-------
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
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Chapter 14
2 600
N,
(fl
500 -
> 400 -
300
200(4
100
A
HUMIDITY -,
I"
T /
RAINFALL
\
\
\
. \
\
f.x.
V\
i •
i
i-
t:
V\
\'J
JUNE
1967
JUNE
68
DEC'
JAN
I
JUNE
69
oe.
JAN
70
700-1-88
600—86
500—84
400--i
-82
-80
•78
IOO-f-76
300-
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
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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.
15-1
-------
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).
15-3
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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.
15-5
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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
15-7
-------
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.
15-9
-------
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.
15-15
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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
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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.
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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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16-13
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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
-------
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
-------
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
-------
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
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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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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
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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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17-35
-------
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.
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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.
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Chapter 17
REFERENCES
American Meteorological Society. 1985. Flash floods: a
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.
Institute of Meteorology and Hydrology, Bucharest, Romania, pp.
10-31.
Bates, G.T., and G.A. Meehl. 1986. The Effect of CO2
concentration on the frequency of blocking in a general
circulation model coupled to a simple mixed layer ocean model.
Monthly Weather Review 114:687-701.
Becker, R.J., and R.A. Wood. 1986. Heatwave. Weatherwise
39(4):195-6.
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
modeling of atmospheric flow by spectral methods. Methods in
Computational Physics 17:267-324.
Bridger, C.A., F.P. Ellis, and H.L. Taylor. 1976. Mortality in
St. Louis, Missouri, during heat waves in 1936, 1953, 1954, 1955,
and 1966. Environmental Research 12:38-48.
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
Press.
Coleman, J.E. 1988. Climatic warming and increased summer
aridity in Florida, U.S.A. Climatic Change 12:164-178.
17-41
-------
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.
17-42
-------
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
-------
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.
17-44
-------
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.
3-19.
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-
layer ocean model. Journal of Geophysical Research 89(D6):9475-
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;
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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
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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
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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.
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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.
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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
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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.
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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
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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
-------
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.
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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.
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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
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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
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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.
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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
REFERENCES
Ballou, S.W., Levenson, J.B., Robek, K.E., and Gabriel, M.H.
1981. Regional Ecological Assessments; Concepts, Procedures, and
Application. Argonne, IL: Argonne National Laboratory.
Barnthouse, L.W., DeAngelis, D.L., Gardner, R.H., O'Neill, R.V.,
Powers, C.D., Suter, G.W., and Vaughn, D.S. 1982. Methodology
for Environmental Risk Analysis. Oak Ridge, TN: Oak Ridge
National Laboratory, Environmental Science Division. Publication
No. 2679.
Bolin, B., Doos, B.R., Jager, J., and Warrick, R.A. 1986. The
Greenhouse Effect, Climate Change, and Ecosystems: SCOPE 29.
New York: John Wiley and Sons.
Borchert, J.R. 1959. The climate of the Central American
grassland. Annals AAG. 15(1).
Braun, E.L. 1950. Deciduous Forests of Eastern North America.
New York: Hafner Press.
Brown, D.E., and Lowe, C.H. 1980. Biotic Communities of the
Southwest. USDA Forest Service General Technical Report RM-78.
Bryson, R.A. 1966. Air masses, streamlines, and the boreal
forest. Geographical Bulletin. 8(3).
Butzer, K. 1980. Adaption to global environmental change.
Prof. Geogr.
Carbon Dioxide Assessment Committee. 1983. Changing Climate.
Washington, DC: National Academy Press.
Fowells, H.A. 1965. Silvics of Forest Trees of the United
States. Agriculture Handbook, No. 271. Washington, DC: USDA
Forest Service.
Gates, W.L. 1985. The use of general circulation models in the
analysis of ecosystem impacts of climate change. Climate change.
Hansen, J., Russell, G., Rink, D., Stone, P., Lacis, A., and
Lebedeff, S. 1983. Efficient three-dimensional global models
for climate studies: models I and II. Monthly Weather Review.
18-35
-------
Research Needs
Harwell, M.A., and Harwell, J.S. 1988. Environmental decision-
making in the presence of uncertainties. In: Levin, Harwell,
Kelly, and Kimball, eds. Ecotoxicology: Problems and Approaches.
New York: Springer-Verlag.
Karl, T.R., and Riebsame, W.E. 1984. The identification of 10-
and 20-year temperature and precipitation fluctuations in the
contiguous United States. Journal of Climatology and Applied
Meteorology.
Kellogg, W.W., and Schware, R. 1981. Climate Change and
Society: Consequences of Increasing Atompheric Carbon Dioxide.
Boulder, CO: Westview Press.
Lamb, P.J. 1987. On the development of regional climatic
scenarios for policy-oriented climatic-impact assessment.
Bulletin of the American Meteorologic Society.
Landsberg, J.J. University of Sussex. 1986. In: Sutcliff,
J.F., ed. Physiological Ecology of Forest Production from
Applied Botany: A Series of Monographs. London, England:
Academic Press.
MacCracken, M.C., and Luther, F.M. 1985. Projecting the
Climatic Effects of Increasing Carbon Dioxide. Washington, DC:
U.S. Department of Energy. DOE/ER-0237.
Mitchell, J.M. Jr. 1984. The effects of pollutants on global
climate. Meterological Magazine.
Mitchell, V.L. 1969. The Regionalization of Climate in Montane
Areas. Ann Arbor, MI: University Microfilms, Inc.
NAS. 1982. National Academy of Sciences. Carbon Dioxide and
Climate: A Second Assessment. National Academy of Sciences,
Climate Board.
National Academy of Sciences. 1986. Global Change in the
Geosphere-Biosphere: Initial Priorities for an IGBP. National
Research Council. Washington, DC: National Academy Press.
Neilson, R.P. 1986. High-resolution climatic analysis and
Southwest biogeography. Science 232.
North, W., and Yosie, T.F. 1987. Risk Assessment: What It Is;
How It Works. EPA Journal, U.S. Environmental Protection Agency,
13(9).
18-36
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Chapter 18
Robinson, P.J., and Hill, H.L. 1987. Toward a Policy for
Climate Impacts. Bulletin of the American Meteorological
Society.
Shands, W.E., and Hoffman, J.S. 1987. The Greenhouse Effect,
Climate Change, and U.S. Forests. Washington, DC: The
Conservation Foundation.
Solomon, A.M., and West, D.C. 1985. Potential Responses of
Forests to C02-Induced Climate Change. 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.
Trabalka, J.R., ed. 1985. Atmospheric Carbon Dioxide and the
Global Carbon Cycle. Washington, DC: U.S. Department of Energy.
DOE/ER-0239.
USGS. 1986. U.S. Geological Survey. National Water Summary
1985-Hydrologic Events and Surface-Water Resources. Washington,
DC: U.S. Government Printing Office.
Vankat, J.L. 1979. The Natural Vegetation of North America.
New York: John Wiley and Sons.
Wells, P.V. 1979. An equable glaciopluvial in the West:
pleniglacial evidence of increased precipitation on a gradient
from the Great Basin to the Sonoran and Chihuahuan Deserts.
Quaternary Research 12.
Wendland, W.M., and Bryson, R.A. 1981. Northern hemisphere
airstream regions. Monthly Weather Review 109.
White, M.R., ed. 1985. 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.
Whittier, T.R., Hughes, R.M., and Larsen, D.P. 1988. The
correspondence between ecoregions and spatial patterns in stream
ecosystems in Oregon. Canadian Journal of Fisheries and Aquatic
Sciences. In press.
Wigley, T.M.L., Jones, P.O., and Kelly, P.M. 1986. Empirical
climate studies: warm world scenarios and the detection of a
C02-induced climate change. In: Bolin, B., Doos, B.R., Jager,
J., and Warrick, R.A., eds. The Greenhouse Effect, Climate Change
and Ecosystems: SCOPE 29. New York: John Wiley and Sons.
18-37
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Research Needs
Williams, L.D., and Wigley, T.M.L. 1983. A Comparison of
Evidence for late Holocene summer temperature variations in the
northern hemisphere. Quaternary Research.
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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
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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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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.
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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.
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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.
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