredicted drought in the U.S. Corn Belt and in the southeastern
United States, causing the U.S. corn yields to fall by about a
third, from over 7,000 kg/hectare (ha) to about 5,000 kg/ha.  And
failure of the monsoon season caused shortfalls in crop
production in India, Bangladesh, and Pakistan in 1987.  The 1980s
have also seen the continued deterioration of food production in
Africa, despite adequate world food supplies elsewhere, because
of persistent drought, internal wars, poor distribution, weak
infrastructure, and a deteriorating environment.

     The 1988 drought demonstrated the impact that climate
variability can have on agricultural productivity.  This drought
is expected to decrease corn yields by about 40%, and the cost of
the 1988 Drought Relief Bill is estimated to be $3.9 billion (New
York Times, 1988).  The 1988 drought emphasizes anew the close
link between agriculture and climate and the need to consider
broadly the impacts of potential climate change on U.S.
agriculture.

     Future changes in climate due to increasing atmospheric
trace gases, particularly C02,  will  affect  agriculture because

                               10-5

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                 Table  10-1.   Crop  Data by Region
                                                      Agriculture
                     Corn
Wheat
             Harvested
               Acres
Soybeans    (thousands)
EPA Study Areas
Southeast
Great Lakes
Great Plains
California
Total (48 States)

311
4,644
921
38
8,209

272
297
755
63
2,507

306
822
136
• o.oi
199

29
92
71
6
337
Units:    Corn, wheat, and soybeans are in thousands of bushels;
          harvested acres are also in thousands.

Source:   1982 Census of Agriculture, Vol. 1, Geographical Area
          Series, Part 51, United States Summary and State Data.
          U.S. Department of Commerce, Bureau of the Census.
                               10-6

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Chapter 10


light from the sun,  frost-free growing seasons, and the
hydrologic cycle largely govern crop productivity.  Livestock
production will also respond to climate change through differing
levels of heat and cold stress and altered ranges of disease-
carrying vectors such as mosquitoes and ticks.  Sea level rise,
an associated impact of climate change, will threaten low-lying
coastal agricultural regions with seasonal, and in some instances
permanent, flooding, saltwater intrusion of freshwater aquifers
and rivers, and salt contamination of soils.  (See Water
Resources chapter in this volume for linkages with agriculture.)

     As predicted rises in temperature and other changes in
climate variables such as precipitation occur, the higher levels
of CO2 in the air will also affect crops.   Increasing C02 has
boosted crop photosynthesis and has reduced the use of water by
crops in experimental settings.  Because experimental research
has rarely dealt with both the climatic and the direct effects of
CO2 on plants simultaneously,  it is difficult to assess the
relative contributions of C02 and increased temperature to plant
responses.  This remains one of the most crucial questions in the
analysis of impacts  of climate change and increased CO2 on
agriculture.

     Associated processes, such as changes in agricultural pests,
may also play a role in responses of U.S. agriculture to climate
change.  The presence and abundance of pests affecting both crops
and livestock are highly dependent on climate.  The severity of
the winter season, wind patterns, and moisture conditions
determine in large part where pests will be prevalent.  As these
conditions change, the patterns, numbers, and types of insects
also will change.

     Much of U.S. agricultural production takes place under
technologically advanced cropping systems that are primarily
monocultural.  Likewise, livestock production is highly
specialized, both technically and geographically, and a high
degree of integration exists between grain and livestock
production.  The economic robustness associated with general,
multiple-enterprise  farms has long since passed from the scene on
any significant scale.  Thus, the current vulnerability of our
agricultural system  to climate change may be greater in some ways
than it was in the past.

     Climate change  and agriculture may affect the natural
environment.  As regional changes occur in crop and livestock
production, these changes in agriculture may increase soil
erosion, intensify the demand for water for irrigation, degrade
water quality, reduce forested land, and destroy wildlife

                               10-7

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                                                      Agriculture

habitats.  Other potential consequences are soil degradation,
groundwater overdraft, loss of plant and aquatic communities, and
reduced resilience in environmental resources in general.  (See
the Water Resources and Biological Diversity chapters of this
report.)

     Climate-driven changes in crop and livestock productivity
cause changes in profitability and decisionmaking at the farm
level, which in turn lead to shifts in farming systems at the
regional level and in export-import supply and demand at the
national level.  Ultimately, impacts of climate change will
reverberate throughout the global food economy, altering global
food trade.  Changes in U.S. agriculture will thus take place in
a global context.
PREVIOUS STUDIES OF THE EFFECTS OF CLIMATE CHANGE AND AGRICULTURE

     Relationships between climate and agriculture have been
studied intensively for many years.  However, relatively few
studies have specifically addressed both the climatic and the
direct effects that the growth in trace gases will have on
agriculture.  Even fewer studies have addressed these potential
effects in an integrated approach that links both biophysical and
economic spheres of analysis.

     Most research attention in the United States has focused on
the direct effects of C02  on crops,  supported primarily by  the
U.S. Department of Energy.  These studies are reviewed by Acock
and Allen (1985) and Cure (1985) who found an average increase in
yields of about 30% and increases in water-use efficiency for
crops growing in favorable,  current climate conditions between
330 and 660 ppm C02.   Kimball (1985)  and  Decker et al.  (1985)
suggest that the potential effects of CO2 and/or climate change
on agricultural production systems may include shifts in
production areas and changes in levels of livestock stresses,
water availability, and pest control management.

     Integrated approaches to the impacts of climate change on
agriculture involving both biophysical and economic processes
have been considered in studies by Callaway et al. (1982),  the
Carbon Dioxide Assessment Committee (1983), Warrick et al.
(1986), and the Land Evaluation Group (1987).  A benchmark
international study on both the agronomic and economic effects of
climate change on agriculture was conducted by the International
Institute for Applied Systems Analysis (Parry et al., 1988).  No
study has as yet comprehensively examined the combined effects of
climate change and the direct effects of CO2 on U.S.  agriculture.
                               10-8

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Chapter 10


CLIMATE CHANGE STUDIES IN THIS REPORT

Structure of and Rationale for the Studies

     The agricultural studies in this report involve the
following research areas (see Table 10-2):  (1) crop growth and
yield, (2) regional and national agricultural economics,  (3)
demand for water for irrigation, (4) water quality, (5) pest-
plant interactions, (6) direct effects of CC>2  on crop  growth and
yield, (7) impacts of extreme events, (8) potential farm-level
adjustments, (9) livestock diseases, and (10)  agricultural
policy.  The following studies were performed for this report:

     Regional Studies

     o    Effects of Projected C0?-Induced Climatic Changes on
          Irrigation Water Requirements in the Great Plains
          States — Allen and Gichuki, Utah State University

     o    Climate Change Impacts upon Agriculture and Resources:
          A Case Study of California — Dudek, Environmental
          Defense Fund

     o    Farm-Level Adjustments by Illinois Corn Producers to
          Climatic Change — Easterling, Resources for the Future

     o    Impacts of Climate Change on the Fate of Agricultural
          Chemicals Across the USA Great Plains and Central
          Prairie — Johnson, Cooter, and Sladewski, University
          of Oklahoma

     o    Impact of Climate Change on Crop Yield in the
          Southeastern U.S.A; A Simulation Study — Peart, Jones,
          and Curry, University of Florida

     o    Effects of Global Climate Change on Agriculture:  Great
          Lakes Region — Ritchie,  Baer, and Chou, Michigan State
          University

     o    Potential Effects of Climate Change on Agricultural
          Production in the Great Plains:  A Simulation Study —
          Rosenzweig,  Goddard Space Flight Center/Columbia
          University
                               10-9

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  Chapter 10
Table 10-2.  Agriculture Projects for EPA Report to Congress on the Effects
             of Climate Change

Projects
Crop Production
Demand for
Irrigation Water
Water Quality
Pest/Plant
Interactions
Farm-Level
Management
Regional/National
Economics
Direct Effects
of C02
Livestock Pests &
Diseases
Climatic
Variability
Agricultural
Policy
Regional Studies

California
X

X




X

X






Southeast
X

X




X

X





Great
Lakes
X

X
X
X

X
X

X





Great
Plains
X

X
X



X

X





National
Study





1
4
i
X

X

X

X
X
                                  10-10

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Chapter 10

     National Studies

     o    The Economic Effects of Climate Change on U.S.
          Agriculture;  A Preliminary Assessment — Adams, Glyer,
          and McCarl, Oregon State University

     o    Analysis of Climate Variability in General Circulation
          Models — Mearns, Schneider, Thompson, and McDaniel,
          National Center for Atmospheric Research

     o    Direct Effects of Increasing CO? on Plants and Their
          Interactions with Indirect  (Climatic) Effects — Rose

     o    Potential Effects of Climatic Change on Plant-Pest
          Interactions — Stinner, Rodenhouse, Taylor, Hammond,
          Purrington, McCartney, and Barrett, Ohio Agricultural
          Research and Development Center

     o    Agricultural Policies for Climate Chancres Induced bv
          Greenhouse Gases — Schuh, University of Minnesota

     o    Changing Animal Disease Patterns Induced by the
          Greenhouse Effect — Stem, Mertz, Stryker, and Huppi,
          Tufts University

     o    Effect of Climatic Warming on Populations of the Horn
          Fly — Schmidtmann and Miller, Agricultural Research
          Service

     Production of corn, wheat, and soybeans is critical to the
economic well-being of the nation's farmers and the national
trade balance.  These crops make up about two-thirds of the total
U.S. agricultural acreage, and their economic value is equal to
that of all other crops combined.  These three crops were
selected for the modeling studies on the effects of climate
change on yields.

     The results from the regional studies of crop production
(not including California) , hydrological predictions from the
climate models, and an agricultural economics model were linked
in an integrated approach, to enable translation of the estimated
yield changes from the crop modeling studies and predicted
changes in water availability into economic consequences (see
Figure 10-2).  Such a coordinated analytical framework is
necessary to account for the effects of market forces on the
total agricultural sector, including livestock, and
                              10-11

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                 Trace Gases
                                   GCMs
                                 Climate
                                 Change
                             Crop Response
                                Models
                             Yield & ET
                         Predictions  by Crop
             Soil and  Water
             Resource  Availability
                                 Trade
                           Assumptions
                     \
                           Agro-Economic
                             Models
                                    I
Figure  10-2.
                         sconomic Consequences
                        Land Use and Irrigated/
                       Acreage Changes
Flow chart of model  interactions in EPA studies of
the effects of global climate change on U.S.
agriculture.
Source: Dudek (1987).
                            10-12

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Chapter 10

to evaluate the adequacy of the nation's resource base for
agricultural production under climate change.  Economic forces
may lead farmers to grow more crops in areas with relatively high
productivity and fewer crops in areas with relatively low
productivity.

     The studies of demand for irrigation water, water quality,
and farm-level adjustment were also linked with the integrated
modeling studies by common assumptions, sites, or outputs.
Because California grows a large and diverse number of crop
commodities, a simple approach was used to estimate crop yield
changes for the California case study based on heat, sunlight,
and photosynthetic response to C02.   These yield changes  were
then used in a model of agricultural land and water use in
California.  Several adjustment experiments were included to test
possible adaptation mechanisms, such as changes in planting dates
and crop varieties.

     The agricultural studies performed for this EPA report
explore the sensitivities of the different parts of the
agricultural system (shown in Table 10-1) to climate change
scenarios.  They are not meant to be predictions of what will
happen; rather, they aim to define ranges and magnitudes of the
potential responses as the systems are currently understood.


RESULTS OP AGRICULTURE STUDIES

Regional Crop Modeling Studies

Design of the Studies

     Widely validated crop growth models — CERES-Wheat and
CERES-Maize (Ritchie and Otter, 1985) and SOYGRO (Jones et al.,
1988)  — were used to simulate wheat, corn, and soybean yields at
selected geographically distributed locations within the Great
Lakes, the Southeast,  and the Great Plains.  California crop
yield changes were predicted separately by using an agroclimatic
index.  (See the regional chapters of this report for specific
results.)   The crop models simulated both dryland and irrigated
production systems.  The crop modeling approach allowed for
analysis of latitudinal gradients in changes in crop yields and
provided compatible results for each climate change scenario to
be used as input in the agricultural economics study.   (See
Ritchie et al., Peart et al., and Rosenzweig, Volume _.)

     The direct effects of C02  —  i.e.,  increased photosynthesis
and improved water-use efficiency — were included with the
climate change scenarios in some model runs to evaluate the

                              10-13

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                                                      Agriculture

combined effects.  The direct effects were approximated by
computing ratios of elevated CO2 to  ambient CO2 values for daily
photosynthesis and evapotranspiration rates (see Peart et al.,
Volume _).

Limitations

     Uncertainties in the crop modeling studies reside in climate
model predictions, locations of the climate stations (not always
in production centers),  crop growth models, and estimates of the
direct effects of C02.   In particular,  the  climate  change
scenarios did not include changes in climate variability, even
though changes in the frequencies of extreme events may
considerably affect crop yields.  Technology and cultivars were
assumed not to change from present conditions.

     The direct effects of C02 in the crop  modeling study results
may be overestimated for two reasons.  First,  experimental
results from controlled environments may show more positive
effects of C02 than  would actually occur in variable, windy,  and
pest-infested (weeds, insects, and diseases) field conditions.
Second, because other radiatively active trace gases, such as
methane (Cfy)  also are increasing, the equivalent warming of  a
doubled C02 climate  may  occur somewhat before  an  actual  doubling
of atmospheric C02.   A level  of 660  ppm CO2 was assumed for the
crop modeling experiments, while the C02 concentration  in 2060 is
estimated to be 555 ppm  (Hansen et al., 1988).

Results

     Climate change scenarios alone, without the direct effects
of CO2,  caused simulated yields of corn,  soybeans,  and wheat  to
decrease in the Great Lakes,  Southeast, and Great Plains regions,
except in the northernmost latitudes, where warmer conditions
provide a longer frost-free growing season (Figure 10-3).  The
northern locations where yields increased included sites in
Minnesota.  Decreases in modeled yields resulted primarily from
higher temperatures, which shorten the crop life cycle thus
curtailing the production of usable biomass.  Dryland modeled
yields decreased more than irrigated yields.

     When increased photosynthesis and decreased transpiration
were included in the crop models along with the climate change
scenarios, yields increased over the baseline in some locations
but not in others (Figure 10-4).  Particularly when combined with
the hotter and drier GFDL climate change scenario,  the direct
effects of C02 did not fully  compensate for changes in climate
variables — net yields decreased significantly from the base
case.

                              10-14

-------
            Change  in Dryland Soybean Yield
                     GISS Climate Change Effects Alone
     X Change
                   25 TO 50
                      -25 TO  0
                      NOT MODELED
0 TO  25
Figure 10-3.
Percent change in rainfed soybean yields simulated
by the SOYGRO model with the GISS climate change
scenario.
Source:  Peart et al.  and Ritchie et al., Volume

                              10-15

-------
              °7
              so
                 Change in  Dryland Corn Yield
                       GFDL Climate and Direct C02 Effects
       X Change
                      0 TO  30
                                       -60 TO -30
                                       NOT MODELED
                                                       -30 TO
Figure 10-4 .
              Percent change in rainfed corn yields simulated by
              the CERES-Maize model for the GISS climate change
              scenario vith approximated direct effects of C02  on
              photosynthesis and water use.
Source:   Peart  et al. and Ritchie et al., Volume _ .
                               10-16

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Chapter 10

     The crop models were also used to test several possible
adaptations by farmers to the predicted climate changes.  For
example, a corn variety that is better adapted to longer growing
seasons was tested in Indiana.  This later maturing variety did
not compensate entirely for the yield decreases caused by the
warmer climate change scenarios.

Implications

     An implication of the crop modeling studies is that pressure
for increased irrigation may grow in many agricultural regions.
If the major agricultural areas are to continue to provide a
stable supply of food under the predicted changes in climate,
supplemental irrigation may be required for many soils.  This
could further tighten water supply problems in some areas and
increase pollution from nonpoint sources (i.e., pollution that is
not traceable to any one distinct source, such as agricultural
pollution).

     The water supply for the irrigation needed to stabilize
production would come from both surface and subsurface sources,
depending on the region.  However, considerable uncertainty
exists regarding the future availability of surface water and
groundwater supplies with climate change, and concerning the
costs of using or extracting the water.  (See the Water Resources
chapter of this report.)

Regional and National Economics Study

     The estimated yield changes from the crop modeling studies
and projected changes in irrigation water demand and availability
were introduced into an agricultural economic model to translate
the physical effects of climate change into economic
consequences.  Adams et al. (see Volume _)  estimated the regional
and national economic implications of changes in yields of wheat,
corn,  soybeans,  and other crops and in the demand for and
availability of water associated with alternative global climate
change scenarios.   In addition,  sensitivity analyses on critical
assumptions were also performed — particularly for technological
change and yield benefits due to the direct effects of increased
C02.

Study Design

     A spatial equilibrium agricultural model developed by Adams
et al. (1984) was used to represent production and consumption of
numerous agricultural commodities for the U.S. farm production
regions as designated by the USDA (see Figure 10-5).   The model
has been used to estimate agricultural losses due to increased

                              10-17

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Figure 10-5.   Farm production regions in the United States,



Source:  USDA Economic Research Service (1987) .



                              10-18

-------
Chapter 10


ultraviolet-B  (UV-B) radiation caused by stratospheric ozone
depletion  (Adams et al., 1984).  It consists of farm-level models
for production regions, integrated with a national-level model of
the agricultural sector.  Both irrigated and nonirrigated crop
production and water supply relationships are included for most
regions.  The model stimulates a long-run, perfectly competitive
equilibrium, and was developed using 1980-83 economic and
environmental parameters.

Limitations

     The economic approach used in this study has several
limitations.  The economic model is static in the sense that it
simulates an equilibrium response to climate change, rather than
a path of future changes.  Substitution of appropriate crop
varieties and adjustments in farm management techniques were not
included, thus possibly overestimating the negative effects of
climate change.  Estimates of the beneficial direct effects of
CO2 on crop yields may have biased  results in the  positive
direction.  Furthermore, changes in yields used as inputs to the
economic model were only modeled for wheat, corn,  and soybeans
for a limited number of sites and regions, and national estimates
were derived from these for all other crop commodities in the
model.  This introduces uncertainties into the results.

     Potential changes in international agricultural supply,
demand, and prices due to climate change are not explicitly
included in the model.  Such changes could have major impacts on
U.S. agriculture.

Results

     The economic model showed a small to moderate aggregate loss
in economic welfare associated with the projected crop yield and
hydrologic changes derived from the climate change scenarios (see
Table 10-3).  For the moderate climate change scenario, net
losses were small; for the more extreme scenario,  they were
greater.

     Production of most crops was reduced because of yield
declines and limited availability of land and resources.  The
largest reductions were in sorghum (-20%), corn (-13%), and rice
(-11%) , because these estimated losses are equivalent to 5 and
28% of the 1982 value of crop and livestock commodities produced
in the United States.  The magnitudes of these changes, which are
annual, may be compared to the estimated $6 billion cost of the
Drought Relief Bill for 1988.  In general, consumers lose and
producers gain due to the increased prices of agricultural

                              10-19

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                                                      Agriculture   ^
Table 10-3.    Aggregate Economic Effects of GISS and GFDL 2xC02
               Global Climate Change on U.S. Agriculture (in
               billions of 1982 dollars)
                                    Economic Effects
   Run                       Consumers   Producers   Total


GISS Analysis 4a                 -7.3       +1.5        -5.0

GFDL Analysis 4                -37.5       +3.9      -33.6



aAnalysis  4  includes  the  crop  yield  and  irrigation water supply
 and demand consequences of climate change throughout the United
 States.

Source: Adams et al., Volume _.
                              10-20

-------
Chapter 10

commodities and inelastic demand (insensitivity to price changes)
for agricultural crops.

     Agricultural activity would shift northward with both GISS
and GFDL climate change scenarios (see Figure 10-6).  Land under
production in Appalachia, the Southeast, the Mississippi Delta,
and the Southern Plains, could decrease by 5 to 25%, while in the
Lake States, the Northern Plains, and the Pacific it could
increase by 5 to 17%.  Irrigated acreage is estimated to increase
in all areas, primarily because irrigation becomes economically
feasible as agricultural prices rise (see Figure 10-7).  Demand
for additional water may be met in part by increased groundwater
pumping, although this could be a matter of concern in areas
where groundwater is already being overdrawn.  Since changes in
precipitation and recharge patterns are likely with climate
change, the availability of groundwater and the costs to extract
it might also be affected (see chapter on Water Resources).

     The impact of higher C02 levels  on crop productivity would
probably reduce the negative economic impacts of climate change
on the agricultural sector (Table 10-4).  Under the less severe
GISS climate scenario, the C02 direct effects would sufficiently
counter the climatic effects in most regions, so that the net
effect would be a gain in economic welfare.  Consumers would be
the primary beneficiaries, though (in aggregate) producers would
also gain slightly.  However, because the climatic effects on
crops differ by region, the output of some regions would
increase, while that of others would decrease.  With the more
severe GFDL climate change scenario combined with the direct
effects of C02,  economic welfare  still  would decrease,  but not  by
as much as it did with the climate change scenarios alone.  Here,
consumers would be the losers.

     Technological change, such as higher yielding crop
varieties, chemicals, fertilizers,  and mechanical power, has
historically enabled agriculture to increase production with the
same amount of or less land,  labor,  and other resources.  When
the effect of future technological change was modeled along with
the less severe GISS climate change effects (without the direct
effects of C02) , most of the  adverse  climate effects were offset.
Under the severe GFDL climate change scenario, continued and
substantial improvements in yields would be required to overcome
the climate change effects.   Stated another way, the adverse
effects of climate change would negate most of the higher output
attributable to improved technology over the next 50 years.
                              10-21

-------
                                            Q>
                                            tP
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                                0)
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10-23

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                                                      Agriculture   ^
Table 10-4.    Combined Effects of Direct CO2  and  Climate Change
               on Agriculture:  GISS and GFDL Analyses 4
                                 Economic Effects
                                     Producer
 Run                     Consumer  ($ billion)     Total


GISS Analysis 4:            -7.3        1.5         -5.9
 without C02

GISS Analysis 4:             9.4        1.3         10.6
 with C02

GFDL Analysis 4a:           -37.5       +3.9        -33.6
 without CO2

GFDL Analysis 4:           -10.3        0.6         -9.7
 with C02


Analysis 4  includes the crop  yield and  irrigation water supply
 and demand consequences of climate change throughout the United
 States.

Source:  Adams et al., Volume _.
                              10-24

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Chapter 10

Implications

     Food Supply

     Although climate change could reduce the productive capacity
of U.S. agriculture, the reduction does not imply major
disruption in the supply of basic commodities for American
consumers.  Domestically, consumers would face slightly to
moderately higher prices under some analyses, but supplies would
be adequate to meet current and projected domestic demand.
However, most exported commodities in some scenarios decline by
up to 70%, assuming the demand for exports remains constant.

     While climate change does not appear to be a food security
issue within the United States, supply and demand for
agricultural commodities could shift among international regions.
Responses of U.S. agriculture would take place in this global
context.  These changes in global agriculture cannot be
determined without analyzing the potential impacts of climate
change on both major world agricultural production regions and
potentially vulnerable food deficit regions.

     Regional Economics and Land Use

     Regional shifts in U.S. agricultural production patterns are
highly likely, as all analyses showed a consistent northward
shift in the production of the major commodities of wheat, corn,
and soybeans  (see Figure 10-6).  Other crops, including specialty
crops such as vegetables and fruits, could also shift.  Where
agricultural acreage declines, this might further weaken an
economic base already under pressure from long-term structural
changes in U.S. agriculture.

     Environmental Concerns

     Regional agricultural adjustments could place environmental
resources at risk.  Where agricultural acreage would increase,
demands for natural resources, such as soil and water, might
intensify current pressures on environmental elements, such as
rivers, lakes, aquifers, wetlands, and wildlife habitats.
Northern States, such as Minnesota and North Dakota, could become
more productive for annual crops like corn and soybeans because
of warmer temperatures and a longer frost-free growing season.
Because of the presence of forests and wetlands in these regions,
increased agricultural production in the area might threaten
natural ecosystems, including wildlife habitats such as prairie
potholes for ducks and flyways for bird migrations.
                              10-25

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                                                      Agriculture

     In addition, many of the glacial till soils in the northern
latitudes are not as productive as Corn Belt soils.  Thus, large
increases in production of crops would most likely require
increased applications of chemical fertilizers.  The use of these
fertilizers in humid regions on glacial till and sandy soils is
now creating an environmental hazard to the underlying
groundwater, receiving waters, and aquatic habitats in many
areas.  With climate change, water and fertilizer use would have
to be carefully managed to minimize still more leaching of water-
soluble nutrients such as nitrogen and potash, while continuing
to provide enough nutrients for crop growth.

Demand for Water for Irrigation

     Water is the single most critical factor in determining the
development, survival, and productivity of crops.  The amount of
water that crops use and thus the demand for irritation water are
governed largely by the evaporation process.  The projected
higher air temperatures due to increasing trace gases in the
atmosphere could heighten evaporative demands.  Farmers may
irrigate more to satisfy these higher demands, which could
accelerate depletion of groundwater and surface water resources.
Also, the rate of evaporation might outstrip precipitation, thus
decreasing crop yields.

     Studies reported in the California and the Great Plains case
studies (see Chapters 4 and 5) explicitly examined the potential
changes in demand for water for irrigation.  In these regions,
water is a critical resource for agriculture; California and the
parts of the Great Plains fed by the Ogallala Aquifer, in
particular, depend very heavily on irrigation for crop
production.

Irrigation Requirements in the Great Plains

     Allen and Gichuki (see Volume _) computed irrigation water
requirements for sites in the Great Plains for the baseline
climate and the GISS and GFDL climate change scenarios.  The
direct effects of CO2 and water use were  also included.   (See
Chapter 7, Great Plains,  for study design and limitations.) Major
changes in irrigation water requirements were observed at all
locations in the Great Plains, for all crops (see Figure 10-8).
The most significant were the persistent increases in seasonal
net irrigation water requirements for alfalfa, which were driven
by the climate changes in temperature, wind, humidity, and solar
radiation, and by the lengthening of the growing season.
Decreases in irrigation requirements were observed for winter
wheat and corn in most regions.  These decreases were attributed
to earlier planting dates and the shortening of the crop-growing

                              10-26

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I
i


I
               I

               i
               I
               i
               i
               i
               I
               I
                        120
                        100
                        ao
                        60
                        4O
                        20
         10
                        -10
                       -20
                                    ALFALFA
                             i    i   i    i    i    i   i    r
                                      CORN

                                     WHEAT
t
o
-2
-6
-6
-10
-12
-16
, 	 ,












-











-




1 	 1


















1 1 1 1 1 1 1 1
 Figure  10-8.  Percent change in net seasonal irrigation
              requirements with a 20% increase in bulk stomatal
              diffusion resistance.


'Source:  Allen and Gichuki, Volume 	.
                              10-27

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                                                      Agriculture

season by high temperatures.  When crop varieties appropriate to
the longer growing season were modeled, irrigation water
requirements for winter wheat increased.  Irrigation water
requirements during peak periods increased in almost all areas
(see Figure 10-9).

     While farmers in the Great Plains would probably shift to
longer season crops, the predicted climate conditions (warmer
temperatures and predicted drying in some areas) during the later
summer months could increase irrigation requirements and elevate
leaf temperatures to a point that exceeds optimum temperatures
required for high productivity.  This might make it uneconomical
to take full advantage of the predicted longer growing season,
especially if the higher C02 levels  increase  photosynthesis and
offset the effects of a shorter season to some degree.

Water Resources for Agriculture in California

     In the California regional case study, Dudek (see Volume _)
characterized the potential shifts in demand for water for
agricultural production that would accompany shifts in cropping
patterns driven by changing climate.  (See California chapter for
study design and limitations.)   When climate change was
considered alone, groundwater extraction and surface water use
declined in California as a result of changes in both supply and
demand.  When the direct effects of CO2 on crop  yields were
included, however, groundwater extraction increased due to
improved yields of all crops except corn and to enhanced economic
welfare.  Institutional responses to changes in surface and
groundwater use include water transfers, which improve irrigation
efficiency.  When water markets were included in the simulations,
economic welfare was improved by 6-15% over the base, while crop
acreage increased and groundwater extraction decreased.

Implications for Demand for Water for Irrigation

     Expanded use of irrigation is implied from the regional crop
modeling studies for the Great Lakes, the Southeast, and the
Great Plains (see Chapters 5, 6, and 7).  Increases in irrigated
acreage are also predicted for most regions when the economics of
crop production are factored in (see Adams et al., Volume _).
When these results are considered along with the other Great
Plains and California studies,  it appears that climate change is
likely to increase the demand for irrigation.

     In the Great Plains, heightened evaporative demand and
variability of rainfall may increase the need for irrigation in
dryland farming regions.  The projected changes in irrigation
water requirements are varied,  and specific crops and locations

                              10-28

-------
                              Corn
        so


        70


        6O


        50


        4O


        30


        20


        10


         0


        -10
             NE-OSS      KS-GSS      OX-OSS      TX-OSS
                            KS-CRX     OK-GFDL      TX-GRX
Figure 10-9.
Percent change  in peak irrigation requirements  of
corn with a 20%  increase in bulk stomatal

diffusion resistance.
Source:  Allen  and  Gichuki,  Volume _.


                               10-29

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                                                      Agriculture

probably will be affected differently.  Higher peak irrigation
water requirements for some crops may require larger capacity
irrigation systems and enlarge energy demands.

     Intensified extraction of water poses serious environmental
and economic problems, especially in areas where groundwater is
being overdrawn.  Streamflows also may slacken if more surface
water is used for irrigation, thereby aggravating water quality
problems.  This in turn would harm fish, wildlife, and
recreational activities.

     Regional changes in cropping locations and patterns of water
use also could exacerbate agricultural, nonpoint source pollution
and further deplete groundwater resources.  Institutional
responses, such as markets for water transfers, could help
improve irrigation water management and alleviate some of these
negative effects.

     The economic and social costs of shifting the location of
irrigated agriculture could be considerable.  The construction of
irrigation systems consisting of reservoirs, wells, ditches,
pipes, pumps, and sprinklers currently requires about $1,500-
5,000 per hectare (ha) in capital investment  (Postel, 1986).

Direct Effects of CO2 on Crops

     Global increases in C02 are expected to influence crop
metabolism, growth,  and development directly through
physiological processes and indirectly through climate.  Rose
(see Volume _) reviewed recent experimental work performed on the
direct effects of CO2 on crops,  with emphasis on wheat,  corn, •
soybeans, and cotton.

     Elevated concentrations of CO2  directly affect plant
processes such as photosynthesis and transpiration.  CO2
concentrations are also expected to influence these processes
indirectly through predicted increases in temperature and other
changes in climate variables such as precipitation.  Because
experimental research has rarely simultaneously studied both the
direct and indirect effects of plant responses, it is difficult
to assess the relative contributions of elevated C02 and climate
changes to predictions of crop responses.

     Research on the physiological effects has focused primarily
on responses of rates of photosynthesis and transpiration to
increasing concentrations of atmospheric C02.   Photosynthesis
rates have increased in these crops in relatively ideal
experimental environments.  At moderate temperatures, most crops
will probably show increases in size and possibly yield as C02

                              10-30

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Chapter 10

concentrations rise.  However, plants also have internal
regulation mechanisms that may lessen these effects under field
conditions.

     Transpiration rates per unit leaf area decrease, while total
transpiration from the entire plant sometimes increases because
of greater leaf area.  Drought-stressed plants exposed to high
partial pressures of C02 should be better able to  cope with water
deficits.  Leaf temperatures in all species are expected to rise
even more than air temperatures, which may inhibit plant
processes that are sensitive to high temperature.

     Few studies have examined the interactive effects of C02,
water, nutrients, light, temperature, pollutants,  and sensitivity
to daylength on photosynthesis and transpiration.   Even fewer
studies have examined the effects of these interactions on the
growth and development of the whole plant.  Therefore,
considerable uncertainty exists concerning the extent to which
the beneficial effects of increasing C02 will  be seen in crops
growing in the field under normal farming conditions with climate
change.

Climate Impacts on Pest-Plant Interactions

     Compared to the existing information on the potential
effects of climate change on crop production,  relatively little
effort has been directed toward assessing the influence of
climate change on plant-pest interactions.  Atmospheric increases
in temperature and C02,  and changes in moisture regimes,  all can
directly or indirectly affect interactions between pests and
crops.

Study Design and Results

     Stinner et al. (see Volume _) conducted a literature survey
and modeling experiments on the major mechanisms through which
climate change may affect pest-plant interactions.  This study
emphasized the major insect pest and pathogen species of corn and
soybeans.  The survey indicated that temperature and
precipitation patterns are the key variables that affect crop-
pest interactions.  The temperature increases associated with the
climate change scenarios bring about the following trends:  (1)
increased survival for migratory and nonmigratory insect pest
species in the winter, (2)  northern range extensions of current
pests in the higher latitudes and migration of southern species
into the northern Grain Belt regions, (3) an increase in pest
species with more than one generation per year in the northern
                              10-31

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                                                      Agriculture

Grain Belt, (4) earlier establishment of pest populations in the
growing season, and (5) increased abundance of pests during more
susceptible growth stages of crops.

     The potential changes in the overwintering ranges of four
major pests were mapped for the GISS and GFDL climate change
scenarios and were compared to present ranges.  The overwintering
capability of the four major pests may extend northward with both
climate change scenarios.  For example, the potato leafhopper, a
serious pest on soybeans and other crops, at present overwinters
only in a narrow band along the coast of the Gulf of Mexico
(Figure 10-10).  Warmer winter temperatures predicted by both the
GFDL and GISS models suggest a doubling or tripling of the
overwintering range in the United States, respectively.
Increases in the winter population density of this size would
increase the invasion populations in the northern States by
similar factors.  The invasions also would be earlier in the
growing season, assuming.planting dates dp not change.  Both
features are likely to lead to greater insect density and damage.
This pattern is repeated with the other three pests studied and
indicates that these pests, and possibly others, may move
northward and invade cropping systems earlier in the growing
season under climate change conditions.

     The Soybean Integrated Crop Management (SICM) model (Jones
et al., 1986)  was run with the GISS and GFDL climate change
scenarios to estimate changes in damages caused by corn earworm.
Modeling results show that earworm damage to soybeans will
increase in severity in the Grain Belt under a warmer climate.
Such damage could cause grain farmers in the Midwest to suffer
significant economic losses.  These results were particularly
marked with the warmer and dryer GFDL scenario.

Study Limitations

     Lack of knowledge about the physiological effects of CC>2 on
crop plants and lack of experimental evidence on direct effects
of CO2  on insect-plant  interactions make  the study of pest-plant
interactions particularly difficult.  Only one cultivar is used
in the modeling study under both the baseline and the climate
change scenarios.  In reality, farmers would probably switch to a
more climatically adapted cultivar as climate changed.

Study Implications

     Increased pest-related crop damage could intensify pesticide
use.  The economic and environmental ramifications of such an
increase could be substantial, not only in current farming
regions but also in new areas as agriculture shifts to the more

                              10-32

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                                                      Agriculture

northern regions such as the Northern Plains, the Great Lakes
States, and the Pacific Northwest (see Figure 10-6).

     Increased use of pesticides would create additional threats
to the integrity of ecosystems through soil and water
contamination and could increase risks to public health.  If
agricultural production is not to rely increasingly on chemicals
that are potentially harmful to the environment, an increased
need will exist for alternative pest management strategies such
as biological control, genetic resistance, and innovative
cropping systems.

Effects of Climate Change on Water Quality

     Agricultural pesticides are ranked as a high priority
pollution problem in many rural regions.  Potentially toxic
agricultural chemicals can be transported away from fields via
runoff of surface soils and via downward leaching and percolation
through the soil.  An understanding of these processes is
essential to the evaluation of potential threats to drinking
water quality caused by climate change.

Study Design

     Johnson et al. (see Volume _) modeled the partitioning of
agricultural pesticides among uptake, degradation, surface
runoff, and soil leaching for wheat, corn, and cotton production
regions in the Great Plains and the Corn Belt.  (See the Great
Plains chapter of this report for details of the study.)  They
used the Pesticide Root Zone Model  (PRZM) (Carsel et al., 1984),
which simulates the vertical•movement of pesticides in the soil.
The model consists of hydrological and chemical transport
components that simulate runoff, erosion, plant uptake, leaching,
decay, foliar washoff, and volatilization of a pesticide.  The
interactions among soil, tillage, management systems, pesticide
transport, and climate change were studied.

Limitations

     The frequency and duration of precipitation remain the same
in the climate change scenarios, even though these storm
characteristics are critical factors in determining the transport
of agricultural chemicals and may change.  The scenarios assume
that the number of days with rainfall does not change, but the
intensity of rainfall increases or decreases.  Runoff and
leaching estimates would most likely be different if the number
of days of rainfall changed and daily rainfall amounts were held
constant.
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Chapter 10

     The PRZM is a one-dimensional, point model that does not
simulate the transport of water below the root zone.  Thus,
results on a regional basis must be extrapolated with care.  The
direct effects of COj on crop growth,  which may increase the size
of the plants and the extent to which crops cover the soil, are
not included.

Results

     Regional changes in chemical loadings of water and sediment
are likely but probably will not be uniform.  There appears to be
some consensus between the GCM scenarios concerning the estimated
regional changes (Table 10-5).  Modeled pesticides in runoff
increase in the cotton production area, and pesticides carried by
sediments decrease in the spring wheat and corn regions.
Leaching of pesticides tends to be less everywhere owing to
changes in seasonal precipitation and increased evaporation.

Implications

     When the changes in water quality from the predicted climate
change scenarios are considered in conjunction with the predicted
increases in pests and implied higher applications of pesticides
described in the study on pest-plant interactions, the potential
for changes in the nation's water quality becomes apparent.  Any
deterioration in water quality could adversely affect public
drinking water supplies and human health.

Climate Variability

     The impacts of climate change result not only from a slow
change in the mean of a climate variable but often from shifts in
the frequency of extreme events.  Droughts, freezes, and
prolonged periods of hot weather have strong effects on
agricultural production.  While the agricultural modeling studies
did not include the effects of potential changes in climate
variability, Mearns and Schneider (see chapter on Climate
Variability in this report) reviewed literature on agriculture
and extreme events to determine the nature and magnitudes of
significant impacts.

     Corn,  soybeans, wheat, and sorghum are sensitive to high
maximum temperatures during blooming.   Lower yields of corn,
wheat,  and soybeans have been found to be correlated with high
temperatures.  The damaging effect of runs of hot days on corn
yields was particularly evident in 1983 in the U.S. Corn Belt.

     Although low temperatures may be less of a problem with the
predicted climate change,  risks of frost damage to crops may

                              10-35

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Table 10-5.
                                                          Agriculture
Summary of GCM Model Consensus of PRZM Pesticide Transport
by Cropping Region and Pesticide3
                               Surface
                              Pesticides
                             Runoff Losses
                                  Surface
                                 Pesticide
                               Erosion Losses
Pesticide
Leaching
SPRING WHEAT:

Highly soluble/short-lived6
Highly soluble/long-lived
Slightly soluble/long-lived

WINTER WHEAT:

Highly soluble/short-lived
Highly soluble/long-lived
Slightly soluble/long-lived

COTTON:

Highly soluble/short-lived
Highly soluble/long-lived
Slightly soluble/long-lived

CORN:

Highly soluble/short-lived
Highly soluble/long-lived
Slightly soluble/long-lived
                                    +
                                    -t-
a  +  indicates that median values  increase  under  climate change;  -
indicates that median values decrease under climate change; blank
indicates no consensus among median values.

b  ex.  median value of all tillage,  soil, weather site  scenarios  for
highly soluble/short-lived pesticides in the spring wheat crop area,

Source:  Johnson et al., Volume _.
                                  10-36

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    Chapter 10
change in the growing areas of certain crops.  Citrus trees are very
vulnerable to low minimum temperatures.  Winter wheat is often damaged by
low temperatures known as winter kill, especially in the absence of snow.
(See Glantz, Volume _, for a discussion of how the Florida citrus
industry adapted to increased frequency of freezes in the 1980s.)  Even
with warmer winters and fewer frosts, more damage can occur at less
extreme temperatures.  For example, the effect of freezing temperatures
is exacerbated if the crops have not yet been hardened by the cold, or if
they are no longer dormant and a cold snap occurs.

    Drought is a major cause of yearly variability in crop production.
In the Dust Bowl years of the 1930s, yields of wheat and corn in the
Great Plains dropped to as much as 50% below normal.  In 1988,
agricultural disaster in areas of the northern Great Plains demonstrated
a high vulnerability to drought; and nationwide a nearly 40% decrease in
U.S. corn yields is predicted.  Reduction in vegetative cover associated
with drought also brings about severe wind erosion of soils, which will
affect future crop productivity.  Low yields of forage crops during
droughts result in food shortages for livestock and premature selling of
livestock.

Farm-Level Management and Adjustments to Climate Change

    Adjustments to existing production practices are the first course of
action in the face of climate change.  The net effect of climate change
with adjustment by farmers may be significantly different from the
estimated effects of climate change alone.

Study Design

    Several studies addressed possible adjustments that could modify the
effects of climate change.  These adjustments include changes in planting
and harvesting dates, tillage practices, crop varieties, application of
agricultural chemicals, irrigation technology, and institutional
responses for management of water resources.

Results of Adjustment Studies

    Ritchie et al. demonstrated that the yield reduction in corn in the
Great Lakes can be partly overcome with selection of new cultivars that
have a longer growing season (see Great Lakes chapter of this report).
Rosenzweig (see Great Plains chapter of this report) showed that
adjusting the planting date of winter wheat to later in the fall did not
ameliorate the effects of climate change,  but that changing to varieties
more suited to the predicted climate overcame yield decreases at some
locations.


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                                                      Agriculture

     Dudek's California study found that flexible institutional
responses to climate change helped to compensate partly for
negative climate change effects (see California chapter of this
report).  By allowing movement of water around the State by
transferring water rights, California water resource managers can
alleviate some groundwater extraction and compensate for surface
water reductions.

     Easterling  (see Great Lakes chapter of this report) found
that potential farmer adjustments to climate change include
changes in tillage practices, increased fertilizer application,
more full-season and heat-resistant varieties, changes in
planting densities, higher pesticide use, earlier harvest, and
less artificial drying.  Different adjustments would occur at
different times in the cropping season.  With the hotter and
drier GFDL scenario, farmers may be forced to adopt production
practices that are different from those in use today.  Climate
changes that leave soils drier during summer than they are at
present will most likely lead to increased use of irrigation in
the Corn Belt.  This increased use of irrigation is also
supported by the projected price increases for all crops grown in
Illinois.

Implications of Adjustment Studies

     Although detrimental climate change effects on agriculture
may be partly offset naturally by increased photosynthesis and
water-use efficiency caused by higher levels of atmospheric
carbon dioxide, farmers will no doubt use a variety of
adjustments to adapt to climate change.  Market forces also will
aid adaptation to climate change because they help to allocate
resources efficiently.      ,

     More severe climate changes are likely to necessitate major
adaptations, such as farm abandonment in some regions.  Prior
investments may be lost as existing infrastructures become
obsolete and new investments are needed for new locations.  Some
of these adjustments could be costly.

     Improvements in agricultural technology also may be expected
to ease adjustment by development of appropriate farming
practices and crop variety and livestock species.  Adjustment and
adaptation to climate change should be included in agricultural
research programs to enable this process to occur.

Livestock

     Animal products are a critical source of protein, energy,
vitamins, and minerals.  U.S. livestock production, mainly from

                              10-38

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Chapter 10

cattle, swine, sheep, and poultry, was estimated to be worth over
$31 billion in 1986  (USDA, 1987).

     Climate is known to significantly affect many aspects of
animal health and production.  The direct effects of climate
change on animal health include differences in incidence of heat
and cold stress, changes in weight gain, and decline in
reproductive capabilities.  Indirect effects may involve trends
in agricultural commodities, such as the availability and prices
of types of animal feeds and the expanded geographic distribution
and activity of disease-carrying vectors.

     Higher winter temperatures may lower the incidence of
respiratory diseases in livestock (Webster, 1981).  Conversely,
warmer summers may necessitate more hours of indoor cooling
during which pathogens are confined to housing structures.
Climate warming may significantly increase the costs of air-
conditioning in poultry housing.  Changes in reproductive
capabilities such as decreased ovulation rates, shortened
intensity and duration of estrus, decreased fertility of males,
and increased embryonic mortality also have been shown to occur
with high temperatures (Ames, 1981).

     Climate change may also affect the survivability, activity,
and geographic distribution of vectors responsible for the
transmission of infectious diseases in livestock.  The activity
and reproduction of disease-carrying vectors infecting livestock,
humans, and crops are driven primarily by temperature, humidity,
and precipitation.  These impacts are likely to be similar to
those on mortality and morbidity of disease in humans (see
chapter on Human Health,  this volume), and they also are similar
to changes predicted for crop pests.

Design of Livestock Studies

     Stem et al. (see Volume _)  studied the available literature
on four diseases to evaluate the range of potential changes in
disease distribution and occurrence under climate change
conditions.  Schmidtmann and Miller (see Volume _) used a
population dynamics simulation model to estimate the effects of
the GFDL climate change scenario on the life cycles of the horn
fly, a ubiquitous pest of pastured cattle throughout the United
States.

Results of Livestock Studies

     Stem et al. found that, under warmer conditions, livestock
diseases currently causing serious economic losses in tropical
countries could spread into the United States.   Rift Valley fever

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                                                      Agriculture

is transmitted principally by mosquitoes,  and danger of the
disease may spread as rising winter temperatures become able to
support an active increase in the mosquito population.  African
swine fever also may become more of a threat.

     The ranges and activities of disease-carrying agents of blue
tongue and anaplasmosis, diseases currently causing severe losses
in cattle and sheep in the United States,  may expand.  If
disease-carrying insects increase their winter survival and
reproduce year-round in more States, the geographical
distribution of blue tongue, which is caused by a virus, may
expand northward and eastward.  Anaplasmosis, a rickettsial
infection of ruminants, is the second most important disease of
cattle in the United States.  The distribution of the habitat of
the insect carrier of the disease could expand to northern States
with climate change, and the day-to-day activity of the insects
may increase, also causing an increase in disease transmission.

     The horn fly causes annual losses of $730.3 million in the
beef and dairy cattle industries (Drummond, 1987).  Schmidtmann
and Miller found that with the very warm GFDL climate change
scenario, the horn fly season throughout most of the United
States was extended by 8 to 10 weeks, horn fly populations
increased (see Figure 10-11),  and the average daily gain in beef
cattle decreased.  This horn fly increase will cause
substantially greater reductions in the average daily gain of
growing beef cattle.  The GFDL simulation also increased pest
activity in dairy cattle in the northern and northwestern States,
a result that could significantly decrease milk production.
Conversely,  the summertime activity of the horn fly decreased in
the southern States because the warmer climate exceeded the horn
fly's tolerance to high temperatures.

Limitations

     Horn fly data are based on counts taken at various times,
under varying weather and management conditions.  However, the
prediction of current horn fly populations appears to be well
correlated with observations.   The model is not validated for the
high temperatures predicted for the climate change.  Schmidtmann
and Miller used only the hottest scenario, GFDL; the other
scenarios may have resulted in less of a geographic shift in the
range of the horn fly.

     It should be noted that this analysis is based on current
livestock management breeds and distribution.  Possible changes
in these factors are beyond the scope of this study.
                              10-40

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Figure 10-11.
Current (C) and projected (P) populations of the
horn fly,  a major pest of beef and dairy cattle,
using the GFDL climate change scenario.
Source:  Schmidtmann and Miller, Volume _.
                              10-41

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                                                      Agriculture

Implications of Livestock Studies

     With climate change, patterns of livestock diseases and
pests may change.  Tropical livestock diseases may become more of
a threat, because more geographical areas are potential ranges
for the insect carriers of the diseases.  Temperature conditions
may improve in the winter but may be exacerbated in the summer.
Reproductive capabilities may be lower.


ECONOMIC AND ECOLOGICAL IMPLICATIONS

     Even though the U.S. agricultural system has historically
shown considerable resiliency and may be less vulnerable to
climate change than unmanaged ecosystems, many reasons to avoid
complacency concerning the predicted climate change remain.
While the studies summarized in this chapter show that the U.S.
supply of basic commodities probably is not threatened by climate
change, food prices may increase for consumers, and agricultural
exports may be significantly reduced.

Costs of Adjustments

     Since our agricultural production system consists mostly of
specialized farms producing commodities in geographically
specialized patterns of production, the costs of adjustments to
changes in comparative advantage among agricultural regions with
ensuing changes in resource use and agricultural infrastructure
may be quite high.  These shifts will also entail involvement of
and costs to the Federal Government.

Effects of CO2

     It is also important to note that the crop modeling studies
showed that the direct effects of CO2 on crop photosynthesis and
water-use efficiency ameliorate the negative effects of climate
change in some locations but not uniformly and not everywhere.
While much work remains to be done to improve both climate and
crop models, reliance on overly optimistic assessments about the
beneficial effects of C02 must  be avoided when policy options are
considered.

Water Quality

     Changes in the agricultural production system are likely to
have significant impacts on resource use and the environment.
Many of the agricultural studies suggest that climate warming
could result in changes in water quality from agricultural
chemicals, increases in pesticide usage to control changes in

                              10-42

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Chapter 10

pest vectors, and accelerated rates of demand for water for
irrigation.  Climate change could thus exacerbate many of the
current trends in environmental pollution and resource use
associated with agriculture as well as initiate new ones.

      A northward migration of agriculture will increase the use
of irrigation and fertilizers on sandy soils, thus endangering
underlying groundwater quality.  From South Dakota to southern
Canada, critical prairie wetlands may be lost to drainage and
conversion to cropland.  Many of these areas are important
wildlife habitats.  Shifts in agricultural activities may
increase the susceptibility of soils to wind and water erosion.

Global Agriculture

     Finally, U.S. agriculture is an integral part of the global,
international agricultural system.  Consequently, the adjustment
of U.S. agriculture to climate change cannot be considered in
isolation from the rest of the world.  The optimal configuration
of U.S. adjustments will depend very much on how simultaneous
changes in regional climate affect global agriculture and how
other countries, in turn, respond to those changes.
NATIONAL POLICY IMPLICATIONS

     Since climate change appears likely to reconfigure the
agricultural activities and demographics of rural America,
policies are needed to ease the inevitable adjustments and ensure
the sustainability of our natural and human resources (see Schuh
and Dudek, Volume _).   Following are specific policy areas that
policymakers could investigate to respond appropriately to the
projected climate change.

commodity Policies

     Agricultural pricing and production policies should promote
efficient adjustment to the changing conditions of global supply
and demand induced by the greenhouse effect, which may include
shifts in comparative advantage among regions and increased
likelihood of droughts in some regions.  Although these shifts
may be slow, the cumulative effects are large and they deserve
close monitoring.  Market forces as well as government programs
will play a crucial role in creating the flexibility to respond
to climate changes by sending signals on the efficient use of
resources, and in mitigating their ultimate impact as they have
done in the past.  Agricultural policies should be evaluated to
ensure that they are appropriate to both current and future
conditions.

                              10-43

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                                                      Agriculture    •

Land-Use Programs

     Federal legislation aimed at reducing the use of newly
plowed grasslands, e.g., the "Sod-Buster Bill," and the related
"Swamp-Buster Bill," which restricts agricultural encroachment
into wetlands subject to flooding and water-logging, are examples
of new policies meant to protect marginal lands.  The basic goals
of these new laws, which are part of the 1985 Farm Bill, are to
protect the most erodible farmland by removing it from crop
production and to use conservation as a tool for reducing
overproduction.

     Another program established in the 1985 Farm Bill, that may
help alleviate the negative effects of climate change is the
Conservation Reserve Program.  This program is aimed at removing
from crop production the cropland classified as "highly erodible"
by the Soil Conservation Service.  The bill created a new form of
long-term contract of up to 10 years and provides payments to
farmers who apply conservation practices, such as maintaining a
grass cover, on those acres.  If successful, the Conservation
Reserve Program may reduce the impact of climate fluctuations on
total grain production by taking the most sensitive lands out of
use.                                                        ..        ^k

     The 1988 drought, however, demonstrates that the
Conservation Reserve Program may be difficult to maintain in the
face of climate stress.  As the drought worsened during the
summer, use of the set-aside lands was requested so that badly
hit farmers could salvage some economic benefits from these
acres.  Such conflicts may be more common in the future, and land
retirement strategies must be weighed against possible needed
increases in production in the future.

     Awareness of potential changes in agricultural land use due
to regional climate change should be built into land-use planning
programs, especially in regions where agricultural activities may
expand into natural, unmanaged ecosystems.  Large-scale drainage
and water projects would need environmental impact studies to
carefully assess this potential expansion of agricultural land
(see Baldwin, Volume _).

Water-Resource Management Programs

     Current water supply policies do not generally encourage
optimum water-use efficiency.  A greater degree of water
efficiency should promote flexibility in light of the potential
for increased irrigation demands with climate change.  Policies
such as water transfers and markets should be evaluated for          4|
irrigated areas.                                                     ™

                              10-44

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Chapter 10


Water Quality Policy

     The increased use of agricultural chemicals, and changes in
the hydrological cycle, threaten both soil and water supplies,
and eventually, public health.  These effects could be
ameliorated by including potential climate change effects in
water quality planning and by supporting alternative pest
management strategies that use such techniques as biological
control, genetic resistance, and innovative cropping systems.

Risk Management

     Changes in the frequency, intensity, and location of extreme
events are important for agriculture and the regional income that
it produces.  The adequacy of the private crop insurance and
Federal disaster payment programs should be assessed in the face
of climatic uncertainty.  For example, only about 20-25% of
potentially insurable acreage is currently covered by crop
insurance.  Farmers tend to rely on Federal disaster relief
programs to bail them out of such disasters as droughts, floods,
hail, and windstorms.  Financial risk is also part of the credit
structure that covers land, equipment, and production in modern
farming.

     The frequency and magnitude of climate extremes may be
altered with climate change.  Responding to the changes may be
costly for the government if crops fail frequently.  The Drought
Relief Bill for the drought of 1988 is scheduled to cost $3.9
billion to cover just 1 year of a climatic extreme.  On the other
hand, some areas that currently suffer from climate extremes may
benefit from climate change.  Risk policy mechanisms for relief,
recovery, and mitigation of climate change should be examined so
that they will be ready to help farmers adjust.

International Trade Agreements

     Policies designed to ease the adjustment to greenhouse
effects must be global in scope because the effects, although
varied, are global in nature.  Comparative advantage will shift
significantly both within the United States and in other
countries.  Population and economic activities also will change
geographically with climate change, thus affecting the location
of demand for agricultural products.  It is already a goal of
U.S. agricultural policy to incorporate global conditions of
supply and demand into the agricultural sector.  The potential
seriousness of the impacts on the agricultural production system
of the greenhouse effect may provide added incentive to establish
such policies both nationally and globally.  The vulnerability of

                              10-45

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                                                      Agriculture

current and potential food-deficit regions to climate change
should also be considered.

Agricultural Contributions to the Greenhouse Effect

     Agriculture itself is an active contributor to the
greenhouse effect.  Clearing of forested land for agriculture
often involves burning of trees and shrubs that release CO2.   The
biomass that is not burned tends to decay gradually, also
emitting CC>2.   Agricultural  activities  release other radiatively
active trace gases.  Flooded rice fields emit methane (CH4)  as a
product of the anaerobic decomposition of organic matter.
Ruminants also release methane as. a consequence of their
digestive processes.  In addition, soils may volatilize some of
the nitrogenous fertilizer applied to them in the form of nitrous
oxide (N20) .   Finding effective ways  to reduce these emissions
presents a major challenge to the agricultural research
community.  In this regard,  the Conservation Reserve Program and
forestation efforts could provide a partial solution, since
vegetation fixes CO2 from  the air.

Agricultural Research

     The agricultural research community should enhance climate
change research from the field level to the national policy
level.  It should continue to breed heat- and drought-resistant
crop varieties and new crop species in preparation for global
warming.  Research in biotechnology may also be directed toward
alleviating the negative effects of climate change.  Improved
water use and irrigation efficiency also take on renewed
importance in the light of potential climate change.

     Reduction of agricultural emissions of trace gases also
deserves research attention.  Development of nitrogen-fixing corn
would help decrease fertilizer applications and thus agricultural
emissions of N2O.   This  would also mean a significant improvement
in groundwater contamination.
RECOMMENDATIONS FOR FURTHER RESEARCH

     1.   Crop productivity — Study the interactive effects of
          climate variability and change, C02,  tropospheric
          ozone, UV-B from stratospheric ozone depletion, and
          other environmental and societal variables on
          agricultural productivity.

          Because of the significant changes in production
          indicated by these studies, the need for better

                              10-46

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Chapter 10
          simulation of the direct effects of C02  in  the  crop
          models,  and the limited adjustment studies performed,
          further research should be conducted on a longer term
          basis.  Necessary work includes validation of the crop
          models,  resolving the differences in forecasts of the
          GCMs, and designing more appropriate scenarios
          including changes in climatic variability.
          Physiologically based submodels are needed for the
          effects of increased CO2 on various  crops.  The effects
          on cotton also should be studied because cotton is a
          major crop, and because daylength may not allow it to
          shift northward.  All the crop models should be
          improved in their simulation of the effects of
          increasing temperatures.

          Research to this point has provided windows of
          knowledge concerning certain crops (especially
          soybeans) at specific stages of their life cycles.
          Both the direct and the climate change effects of high
          CO2  are  probably quite  different  at  different stages  of
          development.  Research should be performed on the
          interactive effects of C02 and  temperature  over the
          whole life cycle of the plant,  with realistic
          conditions of water and nutrition, rather than with
          "pampered" plants under optimal conditions.  Then crop
          response to the combined climatic and physiological
          effects of C02  may  be predicted more  realistically.

     2.    Adaptation strategies — The dynamic nature of climate
          change also needs to be studied:  What is the rate of
          adaptation of regional agricultural systems compared to
          the rate of climate change?   Evaluation of the
          thresholds of sensitivity of U.S. agriculture is
          needed.   Studies should analyze the ability of various
          aspects  of the agricultural  production systems to adapt
          to various rates and degrees of climate change to
          determine these thresholds of sensitivity.

     3.    Agricultural economics — Expand the national analysis
          to include crops and regions not now included (for
          example, cotton and grasslands, and pasture in the
          western  regions of the United States).   Conduct further
          analyses of regional implications of shifts in
          agriculture.

     4.    International agriculture — Study the potential shifts
          in international comparative advantage and  the
          vulnerability of food-deficit regions,  and  evaluate the
          implications of such shifts  for the United  States.

                              10-47

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                                                 Agriculture


5.   Environmental impacts — Elucidate the impacts of
     climate change on water quantity,  water quality,  and
     other components of the environment caused by shifts in
     crop and livestock production and  related industries.
                         10-48

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                                                          Agriculture

  FERENCES

Acock, B., and L.H. Allen Jr.  1985.  Crop respones to elevated carbon
dioxide concentrations. In: Strain, B.R., and J.D. Cure, eds. Direct
Effects of Increasing Carbon Dioxide on Vegetation. Washington, DC: U.S.
Department of Energy.  DOE/ER-0238.  pp. 33-97.

Adams, R.M.,  S.A. Hamilton, and B.A. McCarl.  1984.  The Economic Effects
of Ozone on Agriculture. Corvallis, OR: U.S. Environmental Protection
Agency.  EPA-600/3-84-090.

Ames, David R.  1981.  Effect of climate on livestock production data.
In: Knapp, F.W., ed. Systems Approach to Animal Health and Production.
Lexington, KY:  University of Kentucky, pp. 148-148.

Callaway, J.M., F.J. Cronin, J.W. Currie, and J. Tawil.  1982.  An
analysis of methods and models for assessing the direct and  indirect
impacts of C02-induced environmental changes in the agricultural sector
of the U.S. economy.  Richland, WA: Pacific Northwest Laboratory,
Battelle Memorial Institute.  PNL-4384.

Carbon Dioxide Assessment Committee.  1983.  Changing Climate.
Washington, DC: National Academy of Sciences.

 arsel, R.F., C.N. Smith, L.A. Mulkey, J.D. Dean, and P. Jowise.  1984.
 sers Manual for the Pesticide Root Zone Model  (PRZM). Athens, GA: U.S.
Environmental Protection Agency.  EPA-600/3-84-109.

Council for Agricultural Science and Technology.  1984.  Long-Term
Viability of U.S. Agriculture. Aces, Iowa.  Report No. 114.

Cure, J.D.  1985.  Carbon dioxide doubling responses: a crop survey.  In:
Strain, B.R., and J.D. Cure, eds. Direct Effects of Increasing Carbon
Dioxide on Vegetation.  Washington, DC: U.S. Department of Energy..
DOE/ER-0238.   pp. 99-116.

Decker, W.L., V. Jones, and R. Achutuni.  1985.  The impact of C02-
induced climate change on U.S. agriculture. In: White, M.R., ed.
Characterization of Information Requirements for Studies of CO2 Effects:
Water Resources, Agriculture, Fisheries, Forests and Human Health.
Washington, DC: U.S. Department of Energy. DOE/ER-0236.  pp. 69-93.

Doorenbos, J., and A.H. Kassam.  1979.  Yield Response to Water.  Rome:
Food and Agriculture Organization of the United States.  FAO Irrigation
and Drainage Paper 33.
                                  10-49

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                                                          Agriculture

Drummond, R.O.  1987.  Economic aspects of ectoparasites of cattle in
North America.  In: Leaning, W.H.D., and J. Guerrero, eds. Proceedings of
the MSD AGVET Symposium, The Economic Impact of Parasitism in Cattle.
XXIII.  World Veterinary Congress.  Montreal, Quebec,  pp. 9-24.

Hansen, J., I. Fung, A. Lacis, D. Rind, G. Russell, S. Lebedeff, R.
Ruedy, and P. Stone.  1988.  Global climate changes as forecast by the
GISS 3-D model.  Journal of Geophysical Research (In press.)

Horner, G., L. Putler, and S.E. Garifo.  1985.  The Role of Irrigated
Agriculture in a Changing Export Market.  Washington, DC:  U.S.
Department of Agriculture, Economic Research Service.  ERS Staff Report
AGES850328.

Jones, J.W., K.J. Boote, S.S. Jagtap, G. Hoogenboom, and G.G. Wilkerson.
1988.  SOYGRO V5.41: Soybean Crop Growth Simulation Model.  User's Guide.
Florida Agr. Exp. Sta. Journal No. 8304, IFAS.  Gainesville:  University
of Florida.

Jones, J.W., J.W. Mishoe, G.Wilkerson, J.L. Stimac, and W.G.  Boggess.
1986.  Integration of soybean crop and pest models. In: Frisbie, P.E.,
and P. Adisson, eds.  Integrated Pest Management on Major Agriculture
Systems.  Texas Agriculture Experiment Station.  Publication No. MP-1616.

Kimball, B.A.  1985.  Adaptation of vegetation and management practices
to a higher carbon dioxide world.  In: Strain, B.R., and J.D. Cure, eds
Direct Effects of Increasing Carbon Dioxide on Vegetation.  Washington,
DC: U.S. Department of Energy.  DOE/ER-0238.  pp. 185-204.

Land Evaluation Group.  1987.  Implications of climatic warming for
Canada's comparative position in agricultural production and trade.
University School of Rural Planning and Development.  University of
Guelph. Guelph, Ontario.

Monteith, J.L.  1965.  Radiation and crops.  Experimental Agricultural
Review 1(4):241-251.

New York Times.  August 12, 1988.  Drought cutting U.S. grain crop 31%
this year, by K. Schneider,  p. Al.

Parry, M.L., T.R. Carter, N.T. Konijn, eds.  1988.  The Impact of
Climatic Variations on Agriculture.  Vol. 1.  Assessments in Cool
Temperate and Cold Regions.  Kluwer, Dordrecht.

Postel, S.  1986.  Altering the Earth's Chemistry: Assessing the Risks.
WorldWatch Paper 71.  Washington, DC: WorldWatch Institute.
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    Chapter 10

 itchie, J.T., and S. Otter.  1985.  Description and performance of
CERES-Wheat: A user-oriented wheat yield model.  In: Willis, W.O., ed.
ARS Wheat Yield Project.  Washington, DC: U.S. Department of Agriculture,
Agricultural Research Service.  ARS-38.  pp. 159-175.

USDA.  1987.  U.S. Department of Agriculture.  Agricultural Statistics.
Washington, DC: U.S. Government Printing Office.

Warrick, R.A., R.M. Gifford, M.L. Parry.  1986.  CO2,  climatic change and
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Jager, and R.A. Warrick, eds.  The Greenhouse Effect, Climatic Change and
Ecosystems.  A Synthesis of the Present Knowledge, SCOPE 29.  New  York:
John Wiley and Sons, pp. 393-473.

Webster, A.J.F.  1981.  Weather and infectious disease in cattle.  The
Veterinary Record 108:183-187.

World Bank.  1988.  World Population Projections. 1987-1988 edition.
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World Food Institute.  1987.  World Food Trade and U.S. Agriculture,
1960-1986.  Aces, IA: Iowa State University.
                                  10-51

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                            CHAPTER 11

          THE POTENTIAL IMPACT OF RAPID CLIMATIC CHANGE
                 ON FORESTS IN THE  UNITED  STATES
FINDINGS
Global warming could significantly affect the forests of the
United States.  Changes could be apparent in 30 to 80 years,
depending upon the region, a site's quality, and the rate of
climate change.  There may be northward shifts in species ranges,
dieback along the southern reaches of species ranges, and changes
in forest productivity.  The combined effects of climate change
and other stresses may exacerbate these impacts.  Different
migration rates and climate sensitivities may result in changes
in forest composition. Large reductions in the land area of
healthy forests are probable during this century of adjustment to
climatic changes.

Range Shifts

o    The southern ranges of many forest species in the eastern
     United States could dieback as a result of higher
     temperatures and drier soils.  The southern boundary could
     move several hundred to one thousand kilometers (up to six
     hundred miles) in a generally northward direction for the
     scenarios studied.

o    The potential northern range of forests species in the
     eastern U.S. could shift northward as much as 600-700 km
     (370-430 mi) over the next century.  Actual northward
     migration could be limited to as little as 100 km (60 mi),
     due to the slow rates of migration of forest species.  It
     could take centuries for eastern forests to fully migrate to
     potential northern distributions.  If climatic change is too
     fast, some tree species may not be able to form healthy
     seeds, thus halting migration.

o    If elevated C02  concentrations substantially  increase the
     water-use efficiency of tree species, the southern declines
     could be alleviated.

o    If climate stabilizes,  forests might eventually regain a
     generally healthy status (over a period of several
     centuries).   In the meantime, declining forests could be
     subject to increased fires, pest attacks,  and replacement
     with low-value trees, grasslands, and shrubs.

     Productivity Changes

o    Dieback along the southern limits of distribution of many
     species could result in productivity declines of 46 to 100

                              11-1

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                                                          Forests
     Productivity Changes

o    Dieback along the southern limits of distribution of many
     species could result in productivity declines of 46 to 100
     percent, depending on how dry soils become.

o    Productivity could increase along the northern limits of
     some eastern tree species, particularly as slow-growing
     conifers are replaced by more rapidly growing hardwoods.

     Combined Impacts with Other Stresses

o    Large regions of severely stressed forests, combined with
     possible increases in fires, pests, disease outbreaks, wind
     damage, and air pollution could produce major regional
     disturbances.  These factors were not considered for this
     study.

o    Additional impacts of changes in forests include reductions
     in biotic diversity, increased soil runoff and soil erosion
     reduced aquifer recharge, changes in recreation, and changes
     in wildlife habitat.

Policy Implications

o    Institutions such as the U.S. Forest Service, state forest
     agencies, and private companies should begin to consider how
     to factor climate change in their long-term planning.
     Global climate change may need to be a factor in the Forest
     Service's 50^-year plan.

o    Strategies that forest agencies may wish to consider.include
     the feasibility of massive reforestation on a much larger
     scale than practiced now, and the possible introduction of
     subtropical species into the Southeast in order to maintain
     U.S. forest productivity. A coordinated public and private
     reforestation effort, together with development of new and
     adapted silvicultural practices, may be required.  A large
     reforestation program would also reduce atmospheric C02
     concentrations, slowing the rate of global warming.
EXTENT AND VALUE OF U.S. FORESTS

     Forests occupy 33% of the U.S. land area and exist on some
lands in all 50 States.  In total, they occupy 299 million
hectares (738 million acres)  and are rich in such resources as
water and wildlife.

                               11-2

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Chapter 11
     Many biotic and abiotic factors influence the condition  of
forests, but climate is the dominant factor  (Spurr and  Barnes,
1980).  This chapter summarizes what is currently known and
predicted regarding the effects of rapid climatic change on U.S.
forests.

Distribution and Ownership

     Eight major forest regions of the conterminous 48  States
contain 84% of the forested ecosystems of the United States
(Figure 11-1).  The forested areas of Alaska and Hawaii represent
the remaining 16%  (Table 11-1).  Each forest region includes  one
or more forest types distinguished by the major tree species
present.  As a general rule, some types in each region  have
predominantly coniferous tree  species (i.e., evergreen,  needle-
leaved, and softwoods); other  forest types are composed mostly of
deciduous trees (i.e., tree species that are broad-leaved, have
no winter foliage, and are hardwoods).  Forest types with a mix
of coniferous and deciduous trees, however, are not uncommon.

     Superimposed over the natural distributions of trees,
forests, and ecosystems in the United States is the human
infrastructure.  Ownerships include Federal, State, and private
lands  (Table 11-1).  In broad terms, the United States  contains
public forests (28%), private  industry lands (14%), and many
small private forests or woodlands (58%) that mostly consist  of
parcels less than 200 hectares (ha) (about 500 acres)  (Woodman,
this report).  The Federal Government ownership of 40 million ha
(99 million acres) of commercial forest lands is primarily in the
National Forest System managed by the U.S. Department of
Agriculture's Forest Service (36 million ha or 91 million acres);
most of the remainder is managed by the Department of Interior's
Park Service, Fish and Wildlife Service, or Bureaus of  Land
Management and Indian Affairs.  State ownerships total  9 million
ha (23 million acres).  Private lands are divided between those
of industrial forest companies (27 million ha or 68 million
acres)  and small landowners, who collectively have 112  million ha
(277 acres).

     To the degree that all forest lands are owned by some
individual or organization, all forest lands are under  some form
of management.   A continuum of management policies exists,
ranging from those lands intended to have minimal human
intervention, except for protection from catastrophic wildfire
(e.g.,  some parks and most wilderness areas), to lands  where
silvicultural practices are intensively applied (e.g.,   the most
productive Federal, State,  and industrial forest lands  dedicated
to growing tree crops," Table 11-2) .  The forests under  government
and industrial management constitute roughly one-fourth  of the

                               11-3

-------
 (0


•H
 ^
 Oi


 i-l
•H
 0)
T3
 C
 W
 (U
P
 (0
4J
W

•O
 0)
4J
•H
 c
p
 O
 c
•H
 0)
 -p
 c
 O
 u

 0)
 en
 c
 o
•H
 fr
 0)
 -P
 M  0
 0)  P<


 o  o
 O  0)
 •r-i 0)
 (0  M
 S FH
 I
cH
i-l
 0)
 fa

-------
        Chapter 11
  Table 11-1.  Area  of U.S.  forest lands  in  1977 by federal,  state,  private,
               and other ownerships  (millions  of hectares ;  USDA, 1982).
                                                  Commercial Forests
Region/States Primary Tree Species Federal State
EAST










Northeast -
CT, MA, ME, NH, RI, VT
Lake States -
MI, MN, WI, NO, SD(E)
Central -
DE, IA, IL, IN, KA, KY, MD,
MO, NB, NJ, OH, PA, TN, WV
Southeast -
AL, AR, FL, GA, LA, MS, NC,
OK, SC, TN, TX, VA
spruce-fir
maple-beech-bi rch
spruce-fir
maple-beech-bi rch
map I e- beech -birch
oak-hickory

loblolly, shortleaf
stash pine

i
0.3

2.3

1.8


5.8


0.4

2.8

2.0


1.0

Private
Non-
Industry Indus
3.9

1.7

8.6


14.7

I
7.8

9.9

22.9


54.3

%
Others3 Total Tota
0.7

4.2

2.6


8.0

I
i i i
13.1 j 4.4
I
20.9

37.9


83.8


7.0

12.7


28.1


! I

•



Northern Rockies -
ID, MT, SD(W), WY
Southern Rockies -
AZ, CO, NM, NV, UT
Pacific Northwest -
OR, WA
California - CA
pine-fir-birch
pinyon- juniper- pine
0. fir-hemlock-fir
pine- fir- redwood
9.1
6.4
7.8
3.4
0.6
0.3
1.2
.03
0.8
0.0
4.0
1.1
2.7
2.4
3.2
2.0
9.3 | 22.5 | 7.6
I I
i |
24.1 | 33.2 |11.1
1 1
I
5.3 | 21.5 | 7.2
I I
9.8 | 16.3 | 5.4
i i

SEPARATE
STATES
.
Alaska - AK
Hawaii - HI
spruce- hemlock-hardwood
ohia
' 3.3
.01
1.0
0.2
0.0
0.0
0.1
0.2
43.9 | 48.3 |16.2
I I
0.4 | 0.8 j 0.3
i i
                             TOTAL
                             TOTAL
40.2
13.5
9.5
3.1
34.8
11.7
105.5
 35.4
108.3
 36.3
298.3
100
                                                                                100
1  Hectare x 2.47 = acres

2  Commercial forests  are  those capable of  growing at least 1.4
  m3/ha/yr (20 ft3/ac/yr)  of  industrial wood materials.

  Other forests include county and municiple  forests and those
  federal lands withdrawn from  industrial  and wood production for
      as parks, preserves, and  wilderness.
Source:  USDA  (1982) .
                                        11-5

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                                                          Forests
Table 11-2.  Percentage of Forest Lands by Level of Management
             Within Four U.S. Regions.  (Estimates for 1977
U.S. Region
                  Forest
               Plantations3
                                   Other
              Reserved/
Commercial    Deferred
East
   North
   South
                      9
                     21
    80
    69
11
10
West
   Rocky Mountains    2
   Pacific Coast     16
                                     38
                                     44
                 60
                 40
alntensively managed plantations.
Moderately managed forests.
C0ther commercial.

Source:  USDA (1982).
                               11-6

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Chapter 11
total and might be the easiest to manage under climatic impacts
simply because they are larger blocks of lands already under
strong management commitments.

Value of U.S. Forests

     Most populated regions in the United States are located
close to or within a forested region.  For instance, the Boston-
Washington corridor is within the eastern hardwoods.  Atlanta and
Southeast populations are interspersed among the southern pine
forests.  Chicago and nearby Great Lakes communities are
surrounded by the mixed conifer-hardwood forests of that region,
and the Los Angeles to San Francisco populations parallel the
Sierra Nevadas to the east.  Forests, therefore, are .part of the
environmental fabric and general habitability for the majority of
U.S. citizens.

     All forests shed water to some degree, and two-thirds of the
water runoff in the contiguous 48 States comes from forested
ecosystems.  Precipitation passes through forested ecosystems as •
canopy throughfall and flows in or along tree stems, the ground
surface, and the soil; eventually, some precipitation flows into
streams.  Water yields from U.S. forests provide about 750
billion liters (200 billion gallons) of water per day for major
uses such as irrigation (47%), steam electric (26%),
manufacturing (15%), and domestic use (6%).  These levels of
demand are projected to continue to the year 2030  (USDA, 1981).

     A favorite use of forests is outdoor recreation.  Activities
include hiking,  camping, hunting, sightseeing, boating, swimming,
fishing, skiing,  sledding, and snowmobiling.  A 1977 survey of
U.S. households indicated that a majority of people participated
in outdoor recreation four or more times per year  (USDA, 1981).

     About 190 million ha (470 million acres), or 64% of the
total U.S. forested ecosystems, are highly productive commercial
forest lands.  These lands represent about 10% of the world's
forest area, but they supplied nearly a quarter of the world's
industrial forest products in the late 1970s (USDA, 1982) .  In
1980, 1.7 million people were employed in timber-based
occupations across the United States.  Such employment is basic
to the economic well-being of many small towns and communities
(Schallau, 1988).   The total value of timber products harvested
in 1972 was about $6.4 billion, and the total value after such
processes as manufacturing,  marketing, transport,  and
construction amounted to $48 billion, or 4% of the nation's gross
national product.   In 1979,  timber product exports and imports
were valued at $7 and 9 billion, respectively.  Looking ahead,

                               11-7

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                                                          Forests
the consumption of wood products in the United States is
projected to increase between current levels and the year 2030
(USDA, 1982).
RELATIONSHIP BETWEEN FORESTS AND CLIMATE

     Scientific understanding of forest ecosystems has greatly
advanced with each decade of this century.  Yet the literature
contains little information concerning the direct or indirect
effects of climate change on the complex of biological and
physical processes in forest ecosystems.  Some insights are
gained from paleobotanical studies regarding past rates and
magnitudes of change during glacial-interglacial cycles, as well
as changes in forest composition.  Similarly, observations of
forest responses to unusual drought or other weather extremes
provide some knowledge.  Estimates of rate, magnitude, and
quality of change have also been derived using computer models
developed by plant ecologists or forest management scientists for
other objectives.  Their validation for understanding how.a
forest can adapt to climatic change is only in the initial
stages.

     Climate is a primary determinant of existing forests.  The
ranges of annual average temperature and rainfall variation
determine global forest distributions relative to different
biotic regions (Figure 11-2).  Substantial increases in
temperature or decreases in rainfall could, for example, produce
a shift from a forest to a grassland type.  Thus, accelerated
climatic change resulting from human activities and related
effects on U.S. forests is of high concern to citizens and
policymakers alike.

Magnitude

     As pointed out by Spurr and Barnes (1980), there is ". . .
irrefutable evidence that vegetation (i.e., ecosystems) has been
in an almost constant state of instability and adjustment due to
an almost constantly changing climate over the past 10,000 years
and even over the past several hundred years .  . . ."  Lines of
evidence come from studies of fossils,  tree rings, carbon-14
dating, plus peat and pollen analyses (Barbour et al., 1987).

     Historical climatic changes appear to have been associated
with such phenomena as fluctuations in solar radiation, earth
orbit variations, and volcanic activity.  Evidence of repeated
continental glacial advances and contractions in the Northern
                               11-8

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Chapter 11
Hemisphere dramatically illustrates the large-scale effects of
global climatic change.

     In response to the glaciation, ecosystems shifted south.
Evidence from fossil pollen, for example, indicates a southward
shift of spruce into Georgia and east Texas during the last
glacial advance and treeless tundra in the Great Lakes States
(Spurr and Barnes, 1980).  During the maximum interglacial warmth
of 6,000 to Figure 11-2. Approximate Distributions of the Major
World Bioass Based Upon Mean Annual Temperature and Precipitation
(Hammond, 1972) 9,000 years ago, which was 1.5°C (2.7°F) warmer
than the present temperature level, plant zones were one to
several hundred km (60-250 miles) north of present distributions.

Rates

     All forested ecosystems experience change on both spatial
and temporal scales; each biological and physical forest
component may respond to climatic variation on different spatial
and temporal scales.  For example, microorganisms, insects, and
birds come and go with relatively short-term climatic variation;
shrub species abundances vary within the timespan of decades;.
trees, once established, could persist for centuries.  This
understanding is important from the perspective of climatic
change, since it implies that forested ecosystems do not respond
as a unit, but in terms of parts.  Different parts respond
differently; consequently, future forested ecosystems under a
rapidly changing climate could be quite different from those
existing today.

     At the expected rapid rate of climatic change, the potential
rates of forest migration would become a major concern.
Migration rates vary by species.  Paleorecords of the Holocene
(10,000 years ago to present)  show that extension of ranges for
tree species of eastern North American (in response to glacial
retreat) varied from 10 to 20 km (6 to 12 miles)  per century for
chestnut, beech, maple, and balsam fir (Zabinski and Davis, this
report).  Other species within the oak and pine groups extended
at faster rates, i.e., 30 to 40 km (19 to 25 miles) per century.

Mechanisms

     Knowledge of causal links between weather patterns and
forest response is fundamental to projecting growth and
composition effects resulting from climate change.   Another
requirement is to understand the climatic influences on
population processes of forest plants and animals.   These include
such phenomena as fires, windstorms,  landslides,  pest outbreaks,

                               11-9

-------
Ul
e

-------
Chapter 11
and other disturbances that affect survival and subsequent
colonization by different species.  Furthermore, the processes
that control the dispersal of seeds through a mosaic of different
ecosystem types (such as forest patches interspersed with
agricultural lands, wetlands, grasslands, and other land-use
groups) must be clearly defined.

     Among the important factors now known to influence the
growth and distribution of forests are the following.

Temperature

     The optimum temperature for growth depends upon the tree
species and other conditions.  Warmer temperatures usually
increase the growth of plants.  However," very high temperatures
decrease the growth of plants or kill those growing at optimum
(or higher) temperatures.  Cold temperatures can limit plant
distributions by simply limiting growth at critical stages or by
directly killing plants.

Precipitation

     Too much or too little precipitation can limit forest
production and survival.  Too much rainfall in some areas can
cause flooding or raise the water table, thus drowning roots that
require oxygen or promoting fungal attack.  Too little rainfall
can reduce growth, cause susceptibility to fire or pestilence,
and possibly kill plants.  The seasonal timing of rainfall is
more important than total annual rainfall, although forests also
require some minimum total annual rainfall (see Figure 11-2).

CO2 Concentration

     High CO2  concentrations  could increase tree growth through
increases in photosynthesis rates and water-use efficiency
(primarily hardwood species)  when water and other nutrients are
not limited (Strain and Cure, 1985).   Plant responses to CO2 have
been investigated largely in growth chambers and are difficult to
extrapolate to the real world.  Responses are varied and do
indicate some measure of adaptive capability most likely imparted
from ancestral exposure to much higher and lower levels in the
geologic past.  However, in natural situations,  water nutrients
or temperature usually are limiting factors in forest growth,
thus making the impacts of C02 enrichment  uncertain.   If water
use efficiency increases, then tolerance to drought might
increase,  ameliorating declines in southern parts of ranges.
Unfortunately, the current state of knowledge does not allow
generalizations on this subject.

                              11-11

-------
                                                          Forests
Light

     The amount of sunlight bathing an ecosystem sets the upper
limit on net primary productivity.  Thus, the tropics exhibit
higher productivity than do the boreal regions.  This potential
productivity would, of course, be limited by other climatic
effects such as drought, cold, heat, and natural disturbances,
and the time required for forests to shift into new ranges.  The
length of day exerts considerable control on physiological
processes such as release from and onset of dormancy.
Significant northward shifts of forests would alter their day
length regime, producing uncertain results.

Nutrient Status

     In addition to climate, most forest growth is strongly
influenced by availability of soil nutrients.  Disturbances over
vast regions, such as by drought followed by fire, can release
large quantities of essential nutrients into the atmosphere and
surface waters and can make soils deficient.  Lengthy periods of
soil development are usually required to replenish the soil          £
nutrients before a large, mature forest stand can be supported.      ^
In turn, soils reflect properties of the forests that they
support.  This results from decades of nutrient uptake,
litterfall, decomposition, and other processes.

Atmospheric Chemistry

     Much of the nutrient budget of forests involves deposition
of chemicals from the atmosphere as gases, aerosols, particles,
and in solution.  Although most of these act as nutrients, some
produce acid deposition that can leach important soil nutrients
(e.g., SCvf) , produce a fertilizing effect  (e.g., NOs"', or damage
leaf tissue  (e.g.,  Oj) .   Climatic  change  will alter transport
paths of air pollutants, and increased temperature could increase
the rates at which gases convert to deleterious forms.

Disturbances

     Almost continually, forests experience natural disturbances
or stresses from biotic or abiotic agents alone or in
combination.  Examples are insects and disease outbreaks, plant
competition, wildfire,  drought, cold extremes, and windstorms.

     These disturbances, which are among the primary factors
controlling the successional processes in forests  (Pickett and       ^
White, 1985), may range from an opening of small gaps in the         ^
canopy as the result of single tree death or of windthrow

                              11-12

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Chapter 11
occurring when trees are blown down by heavy winds  (predominant
successional mechanisms in eastern hardwoods), to large clearings
from fire, windthrow, or pestilence  (predominant successional
mechanisms in western forests).

Landscape Processes

     The horizontal movement of material and disturbances through
the landscape is critical to the processes controlling forest
migration, species diversity in forests, and the spread of fire,
windthrow, and pestilence effects.  These processes are very
poorly understood; quantification in the emerging field of
landscape ecology is just beginning.

Multiple Stresses

     In general, trees or forests stressed by one factor, e.g.,
accelerated climatic change, are more susceptible to natural
stresses (secondary disturbances) such as insects, disease, or
invading weed species.  The concept of multiple stresses leading
to forest declines is becoming more widely recognized (Manion,
1981).  Regional climatic changes, even if temporary, frequently
predispose forests to damage by other natural or anthropogenic
stresses.
PREVIOUS STUDIES ON THE NATIONAL EFFECTS OF CLIMATIC CHANGE ON
FORESTS

     Concern regarding effects of climatic change on- U.S. forests
has prompted several excellent reviews.  One of the most
comprehensive  (Shands and Hoffman, 1987) was the result of a
conference sponsored by EPA, the National Forest Products
Association, and the Society of American Foresters.  While
pointing out the high uncertainty associated with current
predictions of climatic change, several authors suggested that if
predictions are true, distributions of key forest species in the
United States will change significantly.

     Other recently produced compilations broadly consider forest
effects, such as in agriculture, prairie land, and the Great
Lakes (White, 1985; Titus, 1986; Meo, 1987; Tirpak, 1987).  These
reviews are largely pioneering efforts and some overlap occurs,
but each presents some key points.

     The methods used in the previous studies are quite similar
to those used in this report.  They include computer modeling of
forest processes, literature surveys, studies of fossil evidence,

                              11-13

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                                                          Forests
and empirical relationships constructed by experts.  The
estimates of future change produced from these studies are
generally based on the output of one or more of the General
Circulation Models used for this report.  Thus, the results of
the previous studies are consistent with those reported here.


STUDIES IN THIS REPORT

     Six studies on forest effects contributed to the regional
case studies reported in this volume.  The purpose was to use
existing methods and data bases to protect U.S. forests from
predicted climatic change.  The selection of the six studies was
based upon three criteria: use of available technology; testing
hypotheses focusing on causal mechanisms; and a mix of studies
that complemented each other, such that the strengths in one
approach might overcome the weaknesses of another.

     This report focuses primarily on forests within the lower 48
States.  It is worth noting, however, that the largest magnitude
of warming is expected in the northern latitudes encompassing the
boreal forest and other forest types in Alaska and Canada.  These
large forests could be under significant risk from climatic
warming.

Study Design

     Characteristics of the six studies are briefly listed in
Table 11-3.   With the exceptions of the Overpeck and Bartlein
study and the Woodman study, the methods are discussed in the
regional case study chapters and will be mentioned only briefly
here.

     Two studies used correlations between tree distributions and
climate (Overpeck and Bartlein; Zabinski and Davis).   Overpeck
and Bartlein's approach consists of correlating the modern pollen
distributions of important tree species with January and July
mean temperature and annual rainfall.  The correlation is then
tested by reconstructing past pollen distributions from General
Circulation Model simulations of past climates (during the most
recent glacial-interglacial cycle) for each species and comparing
them to observed pollen distributions from those periods.  Future
pollen distributions are then constructed from the expected
doubled CO2  climate  projected from the  different model  climate
scenarios.  The correlations are constructed on modern pollen
distributions, rather than tree distributions, to allow the
direct comparison to fossil pollen data.  Modern pollen
distributions are similar to, but not exactly the same as, modern

                              11-14

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Chapter 11
Table 11-4,
Principal Investigators,  Regional Focus and Method
of Approach for the Regional Forested Ecosystem
Studies
Principal Investigator
                Region
     Method
Overpeck and
Bartlein

Urban and Shugart
Botkin et al.


Zabinski and
M. Davis -

Davis

Woodman
           Eastern North
            America

           Southeast Uplands
           Great Lakes
           Great Lakes
           California

           Southeast,
            California,  and
            National
Correlation and
 fossil studies

Forest dynamics
 model

Forest dynamics
 model

Correlation
Fossil studies

Literature
 review
                              11-15

-------
                                                          Forests
tree distributions.  The verification studies indicate that the
approach works reasonably well at a coarse spatial resolution.
That is, northern trees are in the north and southern trees are
in the south, with the regional patterns being reasonably well
represented.

     The approach of Zabinski and Davis is essentially the same
as that of Overpeck and Bartlein, except that the correlations
are constructed from the actual modern tree distributions rather
than  from the modern pollen distributions (see the Great Lakes
chapter of this report).

     Two of the studies used computer models of forest dynamics
(Botkin et al.; Urban and Shugart).   Both studies explored forest
response on a range of soil types from well drained to poorly
drained.  Forest growth simulations from bare ground represent
conditions after a fire, logging, or similar disturbance.  Mature
stand simulations are useful for investigating the potential
response of present forests to gradual climatic change in the
immediate future.

     For the California case study,  Davis reconstructed
vegetation patterns in the Sierra Nevadas from fossil pollen
studies for the interglacial warm periods between about 6,000 and
9,000 years ago.  These reconstructions represent possible
analogs of a future warm period at the lower magnitude of the
predicted future warming.

     A literature review was conducted by Woodman for the
Southeast and California forested regions and peripherally for
the nation as a whole.  The purpose was to ascertain the
attributes of the forest resource in terms of extent, ownership,
economic and recreational value, and policy considerations.

Study Results

     The six studies conducted by EPA are consistent enough to
indicate that climatic changes would significantly affect the
natural forests of the United States.  The distribution of
healthy forests in the eastern United States appears to become
greatly reduced from their areas during the next century (see
Figure 11-3 and 11-4).  This results from a very slow northward
migration coupled with a fairly rapid decline in the southern and
western parts of species ranges.  Drier forest conditions in the
United States, induced as much by increased temperature as by
changes in rainfall, would mean less tree growth and therefore
reduced forest productivity in general.
                              11-16

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    Simulated by Observed Modern Climate
      Spruce    Birch
           N. Pines     Oak
         S. Pines    Prairie Forbs
    Simulated by GISS Model Output
    Simulated by GFDL Model Output
    Simulated by OSU Model Output
      Spruce    Birch
           N. Pines
Oak
S. Pines   Prairie Forbs
Figure  11-3.
Present  distribution  of  major forest  genera and
herbs vegetation of eastern N. America compared  to
potential  future distributions after  reaching
euilibrium with the climate predicted for 2xC02.
The comparison is based  upon simulated modern
pollen data (a) and simulated future  pollen
abundances for each of the three 2xC02 scenarios:
(b) GISS;  (c)  GFDL; and  (d)  OSU  (Overpeck and
Bartlein,  Volume _).
                                11-17

-------
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Chapter 11
     The forest simulation models provide an indication of the
importance of uncertainties imparted by the climate scenarios.
The climate scenarios differ primarily in their representation of
regional rainfall patterns.  The model results indicate that
temperature has a large effect on forest health, either directly
through cold and heat stress or indirectly by exaggerating
drought effects.  Thus, the overall characteristics of forest
responses are remarkably similar among the three climate
scenarios.

Magnitude

     Eastern Forests - Northern Limits

     All of the study results suggest a northward expansion of
most eastern tree species  (Figure 	 displays results from
Overpeck and Bartlein).  That is, spruce, northern pine, and
northern hardwood species would move north by about 600-700 km
(375-440 miles) into the Hudson Bay region of the Canadian boreal
forest (Overpeck and Bartlein; Zabinski and Davis).  New England
coniferous forests would be replaced by more hardwood forests and
especially by the oak. species from the eastern mid-United States
(Botkin et al.; Overpeck and Bartlein; Zabinski and Davis).  As
the northern mixed forests shift from spruce-fir to sugar maple,
some sites could actually triple their present productivity
(Botkin et al.).

     Additionally, southern pine species could shift about 500 km
(310 miles)  into the present hardwood forest lands of eastern
Pennsylvania and New Jersey (Overpeck and Bartlein; Urban and
Shugart; Solomon,  1986; Miller et al., 1987).  Depending upon the
severity of climate change, Urban and Shugart estimate that near
the northern limits of slash pine in East Tennessee, above-ground
woody biomass in 100 years could range from little change to
extremely low biomass with no trees supported (i.e., a grassland,
savanna, or scrub).  However,  even with little decrease
in productivity, species shifts would alter the forest
composition from shortleaf to loblolly pine, a more commercially
valuable tree species.

     Eastern Forests - Southern Limits

     Ultimately, forest decline and mortality could truncate
southern distributions of tree species by as much as 1,000 km
(625 miles)  in many northern hardwood species (Zabinski and
Davis; Overpeck and Bartlein)  or by as little as a few hundred km
(60 miles)  in southern pines and hardwoods (Urban and Shugart;
Solomon and West,  1986).   Under the driest scenario, Zabinski and

                              11-19

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                                                          Forests
Davis predict local extinction in the Great Lakes region of many
eastern tree species such as eastern hemlock and sugar maple
(Figures 11-3 and 4).   These estimates bear considerable
uncertainty for all species.

     These uncertainties are particularly true for the southern
limits of southeastern species that border the continental
margin.  The actual southern climatic limitations of these
species are not well known  (Urban and Shugart).   Nevertheless,
under the most severe climate scenario in the Southeast with
increased temperatures and decreased growing-season
precipitation, Urban and Shugart's results suggest that the 18
tree species they considered would no longer grow in the southern
half of the region.  Present forest lands in the region would be
replaced by scrub, savanna, or sparse forest conditions.  Under
the most mild scenario, much of the southern half of the
Southeast would not support trees, and areas in South Carolina
would be marginal, supporting about half the current biomass of
forest.

     Biomass accumulations in 100 years for mature natural
forests in productive sites in the Lake States could be reduced
to 23-54% of their present values (Botkin et al.; Solomon and
West, 1986).  On poor sites, forests could be converted to
grassland or savanna with very low productivity, ranging from 0.4
to 28% of their present values.

     Western Forests

   .  Similar projections were made for six western coniferous
species:  ponderosa and lodgepole pine, Douglas-fir, western
hemlock, western larch, and Englemann spruce (Leverenz and Lev,
1987) .  Predictions are mixed for the West.  Because of the
mountainous conditions in the West,  upslope shifts are possible
for Douglas-fir, ponderosa, and western hemlock in the northern
Rocky Mountains.  In the coastal mountains of California and
Oregon, Douglas-fir should shrink in the lowlands and be replaced
by western pine species (Davis, this volume; Leverenz and Lev,
1987).  Overall, the western forest lands are predicted to favor
more drought-tolerant tree species,  such as the hard pine group,
at the expense of fir, hemlock, larch, and spruce species.

     If regional drought persisted,  the frequency of fires could
increase, significantly reducing total forested area.  Also, with
massive upslope movement,  some species would be pushed off the
tops of mountains into local extinction.
                              11-20

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Chapter 11
     No quantitative estimates have been derived for productivity
for the western forests under potential, warming conditions.
However, using the analog approach of Davis, under the most
severe conditions projected for California, the species
composition of the west-side Sierra Nevada forests would become
more similar to that of the east-side forests.  This would reduce
the standing biomass to about 60% of current levels.

Rates of Decline and Migration

     In the Great Lakes region, significant forest decline and
forest compositional change could become evident within 30 to 60
years.  In the Southeast region, forest declines could become
evident in 60 to 70 years, with declines in the drier western
portions occurring even earlier, perhaps in about 30 years
(Figure 11-5) (Urban and Shugart).

     These rapid declines, coupled with the expected magnitude of
change, raise the question of how fast forests can migrate.
Based upon .fossil records, Zabinski and Davis have estimated that
the maximum dispersal rate of several tree species in response to
the last glacial retreat was roughly 50 km (30 miles) per
century.  Under the expected rapid warming, they estimated that a
dispersal rate of about 100 km (600 miles)  per century would be
required to maintain species distributions near their current
extent.  Such migration routes are doubtful, suggesting greater
reductions in species ranges under rapid climatic changes.
Mechanisms of Migration

     Distribution changes suggested by these studies (i.e.,
migrations) must be considered carefully.  Reproductive processes
are essential for the migration of tree species across the
landscape.  For many tree species, climatic change could reduce
natural regeneration in an existing location and introduce the
species at different latitudes or altitudes.  Reproductive
processes in trees, such as flowering, pollination, seed set,
seed germination,  and seedling competitive success, are
particularly sensitive to climate.

     Specific regional climate scenarios vary as a function of
the GCM.  All scenarios predict increases in temperature;
however, some predict increases in rainfall, and others predict
decreases.  The northward shifts of species appear to result from
a release from cold temperature stress,  which normally freezes
flowers, seedlings, and even adult trees.  However, the western
and southern limits of eastern tree species appear to result from
insufficient moisture stress and excessive heat stress, which
                              11-21

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                      A.   MISSISSIPPI TRANSIENT
                           Dynamic* of Motor* forest
"3"
V
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0
c
0
is
o
0


180-
160-
140-
120-
100-
80-
•0-
40-
20-

<
Woody Biomass
___ No Climate Change
— — Transient Scenario
X
X
X
X
\
\
\
\
\
\
\
\

| | 	 1 1 T "T 1 i '
) to 20 30 40 50 *0 70 80 »
                                 Simulation Y«ar

                     "B.  SOUJH  CAROLINA TRANSIENT

                           Dynamics of Mature Forest
                                                  Woody Biomass

                                                  __ No Climate Change
                                                  — — Transient Scenario
Figure 11-5.
                              JO    «0     50    «O

                                 Simulation Year
Projected  changes in biomass  (T/ha=2.24 t/acre)  of
mature  forests in Mississippi  (A)  and South
Carolina  (B)  under the GISS transient climatic
change  scenario (Chapter 	; Urban and
Shugart, Volume _),  shifts toward drier conditions
and the prairie advances to the East.  Presumably
changes in western forests would result from
similar mechanisms.   The drought-induced declines
in forests might be partly offset if C02-induced
increases  in  water-use efficiency were realized.
                                11-22

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Chapter 11
primarily affect sensitive life history stages but can also
affect adult trees.

     All of the study approaches used under all of the climatic
scenarios predict major forest declines in the southern parts of
species ranges and expansions to the north.  These declines,
resulting primarily from drought stress, would occur despite the
differing rainfall predictions.  Increases of temperature would
severely reduce water intake, and therefore, would produce
drought.  Although precipitation could increase slightly in some
U.S. locations, generally the increased evaporative demand caused
by higher temperature would be a greater factor.  Subsequent
differences in rainfall between the various climate scenarios
would modify the magnitude of regional drought patterns.  The
western limits of eastern forests could similarly retract as the
climate.  Existing forests probably would not shift intact, but
would change in composition,  variations in migration rates and
sensitivities to weather variables produce individual responses
to climate change.  These changes are consistent with the well-
known dynamic nature of ecosystems and were projected for the
forests of all regions.  In the Great Lakes region, for example,
beech would decrease in abundance, and birch and maple would
increase (Zabinski and Davis; Botkin et al.).  On some lands,
forest productivity could remain about the same as today, but
changes to less economically important species could be
significant.

     Not considered quantitatively in any of the studies are
changes in forest disturbance regimes.  These changes should not
be considered lightly.  Extreme and more frequent climatic
variations (see Chapter 17)  could cause much higher mortality in
U.S. forests than the current experience.  Although little is
known as yet,  some locations may experience an increase in the
frequency of extreme weather events, for example, wind, ice, or
snow storms, droughts, and flooding.  Besides the direct damage
these events can cause, they can cause drainage from insects,
disease, and wildfires.

Study Limitations

     Although predicted effects vary, these six analytical
studies have results that are collectively consistent enough to
advance our knowledge and justify concern regarding the future of
U.S. forests under rapid climate change.  The range of predicted
effects is large; however,  uncertainties exist regarding (1) the
climate scenarios; (2) the kind and rates of responses of
individual tree species; and (3)  changes in forested ecosystems
as a whole from environmental change.  All of these factors

                              11-23

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                                                          Forests
significantly influence the precision and accuracy of the
results.

     A major uncertainty in the simulation model approach
involves the rates of species dispersal into a region.  The
current generation of models has no dispersal mechanisms.  A
species is simply present or it is not present.  For example,
Botkin et al. excluded more southern tree species so that their
dispersal was unrealistically nonexistent, and these southern
species could never enter the region.  But if they had been
included in the simulations, these species would have entered the
northern forests at the same rate as the climate change.  This
would have assumed dispersal rates far in excess of reality.
This limitation can, in part, be overcome by studies, such as
those of Zabinski and Davis, that provide some insight into
actual dispersal rates and species migration.

     The models also carry assumptions about the environmental
controls of species limits.  In most cases these assumptions are
reasonable, given that the assumed control {for example, July
temperature or annual rainfall) is usually related to the actual
control, perhaps accumulated warmth or summer drought.  However,
large uncertainties exist in some instances.  This is
particularly true with regard to the climatic controls of the
southern limits of southeastern forests, simply because of their
association with the continental margin.  Does the climate at
that latitude represent the actual climatic limitation to the
distributions, or are the species simply stopped by a geographic
barrier?  No one really knows.  These uncertainties were
partially addressed by Overpeck and Bartlein, who compared their
fossil pollen approach to the modeling approach.  The two
approaches use similar relations to climate.  Both approaches can
be used to simulate forest distribution in the geologic past and
both do reasonably well.

     Several uncertainties with the pollen-climate correlation
approach limit its precision and accuracy.  First, many of the
plant taxa used in the study are plant genera (e.g., pine, oak)
rather than species, and thus the simulated results are not
taxonomically precise.  Second, the results are applicable only
on a regional scale; local scale predictions are not made.
Third, and very significant, the simulated results assume that
all the plants are in equilibrium with the new climate.  Rates of
dispersal vary between species, and several hundred years may
pass before plant communities are again in equilibrium with
climate.  How this lag would affect vegetation dynamics is not
addressed in this study and is an important research question.
                              11-24

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Chapter 11
     The paleoecological analysis of the past vegetation  in the
Sierra Nevadas  (Davis) presents several uncertainties.  First,
differences with respect to weather variations  (i.e., season to
season and year to year) could produce strikingly different types
of vegetation.  Also, there is a large uncertainty about  what the
most appropriate analog period might be — or if one even exists!
Furthermore, the rate of climatic change in the future is
predicted to be much faster than the rate of climatic change
during the past 20,000 years.  Lags in the response of species to
the future climate could strongly affect the type of forest at
any one location, whereas in the past, with a more slowly varying
climate, lags in species response were not as important in
determining forest composition.  To the extent that climatic
regimes predicted for the future are similar to the climates of
certain periods in the past, a picture of future forests  can be
estimated from these past periods.

     All of the studies are deficient in some very important
processes controlling forest responses to climate, particularly
disturbance regimes such as fires, windstorms, hurricanes,
landslides, and pest outbreaks.  In addition, the responses of
mature trees to elevated C02 under conditions of moisture,
temperature, or other nutrient limitations remain largely
unexplored.  Most research on elevated C02  on plants  has  been
performed in controlled chambers using seedlings (Strain  and
Cure, 1985).  However, the seedlings were not previously  grown in
or acclimatized to high C02 environments.   Evidence has  shown
that plants grown under high CO2 will  respond much  differently to
changes in temperature, light, and moisture conditions (Strain
and Cure, 1985).  However, our ability to extrapolate C02
fertilization results from laboratory experiments to the  natural
world is limited, and our understanding of regional changes in
water use efficiency is even less.  Furthermore, complex
interactions between fertilization effects and changes in water
use efficiency can produce unexpected problems such as reduced
heat tolerances due to effects on evaporation cooling.  These
interactions are least understood, but could produce major
regional changes in forest responses.   Therefore, it is not yet
possible to quantitatively incorporate the direct effects of C02
on forests into studies such as these.  Further, if water or
nutrients are limiting to forest growth,  then the effects of
carbon fertilization may not be significant.


NATIONAL, ECOLOGICAL, AND SOCIOECONOMIC IMPLICATIONS

     The effects of the predicted climate changes resulting from
a doubling of CO2 by  2030  may  be considered from two

                              11-25

-------
                                                          Forests
perspectives:  ecological and socioeconomic.  Evidence for
significant national implications is strong from both viewpoints.

Ecological Implications

     Ecological implications for forests commonly start with tree
response.  But strong implications also exist in regard to other
ecosystem components, e.g., animals, soils, water, secondary
impacts, and as noted, the atmosphere through which climate
change is mediated.  Forest effects are described in terms of
tree distribution changes and biomass production changes, but
among the other major components, there is a host of interacting
processes.  Thus, significant changes in tree response would be
accompanied by ecological reverberations throughout all the
forested areas of these regions.

Tree distributions and biomass productivity

     Forest migrations to the north in response to rapid warming
in North America during the next century will be likely.
However, significant lag is possible.  Even under the maximum  •
rates of species dispersal estimated by Zabinski and Davis,  .
healthy forest areas may not redevelop for several centuries.
Meanwhile, forest decline would not be under such constraints, so
the extent of healthy forested regions in the United States
probably would be greatly reduced.  Though some locations may
have increased productive potential from a biomass per hectare
standpoint, the large reductions in areas with healthy forests
would likely create a net reduction in forest productivity for
the United States for several centuries.

     Even if a massive reforestation effort were undertaken, the
new forests resulting from species shifts may or may not be as
productive as existing forests.  More northern latitudes or
higher elevations raise other considerations.  Farther north,
days are longer in the summer and shorter in the winter.  At
higher elevations, damaging ultraviolet light intensity is
greater.  All of these conditions could lower forest productivity
below optimum and could hinder reproduction and survival.

     Animals

     A change in the size and relative homogeneity of forests
could influence whether some animals can continue to live in
habitats to which they have adapted.

     Depending upon the species, animal migration can be hindered
by boundaries between forests and other land types or facilitated

                              11-26

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Chapter 11
as animals move along edges.  In turn, some animals prefer young
forests, and others prefer old forests.  Some animals can exert a
profound influence on forest structure and composition through
selective browsing of seedlings, insect attack of different tree
species, and other effects.  All of these factors combine to
influence the regional patterns of biotic diversity of both
plants and animals (see Chapter	).

     Soils

     Soils under warmer climates also would change, though at a
much slower rate than shifts in species distribution.  Optimum
soil conditions for high forest productivity supporting species
at more northern latitudes or higher elevations might take
several centuries to develop.  Furthermore, it is not at all
clear that some northern soils could even support more southerly
species.  The soils of the boreal forest are vastly different
from those under the deciduous forests to the south.

     Water

     Where forests give way to drier conditions (e.g., in the
Great Lakes and California), many lands now serving as watersheds
might be used for a different purpose.  Furthermore, regional-
scale disturbances (such as fire) and applications of chemicals
(such as fire retardants, fertilizers, and pesticides) could
degrade regional water quality and increase airborne toxic
chemicals (see chapter on Water Resources in this report).

     Sea level rise is an additional water impact related to some
forests.  Projections for sea level changes are up to 1 meter (3
feet) in the next century (see Sea Level Rise chapter in this
report).  Many forest lands of high value for timber production
(e.g., in the Southeast) or recreation (in the Northeast,
Northwest,  and California)  are close to ocean coasts.
Inundations, decreases in depth to the water tables, and
saltwater intrusions could trigger rapid forest declines near
these areas.

     Secondary Impacts

     As the southern bounds of forests tend to shift north,
forest decline (sick and dying trees)  could become extreme over
vast areas.   These areas would be highly susceptible to weed
competition, pest outbreaks,  or wildfire.   As forests decline,
species of lower economic value such as chokecherry, as well as
weedy shrubs and herbs,  could invade via wind dispersion.  Under
                              11-27

-------
                                                          Forests
stressful environments, such species are severe competitors to
most commercial tree species.

     Trees experiencing less favorable growth conditions are more
stressed and will be vulnerable to insect and disease attack.
These secondary pest impacts could last "until the most
vulnerable forest stands or tree species are eliminated" (Hedden,
1987).  In addition, the incidence of catastrophic wildfires is
predicted to increase in U.S. forests with higher temperatures.
Simand and Main (1987) estimated an 8% rise in the occurrence of
fires and a 20% increase in fire-suppression costs.

Socioeconomic Implications

     The United States enjoys substantial economic and cultural
benefits from its forests.  Until recently, the nation's forest
managers assumed that these benefits could be sustained by
maintaining forests in a healthy condition (Fosberg, 1988).  This
was achieved, for example, by preventing fires or pest invasions,
avoiding careless use, and enhancing productivity through good
silviculture.

     Beginning with the possibility of damage from regional air
pollution damage to forests, suspected in the 1980s, alterations
of the environment external to forests presented a new concern.
Research and policy discussions to deal with this issue are
ongoing.

     If climate changes as rapidly as predicted, this additional
external influence with its more global dimensions looms as a
possible hazard to forests and their use.  As can be imagined, a
list of potential socioeconomic concerns would be large.  To
provide a brief perspective, three issues are considered.

Quality of the Human Environment

     The forest amenities enjoyed by most U.S. citizens will be
affected according to different forest responses.  In the Boston-
Washington corridor, a composition change from predominantly
hardwood to more pine forests, though ecologically significant,
would probably only superficially affect most people.  In the
Atlanta-Southeast region, the southern pine forests, while
undergoing a gradual expansion of their northern boundaries,
would have less vigor in the remaining stands.  This could raise
their vulnerability to damage by insects and disease, reducing
esthetic values — at least an intermediate impact for most of
the local citizens.  In contrast, drier climates in the Great
Lakes and California regions may cause the loss of some forest

                              11-28

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Chapter 11
lands to prairie or desert conditions, respectively — a severe
change for the people there, not only in their living environment
but also in the whole spectrum of forest land use.

Recreation

     Forests must be in a relatively healthy condition to support
quality recreational use (Clawson, 1975).  Forests undergoing
gradual composition changes might remain healthy, but rapid
changes would most likely cause stressed or declining forests.
Such forest conditions would have less recreational appeal
because of such factors as less pleasing appearance, greater
threat of wildfire, and reduced hunting quality when game
populations change or are diminished.  Furthermore, drier
conditions in U.S. forests would harm recreational opportunities
that depend on abundant water or snow.

Wood Products

     Altered U.S. forest productivity resulting from climatic
change would have obvious major economic impacts.  Significant
yield reductions could lead to unemployment, community
instability, industrial dislocation, and increased net imports of
wood products.

     Reforestation projects could make up for some losses in
forest productivity and artificially advance migrations forced by
climatic change.  Reforestation technology has greatly improved
in recent decades so that success rates also have increased
greatly.  Examples are high-vigor seedlings through improved
nursery practices, genetic selection, and tissue culture.
Improvements in the field include machine planting,
fertilization, and weed control on selected sites.  Results are
evident from the large acreages of plantations established in the
United States in recent decades, particularly with loblolly pine
in the southeast and Douglas-fir in the Pacific Northwest (see
Table 11-5).

     Innovative manufacturing trends should prove to be timely
during times of rapid forest change.  High-strength and durable
products from reconstituted wood (e.g.,  new particle board
concepts,  warp-proof hardwood lumber, paper products of fiber
from multispecies) are now in use or well along in development.
These new methods will lessen the present overdependency on a few
commercial conifer species from stands above minimum size and
quantity (Ince, 1987).  The result will be an ability to use the
timber resources of the future, however they change in
composition.

                              11-29

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                                                          Forests
Table 11-5.
Levels of management within U.S. forests in 1977 as
illustrated by areas in three broad uses within four
major regions.  Intensively managed are represented
by plantations2;  moderately managed are those
forests naturally established but with commercial
rates of growth3;  and forests with  protection as the
primary level of management  (i.e. deferred or
reserved4;  estimated from tables 3.1 and 9.2,  USDA,
1982) .
U.S. Regions
        Management level (millions of hectares1)
        Intensive     Moderate  Protected  Total
      North             3
      South             8
  West
      Rocky Mountain    1
      West Coast        3
       (WA, OR, CA)
                        65
                        69
                        23
                        22
4
7
32
13
72
84
56
38
1.   Ha x 2.47 = acres

2.   Plantations are forests established by seeding or planting,
     generally on the most productive lands, and followed by
     silvicultural tending such as thinning, fertilization and
     weed control until harvest at an economically optimum age.

3 and 4.  Definitions in Table 11-1.
                              11-30

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Chapter 11
NATIONAL FOREST POLICY AND CLIMATIC CHANGE

     Historically, U.S. forest policies have undergone continued
development to meet national change (Young, 1982).  The earliest
policies were adapted by the New England colonies in the 1600s to
regulate overculturing near settlements.  Wood was needed for
fuel and buildings, but existing methods were not capable of long
distance log transportation.  Development of U.S. forest policies
continued and has been particularly intense this century, as the
National forests, National parks, and wilderness areas were
established.

     At present, forest managers are dealing with many additional
policy issues.  Five of these (Clawson, 1975) are important to
climatic change/forest response:

     o    How much U.S. land should be devoted to forests?

     o    How much forest land should be withdrawn from timber
          production and harvest?

     o    How should the Federal forest lands be managed?   (That
          is, the lands under the USDA Forest Service, USDI Park
          Service, Bureaus of Land Management and Indian Affairs,
          etc.)

     o    What constraints (e.g., mandatory forest practices)
          should be placed on forest managers to ensure national
          environmental goals?

     o    Who should pay the additional costs incurred in
          implementing new policies?

     The large array of forest ownerships in the United States
makes development and implementation of forest policy more
complicated than in most countries, where nearly all forests
belong to the government.   The diversity of owners and managers
results in widely divergent goals and objectives.

How Much Land Should Be Forested?

     Changes in forest composition or regional boundaries induced
by rapid climatic change would magnify the complexity of National
forest policy even further.   Lands in forests now would require
review relative to such competing needs as agriculture and
residential use (which would also be adjusting to climatic
change).
                              11-31

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                                                          Forests
How Much Should Be withdrawn From Timber Production?

     Where the productivity of wood is significantly reduced,
increased, or shifted, a policy question that would surely arise
concerns whether forest lands should be reallocated to maintain
timber production.  If so, how should competing forest uses, such
as watersheds, parks, and wilderness, be treated?  How much of
each can the United States afford under changed climatic
conditions?  Should the Federal Government purchase more forest
lands to support all public needs?

     In the short term, forest managers could compensate for some
loss of productivity by improved technology, though at increased
costs.  An example would be establishing more drought-tolerant
plantations through genetic selections, improved nursery stock,
and more intensive silvicultural practices (e.g., weed control
and thinning).  Introducing new species adapted to warmer
climates might be possible in some locations, but this would call
for developing new silvicultural regimes and use methods —
possible, but expensive in time and money.  In the long term, if
growing conditions become extremely difficult on some U.S. forest
lands because of climatic changes, investment in tree crops at
such locations could become unattractive altogether.

How Should We Manage Federal Forests?

     The National forests under the USDA Forest Service are
managed according to a series of complex legal directives and
administrative procedures, beginning with the Organic Act of 1897
(Woodman).  Ultimately, the objective became to manage the
National forests for multiple uses, with timber on a sustained-
yield basis and certain lands set aside as wilderness areas.  The
National Forest Management Act of the mid-1970s requires 15-year
management plans for each National forest subject to public
review.

     Lands managed by the Department of Interior are under
similar mandates.  For example, a congressional act passed in
1976 charged the Bureau of Land Management to manage its 2.3
million ha of forest and range land according to multiple-use and
sustained-yield principles.  Similarly, the National Park Service
is mandated to manage National parks, monuments, historic sites,
and so forth,  for the recreational enjoyment of people.  Such
activities as timber harvesting, hunting, mining, and grazing are
not permitted.  In addition to the Federal Government, most
States, many counties, and some municipalities own forest lands.
                              11-32

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Chapter 11
     The Forest and Rangeland Renewable Resources Planning Act of
1974 requires the Secretary of Agriculture to make periodic
reviews of the nation's forest and rangeland resources.  The act
was amended in 1976 to also require management plans for the
National forests.  In the future, these assessments and planning
efforts should include consideration of the possible effects of
predicted climatic changes.  One key issue is the level of
priority given to maintaining forest health under changed
climatic conditions.  For instance, under more adverse
environments, should National forests be left to decline as a
natural process, thereby losing esthetic values in parks, water
yields from watersheds, and highly productive timber crops?  Or
should silvicultural forest techniques, such as thinning, weed
control, and fertilization, be employed to "save" them?  This
question and others will challenge the fundamental concepts of
the benefits of multiple use and sustained yield of forests.

How Can We Ensure National Goals?

     At the minimum, Federal agencies must plan and act in
concert with the State forest organizations.  In the first half
of this century, the Federal Government attempted to regulate
forest harvests on Federal and private lands.  Development of
this policy did not survive strong public concern and intense
political debate against such policy (Worrell, 1970); the same
sentiment would likely exist today and in the near term.
However, under the influence of rapid climatic change, the nation
may once again have to face the touchy issue of what restraints
or forest practices must be regulated for all public and private
lands.

     Solomon and West (1985) point out that while climatic change
might disrupt forest ecosystems in the future, it is uncertain
whether forest managers could or would be able to apply
silvicultural practices on a scale large enough to maintain the
net productivity of commercial forest lands in the United States.
Some States (e.g.,  Washington, Oregon,  and California) have laws
specifying fire protection requirements, control burn practices,
and reforestation minimums following timber harvests.  Zoning,
permits, licenses,  and various taxation measures also have been
attempted with mixed results.  It is much easier to prevent
owners from destroying forests than to compel them to implement
silvicultural practices.

     To keep pace with the rapid climatic changes projected, the
U.S.  reforestation effort conceivably would need to be doubled or
tripled in size. .In recent years, about 800,000 ha (2 million
acres)/year (approximately 700+ million seedlings)  have been

                              11-33

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                                                          Forests
reforested in the United States (USDA, 1982).   Costs range from
$200 to $700 per ha ($80 to $280 per acre)  depending upon
species, site preparation, plantation density, and planting
method.  Using $500 per ha ($200 per acre)  as a mode, the total
annual expenditure is near $400 million.   About 0.4% of the
commercial land base is reforested annually.  At this rate, it
would take 100 years to reforest 40% of the U.S. forest lands,
assuming no repeat hectares to cover failures or harvests of the
first plantations.

     An expansion on the scale suggested above would require
large investments in seed procurement, tissue culture capability,
nursery capacity, and research to improve knowledge about the
establishment and silviculture of drought-resistant plantations.
Even if the dollar commitments were made, reforestation at this
scale might only be possible if all forest lands were managed by
one organization.  The complex forest ownership pattern in the
United States, therefore, would be an issue to overcome in a
national reforestation program.

Who Should Pay?

      Adjusting forest policies to address the issues arising
from climatic change will most likely raise the costs of using
the nation's forests — whether for water,  recreation,
aesthetics, or timber.  Additional research to answer many new
questions will also require more funds.  A major question will
concern who should pay for these costs.  Land owners?  Forest
users?  Consumers?  All taxpayers?  The answers will come when
better information is available on resulting forest effects,
followed by public debate establishing new priorities for forest
use in a changed climate.
RESEARCH NEEDS

     The forest effects resulting from rapid climatic change are
at present hypothetical.  The change has not yet occurred, and
many uncertainties are associated with the predictions.
Effective policies to deal with new forest effects will require
more information and fewer uncertainties that must come through
forest ecosystem research.  Four broad questions concerning U.S.
forests frame the research needs for the 1990s:  What will the
effects be?  How can they be measured reliably?  How should they
be managed?  How can we ensure that research will be conducted in
a timely fashion?
                              11-34

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Chapter 11
Effects

     What will be the effect on the nation's forest ecosystems if
climatic changes occur as predicted by the middle of the 21st
century?  While subsets of this question must include extent,
magnitude, and risk considerations, additional knowledge is
needed concerning the following factors:

     1.   Forest migration processes and rates, including the
          landscape processes that control the horizontal
          movements of forest, animals, and disturbances;

     2.   Interactions among the different landscape components
          and land-use practices that affect biodiversity, and
          water quantity and quality;

     3.   The impact of climate change alone and in combination
          with other natural or anthropogenic influences, such as
          insects, pathogens, C02  enhancement,  air pollutants,
          UV-B radiation, and acid deposition on U.S. forests;
          and

     4.   The processes and mechanisms that play key roles in
          forest ecosystem effects — both biologically as in
          photosynthesis and respiration, and physically as in
          flows of energy, carbon, water, and nutrients through
          ecosystems.

Methods

     How can forest ecosystems be measured to reliably detect the
effects of rapid climate change?  Today, the response of
ecosystems to environmental change is largely based upon
extrapolating from field observations, from knowledge about
seedlings or individual trees of a small number of commercially
valuable species,  and from computer models.  The following must
be accomplished:

     1.   A determination of the most useful integrating
          variables for forest ecosystems that indicate the
          effects of climatic change;

     2.   Effective sampling designs developed for experiments
          and long-term monitoring at the forest ecosystem scale;
          and

     3.   Improved models capable of projecting regional effects
          on forests across multiple spatial and temporal scales.

                              11-35

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                                                          Forests
Management

     What options are available to the public and private forest
managers and owners in the United States to deal with the changes
in the nation's forests that might occur in the next century?
Research is needed to accomplish the following:

     1.   Understand the socioeconomic impacts of all forest
          ecosystem effects to clarify economic risks and
          alternatives; and

     2.   Develop technology to mitigate the adverse effects or
          to exploit the benefits of forest change, such as
          breeding, bioengineering, transplanting, fertilization,
          irrigation, and other management approaches.

Timing

     The timing of the research is critical.  The effects of
climatic change may -be some decades away, but this should not
lessen the urgency to begin research toward better information
and methods.  The complexities of the science are very large.  To
build the required base of knowledge to deal with potential
forest changes before they are upon the nation will require
significant time and resources.
                                                                     i
                              11-36

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Chapter 11
REFERENCES

Barbour, M.G., J.H. Burk, and W.D. Pitts.  1987.  Terrestrial
Plant Ecology, 2nd ed.  Menlo Park, CA:  Benjamin/Cummings
Publishers.

Botkin, D.B.  1979.  A grandfather clock down the staircase:
stability and disturbance in natural ecosystems.  In: Waring,
R.H.,  ed.  Proceedings of the 40th Annual Biological Colloquium.
Forests: Fresh Perspectives From Ecosystem Analysis.  Corvallis,
OR:  Oregon State University Press, pp. 1-10.

Clawson, M.  1975.  Forests for Whom and for What?  Resources  for
the Future.  Baltimore, MD:  Johns Hopkins University Press.

Cubbage, F.W., D.G. Hodges, and J.L. Regens.  1987.  Economic
implications of climate change impacts on forestry in the South.
In:  Meo,  M., ed.  Proceedings of the Symposium on Climate
Change in the Southern U.S.:  Future Impacts and Present Policy
Issues.  New Orleans, LA:  U.S. Environmental Protection Agency.

Fosberg, M.A.  1988.  Forest productivity and health in a
changing atmospheric environment.  In: Berger, A., ed.  NATO
Symposium on Climate and Geosciences.  Dordrecht, The
Netherlands:  Reidel Publishing Company.  In press.

Hammond, A.L.  1972.  Ecosystem analysis: biome approach to
environmental science.  Science 175:46-48.

Hedden, R.  1987.  Impact of climate change on forest insect
pests in the southern U.S.  In:  Meo, M., ed.  Proceedings of  the
Symposium on Climate Change in the Southern U.S.:  Future Impacts
and Present Policy Issues.  New Orleans, LA:  U.S. Environmental
Protection Agency.

Ince, P.J.  1987.  Technology, timber demand and timberland
investment.  In:  A Clear Look at Timberland Investment,
Milwaukee, WI, April 27-29, 1987.  Conference proceedings.
Forest Products Research Society.

Lavdas, L.G.  1987.  The impact of climate change on forest
productivity.  In:  Meo, M., ed.  Proceedings of the Symposium on
Climate Change in the Southern U.S.:  Future Impacts and Present
Policy Issues.  New Orleans, LA:  U.S. Environmental Protection
Agency.
                              11-37

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                                                          Forests
Leverenz, J.W., and D.J. Lev.  1987.  Effects of carbon dioxide-
induced climate changes on the natural ranges of six major
commercial tree species in the western United States.  In:
Shands, W.E., and J.S. Hoffman, eds.  The Greenhouse Effect,
Climate Change, and U.S. Forests.  Washington, DC:  Conservation
Foundation, pp. 123-156.

Manion, P.O.  1981.  Tree Disease Concepts.  New Jersey:
Prentice Hall.

Meo, M., ed.  1987.  Proceedings of the Symposium on Climate
Change in the Southern United States: Future Impacts and Present
Policy Issues.  May 28-29, 1987.  New Orleans, LA: University of
Oklahoma and U.S. Environmental Protection Agency.

Miller, F.W., P.M. Dougherty, and G.L. Switzer.  1987.  Effect of
rising carbon dioxide and potential climate change on loblolly
pine distribution, growth, survival and productivity.  In:
Shands, W.E., and J.S. Hoffman, eds.  The Greenhouse Effect,
Climate Change, and U.S. Forests.  Washington, DC:  Conservation
Foundation,  pp. 157-188.

Pickett, S.T.A., and P.S. White.  1985.  The Ecology of Natural
Disturbance and Patch Dynamics.  Academic Press, Inc.  Harcourt
Brace Jovanovich.

Schallau, C.H.  1988.  The forest products industry and community
stability:  the evolution of the issue.  Montana Business
Quarterly  Summer: 1-8.

Shands, W.E., and J.S. Hoffman.  1987.  The Greenhouse Effect,
Climate Change, and U.S. Forests.  Washington DC:  Conservation
Foundation.

Simand, A.J. and W.A. Main.  1987.  Global climate change:  the
potential for changes in wildland fire activity in the Southeast.
In:  Meo, M., ed.  Proceedings of the Symposium on Climate Change
in the Southern U.S.:  Future Impacts and Present Policy Issues.
New Orleans, LA:  U.S. Environmental Protection Agency.

Solomon, A.M., and D.C. West.  1985.  Potential responses of
forests to C02 induced climate change.   In:   White,  M.R.,  ed.
Characterization of Information Requirements for Studies of C02
Effects:  Water Resources, Agriculture, Fisheries, Forests and
Human Health.  Washington, DC:  U.S. Department of Energy.
DOE/ER-0236.  pp. 145-1709.
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Chapter 11
Solomon, A.M., and D.C. West.  1986.  Atmospheric carbon dioxide
change:  agent of future forest growth or decline?  In:  Titus
J.G., ed.  Effects of Changes in Stratospheric Ozone and Global
Climate, Vol. 3:  Climate Change.
Environmental Protection Agency.
                    Washington, DC:  U.S.
Spurr, S.H., and B.V. Barnes.
New York:  J. Wiley & Sons.
                1980.  Forest Ecology, 3rd Ed.
Strain, B.R., and J.D. Cure, eds.  1985.
Increasing Carbon Dioxide on Vegetation.
Department of Energy.   DOE/ER-0238.
                           Direct Effect of
                           Washington, DC:  U.S
Tirpak, D.A., ed.  1987.  Potential Effects of Future Climate
Changes on Forest and Vegetation, Agriculture, Water Resources
and Human Health, Vol. V.  Assessing the Risks of Trace Gases
That Can Modify the Stratosphere.  Washington, DC:  U.S.
Environmental Protection Agency.  EPA 400/1 - 87/001E.

Titus, J.G.,  ed.  1986.  Climate Change, Vol. 3.  Effects of
Changes in Stratospheric Ozone and Global Climate.  Washington,
DC:  U.N. Environmental Program and U.S. Environmental Protection
Agency.
USDA.  1981.  U.S. Department of Agriculture, Forest Service.
Assessment of the Forest and Range Land Situation in the U.S.
Forest Resource Report No. 22.
                                                An
USDA.  1982.  U.S. Department of Agriculture, Forest Service.  An
Analysis of the Timber situation in the U.S. 1952-2030.  Forest
Resource Report No. 23.

White, M.R., ed.  1985.  Characterization of Information Require-
ments for Studies of C02  Effects:   Water Resources,  Agriculture,
Fisheries, Forests and Human Health.  Washington, DC:  U.S.
Department of Energy.  DOE/ER-0236.
Worrell, A.C.
McGraw-Hill.
1970.   Principles of Forest Policy.   New York:
Young, R.A., ed.  1982.  Introduction to Forest Science.  New
York:  J. Wiley & Sons.
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                            CHAPTER 12

                       BIOLOGICAL DIVERSITY

FINDINGS

Unlike most other impacts, a loss of species and reduced
biological diversity is irreversible.  The ability of a natural
community to adapt to changing climatic conditions will depend on
the rate of climate change, the size of species ranges, the
dispersal rates of the individual species, and whether or not
barriers to species migration are present.  Under rapid climate
change, many species would be lost.

Species Diversity

o    The effect of climate change on species and ecosystems will
     vary, with some species benefiting and others facing
     extinction.  The uncertainties surrounding the rate of
     warming, individual species response, and interspecies
     dynamics, make impacts difficult to assess.   However,
     climate change will alter competitive outcomes and
     destabilize natural ecosystems in unpredictable ways.

o    In many cases, the indirect effects of climate change on a
     population, such as changes in habitat, in food
     availability, and in predator/prey relationships may have a
     greater impact than the direct physiological effects of
     climate change.

o    Natural and manmade barriers to species migration, including
     roads, cities, mountains, bodies of water, agricultural
     land, unsuitable soil types, and habitat fragmentation, may
     exacerbate loss of species.

o    The areas within the United States that appear to be most
     sensitive to changes in climate are those that have a number
     of threatened and endangered species, species sensitive to
     heat or drought stress, and species inhabiting coastal
     areas.
Marine
     The loss of coastal wetlands and coastal habitat resulting
     from sea-level rise and saltwater intrusion may profoundly
     affect the populations of all inhabitants of these
     ecosystems, including mollusks,  shellfish, finfish, and
     waterfowl.  However, there is no evidence to indicate these
     species would become extinct.
                               12-1

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                                             Biological Diversity
Freshwater

o    Freshwater fish in large bodies of water,  such as the Great
     Lakes, may increase in productivity,  but some significant
     species could decline.  Fish in smaller bodies of water may
     be more constrained in their ability to respond to climate
     change.  They also may be adversely affected by reductions
     in water quality.

Migratory Birds

o    Migratory birds are likely to experience mixed effects from
     climate change, with some arctic nesting herbivores
     benefiting and continental nesters and shorebirds suffering.
     The loss of wintering grounds due to sea level rise and
     changing climate could harm many species,  as would the loss
     of inland prairie potholes due to potentially increased
     continental dryness.

Policy Implications

o    Existing refuges, sited to protect a species or ecosystem
     under current climate, may not be properly located for this
     purpose under future conditions, or as species migrate.

o    Wildlife agencies such as the Department of Interior, state
     government agencies and conservation organizations may wish
     to assess the feasibility of establishing migratory
     corridors to facilitate species migration.

o    Areas that will become suitable future habitat for
     threatened and endangered species need to be identified and
     protected, such as lowland areas adjacent to current
     wetlands.

o    The practice of restoration ecology will need to be
     broadened to restore ecosystems in new areas as climates
     shift.

o    The increase in the number of species at risk as a result of
     climate change may require new strategies.  Agencies such as
     the Fish and Wildlife Service's Endangered Species Program
     may wish to assess the relative risk of climate change and
     more current stresses on ecological systems.
                               12-2

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Chapter 12
o    The museums and systematic collections of biological
     material in the United States may need to be mobilized to
     provide a comprehensive ability to describe the existing
     species of plants and animals and their ranges.


VALUE OF BIOLOGICAL DIVERSITY

     Maintaining the biological diversity of our natural
resources is an important goal for the nation.  The preamble to
the Endangered Species Act of 1973 formalizes this belief,
stating that endangered and threatened species of fish, wildlife
and plants "are of aesthetic, ecological, educational,
historical, recreational and scientific value to the Nation and
its people."  We depend upon these biological resources for food,
medicine, energy, shelter, and other important products.  Reduced
biological diversity could have serious implications for man, as
untapped resources for research in agriculture, medicine, and
industry are irretrievable lost.

The National Resource

     Public and private lands in the United States provide
sanctuary for an abundant diversity of plants and animals.  About
650 species of birds reside in or pass through the United States
annually.  Over 400 species of mammals, 460 reptiles, 660
freshwater fishes, and tens of thousands of invertebrates can be
found in this country, in addition to some 22,000 plants  (U.S.
Fish and Wildlife Service, 1981).  These species compose a wide •
variety of ecosystem types within the United States, including
coniferous and broad-leaf forest, grassland, desert, freshwater,
marine, estuarine, inland wetland, and agricultural.  Figure 12-1
shows the major ranges of natural vegetation in the United
States.

     The U.S. National parks, forests,  wilderness areas, and fish
and wildlife refuges are among the public lands that provide
sanctuary for wildlife resources, including many endangered
species.  U.S. public lands, which encompass over 700 million
acres (about 32% of the land area of the United States), support
about 700 rare species and communities (Roush, 1986). Over 45% of
the lands held by the Forest Service, Fish and Wildlife Service,
NationalPark Service, and Bureau of Land Management are in
Alaska, and over 48% are located in the 11 most western States
(U.S. Department of the Interior, 1987).   However, much of the
nation's biological diversity lies outside these areas.
                               12-3

-------
£SK
:*_•«•;

WAJf

Illl
Ne
Illl

'Oh"

NSV

^J

•
;!rn
Spruca-tlr forest

Tranaitlon pine-aspen forest

Northeast hardwood forest

Oak-hickory foreat

Oak-pine forest

Southeast pine foreat

Pacific coast toreat
north: spruce, hemlock
south: douglaa fir
Coast Range-Rocky
Mountain conifer forest
X \ '
sw-

•Sg.

.'Jo;

j£l

Mg

c

• Rb
• > <•
rll
Southwest broadleaf woodland

Short grassland

Tall grassland

Sagebrush shrubland

Mesqulte and desert grassland

Creosote bush shrubland

Rlverbottom cypress-tupelo-sweetgum
Mangrove swampland
                       higher spruce-fir
                       summits1 alpine meadow
Figure 12-1.    Natural  vegetation in the United  States,

Source:   Hunt,  1972.


                                  12-4

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Chapter 12
     Private land holdings also account for a great deal of this
nation's biological endowment.  Private groups, such as the
Nature Conservancy and the Audubon Society, manage 500,000 acres
and 86,000 acres, respectively, for biological diversity.


GENERAL COMPONENTS OF BIOLOGICAL DIVERSITY

     Biological diversity can be broadly defined as the full
range of variety and variability within and among living
organisms.  It includes species diversity, genetic diversity, and
ecosystem or community diversity.

Species Diversity

     Each species occurs in a characteristic range or
geographical area.  The factors controlling species ranges
are critical constraints on biological diversity.  The presence
of a species in an area suggests that the species must have
successfully achieved the following:  (1) dispersed into an area
(no barriers to dispersal such as bodies of water or unsuitable
soil types were present); (2) survived in that area (the physical
characteristics of the area were suited to the animal's
physiology, and food was available); and (3) became established
in the area (the organism found an appropriate place in the food
web in the absence of excessive competition and predation, and
was able to reproduce).

     The stresses brought about by development, overuse, and
alteration of habitat have fragmented much of the world's natural
habitat and have created many new barriers; consequently, for
many species,  dispersal has become much more difficult than it
was in the past.  For other species, man has inadvertently aided
dispersal and has caused rapid spread in recent years.  Such
practices as clearcut logging prevent the dispersal of species
adapted to dense forest conditions (e.g., flying squirrels) and
promote the dispersal of species suited to open areas (e.g.,
deer).

     Currently, 495 species are listed as endangered within the
United States,  and over 2,500 species await consideration for
that status by the Fish and Wildlife Service.  The list of
endangered species is dominated by plants,  birds, fishes, and
mammals but also includes insects, amphibians, reptiles,
mollusks,  and crustaceans (U.S. Fish and Wildlife Service, 1988).

     New species are created through the evolutionary process of
speciation and are lost through extinction.  Speciation generally

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                                             Biological Diversity
requires a period of time considerably greater than centuries.
However, extinction as a result of human activities is occurring
extremely rapidly and at an increasing rate.  Owing to its
slowness, the process of speciation does little to offset species
loss to extinction.

     It is difficult to determine the exact rate of species
extinction because the number of species on the Earth is known
only to an order of magnitude.  A recent estimate by Wilson
(1988) places the total number of species between 5 and 30
million.  Assuming 10 million species, Wilson made the rough
calculation that one in every 1,000 species is lost each year.
Wilson then compared this to estimates of extinction rates over
geologic time, which ranged between 1 in every 1 million and 1 in
every 10 million per year.

     Species diversity is fundamental to an ecosystem's function
and integrity.  The significance of rare species should not be
underestimated.  A narrowly or sparsely distributed species may
be a keystone in an ecosystem, controlling the structure and
functioning of the community, or it may be a species of great and
yet unknown value to humans.

Genetic Diversity

     Each species that persists has a characteristic genetic
diversity.  That is, the individuals of that species have among
them a collection of genes and gene combinations that may be more
or less diverse.

     The pool of genetic diversity within a species constitutes
an adaptation to its present environment as well as a store of
adaptive options for a new or changed environment.  The loss of
genetic diversity can contribute to the extinction of a species
by reducing its ability to adapt to changing environmental
conditions.

     Generally, species with larger populations have greater
genetic diversity.  Species that are divided into partly
connected subpopulations also tend to have greater genetic
diversity.  Species near extinction represented by few
individuals in few populations have lower genetic diversity, a
situation exacerbated by inbreeding.
                               12-6

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Chapter 12
Community and Ecosystem Diversity

     Overall species diversity is also a function of the number
of different types of areas in which communities can be built.*
Ecosystem diversity refers to the distinctive assemblages of
species and biotic processes that occur in different physical
settings around the world.


FACTORS AFFECTING THE RESPONSE OF BIOLOGICAL DIVERSITY TO CLIMATE
CHANGE

     Natural communities are a significant indicator of climate
change.  Historically, biological communities have responded to
changes in climate through large-scale geographic shifts, changes
in species composition, physiological adaptation, and extinction
(Peters and Darling, 1985).  Local climate appears to be the
primary factor defining an environmental setting and determining
the species composition and spatial patterns of communities in
terrestrial zones (Bolin, 1986).   Temperature means, temperature
extremes, and precipitation are the factors most often affecting
the natural distributional limits of a species (Ford, 1982),
while the actual distribution of a species is also affected by
soil type, soil moisture, ecological dynamics, and regional
isolation.

Rate of Climate Change

     Predicting how a species or ecosystem might respond to a
given environmental change is difficult.  Adaptation to climate
change will inextricably depend on the rate of climate change.
For some species, migration rates may be inadequate to keep up.

     The infinite number of combinations of dispersal range and
reproductive age make the potential rate of migration different
for every species.  Paleorecords suggest migration rates between
10 and 20 km per century for chestnut, maple, and balsam fir,  and
between 30 and 40 km per century for some oak and pine species
(see Forestry chapter in this report).  On the other hand,  cattle
egrets have shown a much quicker migration rate by colonizing all
of the North American tropics within approximately 40 years.

     As species shift at different rates in response to climate
change, communities may disassociate into new arrangements of
     *The new discipline of landscape ecology attempts to relate
 topographic diversity to community and species diversity.

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                                             Biological Diversity
species.  Local extinction can result either directly from
physiological pressures or indirectly from changes in
interspecies dynamics.  Hence, the affect of climate change on an
area will be to cause sorting and separation of species owing to
the differential rate of migration and species retreat (Ford,
1982).  Ecosystems, therefore, will not migrate as a unit.

     The rate of climate change will be crucial to the survival
of the species.  A 3°C increase in temperature, for example,
would effect a several hundred kilometer poleward shift in the
temperate vegetation belts (Frye, 1983).   If this change took
place within a century, species would need to migrate several
kilometers each year to adapt to this warming.  Plants have a
wide range of migration rates, and only some may be able to
achieve this rate.

     Many factors make evaluating the impact of climate change on
ecosystems difficult.  The great interdependencies among species
in an ecosystem add considerable uncertainty to the effect that
the various responses of individual species will have on the
system.  An impact upon a single species could significantly
change the entire ecosystem.   For example, elimination of a tree
species in a region could have a significant effect on the whole
forest ecosystem including birds, insects, and mammals.

     Animal populations are generally much more mobile than
plants.  But animal distributions heavily depend on vegetation
for food, protection, and nesting habitat.  Species not directly
dependent on vegetation ultimately depend on some other species
that is.  The ranges of the fig wasp and the fig depend entirely
upon one another.  In this case, the plant species depends on a
single pollinator, and the insect species relies upon a.single
species of plant for food (Kiester et al., 1984).

     Species do not immediately respond to changed and changing
environmental conditions.  A negative response, such as local
extinction in an area, is usually quicker than the positive
response of new species' colonization of a region (see Forestry
chapter of this report).  In the Arctic,  the lag period between
climate change and species response (colonization) may be several
hundred years (Edlund, 1986).   This lag period will leave areas
open for weedy, opportunistic species that can quickly migrate
and propagate in a region.

Barriers to Response

     How quickly species migrate is affected by natural and
manmade barriers and by competition.  Peters and Darling (1985)

                               12-8

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Chapter 12
examined potential species' responses to climate change,
ecological interactions, and barriers to adaptation.  Physical
barriers include mountains, bodies of water, roads, cities,
agricultural land, inappropriate soil type, and habitat
heterogeneity  (landscape patchiness).

Reserve and Island Species

     Species living on reserves have additional constraints on
their ability to respond to climate change that are similar to
those of island species.  This problem has become known as the
island dilemma.  Species on reserves are often remnants of larger
populations and are more susceptible to environmental stress.
Additionally, reserves that originally may have been well sited
to protect a vulnerable population and its habitat may, after
climate change and population response, exist outside the now
suitable range.  Figure 12-2 illustrates this problem.

     Species on reserves are likely to be pressured from two
directions as a result of climate change.  A population isolated
on a reserve surrounded by altered or unsuitable habitat receives
little immigration from populations outside the reserve.  Also,
that population may not be able to colonize areas outside the
reserve as these areas become suitable because of development or
other alterations of habitat.  Large reserves and buffer zones
around reserves help to lessen this problem.  Corridors between
reserves lessen the problem of spatial isolation by allowing for
some migration between reserves.

     Habitat Area

     Even without the added pressure of climate change, reserve
populations are stressed because many reserves are not large
enough to support a self-sustaining population (Lovejoy, 1979).
The predictive theory of island biogeography (MacArthur and
Wilson, 1967) showed that, other factors being equal, large
islands accommodate larger numbers of land-dwelling species than
do small islands.  This held true for other ecologically isolated
islands, such as mountaintops,  woodlots, and lakes.  Also, when
large ecosystems become smaller through fragmentation, the number
of species always declines.  Figure 12-3 shows how mammalian
extinctions have been inversely related to refuge area in North
American parks.

Mountain Species

     Just as species can migrate latitudinally,  they can respond
altitudinally to climate change by moving up a mountain slope.

                               12-9

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                a.
                b.
                c.
                      SL
                      SL
                   New SL
                        '  /FORMER\ \
                        v \ RESERVE '  \
                         %  X       /   »
                      7
                   Old SL
                                                t
                                                N
Figure 12-2.
Effect of climate chante on biological reserves
Hatching indicates the following:   (a) species
distribution before human habitation   (SL
indicates southern limit of species range);  (b)
fragmented species distribution after human
habitation; (c) species distribution after
warming.
Source:  Peters and Darling  (1985).
                              12-10

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QC
o
o
_J
c/1
  50H
  40-
  30-
  20-
  10-
   0-1
      4  6
                                                                        10
    100     2100    4100    6100     8100    10100   12100

                               REFUGE AREA (Km SQ)
                               14100
16100
18100
20100
                  PARK
    1)    Bryce Canyon
    2)    Lassen Volcano
    3)    Zion
    4)    Crater Lake
    5)    Mount Rainier
    6)    Rocky Mountain
    7)    Yosemite
    8)    Sequoia-Kings Canyon
    9)    Glacier-Waterton
    10)   Grand Teton-Yellowstone
                   AREA (km2)

                       144
                       426
                       588
                       641
                       976
                     1,049
                     2,083
                     3,389
                     4,627
                    20,736
PERCENT OF ORIGINAL
   SPECIES LOST

       36
       43
       36
       31
       32
       31
       25
       23
         7
         4
  Figure  12-3.
Habitat  area and loss of  large animal  species in
North American parks  (1986)
  Source:   Newmark  (1987).
                                  12-11

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                                             Biological Diversity
Species can often adapt more easily to changing conditions on a
slope because a shorter migration is required to effect the same
temperature change.

     Among the problems associated with altitudinal migration are
displacement of the species at the top (Peters and Darling,
1985).   Also, with the increase in altitude, the area available
for colonization usually becomes smaller, communities become very
isolated, and these smaller populations are more prone to
extinction.

     Peters and Darling conclude that some of the species and
communities at greatest risk from changing climate include
peripheral populations (located near the edge of a contracting
species range); geographically localized species (reserve and
island species); genetically impoverished species (small
populations); specialized species (living in narrow niches); poor
dispersers; and alpine, arctic, and coastal communities.
CLIMATE EFFECTS RESEARCH

     This section reviews some previous studies of ecological
response to past changes in climate, recent studies of potential
response to anticipated future climate change, and studies funded
by EPA for this report, which use climate change scenarios from
general circulation models for a doubled C02  environment (see
Table 12-1).

     In only the last few years, biological diversity has emerged
as both a major scientific and policy issue.   At present, much
effort is being devoted to. both the scientific and policy aspects
of biological diversity.  This effort should result in much new
information is the relatively near future.

Forest Ecosystems

     The tree species that make up any forest are major factors
in determining the biological diversity found there.
Treesprovide a multitude of habitats and are the basis of much of
the food web in a forest.

     The changes in forest composition resulting from climate
change, (see Forests:  Chapter 11),  will have significant
implications for biological diversity.  Potential northerly range
shifts of several hundred to a thousand kilometers may be limited
by the tree species' ability to disperse.  One possibility is
that southern pine forests will move farther north into the

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Chapter 12
         Table 12-1.  Studies Conducted for This Report
                      Cited in this Chapter
          Potential Responses of Great Lakes Fishes and Their
          Habitat to Global Climate Warming — Magnuson, Regier,
          Shuter, Hill, Holmer and Meisner, University of
          Wisconsin

          The Effects of Global Climate Change on the Water
          Quality of Mountain Lakes and Streams — Byron, Jassby
          and Goldman, University fo California at Davis

          The Effects of Climate Warming on Lake Erie Water
          Quality — Blumberg and DiToro, HydroQual, Inc.

          Ecological Effect of Global Climate Change:  Wetland
          Resources of San Francisco Bay — Josselyn and
          Callaway, San Francisco State University

          Projected Changes in Estuarine Conditions Based on
          Models of Long-Term Atmospheric Alteration —
          Livingston, Florida State University
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                                             Biological Diversity
regions currently occupied by mixed hardwood species.  Some of
these hardwood forests contain the highest tree species
diversityfound anywhere in the United States (Braun, 1950).  As
they migrate north, species would inevitably be lost, and overall
biological diversity would substantially decrease.

     As forests are disrupted, the land will be invaded by weedy,
opportunistic species, creating a system with very low diversity
similar to that following logging. Ultimately these systems will
not persist as succession takes place, but the pattern of
succession following the removal of a forest by rapid climate
change is unknown.

Tropical Forest Ecosystems

     The greatest concentration of biological diversity in the
world is in the rain forests of the Tropics (Wilson, 1988).
Besides reducing diversity, deforestation contributes to
disrupting the global carbon cycle by releasing CO2 into  the
atmosphere and will directly affect the rate of climate change
(Prance, 1986).  Indeed, on a global scale the problems of
tropical deforestation, rapid climate change through (among other
factors) increased C02 production,  and the loss  of biological
diversity can be seen as aspects of the same problem.

     Tropical forests are also important as wintering grounds for
migratory birds coming from the United States and as sources of
new knowledge, because the patterns of interactions between
species and climate are at their most sensitive and complex
there.  The Tropics may provide important leading indicators of
climate change (Robinson, 1978; Janzen, 1986).


Freshwater Ecosystems

     A study conducted by Magnuson et al. concludes that in most
areas of the Great Lakes, climate warming would increase the
amount of optimal thermal habitat for warm-, cool-, and cold-
water fishes  (see Chapter 5, Great Lakes); although overall
productivity would increase, overall biological diversity could
decrease through intensified species interactions.

     A study by Byron et al. on mountain lakes suggests that
climate change would cause a range of impacts, including higher
productivity, changes in species composition,  and decreased water
quality resulting from an increase in algal growth (see Chapter
4, California).  Blumberg (see Chapter 5, Great Lakes)  found that
thermal stratification in Lake Erie could decrease dissolved

                              12-14

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Chapter 12
oxygen levels.  This result, with possible loss of biological
diversity, is likely to be repeated in many lakes.

     The combined pressures of warmer waters, saltwater
intrusion, and a rising sea level will significantly affect
estuaries.  The regional studies suggest that coastal estuaries
are likely to see a growth in marine species and a loss of some
estuarine species.  A study by Josselyn on the San Francisco Bay
estuary suggests a decline in species that use the delta for
spawning  (see Chapter 4, California).  Livingston concluded that
crabs, shrimp, oysters, and flounder in the Apalachicola estuary
could not survive the warming projected by the GISS and GFDL
scenarios (see Chapter 6, Southeast).

Saltwater Ecosystems

     In general, a warmer global climate is expected to increase
productivity in ocean fisheries, but the location and relative
abundance of species are likely to change (Sibley and Strickland,
1985).  Up to some threshold temperatures, such as 2°C, warmer
ocean temperatures are likely to increase ocean productivity, but
beyond that threshold, productivity could decline (Giantz, 1988).
It is likely that as productivity decreases, biological diversity
would decrease as well.

Coral Reef Ecosystems

     Coral reefs provide the structural base for the very
biologically diverse reef ecosystems.  Coral reefs in the
Caribbean and the Pacific may be severely stressed as a result of
warmer water temperatures and the rising sea level associated
with climate change.  Extensive bleaching of coral (the expelling
of symbiotic brown algae in response to environmental stress)
occurred in the Pacific after the 1982-83 El Nino (Glynn, 1984)
and in the Caribbean following a summer of elevated water
temperatures in 1987 (Roberts, 1987).  Loss of the brown algae,
the primary food source of the coral, is thought to kill coral,
making the reef ecosystem vulnerable to erosion and physical
devastation.

     Coral reefs also will be affected by sea level rise.
Studies by Buddemeier and Smith (1987)  and Cubit (1985) suggest
that vertical accretion of reef flats eventually may be unable to
keep up with an accelerating rise in sea level.   Reef flats also
may be subject to the stress of increasingly large waves,
erosion,  and sedimentation,  which can inhibit coral growth
(Buddemeier, 1988).
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                                             Biological Diversity
Arctic Ecosystems

     Within the North American arctic, plant size, vigor, and
reproduction could be expected to increase with higher
temperatures.  Some low-lying plants would most likely become
upright, and there would be a northerly movement of the tree line
and all vegetative zones (Edlund, 1986).

     However, in the Arctic, rising temperatures may be a mixed
blessing. Overall biological productivity is likely to increase,
and some species may be able to increase their range. But many
species specially adapted to the Arctic will face the same type
of problem that mountaintop species face:  they will have nowhere
to go once they reach the Arctic Ocean.  Thus, native Arctic
species may be specially at risk.  Other Arctic species may face
their own problems. For example, caribou will be severely harmed
if rivers do not freeze for long enough periods to allow for
migration.

Migratory Birds

     Migratory waterfowl are likely to experience very mixed
effects as a result of warmer temperatures (Boyd, 1988) .
Herbivorous, Arctic nesting species, such as geese, are likely to
benefit from the shortened winter season and from the increases
in vegetation, in nesting habitat, and in ecosystem productivity
(Harington, 1987).  Smaller Arctic nesting shorebirds, on the
other hand, are likely to be harmed by the encroachment of taller
vegetation, potentially eliminating the preferred low-lying
tundra breeding ground.  Other effects on shorebirds could result
from changes in ecosystem predator/competitor relationships and
changes in the seasonal timing of such events as larval blooms,
upon which these birds depend for nourishment while in a
flightless stage and during migration  (Myers, 1988).

     Waterfowl that breed in the continental interior may suffer
more than arctic nesters.  Over half of all waterfowl in North
America originate in the prairie pothole region, a large
agricultural area riddled with highly ecologically productive
permanent and semipermanent wetlands.  Increased temperature and
changes in seasonal precipitation could reduce the highly
variable number of potholes (wetlands) in the area and could
significantly impair the productivity of breeding ducks (Burke,
1988) .  Over 35% of the seasonal wetlands within the prairie
pothole region were dry during the breeding season owing to the
drought of 1988 (U.S. Fish and Wildlife Service, 1988).  The Fish
and Wildlife Service is forecasting that only 66 million ducks
will migrate during the fall of 1988, a total of 8 million fewer

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Chapter 12
than in 1987 and the second-lowest on record  (Irion, 1988).  The
productivity index for mallards  (number of young per adult) is
0.8, which is down by over 20% from the historical average  (U.S.
Fish and Wildlife Service, 1988).

     Waterfowl and other migratory birds are  likely to be
affected  on both ends of their migratory journey and at staging
areas along the way.  The loss of coastal wetlands, already an
area of great concern in the United States, reduces the amount of
habitat available to waterfowl, creating population pressures on
a limited resource.  Of the 215 million acres of wetlands in the
coterminous United States at the time of settlement, fewer than
99 million acres (46%) remain  (U.S. Fish and Wildlife Service,
1987).  Loss of an additional 26-82% of existing coastal wetlands
is expected over the next century as a result of a 1-meter rise
in sea level, saltwater intrusion, and human development (see Sea
Level Rise:  Chapter 9).  Loss of wintering habitat along the
Gulf of Mexico would affect many waterfowl, including mallards,
pintails, and snow geese.

     The Tropics, which may be significantly altered by rapid
climate change, is the winter home for many species of migratory
birds.  The need to protect a species in all parts of its range
underscores the truly global nature of the effects of rapid
climate change on biological diversity (Terborgh, 1974) .

Endangered Species

     Hundreds of species are currently listed-as endangered in
the United States,  and several thousand await consideration for
that status.  These species are likely to be stressed further as
a result of climate change..
     Threatened and endangered species of the Southeast are very
susceptible to the impacts of sea level rise.  Some species
potentially at risk in that region include the Key deer, manatee,
Florida panther, and Everglades kite (Breckenridge, 1988).
Climate change could also greatly increase the number of rare,
threatened, and endangered species in the United States.


Other Direct and Indirect Stresses

     As plant and animal species experience increasing pressures
from changes in temperature,  precipitation, and soil moisture, so
too will agriculture and urban water supplies.  The changes that
result from the human response to climate change may have the
greatest impact on biological diversity.   If the continental
interior of North America dries,  for example, habitats may be

                              12-17

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                                             Biological Diversity
cultivated, and our current uses of water resources may change.
These secondary effects may also prove detrimental to biological
diversity.


NATIONAL POLICY IMPLICATIONS

     Climate change presents new challenges for policymakers,
regulators, and resource managers.  Planning for climate change
may help to minimize the disruption to natural systems and
facilitate adaptation under changing conditions.  Decisions will
need to be made in an environment of increased pressure on many
other resources.

     Policies regarding rare and endangered species are likely to
change as the number of species at risk greatly increases.  As
more species become stressed and potentially threatened by
climate change, reevaluation of protection policies may be
required.  The tradeoffs between protection of individual species
and species' habitat and the broader protection of biodiversity
will have to be reexamined.  As a part of this question,
decisions concerning whether to protect existing communities or
foster the establishment of new ones will need to be made.

Management Options to Maintain Biological Diversity

     Only a limited number of techniques are available for
maintaining biological diversity. However, these techniques can
be adapted and intensified to meet the potentially great impacts
of rapid climate change.

Maintenance of Native Habitats

     The most direct way to maintain biological diversity is to
manage land to retain ecosystems, communities, and habitats.
This has been successfully undertaken on a broad scale by Federal
and State governments and by private organizations.  Ecosystem
conservation, especially as represented by the National Parks and
other large reserves, maintains much of our national biological

diversity.  This will continue to be a useful first step for
maintaining biological diversity in the face of climate change.

     Land acquisition and management policies will need to take
climate change into account.  Climate change and the future
requirements of whole ecosystems must be considered in siting and
managing reserves.  To preserve functioning ecosystems, large
areas of land will be required.  Preserves need to be at least

                              12-18

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Chapter 12
large enough to support self-sustaining populations.  Lands that
will be more important as future plant and animal habitat need to
be identified, evaluated, and set aside.  Although identification
of appropriate future habitat is difficult, and highly dependent
on the future rate and extent of climate change, some areas, such
as lowland areas adjacent to current wetlands, hold good
potential for habitat protection.

     To protect a species, alternative sites should be considered
with regard to the ecological needs of target species under
changing conditions.  Siting preserves in mountainous areas is
beneficial because it allows for the shorter-distance altitudinal
shifts of adjustment to changing climate.  Stream corridors,
which can be effective avenues of dispersal for terrestrial as
well as aquatic organisms, should be protected wherever possible.
Providing corridors for migration between reserves also will
enhance the ability of wildlife to adapt to climate change.
Ideally, these corridors should be wide enough to maintain the
ecosystem characteristics of the reserve in their center.  Some
species do not find the habitat conditions of narrow corridors
suitable for migration.

Maintenance of Species in Artificial Conditions

     When individual species are threatened with extinction, a
possible option is to ensure that the species is propagated in
captivity.  Indeed, some rare species, such as the Pere David
deer and the California condor, now exist only in captivity. This
technique can be made to work for a variety of species, depending
on their biology and the degree to which they successfully adapt
to captive conditions.  As more species become threatened with
extinction due to climate change, the effort applied in this area
may have to increase dramatically.  However, only a tiny fraction
of the nation's species can be maintained in this way.

Restoration of Habitat

     Restoration ecology is a new discipline whose goal is to
develop methods to restore damaged ecological communities to
their prior unaltered state. Except in forestry, where
reforestation has a longer tradition,  restoration ecology has
been in existence for only a few years.  Nonetheless, it offers
some real promise for ameliorating the effects of rapid climate
change.

     Normally,  restoration is done at the site where the
community previously existed and was altered or damaged.
Historical and baseline information is used to manage the species

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                                             Biological Diversity
in such a way as to eliminate unwanted new species and to
encourage and possibly reintroduce native species.

     The next step in restoration ecology is to restore natural
communities on sites where they have not previously existed. This
activity has not yet been attempted but may be necessary to save
communities displaced by climate change. If the climate changes
so that many of the key species of a community can no longer
survive in their original range, and if the species are incapable
of dispersing and establishing themselves elsewhere, then the
artificial transplantation of entire communities may become
necessary.  This transplantation of communities would be a
monumental task and could help to save much biological diversity,
but it cannot possibly be undertaken on the scale necessary to
preserve all species threatened by climate change.  Restoration
ecology can be useful for extending reserve boundaries and
providing migratory corridors.

Planning Options

     While there are only a few management techniques to maintain
biological diversity, many different groups in our society can
implement them.  These groups can be divided into the private and
public sectors.

     Many different groups in the private sector, ranging from
private individuals to large conservation organizations, will
have an interest in maintaining biological diversity.  However,
all will need information about the current and probable future
state of biological diversity.  The Federal Government may be
able to play a role here by providing information on the study of
biological diversity.

     Resource managers and policymakers should incorporate
climate change into their long-term planning.  Periodic reviews
of the management plans for public lands should include
consideration of the possible effect of climate change.

     The four major Federal land management agencies develop
plans intended to lay out a comprehensive framework and direction
for managing Federal land.  Land Resource Management Plans,
required for each National forest, define the direction of
management in the forest for the next 10 to 15 years.  In
addition, the Forest Service prepares 50-year plans, as required
by the Resource Conservation Act.  The National Park Service
prepares a General Management Plan for each unit in the system
that defines a strategy for achieving management objectives
within a 10-year time frame.  A Statement for Management is also

                              12-20

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Chapter 12
prepared for each National park and is evaluated every 2 years;
this includes a determination of information needs.  The Bureau
of Land Management's  (BLM's) Resource Management Plans and the
Fish and Wildlife Service's Refuge Master Plans are prepared and
revised as needed for BLM Resource Areas and Wildlife Refuges
(U.S. Department of the Interior, 1987).

     The Federal Government manages an enormous amount of land
and should consider management options to preserve biological
diversity on much of that land.  The major management techniques
of habitat maintenance and restoration ecology could be applied
by the agencies actively responsible for managing the nation's
public lands.
RESEARCH AND DEVELOPMENT NEEDS

     The ability to protect biological diversity is severely
restricted by a lack of knowledge regarding the rate of climate
change, the precise nature of the change, how individual species
will respond, and how ecological balances will shift.  Increased
research effort is needed in three areas: identification of
biological diversity, species interactions and biological
diversity, and management options for biological diversity.

Identification of Biological Diversity

     The first and most pressing need is for more and better
coordinated research to simply identify the biologically diverse
resources of our country.  This involves both systematics
(organism classification) and ecology. The nation needs a more
coordinated ability to identify its plants and animals (see H.R.
4335),  and it needs range maps and habitat requirement
information for those species.

     The apparently simple task of identifying the species of
plants and animals that exist in a given area is actually a major
barrier to further understanding.  Common species are usually
relatively easy to identify, but even they present serious
problems when attempts are made to decide whether a widespread
group is, for example, one or two species.  The nation's museums
and systematic collections needs to be mobilized to solve this
problem. For example, there is currently no federally sponsored
Flora (listing of all known plants)  of the United States. In this
regard, the United States lags behind many Third World countries,
such as Panama and Peru.
                              12-21

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                                             Biological Diversity
Species Interactions and Biological Diversity

     The second area needing research is the direct effects of
climate on species and the indirect interactions of species with
other species dependent on climate.  Comprehensive mapping of
species ranges along temperature and moisture gradients would
provide valuable information.  The direct effect of climate
change on vegetation needs to be better assessed, and more
estimates of species dispersal rates would significantly improve
our ability to identify species at greatest risk.

     A variety of ecosystems within a diversity of climatic
regions and terrains need to be intensively studied using
analogue climate regions under changed climate conditions.
Although an ecosystem's response under changing climate
conditions will not be wholly predictable, modeling individual
ecosystem responses would enhance knowledge of the likely
effects.  Further research on how species interact and how
trophic structures might change with climate would help
predictive capabilities.

     It will be impossible to study in detail even a fraction of
the nation's species. Those groups chosen for study either must
be representative of many species or must possess some special
properties (such as extreme sensitivity to climate change).   The
method of deciding which group to study is itself a major
outstanding research question.

Management Options for Biological Diversity

     Management options are limited in both number and scope.
Research is needed to increase the scope of the current
management options and to discover new options.

     National parks, forests, and wildlife refuges are suitable
areas for study.  In-depth evaluation of 5 to 10 of these areas
could provide valuable information regarding the range of impacts
and management options.
                              12-22

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Chapter 12
REFERENCES

Bolin, B., B. Doos, J. Jager, and R. Warrick, eds.  1986.  The
Greenhouse Effect, Climatic Change, and Ecosystems  (SCOPE 29).
Chichester:  John Wiley & Sons.

Boyd, H.  1988.  Impact of Climate Change on Arctic-Nesting
Geese.  Paper presented at Climate Institute Wildlife Symposium,
Washington, DC; January 21.

Braun, E.L.  1950.  Deciduous forests of eastern North America.
New York:  Hafner Publishing Company.

Breckenridge, R.  1988.  Personal Communication.   (Phone
conversation).

Brown, L., W. Chandler, A. During, C. Flavin, L. Heise, J.
Jacobson, S. Postel, C. Shea, L. Starke, and E. Wolf.  1988.
State of the World 1988.  WorldWatch Institute.  New York:  W.W.
Norton and Co., Inc.

Buddemeier, R.  1988.  Impacts of Climate Change on Coral Reefs,
Islands and Tropical Coasts.  Paper presented at the Climate
Institute Workshop on the Impact of Climate Change on the Third
World, Washington, DC; March 24-25.

Buddemeier, R., and D. Hopley.  1988.  Turn-Ons and Turn-Offs:
Causes and Mechanisms of the Initiation and Termination of Coral
Reef Growth.  Paper presented for submittal to the Proceedings of
the Sixth International Coral Reef Symposium, James Cook
University, Townsville, Australia; August 8-12.

Buddemeier, R., and S. Smith.  1987.  Coral Reef Growth in an Era
of Rapidly Rising Sea Level:  Predictions and Suggestions for
Long-Term Research.  Coral Reefs, Printer's Proof.

Burke, L.  1988.  The Impact of Climate Change on Mallard
Productivity in the Prairie Pothole Region.  Work in progress.

CEQ.  1980.  Council on Environmental Quality.  Environmental
Quality:  Eleventh Annual Report.  Washington, DC:  U.S.
Government Printing Office.

Cubit, J.  1985.  Possible Effects of Recent Changes in Sea Level
on the Biota of a Caribbean Reef Flat and Predicted Effects of
Rising Sea Levels.  Preprint from the Proceedings of the Fifth
International Coral Reef Congress, Tahiti.
                              12-23

-------
                                             Biological Diversity
Edlund, S.  1986.  Modern Arctic Vegetation Distribution and Its
Congruence With Summer Climate Patterns.  Environment Canada,
Proceedings: Impact of Climatic Change on the Canadian Arctic.

Ford, Michael.  1982.  The Changing Climate.  London: George
Allen and Unwin.

Frye, R.  1983.  Climatic change and fisheries management.
Natural Resources Journal 23:77-96.

Glantz, M.  1988.  Personal Communication.  (Phone conversation).

Glynn, Peter. 1984. Widespread Coral Mortality and the 1982-83 El
Nino Warming Event.  Environmental Conservation 11(2):133-140.

Harington, C.  1987.  The Impact of Changing Climate on Some
Vertebrates in the Canadian Arctic.  Climate Institute,
Proceedings of the First North American Conference on Preparing
for Climate Change.

Irion, R.  1988.  Washington Post, Monday, August 1, 1988.
Drought helps 2 Endangered Species Rebound, but It's a Dismal
Year for Ducks.

Janzen, D. 1986. The future of tropical ecology. Annual Review of
Ecology and Systematics 17:305-324.

Jordan, W., R. Peters, and E. Allen.  1988.  Ecological
restoration as a strategy for conserving biological diversity.
Environmental Management 12(1):55-72.

Kiester, A.R., R. Lande, D.W. Schemske.  1984.  Models of
coevolution and speciation in plants and their pollinators.
American Naturalist 124(2):220-243.

Leatherman, S.  1987.  Effects of Sea Level Rise on Beaches and
Coastal Wetlands.  Climate Institute, Proceedings of the First
North American conference on Climate Change, Washington, DC, pp.
140-146.

Lovejoy, T.  1979.  Refugia, refuges and minimum critical size:
problems in the conservation of the neotropical herpetofauna.
In:  Duellman, W., ed. The South American Herpetofauna: Its
Origin, Evolution and Dispersal.  University of Kansas Museum
Natural Hist. Monograph 7:1-485.

MacArthur, R., and E. Wilson.  1967.  The Theory of Island
Biogeography.  Princeton, NJ:  Princeton University Press.

                              12-24

-------
Chapter 12
Myers, J.P.  1988.  Remarks to Climate Institute Wildlife
Symposium, Washington, DC; January 21.

Myers, N.  1979.  The Sinking Ark.  New York: Pergamon Press.

Naveh, Z., and A. Lieberman.  1984.  Landscape Ecology.  New
York:  Springer-Verlag.

Newmark, W.D.  1987.  A land-bridge island perspective on
mammalian extinctions in western North American parks.  Nature
325:430-432.

Peters, R., and J. Darling.  1985.  The greenhouse effect and
nature reserves.  Bioscience 35(11):707-717.

Prance, G.T.  1986.  Tropical Rain Forests and the World.
Atmosphere.  AAAS Selected Symposium No. 101.  Boulder, CO:
Westview Press, pp. xxi-105.

Regier, H., J. Holmes, J. Meisner.  1987.  Likely Effects of
Climate Change on Fisheries and Wetlands, With Emphasis on the
Great Lakes.  Climate .Institute, Report for the First North
American Conference on Preparing for Climate Change.

Roberts, L.  1987.  Coral bleaching threatens atlantic reefs.
Science 238:1228-9.

Robinson, M.H.  1978.  Is tropical biology real?  Tropical
Ecology 19(1): 	.

Roush, J.  1986.  Private action for public lands.  The Nature
Conservancy News 36(4):4-7.

Sibley, T., and R. Strickland.  1985.  Fisheries:  some
relationships to climate change and marine environmental factors,
In: DOE.  Characterization of Information Requirements for
Studies of CO2 Effects,  Ch.  5.

Strain, B.  1986.  The biosphere and links to climate.  In:
Rosenzweig, C., and R. Dickinson, eds.  Climate-Vegetation
Interactions.  Proceedings of a NASA/Goddard Space Flight Center
Workshop, January 27-29, 1986.  Published by the Office for
Interdisciplinary Earth Studies,  University Corporation for
Atmospheric Research, Boulder CO.

Strain, B.  1987.  Direct effects of increasing atmospheric C02
on plants and ecosystems.  Tree 2(1):18-21.
                              12-25

-------
                                             Biological Diversity
Terborgh, J.  1974.  Preservation of natural diversity:  the
problem of extinction prone species.  BioScience 24(12):7l5-722.

Tiner, R. Jr.  1984.  Wetlands of the United States:   Current
Status and Recent Trends.  U.S. Fish and Wildlife Service.
Newton Corner, Massachusetts:  Habitat Resources.

Toppins, J.C., and J. Bond.  1988.  The Potential Impact of
Climate Change on Fisheries and Wildlife in North America.
Report of the Climate Institute to the U.S. EPA.

U.S. Department of the Interior.  1987.  National Park Service
and National Recreation and Park Association.  Trends 24(2):2-43.

U.S. Fish and Wildlife Service.  1981.  Endangered Means There's
Still Time.  Department of the Interior, U.S. Fish and Wildlife
Service, Washington, DC.

U.S. Fish and Wildlife Service.  1988.  Endangered Species
Technical Bulletin; May.

Wilcox, B.  1982.  Biosphere Reserves and the Preservation of
Biological Diversity.  Towards the Biosphere Reserve:  Exploring
Relationships Between Parks and Adjacent Lands. Parks Canada and
U.S. National Park Service, Kalispell, Montana; June.

Wilson, E.O.  1988.  Biodiversity.  Washington, DC:  National
Academy Press.
                              12-26

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                            CHAPTER 13

            IMPACT OP CLIMATE CHANGE ON AIR QUALITY
FINDINGS
    Changes in regional temperatures, precipitation
    patterns, clouds, windspeed and direction, and
    atmospheric water vapor that will accompany global
    climate change will affect future air pollution levels
    and episodes in the United States.

    While uncertainties remain, it is likely that an
    increase in global temperatures will have the following
    effects on air quality, if other variables remain
    constant.

        Ozone levels in many urban areas would increase because
        higher global temperatures would speed the reaction
        rates among chemical species in the atmosphere.

        Manmade and natural emissions of hydrocarbons and
        manmade emissions of nitrogen and sulfur oxides would
        increase with a temperature rise.  Natural emissions of
        sulfur would also change, but the direction is
        uncertain.  The hydrocarbons and nitrogen oxides
        participate in reactions that produce ozone.

        The formation of acidic materials (such as sulfates)
        would increase with warmer temperatures because sulfur
        and nitrogen oxides would oxidize more rapidly.  The
        ultimate effect on acid deposition is difficult to
        assess because of changes in clouds, winds, and
        precipitation. •

        Visibility may decrease because of the increase in
        hydrocarbon emissions and in the rate at which sulfur
        dioxide is oxidized to sulfate.

    Preliminary analyses of 4°C temperature increase in the
    San Francisco Bay area suggest that maximum ozone
    concentrations would increase by approximately 20%,  that
    the area in which the National Ambient Air Quality
    Standard (NAAQS)  would be exceeded would almost double,
    and that the number of people-hours of exposure would
    triple.   The Midwest and Southeast also would incur high
    concentrations and an increase in the area of high ozone

-------
                          Impact of Climate Change on Air Quality
    by a factor of three.

o   The additional costs for air pollution controls that
    would be caused by global warming cannot be estimated at
    this time.  Increases in ambient ozone levels resulting
    from climate change could increase the number of
    nonattainment areas and make attainment more expensive
    in many regions.  Preliminary estimates suggest that an
    expenditure of several million dollars per year may be
    necessary for additional volatile organic compound (VOC)
    controls.

o   Because of the close relationship between air pollution
    policies and global climate change, it is appropriate for
    EPA to review the impact of global climate change on air
    policies and the impact of air pollution regulations on
    global climate change.


RELATIONSHIP BETWEEN CLIMATE AND AIR QUALITY

    The summer of 1988 provided direct evidence regarding the
importance of weather to pollution episodes in the United States.
Despite significant progress in reducing emissions of many
pollutants over the last decade, the extended stagnation periods
and high temperatures caused ozone levels in 76 cities across the
country to exceed the national standard by at least 25%.   Whether
this recent summer is an appropriate analogue for the future
cannot be determined with certainty, but scientists have
recognized f.or some time that air pollution does vary with
seasons and is directly affected by ventilation, circulation, and
precipitation, all of which could be affected by future.global
climate changes.

Ventilation

    Two major factors, referred to as "ventilation" when
considered together, control the dilution of pollutants by the
atmosphere:  windspeed and the depth of the atmospheric mixing
layer (frequently called the mixing depth).  If windspeed is
high,  more air is available to dilute pollutants,  thus lowering
pollutant concentrations.  The mixing layer (the distance between
the ground and the first upper-layer inversion) tends to trap
pollutants because the inversion on top of it acts as a barrier
to vertical pollutant movement.  Thus,  pollutant concentrations
decrease as mixing depth increases, providing greater dilution.
                               13-2

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Chapter 13
    The ventilation characteristics of an area change, depend on
whether a high- or low-pressure system is present.  Low-pressure
systems usually produce good ventilation because they normally
have greater mixing depths and windspeeds, and precipitation is
often associated with them.  High-pressure systems, on the other
hand, generally produce poor ventilation conditions because they
frequently have smaller mixing depths on their western sides and
lower windspeeds.  They also tend to move more slowly than lows,
so more emissions can enter their circulation patterns. In
addition, they are frequently free of clouds, resulting in
maximum sunlight and therefore more photochemical ozone
production during the day.  Also, during the evenings, the clear
skies allow surface-based  (see below)  inversion layers to form,
concentrating pollutants in a small volume of air and often
creating very high air pollution levels.

    Climatologically, certain places in the country are
frequently windy (Figure 13-1), and others frequently have large
mixing depths (Figure 13-2).  These areas will have cleaner-than-
average air if they do not contain not too many pollutant
sources.  Areas frequently affected by high-pressure systems —
causing lower windspeeds and smaller mixing depths — will have
more major air pollution episodes.

Circulation

    Two semipermanent high-pressure systems are important to the
global circulation pattern and greatly influence U.S.  air
pollution climatology:  the large Pacific high, which is often
situated between the Hawaiian Islands and the west coast of North
America, and the Bermuda high, located over the western Atlantic
Ocean.

    The Pacific high often results in extended periods of air
stagnation over the western United States from Oregon and
California to over the Rockies, and is responsible for many
severe ozone episodes in southern California.  Air stagnation
associated with the westward extension of the Bermuda high occurs
most often during the summer months and affects the eastern
United States from southern Appalachia northward to New England;
it is an important cause of the air stagnation that occurs in the
heavily populated eastern part of the country.  Within the
Bermuda high, pollutants are slowly transported from the
industrial areas of the Ohio River Valley into the populated
areas of the Northeast.   It is also responsible for the general
southwest-to-northeast airflow in the summer, carrying pollutants
along the metropolitan corridor from Richmond to Boston and
exacerbating the ozone problem in the Northeast.

                               13-3

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                             9—9
Figure 13-1.  Mean Annual Windspeed Averaged Through the
              Afternoon Mixing Layer (speeds are in meters per
              second)

Source:  Adapted from Holzworth (1972).
                               13-4

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Figure 13-2.  Mean Annual Afternoon Mixing Height (in hundreds
              of meters)

Source:  Adapted from Holzworth (1972).
                               13-5

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                          Impact of Climate Change on Air Quality
Precipitation

    Atmospheric pollutants in both particulate and gaseous forms
are incorporated into clouds and precipitation.  These pollutants
can then be transported to the ground through rainfall (wet
deposition).   Cloud-formation processes and the consequent type
of precipitation, together with the intensity and duration of
precipitation, are important in determining wet deposition of
pollutants.


PATTERNS AND TRENDS IN AIR QUALITY

    To protect the public health and welfare, the U.S. EPA has
promulgated National Ambient Air Quality Standards (NAAQS).  In
1986, 75 million people lived in counties with measured air
quality levels that violated the primary NAAQS for ozone  (03)
(Figure 13-3) as compared with 41.7 million people living in
countries exceeding the primary NAAQS for total suspended
particulates  (TSP), 41.4 million people for carbon monoxide (CO),
7.5 million people for nitrogen dioxide (NO2) ,  4.5 million people
for lead (Pb), and 0.9 million people for sulfur dioxide  (S02) .

    Although millions of people continue to breathe air that is
in violation of the primary NAAQS, considerable progress is being
made in reducing air pollution levels.  Nationally,  long-term
10-year (1977-86) improvements can be seen for all six of the
above pollutants.

Total Suspended Particulate (TSP)

    Annual average -TSP-levels decreased by 23% between 1977 and
1986, and particulate emissions decreased by 25% for the same
period.  The more recent TSP data (1982-86) show that
concentrations are leveling off, with a 3% decrease in ambient
TSP levels and a 4% decrease in estimated emissions during that
time.  Note that TSP air quality levels generally do not improve
in direct proportion to estimated emission reductions, because
air quality levels are influenced by factors not included in the
emissions estimates, such as natural dust, re-entrained street
dust, and construction activity.  In Figure 13-4, 1986 annual
geometric mean TSP concentrations are plotted for the 89 largest
metropolitan statistical areas (MSAs).  The highest
concentrations generally were found in the industrial Midwest and
arid areas of the West.
                               13-6

-------
       TSP

       S02
        CO
     Ozone
         Pb
             pollutant
]0.9
                7.5
   4.5
                T    i
                   41.7
                   41.4
                                 75
            0   10  20  30 40  50  60 70 80  90

                    mil lions  of persons
Figure 13-3.
Number of Persons Living in Counties With Air
Quality Levels Above the Primary National Ambient
Air Quality Standards in 1986 (based on 1980
population data)
Source:  U.S. EPA (1988).
                           13-7

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Figure 13-4. United States Map of the Highest Annual Geometric
            Mean TSP Concentration by Metropolitan Statistical
            Areas for  1986
Source:  U.S. EPA (1988).
                              13-8

-------
Chapter 13
    In the  future, air quality may decrease as the benefits  of
current pollution control measures are affected by increases in
population  and economic growth.

Sulfur Dioxide (SO2)

    Annual  average S02 levels decreased 37% from 1977 to 1986,
improving at a rate of approximately 4% per year.  An even
greater improvement was observed in the estimated number of
exceedances of the 24-hour standard for SO2 concentration,  which
decreased by 98%.  These decreases correspond to a 21% drop  in
sulfur dioxide emissions during this 10-year period.  However,
most of the exceedances and the improvements occurred at
source-oriented sites, particularly a few smelter sites.

    In Figure 13-5, the 1986 annual arithmetic mean SO2
concentration is plotted for the 89 largest MSAs.  The higher
concentrations were found in the heavily populated Midwest and
Northeast.  All urban areas had ambient air quality
concentrations lower than the current annual primary standard of
0.03 ppm.

Ozone (O3)

    Nationally, between 1977 and 1986, the annual average of the
daily maximum ozone values decreased by 20%; between 1979 and
1986,  03  levels decreased  by 13%.   Emissions of volatile organic
compounds (VOCs), ozone precursors, decreased by 19% from 1977 to
1986,  and by 20% from 1979 to 1986.  The estimated number of
exceedances of the ozone standard decreased by 38% between 1979
and 1986.  In Figure 13-6, the 1986 annual average of the daily
maximum 03 concentrations  is plotted  for  the 89 largest MSAs.
Many of these areas did not meet the 0.12 ppm primary NAAQS.  The
highest concentrations were in southern California,  but high
levels also persisted in the Texas gulf coast, the northeast
corridor, and other heavily populated regions.

Acid Deposition

    Widespread concern exists concerning the effects of acid
deposition on the environment.   With the present monitoring
network density in eastern North America, it is now possible to
quantify regional patterns of concentration and deposition of
sulfate,  nitrate, and hydrogen ions,  primary constituents of acid
deposition.  In Figures 13-7 through 13-9, isopleth maps show the
                               13-9

-------
Figure 13-5.
United States Map of the Highest Annual
Arithmetic Mean SO2 Concentration by Metropolitan
Statistical Areas for 1986
Source:  U.S. EPA (1988)
                              13-10

-------
Figure 13-6.
United States Map of the Highest Second Daily
Maximum 1-hour Average 03 Concentration by
Metropolitan Statistical Areas for 1986
Source:  U.S. EPA (1988).
                              13-11

-------
          1MO
          1M1
           1MJ
                                   SULFATE

                     CONCENTRATION               DEPOSITION
                   ) ( L    .(
                   i -or"-\ \
                                 -^t
                                  >
                     —..^»\
                   u.
                    ~Jl  ^N
Figure 13-7.   Isopleth Maps of Average Annual  Concentrations  (rag

               I"1)  and Total Annual Deposition  (g m"2) of  Sulfate

               in 1980-84


Source:  Seilkop and FinJcelstein  (1987) .


                                13-12

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                                   NITRATE
                    CONCENTRATION
DEPOSITION
          1MO
          1M1
         1M2
Figure 13-8.   Isopleth Maps  of Average Annual Concentration (mg
               I"1) and Total  Annual Deposition  (g  m'2)  of Nitrate
               in 1980-84

Source:  Seilkop  and Finkelsteih  (1987).

                               13-13

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          1M1
                                 HYDROGEN ION

                    CONCENTRATION              DEPOSITION
                               '/H!
                               ft \ ^aJ
                      . v~
                   U*^x\
                                          '--of
                   —J5'
Figure 13-9.   Isopleth Maps of Average Annual  Concentration  (ing
               I"1) and Total Annual  Deposition  (g in'2) of Hydrogen
               Ion in 1980-84

Source:  Seilkop  and  Fihkelstein (1987).

                               13-14

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Chapter 13
geographic pattern of acid deposition, as reflected by the
concentration and deposition of these three species (Seilkop and
Finkelstein, 1987).

    For the relatively short period of 1980 through 1984,
evidence indicates a 15 to 20% decrease in the total deposition
and average concentration of sulfate, nitrate, and hydrogen ions
in precipitation falling over eastern North America.  These
decreases occurred in the regions of maximum deposition and were
most dramatic between 1981 and 1983.  Evidence indicates
increased levels of these species in 1984, although these
concentrations were still less than those observed in 1980 and
1981.  The observed decreases correspond with reported reductions
in the U.S. emissions of sulfur oxides (SOx) and nitrogen oxides
(NOx),  and sulfate and nitrate precursors.  However, the emission
figures are subject to estimation error and should be used
cautiously (Seilkop and Finkelstein, 1987).

STUDIES OF CLIMATE CHANGE AND AIR QUALITY

    Some of the climate factors that could affect air quality
are listed in Table 13-1.  To explain these relationships for
this report, EPA sponsored two projects to identify the potential
impacts of climate change on air quality:

    1.  Climate Change and Its Interactions with Air Chemistry:
        Perspectives and Research Needs - Penner, Connell,
        Wuebbles, and Covey, Lawrence Livermore National
        Laboratory.

    2.  Examination of the Sensitivity of a Regional Oxidant
        Model to Climate Variations - Morris,.Gery, Liu, Moore,
        Daly, and Greenfield - Systems Applications, Inc.

Climate Change and Its Interactions with Air Chemistry

    Penner et al. conducted a literature review of studies on
the relationship of climate and air quality.  They also organized
a workshop on the issue.

Effect of Climate Change on Ozone Formation

    Changes in ventilation, circulation, precipitation, and
other aspects of climate affect the concentrations of the ozone
precursors VOCs and NOx.   Climate changes can also increase or
decrease the rates at which these precursors react to form ozone.
The effects of change in global temperature and in stratospheric
ozone concentration on tropospheric ozone precursor

                              13-15

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                          Impact of Climate Change on Air Quality
Table 13-1.  Climate  Change  Factors  Important  for Regional  Air
             Quality

A CHANGE IN...

 1. the average maximum or minimum temperature and/or
    changes  in their spatial distribution leading to a
    change in reaction rates and the solubility of gases in
    cloud water.

 2. stratospheric 63  leading to a change in reaction rates.

 3. the frequency and pattern of cloud cover leading to a
    change in reaction rates and rates of conversion of SO2
    to acid  deposition.

 4. the frequency and intensity of stagnation episodes or a
    change in the mixing layer leading to more or less
    mixing of polluted air with background air.

 5. in background boundary layer concentrations of water
    vapor, hydrocarbons, NOx, and 03 leading to more or less
    dilution of polluted air in the boundary layer and
    altering the chemical transformation rates.

 6. the vegetative and soil emissions of hydrocarbons and
    NOx that are sensitive to temperature and light levels,
    leading  to changes in their concentrations.

 7. deposition rates to vegetative surfaces whose absorption
    of pollutants is a function of temperature, light
    intensity,  and other factors, .leading to changes in
    concentrations.

 8. energy usage, leading to a change in energy-related
    emissions.

 9. aerosol  formation, leading to changes in reaction rates
    and the  planetary albedo (reflectivity).

10. circulation and precipitation patterns leading to a
    change in the abundance of pollutants deposited locally
    versus exported off the continent.
 Adapted from Penner et al.  (1988).
                              13-16

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Chapter 13
concentrations, reaction rates, and tropospheric ozone
concentrations are discussed below.

    Temperature Change

    Studies  of the Effects  of  Temperature on Ozone.   Smog
chamber and modeling studies have shown that ozone levels
increase as temperature increases.  Kamens et al.  (1982) have
shown in an outdoor smog chamber study that the maximum ozone
concentration increases as  the daily maximum temperature
increases  (holding light intensity constant).  Their  data show
that there is no critical "cut-off" temperature that  eliminates
photochemical ozone production.  Instead, a general gradient is
observed as a function of temperature.

    Temperature-dependent modeling studies were conducted by
Gery et al.  (1987).  Results for New York in June 1980 are shown
in Table 13-2.  In general, ozone concentration increased with
increasing temperature.  The concentration of hydrogen peroxide
(H202) , a strong oxidant that converts S02 to sulfuric acid,  was
also observed to increase with higher temperatures*   This is
compatible with the increase in ozone because the entire
photochemical reaction process is accelerated when temperature
rises.  As a result, cities currently violating the ozone NAAQS
will be in violation to a greater degree in the future, and
cities that are complying with the NAAQS now could be forced out
of compliance just by a temperature increase.  Figure 13-10 shows
the predicted increase in ozone for two temperatures  increases in
Los Angeles, New York, Philadelphia,  and Washington.

    Modeling studies by Penner et al. have shown that the effect
temperature has on ozone formation also depends on the ratio of
volatile organic compounds to nitrogen oxides,  both of which are
ozone precursors.   Figure 13-11 shows that ozone levels will
generally go up,  except in areas where the ratio of VOCs to NOx
is low.

    Temperature change has  a direct effect on ozone
concentrations because it increases the rates of ozone-forming
reactions.   However, temperature rise can also affect ozone
formation by altering four other aspects of climate or the
atmosphere:  cloud cover,  frequency and intensity of  stagnation
periods,  mixing layer thickness, and reactant concentrations.

    Effect of Changes in Cloud Cover.  The reduction  in light
intensity caused by increased cloud cover can reduce ozone
production. Penner et al.  (1988) calculate that a reduction in
                              13-17

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                              Impact of Climate Change on Air Quality
Table 13-2. Maximum Hourly Concentrations and Percentage  Changes for
            Ozone, H202,  and  PAN for the Future  Sensitivity Tests Using an
            EKMA Model for the  Simulation of June  24,  1980,  New York
                                   Ozone


                     Concentration (ppm)

Change in Temp (C)   0	±2	+5

Stratospheric Ozone3
   Base
   -16.6%
   -33.3%
0.125  0.130   0.138
0.150  0.157   0.167
0.165  0.170   0.178
                            0
       Percent change
        (from base)

             +2
       4.0      10.4
20.0   25.6  .   33.6
32.0   36.0  "   42.4
+5
                            Hydrogen Peroxide (H202)
Change in Temp (C)  Concentration (ppb)

Stratospheric Ozone3
   Base
   -16.6%
 •33.3%
0.05   0.06    0.08
0.43   0.58    0.84
3.08   3.31    3.60
                                  Percent change
                                   (from base)
            20.0   60.0
 760.0    1060.01580.0
6060.0    6520.07100.0
                        Peroxyacetyl Nitrate (PAN)
Change in Temp (C)   Concentration (ppb)
                                   Percent change
                                      (from base)
Stratospheric Ozone3

   Base              3.98   3.50    2.79
16.6%                5.85   5.26    4.34
-33.3%               7.59   6.73    5.49
                           	     -12.1 -29.9
                          47.0      32.2   9.1
                          90.7      69.1  37.9
aBase refers to the present stratospheric ozone column.   The -16.6 and
  -33.3% refer to a depletion of the base value.  Ultraviolet  light will
  increase with the depletion.

Source:  Gery et al. (1987).
                                  13-18

-------
  15.0
  14.0
  13.0
  12.0
  11.0
  10.0
I-  9.0
z
01  on
O  O.U

-------
                                                                i
                             HC/HOx=7, INCREASED BL HEIGHT
             10
    15     20    25    30    35
 TEMPERATURE (degrees C)
Figure 13-11.
The effect of temperature on the peak 03
concentrations predicted in a box model
calculation of urban 03 formation.  Calculations
are shown for three hydrocarbon to NOx ratios.
The effect of increasing the boundary layer
depth for the case with a hydrocarbon to NOx
ratio of 7 is also shown
Source:  Penner et al.  (1988).
                            13-20

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Chapter 13
light intensity of 50% throughout the day will reduce the ozone
formation.  However, the magnitude of ozone reduction depends on
the time of day when the cloud cover occurs.  If clouds occur in
the afternoon or evening, little effect is observed in the ozone
production, but if clouds occur during the morning hours,
photochemical reactions are slowed, and less ozone is produced.
Although a global temperature change would affect cloud cover,
the type and direction of the change are unknown.

    The Penner et al. study assumes that cloud cover causes an
equal decrease in all wavelengths of solar radiation.  However,
clouds are not expected to cause an equal decrease at all
wavelengths.   Solar radiation is needed to form ozone.  Since
Penner et al. may have underestimated the intensity of some
wavelengths of light, they may have overestimated the decrease in
ozone production.

     Effect of Water Vapor.  Water vapor is involved in the
formation of free radicals (reactive compounds)  and hydrogen
peroxide, which are necessary for the formation of ozone.  Global
increases in temperature are expected to raise tropospheric water
vapor levels.

    If sources of water vapor are not perturbed by vegetative
changes, and if global circulation patterns do not significantly
affect precipation events (an unlikely assumption),  then global
water vapor levels are expected to increase with increasing
temperature.  A temperature increase of 2° could raise the water
vapor concentration by 10-30% (Penner et al., 1988).  This change
should affect both oxidant formation and sulfur dioxide oxidation
(acid deposition).

    Smog chamber studies have shown that at high pollutant
levels, increases in water vapor can significantly accelerate
both the reaction rates of VOCs and the rate of oxidant formation
(Altshuller and Bufalini, 1971).  In the boundary layer of the
troposphere, Walcek (1985)  has shown with the use of a regional
acid deposition model (RADM)  that the ozone, hydrogen peroxide,
and sulfate production rates all increase with increasing water
vapor.

    Effect of Changes in Frequency and Intensity of Stagnation
Periods.  As noted previously, high-pressure systems
significantly enhance ozone formation potential.   During a high-
pressure episode, pollutants are exposed to high temperatures and
prolonged irradiation (Research Triangle Institute,  1975),
resulting in high levels of ozone.   If the intensity and
                              13-21

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                          Impact of Climate Change on Air Quality
frequency of high-pressure episodes increase with global warming,
then ozone levels can be expected to be even higher.

    Effect of Changes in Mixing Layer Thickness.  As shown in
Figure 13-10, increases the mixing layer height decreases ozone
formation, presumably because there are less ozone precursors per
volume of atmosphere.  An increase of global temperature would
probably lead to a increase in average mixing depths due to
greater convection, which raises the mixing depth and increases
mixing.

    Effect of Changes in Reactant Concentrations.  The
concentrations of ozone precursor pollutants (VOCs,  NOx) play a
large part in determining the amount of ozone produced.  With
increasing temperature,  both natural and anthropogenic emissions
of these precursors are expected to increase, so ozone production
should increase.

    Lamb et al.  (1983) have shown that natural hydrocarbon (VOC)
emissions from deciduous forests would increase by about a factor
of three.-  Emissions of NOx from powerplants would grow due to a
greater demand for electricity during the summer months.
Evaporative emissions of VOCs from vehicles .and refueling would
also be expected to rise with warmer temperatures.  However,
exact predictions of the effects of all these factors on ozone
formation are difficult to make because the relationship between
precursor emissions and ozone is extremely complex and not fully
understood and because increases in emissions are difficult to
quantify.

    An example of this complex relationship between ozone and
its precursors is shown in Figure 13-12.  At high VOC levels and
low NOx, adding or reducing VOCs has very little effect on ozone
formation.  Likewise, when NOx concentrations are high and VOC
concentrations are low,  increasing NOx reduces ozone formation
while lowering NOx increases ozone formation.  Thus, VOCs and NOx
must be examined together when considering any ozone reduction
strategy based on controlling ozone-forming precursors.

    Stratospheric Ozone Change

    Changes in stratospheric ozone concentration can also affect
tropospheric ozone formation because stratospheric ozone
regulates the amount of ultraviolet (UV) radiation available for
producing ozone in the troposphere.  Stratospheric ozone absorbs
UV light from the sun and decreases the UV energy striking the
Earth's surface.  When stratospheric ozone is depleted by the
chlorofluorocarbons (CFCs)  generated by man, more UV reaches the

                              13-22

-------
a.
C-
x
o
    0.28
0.2  0.4  0.6  0.8  1.0   1.2   1.4  1.6   1.8
 J	I
         0.0  0.2  O.4  0.6  0.8   1.0   1.2   1.4   1.6   1.8  2.0

                                 VOC, PPttC
 Figure  13-12.    Ozone  Isopleths as a Function of NOx and
                  Volatile  Organic Compounds (VOCs)
 Source:   Dodge (1977).
                                13-23

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                          Impact of Climate Change on Air Quality
Earth's surface, which increases the photolysis rates of
compounds that absorb solar radiation  (nitrogen dioxide,
formaldehyde, acetaldehyde, ozone, and hydrogen peroxide).*
Faster photolysis produces more free radicals  (high-energy
species) that increase the amount of smog.  Thus, less
stratospheric ozone will lead to enhanced ozone formation in the
troposphere.

    Modeling results for New York from Gery et al.  (1987) show
that tropospheric ozone increased when stratospheric ozone
decreased (Table 13-2).  They also show that H202 and
peroxyacetyl nitrate (PAN) yields increased.   H202 is a  strong
oxidant that converts S02 to  sulfuric acid,  and PAN  is an air
pollutant that damages plants and irritates eyes.

    Effect of Climate Change on Acid Deposition

    Rainwater and surface waters are more acidic than natural
background levels because of industrial and mobile emissions of
S02 and NOx,  which form sulfuric and nitric  acids in the
atmosphere.   In the air, sulfuric acid (H2SO4)  is produced
primarily by the reaction of SO2 with hydroxyl radicals  (high-
energy species); in clouds, the oxidation of S02 to  H2S04 is more
complex, involving reactions with hydrogen peroxide and other
dissolved oxidants.  Nitric acid (HN03)  is produced  in air by the
reaction of hydroxyl radicals with NOx.  The exact pathways for
the formation of these acids are guite complex.

    Organic acids, such as formic and acetic acids, are also
formed in the atmosphere.  However,  their relative importance  to
the acid deposition problem is unknown at present.  Because they
are weak acids (compared to H2S04 an(^ HNO3) ,  their contribution to
the problem is expected to be much less than that of the
inorganic acids (Galloway et al., 1982; Keene  et al., 1983, 1984;
Norton, 1985).

    The acids produced in the atmosphere can be "dry deposited"
to the earth's surface as gases or aerosols, or they can be "wet
deposited" as acid rain.  Changes in total acid levels depend  on
changes both in atmospheric chemistry and changes in
precipitation.   Wet deposition is affected most by the amount,
duration, and location of precipitation.  Since the direction  of
regional precipitation changes is not known, it is not known
whether acid rain will increase or decrease in the future.
     "Photolysis is the breakdown of chemicals as a result of the
absorption of solar radiation.

                              13-24

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Chapter 13
However, many of the same factors that affect' ozone formation
will also affect the total deposition of acids.

    Temperature Change

    Higher temperatures  accelerate the oxidation  rates  of  S02 and
NOx to sulfuric and nitric acids.  Gery et al.  (1987) have shown
that a temperature rise would also speed the formation  of H202,
further increasing the conversion of S02 to sulfuric acid (Table
13-2).  Considering only the chemistry occurring with a 10°C
temperature rise, S02 oxidation increased 2.5 times.   It is
likely that oxidation would also increase with  a smaller
temperature.  The limiting factor in the oxidation of S02 appears
to be the availability of H202.  The model also  suggested that  a
temperature increase would cause more sulfuric  acid to  form near
the sources where SO2 is emitted.

    Effect of Global Circulation Pattern Changes.  Changes in
global circulation patterns will greatly affect local acid
deposition, because they will alter ventilation and precipitation
patterns.  Galloway et al. (1984) have calculated that  over 30%
of the sulfur emissions from the eastern United States  are
transported to the north and farther east.  Changes in
circulation patterns would affect this transport, although the
direction or magnitude of the effect is unknown.

    Effects of Changes in Emissions.  If electricity demand
rises with rising temperatures  (see Chapter 16, Electricity
Demand) and if more fossil fuels are burned, S02 and NOx
emissions would increase.  An approximately 10% growth  in use of
electricity in the summer could increase SO2 emissions  during the
summer by approximately 30%.  This, in turn, would increase acid
deposition.

    Effects of Reduced Stratospheric Ozone.  A  decrease in
stratospheric ozone due to CFCs will increase acid deposition
because more UV radiation will be available to  drive the chemical
reactions.  As discussed above, a modeling study by Gery et al.
(1987) showed an increase in the yield of H2O2 when stratospheric
ozone was reduced by 33%.  Because H202 is a strong oxidant, S02
will probably also be oxidized more quickly into sulfate aerosols
and acid rain, but this depends the availability of liquid water
(e.g., clouds, rain).

    Reduced Visibility.  The growth in natural  organic  emissions
sulfates resulting from warmer temperatures should reduce
visibility.  This assumes that the frequency of rain events,
wind velocity, and dry deposition rates remain  the same. If rain

                              13-25

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                          Impact of Climate Change on Air Quality
events increase, washout/rainout should increase and visibility
would be better than predicted.


MODELING STUDY OF CLIMATE AND AIR QUALITY

Study Design

    Morris et al.  (Volume X) applied a regional transport model
RTM-III to an area covering central California and a region
covering the midwestern and the southeastern United states.  The
model was run for the present-day conditions and for a. future
climate with higher temperatures.  For California, Morris et al.
used input data from August 5-10, 1981; for the Midwest and the
Southeast, they used input data from July 14-21, 1981.

    The RTM-III is a three-dimensional model that represents
point sources embedded in a grid framework.  The model has three
prognostic vertical layers and a diagnostic surface layer.  This
means that the surface layer is represented by actual
observations.  The other three layers are predicted by using the
surface layer data.  The photochemical reactions are based on the
latest parameterized chemical mechanism.

Study Limitations

    The estimates for ozone are only coarse approximations.
Morris et al. used the National Acid Precipitation Assessment
Program (NAPAP)  emissions data of 1980, but appear to
underestimate actual ratios of VOCs to NOx as measured in urban
areas.  Ching et al. (1986) state that for most cities, the NAPAP
data underestimate VOC emission values by a factor of three or
more.

      The model simplified some reactions of the hydrocarbons
(VOCs) because the chemistry is not well  known.  The model
ignored future increases in emissions that would occur with
increased temperatures.

     This study did not estimate climate  induced alterations in
most meteorological variables, except temperature and water
vapor, which is an oversimplification. For example, this study
assumed that the mixing heights remain unchanged for the
temperature increase scenario; in reality, mixing heights could
increase with rising temperature.  Holding the mixing heights
constant probably overemphasized the importance of temperature in
oxidant production, because an increased  mixing layer depth might
have had a dilution effect.

                              13-26

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Chapter 13



Study Results

     Central  California  Study

     Table  13-3  summarizes  the  results  from  the base  case
scenario and a  climate  sensitivity scenario that used a 4°C
temperature increase and an attendant  increase in water vapor
concentration.  All of  the days studied show a larger area
exposed to high levels  of ozone.  An increase in temperature may
lengthen the duration of high  ozone levels, although the maximum
levels may be the same.  Figure 13-13  illustrates the August 6
base case and climate sensitivity case.  The temperature change
increased the August 6  maximum ozone concentration from 15 parts
per hundred million (pphm) to  18 pphm, a 20% increase in ozone.
The area in which the NAAQS was exceeded almost doubled from
3,700 to 6,600  km2.

     The temperature increases  in the two main cities in the San
Joaquin Valley  (Fresno  and Bakersfield) resulted in an
approximately 0.5 pphm  increase (approximately 8%) in maximum
daily ozone concentration.  In regions farther away from the
emissions, such as the  Sierra  Nevada Mountains, little change in
ozone levels was observed with the increased temperature.

    Midwest and Southeast  Study

    The results from applying  RTM-III  to the midwestern and
southeastern areas are  shown in Table  13-4.  On one particular
day  (July 16) raising the temperature  caused maximum ozone to
increase from 12.5 pphm to 13.0 pphm (Figure 13-14).  Although
this is only a  slight increase (0.5 pphm), the predicted area of
exceedance of the ozone NAAQS-  increased by almost a factor of
three, from 9,800 to 27,000 km2.   The differences  occurred mainly
in the upper Midwest.

Population Exposure

     As discussed above, both  study domains show a significant
area that is exposed to higher levels of ozone when the
temperature is  increased.  Data taken  from the 1980 census from
central California and  the midwestern and southeastern areas were
used to determine the number of people exposed to ozone for the
base case and temperature rise scenarios.   Table 13-5 presents
the number of people-hours of  exposure to ozone concentrations
exceeding 8, 12, and 16 pphm.  These estimates of human exposure
were generated by multiplying the number of people in the grid
cells by the total number of hours that the predicted hourly
                              13-27

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                          Impact of Climate Change on Air Quality
Table 13-3.
Maximum Daily Ozone Concentrations Predicted by the
RTM-III for Each Day of the Central California
Modeling Episodes for the Base Case and the Case of
Climate Sensitivity to Increased Temperature
Maximum Daily Ozone Concentration (pphm)
Day of Episode
August 5, 1981
August 6, 1981
August 7, 1981
August 8, 1981
August 9, 1981
August 10, 1981
Base Case
11.8
15.0
11.7
13.5
10.5
9.1
Increased
Temperature
12.1
18.0
13.1
13.7
11.2
9.18
Percent
Increase
3
20
12
2
7
8
Source:  Morris et al. (1988).
                              13-28

-------
                  Sacramento
   a
San Jose
                Stockton
              a  Mooes to
        Crow's Landing

                 Castle  AFB
                             YosemiXe

                             	v/s.
                                     a  Mooes to
                               Crow's Landing
                                        Castle  AFB   „     \
                                                    Yosemv
             Base Case
                        Climate  Sensitivity  Scenario  il
                                       Eicetda Standard
   Figure 13-13.
Comparison of Predicted Maximum Daily Ozone
Concentrations  (pphm)  for the Base  Case and
Climate  Sensitivity  Scenario No.  1  (temperature
and water increase)  for August 6, 1981
   Source:  Morris et al.  (1988).
                                   13-29

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                          Impact of Climate Change on Air Quality
Table 13-4.
     Maximum Daily Ozone Concentrations Predicted by the
     RTM-III for Each Day of the Midwestern/Southeastern
     Episode for the Base Case and the Case of Increased
     Temperature (Morris et al. 1988).
    Date
              Base
              Case
                               Maximum Daily Ozone
                              Concentrations fpphm)
             Increased
            Temperature
              Percent
              Increase
14 July
15 July
16 July
17 July
18 July
19 July
20 July
21 July
1980
1980
1980
1980
1980
1980
1980
1980
11.3
11.5
12.5
11.7
11.2
13.8
11.-1
12.6
11.3
11.9
13.0
12.0
12.1
14.8
11.2
12.3
 0.0
 3.5
 4.0
 2.6
 8.0
 7.2
 0.9
-2.4
                              13-30

-------
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-------
                          Impact of Climate Change on Air Quality
Table 13-5.  Number of People-Hours of Exposure to Ozone
             Concentrations in excess of 8, 12, and 16 pphm for
             the Base Case and the Case of Climate Sensitivity to
             Increased Temperature (Morris et al., 1988).
                 Exposure to      Exposure to     Exposure to
 Scenario        03 > 8  pphm      03 >. 12 pphm    03 > 16 pphm
               Central California Modeling Episode

Base Case         70,509,216         660,876            0

Increased
Temperature      102,012,064       2,052,143       92,220


            Midwestern/Southeastern Modeling  Episode

Base Case      1,722,590,208      29,805,348            0

Increased
Temperature    1,956,205,568      47,528,944            0
                              13-32

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Chapter  13
ozone concentration  in those grid cells exceeded the 8,  12,  or  16
pphm levels.  Actual exposure levels may be less because indoor
levels are generally lower than ambient air levels.


ECONOMIC, ENVIRONMENTAL, AND ECOLOGICAL IMPLICATIONS

Ozone

    A national  standard  for ambient levels of  ozone was
established with the original Clean Air Act in 1972 along with
standards for five other pollutants.  While headway has  been made
in meeting all  these national air quality standards, progress in
meeting the ozone standard has been particularly slow and
frustrating for concerned lawmakers and environmental officials
at all levels of government.  At the end of 1987, the date
anticipated in  the Act for final attainment of the ozone standard
more than 60 areas had not met the standard.  In recent  years,
the number of nonattainment areas has fluctuated with meteorology
often overwhelming the progress being made through reduced
emissions.  Thus "bad" weather (summertime conditions favorable
to ozone formation)  in 1983 led to an increase in the number of
nonattainment areas while "good" conditions in 1986 led  to a
decline in the  number of areas.

    An increase in ozone levels due to climate change is
important for several reasons:

    o   Ozone levels in  many areas are just below the current
        standard.  Any increase in- ozone formation  is likely to
        push levels  above the standard.

    o   Many inexpensive controls for ozone are already  in place
        in nonattainment areas.  Increases in  ozone levels will
        require relatively expensive measures  to sufficiently
        reduce  ozone precursors to attain the  standard.

    o   The standard itself is defined in terms of the highest
        levels  of ozone  experienced in an area, not average
        levels.   (As a yearly average, no area of the country
        would exceed the standard of 0.12 ppm.)  Thus, a factor
        such as temperature that may have a modest effect on
        average levels of ozone formation may have a much more
        significant  effect on peak levels.

    A rough estimate of each of these factors can illustrate the
potential policy problems created by a rising temperature
scenario.   The data in Figure 13-11 suggest that 5°C degree  rise

                              13-33

-------
                           Impact  of  Climate  Change  on  Air Quality
 in temperature may lead to  an  increase  in peak  ozone
 concentrations of  around 10%.  We can then  ask  what impact a  10%
 increase  in peak ozone  levels  would have on the number  of
 potential ozone violations.  In  the 1983-1985 period  for example,
 68 areas  showed measured exceedances of the ozone  air quality
 standards (for technical and legal reasons  not  all these areas
 were  officially designated  nonattainment areas.)   A 10% increase
 in ozone  levels in that period doubled  the  number  of
 nonattainment  areas to  136.  This would include 41 new  MSAs added
 to the  list and 27 nonMSAs.  These new  nonattainment  areas would
 add most  midsize and some small  cities  in the in the  midwest,
 south and east to  the list  of  nonattainment areas.

    The policy implications of this should  not  be  overstated.
'The temperature is predicted to  rise over a number of years,  and
 the full  effect will not be felt until  well into the  next
 century.   Over the next several  decades, various national
 measures  to reduce ozone precursors, such as a  reduction in the
 volatility of  gasoline,  may go into effect.  These would provide
 a  cushion to marginal areas and  could offset a  temperature
 effect.   However,  other factors  suggest that the temperature
 problem will persist.

    Ozone levels and ozone  precursors are closely  related  to
 economic  expansion and  population growth.   Consumer solvents
 (e.g.,  paints,  sprays,  and  even  deodorants) are a  major source of
 ozone precursors.   These are very difficult to  control  and will
 undoubtedly increase in the future in areas currently attaining
 the standards.   Growth  in other  sources of  ozone precursors would
 bring many areas relatively close to the limits of the  ozone
 standard.   Gradual increases in  temperature would  make  remaining
 in compliance  with the  standard  more difficult.  Although  any
 sudden  change  in the number of nonattainment areas as a result of
 a  secular trend toward  increased temperature is unlikely,  a
 number  of small to midsize  cities eventually may be forced to
 develop new control programs.

    The implications of warmer temperature  rise for existing
 nonattainment  areas can also be  estimated.  In  these  areas
 existing  and planned control measures may not be adequate  to
 reach the standard,  if  additional ozone forms.   In the  past,  EPA
 has attempted  to project the emission reductions and  costs
 associated with the attempts of  existing nonattainment  areas  to
 reach the ozone standard.   Using the same modeling approach,  the
 effects of a temperature increase were  analyzed to estimate the
 additional-tons and costs associated with a projected temperature
 rise.   Extrapolations of existing inventories to the  year  2000
 suggest that higher temperatures could  require  an  additional

                               13-34

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Chapter 13
reduction of 700,000 tons of VOC from an inventory of about 6
million tons.  Given that most current nonattainment areas will
have already implemented the most inexpensive measures, these
additional reductions may cost as much as $5,000 per ton year.
Their aggregate cost could be as much as $3.5 billion each year.

    These conclusions should be viewed as very preliminary.
Nonetheless, they demonstrate that the potential economic
consequences for an already expensive program to combat ozone
could be significant.

Acid Rain

    The global climate change and acid rain issues are likely to
collide in the near future for several reasons:

    First, emissions from fossil fuel powerplants both influence
acid rain and contribute to global warming.  In the future,
global warming may increase energy demand and associated
emissions.  Because the growth of northern electricity demand may
be less than anticipated, regional shifts in the growth emissions
may occur in the future.

    Second, global climate change will influence atmospheric
reaction rates and the deposition and form of acidic material.
It is conceivable that regions of high deposition may shift or
that more acid rain may be transported off the North American
continent.  Strategies that seek to control powerplants in
regions near sensitive areas may or may not be as effective, as
global climate change occurs..

    Third, global climate change will alter the impacts of acid
rain on ecological and other systems in as yet unpredictable
ways.   For example:

    o   Changes in the amount of rainfall may dilute the effect
        of acid rain on many sensitive lakes.

    o   Changes in clouds will alter the fertilization of high
        elevation forests.

    o   Changes in humidity and frequency of rain may alter
        degradation rates for materials.

    o   Increased midcontinental dryness would alter the amount
        of calcium and magnesium in dust, neutralizing impacts
        on Soils.
                              13-35

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                          Impact of Climate Change on Air Quality
    o   Increased numbers of days without frost would decrease
        forest damage associated with frost and
        overfertilization by atmospheric nitrogen.

    o   Changes in snowpack and the seasonality of rainfall will
        change acid levels in streams and alter the timing and
        magnitude of spring shocks an aquatic species.

    Finally, solutions to both problems are inextricably linked
because the implementation of acid rain control measures and ?
life extension programs of many utilities may not occur until
after the year 2010,  that is when global warming may be fully
recognized.  Some solutions,  e.g.,  S02 scrubbers and clean  coal
technologies, may abate acid rain levels, but may do little to
improve or may increase global warming.   Other solutions,
including increased energy efficiency and fuel switching to
natural gas or renewable energy sources, may provide positive
solutions to both problems.

    In summary, an examination of the time horizons of
importance to both acid'rain and global climate change problems
suggests that these two issues can no longer be viewed in
isolation.  Emissions,  atmospheric reaction rates, pollutant
transport, and environmental impacts will be altered by climate
change.  This suggests that a more holistic approach must be
taken to air pollution problems and that proposed solutions
should be evaluated on the basis of their contributions to
solving both problems.

Carbon Monoxide

    While global warming as a general rule will exacerbate major
pollution problems,  it may actually have a modest positive effect
on the problem of carbon monoxide (CO)  nonattainment.   This is
because most CO violations occur during the winter months,  and
that automobile CO emissions (the primary source of CO)  are
greatest under cold start conditions.   With slightly warmer
conditions overall,  there should be some lessening of the CO
problem.


POLICY IMPLICATIONS

    The Environmental Protection Agency issues air pollution
regulations to improve air quality and to protect public health
and welfare.  In general, current regulations to reduce oxidant
levels will also provide positive benefits toward a goal of
limiting the rate of growth in global warming.  Other programs

                              13-36

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Chapter 13
aimed at reducing carbon monoxide levels, particularly from
mobile sources, or CFCs to protect the stratospheric ozone layer,
also positively affect greenhouse gases and the rate of global
warming.  However, the regulatory activities of the Agency have
not been retrospectively reviewed to determine their impacts on
global warming.  In some cases there may be important benefits;
for example, current emission standards for automobiles do not
encourage more efficient use of gasoline.  A different form of
standard, while potentially disruptive to air pollution efforts,
might produce positive greenhouse gas benefits via reduced energy
consumption.  These types of analyses will have to be performed
in the future.

    Because  of the climate change issue, the following are some
of the more  important policy issues:

    o    Air  pollution control agencies such as EPA should
         undertake a broad review to determine the impact  of
         global climate change on air pollution policies.  In
         particular, the cost of added controls resulting  from
         climate change should be determined, perhaps as each
         significant regulation is proposed or reevaluated.

    o    The  impact of EPA regulations, particularly the impact
         on energy use and greenhouse gases, should be a more
         important weight in future regulatory decisions.  Since
         EPA  regulations often serve as models for other
         countries, the energy penalty, while sometimes small in
         the  United States, may be important on a global basis.

    o    Future reports to Congress and major assessments  of
         ecological effects, e.g., the 1990 Acid Deposition
         Assessment document, should include sensitivity analyses
         of alternative climates.  Risk management decisions of
         the  Agency could then be made with improved knowledge of
         climate impacts.


Recommendations for Further Research

    Some of  the key questions which need to be resolved
regarding climate change and air quality include the following:
How important will climate change be relative to other factors
such as population growth to future air pollution problems?  Is
the impact of climate change likely to be significant enough so
as to require totally different air pollution strategies?  What
mix of control strategies could be most cost effective in
reducing acid rain,  global warming,  tropospheric ozone and other

                              13-37

-------
                          Impact of Climate Change on Air Quality
pollution problems?  The research elements needed to address
these issues include basic research, sensitivity analyses, full
scale atmospheric modeling, and cost effectiveness studies.
Examples are presented below:

Basic Research:  There is an important need to understand how
manmade and natural emissions of hydrocarbons and other
pollutants might change in the future when temperatures, C02,  and
UV-B radiation increase and other climate parameters vary.

Sensitivity Analyses:  Analyses of ozone concentrations are
dependent on boundary layer height, clouds, water vapor, wind
speed, UV-B radiation and other parameters.  Sensitivity tests
using single models could improve our understanding of the
relative importance of these variables and could provide
important information for general circulation modelers.

Full Scale Modeling - Complete understanding of the interactions
of climate change and air quality will ultimately require that
general circulation models and mesoscale chemistry models be
linked in some direct or indirect manner.  This will require the
development of innovative approaches between the general
circulation and air pollution modeling communities.             .    fl

Cost Effectiveness Studies - There are currently a number of
Congressional proposals to improve the Clean Air Act and to
reduce global climate change.  In order to assume that both air
quality and global climate change goals are achieved, analyses of
the cost effectiveness of alternating strategies will be
necessary.
                              13-38

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Chapter 13
REFERENCES

Altshuller, A.P., and J.J. Bufalini. 1971.  Photochemical aspects
of air pollution.  Environmental Science and Technology 5:39-64.

Ching, J.K.S., J.H. Novak, K.L. Schere, and F.A. Schiermeier.
1986.  Reconciliation of Urban Emissions and Corresponding
Ambient Air Concentrations Using Mass Flow Rate Technique. Draft
report prepared for EPA/ORD; April.

Dodge, M.C. 1977.  Effect of Selected Parameters on Predictions
of a Photo-chemical Model.  EPA-600/3-77/048; June.

Galloway, J.N., G.E. Likens, W.C. Keene, and M.M. Miller. 1982.
The composition of precipitation in remote areas of the world.
Journal of Geophysical Research 87:8771-8788.

Galloway, J.N., D.M. Whelpdale, and G.T. Wolff.  1984.  The flux
of sulfur and nitrogen eastward from North America.  Atmospheric
Environment 18:2595-2607.

Gery, M.W., R.D. Edmond, and G.Z. Whitten. 1987.  Tropospheric
Ultraviolet Radiation:  Assessment of Existing Data and Effect on
Ozone Formation.  EPA Report 600/3-87/047; October.

Hales J.  1988. In:  Sensitivity of Urban/Regional Chemistry to
Climate Change: Report of the Workshop.  Chapel Hill, NC; Feb.
17-18.

Holzworth, G.C.  1972.  Mixing Heights, Windspeeds and Potential
for Urban Air Pollution Throughout the Contiguous United States.
,EPA, Research Triangle Park, NC.  Office of Air Programs
Publication No. AP-101.

Kamens, R.M., H.E. Jeffries, K.G. Sexton, and A.A. Gerhardt.
1982.  Smog Chamber Experiments to Test Oxidant-Related Control
Strategy Issues.  U.S. EPA Report 600/3-82-014; August.

Keene, W.C., J.N. Galloway, and J.D. Holden Jr.  Measurement of
weak organic acidity in precipitation from remote areas of the
world.  Journal of Geophysical Research  88:5122-5130.

Keene, W.C., and J.N. Galloway.  1984.  Organic Acidity in
precipitation of North America.  Atmospheric Environment 18:
2491-2497.
                              13-39

-------
                          Impact of Climate Change on Air Quality
Lamb B.K., H.H. Westberg, T. Quarles, and D.L. Flyckt.  1985.
Natural Hydrocarbon Emission Rate Measurements From Selected
Forest Sites.  EPA-600/3-84-001; October.

Norton, R.B.  1985.  Measurements of Formate and Acetate in
Precipitation at Niwot Ridge and Boulder, Colorado.  Geophysical
Research Letters 12:769-772.

Ramanathan, V., R.J. Cicerone, H.B. Sing, and J.T. Kiehl.  1985.
Trace gas trends and their potential role in climate change.
Journal of Geophysical Research 90:5547-5566.

Research Triangle Institute.  1975.  Investigation of Rural
Oxidant Levels as Related to Urban Hydrocarbon Control
Strategies.  EPA-450/3-75-036; March.

Schertz, T.L., and R.M. Hirsch.   1985.  Trend analysis of weekly
acid rain data—1978-1983.  U.S. Geological Survey, Water
Resources Investigations Report 85-4211.

Seilkop, S.K., and P.L. Finkelstein.  1987.  Acid precipitation
patterns and trends in eastern North America, 1980-84.  Journal
of Climate and Applied Meterology 26(8):980-994.

U.S. EPA.  1988.  U.S. Environmental Protection Agency, Office of
Air Quality Planning and Standards.  National Air Quality and
Emissions Trends Report, 1986.  Research Triangle Park, NC.  EPA
report No. 45014-88-001.

Walcek C.  1985.  In: Sensitivity of Urban/Regional Chemistry to
Climate Change: Report of Workshop.  Chapel Hill, NC; Feb. 17-18.
                                                                     I
                              13-40

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                            CHAPTER 14

                          HUMAN HEALTH

FINDINGS

Global warming may lead to increases in morbidity and mortality
during the summers, particularly among the elderly.  These
effects may be more pronounced in some regions than in others,
with northern regions more vulnerable to the effects of higher
temperature episodes than southern regions.  Milder winters may
offset increases in morbidity and mortality, although net
mortality may increase.  If people become acclimatized to the
warmer temperatures by using air conditioning, changing work
place habits, and altering the construction of homes and cities,
the impact on summer mortality rates may be substantially
reduced.  The full scope of the impacts of climate change on
human health remains uncertain and the subject for future
research.

o    Although there may be increases in weather-related summer
     deaths due to respiratory, cardio-, acular, and
     cerebrovascular disease, there may be decreases in weather-
     related winter deaths for the same diseases.  In the United
     .States, however, on average, weather-related deaths are
     greater in summer than in winter.   Thus, global warming
     could produce a net increase in deaths.

o    Sudden changes in temperature are correlated with increases
     in deaths.  So if climatic variability increases, morbidity
     and mortality are also likely to increase.  A decrease in
     the frequency or intensity of climate extremes is likely to
     be associated with a decrease in mortality and morbidity.

o    Seasonal variation of fetal and infant mortality (higher in
     the summers, lower in the winters)  is thought to be due to
     summertime increases in infections.  The longer and hotter
     summers that may accompany climate change may exacerbate
     this effect at least in some regions.

o    Vector-borne diseases,  such as those carried by ticks, fleas
     and mosquitos, could increase in certain regions.  In
     addition,  climate change may alter habitats.  For example,
     some forests may become grasslands, thereby modifying the
     incidence of vector-borne diseases.

o    While uncertainties remain about the magnitude of other
     effects, it's climate change could have the following
                               14-1

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                                                     Human Health
     impacts:
          Increases in summer rainfall would multiply the amount
          of ragweed growing on cultivated land.

          Changes in humidity may heighten the incidence and
          severity of skin infections and infestations such as
          ringworm, candidiasis, and scabies.

          Increases in the persistence and level of air pollution
          episodes associated with climate change will have
          adverse health effects.
CLIMATE-SENSITIVE ASPECTS OF HUMAN HEALTH

     Human illness and mortality are linked in many ways to the
environment (Figure 14-1).   Mortality rates, particularly for the
aged and very ill, are influenced by the frequency and severity
of extreme temperatures.  The life cycles of disease-carrying
insects, such as mosquitoes and ticks, are affected by changes in
temperature and rainfall, as well as by modifications in habitat
that result from climate change.  Air pollution, frequently
associated with climate change, is known to increase the
incidence or severity of respiratory diseases such as emphysema
and asthma.  Climate variables have been implicated in affecting
such chronic diseases as stroke and heart disease, such
contagious diseases as influenza and pneumonia, such allergic
diseases as asthma and hay fever,^and such vector-borne diseases
as encephalitis and Lyme disease.   In addition,  adverse  effects
on reproduction, such as increased incidence of premature births,
are associated with certain seasons.  Table 14-1 lists the number
of deaths and the number of physician visits (used to estimate
the amount of illness associated with a given effect) associated
with major causes of mortality and illness in the United States.
      Vector-borne  diseases are those that are spread to humans or
animals by an insect, such as a mosquito or tick.  The agent is the
disease-causing organism, such  as a virus,  that is  carried and
transmitted by the vector.  Some  vectors,  such  as  ticks,  live on
other animals, such as deer and birds, which are called hosts.  For
example, Lyme disease is caused by a bacteria (the agent),  which
is carried by a certain specie of tick (the vector),  which lives
on deer and mice (the hosts).
                               14-2

-------
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-------
                                                             Human Health
Table 14-1.
Major Causes of Illness and Mortality in the United States
(1984)a



Cause of Illness or Mortality
Accidents and adverse effects
Malignant neoplasms
Heart diseases
Suicides, homicides
Chronic liver disease
and cirrhosis
Cerebrovascular diseases
Congenital anomalies
Chronic obstructive pulmonary
diseases and allied conditions
Diabetes mellitus
Pneumonia and influenza
Estimated
Number of
Physician
Contacts
70,000,000
20,300,000
72,400,000
-

1,400,000
9,100,000
4,300,000

20,500,000
35,600,000
14,500,000


Estimated Mortality

Number
93,520
453,660
763,260
47,470

26,690
154,680
12,900

70,140
35,900
58,800

Rate/100,000
39.6
192.1
323.2
20.1

11.3
65.5
5.5

29.7 j
5.2 1
24.9
   Total for weather-sensitive
   diseases
                       152,100,000
1,082,780
448.5
     Total all causes
                       248,100,000
1,717,020
717.1
aConditions that can be influenced by changes in weather and climate
 are indicated in bold type.

Source: CDC (1986).
                                       14-4

-------
Chapter 14
General Mortality and Illness

     The relationship between mortality and weather has been
studied for over a century with the  (Kutschenreuter, 1959;
Kalkstein, Vol. _) relationship between mortality and temperature
receiving the most attention.  Kutschenreuter  (1959) observed
"mortality is higher during cold winters and hot summers and
lower during warm winters and cool summers."  As indicated in
Figure 14-2, the people most sensitive to temperature extremes
are the elderly.   Picciotto, 1985).  One possible explanation is
that for individuals already stressed by the circulatory problems
associated with vascular and heart disease, heat waves "overload"
the thermoregulatory system, which is struggling to maintain the
appropriate body temperature.  This results in heat stress,
heatstroke, and often mortality as well (White and Hertz-
Picciotto, 1985).

     In addition to the elderly, people working in hot
environments, such as steel mills and construction sites, are at
special risk from heat waves (Dukes-Dobos, 1981).  These workers
face even greater risk if they have underlying medical problems
such as the following:

o  impaired circulation;
o  lack of acclimatization/physical conditioning;
o  higher than normal body temperature due to disease or
   exercise;
o  chronic diseases such as alcoholism, diabetes, and
   obesity;
o  reduced ability to sweat due to medications; and/or
o  previous heat-related illness.

Cardiovascular, Cerebrovascular, and Respiratory Diseases

     Although more information exists on the relationship of
climate to total mortality from all causes, there is substantial
information indicating that changes in climate variables are
associated with impacts on the cardiovascular, cerebrovascular,
and respiratory systems.  As previously shown in Table 14-1,
diseases or dysfunction of these three systems cause the majority
of deaths observed on a yearly basis in the United States, as
well as significant illness.  Incidences of these diseases rise
as climate extremes increase.

     Changes in temperature may affect a number of heart problems
including heart attack,  coronary heart disease, and possibly
coronary atherosclerosis and rheumatic heart disease (Vuori,
1987) .   Various stroke-related diseases are also thought to be

                              14-5

-------
              N D J
            260
240


220


200


130


120


MO


100-
             MONTHS
        M A M J J A S O N D J  f M
          "  ~  i i  i -TT~rr~[ ~
                    	.--li
                    ion   /  I
                            \ Data
240


220


200
                                        BO  45. to 64-year-old


                                        70
              '	^\/	
               __i	i  i j i__i. i  rr!.i _L_L j	i_j—L__
              NDJ  FMAMJJ ASONDJ FM
                                           Total deaths
                                        30


                                        20


                                        10  65-year-old and over


                                        00
                          MONTHS


Figure  14-2.  Annual Mortality  for All Age Groups for  1949-58 a,b
^Temperature curves  are based on  1921-50 monthly normal
 temperatures.
bMortality curves are based on daily average  mortality for each
 month  computed from 1949 to 1958 monthly totals of mortality
 reported for all age groups.

Source:   Kutschenreuter (1959).
                                 14-6

-------
Chapter 14
affected by weather  (Gill et al., 1987).  Respiratory diseases
sensitive to weather include pneumonia, bronchitis, influenza and
other respiratory virus infections, asthma, and hay fever.  A
number of respiratory ailments have been linked to air pollution,
which varies seasonally because it is affected by changes in
weather.  Increases in the incidence of lung cancer, emphysema,
chronic bronchitis, and asthma have been attributed to the
presence of industrially and photochemically produced pollutants
present in urban smog (Lopez and Salvaggio, 1983).

     The exact relationship between temperature changes and
illness from diseases such as heart attack and stroke is not as
clear cut as the relationship reported for mortality from these
diseases and temperature because mortality has national reporting
procedures whereas illness has to be estimated from such data as
hospital admission figures.  In the few studies that have
evaluated illness from cardiovascular or cerebrovascular disease,
admissions have shown a relationship to weather changes similar
to that observed for mortality (Sotaniemi et al., 1970; Gill et
al., 1988).

     Illness from respiratory diseases is somewhat easier to
estimate, principally because two such diseases, asthma and hay
fever, affect as much as 3 and 6% of the U.S. population,
respectively, causing significant losses in work time.  The most
common seasonal pattern for the allergic type of asthma and for
hay fever is an increased occurrence during the spring in
response to grass pollens.  A nonseasonal form of allergic asthma
may also occur in response to allergens such as molds, which are
affected by changes in precipitation and temperature.

Vector-Borne Diseases

     Two tick-borne diseases currently posing a public health
problem in the United States, Rocky Mountain spotted fever and
Lyme disease, induce similar initial symptoms: high fever,
chills, headache, backache, and profound fatigue.  Rocky Mountain
spotted fever can eventually result in hemorrhagic areas that
ulcerate,  and Lyme disease may cause permanent neurologic,
cardiac, and rheumatologic abnormalities (APHA, 1985).  The ticks
that spread these diseases, and therefore the geographic
distribution of the diseases themselves, are affected both
directly and indirectly by climate variables.  Such environmental
factors as temperature,  humidity,  and vegetation directly affect
tick populations and the hosts of the tick populations, e.g.,
deer,  mice,  and birds.
                               14-7

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                                                     Human Health
     Mosquito-borne diseases, such as malaria and certain types
of encephalitis (inflammation of the brain),  are not a major
health problem in the United States today because occurrences are
relatively rare.  However, mosquitoes are also weather-sensitive
insects favoring a warm, humid climate.  The spread of mosquito
populations and the diseases they carry depends in part upon such
climate factors as temperature, humidity, and upon vegetation,
which is also influenced by the climate.

Human Reproduction

     Preterm delivery (i.e., premature birth) and perinatal
mortality (i.e., death just before, during, or just after birth)
are two adverse reproductive outcomes that are associated' with
particular seasons and,  thus, might be affected by climate
change.  Statistically significant increases in preterm births
and in perinatal mortality in the summer months have been
documented (Keller and Nugent, 1983; Copperstock and Wolfe, 1986)
(see Figure 14-3).  The data on total perinatal deaths correspond
closely with those on perinatal deaths associated with infection
in the mother or infant, suggesting that the seasonality in
perinatal death observed is linked to a seasonality of
reproductive infections (Keller and Nugent, 1983).

POTENTIAL HUMAN HEALTH EFFECTS OF CLIMATE CHANGE

     To assess the effects of climate change on human health, EPA
sponsored three studies for this report (Table 14-2).  Wiseman
and Longstreth (1988) reviewed the literature on the role of
climate, season, and weather variables in the incidence of, and
mortality due to,  vector-borne diseases, and they evaluated the
potential impact of climate change on these diseases in the
United States.  They also conducted a workshop of eminent
scientists to evaluate the potential impacts of global climate
change on vector-borne infectious diseases in the United States.
Following the workshop,  Haile (1988) conducted modeling studies
of the potential impact of climate change on 1) the distribution
of the American dog tick,  vectors of Rocky Mountain spotted
fever, and 2)  the potential for malaria transmission in the
United States.  The third study, by Kalkstein  (1988), was an
extension of an earlier modeling study that assessed the
potential effects of global climate change on the elderly and on
total mortality in New York (Kalkstein et al., 1986).  In
Kalkstein (1988),  the New York analysis was expanded to include
14 other cities.  A detailed review of these three studies,
supplemented with other information from the literature, is
presented in this section.

                               14-8

-------
                                                         Human Health
  [a]
                             A  M  J   J   A  S  0
                                Month of Year
      N  D
 [b]
                                                     Preterm
                                                     Births
                          M  A  M  J  J  A
                                Month of Year
SON
Figure 14-3.   Probabilities of  Perinatal Death  [a]  or Preterm
               Delivery [b]
 Source:   Keller and Nugent  (1983).
                               14-9

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                                                     Human Health
Table 14-2.  Studies Conducted for This Report.
   "The Impact of CO2  and  Trace  Gas  -  Induced Upon Human
   Mortality"  Kalkstein,  University of Delaware.

   "Computer Simulation of the Effects of Changes  in Weather-
   Pattern on Veetor-Borne Disease Transmission"  Haile, U.S.
   Department of Agriculture.

   "The Potential Impact of Climate Change on Patterns of
   Infectious Disease in the United States"  Longstreth,
   IGF/Clement Associates, Inc.

   "Effect of Climatic Warming on Populations of the Horn Fly"
   Schmidtmann and Miller, Agricultural Research Service

   "Changing Animal Disease Patterns Induced by the Greenhouse
   Effect"  Stenn, Mertz,  Stryker and Huppi, Tufts University.
                              14-10

-------
Chapter 14
General Mortality

     Preliminary analyses suggest that unless the U.S. population
becomes fully acclimatized  to higher temperatures,  climate
change will be associated with a rising number of summer deaths.
In addition, if climate change causes more intense heat waves,
mortality is likely to increase.  In the absence of complete
acclimatization to warmer winters, the number of winter deaths is
also likely to decline.  With acclimatization, mortality may not
decrease.  It is not clear what the net effect of these two
offsetting trends may be.

    There have been very few studies of the effects of global
climate change on human mortality.  All of the identified effects
have come from a single group of investigators: Kalkstein and his
colleagues from the Center for Climate Research at the University
of Delaware.  This group (Kalkstein et al., 1986) developed a
regression equation .involving nine weather elements, such as
temperature, windspeed, and humidity, to give the best algorithm
for describing the current impact of weather on mortality.  The
algorithm used mortality data from New York City for 19'64-66,
1972-78, and 1980.

     The analysis revealed the existence of a summertime
"threshold temperature" — the maximum temperature above which
mortality increases — of 92°F for total deaths.  This
information was then used to assess the potential impact of
climate change due to the emission of greenhouse gases, under the
assumption that the population would not acclimatize, as well as
under the assumption that it would acclimatize.   Unacclimatized
impacts were estimated by combining the climate scenarios and the
historical weather algorithm described above, and acclimatized
impacts were estimated by developing analogue cities that have
weather variables today that look like those New York is
estimated to have under climate change.
     Under full acclimatization and a scenario predicting that
New York will be 5 to 7°F warmer than it is today, no additional
deaths were predicted.  However, assuming no acclimatization, the

     'Estimations  of the impact of warming on  future mortality must
address  the   guestion  of   whether  humans   will  acclimatize
(physiologically adapt) to changing  weather.   How quickly humans
may become acclimatized is a topic of considerable controversy, so
it  is  difficult  to  predict  whether the  climate  changes  being
predicted will occur sufficiently slowly to allow acclimatization.
                              14-11

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                                                     Human Health
number of summertime deaths attributable to temperatures above
the threshold increased seven to ten-fold.  Changes in winter
weather were not estimated to affect mortality.

     For this report, Kalkstein extended the New York analysis to
cover 14 additional metropolitan areas and to evaluate the impact
of two climate scenarios:  the  GISS doubled C02  scenario,  and
the GISS transient A scenario, evaluated at 30 years and at 60
years past the base period.  Threshold temperatures were
calculated for each city for summer and winter.  Historical
relationships between mortality and weather were derived
independently for each of these 15 cities for both summer and
winter.  Table 14-3 summarizes the results for total mortality,
by city and by season (summer or winter), for the doubled C02
scenario with and without acclimatization.

     The cities with the highest estimated number of weather-
associated summer deaths historically were New York City,
Chicago, and Philadelphia:  each averaged over 100 weather-
induced deaths per summer.  All of the cities with the highest
average number of summer deaths are in the Midwest or Northeast,
and those with the lowest number of summer deaths are in the
South.

     In the absence of any acclimatization, total summertime
mortality in the United Stated under conditions of doubled C02 is
estimated to rise from an estimated current total of 1,156 deaths
to 7,402 deaths, with deaths in the elderly (aged 65 or over)
subset contributing about 70% of each figure (727 and 4,605,
respectively).  Currently, the percentage of elderly in the U.S.
population is increasing.  Thus, the number of mortalities
estimated to result from climate change may be larger than that
found by Kalkstein because his analysis is predicated on today's
age distribution.  Even with full acclimatization, the number of
weather-associated summer deaths approximately doubles to 2,198,
possibly because hot weather increases physiological stress.
Kalkstein's analysis also estimates a drop in the number of
wintertime deaths.  Historically, however, the number of weather-
related deaths during the winter in the United States is much
smaller (243) than that observed for the summer,  and winter
deaths were estimated to fall to 52 without acclimatization and
to 159 with acclimatization.  The net result for the United
States is an increase in yearly mortality associated with doubled
C02.
                              14-12

-------
        Chapter 14
Table 14-3. Estimated Future Mortality Under Doubled C02 Climate Condition:
Without and With Acclimatization


City
Atlanta
Chicago
Cincinnati
Dallas
Detroit
Kansas City
Los Angeles
Memphis
Minneapolis
New Orleans
New York
Oklahoma City
Philadelphia
Saint Louis
San Francisco
Total


Current
18
173
42
19
118
31
84
20
46
0
320
0
145
113
27
1,156
Number
Summer
Without
159
412
226
309
592
60
1,654
177
142
0
1,743
0
938
744
246
7,402
of Deaths per Season

With
0
835
116
179
0
138
0
0
235
0
23
47
466
0
159
2,198

Current
2
46
14
16
16
21
0
0
5
0
56
0
10
47
10
243
Winter
Without
2
2
6
1
2
5
0
0
1
0
18
0
1
7
7
52

With
0
96
0
0
37
0
0
0
0
0
25
0
1
0
0
159
Source:  Kalkstein (1988)
                                      14-13

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                                                     Human Health
Cardiovascular/ Cerebrovascular, and Respiratory Diseases

     Overall global warming and climate change may exacerbate the
effects of cardiovascular, cerebrovascular, and respiratory
diseases.  Data show an inverse relationship between mortality
and temperature (i.e., deaths go down as temperature goes up) for
the range between -5°C and about +25°C, with sharp increases at
temperatures above and below this range, particularly for the
elderly and for hot weather (White and Hertz-Picciotto, 1985).*
Data illustrating this relationship for coronary heart disease
and stroke are shown in Figures 14-4 and 14-5, respectively
(Rogot and Padgett, 1976).  This complex relationship precludes
simple prediction of the net effect of climate change.  For
example, while it seems likely that hot weather-associated
mortality from these diseases will increase in many localities,
this trend is likely to be offset, at least in part, by a
decrease in cold weather-associated mortality.

     Just as higher summer temperatures are associated with
increases in mortality from cardiovascular, cerebrovascular, and
respiratory diseases, they are also likely to be associated with
increases in the occurrence of these diseases.  Particular stress
may be put on the respiratory system because climate change can
increase pollen, urban smog (discussed below), and heat stress.

     For example,  if, as has been suggested in the chapter on
forests, climate change encourages a transition from forest to
grassland in some areas, grass pollens could increase.  This, in
turn, may increase cases of pollen-induced hay fever and allergic
asthma.  (However, the switch from forest to grassland would
reduce the amount of tree pollens that also cause allergic
responses in some individuals.)  Rises in humidity also may
affect the incidence of mold-induced asthma and hay fever.

     As indicated in the chapter on air pollution, global warming
may modify global and regional air pollution because it is likely
to be associated with changes in the concentrations of ozone and
may also have impacts on acid deposition and general oxidant
formation.   Increasing occurrences of numerous respiratory
diseases, such as lung cancer, emphysema, bronchitis, and asthma,
have been attributed to the pollutants in urban smog (Lopez and
Salvaggio,  1983).   Many of the trace gases implicated in global
warming contribute to these problems; other chemicals are created
     *The exact range appears  to  depend  on  the  city.
                              14-14

-------
                                                           Human Health
                                                      so

                                                      40

                                                      30


                                                      20
             -20   0   20  40  SO  80  100   0  20  40  60  80  100  F
             -29  -18   -7  4  16  27  38  -18  -7   4  16  27  38  C

                     AVERAGE TEMPERATURE ON DAY Of DEATH
Figure 14-4.   Relationship  of Temperature  to Heart  Disease
                Mortality

Source:  Rogot and  Padgett  (1976).

                                  14-15

-------

                                     S' Louis
                                                    Honolulu
                                                        A
                                                  101 Angdn
                                               San
               -20  0
               •29-18
                                           X


                                           20

                                           8
                                           7
                                           6
                                           5

                                           4

                                           3.
                                                                 1
                                                                 5

                                                                 4

                                                                 3
                                                                 2.5
20  40  60   80  100     0   20   40   60  80  100 '" F
-7   4  16   27  38   -IB -7   4   16  27  3fl   C
   AVERAGE TEMPERATURE ON DAY OF DEATH
Figure 14-5.   Relationship of Temperature  to Mortality From
                Stroke

Source:  Rogot and Padgett  (1976).

                                   14-16

-------
Chapter 14
from the interaction of ultraviolet light with these and other
chemicals present in the atmosphere.

     The component that causes the greates concern is urban smog
(Grant, 1988). If global warming causes an increase in
tropospheric ozone, serious consequences could result for adult
asthmatics and people who suffer from acute or chronic
bronchitis.

Vector-Borne Diseases

     The changes in humidity and temperature caused by the
increase in greenhouse gases are likely to alter the geographic
ranges and life cycles of plants, animals, insects, bacteria, and
viruses.   (For further discussion of forestry and agriculture,
see Chapter 11, Forestry, and Chapter 10, Agriculture.)  For
example, the range of many plant pests may move northward by
several hundred miles. Such changes are also likely to occur for
insects that spread diseases to both humans and animals.  Vector-
borne diseases are relatively rare in the United States, although
most of those found in the United States are increasing in
incidence.  Some, such as Lyme disease, are increasing
dramatically (CDC, 1986).

Tick-Borne Diseases

     Both Rocky Mountain spotted fever and Lyme disease are
considered to be public health problems in the United States.
Although these two diseases are spread by different species of
ticks, some overlap exists in their geographic distribution
(Figure 14-6).  Because tick populations appear to be limited by
the size of their host populations, the spread of tick-borne
diseases may be particularly sensitive to any change that may
affect the geographic range of these hosts and, consequently, the
range of the vector, or carrier.

     In addition to the presence of the host, tick populations
also depend upon the seasonality of environmental factors such as
temperature, humidity, and vegetation.  Optimally, climate must
be warm enough to promote progression through the life cycles,
humid enough to prevent the drying out of eggs, and cold enough
in winter to initiate the resting stage.

     As for many tick-borne diseases, the opportunity for a tick
to acquire the infective agent from an infected animal is limited
to the short period when the level of the agent in the blood of
the host is high enough for the tick to receive an infective
dose.  Higher temperatures may increase the amount of the agent

                              14-17

-------
                            LYME DISEASE
                   ROCKY MOUNTAIN SPOTTED FEVER
    States With Highest
    Incidence (Cases Per 100K)
    NC 3.6, SC 3.2, OK 2.3
No. of Cases
n  0-10
82  1°-25
H  25 - 100
£1 100-226
Figure 14-6.   Geographic Distribution of Lyme Disease and Rocky
               Mountain Spotted  Fever

Source:  Wiseman and Longstreth (1988).

                               14-18

-------
Chapter 14
 (the organism that is transmitted by the carrier, such as a
virus) and the time it remains lodged on the host animal.  Both
of these mechanisms will increase the rate of infection of the
carrier.  However, although higher temperatures may favor the
presence of the agent, there is some indication that they could
disrupt the life cycle of some tick species.  In these cases,
warmer temperatures would reduce both tick survival and the
spread of diseases they carry.

     Tick populations also vary with the natural vegetation of an
area.  The incidence of Rocky Mountain spotted fever, in
particular, has been linked to natural vegetation and changes in
climate.

     In examining the potential impact of climate change in the
United States on Rocky Mountain spotted fever, Haile used a
weather-based model, ATSIM, to evaluate the impact of the
scenario climate changes on the distribution of the American dog
tick, the primary carrier of this disease (Haile, 1988; Mount and
Haile, 1988).  The model uses data inputs from the three GCMs to
estimate population dynamics, growth rate, and generation time
under the various scenarios.  Haile assumed that habitats and
host density did not change in response to global warming.
Sample results for six cities representing the most southern, the
most northern, and the  two middle latitudes are presented in
Figure 14-7.  The results indicate that under all scenarios, tick
populations would shift from south to north and would be
virtually eliminated from the most southern locations
(Jacksonville and San Antonio).  However, in the middle latitude
cities, the results are mixed and depend on the scenario
evaluated.

     In this analysis, the only model inputs that were changed to
simulate climate change were the weather inputs.  Other important
parameters in the model are the distribution of habitat between
forests and meadows and the presence of suitable hosts.  Both
parameters are likely to be changed relative to current
conditions under climate change.  As indicated in the chapter on
forests, a change from forests to meadow may occur in certain
areas of the country; this would depress the tick population.
However, the distribution of small mammals also may change.  If
small mammal populations increased, tick populations would grow.

     In a sensitivity analysis of their model, Mount and Haile
(1988)  found that the model predictions could vary sixteenfold,
depending on the inputs used for host density, whereas the
variability conferred by changes in the weather inputs is about
fourfold.  Based on the sensitivity analysis, host densities are

                              14-19

-------
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Chapter 14
extremely important to these predictions.  Keeping them constant,
as was done in this analysis, could have underestimated the
impact of climate change on the density of the American dog tick.

Mosquito-Borne Diseases

     A second category of vector-borne diseases that can be
affected by climate change consists of diseases carried by
mosquitoes.  Climate changes resulting in more days between 16
and 35°C, with humidity between 25 and 60%, are likely to favor
the growth of mosquitoes (White and Hertz-Picciotto, 1985).
Mosquito populations are also sensitive to the presence of
standing water, which may or may not increase.

     Worldwide; mosquito-borne diseases are associated with
significant illness and mortality.  In the United States,
however, vector control programs and improved hygiene have
virtually eliminated endogenously transmitted cases of these
diseases, with the exception of sporadic outbreaks of
arbovirus-encephalitis.  (Imported cases are seen occasionally.)
Numerous mosquito species are- present in the United States,
however.  Recent restrictions on pesticide use, coupled with the
influx of visitors and immigrants who can serve as sources of
infectious agents, as well as the lack of available vaccines for
many of the potential diseases, suggest the potential for
reintroduction and establishment of these diseases in the United
States — particularly if global warming provides a more suitable
climate for their growth and development (Wiseman and Longstreth,
1988) .

     Although there are numerous mosquito-borne diseases, at a
recent workshop five were considered to pose a potential risk to
U.S. populations if the status quo is disturbed by climate change
(Wiseman and Longstreth, 1988).  Malaria, dengue, and afbovirus-
induced encephalitis were considered to be significant risks, and
yellow fever and Rift Valley fever were considered to be possible
risks.

     Malaria

     Malaria is an infectious disease transmitted by mosquitoes
and induced by parasites (Plasmodia).   The symptoms are highly
variable, depending on the species of the agent.  They include
chills,  sweats, and headache, and in severe cases, may progress
to liver damage and even liver and renal failure.

     Owing to effective vector control and treatment programs,
malaria is no longer indigenous to the United States.  However,

                              14-21

-------
                                                     Human Health
imported cases occur regularly, and occasionally indigenous
transmission has been documented (Wiseman and Longstreth, 1988).
Current demographic trends in the United States, including a
large number of legal and illegal immigrants from locations where
malaria is endemic, could result in the presence of a sufficient
pool of infected individuals that in conjunction with climate
changes may create sufficiently favorable conditions for
increased incidence of the disease.

     Haile used the weather-dependent model MALSIM to evaluate
the potential impact of climate change on malaria in an infected
population living in an area where a competent carrier is
present.  The MALSIM model showed that several cities in the
South (e.g., Miami, Key West, and Orlando) under current climate
conditions are very favorable for malaria transmission. In
general, however, very little change was estimated for the
transmission potential of malaria in the United States (Figure
14-8).  In a few cities, e.g., Richmond, Nashville, and Atlanta,
the model estimated large increases in one scenario relative to
those that would occur normally.  However, the results varied
with different climate scenarios and did not occur at all
locations.

     Dengue Fever

     Dengue fever is an arbovirus-induced* illness  characterized
by fever, rash, and severe pain in the joints.  Like malaria, it
is not currently endemic in the United States, although potential
carriers are present (see Figure 14-9) and the disease is
imported here regularly by people who have traveled abroad.

     The first infection by the virus generally is not fatal.
However, a second infection, particularly by a type of virus
different from the first, can result in much more serious forms
of the disease that can be fatal, particularly in the very young
and the elderly.

     The ability of the vector to transmit the agent appears to
depend on temperature,  and current conditions do not appear to be
favorable for this process.  Climate changes that raise
temperatures, however,  may reduce the required incubation period

     *An  arbovirus   is   a  virus  transmitted  by  an  arthropod.
Arthropods are a group of animals that include insects and
crustaceans.  Examples of arthropods that transmit disease
include mosquitoes and ticks.


                              14-22

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Chapter 14
and increase the infectivity of the carrier, increasing the
potential transmission of the disease.

     Arbovirus-Related Encephalitides

     Arbovirus-related encephalitides are a group of acute
inflammatory diseases that involve parts of the brain, spinal
cord, and meninges. In mild cases, these infections result in
feverish headaches or aseptic meningitis; in more severe cases,
those symptoms can be accompanied by stupor, coma, convulsions
(in infants), and occasionally spastic paralysis  (APHA, 1985).

     At least eight types of viruses causing encephalitis are
present in the United States.  Cases range in severity depending
on the type of virus, with yearly fatality rates between 0.3 and
60%, These infections are rare.  In 1984, 129 cases were reported
to the Centers for Disease Control, which maintains an active
surveillance program for them (CDC, 1986).

     Outbreaks of encephalitis attributable to these viruses are
normally limited to specific geographic locations and seasons for
several reasons.  First, summer temperatures are normally
required for the viruses to multiply and to be transmitted to a
new host. Increased temperatures may quicken the transmission
process and promote epidemic disease.  However, the extent of
this effect depends largely on the particular virus.  Some
viruses require cooler weather and higher moisture conditions.
Thus, higher temperatures may reduce their prevalence.  Second,
environmental conditions that favor the presence of carriers and
hosts must prevail.  For example, relative humidity may affect
plant life necessary for the feeding of hosts.

Other Diseases

     A variety of other U.S. diseases indicate a sensitivity to
changes in weather.  Higher humidity may increase the incidence
and severity of fungal skin diseases (such as ringworm and
athlete's foot), and yeast infections (candidiasis).  Studies on
soldiers stationed in Vietnam during the war indicated that
outpatient visits for skin diseases (the largest single cause of
outpatient visits)  were directly correlated to increases in
humidity, but showed a 4-month lag with relationship to
temperature increases (Figure 14-10).  In addition,  excessively
high temperatures can lead to such skin diseases as prickly heat
and heat rash, which impair the ability of the skin to breathe
and thus place additional stress on people already suffering from
overexposure to heat from other causes.
                              14-25

-------
Chapter 14
                 2  600
                 N,

                 (fl
                    500 -
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                    300
                    200(4


                    100
A
                HUMIDITY -,
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                            JUNE

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                         600—86


                         500—84


                         400--i
                  -82


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200--
                                                                      0-^-74
                                       MONTH AND YEAR
                                 RAINFALL J

                          RELATIVE HUMIDITY	
                       Outpatient visits for skin digeatet in relation to mean monthly temperatitrt

                            index: U.S. Army pertonncl in Vietnam, 1967-TO
                       JAJOJAJOJAJOJAJO

                           1967        68         69          70

                                       MONTH AND YEAR




 Figure 14-10.   Relationship  of  Skin Infections to Humidity  and

                    Temperature.




 Source:    Longstreth  and Wiseman,  Volume  	.



                                       14-26

-------
Chapter 14
     Several diseases appear to be associated with the
acquisition of winter infections.  If a reduction in winter
severity is also accompanied by a decrease in wintertime
infections, these diseases could be reduced under global warming.

     For example, birth in cold winter months has been associated
with a higher risk of schizophrenia in individuals whose
schizophrenia is without an apparent genetic component (Kovelman
and Scheibel, 1983). In addition, juvenile-onset diabetes, which
has been reported to be increasing over the past several decades,
has been shown to be associated with a seasonal variation in that
the month of first admission peaks in the winter (Glatthaar et
al., 1988; Patterson et al., 1988).  It is a common clinical
experience that a minor viral illness precedes the onset of
symptoms.
NATIONAL IMPLICATIONS

     Human societies possess considerable ability to adapt to
change.  The potential for climate to affect human health may be
considerably modified by adaptive responses, such as
immunizations, modification of the environmental temperature
(e.g., use of air conditioners), and control of disease carriers.

     In addition, several demographic and technological trends
(the aging of the population, an influx of immigrants, advances
in treatment techniques) make it difficult to analyze the
potential impacts of climate change on human health.  Although
this chapter attempts to identify those human health effects at
risk from climate change, the analyses were not designed to
consider adaptive responses and should not be treated as absolute
predictions of what will happen with climate change.  Rather, the
analyses presented here represent possible scenarios in the
absence of consideration of demographic trends or adaptive
responses that may either exacerbate or ameliorate the impact of
climate change on human health.

     Climate change may affect regional and national health care.
For instance, the treatment requirements for asthma may increase
or decrease as locations experience changes in the distribution
and intensity of pollen concentrations.  Increased resources may
be needed to treat premature infants if there is an increase in
the number of preterm births.  If heart attacks, stroke, and
respiratory problems increase,  hospitalization costs and costs
due to days lost from work may also increase.  Higher health care
costs might be particularly obvious in Medicaid and Medicare
because those below the poverty line would be less able to take

                              14-27

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                                                     Human Health
adaptive measures (e.g., air-conditioning), and the elderly are
more susceptible to the ill effects of extreme weather
conditions.

     The United States is already dealing with an infant
mortality problem higher than that of any other industrialized
nation (World Bank,  1987).   Infant mortality is higher in the
summer; consequently, the increased temperatures expected with
global warming may well exacerbate the problem.

     The need for irrigation may increase in many regions of the
U.S. (see Chapter 10, Agriculture).  Irrigation may result in
greater amounts of standing water and can therefore increase
mosquito populations.  Arbovirus encephalitis may become a
greater problem than at present, and other mosquito-borne
diseases, such as dengue or yellow fever, could be more easily
spread if introduced.
POLICY IMPLICATIONS

     The full impacts of climate change on human health will
require more research.  Agencies such as the Department of Health
and Human Services should consider conducting studies a potential
impact.

     In the future a cadre of trained professionals may be needed
to respond to outbreaks of diseases.  A shift in the distribution
of carriers of human disease may necessitate regional shifts in
surveillance and eradication programs.  States that do not have
these programs may need to develop them in the future.


RESEARCH NEEDS

     One of the largest potential impacts of climate change
apparent in the literature is the increase in perinatal mortality
and preterm births.  An analysis similar to that performed by
Kalkstein, but focusing strictly on deaths in the 0- to 1-year
age group, might be warranted.  In addition, some refinements to
the Kalkstein analysis — e.g., focusing on the distinct causes
of death, and a more detailed analysis of the analogue modeling
results — are needed to provide additional insight into the
robustness of the conclusions from that study.
                              14-28

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Chapter 14
     The modeling that has been performed for vector-borne
diseases did not assess the potential impact of changes in the
host population (or habitat) that might result from climate
change.  Additional analyses are needed that evaluate what the
changes in host populations and habitat are likely to be and how
those changes could affect predictions from the ATSIM and MALSIM
models.
                              14-29

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                                                     Human Health
REFERENCES

APHA. 1985.  American Public Health Association.  In: Berenson,
A.S., ed. Control of Communicable Diseases in Man. Springfield,
VA: John D. Lucas Printing Company.

CDC. 1986. Centers for Disease Control.  Annual Summary 1984.
MMWR 33:54.

Cooperstock, M.,  and R.A. Wolfe. 1986.  Seasonality of preterm
birth in the collaborative perinatal project: demographic
factors. American Journal of Epidemiology 124:234-41.

Dukes-Dobos, F.,  1981. Hazards of heat exposure.  Scandinavian
Journal of Work and Environmental Health 73-83.

Gill, J.S., P. Davies, S.K. Gill, and D.G. Beevers. 1988.  Wind-
chill and the seasonal variation of cerebrovascular disease.
Journal of Clinical Epidemiology 41:225-230.

Glatthaar, C., P. Whittall, T. Welborn, M. Giboon, B. Brooks,
M.M. Ryan, and G. Byrne.  1988.  Diabetes in Western Australian
children:  descriptive epidemiology.  Medical Journal of
Australia, 148:117-123.

Glenzen, W.P. 1982.  Serious illness and mortality associated
with influenza epidemics.  Epidemiological Reviews 4:25-44.

Grant, L.D. 1988.  Health effects issues associated with regional
and global air pollution problems. Draft document prepared for
World Conference on the Changing Atmosphere, Toronto.

Haile, D.G. 1988.  Computer simulation of the effects of changes
in weather patterns on vector-borne disease transmission.  Report
prepared for U.S. EPA, Office of Policy, Planning and Evaluation.
U.S. EPA Project No. DW12932662-01-1.

Harris, R.E., F.E. Harrell, K.D. Patil, and R. Al-Rashid. 1987.
The seasonal risk of pediatric/juvenile acute lymphocytic
leukemia in the Unites States. Journal of Chronic Diseases
40:915-923.
                              14-30

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Chapter 14
Kalkstein, L.S., R.E. Davis, J.A. Skindlov, and K.M. Valimont.
1986.  The impact of human-induced climate warming upon human
mortality: a New York case study.  Proceedings of the
International Conference on Health and Environmental Effects of
Ozone Modification and Climate Change.  June 1986.  Washington,
DC.

Kalkstein, L.S.  1988.  The impact of C02 and trace gas-induced
climate change upon human mortality. Report prepared for the U.S.
EPA, Office of Policy, Planning and Evaluation.  U.S. EPA
contract No. CR81430101.

Kalkstein, L.S., and K.M. Valimont.  1987.  Effect on human
health. In: Tirpak, D., ed. Potential Effects of Future Climate
Changes on Forest and Vegetation, Agriculture, Water Resources,
and Human Health, Vol. V, pp. 122-152.  EPA 400/1-87/101E.
Washington, DC.

Keller, C.A., and R.P. Nugent.  1983. Seasonal patterns in
perinatal mortality and preterm delivery.  American Journal of
Epidemiology 118:689-98.

Kovelman, J. , and A. Scheibel.  1986.  Biological subtrates of
schizophrenia.  Acta Neurologica Scandinavica 73:1-32.

Kutschenreuter, P.H. 1959.  A study of the effect of weather on
mortality.  New York Academy of Sciences 22:126-138.

Lopez, M., and J.E. Salvaggio. 1983.  Climate-weather-air
pollution. In: Middleton, E., and C.E. Reed, eds.  Allergy,
Chapter 54.  St. Louis:  C.V. Mosby Company.

Mount, G.A., and D.G. Haile.  D.G. 1988.  Computer simulation of
population dynamics of the American dog tick, Dermacentor
variabilis (Acari: ixodidae). Journal of Medical Entomology.  In
Press.

Patterson, C., P. Smith, J. Webb, M. Heasman, and J. Mann. 1988.
Geographical variation in the incidence of diabetes mellitus in
Scottish children during the period 1977-1983.  Diabetic
Medicine, Vol. 5, pp. 160-165.

Rogot, E., and S.J. Padgett.  1976.  Associations of coronary and
stroke mortality with temperature and snowfall in selected areas
of the United States 1962-1966.   American Journal of Epidemiology
103:565-575.
                              14-31

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                                                     Human Health
i
Sontaniemi, E.,  U. Vuopala, E. Huhta, and J. Takkunem.  1970.
Effect of temperature on hospital admissions for myocardial
infarction in a subartic area.  British Medical Journal 4:150-1.

Vuori, I. 1987.   The heart and the cold.  Annals of Clinical
Research 19:156-162.

White, M.R., and I. Hertz-Picciotto.  1985.  Human health:
analysis of climate related to health. In: White, M.R., ed.
Characterization of Information Requirements for Studies of C02
Effects: Water Resources Agriculture, Fisheries, Forests, and
Human Health.  Department of Energy, DOE/ER/0236.

Wiseman, J., and J.D. Longstreth.  1988.  The potential impact of
climate change on patterns of infectious disease in the United
States.  Background paper and summary of a workshop.  Report to
USEPA Contract No. 68-10-7289.

World Bank.  1987.  World Development Report 1987.  New York:
Oxford University Press.
                              14-32

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                            CHAPTER 15

                       URBAN INFRASTRUCTURE

FINDINGS

Global climate change could require U.S. cities to make major
changes in capital investments and operating budgets.  Areas most
likely to be affected include water supplies, roads, and bridges,
storm sewers and flood control levees,  and energy demand in
municipal buildings and schools.

o    Most urban infrastructure in the United States will turn
     over in the next 35 to 5O years.  If changes in climate are
     considered, this turnover will allow cities to prepare for
     climate change at lower costs.  In some cases, the risk of
     climate change should be incorporated into decisions
     beginning today, such as coastal drainage systems that are
     likely to last for 5O to 1OO years.

Northern cities

o    Northern cities, such as Cleveland, may incur a change in
     the mix of their expenditures.  In such locations, increased
     electricity costs for air conditioning could be offset by
     reductions in expenditures for heating fuel,. snow and.ice
     control, and road maintenance.  Southern cities could see
     increases in operating budgets due to the demand for
     additional air conditioning.

Coastal Cities

o    Coastal cities may be subject to more severe impacts.  These
     include 12 of the 20 largest metropolitan areas.  For
     example:

          Sea level rise or more frequent droughts would increase
          the salinity of shallow coastal aquifers and tidal
          surface waters.  Cities that rely on water from these
          sources need to examine water supply options.  Such
          areas as Dade County, Florida, or New York City will
          probably be vulnerable.

     —   As sea level rises, some coastal cities would require
          levees to hold back the sea or fill to raise the land
          surface area.  In the case of Miami,  the cost of these
          activities might be more than $5OO million over the
          next 50 to 75 years.
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                                             Urban Infrastructure
Water Supply and Demand

o    Climate change will influence the supply and demand for
     water in many cities.   A lengthened summer season and higher
     temperatures will increase the use of water for air
     conditioners and lawns and gardens.  Changes in rainfall
     patterns, runoff, and flood control measures may alter water
     supplies.  In the Hudson River Basin, summer water demand
     could increase by 5 percent over the demand for water
     without climate change, while supplies might fall.  Such a
     change would require new institutional and management
     approaches for both the Delaware and Hudson Rivers.

Policy Implications

o    Climate change has implications for many national programs
     and policies.  For example:

     —   The National Flood Insurance Program may react to
          climate change by redrawing flood plain maps and
          adjusting insurance rates to account for sea level rise
          and changes in river flows.  It may be prudent to
          examine whether this program should anticipate climate
          change by discouraging development that would be
          vulnerable in the future.

          Because of the key role federal programs play in the
          development of cities, the Department of Housing and
          Urban Development should examine the implications of
          climate change on long-term policies.  A minimum
          response might be to provide guidance on the
          certainties and uncertainties of climate change to
          groups such as the National League of Cities, the U.S.
          Conference of Mayors, and the American Planning
          Association.

          Because water supply infrastructure may last for
          several centuries, improved planning is important.  The
          U.S. Geological Survey should study the probable
          impacts of global climate change and sea level rise on
          the water supplies of major cities.  The Corps of
          Engineers should factor climate change into the design
          of major projects.

          Given the assumption that modest changes in the design
          and location of many transportation systems may
          facilitate an accommodation to climate change, the
          Department of Transportation should factor climate

                               15-2

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Chapter 15
          change into the design of roads, bridges, and mass
          transit facilities.

          Voluntary standard organizations, such as the American
          Society of Civil Engineers, the Building Officials and
          Code Administrators, International and American Society
          of Heating and Refrigerating and Air Conditioning
          Engineers should examine the need for changes in
          existing standards to improve the use of energy and
          safety factors.
RELATIONSHIP BETWEEN URBAN INFRASTRUCTURE AND CLIMATE

     Three-quarters of the U.S. population is concentrated in
urban areas  (Statistical Abstract, 1987).  The majority of the
nation's investment in water supply, wastewater transport and
treatment facilities, drainage, roadways, airports, mass transit,
electric power, solid waste disposal sites, and public buildings
serves these urban areas. The current value of selected infra-
structure nationwide, displayed in Table 15-1, provides insight
into the aggregate investment at stake if climate changes.  Most
of these items could be considered part of urban infrastructure,
and have been located and designed based on historic meteorologic
information.

     Eighteen of the 20 most populated U.S. cities have access to
oceans, major lakes, or rivers* and have invested in additional
infrastructure for port facilities and flood control.  The
expenditure required to construct coastal defense structures —
which prevent inundation by the sea, slow oceanfront erosion,
control storm surges, slow saltwater advance up rivers, and
reduce saltwater intrusion into aquifers — is now minimal.

     Although actual practice varies, the nominal replacement
cycle for most infrastructure is 35 to 50 years (National Council
on Public Works Improvement, 1988).  Some water supply
investments have 100-year cycles.  Between planned replacement
      Of the 20 most populous cities in the U.S., twelve are tidal
waterfront cities (Baltimore, Boston,  Houston, Los Angeles, Miami,
New  York,   Philadelphia/Wilmington,   San  Francisco/Oakland,  San
Diego, Seattle,  Tampa/St.  Petersburg,  and Washington, D.C.), three
are located on the Great Lakes (Chicago,  Cleveland, and Detroit),
three are  on navigable rivers (Minneapolis,  Pittsburgh,  and St.
Louis) ,   and two  are  not  on  a  navigable  waterway  (Atlanta  and
Dallas).

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                                             Urban Infrastructure
TABLE 15-1. Value of the Nation's Stock of Selected Infrastruc
            ture (Billions of 1984 Dollars)


              Component                 Value3
            Water supply                $108
            Wastewater                   136
            Urban drainage                60
            Streets                      470
            Public airports               31
            Mass transit                  34
            Electric power               266
             (private only)6
            Public buildings          unknown
                    Total             $1,107+
aBased on a useful  life of  35  to  50  years  for most  assets,  and
 10 to 20 years for transit vehicles.
bAbout 77% of electric power is privately  produced.

 Source:  Statistical Abstract (1987);  National Council on           •
 Public Works Improvement (1988).


cycles; however, sea level rise,  temperature change, and changes
in precipitation patterns all  could alter the balance between
water supply and demand.  The  nature and pattern of precipitation
could affect drainage requirements as well as highway design and
maintenance.

     The heat wave of 1988 vividly illustrated some of the
potential impacts.   Hundred-degree weather distorted railroad
tracks, forcing Amtrack to cut speeds from 200 to 128 km per hour
between Washington and Philadelphia  (Bruske, 1988)  and possibly
causing a train wreck that injured 160 people on a Chicago-
Seattle run  (The Washington Post, 1988).   A U.S. Army Corps of
Engineers contractor worked around the clock for 2 weeks to build
a 170-m-wide, 9-m-high silt wall across the bottom 40% of the
Mississippi River channel,  48  km below New Orleans  (Sossaman,
1988a,b).  This $2 million wall,  designed to wash away when
spring snow melt demands the full capacity of the channel, slowed
an advancing wedge of saltwater that threatened the water supply
in New Orleans and nearby parishes.   In Manhattan,  heat
exacerbated the effects of long-standing leaks in 256 km of steam
pipes, causing the asphalt to  soften.  As vehicles kneaded the

                              15-4

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Chapter 15
soft asphalt, thousands of bumps formed on city streets,
requiring extensive repairs  (Hirsch, 1988).  In the suburbs of
Washington, D.C., steel expansion joints bubbled along a 21-km
stretch of Interstate 66  (Lewis, 1988).

     This chapter will examine such issues as the portions of the
infrastructure that will be significantly affected, and
anticipated costs and who will bear them.
PREVIOUS CLIMATE CHANGE STUDIES ON URBAN INFRASTRUCTURE

     Available literature on the potential effects of global
climate change on urban infrastructure is sparse.  Rhoads et al.
(1987) examined the potential impacts of sea level rise on water
supply and flood protection in Dade and Broward Counties,
Florida, and concluded that the effects might be severe.  Hull
and Titus (1986) analyzed the potential impact of sea level rise
on water supply in the Philadelphia-Wilmington-Trenton area, and
found that a rise of 0.3 m could require adding 140 million m3  of
reservoir capacity, about a 12% increase, to prevent saltwater
from advancing past water intakes on the Delaware River.
Additional investment would be required to prevent or respond to
saltwater infiltration into underground aquifers.

     Two recent studies illustrate the importance of considering
sea level rise in urban coastal infrastructure planning and the
uncertain nature of the decisions involved.  Wilcoxen (1986)
examined the impact of sea level rise on a portion of San
Francisco's sewage transport system that is buried close to the
shoreline.  The study estimated that if sea level rose 0.6 m by
the. year 2100, an expenditure of roughly $70 million on beach
nourishment might be required to prevent damage to a structure
that cost $100 million to build in the late 1970s.  The author
suggested that consideration (at no additional cost) of sea level
rise in siting the structure could have prevented these expenses.
Titus et al. (1987) examined the impact of sea level rise on a
proposed coastal drainage system in Charleston, South Carolina,
and estimated that a 0.3-m sea level rise by 2025 would require
almost $2.5 million in additional investments to maintain the
target level of flood protection.  The present value of these
investments is $730,000.  In contrast, only about $260,000, one-
third of the cost of responding in 2025,  would be required to add
this level of protection at initial construction.
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                                             Urban Infrastructure
URBAN INFRASTRUCTURE STUDIES IN THIS REPORT

     Several studies undertaken for this report examined some of
the implications of climate change in relationship to urban
infrastructure.  One study comprehensively examined the impacts
on infrastructure in several cities:

     o    Impact of Global Climate Change on Urban Infrastructure
          (Walker et al., The Urban Institute)

The following studies, referenced in this chapter, covered issues
relating to urban infrastructure:

     o    Electric Utilities (Linder et al., 1987)

     o    The Impacts of Low Lake Levels on the Illinois
          Shoreline  (Changnon, year)

     o    Case Studies of the Water Supply Systems of California
          and Atlanta, Georgia (Sheer, year)

     o    Defending Unprotected Shorelines  (Leatherman, year)

     o    Defending Protected Shorelines (Weggel, year)


RESULTS OF THE INFRASTRUCTURE STUDIES

Impacts on Miami/ Cleveland/ and New York City

     Walber et al. examined three cities distinctly affected by
climate change to determine a range of impacts on urban
infrastructure.

Study Design

     The study was based on a critical review of existing
infrastructure studies in the three cities, discussions of likely
impacts with local infrastructure experts,  analyses undertaken by
these experts, and preliminary calculations of probable impacts.
Experts were presented with GCM scenarios for C02 doubling,  and
scenarios were used to calculate effects on energy demand,
roadways, and other systems.  The study also derived conclusions
based on experiences in other cities where current temperatures
are analogous to temperatures projected for the cities under
study, using the analogues identified by Kalkstein (Vol.  ).
                               15-6

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Chapter 15
Limitations

     The principal limitation of the overall study is the limited
use of hydrologic and other modeling.  In addition, experts were
asked to derive conclusions regarding conditions beyond their
experience. Since only three cities are included, the full range
of effects on urban infrastructure was not covered.  The authors
did not perform engineering analyses of cost-effective responses,
and they did not assess the potential for reducing impacts
through technological change.

Results and Implications

     Miami's Infrastructure

     Greater Miami is bounded by water on all sides during the
rainy season.  An extensive network of canals and levees has been
built to control ocean and freshwater flooding and to recharge
the aquifer beneath the area.  Miami has one of the world's most
porous aquifers, which lies less than 1.5 m below the surface in
one-third of the developed area.  Federal law requires that
roughly-15% of Miami's freshwater be released into the Everglades
National Park.  The Dade County Development Master Plan predicts
that by 2000, a water supply deficit will force use of
desalinated water at three times current water costs.

     The Miami case study examined the probable impacts of
climate change and sea level rise on Dade County's water supply,
water control and drainage systems, building foundations, roads,
bridges, airports, solid waste disposal sites, and sewage
transport and treatment systems, assuming that a gradual sea
level rise would be managed through strategies such as raising
the land in low-lying areas, upgrading levees and dikes with
pumped outflows, retreat selectively from some areas, and
increasing the freshwater head roughly in proportion to sea level
rise to prevent saltwater infiltration into the aquifer.

     As Table 15-2 shows, global climate change could require
$500 million ($ \ billion),  in capital investment in Greater
Miami over the next century.  Because many systems could not be
estimated and because a complete engineering analysis was not
performed, these results should only be considered as rough
estimates.

     The south Florida aquifer is currently under pressure
because of growth in the Miami area.  Because the aquifer extends
under the ocean, the typical urban response to a rising sea —
diking the water at the surface and pumping out the seepage from

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                                             Urban Infrastructure
TABLE 15-2. Probable Infrastructure Needs and Investment in Miami
            in Response to a Doubling of C02 (Millions of 1987
            Dollars)
   Infrastructure Need
           Cost
Raising canals/levees
Canal control structures
Pumping
Raising streets

Raising yards and houses
Pumped sewer connections
Raising lots at reconstruction
Drainage
Airport
Raising bridges
Sewer pipe corrosion
Water supply

present
$60
$50
not
$250
cost
not
not
not
$200
$30
not
not
more
 at
estimated
 added to reconstruction

estimated
estimated
estimated
-300

estimated
estimated
 use of desalinated water
double
  water prices
Source:  Walker et al, Volume 	.
ditches behind the dikes — appears to be unworkable.  Unless the
dike extended down more than 45 m, rising seawater pressure would
cause the sea to rush into the aquifer below the surface and push
freshwater upward, almost to the surface.

     The one-time capital costs for upgrading existing canals and
levees in response to a 1-m sea level rise would be about $12
million.  However, almost $50 million in new control structures,
including extensive pumping capacity, might be required for the
canals used to maintain the freshwater head.  Large-scale pumping
for canvas also could involve substantial operating costs, but
these have not been estimated.  Storm sewers and drainage would
cycles; however, sea level rise, temperature change, and changes
in precipitation patterns all could alter the balance between
water supply and demand.  The nature and pattern of precipitation
need upgrading, requiring investment of several hundred million
dollars above normal replacement costs.
                               15-8

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Chapter 15
     Building foundations generally should remain stable if the
freshwater head rises 1 m because houses are built on concrete
slabs, most buildings in newer areas already are built on raised
lots to meet Dade County's flood control ordinance, and the
foundations of many larger buildings already extend into the
water table.

     Conversely, the water table could infiltrate the base of
about a third of Dade County streets, which would have to be
raised or risk collapse.  If sea level rose gradually, thereby
permitting raising of streets and related sewer mains during
scheduled reconstruction, the added public cost might be
approximately $250 million.  Building owners would incur
substantial costs to improve drainage, raise yards, raise lots at
reconstruction, and pump sewage to mains.  Miami's airport also
would need better drainage, requiring an approximate $30 million
investment.

     A 1-m rise in sea level would require raising most bridges
to ensure adequate clearances and reduce vulnerability to storm
surges during hurricanes.

     Global climate change could force Dade County to greatly
expand its planned use of desalinated water.  This may also be
needed by the Everglades National Park, if it is protected from
the rising sea.

     Analysis of Miami's coastal defense and water supply options
provides insight into the likely impacts of sea level rise on
cities built on coral reefs, but not into the likely response of
most mainland cities on the U.S. coastline.  Dade County is
unusual because readily extracted fill is extensively available
on public lands having easy access to a canal system that can be
navigated by flat-bottomed barges.  Nevertheless, this case study
suggests that global climate change could force large coastal
cities to invest billions of dollars to add and upgrade
infrastructure.

     Cleveland's Infrastructure

     The Cleveland case study examined impacts of climate change
on snow and ice control costs,  road construction and maintenance,
heating and cooling costs and equipment needs, water supply,  and
storm and wastewater transport.  The study also includes a
preliminary analysis of the effects of a drop in the level of
Lake Erie as estimated by Croley (see Great Lakes chapter of this
report).  The impact on the snow and ice control budget was
estimated by analogy to the budget in Nashville, Tennessee.

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                                             Urban Infrastructure
     Results are displayed in Table 15-3, which shows that the
net impact of climate change on Cleveland's annual infrastructure
costs could be negligible, although expenditures probably would
shift between categories.  In addition to the costs shown in
Table 15-3, a one-time capital expenditure of $68-80 million
could be required to add air-conditioners in public buildings.
Also, many private residences probably would install air-
conditioners .

     Walker et al. estimated that global climate change could
cause annual snowfall in Cleveland to drop from 1.25 to roughly
0.2 m, reducing annual snow and ice control costs by about $4.5
million.  Decreased frost damage to roads and bridges could yield
further savings estimated at $700,000 per year.  An estimated
drop of $2.3 million per year in heating costs for public
buildings also was projected.  Conversely, annual public air-
conditioning costs seemed likely to rise by $6.6-9.3 million.
The impacts on the transit operating budget seemed likely to
mirror the impacts on the general budget, with reduced mishaps
and traffic delays in ice and snow offsetting increased fuel
costs for vehicle cooling.

     The study suggested Cleveland might spend about $65-80
million to add air-conditioning to older schools and large
nonoffice spaces such as gyms and repair garages.  Much of this
expenditure would occur as buildings were replaced or refurbished
and might have occurred even without climate change.
     The rise in winter temperatures associated with a doubling
of C02 might allow Cleveland  to  use  thinner  pavement resulting in
possible savings of about 3% in road resurfacing costs and 1% in
reconstruction costs.  The net savings could average about
$200,000 per year or 1.3% of the city's current capital budget.
Standard engineering 'estimates  (AASHTO, 1987) suggested that the
rate of pavement deterioration probably also should decline as
winter temperatures rise, saving roughly $500,000 per year.

     A climate-induced drop in the level of Lake Erie probably
would not adversely affect Cleveland, although some dredging
might be required in the Cuyahoga River.  Upgrading of the city's
combined storm and wastewater collection system appeared to be
unnecessary, although this would depend upon rainfall
variability.
                                                                     I
                              15-10

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Chapter 15
TABLE 15-3. Estimated Impacts of a Doubling of CO2 on Cleveland's
            Annual Infrastructure Costs  (Millions of 1987
            Dollars)
          Cost Category
    Annual
Operating Costs
          Heating
          Air-conditioning
          Snow and ice control
          Frost damage to
           roads
          Road maintenance
          Road reconstruction
          Mass transit

          River dredging
          Water supply
          Storm water system

               Total
     -$2.3
     +$6.6-9.3
     -$4.5

     -$0.7
     -$0.5
     -$0.2
summer increase offsets
 winter savings
less than $0.5
negligible
negligible
-$1.6 to +$1.1
Source:   Walker et al.  (Volume 	); Weggel et al.  (Volume).
     If temperature rises several degrees, most northern cities
probably could anticipate savings in snow and ice control,
heating, and roadway construction and maintenance costs similar
to those described for Cleveland.  These savings might
approximately offset the increase in air-conditioning costs.
Communities south of Cleveland probably would experience modest
budget increases.  Cleveland could become a more attractive
location for water-intensive industry if water supplies in other
areas become less reliable.  Resulting in-migration could bring
further growth-related infrastructure costs. (See Great Lakes
chapter for a further discussion of this issue.)

     New York City's Water Supply

     New York City's infrastructure may be affected in many ways
by global climate change.  Temperature change could affect the
same capital expense categories in both New York City and
Cleveland.  In addition,  the city may have to invest heavily to
protect underground infrastructure from seawater infiltration.

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                                             Urban Infrastructure
The most pressing, and perhaps largest, problem facing the city
may be the effects of global climate change on the-adequacy of
the city's water supply.  The New York City study focused on that
issue.

     The New York metropolitan area draws water from the
adjoining Hudson and Delaware River Basins and from underground
aquifers serving coastal New Jersey and Long Island.  Figure 15-1
shows the region and its water supply sources.

     The water supply network is in deficit.  The Mayor's Task
Force (1987) has recommended remedying New York City's portion of
the deficit through better management of water demand and
detailed study of the possibility of reactivation of a water
intake at Chelsea, a $223-391 million investment that would yield
375 to 750 million liters of water daily.

     Walker et al. estimated changes in water demand using design
standards for commercial cooling-tower demand, changes in
electricity demand estimated by Linder et al. (1987),  historic
residential summer water use, and estimates by Hull and Titus
(1986) of saltwater advance up the Delaware River.  This last
estimate is an order-of-magnitude estimate made by analogy.
Water supply was also estimated by analogy, using a Great Lakes
water balance model.  Walker et al. assumed that baseline demand
would not increase above projected demand in 2030, potentially
underestimating the increased demand for water and saltwater
advance.

     Walker et al. also estimated that a rise in temperatures
consistent with the GISS and GFDL scenarios would mean about a
20% increase in cooling degree days.*   In response,  average daily
demand for water used in cooling large buildings could increase
by 190 million liters during the summer and increased lawn
watering could raise demand by 110 million liters per day,
thereby generating a 5% rise in annual demand.

     Higher temperatures could increase evaporation and
evapotranspiration, decreasing the ability to store water
efficiently in surface impoundments.  The water balance model
indicated the supply loss could range from 10 to 24%.
     *The number of degrees by which the average daily temperature
exceeds 65°F.

                              15-12

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Chapter 15
                                                      MASSACHUSt TT 5
                                         CATSKILL WATERSHED
                                           »
                                           >    (s
                                          Kingston
                                                     CONNECTICUT
                                                CROTON
                                              ^WATERSHED
                                              JAMAICA NYC
                                              WELLFIELD
                                             «• Limlti of the Hudson gnd Dtltware
                                               River Hums
                                               Hew York City Supply Water thedi
                                               Htw Croton Aqueduct
                                               Cittklll Aqueduct
                                               Delfwtre Aqueduct
                                           o    20    *0    « wins
Figure 15-1.    The Sources of New York City's  Water  Supply.
Source:  Citizen's Union  Foundation of the City of New York,
          1986.
                                  15-13

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                                             Urban Infrastructure
     Saltwater infiltration due to rising sea level would further
reduce supply.  The study suggested that a 1-m sea level rise
could place the proposed $300 million Chelsea intake below the
salt line during the peak summer demand period in mild drought
years, reducing supply another 13%.  Larger sea level rise or
greater droughts might prevent use of the existing Poughkeepsie
intake during severe droughts, further reducing supply.  In
addition, subsurface infiltration could reduce the supply
available from the Long Island aquifer.

     In summary, doubled C02 could produce a  shortfall  equal  to
28 to 42% of planned supply in the Hudson River Basin.

Implications Arising From Other EPA Studies in This Report

     Linder (1987),  in analyzing national electricity demand (see
Electricity Demand chapter of this report), suggests that
increased air-conditioning use could raise peak electricity
demand by 10 to 20% in New York and by 20% in the Southeast.
Nationally, the northernmost areas would experience decreased
demand, and the remainder of the country would experience
electricity needs higher than currently estimated.  Sheer's study
of California (see Chapter 4) water supply suggests that new
surface water impoundments may be needed to meet urban water and
other demands.  The coastal defense strategies suggested in the
Sea Level Rise chapter (Chapter 9) would apply to most urban
coastal areas, especially those along the Atlantic and Gulf
coasts.
RESULTS OF RELATED STUDIES

Metropolitan Water Supply

     Schwarz and Dillard (1988)  conducted telephone interviews
with local infrastructure managers to identify the probable
impacts of global climate change on water supply and drainage in
several metropolitan areas.  Results from some cities are
discussed here.

Washington. DC

     Longer hot spells could warm the Potomac River and cause
trihalomethane formed during chlorination to rise above allowable
limits.  Remedying this could require a capital investment of
roughly $50-70 million and could increase treatment costs.  Also,
lawn watering probably would increase during long spells of hot,
dry weather.  Although a substantial decrease in runoff could

                              15-14

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Chapter 15
reduce supply in parts of the system, the availability of
additional storage capacity would make a shortage unlikely.

New Orleans

     Sea level rise could necessitate moving the water intakes
considerably farther up the Mississippi and replacing cast iron
water mains that would corrode if exposed to salt water.  Reduced
river flow also could increase settling and treatment require-
ments.  Rising sea level could increase saltwater infiltration
into the water system and could require increased pumping
capacity.

New York City

     This study raised many of the same concerns regarding water
supply and demand as the study by Walker et al. (Vol. X) and
indicated that even a 0.25-m sea level rise would mean the
proposed Chelsea intake was too far downstream.  The sanitary and
storm sewage system capacity and design probably would not need
revision.  Nevertheless, in a few low-lying areas, higher sea
level could increase sewer backups, ponding, and basement
flooding when high tides coincided with high runoffs.

Tucson

     Tucson is depleting its aquifer despite substantial
conservation efforts and lawn watering with treated wastewater.
Higher temperatures would increase demand and tighten supply,
possibly jeopardizing the city's ability to draw on water from
the Central Arizona Project on the already strained Colorado
River.  While modest savings might be achieved through stricter
conservation measures and more wastewater use, purchase of water
in the regional market most likely would be the only practical
response to climate-related shortfalls.
IMPLICATIONS FOR THE NATION'S URBAN INFRASTRUCTURE

     The implications of climate change for urban America vary
spatially.  Some localities, especially those along the Great
Lakes, might benefit.  Others, especially those along the
coastlines and in water-short areas, could face major
infrastructure costs. The costs would be especially high if
changes came through abrupt "sawtooth" shifts, making it
difficult to adapt infrastructure primarily during normal repair
and replacement.  The likely impacts of an effective doubling of
atmospheric C02 could affect a wide  range  of  infrastructure.

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                                             Urban Infrastructure
Water

     Hotter temperatures could cause faster evaporation of
groundwater and raise the demand for water to support commercial
air-conditioning systems and lawn watering.  Larger winter rains
in the West could force a lowering of dam levels to ensure
availability of enough capacity to control flood waters.
At the same time, sea level rise could cause saltwater to advance
up rivers and to infiltrate into coastal aquifers.  In droughts,
many existing water intakes might deliver brackish water.

     The solution to these problems could be expensive:  strong
conservation measures, miles of aqueducts from new water intakes
at higher river elevations, new reservoirs, sewage effluent
recycling systems to support commercial cooling or lawn watering,
and perhaps desalinization efforts along the coasts.  The
solution for the New York-Philadelphia corridor alone is likely
to cost $3-7 billion.  Communities in the Delaware River Basin,
northern New Jersey, the lower Hudson, and Long Island might well
form a multi-State water supply and management district of
unprecedented size and complexity to handle financing and capital
construction.

Drainage and Wastewater Systems

     Increased storm size and intensity could tax many storm
sewer systems.  Sea level rise also could reduce coastal flood
protection levels in low-lying areas.  The resulting increases in
flooding and releases of untreated waste into watercourses from
combined storm and wastewater systems probably would motivate new
sewer investments.  In Bade County alone, costs to maintain flood
protection at existing levels could be $200-300 million if sea
level rose 1 m.

     Temperature rise could increase hydrogen sulfide formation
in sewer pipes, leading to internal corrosion and eventual
failure.  In coastal areas, increased ocean flooding could
increase how frequently storm sewers must carry corrosive
saltwater.  Sea level rise also could cause more pipes in coastal
areas to face the external risk of corrosive seawater.  More
frequent inspection and earlier replacement of much existing
pipe, as well as a gradual shift to more corrosion-resistant pipe
with plastic lining, might be required.

Coastal Defenses

     Protection from a rising sea could require tremendous
investment in many major coastal communities.  In urban areas, a

                              15-16

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Chapter 15
common approach might be the New Orleans solution, where
extensively developed coastal areas are protected by dikes, and
covered drainage ditches behind the dikes are pumped to keep out
the saltwater.

Roads

     Rising temperatures could reduce the costs of road
construction and maintenance.  Snow and ice control costs might
drop dramatically.  A decrease in deep freezes and freeze-thaw
cycles also would mean fewer potholes.  Warmer temperatures and
the improved drainage resulting from higher evaporation rates
could permit use of thinner pavements in many areas, but require
enhanced expansion capabilities.

Bridges

     Sea level rise and increased storm intensity could require
upgrading of many bridges either through costly retrofit or as
part of normal reconstruction.  The range of temperature
accommodated by expansion joints also might need to be increased.
The costs might be modest if bridge planners upgraded in
anticipation of climate change.

Mass Transit

     In the North, buses and railcars could experience fewer
snow-related delays.  Conversely, slight increases in fuel costs
could result from increased use of air-conditioners.

Electricity and Air-Conditioning

     Hotter temperatures could increase air-conditioning use.
Consequently, peak load capacity tp generate electric power might
have to increase in response to global climate change.
Fortunately, air-conditioning equipment is replaced fairly
frequently, so increased loads on existing equipment could be
accommodated incrementally.   Some houses and public buildings in
northern climates might need to add air-conditioning, but such
retrofitting has been performed since the first window air-
conditioners were introduced.
NATIONAL POLICY IMPLICATIONS

     The uncertain, yet potentially imminent, impact of global
climate change has already increased the risks of infrastructure
investment.  Application of design standards and extrapolation

                              15-17

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                                             Urban Infrastructure
from historical data still may not provide reasonable assurance
that water and power supply, dam strength and capacity, bridge
clearances, or storm sewerage capacity will be adequate for the
35-, 50-, and 100-year design cycles of these facilities.  For
example, the National Flood Insurance Program's maps identifying
the historical 100-year floodplain and 500-year floodway may no
longer provide a reliable basis for local building and zoning
ordinances designed to minimize flood losses to life and pro-
perty .

Investment Analysis Methods

     Especially in coastal areas, the possibility of accelerating
global climate change may soon require careful decisions
regarding how and when to adapt the infrastructure.   A strong
emphasis on life-cycle costing and upgrading during
reconstruction in anticipation of future changes could yield
large, long-term cost savings.  To accomplish this goal such
institutions as the Department of Housing might work with the
American Public Works Association, the National League of Cities,
the U.S. Conference of Mayors, the American Planning Association,
and similar groups to educate their constituencies regarding the
uncertainties and ways to incorporate them into the
decisionmaking process.

Water Supply

     Water supply is of particular concern because decades are
required to plan and complete projects, which then might last 100
years.  Dams, reservoirs, and water intakes currently being
planned and built could become obsolete or inadequate as a result
of global climate change.  Elsewhere, communities might be
allowing development of land needed for reservoirs to meet the
water shortages that would result from climate change.

     Such federal agencies as the U.S. Geological Survey, U.S.
Army Corps of Engineers, and EPA may wish to work with States and
municipalities to study the probable impacts of climate change
scenarios on the water supply of major metropolitan areas.

     Water supply investments frequently affect multi-State
areas, creating a need for Federal coordination.  The Supreme
Court has been forced to settle previous water rights disputes
concerning many major rivers, and global climate change might
well generate new disputes.  Cost-effective response to climate
change also might require new multi-State water projects.  For
example, a major project on the Hudson River that allowed New
York City to reduce its use of Delaware River water might be the

                              15-18

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Chapter 15
least costly way to increase water supply in Philadelphia.  The
upcoming State debates over water supply financing should be
informed by the lesson of past infrastructure crises:  water
piping and pumping costs resulting from global climate change
should be fully recovered from the water users to avoid stimulat-
ing artificial demand for bargain water.

Infrastructure Standards

     Voluntary standards organizations, such as the American
Society of Civil Engineers, the Building Officials and Code
Administrators International, and the American Association of
State Highway and Transportation Officials, may wish to educate
their committees on global climate change.  Growing uncertainty
concerning future temperature, precipitation, and sea levels
might dictate a reassessment of existing standards and safety
factors for ventilation, drainage, flood protection, facility
siting, thermal tolerances, resistance to corrosion, and so
forth.  Conversely, prompt detection of lasting changes could
allow adjustment of geographically based standards — for
example, on roadbed depth and home insulation levels — and
provide significant savings.  Thus, the standard-making organiza-
tions might beneficially establish policies concerning how and
when their committees should account for global climate change or
educate their committees about the prospects.

     Voluntary standard organizations, such as the American
Society of Civil Engineers, the Building Officials and Code
Administrators, International and American Society of Heating and
Refrigerating and Air Conditioning Engineers should examine the
need for changes in existing standards to improve the use of
energy and safety factors.
                              15-19

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                                             Urban Infrastructure
BIBLIOGRAPHY

AASHTO.  1987.  American Association of State Highway and
Transportation Officials.  Manual for the Design of Permanent
Structures, Appendix A.  Treatment of Roadbed Swelling and/or
Frost Heave in Design.

Bruske, E.  1988.  104 (phew!) degrees hottest in 52 years.  The
Washington Post 111(225):A1, A6.  July 17.

Hirsch, J.  1988.  As streets melt, cars are flummoxed by
hummocks.  The New York Times 137(47599):B1, B5.  August 16.

Hull, C.H.J., and J.G. Titus, ed.  1986.  Greenhouse Effect, Sea
Level Rise, and Salinity in the Delaware Estuary.  Washington,
DC: U.S. Environmental Protection Agency.   Publication no. 230-
05-86-010.

Lewis, N.  1988.  Two more heat records fall as summer of 1988
boils on.  The Washington Post 111 (257):A1, A10, All.  August
18.

Linder, K.P., M.J. Gibbs, and M.R.  Inglis.  ICF Incorporated.
1987.  Potential Impacts of Global Climate Change on Electric
Utilities.  New York State Energy Research and Development
Authority, Albany, NY.  Publication no. 824-CON-AEP-86.

Mayor's Intergovernmental Task Force on New York City Water
Supply Needs, "Managing for the Present, Planning for the
Future", December 1987.

Metropolitan Dade County Planning Department. 1987. Comprehensive
Development Master Plan for Metropolitan Dade County, Florida.
July 1979, Amended July 1985 and June 1987.

National Council on Public Works Improvement.  1988.  Fragile
Foundations - Final Report to the President and Congress,
Washington, DC.  February 1988.

Rhoads, P.B., G.C. Shih,  and R.L. Hamrick.  1987.  Water resource
planning concerns and changing climate:  A Florida perspective.
In:  Proceedings of the Symposium on Climate Change in the
Southern United States:  Future Impacts and Present Policy
Issues.  Norman:  University of Oklahoma,  pp. 348-363.
                              15-20

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Chapter 15
Schwarz,.H.E., and L. Dillard.  1988.   (Draft Report) Urban
water. Chapter III-D.  In:  AAAS Global Climate Change Report.
Washington, DC.

Sossaman, B.A.  1988a.  News Release, U.S. Army Corps of
Engineers, New Orleans District.  June 28.

Sossaman, B.A.  1988b.  News Release, U.S. Army Corps of
Engineers, New Orleans District.  July 15.

Statistical Abstract of the United States - 1987, U.S. Government
Printing Office, 1988.

Titus, J.G., C.Y. Kuo, M.J. Gibbs, T.B. LaRoche, M.K. Webb, and
J.O. Waddell.  1987.  Greenhouse effect, sea level rise, and
coastal drainage systems.  Journal of Water Resources Planning
and Management 113(2):216-227.

The Washington Post.  1988.  Warped rails checked in Amtrak
wreck.  111(246):A5.  August 7.

Wilcoxen, P.J.  1986.  Coastal erosion and sea level rise:
Implications for ocean beach and San Francisco's westside
transport project.  Coastal Zone Management Journal 14(3):173-
191.
                              15-21

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                            CHAPTER 16

                NATIONAL IMPACTS  OF CLIMATE  CHANGE
                      ON ELECTRIC UTILITIES
FINDINGS

Global warming would increase; electricity demand, generating
capacity requirements, annual! generation, and fuel costs.  The
impacts could be significant within a few decades, and would
increase substantially over time if global warming continues.

o    By 2010, new generating capacity requirements induced by
     climate change are estimated to increase by 25 to 55
     gigawatts (GW) or 9 to 19 percent above estimated new
     capacity requirements, assuming no change in climate.
     Between 2010 and 2055, climate change impacts could
     accelerate,  increasing new capacity additions by 200 to 400
     GW (14 to 23 percent) above what would be needed in the
     absence of climate change.  These capacity increases would
     require investments of approximately $200 to $300 billion.
     These results are sensitive to assumptions about the rates
     of economic growth, technological improvements, and the
     relationship between energy use and climate.  The savings in
     other fuels (gas and oil)  in northern regions and the
     impacts on hydroelectric supplies were not analyzed.

o    Estimated increases in annual electricity generation and
     fuel use induced by climate change represent several
     thousand gigawatt-hours by 2055.  The estimated increases
     are l to 2 percent in 2010 and 4 to 6 percent in 2055.
     Annual fuel, operation, and maintenance cost would be
     hundreds of millions of dollars in 2010 and several billion
     dollars in 2055.

o    Estimated regional impacts differ substantially for the
     scenarios studied.  The largest increases would occur in the
     Southeast and Southwest,  where air conditioning costs are
     large relative to heating.  Northern border states may have
     a net reduction in electricity generation relative to base
     over increases in generation capacity.

Policy Implications

o    Utility executives and planners should begin to consider
     climate change as a factor in planning new capacity.  The
     estimated impacts of climate change is similar to other
     uncertainties and issues utility planners may need to
     consider over the 20-30 year period.  Additional climate and
                               16-1

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Chapter 16
     utility analyses are needed to develop refined risk
     assessments and risk management strategies.

     The increased demand for electricity induced by climate
     change also could offset other environmental problems, such
     as the implementation of "acid rain" strategies, adherence
     to the international NOX treaty,  state  implementation plans
     for ozone control, and thermal pollution control permit
     requirements.  The Environmental Protection Agency should
     analyze the impacts of climate change on long-range policies
     and should include climate change as an explicit criterion
     in making risk management decisions when appropriate.

     The increased demand for electricity could make policies to
     stabilize the atmosphere through energy conservation more
     difficult to achieve.  The estimated increases in
     electricity generation induced by climate change alone could
     increase annual C02 emissions  by  40-65  million tons in 2010
     and by 250-500 million tons in 2055.  This does not consider
     reduced demand for oil and gas in residential furnaces for
     heating.  Future analyses of national and international
     strategies to limit greenhouse gases should include the
     additional energy demand created by global warming as a
     positive feedback.
CLIMATE CHANGE AND ELECTRICITY DEMAND

     While climate change could affect a wide range of energy
sources and uses, its implications with regard to the demand and
production of electricity could be significant.  Many electrical
end uses vary with weather conditions.  The principal weather-
sensitive end uses are space heating and cooling and,, to a lesser
degree, water heating, cooking, and refrigeration.  These
applications of electricity may account for up to a third of
total sales for some utilities and may contribute an even larger
portion of seasonal and daily peak demands.  (Electric energy
used for air-conditioning exceeds that used for space heating
nationwide, and the temperature-sensitivity associated with
cooling is higher than that associated with heating.)

     Changes in weather-sensitive demands for electricity can
affect both the amount and the characteristics of generating
capacity that a utility must build and maintain to ensure
reliable customer service.  These changes also can affect fuel
requirements and the characteristics of efficient utility system
operations, particularly the scheduling and dispatching of the
utility's generating capacity.

                               16-2

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                                                           Energy
     Similarly, utilities in most regions experience their peak
demands in the summer.  A rise in air-conditioning and other
temperature-sensitive summer loads could significantly increase
peak loads and, as a result, would step up utility investments in
new generating capacity needed to meet additional demands and to
maintain system reliability.
PREVIOUS CLIMATE CHANGE STUDIES

     A number of utilities conduct analyses relating short-term
variations in weather conditions with a need to "weather-
normalize" historical demand data and to test the sensitivity of
system reliability and operations to these short-term variations.
Furthermore, some researchers have speculated regarding the
potential effects of longer term climate changes on electricity
demand (e.g., Stokoe et al., 1987).

     However, only one previous study has estimated the potential
implications of longer term, global warming-associated
temperature changes on electricity demands and on utility
investment and operating plans.  Linder et al. (1987) used
General Circulation Model (GCM) results to estimate the potential
impacts of temperature change on electricity demand and on the
supply of hydropower for selected case study utility systems in
two geographical areas: a utility located in the southeastern
United States and the major utilities in New York State,
disaggregated into upstate and downstate systems.

     Linder et al. found that temperature increase could
significantly heighten annual and peak electricity demands by
2015, and that a temperature rise would require construction of
new generating capacity and increases in annual generation.
The southeastern utility had higher estimated increases in
electricity demand, generation, and production costs than the New
York utilities because of greater electricity demands for air-
conditioning.  In addition,  streamflow used to generate
hydropower in New York could be reduced, requiring increased use
of fossil fuel generation to meet customer demands for
electricity.
                               16-3

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Chapter 16



CLIMATE CHANGE STUDY IN THIS REPORT

Study Design

     Linder and Inglis1  expanded on the  regional  case studies of
the sensitivity of electricity demand to climate change by
conducting a national analysis of electricity demand.  The
national analysis used the same basic approach as that used in
the regional case studies.  Relevant regional results from
Linder's national studies are discussed in the regional chapters
of this report.

     The analytic approach developed by Linder et al. formed the
basis for estimating the regional and national impacts described
in this report.  The principal steps in the approach are
summarized in Figure 16-1 (see Volume X for more details).
Estimated impacts were developed for the relatively near term
(from the present to 2010, within electric utility long-range
resource planning horizons of 20-30 years) and over the longer
term (to 2055), when the magnitude of temperature changes is
expected to approach equilibrium levels representative of a
doubling of atmospheric concentrations of CO2.  Linder and Inglis
used Goddard Institute for Space Studies  (GISS)  A and B transient
estimates of temperature change in 2010 and 2055 in his
calculations.  The changes in annual temperatures for the utility
regions ranged from about 0.6 to 1.6°C in 2010 and from about 3.1
to 5.3°C by 2055.

     Linder and Inglis used actual utility demand and temperature
data from the case study utilities, and from five other large,
geographically dispersed utility systems to develop a set of
weather-sensitivity parameters for utility areas. Pn a weighted-
average basis (weighted by electricity sales), utility peak
demands were estimated to increase by about 3.1% per change in
degree Celsius (ranging from -1.35 to 5.40% across utility
areas),  and annual energy demands were estimated to increase by
about 1.0% per change in degree Celsius (ranging from -0.54 to
2.70%).

     A number of uncertainties associated with the data and
assumptions used to develop these weather-sensitivity
relationships suggested that the relationships may understate
customer response to climate change, particularly at higher ,
     1The Potential Impact of Climate Change on Electric Utilities:
Regional and National Estimates — Linder and Inglis, ICF, Inc.
                               16-4

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Chapter 16
temperature change levels occurring in the future.  For example
the approach did not explicitly account for probable increases in
the market saturation of air-conditioning equipment as
temperatures rise over time.  To address this possibility, an
alternate case was designed in which the estimated weather-
sensitivity values were increased by 50%.  This was designated as
the "higher sensitivity" case.

     Since this study is focused on estimating how climate change
may affect key utility planning factors, Linder used a planning
scenario assuming no change in climate (3 "base case") to serveas
a basis for comparison with planning scenarios under alternative
assumptions of climate change for 2010 and 2055.  Thus, base case
utility plans .were developed for 2010 and 2055, using assumptions
regarding future demands for electricity in the absence of
climate change, generating technology option performance and
costs, fuel costs, and other utility characteristics.  Linder and
Inglis assumed that future capacity and generation requirements
will be met by investments either in new coal-fired baseload
capacity or in oil- and natural gas-fired peaking capacity.
Other sources, such as nuclear energy and renewables or
innovative fossil fuel-fired technologies (e.g., fluidized bed
combustion) were not considered.

     Demands for electricity in the absence of climate change can
be related to the overall level of economic activity as
represented by the gross national product (GNP).  Because of the
critical nature of economic growth, alternative GNP growth rates
were assumed in developing the base cases; these ranged from 1.2
to 2.1% per year.**  These alternative assumptions are referred
to as "lower growth11 and "higher growth," respectively.

     These assumptions served as inputs to a regional planning
model called the Coal and Electric Utilities Model (CEUM).  CEUM
output includes the amount and characteristics of new generating
capacity additions, electricity generation by fuel type, and
electricity production costs.
     'innovative technologies will penetrate future power markets.
However,  the  analysis  for this  focused  on  distinction  between
requirements for peaking capacity vs. baseload capacity generally
and not on utility investments in specific types of technologies.

     **These GNP growth rates are  relatively conservative, but they
are comparable with GNP growth rates used by EPA in its Report to
Congress on atmospheric stabilization.

                               16-6

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                                                           Energy
Limitations

     The study did not include analysis of temperature
sensitivity for all utility regions of the United States.  It
focused narrowly on impact pathways, considering only the
potential effects of temperature change on changes in electricity
demand.  Neither the potentially significant impacts of climate
change on hydropower availability nor the impacts of reduced
water supplies for cooling were included.

     Furthermore, the study did not evaluate the sensitivity of
the results to different GCM climate scenarios, although the use
of the GISS transient experiment results for 2010 and 2055
indicates relative sensitivities to small and large temperature
changes.

     Very limited climate change information important for
utility planning was available (e.g., variations in temperature
changes and the occurrence of extreme events, which affect
powerplant dispatch and determinations of peak demands,
respectively).

     Many uncertainties exist regarding the concepts, methods,
and assumptions involved in developing and applying estimates of
the temperature sensitivity of demand.  For example, a key
assumption is that the estimated sensitivities of demand to
historical, short-term variations in temperature are adequate
representations of future relationships between electricity
demand and long-term changes in mean temperatures.

     Uncertainties also exist regarding market, regulatory,
technological, and other conditions that will face the utility
industry in the future.  For example, technological changes that
improve the energy efficiency of weather-sensitive end-use
equipment or electricity-generating equipment could reduce the
estimated impacts of climate change.

Results

     The potential national impacts for 2010 and 2055 are
summarized in Table 16-1.  The table presents base case values
(i.e.,  assuming no change in climate) for each year and estimated
impacts represented by changes from the base case values.  The
impacts for 2055 are presented for both the lower growth GNP and
the higher growth GNP cases.  Also, where ranges of impacts are
presented,  they summarize the estimates under alternative climate
change scenarios (GISS A and GISS B) and assumptions of the
                               16-7

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        Chapter 16
TABLE 16-1.   The Potential National Impacts  of  Climate  Change on Electric
              Utilities
                             2010
                        Base  Increase
                                                          2055
                                                Lower GNP        Higher GNP
                                             Base  Increase  Base   Increase
Peak demand (GW)
                         774
New capacity reqirements (GW)
  Peaking                 50

  Baseload               226

  Total                   376"

Annual sales (bkWh)    3,847

Annual generation13 (bkWh)
  Oil/gas                287
  Coal                 2,798
  Other                 1,092
  Total
                       4,177
Cumulative capital       669
costsc  (billions of 1986  $)
Annual costs (billions
 of 1986 $)
                         162
20-44


13-33

11-22

24-55

39-67
54-103
 1- (1)

43- 72

 25-48



 3-6
1,355   181



  176   118

1,011    67
                 474
                                              1,187   185

                                              6,732   281
                                                221     2
                                              6,242   305
                                                846   (2)
               7,309   305

               1,765   173
         33
1,780  238-357



  254  182-286

1,423   74- 98
                1,677  227-384

                8,848
                                 308    27-  51
                               8,295   381-560
                               1,003   (7)-   0
                9,607  401-611

                2,650  222-328
  655
48-73
alncludes  reserve margin requirements;  does not include "firm scheduled"
capacity.
blncludes  transmission and distribution losses.
c"Base"  values include regional capital expenditures for utility-related
equipment in addition to new generating capacity  (e.g., new  transmission
facilities).

Abbreviations:  GW = gigawatts; bkWh = billion kilowatthours.
Source:   Linder and Inglis, Volume 	.
                                      16-8

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                                                           Energy
weather sensitivity of demand  ("estimated sensitivity" and
"higher sensitivity").

     Estimated increases in peak demand on a national basis range
from 2 to 6% by 2010.  Changes in estimated annual energy
requirements by 2010  are more modest, ranging from 1 to 2%.  In
2055, peak national demands are estimated to increase by 13 to
20% above base case values, and annual energy requirements are
estimated to increase by 4 to 6%.  By 2010, new climate change-
induced generating capacity requirements increase by 6 to 19%, or
about 24 to 55 GW, representing an average increase of up to 1 GW
per State (approximately the capacity of a large nuclear or coal-
fired baseload powerplant).  The majority of the capacity
increase is for peaking capacity rather than baseload capacity.
The investment associated with these capacity increases is
several
billion dollars (in constant 1986 dollars).  By 2055, the change
in new capacity requirements increases in percentage terms and
represents several hundred GW.  Under high GNP and higher
weather-sensitivity assumptions, the estimated increase
attributable to climate change is almost 400 GW, or 23%.

     Annual generation increases for the United States are not as
large in percentage terms as those estimated for new generating
capacity requirements, but nonetheless, they account for several
hundred billion kWh by 2055.  In the near term (i.e., to 2010),
increased levels and changing patterns of climate change-induced
electricity demand permit utilities in some areas having
excess generating capacity to serve the growing needs of
utilities in other areas through substitution of lower cost coal-
fired generation for higher cost oil- and natural gas-fired
generation.   On net, oil- and gas-fired generation would be lower
owing to climate change in 2010.*  In 2055,  oil-  and  gas-fired
generation is projected to increase along with coal-fired
generation,  because all the excess capacity that had existed in
2010 either would have been fully used by growing demands to 2055
or would have been retired.  The estimated impacts of climate
change on national new generating capacity requirements and
annual generation are illustrated in Figure 16-2.

     Table 16-1 also indicates that the increase in annual costs
for capital,  fuel, and O&M associated with climate change-induced
modifications in utility investments and operations are a few
      This  result  is confirmed and explained in more detail in the
case study report (Linder et al., 1987).

                              16-9

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       2200
       2000  —
       !*OO  —
    VI
    «<
    **
    «
    £
    (8
    2
    o
       1000  —
               New Capacity Requirements
                                                                   —  1000
                                                    (000  O
                                                                   —  4000
                                                                   —  2000
                                                                   —  1000
                2010     2065     2055    2010
                         Lower    Higher
                          GNP     GNP
                        Assumption  Assumption
                                 2055     2055
                                 Lower    Higher
                                 GNP      GNP
                               Assumption Assumption
                         Additional Climate Change Impacts: Higher Sensitivity
                         Climate Change Impacts: Base Sensitivity
                         Base Case (No Climate Change)
Figure 16-2,
Potential impacts of climate  change on  electric
utilities,  United States

Source:   Linder and Inglis, Volume —.
                                    16-10

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                                                           Energy
billion dollars in 2010 and are $33-73 billion by 2055, a 7 to
15% increase over base case values for 2055.

     Figures 16-3 and 16-4 illustrate the diversity of the
estimated results for generating capacity on a state-by-state
basis.  The State and regional differences reflect differences in
current climate conditions (e.g., seasonal temperature patterns),
assumed future climate changes, and electricity end-use and
utility system characteristics  (e.g., market saturation of
weather-sensitive appliances and equipment).

     Figure 16-3 shows that estimated reductions in new capacity
requirements induced by climate change are limited to the winter-
peaking regions of the extreme Northeastern and Northwestern
States.  The Great Lakes, Northern Great Plains, and Mountain
States, as well as California, are estimated to experience
increased new capacity requirements by 2055 in the range of 0 to
10%.  Increases greater than 20% are concentrated in the
Southeast, Southern Great Plains, and Southwest.

     Figure 16-4 shows a somewhat similar geographic pattern of
impacts for electricity generation in 2055.  Reductions in
generation are estimated in the Northern States, and the greatest
increases are concentrated in the Southwest.  Despite substantial
use of air-conditioning in the Southeast, the estimated increases
in generation are only in the 5 to 10% range.  There is a
relatively high market saturation of electric heat in the region,
and the increase in cooling is partly offset by a decrease in
heating as a result of warmer winters.

     Because regions are affected differently, the results
indicate potential changes in the patterns of interregional bulk
power exchanges and capacity sales overtime and as climate
change.  For example, under the assumption of increasing
temperatures,  some regions may require significant amounts of
additional generating capacity to meet increased demands reliably
during peak (cooling) seasons, but may experience lower demands
in other (heating) seasons.  As a result, the region's needs may
be for power plants that are utilized heavily during only part of
the year.   Low annual utilization in the region would not justify
construction of high capital and low fuel cost baseload power
plants that can produce electricity more cheaply (per kwh) than
low capital and high fuel cost peaking units.  However, when
considered across several regions, the least-cost plan may be to
construct baseload power plants in certain regions,  utilize them
to an extent greater than required by the region,  and sell the-
"excess" electricity from these plants into other regions.  The
                              16-11

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Chapter 16
location and amount of these interregional sales would be subject
to the transfer capabilities of transmission capacity in place.


SOCIOECONOMIC AND ENVIRONMENTAL IMPLICATIONS

     Despite the limitations of the analysis and the need for
more research to refine the data and methods used,  the results
are judged to be reasonable estimates of potential  climate change
impacts associated with temperature change and its  effects on
electricity demand.  Key socioeconomic and environmental
implications of the results stem from the increases in electric
generating capacity and generation requirements associated with
climate-induced changes in demand.  The implications include the
following:

     o    Climate change could result in overall fuel mixes for
          electricity generation that differ from those expected
          in the absence of climate change.

     o    Regional differences in capacity and generation
          requirements suggest that important, new  opportunities
          for interregional bulk power exchanges or capacity
          sales may arise as a result of climate change.

     o    The impacts of uncertain climate conditions over the
          long term could pose significant planning and economic
          risks.  Because of long lead times required to plan and
          build economic baseload generating capacity, the
          ability of utility.planners to correctly  anticipate
          climate change could result in lower electricity
          production costs.  The magnitude of these risks in some
          regions  (e.g., the Southeast and the Southern Great
          Plains) could be similar to other uncertainties that
          utility planners and decisionmakers must  face.

     o    If the result is confirmed that the majority of new
          capacity requirements in response to climate change are
          for peaking capacity, a new technological and market
          focus would be directed at this type of generating
          plant.  Related to this would be increased R&D on
          electricity storage technologies,  which would allow
          lower cost, more efficient powerplants to generate, at
          off-peak times, electricity for use during peak
          periods.

     o    Because increases in customer demands -for electricity
          may be particularly concentrated in certain seasons and

                                          16-14

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                                                           Energy
          at peak periods, conservation and especially load
          management programs that improve the efficiency or
          change the patterns of customer uses of electricity
          could be more cost-effective when considered in the
          context of potential changes in climate.

          Increased demands could increase electricity imports,
          adversely affecting the U.S. balance of payments.

          Increased electricity generation implies increased
          adverse environmental impacts associated with the
          following:

               air quality (e.g., emissions of sulfur dioxide,
               NOX,' and other pollutants) ;

               land use for new powerplant sites, fuel
               extraction, fuel storage, and solid waste
               disposal;

          —   water quality and use  (e.g., for powerplant
               cooling and fuel processing); and

               resource depletion, especially of such
               nonrenewable fuels as natural gas, which may be in
               short supply.

          Of particular concern would be additional water
          withdrawal and consumption requirements in areas^ where
          water supplies may be reduced by climate change.*

          Increased electricity generation also implies increased
          emissions of CO2 and other greenhouse gases.   For
          example, if the estimated increases in climate change-
          induced generation reported in Table 16-1 were met by
          conventional technologies, C02 emissions could increase
      For example,  increased electricity  generation  induced by
climate change in Northern California could increase requirements
for  water withdrawal  by  600-1,200  million   ft3  and  for  water
consumption by 200-400  million ft3 in 2055.  Comparable  figures for
the Southern  Great Plains in 2055  would be water withdrawal of
5,800-11,500 million ft3 and consumption of 1,800-3,500 million ft3.

                                           16-15

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Chapter 16
          by 40-65 million tons per year^by 2010 and by 250-500
          million tons per year by 2055.**


POLICY IMPLICATIONS

     In general, the study results suggest that utility planners
and policymakers should begin now to assess more fully and to
consider climate change as a factor affecting their planning
analyses and decisions.  If more complete and more detailed
analyses support the socioeconomic and environmental implications
of the climate change effects described above, they should be
explicitly addressed in planning analyses and decisions.

Specific policy implications related to the findings include the
following:

     o    In formulating future National Energy Plans, the
          Department of Energy may wish to consider the potential
          impacts of climate change on utility demands.

     o    The interactions of climate change and the current
          efforts of the Federal Energy Regulatory Commission
          (FERC) to restructure the electric utility industry are
          difficult to assess.  For example, the industry's
          response to FERC policies could either accelerate or
          reduce the rate of emissions of greenhouse gases,
          depending upon changes in the mix of generating fuels
          and effects on the efficiency of electricity
          production.  The possible, alternative responses should
          be assessed, and FERC policies should be considered
          with respect to their potential implications related to
          climate change issues.

     o    Increases in electricity demands induced by climate
          change will make achievement of energy conservation
          goals more difficult.  For example, the draft
          conference statement from "The Changing Atmosphere:
          Implications for Global Strategy" (Environment Canada,
          1988) calls for reductions in C02 emissions  to be
          achieved in part through increased efforts in energy
          efficiency and other conservation measures.   An initial
i
     **
      Note,  however,  that  these  increases  in  emissions  from
electricity production could be offset at least in part by reduced
demand for space heating provided by natural gas and oil furnaces
or by other direct uses of fossil fuels.

                                          16-16

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                                                           Energy
          goal for wealthy, industrialized nations set by the
          conference is a reduction in C02 emissions through
          conservation of approximately 10% of 1988 emissions
          levels by 2005.  The impacts of climate change to
          increase electricity demand should be factored into the
          policies and plans designed to achieve this
          conservation goal.

          Similarly, climate change impacts may exacerbate the
          difficulties or costs associated with implementing acid
          rain mitigation strategies being considered by the
          Congress.  However, these strategies center primarily
          on near-term solutions focusing on emissions reductions
          from existing powerplants, and the impacts of climate
          change may not be large within that time frame.
RESEARCH NEEDS

     Important areas for further climate change research include
improved methods for developing and disseminating climate change
scenarios, with particular emphasis on (1) estimates of variables
(in addition to temperature) relevant to impact assessment  (e.g.,
hydrologic factors, winds); (2) estimates of the possible impacts
of global warming on variations in weather conditions and the
occurrence of extreme events;  (3) continued attention to
estimates of the rate of climate change over time; and  (4)
estimates of climate change at a more disaggregated regional or
local level.

     Follow-on research suggestions on the utility side include
(1) refinement of the analytical approach, in part through
lessons learned from additional utility-specific analyses;  (2)
more detailed and complete analyses of the weather sensitivity of
customer demand for electricity; (3) extension of the approach to
consider other pathways (including indirect and secondary
effects) in which climate change could affect utility investments
and operations; and (4) an assessment of the value of improved
climate change information- to utility planners and managers.
                                           16-17

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Chapter 16
REFERENCES

Environment Canada.  1988.  The Changing Atmosphere:
Implications for Global Security Conference Statement.
Environment Canada, Government of Canada.  Toronto.  June 27-30,
1988.

Linder, K.P., M.J. Gibbs, and M.R. Inglis.  ICF Incorporated.
1987.  Potential Impacts of Climate Change on Electric Utilities.
Report 88-2.  Albany, New York: New York State Energy Research
and Development Authority.  (Note:  Publication of the report by
the Electric Power Research Institute, Palo Alto, California, is
forthcoming.)

Stokoe, P.K., and M. LeBlanc.   P. Lane and Associates, Ltd., and
Discovery Consultants, Ltd.  1987.  Socio-economic Assessment of
the Physical and Ecological Impacts of Climate Change on the
Marine Environment of the Atlantic Region of Canada, Phase I.
Halifax, Nova Scotia, Canada:  School for Resource and
Environmental Studies, Dalhousie University.
i
                                           16-18

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Chapter 17
                           CHAPTER  17

       ANALYSIS OF  CLIMATE VARIABILITY AND EXTREME EVENTS
FINDINGS

Climate variability is an important factor needed for detailed
climate impact studies.  Analysis of changes in variability
estimated by two GCMs is inconclusive.  Inconsistencies are
obtained in comparing the changes in climatic variability with a
changing climate calculated by two different global circulation
models (GCMs) in four regions of the United States.

          For interannual variability the GISS model produces
          reduced variability for temperatures for January -
          April but varied results for the other months.  The
          interannual variability of precipitation tends to
          increase, although not consistently.

     —   The GISS model suggests reduction in the variability of
          daily temperature with warming, but these results are
          not statistically significant on a regional-by-regional
          basis.  The NCAR model (Washington version) produces
          both increases and decreases in daily temperature
          variability (although most of these changes are not
          statistically significant).   The daily variability of
          precipitation with a warming climate tends to increase
          in the majority of cases (months and locations).

          The amplitude of the diurnal cycle (GISS results) tends
          to decrease in summer with warming.  In the other
          seasons, both increases and decreases occur.

o    On the basis of the mixed model results on how climatic
     variability will change with a changed climate, the
     assumption of no change in variability in the scenarios used
     for this report must be recognized as reasonable, given the
     current state of knowledge.

o    Comparison of observed and model results for the current
     climate for the two GCMs for selected regions of the United
     States reveals both interesting contrasts and similarities
     regarding the reproduction of climate variability.

          Regarding mean statistics for temperature and
          precipitation, there are significant discrepancies in
          both models, compared to observed values in all four

                               17-1

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                                              Climate Variability
          regions examined.   The GISS model is in general too
          cool in summer and fall,  whereas the NCAR model is
          either too warm or too cool, depending on the region
          and the time of year.  Errors for both models are in
          general on the order of several degrees C. The GISS
          model and the NCAR model (Chervin version) consistently
          overpredict precipitation in the four regions.

          Additional comparisons of mean values of precipitation
          and temperature with two additional versions of the
          NCAR model revealed both under and over estimations of
          mean precipitation, whereas mean annual temperature was
          consistently overestimated.

          The interannual variability of relative humidity and
          absorbed radiation (NCAR results)  are fairly well
          reproduced by the model,  but tend to be slightly lower
          than the observed.  The daily variance of relative
          humidity is much lower than the observed at all
          locations examined.

          The GISS model overestimated interannual variability of
          temperature, whereas the NCAR model (Chervin version)
          tends to underestimate it.  Both models reproduce the
          variability "reasonably well" at some locations some of
          the time.

          Both models reproduce the relative variability of
          annual precipitation fairly well at all locations,
          although the GISS model overpredicts the absolute
          variability.  There are indications that both models
          fail to properly reproduce the daily variability of
          precipitation.  Both underestimate the frequency of
          light rain days, and overestimate the frequency of
          high-intensity rain days. .

          Explanations for some discrepancies, such as why the
          daily variances of temperature are too high, relate to
          how the surface hydrology is modeled in both models.
          More investigations of model results are necessary in
          order to improve understanding of future changes in
          climate variability.
NATURE AND IMPORTANCE OF CLIMATE EXTREMES

     The impacts of climate change on society accrue not
necessarily from the relatively slow trends in the mean of a

                               17-2

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Chapter 17
climate variable, but rather from the attending shifts in the
frequency of extreme events.  This issue has already received
some attention in the literature (e.g., Schwarz, 1977; Parry,
1978; Mearns et al., 1984) Where the nonlinear relationship
between changes in the mean and extreme events has been
underlined.  However, less |s known about this factor than about
most other aspects of climate change.

     For the purposes of climatic impact analysis, Heathcote
(1985) states that extreme climatic events may be considered
"short term perturbations of the energy flows which provide
magnitudes outside the normal spectrum or range of the typical
period."  What constitutes normal is, of course, a central issue
in defining extremes as well as what constitutes the averaging
period.

     Extreme events relevant to impact analysis function in
different time scales, depending upon the climate variable
involved and the impact area of interest.  Thus, events can range
from the length of time (in minutes and hours) that minimum
temperatures in Florida remain below a critical value, resulting
in damage to citrus crops, to the length of time (in months and
years) that precipitation is particularly low in California,
resulting in serious water shortages for industry and
agriculture.  The probability of extreme events can also vary
considerably, for example, a range from recurrence intervals for
extreme snowfall in the Buffalo, New York, area of a magnitude
similar to that of the 1976-77 winter (1/20,000 or 0.00005), to
heat waves (temperatures above 100°F  for 5 consecutive days)  in
Dallas, Texas (0.38).

     What defines an event as extreme is not only a certain
statistical property (for example,  likely to occur less than 25%
of the time), but also how prepared a particular system is to
cope with an event of such magnitude.  Hence very few extreme
events have a fixed absolute value independent of particular
response systems at a particular location.  This implies that
what constitutes an extreme event can also change over time due
to changes in the relevant response system (Heathcote, 1985).

     It is thus very difficult to comprehensively review all
climatic extreme events of importance to society, and what is
presented here is far from an exhaustive catalogue.  Because one
of the purposes of this review is to highlight the extreme events
of importance that can serve as guides for choosing the extreme
events that should be quantitatively analyzed in general
circulation model (GCM)  doubled C02 experiments,  priority  is


                               17-3

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                                              Climate Variability
given to events related to relatively easily analyzable
variables.

     This review considered the two most important climate
variables and their extremes (maxima and minima) and one major
meteorological disturbance:  temperature, precipitation, and
severe storm effects.  Extremes in these variables affect the
areas of energy use and production, human mortality and
morbidity, agriculture, and unmanaged ecosystems (although not
all areas are discussed under each climatic extreme event).  It
should be noted that although the research on extreme climate
events not as extensive for natural ecosystems as for some of the
other are as covered here, in present research on climatic change
impacts on forest ecosystems, the primary importance of
variability changes has been underlined (e.g., by Soloman and
West, 1985) who assert that climate variance controls geographic
ranges of mature tree species,  and the rates and outcomes of
plant succession; and in chapter 11 of this report where
limitations of the EPA forest studies since they did not consider
change in climate variability,  are discussed).

Temperature

     Given the scientific consensus that higher atmospheric
concentration of greenhouse gases will raise average global
temperatures, extreme temperature effects are given priority in
this analysis.

Maximum Temperatures

     The area of extreme temperature effects that has received
the most attention in the scientific literature is the effects on
human mortality and morbitidity (e.g., Kalkstein, 1988; Becker
and Wood, 1986; Jones et al., 1982; Bridger et al., 1976; and
Ellis, 1972).  This is partly because the relevant climatic
factors  (i.e., maximum daily temperatures and relative humidity)
are readily available for analysis.

     Heat waves consist of a series of days with abnormally high
temperatures.  Examples include the 1980 heat wave in the United
States when Kansas City had 17 consecutive days above 102°F, St.
Louis had 16 days above 100°F (Jones et al., 1982), and Dallas
had 42 consecutive days with temperatures above 100°F (Becker and
Wood, 1986).  The death toll that year was several times above
normal (1,265 lives).  Major heat waves of at least regional
extent in the United States in this century occurred in 1901
(9,058 deaths in the Midwest),  1934, 1935, and 1936 (4,768 deaths
nationwide in 1936 alone), 1954, 1955, 1966, and 1980.

                               17-4

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Chapter 17
     Studies have specifically tried to pinpoint the most
significant meteorological factors associated with heat-related
death and illness.  Oeschli and Buechley (1970) identified the
maximum temperature with a 1-day time lag for three Los Angeles
heat waves.  Jones et al. (1982) determined that high maximum
temperatures, the number of days that the temperature is
elevated, high humidity, and low wind velocity contributed to
excess mortality in Kansas City and St. Louis in the 1980 heat
wave.  Kalkstein et al. (1987) established for New York City that
runs of days with high minimum temperatures, low relative
humidities, and maximum temperatures above 92°F contributed to
heat-related deaths.  In a more comprehensive study (reviewed in
Chapter 14, Health), Kalkstein  (1988) established statistical
models relating weather and mortality to heat intensity.

     Increases in heat waves are virtually certain, assuming
global warming.  But how they increase (longer or greater
departure from the mean) very much depends on changes in
variability that would affect the persistence of high
temperatures.

     Such crops as corn, soybeans, wheat, and sorghum are
sensitive to high temperatures during their bloom phases.  For
example, Shaw (1983) reported that severe temperature stress
during a 10-day period around silking will result in crop
failure.  Corn silking is a very critical period, during which
the number of kernels on the ear are determined.  Barnell and
Eftmescu (1973) reported that maximum temperatures exceeding 32°C
around tasseling and silking resulted in high rates of kernel
abortion.  Thompson (1968) developed a statistical model to
determine corn yields and found that the accumulation of daily
maximum temperatures greater than 92 *F in July and August was
negatively correlated with yield.  McQuigg (1981) reported that
the corn crop was severely damaged in July 1980 as a result of
temperatures exceeding 100°F.  The destructive effects of runs of
hot days on corn yields was particularly in evidence in 1983 in
the U.S. Corn Belt.  Although the damage from high temperatures
is best documented for corn, it has also been noted in wheat and
soybean yields (e.g.,  Neild, 1982; Mederski, 1983).

     Although not as much research has been performed on the
effects of temperature extremes on natural ecosystems, some
research has been done on forest responses to temperature
extremes.  Solomon and West (1985) indicate in their summary of
climate effects on forests that the frequency, intensity, and
lengths of heat waves under climate change conditions are
important factors influencing seedling survival, and can

                               17-5

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                                              Climate Variability
contribute to the loss of a species from an ecosystem.  A run of
warm years can affect the location of tree lines.  Schugart et
al. (1986) established that a period of warm summers at high
altitudes during the 1930s, when the mean annual temperature was
no more than 1°C higher than average, resulted in a burst of
regeneration in boreal forest trees near polar and altitudinal
limits in North America.

     High temperatures have their most immediate impact on energy
by causing an increase in demand for electricity for air-
conditioning.  In a report prepared for New York State, the
potential impacts of climate change on electric utilities were
investigated.  Using climate scenarios similar to those used by
EPA (see Chapter 3), Linder et al. (1987)  found that energy
demand would significantly increase in summer (on the order of 3%
for an average August day in 2015 for downstate New York).  Net
energy demand would increase, even though winter heating demand
would fall.  The study was limited by the way the climate change
scenarios were developed.  For example, it assumed that the
distributions of daily, monthly, and seasonal temperatures all
change consistently by the same amount.  Since energy demand is
affected by changes in extremes, the omission of potential
changes in variability limited the study.   This is obviously the
case for electricity demand is concerned,  since capacity is
determined in part, by peak demand, and peak demand is
determined, in part, by heat waves.

Minimum Temperatures

     Since it is presumed that extreme minimum temperatures will
be less of a problem with C02-induced climate change,  they
receive less attention here.  However, changes will most likely
occur in the growing areas of certain crops, where risks of frost
damage, for example, may not be clearly known.

     The best example of frost damage to crops is the effect of
low minimum temperatures on citrus trees;  this issue has been
studied in depth for the citrus crop in Florida.  (See Glantz,
Volume X, for a discussion of the Florida citrus industry's
responses to freezes in the early 1980s.)   The most striking
aspect of these freezes is the very short freezing time necessary
for damage to occur.  New citrus growth (i.e., bloom buds) can be
completely killed during a 30-minute exposure to 26°F or a 3-hour
exposure to 28°F.  The effect of freezes is exacerbated if the
crops have not hardened with the cold.  Thus, if a freeze follows
a warm period (i.e., indicating high daily temperature
variability) when dormancy has been broken, more damage will
occur at less extreme temperatures.  A recent example of a freeze

                               17-6

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Chapter 17
that affected the Florida citrus crop was the 1983 freeze,
December 24-26, which resulted in a 30% reduction in citrus yield
compared with the previous year (Mogil et al., 1984).

     Extreme lows on a seasonal basis tend to most directly
affect winter energy use for heating.  The difference in heating
fuel use in the United States between a warm and a cold winter
can vary by as much as 400 million gallons of oil.  During the
extremly cold winter of 1976-77, heating degree days (calculated
on a base of 65°F) were 10% greater than normal for the nation as
a whole (Dare, 1981).

Precipitation

     Anticipated changes in precipitation through climate change
are not well known at this point.  However, it is likely that
geographic shifts in rainfall patterns will occur, with increases
in annual total precipitation, decreases in different U.S.
regions, and changes in the seasonal distribution of
precipitation.  Changes in the frequencies of extremes of both
droughts and floods must be considered.  Drought is of particular
interest at the time of this writing because of the current
drought in the United States and the energetic speculations being
made concerning its possible connection with CO2-induced climate
change  (Wilford,  1988).

Drought

     The most basic definition of drought may be lack of
sufficient water to meet essential needs (Gibbs, 1984).  It is a
condition determined relative to some long-term average condition
of balance between rainfall and evapotranspiration in a
particular region (Wilhite and Glantz, 1987).  Different types of
drought are recognized, such as meteorological drought (a
departure of precipitation from normal), agricultural drought
(insufficient soil moisture based on crop growth needs), or
hydrological drought (based on departures from normal or relevant
hydrologic parameters, such as streamflow).  These "types" of
drought are not completely independent, but can show up at
different time lags one from the other.

     Drought of any kind is anomolous as an extreme
climatological event in that it is a "creeping" phenomenon;
neither its onset nor its end is clearly punctuated in time.  It
is difficult to measure drought severity, since drought is a
combination of factors:  duration, intensity, and areal extent.
Drought also can be one of the longer lived extreme events in
                               17-7

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                                              Climate Variability
that it can be measured in terms of seasons or, more frequently,
years.

     In the United States, major droughts have usually been
defined in terms of several years, and the rate of occurrence is
most strongly influenced by interannual variability of
precipitation.  Major drought episodes in the United States in
the 20th century occurred in 1910, 1911, 1913  (serious but short
lived), the 1930s (particularly 1934-36), the 1950s (1953-1957,
primarily in the southern Great Plains), 1961-66 (northeastern
United States), 1976-77 (primarily California and sections of the
northern Great Plains), and the current drought (1988), which has
been compared to drought conditions in 1936.

     Although much research has been aimed at forecasting and
planning for drought under the current climate (e.g.,, Wilhite and
Glantz, 1987; Rosenberg, 1978, 1979) we still remain highly
vulnerable to its impacts, as is being vividly demonstrated by
current reports of agricultural disaster in areas of the northern
Great Plains and forecasts of serious economic ramifications from
the ongoing drought.

     The effect of drought on crop production is perhaps the
impact of drought that has received most research attention.  The
occurrence of droughts has been a major cause for yearly
variability in crop production in the United States (Newman,
1978) .  During the 1930s,  drought yields of wheat and corn in the
Great Plains dropped as much as 50% below normal, whereas the
drought in the 1950s brought less dramatic declines in yields
(Warrick et al., 1975).  The reduction in vegetative cover
associated with drought also brings about severe soil erosion,
which will diminish future crop productivity.  Low yields of
forage crops result in inadequate food for livestock and
premature selling off of livestock.

     Soil moisture deficits affect natural vegetation as well as
crops.  Again, much of the research in natural ecosystems has
been on forests.  Soloman and West (1985) identify drought as the
cause for death of seedlings and for slowed or stopped growth of
mature trees.

     Aside from the direct effects of insufficient moisture on
unmanaged ecosystems, indirect effects also result from increased
incidence of fires.  In the Australian drought of
1982-83, for example, brush fires destroyed over 8,000 km  of
land; most of this area was forested (Gibbs, 1984).  During the
drought of 1988, forest fires have broken out across the country.


                               17-8

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Chapter 17
     The effects of drought on U.S. energy resources are most
obvious with regard to the generation of hydroelectric power.  In
the study described above on the impacts of climate change on
electric utilities (Linder et al., 1987), the effect of decreased
streamflow due to drought on the production of hydroelectric
power in New York was discussed.  In New York, 25% of electricity
is supplied by hydrogeneration, mainly from the Niagara and St.
Lawrence projects.  Historical fluctuations have been extreme at
times, as seen in 1964 during the northeastern drought when the
Niagara Project generated 36% less energy than normal (Linder et
al., 1987).  Other regions of the country are even more dependent
on hydrogeneration of electricity.  Two-thirds of the total
electricity in the Pacific Northwest is generated by hydropower.
In this region, large variations in energy capacity result from
variability in precipitation (Northwest Power Planning Council,
1983) .

Floods

     On average, 200 people die each year from flooding; flash
floods account for most of these deaths (AMS, 1985).    Floods
also destroy property, crops, and natural vegetation, and disrupt
organized social systems.

     Floods result from a combination of meteorological extremes
(heavy precipitation from severe storms, such as hurricanes and
thunderstorms), the physical characteristics of particular
drainage basins, and modifications in drainage basin
characteristics made by urban development.  Loss of life and
property is increasing as use of vulnerable floodplains
increases.

     The recurrence interval of flooding is most important in
applying effective control and protection mechanisms.  These
include building dams, reservoirs, and levees, and improving
channels and floodways (White et al., 1975).  For example, flood
control reservoirs are designed to operate at a certain level of
reliability, and the reliability is determined by a certain flood
magnitude that the reservoir can handle, such as a 100-year
flood.*  Hence,  the statistics  of  flooding are key  for designing
for protection and are based on a certain climatic variability
determined from the historical record.  As that variability
changes, the reliability of the protection system will change.
      A 100-year flood is a flood of a certain magnitude specific
to a drainage basis, which has a 1% probability of occurring in a
year.

                               17-9

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                                              Climate Variability
     This is currently seen in systems where longer precipitation
and streamflow records change the recurrence interval of
particular magnitudes of flooding, such as in the case of Folsom
Dam in northern California (Reibsame, 1987).  Overtopping of dams
accounted for 33% of total flood loss during 1903-58.  During
1900-79, 26% of dam failures were due to overtopping (Clark,
1987).  In 1972, overtopping of levees accounted for at least 40%
of losses from tropical storm Agnes, which was one of the largest
natural catastrophes in terms of property damage.  With changing
variability in climate, overtopping could become more common, and
losses from floods could increase.

     Major recent floods include the following:  (1) Rapid City,
South Dakota (June 1972), 231 deaths, more than $100 million in
damage; (2) northeastern United States (June 1972), 120 deaths
and about $4 billion damage — inundation from hurricane Agnes;
(3) Big Thompson Canyon, Colorado (July 1976), 139 deaths, $50
million in damage — a result of a stalled thunderstorm system
that delivered 12 inches of rain in less than 6 hours (Henz and
Sheetz, 1976); (4) Johnstown, Pennsylvania (July 1977), 76 deaths
and $200 million in property damage — a result of slowly moving
thunderstorms that deposited 11 inches of rain in 9 hours.

     Floods in the 1980s have been less serious in terms of loss
of life, but changing frequencies of severe storms, such as
thunderstorms and hurricanes as well as general shifting of
precipitation patterns could result in unprecedented losses from
floods in a climate-changed world.

Severe Storms - Hurricanes

     Three important kinds of climatic extremes are present in
hurricanes:  strong winds, intense and high precipitation
amounts, and extreme storm surges.  A hurricane is an extreme
form of a tropical cyclone, characterized by torrential rains,
typically as much as 5 to 10 inches in one storm; high
windspeeds, which can exceed 100 mph; very steep pressure
gradients, with pressure at the center as low as 915 millibars
(mb) and with diameters of 100 to 400 miles.

     The deadliest hurricane to hit the United States was the
Galveston hurricane of 1900, which killed 6,000 people.  However,
the deadliest hurricane worldwide struck Bangladesh in 1970,
resulting in 300,000 deaths.  Hurricane Agnes in 1972 caused over
$4 billion in damages to Florida and the northeastern United
States.   (Much of this damage resulted from flooding inland in
the Northeast.  Damages from high winds and surges were confined
to coastal areas.)  Hence, the frequency and intensity of

                              17-10

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Chapter 17
hurricanes is of major concern for the inhabitants of U.S.
regions where they commonly occur — i.e., the gulf and the South
Atlantic coasts.

     Hurricanes are classified according to their severity on the
Saffir/Simpson Scale (1-5), taking into account the central
pressure, windspeed, and surge.  Major hurricanes are considered
all those of categories 3-5 wherein central pressure is less than
945 mb, windspeeds exceed 110 mph, and the surge is greater than
8 feet (Herbert and Taylor, 1979).

     From 1900 through 1978, 53 major hurricanes (categories
3-5) directly hit the United States (averaging two major
hurricanes every 3 years).  Overall, 129 hurricanes of any
strength hit the United States, which averages to approximately
two per year.  In recent decades, the number of major hurricanes
has declined.  From 1970 to 1978, only three hurricanes occurred
compared with six or more in earlier decades.  The last hurricane
of category 4 or 5 to strike the United States was hurricane
Camille in 1969.  (Hurricane Allen (1980), which at one time
reached force 5, weakened before it struck a relatively
unpopulated segment of the Texas coast (Oliver, 1981).)  Since
then, the population of the south coastal regions of the United
States has grown tremendously, and most inhabitants have never
experienced a major force hurricane.  Building in coastal areas
has also increased with population, which raises the potential
for high property damage.  Thus, the population may be more
vulnerable and less prepared to handle this particularly
devastating extreme event (Sanders, 1982).  Any increase in the
frequency and/or intensity of these storms, which could result
from climate change, would be of great concern to south coastal
regions of the United States.

     Coleman (1988)  has found some limited evidence for increased
frequency on the basis of examining the historical record for the
number of storms formed in the North Atlantic during years of
warmer than average sea surface temperatures.  Emmanuel (1988a)
has found through a hurricane modify experiment that the
intensity of hurricanes increase under warmer conditions.  The
extreme intensity of Hurricane Albert this past summer is
consistent with the findings.  Emmanuel (1988b) also asserts the
importance of establishing a general theory of hurricane
development independent of current atmospheric conditions, so
that scientists can predict changes in frequency and intensity of
storms with climate change.
                              17-11

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                                              Climate Variability

                                                                   ™
PRIOR STUDIES ON THE MODELING OF CLIMATE VARIABILITY

     Studies comparing variability statistics of observed time
series with variability statistics of general circulation model
(GCM)-generated time series of climate variables relevant to
climate impacts are not numerous in the atmospheric sciences
literature, although studies first appeared in the early 1980s
(e.g., Manabe and Hahn, 1981; Chervin, 1981).  Such studies are
critical if climate change research is to determine if the
variability statistics of doubled C02  experiments with GCMs are
valid.  To accomplish this, the ability of GCMs to reproduce the
variablity statistics of the present-day climate must be
examined, and a thorough understanding of descrepancies attained.
Five of the more recent and relevent works that address
comparison of variability are briefly reviewed in this section.
Very often, these studies also involve a study of the change in
variability under doubled CO2 conditions.

     Chervin (1986) investigated interannual climate variability
and climate prediction.  He designed a special version of the
NCAR, CCMO (National Center for Atmospheric Research Community
Climate Model)  to eliminate external variability of interannual
time series of climate variables, so that discrepancies between
modeled and observed variability would reflect the external
component of variability present in the observed data.  The
additional variability attributed to external boundary conditions
is considered the potential predictability of the climate.  The
model was modified such that external boundary conditions
remained the same each year of the 20-year model run.  This
entailed the prescription of monthly sea surface temperatures and
sea ice distributions.  The variability of mean sea level
pressure and 700-mb geopotential height (which is related to
large-scale wind patterns) were analyzed in the Northern
hemisphere, with particular focus on the United States.  Results
indicated no significant differences, between modeled and observed
variabilities of mean sea level pressure over the United States
and only limited areas of differences in the variability of 700-
mb geopotential height.  It should be noted, however, that these
results are based on the assumption that processes responsible
for the internal variation of the atmosphere are correctly
incorporated in the model.

     Bates and Meehl (1986) also used the CCM to investigate
changes in the frequency of blocking events on a global scale
under doubled C02 conditions.   Their version of the CCM included
a seasonal cycle, computed hydrology,  and a simple mixed layer
ocean.  The statistics of the 500-mb height field  (the height
above the surface at which atmospheric pressure equals 500 mb)

                              17-12

-------
Chapter 17
are examined, as are blocking events defined as persistent
positive height anomalies (which indicate high pressure).
Blocking events are strongly related to persistent surface
temperature anomalies, such as heat waves in the summer.  Hence,
changes in the frequencies of blocking events have significant
implications for changes in the frequencies of extreme
temperature events.  In comparing modeled data with observed data
for a 10-year period, they found that the model does a
"reasonable" job of simulating 500-mb height standard deviations,
particularly in winter in both hemispheres. .The model, however,
produces too few extreme blocking events.  Under doubled C02
conditions, standard deviations of 500-mb height and blocking
activity were found to decrease in all seasons (i.e., the
variability of blocking events decreased).

     Two studies were recently conducted on local or regional
scales using the U.K. Meterological Office 5-layer GCM. Reed
(1986) analyzed observed versus model control run results for one
gridpoint in eastern England, and addressed the problem of
creating the correspondence between the model grid square and the
spatial average of several observation points.  He analyzed the
mean and variance of temperature for a 3-year integration of
model runs.  Compared to observations, the model tended to
produce temperatures that were too cool and variability that was
too high as measured by the standard deviation.  For
precipitation, the model produced too many rain days but did not
successfully simulate extreme rain events of greater than 20
mm/day.

     Most recently, Wilson and Mitchell (1987) examined the
modeled distribution of extreme daily climate events over Western
Europe, using the same model.  Comparisons were made of minimum
surface temperatures and precipitation.  Again, the model
produced temperatures that were too cold, and hence, extreme
minimum temperatures were overestimated.  This problem was most
pronounced in grid boxes away from the coasts.  The model also
produces too much precipitation in general, but does not
successfully reproduce observed highest daily totals.  The number
of rain days is overestimated.  Wilson and Mitchell examined
changes under qradrupled C02  conditions and found that
variability of temperature generally decreased, which given the
general warming,  indicates a marked reduction in the occurrence
of freezing temperatures.  The authors compared the changes in
intra-annual temperature variability using the more rigorous
procedures of Katz (1984) as well as using the more standard
F-test.  Both tests indicate a signicant decrease in winter
temperature variability.  The authors emphasized the importance
of examining variables of importance to climate impact analysis,

                              17-13

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                                              Climate Variability
but also of using a model that faithfully reproduces the
present-day climate in terms of means and extremes.

     Hansen et al. (1988) used the GISS model II general
circulation model to simulate the global climate effects of time-
dependent variations of atmospheric trace gases and aerosols.
Several different scenarios of trace gas increase from 1958 to
the present were used.  A one hundred year control run was also
produced.  From this run it was determined that globally the
model only slightly underestimates the observed interannual
variability.  However, the model's variability tends to be larger
than observed over land.  Among the calculations made with output
from the transient (i.e. progressive climate change) run were
changes in the frequencies of extreme temperature events.  This
was accomplished by adding the change in temperature with climate
warming predicted by the model to observed local daily
temperatures.  Hence the authors assumed no change in variability
in making these calculations.  Results indicate that predicted
changes in the frequency of extremes beyond the 1900s at such
locations as New York, Washington, and Memphis, become quite
large, and would have serious impacts.

     The studies reviewed above indicate some important
shortcomings of GCMs with regard to their ability to faithfully
reproduce observed variability statistics.  More research is
clearly needed to further determine the sensitivity of the models
to changes in physics, resolution, and so forth, with regard to
the determination of variability.  Moreover, only one of these
studies explicitly concerns variables of importance to climate
impact analysis.  Studying the higher moments (e.g. variance) of
climate variable statistics, and carefully verifying the models'
ability to reproduce observed variability on regional scales, are
the necessary prerequisites to rigorously analyzing possible
changes in these statistics under doubled C02 conditions.


STUDIES FOR THIS REPORT

     Two research efforts were undertaken for this report to
attempt to increase knowledge concerning how climate variability
will change.  The climate change scenarios for use in the climate
change impact studies reviewed in this report excluded
consideration of changes in variability (see Chapter 3).  The
following two studies on GCM estimates of current and future
variability were performed for this report:

     1.   Variability and the GISS Model - Rind, Goldberg, and
          Ruedy, Goddard Institute for Space Studies.

                              17-14

-------
Chapter 17
     2.   Variability and the NCAR Model - Mearns, Schneider,
          Thompson and McDaniel, National Center for Atmospheric
          Research.

     It should be recalled that scenarios of climate change
generated by the GISS GCM are used in most of the impact studies
summarized in this report.  The results of these two studies are
directly compared in a later section.

The GISS study

     Rind et al. (1988) examined how well the GISS GCM simulates
the observed variability of climate by comparing the model and
the observed interannual and daily variations of temperature and
precipitation.  They describe the model assessment of changes in
variability of these two major climate variables under climate
change using the GISS doubled C02 run and a transient climate
change experiment in which trace gases are increased gradually.
The analysis is conducted in four regions of the United States,
which are the four regions upon which this report is focused:
the Great Plains, the Southeast, the Great Lakes region, and the
West Coast.  The locations of the four model grids representing
these areas are indicated in Figure 17-1.

     The GISS model, a grid general circulation mode, is run at
the 8 by 10* resolution, and the results are analyzed for four
different grid boxes corresponding to the regions listed above.
Observed data consist of the average of observations at 9
different stations per grid box.  Grid boxes are indicated in
Figure 17-1.  First, mean conditions are compared for actual
weather observations with the GCM control run (or single C02) ,
the doubled C02 run,  and the transient run.   The model values for
mean temperatures for 4 months in the four regions are generally
cooler than observations (particularly in summer and fall), they
are always within several degrees Celsius of the observations.
Model precipitation values are fairly close to observed values in
the Great Lakes and Southeast grid boxes, but model values are
higher than observed for the other two regions  (e.g., January in
the southern Great Plains: model =2.1 mm/day, observed =0.46
mm/day).  Under the doubled C02 scenarios,  temperatures increase
over the control run by 4-6°C in the winter and 3-4°C in the
summer.  Warming in the transient scenarios is progressive, but
temperature change occurs more gradually than with simply
doubling the C02 amount.   Winter warms more than summer,  and  so
the annual seasonal cycle is reduced under climate change.
Precipitation changes are not statistically significant at
individual grid, but there is an overall tendency for increased
precipitation.

                              17-15

-------
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Chapter 17
Interannual Variability

     Standard deviations of temperature and precipitation of
observed and modeled data were compared for all months.  In most
months, the model year to year temperature variability is similar
to the observed variability in the four regions, but in summer
the variability was overestimated by 0.3-0.6'C. Precipitation
variability is overestimated in half of the cases where
precipitation amount is also overestimated.  The relative annual
variability of precipitation (that is the standard deviation
relative to the mean) of the model is generally in agreement with
observations.

     Under conditions of climate change (doubled CC>2)  in
comparing control versus climate change interannual standard
deviations (a sample size of 10 years in each case) for each
month in all regions, there is generally reduced variability of
temperature from January through April.  (These results were
further substantiated by examining the changed variability at
other tropical grid boxes in the United States.)  Results for
other seasons of the year are more ambiguous.  For precipitation,
the doubled C02 climate resulted in increased variability in most
months at the four grids (in 31 of 48 cases), but was
particularly striking at the southeast grid.  These changes,
however, were often of the same order as the model's natural
variability (from examination of the 100-year control run).  The
sign of the change in mean value and the sign of change in
interannual variability are highly correlated.

Daily Variability

     Daily variability of temperature was analyzed by
taking the daily departures from monthly means and comparing the
resulting model distribution with the distribution formed in the
same manner from the observational data.  Two statistical tests
were used.

     Ten years of control run for the transient experiment for
4 months (January, April, July, and October) were compared with
30 years of observations.  Distributions of observed versus model
daily temperature data were, in general, not significantly
different.  Comparisons were also made by calculating the
standard deviations of the departures from the mean for the four
months (Table 17-la).  These results indicate that the model's
values are significantly greater than the observed, which
demonstrates that the model is producing too many extremes.
                              17-17

-------
                                          Climate Variability
Table 17-la.
Daily Temperature Standard Deviations  (°C)
(Rind et al.)
Month
January




April




July




October




Observed
Location SD
Southern
Great Plains
Southeast
West Coast
Great Lakes
Southern
Great Plains
Southeast
West Coast
Great Lakes
Southern
Great Plains
Southeast
West Coast
Great Lakes
Southern
Great Plains
Southeast
West Coast
Great Lakes

4.81
4.53
3.63
4.97

3.72
3.71
2.59
4.65

1.74
1.50
2.40
2.38

3.79
3.59
3.15
4.09
Current 2010s
SD SD

8.15
6.90
5.86
5.79

5.77
5.50
4.29
6.15

2.56
2.34
3.56
3.02

5.16
5.21
6.51
5.46

0.61
-0.14
-0.61
0.44

-0.57
-0.65
0.77
-0.51

0.54
0.14
0.03
-0.48

1.16
-0.54
-0.55
-0.37
2030s
SD

-1.19
-1.14
0.05
-0.33

-0.27
-1.61
0.60
-0.26

-0.19
-0.22
0.54
-0.84

0.97
-0.25
-0.30
0.91
.2060
SD

-0.83
-0.23
-0.16
-0.44

-0.80
-1.24
0.33
-1.39

0.18
-0.24
0.28
-0.14

1.35
-0.73
-0.80
-0.06
                          17-18

-------
Chapter 17
     Under climate change, comparing temperature distributions of
the control run with a series of decades from the transient
experiment reveals that the distributions did not significantly
differ.  Results comparing standard deviations (presented in
Table 17-la) indicate that, although changes with time are not
strictly progressive, most cases by the end of the climate change
experiment show reductions in the standard deviation (although
these reductions are not statistically significant).  Hence, a
decrease of daily temperature variability is not demonstrated by
these results.

     For precipitation, comparisons are more complex.  For
example, the number of observation stations used to represent a
grid box does affect the results.  Model rainfall distributions
differ significantly from observed in half of the cases (in three
seasons for the West Coast and the southern Great Plains).  The
model also produces less days of light rain in general and more
extreme values in the winter in all four regions.  These results
are also confirmed by comparison of standard deviations (Table
17-lb).

     As the climate warms, again considering the various decades
of the transient experiment, the precipitation distributions
differ from the control climate in about one-fourth of the time
with no general progression over the decades.  Figure 17-2
presents a sample set of distributions for precipitation during
several decades of warming for the West Coast in April.  In
comparing standard deviations (Table 17-lb),  in half of the
cases, the warmest time period exhibits increases in standard
deviations.  These results are again consistent with those for
interannual variability.

Variability of the Diurnal Cycle

     It would be expected that the diurnal cycle would decrease
under changed climate as the additional greenhouse gases could
limit nighttime cooling.  Comparisons of control model results
with observations are reasonable in the four regions.  Under
doubled C02 conditions,  it was  found  that  the amplitude of  the
diurnal cycle very definitely decreases in summer but changes
inconsistently in the other seasons.   The reason for this is the
dominance of radiative heating in the summer and of other forms
of heating and cloud cover change in other seasons.
                              17-19

-------
                                              Climate Variability
Table 17-lb.
Daily Precipitation Standard Deviations (mm d~1)
(Rind et al.)
                       Observed   Current   2010s   2030s   .2060
 Month     Location       SD        SD       SD      SD       SD
January




April




July




October




Southern
Great Plains
Southeast
West Coast
Great Lakes
Southern
Great Plains
Southeast
West Coast
Great Lakes
Southern
Great Plains
Southeast
West Coast
Great Lakes
Southern
Great Plains
Southeast
West Coast
Great Lakes

1.08
4.35
3.23
2.23

2.51
4.35
1.41
3.85

2.79
4.13
0.57
3.68

2.75
3.77
1.86
3.58

2.80
4.62
4.55
4.06

3.26
3.85
2.76
3.29

3.08
3.31
1.53
2.48

1.79
3.88
2.69
2.26

0.05
-1.20
-0.18
-1.07

0.94
0.95
0.07
-0.43

-0.10
0.28
0.44
-0.06

0.52
0.72
1.20
0.52

0.05
-1.35
0.34
-0.94

1.99
-0.15
1.02
-0.31

-0.09
0.29
0.24
0.72

0.34
-0.15
-0.63
0.76

1.68
-0.85
0.13
-0.50

1.17
0.81
-0.12
0.44

0.36
0.11
0.71
0.35

0.00
-0.28
1.34
0.95
                              17-20

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                                                           17-21

-------
                                              Climate Variability
Discussion and Conclusions

     The results of this study must be viewed in the context of
how well the model reproduces the present climate variability.
In general, the model produces more extremes than are observed.
It is suggested that this may be because the model fails to
account for feedback processes that would minimize variability.
For example, the conservation of groundwater limits the
occurrence of temperature extremes in summer, as some surface
energy is used for evaporation rather than heating the ground
surface.  The GISS model does not account for this.  This points
to the need to include physical processes in the GCMs that
particularly influence variability.

The NCAR Study

     In this study, Mearns et al. analyzed the first and
second moments (i.e., mean and variance) of climate variable time
series from selected empirical stations and those produced by
general circulation model (GCM) control and perturbed runs, first
to determine how faithfully the GCMs reproduce these measures of
the present variability and then to examine how the variability
will change in C02 perturbed cases.   This type  of research is
essential because the variability performance of a GCM not only
is relevant to the credibility of its forecasts but also serves
as a diagnostic of the validity of model physics, since it is the
physical processes within the model's structure that give rise to
climate variability.  By comparing the relative performance
(i.e., model versus observations) of various versions of the NCAR
CCM (i.e., versions with different physical parameterizations or
formulations), they help to determine what formulations may be
needed for forecasting certain measures of variability and how
much credibility to assign to those forecasts.

Methods

     This study used the output from control runs of three
different versions of the NCAR Community climate Model (CCM).
However, the version of Chervin (1986) is the primary one used
for comparison of observed and model control output (i.e.,model
runs to simulate the actual present-day climate), since it has
the longest time integration (20 years).

     The version of the CCMO(A) model used is documented in
Chervin (1986).  The CCMO is a spectral general circulation model
originally developed by Bourke and collaborators (Bourke, 1974;
Bourke et al., 1977), which has been modified by the
incorporation of radiation and cloud parameaterization schemes.

                              17-22

-------
Chapter 17
The model has a resolution for physical processes of
approximately 4.5* in latitude and 7.5* in longitude, and has
nine levels in the vertical.  This version includes an annual
solar cycle featuring identical, seasonally varying forcing each
year.  Identical forcing each year was accomplished by
prescribing for each month ocean surface temperatures and sea ice
distributions.

     The other two versions of the CCM used are the Washington
version of the CCMO(A) (Washington and Meehl, 1984), which
includes an interactive thermodynamic ocean and surface
hydrology, and the Dickinson version (Dickinson et al., 1986), a
version of the more sophisticated CCM1(B) containing a diurnal
cycle and a very sophisticated land surface package, the
Biosphere-Atmosphere Transfer Scheme (BATS).

     The same four regions of the United States were chosen for
investigation as were chosen for the GISS study: the Great Plains
(represented by three grid boxes), the Southeast, the Great Lakes
and the West Coast.  The locations of the grid boxes are
indicated on Figure 17-3.  Note that the NCAR model grids for the
Great Plains are further north than the GISS grid for the
southern Great Plains.

     Real data corresponding to each grid box were generated from
the average of six observation stations for time series of
temperature and precipitation.  Solar radiation and relative
humidity real data were taken from one Solmet observation station
located in each grid square.  Figure 17-3 shows the location of
all observation stations and grid boxes.

     Four variables deemed particularly relevant to climate
impact analysis were chosen for this analysis: daily mean
temperature, daily total precipitation, mean daily relative
humidity, and mean daily absorbed solar radiation.

Comparison of Observed versus Chervin Control Run

     Temperature

     Figure 17-4 displays the time series of daily average
temperature for modeled and observed data for the four regions
investigated.  The model successfully simulates the annual cycle
for the four regions, which represents the variability within the
year.  There are regional differences,  however.  In the Great
Plains region, the model annual range is slightly smaller than
that of the observed time series (Figure 17-4a), whereas in the
Great Lakes region (Figure 17-4b) the model annual range is

                              17-23

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                                                        17-25

-------
                                              Climate Variability
greater.  The least successful simulation is that for the
Southeast grid (figure 17-4c), where winter minima are too high
by about 8°C.  Note that in the Great Plains region, the model
falls slightly short of attaining the appropriate maximum
temperatures in summer.

     Solar Radiation and Relative Humidity

     Simulation of solar radiation ranges from very good (the
Great Plains region) to only fair at the Southeast where the
model consistently overestimated absorbed solar radiation during
all months.  The Chervin CCM is strikingly poor at simulating the
annual cycle of relative humidity at all four locations.

     Precipitation

     The Chervin CCM consistently overestimates precipitation,
although the seasonal cycle is well simulated in the Great Plains
region and the West Coast grid.  The authors do not know why the
model overestimates precipitation but speculate that it may
partially be a result of a precipitation parameterization
criterion of 80% relative humidity.

Variability Comparisons of the Chervin CCM

     Interannual variability of temperature is generally
underestimated by the Chervin CCM in all four regions.
Interannual variability of precipitation (i.e., relative
variability, the standard deviation relative to the mean) is
generally in reasonable agreement with observed data, although it
is occasionally overestimated.  This is a particularly
encouraging result for the credibility of predicting climate
changes given how inaccurate the control precipitation results
are in terms of absolute values.

     In terms of daily variance, model relative humidity tends to
be much less variable than observed values at all locations and
in most months.  Results for temperature for January and July
indicate that the Chervin model generally overestimates daily
temperature variance (on the basis of statistical tests on the
innovation variance, i.e., the variance that remains when the
effect of autocorrelation is removed).  Solar radiation daily
variance comparisons are not particularly interesting.

Intercomparisons of Three CCM Versions and Observed Data

     Given that all GCMs fail in certain respects to accurately
reproduce observed climate, Mearns et al. felt that it would be

                              17-26

-------
Chapter 17
useful to compare different model versions' simulations of
present-day climate to be aware of the possible ranges of errors
and to understand more fully the effect of model structural
differences.  The present-day climate runs of models
incorporating physics different from those of the CCMO(A) version
of Chervin (1986) investigated in the third section are compared.
Both the Washington and Dickinson runs consist of
3-year integrations.  Table 17-2 presents comparisons of annual
and seasonal mean conditions simulated by the three models and
observations for the Southeast (SE) grid.  Statistics of
interannual variability cannot be analyzed because there are too
few years of simulated data.

     There is considerable variability in how well the models
reproduce mean total precipitation for the SE grid, ranging from
the very good results of Dickinson's model, to the overestimation
of Chervin's model, the underestimation of Washington's model.
On the basis of mean annual and seasonal comparisons, no one
model is clearly superior to the other two in accurately
reproducing mean climate at the four locations.

     The Dickinson model also produced much lower daily
variability of temperature than the other two models or in some
cases, than the observations.  This result is graphically
illustrated in the temperature histograms (three models and
observed) for two key months for the SE grid (Figure 17-5).

     The reasons for these discrepancies have yet to be explored
in depth, but are likely related to different land surface
packages in the models.  A possible explanation for the lowered
daily temperature variability of the Dickinson model concerns the
more sophisticated surface energy balance used, which includes
consideration of soil heat capacity.

Control versus C0?  Perturbed Runs

     The authors included a preliminary analysis of changes in
precipitation and temperature, under a scenario of doubled C02,
using the output from Washington's control and doubled CO2 runs
for the four regions.  Interannual variability could not be
analyzed because the time series are too short.  However,
examination of daily variance of temperature is presented.
                              17-27

-------
                                              Climate Variability
Table 17-2.  Southeast Grid — Multicomparisons of CCM Model
             Version and Observed Mean Temperature and Total
             Precipitation Statistics (Mearns et al.)
                              Obs.
Chervin
Wash.
Dick.
   Annual

Mean T (°C)                   16.6      20.0      20.1      21.5
Total precipitation (mm)    1137.2    3085.5     589.1    1401.8

   Winter

Mean T (*C)                    7.4      14.1      14.8      16.0
Total precipitation (mm)     738.9     295.3     393.4     293.2

   Summer

Mean T (°C)                   25.5      25.9      24.2      26.6
Total precipitation (mm)     317.0     786.4      75.7     346.9
Obs. = Observations.
Chervin- = Chervin CCM version (20-year run).
Wash. = Washington CCM version (3-year run).
Dick. = Dickinson CCM version (3-year run).
                              17-28

-------
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                                              Climate Variability
     As would be expected, an annual temperature increase of
about 2 and 3°C occurs at all locations.  Annual total
precipitation increases between 22 and 26% at three locations but
decreases slightly (2%) at SE.  There are also potentially
important changes in the seasonal distribution of precipitation.
For example, at the Southeast grid a smaller percentage of the
annual total occurs during the summer in the CO2 perturbed case
(from 13% to 6%).

     Statistics comparing daily temperature variance of the
control and perturbed runs for January,  April, July, and October
indicate that the temperature variance in general does not
significantly change (at the 0.05 level of significance) at these
four grids.  Without consideration of statistical significance
levels, results are mixed with both increases and decreases.

     Percentage of rain days decreases in the summer under
climate change in three of the four grids.  Interestingly, the
occurrence of small precipitation amounts decreases in the summer
in the perturbed case for the Southeast grid.


COMPARISON OF GISS AND NCAR RESULTS

     It is difficult to compare the two studies.  The modeling
experiments were conducted partially with different purposes in
mind using two different models (which differ not only in how
physical processes are modeled but also in their spatial
resolutions).  They also use different qualitative and
statistical methods for making comparisons.  The GISS experiment
was aimed primarily at examining the changes in variability with
climate change, whereas the immediate purpose of the NCAR
experiment was primarily to examine and explain discrepancies in
variability between model control runs and observations.  Since
the spatial resolutions of the models differ, the grid boxes of
the models do not coincide and so the regions analyzed differ.
These are only some of the problems that would affect these
comparisons.  Nevertheless, an attempt is made here to compare
some of their results that roughly coincide.  Some regions
coincide fairly well (such as the Great Lakes grids, see Figures
17-1 and 17-3), and some similar analyses were conducted.

     First a brief comparison is made of how the models reproduce
the observed mean climate.  In general,  the GISS model is too
cool and the NCAR model(s) too warm.  Precipitation is
overestimated at two grids by the GISS model and is overestimated
at all grid boxes by the Chervin version of the NCAR model
(although this is not true of two other versions of the NCAR
CCM) .

                              17-30

-------
Chapter 17.
     The following sections compare the observed and control runs
of interannual and daily variability of temperature and
precipitation, and then comparisons of climate change
variabilities are made.  It must be emphasized again that
comparison of control runs with observed data is an essential
step in the process of trying to evaluate the models' forecasts
of climate change.

Interannual Variability

     The easiest and most straightforward comparison can be made
of the two studies' results for interannual variability of
temperature and precipitation control runs.  Relative variability
values (standard deviation relative to the mean) for the GISS
study were provided by its authors (Rind, personal
communication).  Rind et al. use a 100-year control run for
interannual variability calculations.  Their observational data
set consists of 30 years (1951-80).  The NCAR study uses a 20-
year control run of Chervin (1986) and a 20-year observational
data set (1949-68).  The differences in sample size should be
noted.  Table 17-3a and 17-3b present the relevant results,
winter and summer standard deviations for temperature, and annual
coefficients of variation (i.e., a measure of relative
variability) for precipitation for the four regions for both
studies.   The overlap for the GISS southern Great Plains grid box
and the NCAR Great Plains III grid (see Figures 17-1 and 17-3) is
considerably less than in the case of the other three regions
(Great Lakes, Southeast, and West Coast).  In comparing the model
temperature standard deviations with the observed for each study,
there is little agreement in the direction of error from model to
observed.  Both models overestimate the variability of the Great
Plains region in winter.  (However, the difference in the NCAR
study was deemed statistically insignificant.)  Both models
underestimate the temperature variability (but the NCAR model
much more so than the GISS)  for the West Coast winter.  In all
cases the GISS study shows an overestimate and the NCAR study an
underestimate by the model,  of variability.

     Regarding the relative variability of precipitation, the
results for the two models are rather similar, although the GISS
values tend to be absolutely higher.   The differences between
observed and model values are very close (from 1 to 6 percentage
points) in each study.  The NCAR model slightly underestimates
the variability at each location, whereas the slight errors in
the GISS results are mixed.
                              17-31

-------
                                              Climate Variability
Table 17-3.
             Interannual Standard Deviations.   Temperature and
             Precipitation,  GISS and NCAR Control Runs (Rind,
             personal communication and Mearns et al.)
Temperature CO

a. GISS
(n = 100)
SGP Model
Obs
SE Model
Obs
WC Model
Obs
GL Model
Obs
b. NCAR
(n = 20)
GP III Model
Obs
SE Model
Obs
WC Model
Obs
GL Model
Obs
Dec . -Feb .

1.65
1.20
1.65
1.65
1.35
1.45
1.35
1.50

1.3
1.1
1.0
1.8
2.2
1.6
0.8
1.45
June-Aug .

1.05
0.75
1.05
0.70
1.35
0.75
1.25
0.70

0.14
1.2
0.38
0.74
0.71
0.88
0.17
0.81
Precipitation
Annual ( % )

15
21
22
18
18
23
18
18

17
22
10
12
10
11
17
17
SGP = Southern Great Plains; SE
GL = Great Lakes.
                                  Southeast; WC = West Coast;
                              17-32

-------
Chapter 17
    The reasons for the lack of agreement in the two studies are
far from obvious, and speculation can only be rough. Certainly
the difference in how the atmosphere ocean interaction is modeled
may play a role (i.e., the NCAR model uses fixed sea surface
temperatures, whereas the GISS model computes sea surface
temperatures from a simple ocean mixed-layer model),  In fact,
the number of differences in the two studies largely precludes
any straightforward analysis of discrepancies.

Daily Variability

    Daily variability of temperature can be compared for two
season months (January and July) at the four locations using the
standard deviations (Table 17-4).  Each study also examines
changed daily variability using some other statistical measure
(chi-squared test of distribution similarities in the GISS study
and innovation variance comparison in the NCAR study), but these
are not comparable.  Comparisons on the basis of standard
deviations alone cannot be statistically tested because of
problems encountered in meeting the assumptions required for the
tests, (although in a later version Rind et al. does apply tests
to the standard deviation after correcting for dependence in the
sample size).  Hence,  these comparisons must be viewed strictly
qualitatively.

    In seven of the eight cases, the studies agree  (that the
model overestimates daily temperature variability).  In the case
where there is disagreement (Great Plains, July), the NCAR
difference is not statistically significant on the basis of tests
on the innovation variance (the variance after the effect of
autocorrelation is removed).   However, the GISS discrepancy is
fairly large, suggesting that there is an overestimation by the
GISS model.  Still, the overall agreement is that the models tend
to overestimate daily variability at these four locations.  This
tendency is graphically illustrated in Figures l7-6a and 17-6b,
where the observed and model histograms of daily temperature for
April at the Great Lakes (GL)  grid for the two studies are
compared.

     In both studies,  explanations for the overestimations are
related to the modeling of surface hydrology, i.e., that both
models fail to completely account for important surface-
atmosphere interactions that would tend to reduce daily
temperature variability.
                              17-33

-------
                                              Climate Variability
     Table 17-4,
Daily Temperature Standard Deviations (°C)
(Rind et al.  and Mearns et al.)
                        GISS
                    Obs.    Model
                               NCAR
                           Obs.    Model
  January

Great Plains
Southeast
Great Lakes
West Coast

   July

Great Plains
Southeast
Great Lakes
West Coast
  4.81
  4.53
  4.97
  3.63
  1.74
  1.50
  2.38
  2.40
8.15
6.90
5.79
5.86
2.56
2.34
3.02
3.56
4.81
5.41
5.5
4.1
2.90
1.55
2.67
2.18
 8.15
 5.92
11.20
 5.0
 2.79
 1.70
 2.82
 3.52
                              17-34

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-------
                                              Climate Variability
     Daily variability of precipitation is compared by summary
statements made in the two studies for the four locations for
four seasons.  In general, the models produce,  in the majority of
cases, too few light rain days.  The GISS model produces too many
extreme rain events in winter at all locations.  The NCAR model
tends to produce too many high extremes in all  four seasons.
Neither study accounts for these discrepancies.

Comparison of Climate Change

     Comparison of climate change results of the two models is
restricted to changes in daily temperature variance for four
months for the four locations, since the NCAR study includes a
quantitative analysis of only temperature variability change.
The two studies do not agree on the direction of change of daily
temperature variability.  The NCAR results are  mixed showing both
increases and decreases, although most of these changes are
statistically insignificant.  Rind et al. conclude that in
general, there is a decrease in daily temperature variability on
the basis of changes in standard deviations (but the changes are
not statistically significant).  On the basis of the two research
reports, no clear statement may be made about changes in daily
temperature variability under C02  warming conditions.

Limitations of the Two Studies

     It should be noted that both studies underline the
importance of viewing climate change results of the models in the
context of how well they reproduce the present  climate.  Model
deficiencies can be expected to limit the reliability climate
change results, and that faith in quantitative  results are
probably misplaced.  However, model results give crude estimates
as to the importance of physical processes responsible for
variability and what must be done to improve them.  There is a
need for further testing to determine how the models'
deficiencies in reproducing present-day climate affects
predictions for a CO^-warmed future climate.


IMPLICATIONS FOR STUDIES OF CLIMATE CHANGE IMPACTS

     As indicated in the second section of this chapter,
virtually all systems are affected by climate variability,
although some more than others.  The relative importance of
climate variability and changes in variability, as a result of
climate change, to particular impact areas is reflected in the
results and limitations of some of the studies  summarized in this
report.

                              17-36

-------
Chapter 17
     Of greatest concern was the lack of information regarding
changes in the variability of temperature and precipitation that
would attend climate change.  The lack of this information
resulted in the formation of climate scenarios wherein the
temporal variability of both precipitation and temperature were
not changed (see Chapter 3 on scenario development).  This was
considered a limitation or concern in many studies, some of which
are discussed below.

     In the Johnson et al. study on agricultural runoff and
leaching (reviewed in Chapter 10, Agriculture), the results were
considered to be limited by the failure to consider changes in
storm frequency and duration that would result from climate
change.  Such changes would obviously affect the results of the
Pesticide Root Zone Model (PRZM), which determines the
distribution and transport of pesticides in soils.  Also, the
frequency of precipitation was left unchanged from the
present-day climate and, hence, estimates of total annual erosion
could be underestimated.  Furthermore, the magnitude of extreme
rainfall events could be exaggerated, since the number of days of
rainfall is not changed, but different (usually larger) amounts
of rainfall are assumed.  This could result in overestimation of
pesticide losses through soil erosion and leaching in a
particular year.  The results of this study could be vastly
different from those presented, depending upon assumptions
concerning precipitation duration, frequency, and intensity, all
of which would change if a changed daily variability were
assumed.

     Several studies on hydrology summarized in this report also
are highly dependent upon assumptions about precipitation
variability.  These include the Lettenmaier et al. study on the
hydrology of catchments in the Central Valley and the Sheer and
Randall study on the impact of climate scenarios on water
deliveries, both reviewed in Chapter 6.  The hydrologic inputs
for the models used in these studies are interdependent.
Lettenmaier et al. assumed that the number of days of rainfall
remains the same under the climate change.   Model results in
terms of predicting runoff amounts would be quite different if
more rainfall events of lower intensity were assumed compared to
the same number of rainfall events with (generally) higher
intensity.   Since the Sheer and Randall study uses the output of
the Lettenmaier study as hydrologic inputs to their water
delivery model, their results are also dependent upon the
assumptions about unchanged variability and,  hence, their results
could also change considerably if precipitation variability
changes were considered.


                              17-37

-------
                                              Climate Variability
     The studies for the Southeast (Chapter 6)  did not consider
changes in the frequency of droughts or severe storms such as
hurricanes, which could certainly affect the likelihood of
flooding for some coastal communities.  However, these concerns
are considered secondary to changes in sea level that would
dominate in terms of changing the likelihood of floods.

     Crop yields are very dependent on daily variability.  For
example, heat waves during grain filling lower wheat yields.
Whether a drought occurs early or late in the growing season has
differential effects on yields.  Changes in variability were not
considered in the Rossenzweig, Peart et al., Ritchie, and Dudek
studies.

     Changes in the frequencies of extreme events are considered
to be of great importance to potential forest disturbance, as
discussed in Chapter 11.  Here, an important distinction is made
between the ability of forests to adapt to changes in mean
climate conditions versus changes in extremes.   The possibility
of increases in the frequencies of events such as wind, ice, or
snow storms, and droughts and flooding may be of greater
significance to forest survival than the gradual mean change in
climate that has been studied so far.

     The Kalkstein study, which is reviewed in Chapter 14 on
Human Health effects,  is strongly dependent upon the
determination of certain maximum temperature threshold values
beyond which human mortality increases.  In applying the
death/weather effects statistical models to scenarios of climate
change, temperature variability is held constant, so that
temperatures that exceed the threshold values are determined
unrealistically.  Of course, there is greater accumulation beyond
the thresholds in the warmer scenarios, but not to the same
extent as would be the case if the both variance and mean of the
series are changed.  This problem is. explicitly stated in the
section on limitations.

     Changes in the variability of temperature both seasonally
and daily are important to studies concerned with the effect of
temperature change on the change in electricity demand discussed
in Chapter 16.  Although new generating capacity requirements for
the nation for 2010 and beyond are calculated assuming climate
change, the numbers generated could be considerably different for
any particular year depending mainly on air-conditioning needs,
which would be the major use increase for electricity.  Such
needs are sensitive to extremes in daily maximum temperatures and
the persistence of such temperatures (i.e., heat waves).


                              17-38

-------
Chapter 17
Potential change in extreme events is identified as a research
need in this chapter.

     It would be impossible to quantitatively or even
qualitatively estimate how different the results of these studies
would be if changes in climate variability had formed part of the
climate scenarios made available as input for the various climate
impact models used.  Primarily, it is impossible because the
variability changes are not known; second, it is impossible
because most of the studies are of such complexity that the
effect of a change in one variable (a complex change at that) is
not intuitively obvious in most cases.  Sensitivity analyses of
the impact models involved to changes in variability would be
required to provide specific answers.  What can be said at this
point is that the lack of information on climate variability has
limited a number of studies in this report and has limited the
completeness of the answers they could provide.  The magnitude of
change of some impacts could be affected by the inclusion or
exclusion of variability information.


FUTURE RESEARCH NEEDS

     The research reported above clearly indicates that research
of changes in climate variability with climate change is truly in
its infancy.  Much needs to be done.   Future research needs may
be broken into three categories.

     1.   Further investigation of variability in presently
          existing GCM control and perturbed runs.  Results
          summarized here represent only an initial effort at
          looking at variability in GCMs.  The first research
          priority is to examine at many more grid boxes the
          daily and interannual variability of many climate
          variables in addition to temperature and precipitation,
          such as relative humidity,  solar radiation, and severe
          storm frequency.  Moreover, the most sophisticated
          statistical techniques must be used or where needed,
          developed, such that uniform quantitative indicators
          are available to evaluate both how well the current
          models reproduce present variability and how they
          forecast the change in variability under climate
          conditions.  The causes for discrepancies in
          present-day climate variability and control run
          variability must be better understood,  so that a
          clearer understanding of future climate changes can be
          attained.
                              17-39

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                                    Climate Variability  ^
Improvements in GCMs geared toward better reproduction
of climate variability.  From the results of Rind et
al. and Mearns et al.,  some indications are given that
oversimplifications in the land surface packages of
GCMs contribute to overpredictions of daily temperature
variability.  This possibility is further underlined by
the better results obtained with Dickinson's model,
which includes a more sophisticated land surface
package.  More detailed analyses of current GCMs are
necessary to confirm this speculation as well as to
determine the causes of other errors in variability
such as for precipitation.  The next step involves
altering the GCMs so that variability is properly
simulated.  Only then can much faith be put in GCM
forecasts of variability changes with a perturbed
climate.

Sensitivity analyses of climiate change impact models
to changes in climate variability.  It also must be
determined how important changes in variability will be
to different areas of impact.  Since the variability of
climate variables produced from GCMs cannot be
"trusted" or even easily analyzed at this point, these
sensitivity analyses of impact models should be
performed with statistically simulated time, series of
climate variables, as has been performed by Schwarz
(1976) and Mearns et al. (1984).  By simulating time
series, different levels of autocorrelation and
variance in the time series may be controlled for and
systematically varied.   By this means, important
thresholds of variability change for different
variables as they affect the output of impact models
can be determined.  Moreover, ranges of possible
impacts of variability change can be determined and can
serve as guides until better information is available
on how variability will change in a CO2-warmed world.
                    17-40

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Chapter 17
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statement of concern by the AMS.  Bulletin of the American
Meteorological Society 66(7):858-859.

Barbecel, O., and M. Eftimescu.  1973.  Effects of
agrometeorological conditions on maize growth and development.
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Bates, G.T., and G.A. Meehl.  1986.  The Effect of CO2
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Monthly Weather Review 114:687-701.

Becker, R.J., and R.A. Wood.  1986.  Heatwave.  Weatherwise
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Bourke, W. 1974.  A multi-level spectral model.  I. Formulation
and hemispheric integrations.  Monthly Weather Review 102:687-
701.

Bourke, W., B. McAvaney, K. Puri, and R. Thurling.  1977.  Global
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Bridger, C.A., F.P. Ellis, and H.L. Taylor.  1976.  Mortality in
St. Louis, Missouri, during heat waves in 1936, 1953, 1954, 1955,
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Chervin, R.M.  1986.  Interannual variability and seasonal
predictability.  Journal of the Atmospheric Sciences 43:233-251.

Chervin, R.M.  1981.  On the comparison of observed GCM simulated
climate ensembles.  Journal of the Atmospheric Sciences 38:885-
901.

Clark, R.A.  1987.  Hydrological design criteria and climate
variability.  In: Soloman, S.I., M. Beran, and W. Hogg, eds.  The
Influence of Climate Change and Climatic Variability on the
Hydrologic Regime and Water Resources.  International Association
of Hydrological Sciences Publ. No. 168.  Oxfordshire:  IAHS
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Coleman, J.E.  1988.  Climatic warming and increased summer
aridity in Florida, U.S.A.  Climatic Change 12:164-178.
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                                              Climate Variability
                                                                    i
Dare, P.M.  1981.  A study of the severity of the midwestern
winters of 1977 and 1978 using heating degree days determined
from measured and wind chill temperatures.  Bulletin of the
American Meteorological Society 62(7):674-682.

Dickinson, R.E., A. Henderson-Sellers,  P.J. Kennedy, and M.F.
Wilson.  1986.  Biosphere-Atmosphere Transfer Scheme (BATS) for
the NCAR Community Climate Model.  NCAR Technical Note 275, NCAR,
Boulder.

Ellis, F.P.  1972.  Mortality from heat illness and heat-
aggravated illness in the U.S.  Environmental Research 5(1):1-58.

Emmanuel, K.A.  1988a.  The dependence of hurricane intensity on
climate.  Nature 326:483-485.

Emmanuel, K.A.  1988b.  Toward a general theory of hurricanes.
American Scientist 76(4):370-379.

Gibbs, W.J.  1984.  The great Australian drought:  1982-1983.
Disasters 8/2/84 89-104.

Hansen, J., I. Fung, A. Lacis, S. Lebedeff, D. Rind, R. Ruedy, G.
Russell, P. Stone.  1988.  Global climate changes as forecast by
the Goddard Institute for Space Studies three-dimensional model.
Journal of Geophysical Research 93(D8): 9341-9364.

Heathcote, R.L.  1985.  Extreme event analysis.  In:  Kates et
al.  Climate Impact Assessment, SCOPE 27.  Chichester:  John
Wiley and Sons.

Henz, J.F., and Scheetz, V.R.  1976.  The big Thompson flood of
1976 in Colorado.  Weatherwise 29(5):278-285.

Herbert, P.J., and Taylor, G.  1979.. Everything you always
wanted to know about hurricanes.  Weatherwise 32(2):61-67.

Jones, T.S. et al.  1982.  Morbidity and mortality associated
with the July 1980 heat wave in St. Louis and Kansas City, MO.
Journal of the American Medical Association 247:3327-3331.

Kalkstein, L.S.  1988.  The Impact of C02 and Trace Gas-Induced
Climate Changes Upon Human Mortality.  Report prepared for U.S.
EPA, contract No. 68-01-7033.
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Chapter 17
Kalkstein, L.S., R.E. Davis, J.A. Skindlov, and K.M. Valimont.
1987.  The impact of human-induced climate warming upon human
mortality:  a New York case study.  Unpublished?  Pre-report for
the EPA.  26 pp.

Katz, R.W.  1984.  Procedures for Determining the Statistical
Significance of Changes in Variability Simulated by an
Atmospheric General Circulation Model.  Climate Research
Institute Report No. 48.  Oregon State University, Corvallis.

Linder, K.P., M.J. Gibbs, and M.R. Inglis.  1987.  Potential
Impacts of Climate Change on Electric Utilities.  New York State
Energy Research and Development Authority, Report 88.2  Debany,
New York.

Manabe, S., and D.G. Hahn.  1981.  Simulation of atmospheric
variability.  Monthly Weather Review 109:2260-2286.

McQuigg, J.D.  1981.  Climate variability and crop yield in high
and low temperature regions.  In: Back W., J. Pankrath, and S.H.
Schneider, eds. Food-Climate Interactions.  Reidel, 121-138.

Mearns, L.O., S.H. Schneider, S.L. Thompson, and L.R. McDaniel.
1988.  Analysis of climate variability in general circulation
models (in preparation).

Mearns, L.O., R.W. Katz, and S.H. Schneider.  1984.  Extreme
high-temperature events:  Changes in their probabilities with
changes in mean temperature.  Journal of Climate and Applied
Meteorology 23:1601-1613.

Mederski, H.J.  1983.  Effects of heater and temperature stress
on soybean plant growth and yield in humid temperature climates.
In:  Raper, C.D., and P.J. Kramer, eds.  Crop Reactions to Water
and Temperature Stresses in Humid, Temperate Climates.  Boulder,
CO:  Westview Press, pp. 35-48.

Mogil, H.M., et al.  1984.  The great freeze of '83:  Analyzing
the causes and the effects.  Weatherwise 37(6):304-308.

Neild, R.E.  1982.  Temperature and rainfall influences on the
phenology and yield of grain soybean and maize.  Agricultural
Meteorology 27:79-88.

Newman, J.E.  1978.  Drought impacts on American agricultural
productivity.  In:  Rosenberg, N.J., ed.  North American
Droughts.   Boulder, CO:   Westview Press,  pp. 43-63.


                              17-43

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                                              Climate Variability
Northwest Power Planning Council.  1983.  Regional Conservation
and Electric Power Plan 1983.  Portland, OR:  Northwest Power
Planning Council.

Oeschsli, F.W., and R.W. Buechley.  1970.  Excess mortality
associated with three Los Angeles September hot spells.
Environmental Research 3:277-284.

Oliver, J.  1981.  The nature and impact of Hurricane Allen -
August 1980.  Journal of Climatology 1:221-235.

Parry, M.L.  1978.  Climatic Change, Agriculture and Settlement.
Dawson, Folkstone.

Quirk, W.J.  1981.  Climate and energy emergencies.  Bulletin of
the American Meteorological Society 62(5) : 623-631.

Reed, D.N.  1986.  Simulation of time series of temperature and
precipitation over eastern England by an atmospheric general
circulation model.  Journal of Climatology 6:233-257.

Reibsame, W.E., and D.J. Smith.  1988.  Sensitivity and
adjustment to climatic fluctuation in water resource management.
Climatic Change (13) (in press).

Rind, D. , R. Goldberg,  and R. Ruedy.  1988.  Change in climate
variability in the 21st century.  Submitted to Climate Change.

Rosenberg, N.J., ed.  1978.  North American Droughts.  Boulder,
CO:  Westview Press.

Rosenberg, N.J. (ed) „  1979.  Drought in the Great Plains:
Research on Impacts and Strategies.  Water Resources
Publications, Littleton, Co.

Sanders, J.F.  1982.  The hurricane dilemma.  Weatherwise
35(4) :174-178.

Schugart, H.H., M. Ya.   Antonovsky, P.G. Jarvis, and A. P.
Sandford.  1986.  C02,  climatic change,  and forest ecosystems.
In Bolin, B. , B.R. Doos, J. Jager and R.A. Warrick (eds.), The
Greenhouse Effect, Climatic Change, and Ecosystems.  SCOPE 29,
John Wiley and Sons, Chichester, U.K. pp. 475-521.

Schwarz, H.E.  1977.  Climatic change and water supply:  How
sensitive is the Northeast?  In:  Climate, Climate Change and
Water Supply.  Washington, DC:  National Academy of Sciences, pp.
111-120.

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Chapter 17
Shaw, R.H.  1983.  Estimates of yield reductions in corn caused
by water and temperature stress.  In:  Raper, C.D., and P.J.
Kramer, eds.  Crop Reactions to Water and Temperature Stresses in
Humid, Temperate Climates.  Boulder, CO:  Westview Press, pp. 49-
66.

Soloman, A.M., and O.C. West.  1985.  Potential responses of
forests to CO2-induced climate change.   In:  M.R.  White,  ed.
Characterization of Information Requirements for Studies of C02
Effects:  Water Resources, Agriculture, Fisheries, Forests, and
Human Health.  U.S. Department of Energy, DOE/ER-0236.  pp. 145-
170.

Thompson, L.M.  1968.  Weather and technology in the production
of corn.  In:  Purdue Top Farmer Workshop, Corn Production
Proceedings.  West Lafayette, IN:  Purdue University, pp.
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Warrick, R.A., et al.  1975.  Drought Hazard in the United
States:  A Research Assessment.  University of Colorado, Boulder.
IBS Monograph No. NSF-RA-E-75-004.

Washington, W.M. and G.A.  Meehl 1984.  Seasonal cycle experiment
on the climate sensitivity due to a doubling of CO2 with an
atmospherice general circulation model coupled to a simple mixed-
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9503.

White, G.F. et al.  1975.  Flood Hazard in the U.S.A. Research
Assessment.  University of Colorado, Boulder.  IBS Monograph No.
NSF-RA-e-75-006.

Wilhite, D.A., and M.H. Glantz.  1987.  Understanding the drought
phenomenon:  The role of definitions.  In D.A. Wilhite and W.
Easterling (eds.), Planning for Drought.  Westview, Boulder,  pp.
11-27.

Wilford, J.N.  1988.  Vest Persistent Pattern Spreading Heat
Wave.  The New York Times, p. 1; July 19.

Wilson, C.A., and J.F.B. Mitchell.  1987.  Simulated climate and
C02-induced climate change over Western Europe.   Climate Change
10:11-42.
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                            CHAPTER 18

                          RESEARCH  NEEDS
     The Environmental Effects report has summarized the results
of over 50 individual research projects interpreted from regional
and national viewpoints.  As described in previous chapters, this
report is organized around a series of regional case studies
performed for the Great Plains, the Southeast, the Great Lakes
region, and north-central California, as described in Chapter 1.
In addition, several larger environmental issues, such as impacts
on agriculture, forest resources, coastal zones, and water
demand, were analyzed from a national perspective.  In each
regional and national study, an attempt was made to make use of
the highest quality and most recent science available.  This
process has resulted in two outcomes:

1.   The results provide insight about the sensitivities of
     different sectors and regions to climate change.

2.   The results themselves raise new scientific questions and
     issues that cannot now be resolved.  For example, the
     importance of certain climate data for impact analyses has
     been recognized.  The following partial list of examples may
     be helpful to circulation modelers:

     o    the importance of winds in analyses of Great Lakes
          levels;

     o    the need for information on major storms and hurricanes
          to fully assess impacts on coastal regions;

     o    the role of water vapor, clouds, boundary layer, and
          windspeed and direction for air quality analyses;

     o    the impact of precipitation variability on pesticide
          runoff studies;

     o    the effect of changes in freezing conditions on ice
          cover in the Great Lakes and on snow pack in
          California;

     o    the importance of soil moisture and temperature on
          forest growth;

     o    the effect of temperature and precipitation variability
          on agriculture;
                              18-1

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                                                   Research Needs

          the role of water runoff for future estimates of
          hydroelectric power, flood control, and water quality;
          and

          the possible importance of synoptic weather patterns on
          health.
     This chapter summarizes the major scientific research issues
on the environmental effects of climate change that the
Environmental Protection Agency has identified while preparing
this report.  It is not our purpose to make recommendations to
the U.S. Government or to the full scientific research community.
However, we have, where appropriate, suggested areas where strong
research coordination should occur and have attempted to describe
where such research coordination is already occurring.

     Detailed research needs have been identified and justified
in each chapter.  Table 18-1 summarizes these research needs for
several major topics.  The assumption that underlies both this
table and the overall research strategy is that focusing on
regional-scale effects from global atmospheric change is an
effective way to address scientific issues relevant to
environmental policymakers.  This report has upheld that initial
assumption, and we expect that future research on impacts in
other parts of the globe and on other resources will do so as
well.  In addition, however, it will be important to understand
broad national consec[uences of the regional impacts of climate
change.  We propose that this can be accomplished by giving
careful attention to both aspects in research, and by conducting
scientific studies arid policy studies in close cooperation, as
has been done in this; report.

     This chapter contains four main sections:

     1.   A description of the research role that EPA will play
          in the U.S. Government's overall research program in
          global climate change;

     2.   A description of the main research thrusts to be
          pursued in the environmental consequences of global
          climate change;

     3.   A description of the supporting atmospheric science
          research that will be necessary from the standpoint of
          understanding environmental effects; and
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Chapter 18
     4.   A short summary of the research topics implicit in
          integrating regional and national-scale research issues
          in such a way that they are relevant to the development
          of environmental policy.
THE ENVIRONMENTAL PROTECTION AGENCY'S RESEARCH ROLE

     EPA's main responsibility is to develop, implement, and
enforce policies to protect human health and the environment.  In
recent years, the concept of risk assessment and risk-based
decisionmaking has been used as a model for developing policy-
relevant scientific information in a logical fashion that takes
into account the inherent uncertainties in data and understanding
(Ballou et al., 1981; Barnthouse et al., 1982; Harwell and
Harwell, 1988).  While this concept has its roots in health and
toxicological research and regulatory activities in EPA  (North
and Yosie, 1987), it can also be extended in concept to  other,
more ecological issues.

     Global climate change presents a challenge to this  concept,
as EPA, other Federal agencies, and international research
organizations have discovered.  Since probable losses due to
climate change cannot be quantified in a truly predictive
fashion, a strong research emphasis must be placed on scientific
assessment: we must identify not only what we do and do  not know,
but how well we understand the possible consequences of  change.
The role of EPA's research program and other research programs
should thus clearly be to provide understanding and scientific
assessments necessary to develop policy options and to analyze
their consequences for the environment.

     EPA and the U.S. Government are moving strongly in  this
direction.  The Global Climate Protection Act of 1987 directs EPA
and the State Department to coordinate the development of
national policy for global climate change.  This coordination
involves many other agencies with essential policy roles, such as
the Department of Energy.  In addition, the act directs  EPA, in
cooperation with other agencies,  to prepare a scientific
assessment of climate change with international scope and
representation.  EPA has been designing the scientific assessment
in cooperation with several Federal departments and research
agencies:  the National Aeronautics and Space Administration, the
National Oceanic and Atmospheric Administration, the National
Science Foundation, the U.S. Geological Survey, the Department of
Energy, the Office of Naval Research,  and the U.S.  Department of
Agriculture.  These agencies,  along with the State Department,
have been organized under the auspices of the Committee on Earth

                               18-3

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                                                   Research Needs

Sciences in the Office of Science and Technology Policy and in
cooperation with the National Climate Program Office.  The
scientific assessment will address the scientific information
that is important for policymakers to consider as they move
toward developing policy options.

     Within the U.S. Government, EPA's overall role encompasses
both policy development and scientific research.  In scientific
research, its main responsibility will be to understand the
potential consequences of global atmospheric change, the
anthropogenic contribution of global change and options to
minimize it, and the development of adaptation responses.

     That responsibility and the research in this report have led
to the formulation of several important scientific questions that
are also relevant to EPA's policy mission.  These questions
should be thought of as overriding themes, rather than as a list
of all the potential issues:

     o    What is the likelihood of a change in the global
          climate system, occurring over the next several decades
          to a century, that is clearly attributable to
          anthropogenic influences?

     o    How will climate and atmospheric chemistry change in
          different regions?

     o    What is the extent and magnitude of ecological and
          environmental change associated with changes in
          regional chemistry and climates?

     o    Over what time spans are regional atmospheric change
          and subsequent ecological changes likely to occur?

     o    What are the potential impacts of climate change on
          environmental resources?

     These policy-oriented questions are viewed as the beginning
stages for analyzing possible environmental changes resulting
from climate change and eventually analyzing the possible avenues
of managing risks.  They also define the specific areas in which
EPA will conduct and sponsor research, e.g., emissions of trace
gases, global atmospheric chemical modeling, regional atmospheric
consequences of change, regional environmental consequences of
change, and monitoring of sensitive ecosystems for change.

Goals and Objectives

     The major research goals and objectives of EPA's research
program have been structured to address the policy-oriented

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Chapter 18
questions.  They reflect the need to establish scientific
direction that is consistent with major policy uncertainties.  In
so doing, the goals and objectives are more technical statements
of research needed to address the policy questions.

     The goals of EPA's proposed research are the following:

     o    To assess the probability and magnitude of changes in
          the composition of the global atmosphere, and the
          anthropogenic contributions to those changes, for the
          purpose of evaluating the likelihood and magnitude of
          subsequent climate change.

     o    To assess the likely extent, magnitude, and rate of
          regional environmental changes as a function of
          variability in climate, for the purpose of evaluating
          the risks associated with changes in the climate
          system.

     Since this report has focused on the effects of climate
change, and not on the processes leading to climate change, we
will focus here on the second goal.  The following objectives
relate to this goal:

     o    To relate global scale changes in climate and chemistry
          to regional scale changes by constructing a series of
          regional atmospheric scenarios.

     o    To predict environmental responses to climatic
          variation and to test the processes that control those
          responses.

     o    To document the spatial covariation of regional climate
          change with regional ecological change to establish
          comprehensive ecological monitoring in selected
          locations,  cooperatively with other EPA and Federal
          programs.

     o    To produce periodic scientific assessments in
          conjunction with other Federal agencies and
          international research organizations,  and to perform
          research to evaluate the consequences of adaptation
          policies.
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                                                   Research Needs

ENVIRONMENTAL CONSEQUENCES OF CLIMATE CHANGE

Background

     The long-term goal of the environmental research proposed is
to create quantitative regional models of environmental responses
to climate change for decisionmakers.  These models need to
explain landscape-level and multi-resource interactions, e.g.,
links between air quality, forest health, and climate change,
that are beyond the scope of this report.  Before such models can
be created, however, many gaps in knowledge remain to be
addressed.

     Research still needs to be done that will (1) identify
regions and resources sensitive to global climate change;  (2)
establish quantitative, causal relationships between climate and
selected ecological indicators and attributes of concern;  (3)
predict the impact of changing climate on selected systems and
regions; (4) refine the assessments and methodologies to include
quantitative, multi-resource interactions; and (5) develop the
ability to address multiple stressors, integrated at the regional
scale.

     The process consists of four generic steps:

     o    Classify and characterize the environmental resources
          of concern;

     o    Determine the resources' current status, recent trends
          in condition, and possible associations with climatic
          variability;

     o    Use mathematical models to estimate future status under
          different climatic scenarios; and

     o    Characterize,the possible changes in each system by
          sensitivity studies, and by formally considering the
          uncertainty inherent in the mathematical models and
          underlying data.

Objectives

     In the first phase of research, one must continue to
identify resources and regions sensitive to climate change
through review and synthesis studies (e.g., NAS,  1982; MacCracken
and Luther, 1985; Trabalka, 1985; Bolin et al. 1986; Shands and
Hoffman, 1987; White, 1985).  These studies will proceed from the
identification of extant data through exploratory analyses and
model enhancement to regional characterizations of environmental
changes associated with global climate change.  The second phase

                               18-6

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Chapter 18
will build on the first to initiate experimental studies
investigating causal relations among climatic stressors and
ecological responses at the ecosystem, landscape, and regional
scales.  In the third phase, several years away, research should
emphasize trends detection, long-term experimental manipulation,
and model testing and refinement.  In each phase, close
cooperation with the U.S. land management and research agencies
will be necessary for success.

     The following objectives are identified for each of the
above phases.

Short-Term Objectives

     o    Define environmental sensitivity qualitatively, and
          identify sensitive climatic, biotic, and aquatic
          regions for study using extant data.

     o    Produce conceptual models of expected climate-induced
          responses, including changes in biogenic sources of
          radiatively important trace gases.

     o    Prioritize the regions and systems, as well as the most
          appropriate temporal and spatial scales, for in-depth
          observational and experimental (field and laboratory)
          studies.

Mid-Term Objectives

     o    Establish quantitative, causal relationships between
          climate and selected environmental attributes of
          concern, and begin to quantify the uncertainties.

     o    Proceed from qualitative to quantitative, predictive
          models.

     o    Produce preliminary predictions of changing climatic
          impacts on selected systems and regions, and quantify
          the uncertainties.

Long-Term Objectives

     o    Refine the assessments and methods produced in the
          first two phases to include quantitative,
          multi-resource interactions.
                               18-7

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                                                   Research Needs

     o    Develop and validate capabilities to address multiple
          stressors and resources, integrated at regional scales
          for decisionmaking.

Research Strategy

     This report has clearly shown that concerns over the
adaptability and fate of natural ecosystems are well founded.
Forested ecosystems, aquatic and marine biota, wildlife in
refuges, water quality in small lakes, and certainly other
resources may be unresistant to rapid climate change.  The
strategies for mitigating changes in these systems are likely to
be large and exceedingly difficult to implement.  Consequences
for environmental attributes such as biodiversity, primary
productivity, and cycling of nutrients, while difficult to
quantify, may be equally difficult, if not impossible, to
reverse.  Federal agencies with both stewardship and research
responsibilities for managing natural resources such as the U.S.
Forest Service, the National Park Service, the Fish and Wildlife
Service, the U.S. Geological Survey, the Bureau of Land
Management,  and the National Oceanic and Atmospheric
Administration, should recognize that data, models, and continued
research on these environmental resources and attributes are
vital.  This report has additionally shown that while intensively
managed ecosystems, especially agroecosystems, may also be
affected by a climate change, there seem to be more opportunities
for human intervention to mitigate or adapt to the response.
Thus, the critically important questions become whether or not
the capacity for human intervention can keep pace with the rate
of change induced by changing climate.  Areas of major interest,
therefore, are historical changes in the distribution and yield
of agroecosystems as a function of climate, interactive effects
of climate change and carbon dioxide increases on crop yields,
and the adaptation rate of management practices.  The
Agricultural Research Service and Department of Energy have been,
and should continue to be, important contributors to these
research areas.  Whether the same generalizations will hold for
agriculture abroad remains to be investigated, and EPA will
cooperate with U.S. and international organizations to explore
this issue further.

     Other managed environmental resources, such as air and water
quality, or the preservation of coastal wetlands, are already
subject to regulation, but may well be sensitive to climate
change, as shown in Chapters 8, 9, and 13.  EPA will investigate
the possible consequences of climate change for these resources,
examine their influence on ecosystems, and analyze the
implications for regulatory policies.  Other already regulated
resources, such as drinking water and groundwater, may also be
investigated.

                               18-8

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Chapter 18
     Possible impacts on human health, as emphasized in this
report, are both troubling and very difficult to quantify.  The
correlative studies reported in Chapter 14 need to be
substantiated with more targeted research on the mechanisms of
impact.  While EPA is not likely to be a major contributor in
this area, other organizations, such as the National Institutes
of Health or the National Institute for Environmental Health
Studies, may be logical sponsors for further research.  The
possibilities that disease vectors may change their distributions
as a function of climate change, while speculative, should be
pursued more completely.  To the extent that these are as much
ecological questions as they are health questions, contributors
will include EPA as well as organizations such as the Centers for
Disease Control.

     It is clearly not possible to study all potential effects.
Because of the concerns raised in this report, and EPA's
responsibilities for understanding the consequences of climate
change, initial focus will be on the possibilities of
irreversible change as well as when changes may occur rapidly.
Therefore, early work will concentrate on providing data on the
sensitivities of environmental systems to climate change,
constructing conceptual models, and providing input to future
regional and national-scale assessments.  Later research will
lead to increasingly quantified understanding of environmental
response to climate change in several research areas: regional
environmental attributes, feedbacks, scaling issues, disturbance
regimes, and landscape interactions.

     To conceptually organize research, attributes of systems
will be investigated as a function of ecological and biotic
regions (Solomon and West, 1985; Braun, 1950; Brown and Lowe,
1980; Fowells, 1965; Vankat, 1979; Wells, 1979).  Then the
structural and functional aspects of each attribute will be
investigated.  Ecosystems and regions will be defined by extant
environmental conditions and existing data, with boundaries along
maximum rates of change in system attributes.  Ecosystems and
regions will therefore be well defined near the center of their
range or distribution.  The boundaries will necessarily be less
well defined, but they will be more precisely delineated as a
function of continuing analyses.  Examples of similar approaches
to resource definition are shown in Figures 18-1 through 18-3.

     The different scales of spatial patterns on the ground can
impart great difficulties in the "scaling up" of local processes.
Therefore, a high priority is to develop the ability to
interpolate from large spatial scales to small and extrapolate
from local patterns and processes to regional generalizations.

                               18-9

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           BAILEY'S ECOREGIONS FOR
               NEW ENGLAND AND
           THE MID-ATLANTIC STATES
                                      ECOREGION KEY
                                     Bi NORTHERN HARDWOODS
                                     •i N. HARDWOOD-SPRUCE
                                     -Ji BEECH-MAPLE FOREST
                                     • APPALACHIAN OAK
                                       SOUTHEASTERN MIXED
Figure 18-1.


Source:
Bailey's ecoregions for New England and the Mid-
Atlantic States.
                       18-10

-------
           KUCHLER'S ECOREGIONS FOR
                 NEW ENGLAND AND
               .HE 1^ ilD-ATLANTIC STATES
                                        ECOREGION KEY
                                       E3 NE SPRUCE-FIR
                                       -J BEECH-MAPLE FOREST
                                       -~J MIXED MESOPHYTIC
                                       • APPALACHIAN OAK
                                       •I NORTHERN HARDWOODS
                                       •i NE HARDWOOD-SPRUCE
                                       E3 NE OAK-PINE
                                         OAK-HICKORY-PINE
Figure 18-2.
Source:
Kuchler's ecoregions for New England and the Mid-
Atlantic States.
                         18-11

-------
                                   Biotic Regions

                                   EWc3 west Co«st
                                   feNwj Northwest
                                   f'Qbij Great Basin
                                   F?w3 Southwest
      Central and
      Southern Rockies
      Short Grass
f=^=\ Tall Grass
f-NhH N. Hardwoods
                                      3 S. Hardwoods/Pine
                                        Subtropic
 :.Tj>:j Taiga
  T I Tundra
                                        Eastern Deciduous
                                        Forest
Figure 18-3.    Major biotic regions of the United States.
Source:   Compiled  from Braun (1950); Fowells  (1965) ;  Vankat
            (1979) ; Wells  (1979);  Brown and Loew  (1980),
                                  18-12

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Chapter 18
Intercalibration of measurement approaches will improve
confidence in results and should allow low-cost regional
estimates from satellite measurements.  The National Science
Foundation, the National Aeronautics and Space Administration,
and the National Oceanic and Atmospheric Administration will be
key contributors to this research.  However, a significant
investment in methods development of sensors as well as
ground-truthing must be done before this goal becomes a reality.
Analysis of the effects of changes in climatic variability is
critical to understanding potential environmental changes.
Variations in the frequency of weather events are important for
many environmental processes, and the rates of those processes
may vary as a function of both spatial scales and temporal
scales.  Changes in climatic variability will be critical as the
problem to be addressed becomes one of attempting to predict the
occurrence of large-scale, rapid changes in the biosphere.

     Critical feedbacks in ecosystem distributions result from
(1) interactions between bordering systems, such as the
forest-prairie ecotone; (2) differential lags, such as the
different migratory and developmental rates of different kinds of
organisms and physical components within any given system; (3)
interactions between biogeochemical processes and population
processes; and (4) boundary layer effects.

     The differing lifespans and dynamic processes in the
soil-plant-atmosphere continuum create lags that will cause the
response time of systems to differ substantially from the rate of
climate change.  Changes in the biogeography or distribution of
species will change biogeochemical balances, which will then
change the size of reservoirs of carbon and other elements, thus
changing the rates of production of some radiatively important
trace gases.

     Physical and biological disturbances on any scale exercise
considerable influence over the patterns and processes of
ecological systems on both larger and smaller scales.  Frequency,
extent, and magnitude of disturbances will likely change as a
function of global climate changes.  The relationships between
disturbances and ecological responses will therefore be critical
to any modeling that attempts to predict the appearance and rate
of change of large areas of landscape.

     The initial stages of research should involve the following:
(1) setting priorities for systems and regions,  based on initial
concepts of sensitivity and results from studies in this report
and others; (2) constructing conceptual models;  and (3)  providing
preliminary information for national-scale assessments of

                              18-13

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                                                   Research Needs

environmental effects of climate change.  The major indicators of
regional sensitivity to be used should include natural
variability of weather and concomitant variability in the growth
and distribution of major plant species, based on historical
records and proxy data.

     Early scientific assessments should provide information on
(1) location of sensitive regions, and (2) conceptual models that
include causal processes.  To evaluate the potential sensitivity
of regions, landscapes, and ecosystems, the temporal variability
in the spatial distribution of both weather patterns and
ecological resources must be analyzed systematically.  This is
difficult, because increased resolution on one scale generally
results in decreased resolution on the other.  However, the
results will provide the conceptual models of regional responses
to global climate change.  A similar approach is applicable to
aguatic biota and water resources, wetlands, agriculture, and
.other environmental resources.

     The general procedure is to identify climatic regions, as
determined by both temporal (seasonal) and spatial variability in
weather patterns (Borchert, 1959; Bryson, 1966; Mitchell, 1969;
Wendland and Bryson, 1981).  Climatic regions so identified are
then associated with attributes of corresponding environmental
and ecological systems that might be sensitive to these changing
weather patterns.  The zones of seasonal weather patterns and
interannual variability can then be analyzed for covariation with
corresponding data on major natural resources, such as vegetation
distribution and growth  (Braun, 1950; Powells, 1965; Vankat,
1979; Wells, 1979; Brown and Lowe, 1980).  Characteristics of the
plant distributions, specifically species boundaries or
transition zones, are related through causal hypotheses to
variability in weather patterns.  These characteristics and model
results are then used to indicate the expected future covariation
between climatic and natural resources regions, ecotonal areas,
and ecosystems potentially sensitive to large-scale shifts in the
climate system.

     The critical areas to be identified during these analyses
include (1) links between indicators of climate change and upper
atmospheric weather patterns; and (2) links between upper
atmospheric weather patterns, surface weather patterns, and
resource variability (Neilson, 1986); thus providing (3) links
between indicators of climate change and resource variability.
This information can then be integrated to evaluate the expected
responses in resource indicators to a change in the climate
system.  The entire process yields mechanistic, conceptual models
of regional ecosystem responses to global climate change.
                              18-14

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Chapter 18
     This approach can also be used to identify potentially
susceptible water resources and surface water regions of the
country (Figure 18-4) (USGS, 1986).  This will produce a
depiction of the processes that control seasonal runoff patterns
and their year-to-year variability, as well as a direct
relationship between rainfall and runoff at a regional scale.
The interactions between regional rainfall, runoff, vegetation
cover, soil moisture, and evapotranspiration will then need to be
addressed.  Integrating hydrologic flows, land-use patterns, and
ecosystem dynamics will allow characterization of water quality
patterns within regions.  These associations can then be used to
characterize the effects of climate change on water resources on
regional spatial scales.

     The biotic and hydrologic studies then must be integrated to
identify regions and sites for future experimental study.  This
is critical as terrestrial, aquatic, wetland, and coastal systems
do not exist in isolation; their interactions affect each
ecosystem both directly and indirectly.

Experimentation. Modeling, and Monitoring

     Field and laboratory experiments will be required to address
directly some of the proposed mechanisms and ecological processes
that mediate landscape and regional scale responses.
Experimentation will assist in model development, model
calibration, and identification of baselines against which change
can be measured.

     Experiments and observations should assess quantitatively
the changes in resources as a function of position along regional
environmental gradients.  Attributes to be assessed include (1)
past variability of resources to climate change; (2)
establishment and mortality of plant species; (3) decomposition
and productivity patterns; (4)  successional and biodiversity
patterns; (5) biogenic emissions of trace gases; and (6)  runoff
and water quality patterns.

     Monitoring studies must be initiated for the purposes of (l)
resolution of ecological patterns at different temporal and
spatial scales; (2)  regional detection of trends; and (3)
calibration and validation of models.  The locales, systems, and
attributes to monitor should be based on the extant data analyses
and field studies outlined above.

     Modeling experiments should be performed to reduce
uncertainties in our capabilities to predict ecological
responses.  Sources of uncertainties include (1) dispersal

                              18-15

-------
                                      Water-Resource Regions



                                            New England       tflTWil Arkansas-White-Red



                                      fo02)3 Mid-Atlantic       t (i 2"J J| Texas-Gulf



                                      £763)3 South Atlantic-Gulf  |!i(13J:il Rio Grande
                                      ••MV**F«M                    t*Mfti*44j


                                            Great Lakes       £(14^ Upper Colorado



                                          V3 Ohio             ^(15^ Lower Colorado
                                             (16)q Greet Bavin



                                                  Pacific Northwest
                                            . ^
                                        (O6K Tennessee



                                             Upper Mississippi



                                        (06).] Lower Mississippi



                                         O9)  Souris-Rad-Rainy



                                             Missouri
                                             (18); California
                                              2oHawaM
Figure  18-4.
Water resource management  regions based  on Water

Resources Council  and  USGS delineation.
Source:   USGS (1986).
                                    18-16

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Chapter 18
through a heterogeneous and changing landscape; (2) lags imparted
by life cycles of dominant organisms and ecological processes;
(3) rate changes imparted by feedbacks from direct effects of C02
on plant processes;  (4) landscape transfers of sediment,
nutrients, organic matter, energy, water, and propagules among
terrestrial, aquatic, wetland, and near-coastal systems; (5)
geomorphic processes; and (6) possible threshold effects or
synergistic effects  in any of these processes, including the
possibility of exotic or weedy species overrunning newly created
habitats.

     The modeling strategy will be most effective in a phased
approach, focusing initially on developing conceptual models and
critically assessing already available techniques and
quantitative models.  This report has begun to contribute to this
phase due to its use of existing models for analysis.  Components
of existing models will then be evaluated for use in regional
models or for direct application.  Conceptual models will then
provide a framework  for integrated landscape and regional
simulation models.  Modeling exercises should initially parallel
the field experiments outlined above.

     Mid-term research tasks will be a direct outgrowth of
earlier work and also will address major feedback loops and
quantifying temporal and spatial scale relationships.

     The feedback loops fall into three general categories: (1)
landscape interactions; (2)  direct effects of C02;  and (3)
biogenic emissions of radiatively important trace gases.  Scaling
issues to be resolved in this phase involve relating global scale
circulation patterns to regional scale weather and then to
landscape scale effects consistent with ecosystem processes.

     Experimental approaches will be initiated to improve the
conceptual models developed earlier and to permit more
quantitative modeling and understanding.  New research areas of
importance include (1)  remote sensing to detect areas of plant
stress, to inventory possible biogenic emission sources, and to
monitor ecological status; (2) ground-based inventories of
possible biogenic emissions sources; (3) quantification of
ecosystem-landscape processes and interactions; and (4) continued
hierarchical modeling of system and landscape level responses to
climate change.

     This phase will make possible a more quantitative assessment
of the potential ecological effects of climate change, including
identification of uncertainties and directions for research to
further reduce critical uncertainties.   The major change is that

                              18-17

-------
                                                   Research Needs

assessments at this time will have the choice of reflecting a
national scope with regional resolution or of focusing on
quantitative potential effects within one or a few sensitive
regions.

     The next stages of model enhancement should be to formulate
landscape-scale models.  This will involve linking models of
different resources and extending models from point or site
representations to include spatial variability.   Remote sensing
will play a key role in calibrating and validating such models.

     Simplifying modeling approaches to describe resource links
will be a major challenge.  One approach is "top-down" modeling,
similar to the approach first used to identify sensitive regions
(Landsberg, 1986).   Conceptual models will be constructed from
this perspective with process-based complexities added as needed.
While it will be necessary to account for additional variables at
individual sites, this may not be necessary for describing
regional patterns.

     Major emphases must be placed on linking models or model
results across ecosystem boundaries.  One approach will include
searching for response surfaces that can directly link inputs and
outputs, bypassing internal model complexities.   These response
surfaces could be used to represent model behavior in linked
systems.  The original, process-based models would be retained
for testing and evaluation purposes.  Linking models at both the
landscape and regional scales should then provide information on
the important processes and inputs at that scale, and as well as
on what climatic signals are transferred to other scales.

Regional Estimates and Trends Detection

     A long-term requirement for environmental effects research
is an inventory of ecosystems and landscape units on a regional
basis.  Statistical methods for trends detection over time and
space will also be needed.  The land management agencies, the
National Science Foundation, the Department of Energy, and EPA
all have existing and planned activities in these areas.
Resource inventories and ecological monitoring data must continue
to be high priorities for funding, if we ever hope to be able to
validate our current or planned models of ecosystem response to
climate changes.
ATMOSPHERIC SCIENCES RESEARCH

     The goal in the proposed strategy for atmospheric sciences
research is to better understand the physical and chemical
dynamics of the atmosphere to assess the impact of climate and

                              18-18

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Chapter 18
climate change on the environment.  Research is needed to produce
scenarios of both physical and chemical atmospheric conditions
that will support ecological assessments and policy analyses of
the effect of global climate change on regional environmental
resources (Kellogg and Schware, 1981; Wigley et al., 1986; NRC,
1982).  We will refer to these more comprehensive scenarios
simply as "climate scenarios," with reference to both the
physical and chemical components of the atmosphere as climate.

Objectives

     Four objectives must be achieved to accomplish the overall
goal:

     1.   To produce regional climate scenarios that address
          biological and ecological responses, incorporating
          appropriate meteorological and chemical dynamics that
          are related to the expected biological effects.

     2.   To produce regional climatic scenarios that allow
          assessments of future tropospheric and boundary layer
          air quality for regulatory and policy analysis.

     3.   To enhance understanding of the atmospheric phenomena
          controlling impacts by producing models that describe
          the physical and chemical processes and their
          interactions on subregional to global scales.

     4.   To examine secular air quality and climate changes to
          identify important current trends and to allow
          evaluation of model predictions and the testing of
          mechanistic hypotheses.

     Major research efforts are needed to link anthropogenic
changes in atmospheric chemistry, changes in climate, and the
effects of the new climate on environmental systems.  The
National Science Foundation, National Oceanic and Atmospheric
Administration, the National Aeronautics and Space
Administration, and the Department of Energy have traditionally
been the major contributors to research in these aspects of the
atmospheric sciences because of their support for development and
analysis of general circulation models (GCMs).  Their current and
planned research programs are vital to continued progress and
success in linking the atmospheric and ecological sciences.  EPA,
because of its existing expertise in meteorology and atmospheric
chemistry, and its emphasis on environmental effects, will become
an increasingly large contributor as well.
                              18-19

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                                                   Research Needs

Research Strategy

     Process models offer the potential for quantitative,
deterministic understanding but suffer from known (and perhaps
some unknown) deficiencies and limitations due to generalizing,
parameterizing, or distorting physical and chemical
relationships.  Such deficiencies are unavoidable, so models must
be tested for both sensitivity and accuracy.  The scale of the
model is chosen based upon the nature of the problems being
studied.  As a consequence, some processes are important factors
on one scale of space and time but not on another.  While the
level of confidence in individual models varies widely from one
use to another, it is clearly possible, as shown in this report,
to produce early versions of atmospheric scenarios.  These early
efforts are clearly not entirely satisfactory, but they have
provided useful directions for additional work.  The approach
from here on must be iterative in nature.  Because models will
not be able to provide all the needed information, analogue and
statistical techniques must also be used.

Scenario Production

     Scenario production in the future should be a three-step
process involving the following: defining the needs of the users
for scenarios; choosing, combining, and integrating the various
methods of producing scenarios; running the various process and
analogue models to produce sets of numbers, with guidance on
their use; and distributing the scenarios to the research
community.  This will be an iterative process, producing new
scenarios tailored to user needs and changing as models are
developed or refined.

     Because no one scenario will meet all the needs of
ecological research groups concerned with different effects, a
large number of scenarios tailored to the needs of each research
group will have to be produced.  For all the users, however,
scenarios must address the frequency of occurrence of weather
events; the significance of the environmental consequences; the
degree of understanding connecting weather events and their
consequences; and the knowledge of whether or not the proper
atmospheric information can be provided (Robinson and Hill,
1987) .

     Scenario production teams will require statements of data
needed from their clients.  One potential problem is that many
user needs for climatic data are poorly understood and defined,
due in part to a lack of interaction between climatologists and
other scientific disciplines.
                              18-20

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Chapter 18
     General circulation models, as have been used for this
report, are only partially suited for these purposes; regional
and continental-scale simulations of precipitation, cloudiness,
and soil moisture, and resolution of regional-climate detail on
coarse computational grids, are all problems that need to be
addressed.  GCMs also do not include many atmospheric processes,
such as chemistry and boundary layer meteorology.  Since much of
the necessary ecological research will be on the regional scale,
GCM output must be augmented for scenario development.  Promising
approaches include using large-scale two-dimentional chemical
models, regional air quality models, and analogue and statistical
techniques.  These various approaches need to be developed in a
manner that will allow their inputs and boundary conditions to be
taken, directly or indirectly, from GCMs.

     Once regional models, large-scale models, and analogue
techniques have been developed separately, they should be linked
where desirable to produce the optimal tools for scenario
production.  One example might be to use analogue methods to
modify the output of a GCM, then to use the output as input
boundary conditions for regional climate and air quality models,
then to use other methods to change their output from episodic to
long-term means, and finally to use weather generators to find
exceedances of air quality standards, drought probability, or
other climatic indicators of interest in a small region.

     The components mentioned above that make up atmospheric
scenarios each need development programs.  They are described in
subsequent sections.

General Circulation Models

     The major strength of general circulation models is that
they are strictly process-oriented, and are thus capable of
indicating the nature, magnitude, and causes of climate change.
Not all processes can be treated in full detail; many must be
incorporated through parameterization schemes that relate, either
statistically or empirically, the processes to the output
variable of concern.  The major weakness of general circulation
models is that their prediction capabilities are well
characterized primarily for temperature and precipitation, which
may not be sufficient variables for particular assessments.
Furthermore,  GCMs have difficulty predicting changes in regional
climate.  Therefore, techniques are needed to translate the
significant portions of large-scale climate change available from
these models into the smaller scales on which ecosystem effects
usually take place.   This spatial and temporal detail can be
                              18-21

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                                                   Research Needs

provided using either local models or historical analogue
approaches.

Local Climate Models

     Numerous process-oriented models have been developed on the
scale of individual point-sources.  While the basic model
formulations are site-independent, the results depend on local
conditions, and extrapolation is therefore difficult or
impossible.  Similarly, air quality models have characterized the
urban boundary layer and considered detailed processes, but it is
presently extremely difficult to produce a detailed model
applicable to anything other than the specific location for which
the parameterization was developed.

     Mesoscale models are being developed,, however, and the
process orientation of mesoscale meteorological models suggests
that they have the potential to be incorporated explicitly as
subgrid scale processes within GCMs.  One of the best developed
of these models is MM-4, a numerical model designed to simulate
or predict atmospheric circulation systems for short time periods
on a spatial scale ranging from 20 to 2,000 km.  MM-4 has been
used to drive the Regional Acid Deposition Model (RADM) and can
itself be driven by large-scale GCMs.  It is not, however, a
climate model and cannot presently be used as such.

     One area where major improvements of local climate models
can be expected is cloud processes.  Clouds are strong players in
potential nonlinear climate feedbacks, particularly on a
subregional scale, as they influence radiative transfer, chemical
reactions, transport of pollutants, and precipitation.  Current
models assume clouds exist when certain saturation or near-
saturation conditions are met; however, real clouds form when
supersaturation conditions exist relative to cloud condensation
nuclei.  There is a strong potential for feedback through changes
in the ultraviolet part of solar radiation that affects the
formation of cloud condensation nuclei.  Before any local climate
models can be built, linkages between atmospheric chemistry,
cloud condensation nuclei, and the formation of all types of
clouds must be understood.

Chemical Models

     EPA is one of the national leaders in the construction,
testing, and operation of regional-scale, three-dimensional
meteorological and chemical transformation process models.  These
models have improved the understanding of the complex and
nonlinear interactions of regional emissions, long-range
transport, and free-radical gas phase and cloud (aqueous) phase
chemistry of trace gases and aerosols.  A natural extension of

                              18-22

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Chapter 18
the present EPA mission is to expand these process-based tools to
incorporate elements needed to address the effects of global
climate change on the atmospheric environment.

     Scale differences, both temporal and spatial, are a major
impediment to simply merging modeling techniques between the
climate model and regional air quality communities.  Likewise,
simply adding chemistry to a GCM is not presently feasible for
the following reasons: (1) even the simplest chemistry model is
presently very computer-intensive; and (2) due to the large
spatial scales in GCMs, much of the critical
concentration-dependent chemistry of the urban and industrial
sources would be lost as the emissions were "smeared" over the
whole grid cell volume.  The manner in which emissions or sources
affect global climate change must be understood through an
understanding of how many of the trace gases are changed by urban
and regional chemical systems.  At the same time, changes in
global climate will modify how the urban and regional chemistry
and climate systems behave.  Improvements in basic computer
science and technology may help solve some of the strictly
computational problems.  However, the other issues require new
science.

     More developmental work is needed to improve our
understanding of chemical mechanisms, especially for aromatic and
biogenic species, before these mechanisms can reliably predict
the fate of much of the mass of material emitted into the
atmosphere by human sources.

Linking Available Models

     Chemical and climate models have been developed largely in
isolation from each other, so the process of linking them is not
simple.  In addition to technical problems associated with
computer limitations, model structures,  and basic formulation, a
major problem area exists: merging the differing temporal and
spatial scales used.

     From the perspective of regional chemical modeling, the
major research question must be: "How are the existing regional
models, which are all episodic (a few days at most) in design and
operation, and which need boundary conditions and externally
specified weather streams, to be used to estimate the impacts of
global climate change?"  Clearly, we will need to incorporate new
data sources, perhaps especially remote sensing of vegetation
types, atmospheric chemical composition (Whitten, 1986), and
climate into our modeling systems.
                              18-23

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                                                   Research Needs

Model Evaluation

     Performing model evaluations for models as complex as those
discussed here requires a concerted group effort involving many
scientists with both observational and theoretical skills and
experience.  A range of models will often be needed to understand
these complex systems.  To test such models, data will be needed
that are associated with the operational aspects of the models
(their ability to predict the items of interest) and the
diagnosis of model performance (their ability to give the right
answer for the right reason).  Several problems exist in model
evaluation, including observations taken at a different scale
from the model's predictions; no available technology that can
measure what the model calculates; model outputs that must be
inferred from secondary data; models with incomplete descriptions
of processes; biases of groups developing models; and different
assumptions and scenarios used by different modeling groups.
Accounting for these limitations will require field observations,
laboratory data, or the use of simpler models emphasizing the
processes being investigated.

Observational Analysis

     Analyses are needed that provide information about the
current state of the climate with emphasis on secular trends and
their regional variations.  These are needed for (1) the
evaluation of process models, and (2) the production of scenarios
for ecological and air quality risk assessments.  There are many
variables and time and space scales of interest.  Two general
needs, then, are to (1) develop methods of analysis capable of
spanning several scales and variables, and (2)  to develop
priorities for particular variables and scales for specific
purposes.

     In general, the traditional physical elements of climate
have been measured at numerous sites for many years.  Other
elements may have long records at a fairly restricted number of
sites.  In addition, a long tradition of paleoclimatic research
using proxy data has provided a very long record for some regions
and variables.

     In contrast, the chemical variables of climate are routinely
measured at few sites, and even those tend to have short record
lengths.  Few paleoclimatic investigations have considered
chemical variables; however, some chemical data are becoming
available from tree ring and ice core elemental analysis.

     Quality control of observations of physical climate
variables must be a major concern prior to any detailed
climatological analysis.  Many observations were originally

                              18-24

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Chapter 18
obtained for operational weather forecasting purposes, so quality
control was a relatively minor concern.  There may have been
changes in observational practices and equipment or in the
surrounding area that may have created spurious climate changes.
Adjusting climatic data sets is a difficult and highly skilled
task; however, several data sets are available or are being
developed (Karl et al., 1987).

     The majority of quality-controlled data sets being developed
emphasize factors needed for comparison with GCMs.  However, for
a particular scenario, these may not be the appropriate variables
or time period.  Quality controlled information on other
variables, such as humidity or extreme winds, may be required.
Another troublesome potential stems from the general failure to
rigorously address the question of quality control of satellite-
derived information.

Current Climate Statistics

     The development of current climate statistics must be based
on analytical techniques capable of addressing various time and
space scales for different variables, requiring the use of
appropriate statistical techniques combined with physical and
chemical insight.  The selection of appropriate summarizing
statistics is complicated when the record is a continuously
varying function on several time scales.  Choosing stations
representative of regions and scaling up from a series of points
to a value representative of an entire area introduces further
problems.

     These questions have been addressed in the most depth on the
global scale; however, apart from temperature, no physical
climate variable has been assessed on a global scale (Mitchell,
1984; Jones et al., 1986).  Chemical variables that have been
assessed globally include gases such as CO2  and  CH4.  Regional
variations,  such as for tropospheric ozone concentrations, have
also received considerable attention.  Subglobal physical
analyses have emphasized the continental scale.   The regional
scale has also been the one at which many of the long-term data
sets have been developed (e.g., Karl et al., 1984; Lamb,  1987).

     These analyses provide a wealth of detail about the current
climate and its recent variability.  However, identifiable
deficiencies in the present state of knowledge remain,  including
the following:  (1) no common statistical rationale to allow
comparisons, and (2) an emphasis on surface phenomena without
linkage to causal atmospheric phenomena, thus making linkage with
process models or use in scenario development difficult.

                              18-25

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                                                   Research Needs
     A high priority is the development of a statistical
framework for future analyses.  The framework will need to allow
flexibility when considering different variables in different
regions, while allowing comparisons between analyses and
providing a straightforward means of comparing results with
process models.

     Chemical elements of climate must also be studied to develop
appropriate statistical methods of spatial and temporal analyses,
development of techniques to link the various scales of interest,
and development of techniques to relate the near-surface climate
to the overall atmospheric processes causing them.  A severe
handicap for current work stems from the relative sparseness of
the data.

Analogue Scenarios

     Analogue scenarios are of two major types: those based on
paleoclimatic data from proxy evidence (e.g., tree rings or lake
sediments),  and those based on the modern historical record.
They have been developed primarily as complements to GCM results,
to contribute to the understanding of how altered processes are
reflected in different climates (Butzer,  1980; Williams and
Wigley, 1983).  Because of their connection to process models,
currently available scenarios have emphasized the variables given
by the models, mainly precipitation and temperature.  As before,
these may not be what the user of a scenario needs (Gates, 1985).
A potential exists, however, for the development of very detailed
analogue scenarios with specific user orientations.

     A major research challenge is the development of new,
scientifically valid techniques of analogue scenario production,
the creation or assembly of appropriate data sets, the assessment
of specific user needs, and the testing of the physical reality
of scenarios produced.  The analogue approach may provide the
detail of a scenario, while process models provide the boundary
conditions.   However, the analysis of current trends in regional
climate and the development of user-oriented analogue regional
scenarios are likely to indicate the need for additional
observational information.
RESEARCH INTEGRATION TOPICS

     This report has treated each regional case study as a
vehicle for illustrating potentially important environmental
effects that may result from a change in the climate system.
However, the capacity for truly integrating the research results
of individual projects within each region has been limited.  The

                              18-26

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Chapter 18
purpose of integrating diverse aspects of science in a regional
or subregional context is to ensure that scientific assessments
derived from a research program have an internally consistent set
of assumptions and relationships.  Future regional case studies
will need to address this problem, if regional and local concerns
of environmental decisionmakers are to be reflected in scientific
research and assessment.

Spatial Data Bases for Integration

     Research in both the ecological and atmospheric sciences
should produce early, qualitative estimates of continental and
regional sensitivities based on the current understanding of
environmental resources and the processes that control the
responses of each ecosystem to climatic variability.  The
beginning stages of this process have clearly been taken in this
report and will be added to, as noted earlier in this chapter.

     However, once the early definitions of sensitivity have been
made, there still remains the daunting task of determining the
possible relationships between climatic variability and the
underlying systems in the atmosphere and biosphere in a way that
will enable future regional studies to best investigate
sensitivities to climate change.  This can be done only if
current results and understandings are portrayed in a manner that
will take into account both the actual results from modeling and
experimental studies and their location on the landscape, i.e.,
in spatially structured data bases, analyzed with geographic
information system (CIS) technologies.

     Such spatially structured data bases can be used to produce
maps, but their use goes far beyond traditional two-dimensional
representations of geographic data.  In particular, their main
advantage may be the potential to track not only the results of
experiments but also the uncertainty associated with both
underlying measurements and with modeling algorithms.  Thus, the
spatially oriented data bases, if used in conjunction with
geographic information system technology, can play both an
assessment role and a quality assurance role.

     Spatially oriented data bases therefore have three major
purposes: (1) they provide a method of prioritizing research
efforts within funding constraints; (2) they provide a ready-made
method for validating projections, especially if temporal scales
can be portrayed adequately; and (3)  they provide a direct
relationship to the regional, national, and international policy
issues that are of most concern to environmental decisionmakers.
                              18-27

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                                                   Research Needs

     The production of such data bases should be thought of as
the first stage in an ongoing iterative procedure.  The initial
state of the science will both qualitatively, and in some cases
quantitatively, limit the utility of maps.   However, the research
priorities outlined here and pursued by other Federal and
international organizations should enable us to improve the
underlying information base and thereby improve the next
estimates of resources' responses to climate change.

Scenario-Assessment Approach to Integration

     Integrated modeling has been attempted in large-scale
environmental issues many times before and may be useful for
policy analysis or for heuristic purposes.   However, the goal of
a model adequate to simulate the dynamics of geophysical,
chemical, and biological processes on global scales is clearly
achievable only after decades of research (ESSC, 1988).

     Given that achieving such a goal is at least several decades
in the future, the question of integrating diverse aspects of
science in global climate change and its potential effects still
must be addressed now.  A promising approach for integrating
research results is to treat the entire cycle of information flow
(Figure 18-5a) as a series of two-stage or three-stage processes
(Figures 18-5b and 18-5c).

     Within each two-stage process, research results should be
treated as follows.  The first part of the process will be the
creation of a set of scenarios, where we define a scenario as a
possible and plausible combination of variables derived from a
set of internally consistent assumptions.  The second part of the
process will evaluate the range of changes that are potentially
due to each scenario and will evaluate the sensitivity of the
underlying systems to different aspects of the scenarios.  Thus,
scenarios of land-use change can be used to evaluate the possible
changes in emissions; scenarios of emissions can be used to
evaluate the possible changes in atmospheric composition;
scenarios of atmospheric composition can be used to evaluate
changes in climate; climatic scenarios can be used to evaluate
the possible changes in ecosystems; and scenarios of ecosystem
and land-use change can in turn be used to evaluate possible
changes in emissions.

     The use of a scenario-assessment approach as an integrating
tool has several advantages.  It will provide clear priorities
for research on the sensitivities of important environmental
processes in each scientific area.  It maintains an holistic view
of the problems of global change.  It preserves the information
on the uncertainty of model results and data, in both qualitative
and potentially quantitative fashion.  Each pair of

                              18-28

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                       EMISSIONS
         Scenario
                        GLOBAL

                      ATMOSPHERIC

                       CHEMISTRY
                                    Scenario
                                        Assessment
         Assessment
                      ATMOSPHERIC

                      DYNAMICS
See
        ario
                       REGIONAL

                     ATMOSPHERES
      \

   Assessment
              HUMAN
               &
            INDUSTRIAL
             EFFECTS
                                    Scenario
                                    Assessment
 ENV.

Ect)LOG.
EFFECTS
                                            Scenario
                        EMISSIONS
                                        Assessment
Figure 18-5a.  Scenario approach to integration.


Source:
                          18-29

-------
  Seer
ario
     \
  Assessment
                       EMISSIONS
                            I
                       GLOBAL
                     ATMOSPHERIC
                      CHEMISTRY
                     ATMOSPHERIC
                     DYNAMICS
                                              Scenario
                                              Assessment
Figure 18-5b.  Scenario approach to integration.
Source:
                          18-30

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                     ATMOSPHERIC
                      DYNAMICS
  Scenario
                          i
                         Scenario
                      REGIONAL
                     ATMOSPHERES
                         Assessment
  Assessment
  HUMAN
    &
INDUSTRIAL
 EFFECTS
                     t
 ENV.
   &
ECOLOG.
EFFECTS
                                            See
nario
                        EMISSIONS
                                I
                             Assessment
Figure 18-5c.  Scenario approach to integration.

Source:
                          18-31

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                                                   Research Needs

scenario-response steps is explicitly decoupled from other pairs,
while remaining consistent with them.  Thus, this approach can
indicate both ranges and sensitivities of responses in
potentially verifiable fashion within each pair, but does not
attempt the premature task of modeling uncertainty all the way
through the global system.

     The use of scenarios as assessment and integrative tools is
not a traditional scientific approach toward prediction and
validation.  Nevertheless, it is important from three
programmatic standpoints:

     1.   To be relevant to policymakers, a continued iterative
          process of evaluating the state of knowledge in the
          suite of sciences that are relevant to global climate
          change must be maintained.  An iterative process of
          using and analyzing scenario-based assessments can
          provide such information in a usable and informative
          way.

     2.   To achieve the multidisciplinary syntheses needed to
          make scientific advances in problems of global climate
          change, evaluation must continue of the methods by
          which predictions are made, by which scenarios of
          change can be composed, and of the sensitivities of
          affected processes.  The scenario-based assessment
          approach provides a ready-made integrating framework
          for such continual evaluation.

     3.   Because of the importance of this proposed research in
          public policy arenas, it is critical not to lose sight
          of what is and is not predictable.  By distinguishing
          between a set of scenarios and actual verifiable
          predictions, the scenario-based approach can best
          illustrate the difference without becoming a morass of
          hedged bets.
CONCLUSION

     In this chapter, we have attempted to lay out some of the
most important strategic areas for scientific research in
deriving an understanding of the environmental consequences of
global atmospheric change.  The recommendations have not been
limited to the ecological sciences but have addressed the
atmospheric sciences as well.  Throughout, the focus has been on
the research topics in the environmental sciences that will have
the best chance of producing information that will be of use to
environmental decisionmakers and policymakers.
                              18-32

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Chapter 18
     In so doing, we have made suggestions that transcend
research efforts that the Environmental Protection Agency will be
able to pursue on its own.  Our intent in doing so is to
underscore the institutional requirements for cooperation among
U.S. and international research organizations; close coordination
with efforts such as the International Geosphere Biosphere
Programme (NAS, 1986) ; and a continuing need for productive
dialog between scientists and policy analysts.  Our hope is that
this report, and the research needs outlined here, can be seen as
a beginning step in this direction.
                              18-33

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                                                   Research Needs

       Table 18-1:  Major Research Topics From This Report
Research Area

Water Resources
Agriculture
Forest Ecosystems
Human Health



Air Quality


Fishery Resources
General Circulation
Models
Role of climate change

Analyses of impacts on small lakes and
 streams
Better estimates of rainfall, runoff
 relationships, and regional runoff
 patterns
Analyses of relationship between waterflow
 and water quality
Analyses of changes in pesticide and
 fertilizer management practices on water
 quality

Interactive effects of carbon dioxide,
 climate change, air pollution, and
 ultraviolet-B  (UV-B) radiation
Development of drought-resistant varieties
Field studies to validate crop yield models

Processes and rates of migration in
 critical regions
Changes in land-use practices
Interactive effects of climate change, air
 pollution, UV-B radiation, and carbon
 dioxide
Ecosystem-level processes quantified for
 different landscape types
Modeling and sampling strategies for
 regional effects

Methods for assessing morbidity, mortality
 patterns
Influence on disease vectors

Influence on urban, mesoscale air quality
 including acid deposition and zones

Impacts in sensitive estuaries
Shifts of distributions in near-coastal
 species
Ecological impact on freshwater species

Climate variability for lxC02 and  2xCO2
Simulations of climate on regional and
 local scales
Simulations of major storms, hurricanes,
 and blocking events
                              18-34

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Chapter 18
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Chapter 18
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                                                   Research Needs
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                        AUTHORS
Joseph J. Bufalini
Lauretta M. Burke

Margaret M. Daniel

Robert L. DeVelice


Eugene C. Durman


Peter L. Finkelstein
Anthony Janetos


Roy Jenne


Ross A. Kiester


George A. King


Kenneth P. Linder

Janice A. Longstreth

Linda 0. Mearns


Ted R. Miller

Mark W. Mugler

Ronald P. Neilson


Cynthia Rosenzweig
USEPA - Atmospheric Research
and Exposure Assessment
Laboratory - Research Triangle
Park, North Carolina

The Bruce Company

The Bruce Company

USEPA - Environmental Research
Laboratory - Corvallis, Oregon

USEPA Office of Policy,
Planning and Evaluation

USEPA - Atmospheric Research
and Exposure Assessment
Laboratory - Research Triangle
Park, North Carolina

USEPA - Office of Research and
Development

National Center for
Atmospheric Research

USEPA - Environmental Research
Laboratory - Corvallis, Oregon

USEPA - Environmental Research
Laboratory - Corvallis, Oregon

ICF, Inc.

ICF, Inc.

National Center for
Atmospheric Research

The Urban Institute

Apogee Research,  Inc.

USEPA - Environmental Research
Laboratory - Corvallis, Oregon

Columbia University/Goddard
Institute for Space Studies
                          A-l

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William E. Riebsame

Michael C. Rubino

Joel B. Smith


Dennis A. Tirpak


James G. Titus


Jack K. Winjurn


Robert C. Worrest
University of Colorado

Apogee Research, Inc.

USEPA Office of Policy,
Planning and Evaluation

USEPA Office of Policy,
Planning and Evaluation

USEPA Office of Policy,
Planning and Evaluation

USEPA - Environmental Research
Laboratory - Corvallis, Oregon

USEPA - Environmental Research
Laboratory - Corvallis, Oregon
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             CONTRIBUTING INVESTIGATORS AND PROJECTS
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Adams,  Richard M.,  J.  David Glyer,  and Bruce A.
McCarl
Oregon State University
The  Economic  Effects  of  Climate  Change  on U.S.
Agriculture:  A Preliminary Assessment.

Allen, Richard C., and Francis N. Gichuki
Utah State University
Effects of Projected C02-Induced  Climate  Changes on
Irrigation Water  Requirements  in the Great Plains
States.

Assel, Raymond, A.
Great Lakes Environment Research Lab
Impact of Global Warming on Great Lakes Ice Cycles.

Baldwin, Malcolm F.
Baldwin Associates
Applicability  of  Federal  Long-Range  Planning and
Environmental Impact Statement Processes to Global
Climate Change Issues.

Blumberg, Alan F., and Dominic M. DiToro
HydroQual, Inc.
The Effects of  Climate  Warming on Lake Erie Water
Quality.

Botkin,  Daniel  B.,  Robert A.  Nisbet, and  Tad E.
Reynales
University of California, Santa Barbara
Effects of Climate Change  on Forests of the Great
Lakes States.

Byron, Earl R. , Alan Jassby,  and  Charles R. Goldman
University of California, Davis
The Effects of  Global Climate  Change on the Water
Quality of Mountain Lakes and Streams.

Changnon,  Stanley A. ,  Steven  Leffler,  and  Robin
Shealy
University of Illinois
Impacts of Extremes in  Lake  Michigan Levels along
Illinois Shorelines:   Low Levels.
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Croley, Thomas F., and Holly C. Hartmann
Great Lakes Environment Research Lab
Effects of Climate Changes on the Laurentian Great
Lakes Levels.

Davis, Owen K.
University of Arizona
Ancient Analogs  for  Greenhouse Warming of Central
California.
Dudek, J. Daniel
Environmental Defense Fund
Climate   Change   Impacts  upon   Agriculture
Resources:  A Case Study of California.
    and
Easterling, William E.
University of Illinois
Farm-Level Adjustments by  Illinois Corn Producers
to Climate change.
Glantz, Michael
National Center for Atmospheric Research
Societal  Responses  to Regional  Climate
Forecasting by Analog.
Change:
Haile, Daniel G.
U.S. Department of Agriculture, Agriculture Research
Service - Gainesville
Computer Simulation  of  the Effects  of  Changes in
Weather    Pattern    on    Vector-Borne    Disease
Transmission.

Hains, David K.
C.F. Hydrologist, Inc.
Impacts on Runoff in the Upper Chattahoochee River
Basin.

Johnson, Howard L.,  Ellen J. Cooter, arid Robert J.
Sladewski
University of Oklahoma
Impacts  of   Climate  Change   on  the   Fate  of
Agricultural  Chemicals   Across  the  U., S.A.  Great
Plains and Central Prairie.
          I
Josselyn, Michael, and John Callaway
San Francisco State University
Ecological  Effects   of   Global   Climate
Wetland Resources of San Francisco Bay.
Change:
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Kalkstein, Laurence S.
University of Delaware
The  Impact of  CO2  and Trace  Gas-Induced Climate
Changes upon Human Mortality.

Keith, Virgil  F.,  Carlos DeAvila,  and Richard M.
Willis
Engineering Computer Optecnomics, Inc.
Effect of  Climatic  Change  on Shipping within Lake
Superior and Lake Erie.

Leatherman, Stephen P.
University of Maryland
National   Assessment   of    Beach   Nourishment
Requirements Associated with Accelerated Sea Level
Rise.

Lettenmaier,  Dennis P., Thian Yew Gan,  and David R.
Dawdy
University of Washington
Interpretation  of  Hydrologic  Effects  of  Climate
Change in  the  Sacramento-San Joaquin River Basin,
California.

Linder, Kenneth P., and Mark R. Inglis
ICF, Inc.
The Potential Impacts of Climate  Change on Electric
Utilities:  Regional and National Estimates.

Livingston, Robert J.
Florida State University
Projected Changes in Estuarine Conditions Based on
Models of Long-Term Atmospheric Alteration.

Longstreth, Janice, and Joseph Wiseman
ICF, Inc.
The Potential Impact of Climate Change on Patterns
of Infectious Disease in the United States.

Magnuson, JohnJ., Henry A.  Regier, Brian J. Shuter,
David K.  Hill, John A. Holmes, and J. Donald Meisner
University of Wisconsin
Potential Responses of Great  Lakes Fishes and their
Habitat to Global Climate Warming.
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Title:
McCormick, Michael J.
Great Lakes Environment Research Lab
Potential  Climatic  Changes  to  the  Lake Michigan
Thermal Structure.

Mearns, Linda O.
National Center for Atmospheric Research
Analysis of Climate Variability in GCM Control Runs.

Meo, Mark, and Steve Ballard
University of Oklahoma
Policy  Implications  of  Global  Climatic  Change
Impacts   upon   the  Tennessee   Valley  Authority
Reservoir System, Apalachicola River, Estuary, and
Bay, and South Florida.
Miller, Barbara, and W. Gary Brock
Tennessee Valley Authority
Potential  Impacts  of   Climatic   Change  on
Tennessee Valley Authority Reservoir System.
the
Morris, Ralph E., Michael W. Gery, Mei Kao Liu, Gary
E. Moore, Chris Daly, and Stanley M. Greenfield
Systems Applications, Inc.
Examination of the Sensitivity of a Regional Oxidant
Model to Climate Variations.

Overpeck, Jonathan T.,  and Patrick J. Bartlein
Lamont-Doherty Geological Observatory
Assessing  the Responses  of Vegetation  to  Future
Climate Change:  Ecological Response Surfaces and
Paleological Model Validation.

Park, Richard A., Manjit S.  Trehan, Paul W. Mausel,
and Robert C. Howe
Butler University
The  Effects  of  Sea Level  Rise  on  U.S.  Coastal
Wetlands.

Peart, Robert M., James W. Jones, and R. Bruce Curry
University of Florida
Impact  of  Climate  Change  on  Crop  Yield  in  the
Southeastern U.S.A.

Penner,  Joyce E.,  Peter  S.  Connell,   Donald  J.
Wuebbles, and Curtis C.  Covey
Lawrence Livermore National Laboratory
Climate  Change  and  Its  Interactions  with  Air
Chemistry: Perspectives and Research Needs.
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Ray,  Daniel  K.,  Kurt N.  Lindland,  and William J.
Brah
The Center for the Great  Lakes
Effects of Global Warming on the Great Lakes:  The
Implications for Policies and Institutions.

Riebsame, William E.
University of Colorado
Some  Policy  Implications of Climate Change, with
Emphasis  on  Natural Resources  Management and the
Role  of Climate Perception on Policy Response.

Riebsame, William E., and Jeffrey W. Jacobs
University of Colorado
Some  Policy  Implications  of  Climate Change in the
Sacramento-San Joaquin Region of California.

Rind, David
Goddard Institute for Space Studies
Change in Climate Variability in the 21st Century.

Ritchie, Joe T., Brian D. Baer, and T.Y. Chou
Michigan State University
Effect  of Global  Climate Change  on Agriculture:
Great Lakes Region.

Rose, Elise
Consultant
Direct Effects of Increasing C02 on Plants  and Their
Interactions with Direct  Climatic Effects.

Rosenzweig, Cynthia
Columbia University/Goddard Institute for Space
Studies
Potential Effects of Climate Change on Agricultural
Production in the Great Plains:   A Simulation Study.

Schmidtmann,  Edward T., and J.A. Miller
U.S. Department of Agriculture, Agriculture Research
Service - Beltsville, Maryland
Effect of Climate Warming  on Population of the Horn
Fly.

Schuh, G. Edward
University of Minnesota
Agricultural Policies  for Climate  Changes Induced
by Greenhouse Gases.
                               B-5

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Sheer, Daniel P., and Dean Randall
Water Resources Management Inc.
Methods  for  Evaluating  the  Potential  Impacts of
Global Climate  Change:  Case Studies  of the Water
Supply  Systems  of  the  State  of California  and
Atlanta, Georgia.

Stem, Edgar, Gregory A.  Mertz,  J. Dirck Strycker,
and Monica Huppi
Tufts University
Changing Animal  Disease  Patterns Induced  by  the
Greenhouse Effect.

Stinner, Benjamin R.,  Robin A.J. Taylor, Ronald B.
Hammond, Foster F. Purrington, David. A. McCartney,
Nick Rodenhouse, and Gary Barrett
Ohio State University
Potential Effects of Climatic Change on Plant-Pest
Interactions.

Titus, James G., and Michael Greene
U.S. Environmental Protection Agency
An Overview of the Nationwide Impacts of Sea Level
Rise.
Urban, Dean L.,  and Herman H. Sheer
University of Virginia
Forest Response  to Climate Change:
Study for Southeastern Forests.
A Simulation
Walker, Christopher  J.,  Ted R. Miller,  G.  Thomas
Kingsley,  and William A.  Hyman
The Urban Institute
Impact  of  Global   Climate   Change   on   Urban
Infrastructure.

Weggel,  J.  Richard,  Scott  Brown,  Juan  Carlos
Escajadillo, Patrick Breen, and Edward L. Doheny
Drexel University
The Cost  of Defending Developed  Shorelines Along
Sheltered Waters  of  the  United States  from a Two
Meter Rise in Mean Sea Level.

Williams,  Philip B.
Philip Williams & Associates
The Impacts of Climate Change on the Salinity of San
Francisco Bay.
                                                                     I
                               B-6

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Authors:       Woodman, James N., and Cari L. Sasser
Institution:   North Carolina State University
Title:         Potential Effects of Climate Change on U.S. Forests:
               Case Studies of California and the Southeast.

Author:        Yohe, Gary W.
Institution:   Wesleyan University
Title:         The Cost of Holding Back the Sea: Phase 1, Economic
               Vulnerability.

Author:        Zabinski, Katherine and Margaret Davis
Institution:   University of Minnesota
Title:         Hard Times Ahead  for  Great  Lakes Forests:   A
               Climate Threshold Model Predicts Responses to
               C02-Induced Climate Change.
                               B-7

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