United States
                           Environmental Protection
                           Agency
                            Office of Policy
                            (2111)
                           EPA 236-F-98-007bb
                           September  1998
       ©EPA       Climate   Change  And  Virginia
The earth's climate is predicted to change because human
activities are altering the chemical composition of the atmosphere
through the buildup of greenhouse gases — primarily carbon
dioxide, methane, nitrous oxide, and chlorofluorocarbons. The
heat-trapping property of these greenhouse gases is undisputed.
Although there is uncertainty about exactly how and when the
earth's climate will respond to enhanced concentrations of
greenhouse gases, observations indicate that detectable changes
are underway. There most likely will be increases in temperature
and changes in precipitation, soil moisture, and sea level, which
could have adverse effects on many ecological systems, as well
as on human health and the economy.
The Climate System

Energy from the sun drives the earth's weather and climate.
Atmospheric greenhouse gases (water vapor, carbon dioxide,
and other gases) trap some of the energy from the sun, creating
a natural "greenhouse effect." Without this effect, temperatures
would be much lower than they are now, and life as known today
would not be possible. Instead, thanks to  greenhouse gases, the
earth's average temperature is a more hospitable 60°F. However,
problems arise when the greenhouse effect is enhanced by
human-generated emissions of greenhouse gases.

Global warming would do more than add a few degrees to today's
average temperatures. Cold spells still would occur in winter, but
heat waves would be more common. Some places would be drier,
others wetter. Perhaps more important, more precipitation may
come in short, intense bursts (e.g., more than 2 inches of rain
in a day), which could lead to more flooding. Sea levels would
be higher than they would have been without global warming,
although the actual changes may vary from place to place
because coastal lands are themselves sinking or rising.

               The Greenhouse Effect
               Some solar radiation
                is reflected by the
                 earth and the
                 atmosphere
Some of the infrared radiation passes
through the atmosphere, and some is
absorbed and re-emitted in all directions
by greenhouse gas molecules. The effect
of this is to warm the earth's surface and
the lower atmosphere.
     Source: U.S. Department of State (1992)
                               Emissions Of Greenhouse Gases

                               Since the beginning of the industrial revolution, human activities
                               have been adding measurably to natural background levels of
                               greenhouse gases. The burning of fossil fuels — coal, oil, and
                               natural gas — for energy is the primary source of emissions.
                               Energy burned to run cars and trucks, heat homes and busi-
                               nesses, and power factories is responsible for about 80% of
                               global carbon dioxide emissions, about 25% of U. S. methane
                               emissions, and about 20% of global nitrous oxide emissions.
                               Increased agriculture and deforestation, landfills, and industrial
                               production and mining also contribute a significant share of
                               emissions. In 1994, the United States emitted about one-fifth of
                               total global greenhouse gases.
                               Concentrations Of Greenhouse Gases

                               Since the pre-industrial era, atmospheric concentrations of carbon
                               dioxide have increased nearly 30%, methane concentrations have
                               more than doubled, and nitrous oxide concentrations have risen
                               by about 15%. These increases have enhanced the heat-trapping
                               capability of the earth's atmosphere. Sulfate aerosols, a common
                               air pollutant, cool the atmosphere by reflecting incoming solar
                               radiation. However, sulfates are short-lived and vary regionally,
                               so they do not offset greenhouse gas warming.

                               Although many  greenhouse gases already are present in the
                               atmosphere, oceans, and vegetation, their concentrations in the
                               future will depend in part on present and future emissions.
                               Estimating future emissions is difficult, because they will depend
                               on demographic, economic, technological, policy, and institu-
                               tional developments. Several emissions scenarios have been
                               developed based on differing projections of these underlying
                               factors. Forexample, by 2100, in the absence of emissions control
                               policies, carbon dioxide concentrations are projected to be 30-
                               150% higher than today's levels.
Current Climatic Changes

Global mean surface temperatures have increased 0.6-1.2°F
between 1890 and 1996. The 9 warmestyears in this century all
have occurred in the last 14 years. Of these, 1995 was the warmest
year on record, suggesting the atmosphere has rebounded from
the temporary cooling caused by the eruption of Mt. Pinatubo in
the Philippines.

Several pieces of additional evidence consistent with warming,
such as a decrease in Northern Hemisphere snow cover, a
decrease in Arctic Sea ice, and continued melting of alpine
glaciers, have been corroborated. Globally, sea levels have risen

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     Global Temperature Changes (1861-1996)
                               Year
    Source: IPCC (1995), updated

4-10 inches over the past century, and precipitation over land has
increased slightly. The frequency of extreme rainfall events also
has increased throughout much of the United States.

A new international scientific assessment by the Intergovern-
mental Panel on Climate Change recently concluded that "the
balance of evidence suggests a discernible human influence
on global climate."


Future Climatic Changes

For a given concentration of greenhouse gases, the resulting
increase in the atmosphere's heat-trapping ability can be pre-
dicted with precision, but the resulting impact on climate is more
uncertain. The climate system is complex and dynamic, with
constant interaction between the atmosphere, land, ice, and
oceans. Further, humans have never experienced such a rapid rise
in greenhouse gases. In effect, a large and uncontrolled planet-
wide experiment is being conducted.

General circulation models are complex computer simulations that
describe the circulation of air and ocean currents and how energy
is transported within the climate system. While uncertainties
remain, these  models are a powerful tool for studying climate. As
a result of continuous model improvements over the last few
decades, scientists are reasonably confident about the link
between global greenhouse gas concentrations and temperature
and about the  ability of models to characterize future climate at
continental scales.

Recent model calculations suggest that the global surface temper-
ature could increase an average of 1.6-6.3°F by 2100, with signif-
icant regional variation. These temperature changes would be far
greater than recent natural fluctuations, and they would occur
significantly faster than any known changes in the last 10,000
years. The United States is projected to warm more than the
global average, especially as fewer sulfate aerosols are produced.

The models suggest that the rate of evaporation will increase as
the climate warms, which will increase average global precipita-
tion. They also suggest increased frequency of intense rainfall as
well as a marked decrease in soil moisture over some mid-
continental regions during the summer. Sea level is projected to
increase by 6-38 inches by 2100.

Calculations of regional climate change are much less reliable
than global ones, and it is unclear whether regional climate will
become more variable. The frequency and intensity of some
extreme weather of critical importance to ecological systems
(droughts, floods,  frosts, cloudiness, the frequency of hot or cold
spells, and the intensity of associated fire and pest outbreaks)
could increase.

Local Climate Changes

Over the last century, the average temperature near Richmond.
Virginia, has increased 0.2°F, and precipitation has increased by
up to  10% in many parts of the state. However, trends in other
parts of Virginia show decreases in temperature. The exact
reasons for these differences in trends are unknown. However.
there are regional differences in the concentrations of particulates
and aerosols in the atmosphere that affect the amount of heat
that is trapped or reflected. These past trends may or may not
continue into the future.

Over the next century, Virginia's climate may change even more.
For example, based on projections made by the Intergovernmental
Panel on Climate Change and results from the United Kingdom
Hadley Centre climate model (HadCM2), a model that accounts
for both greenhouse  gases and aerosols, by 2100 temperatures in
Virginia could increase by 3°F in winter, spring, and summer (with
a range of 1-6°F), and 4°F in fall (with a range of 2-8°F). Precipita-
tion is estimated to increase by 20% in all seasons (with a range
of 10-30%). Other climate models may show different results.
especially  regarding estimated changes in precipitation. The
impacts described in the sections that follow  take into account
estimates from different models. The frequency of extreme hot
days in summer would increase because of the general warming
trend. Although it is not clear how the severity of storms such as
hurricanes might be affected, an increase in the frequency and
intensity of winter storms is possible.
     Precipitation Trends From  1900 To Present
 Trends/100 years
Source: Karl et al. (1996)

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Human Health

Higher temperatures and increased frequency of heat waves may
increase the number of heat-related deaths and the incidence of
heat-related illnesses. Virginia, with its irregular, intense heat
waves, could be susceptible. To the south, one study projects
increases of nearly 70% given a warming of 3 -4°F (although
increased air conditioning use may not have been fully accounted
for). However, heat-related deaths could increase slightly around
and north of Washington, D.C. This study also projects that
winter-related deaths could remain unaffected in the southern
part of the state, but could rise by a third in the northern part of
the state near Washington, D.C. The elderly, especially those
living alone, are at greatest risk. The exact reasons for these
differences are unknown.

Climate change could increase concentrations of ground-level
ozone. For example, high temperatures, strong sunlight, and
stable air masses tend to increase urban ozone levels. In the
eastern mid-Atlantic region, a 4°F warming, with no other change
in weather or emissions, could increase concentrations of ozone.
a major component of smog, by 4%. Currently, ground-level
concentrations exceed the national ozone health standard at
several locations throughout the state. These  areas include the
"serious nonattainment areas" near Washington, D.C. Ground-
level ozone is associated with respiratory illnesses such as
asthma, reduced lung function, and respiratory inflammation.

Warm waters encourage a shift in species from plankton to toxic
algae associated with human shellfish poisoning and fish kills.
Mosquitos carrying malaria, dengue fever, and St. Louis encepha-
litis are present in Virginia. Warm, wet conditions could increase
mosquito populations, increase biting rates, and reduce the
incubation rate of the viruses and parasites within them, perhaps
leading to increased risk of disease transmission where these
diseases are introduced into the area. Rodent populations that
carry hantavirus and leptospirosis (a bacterium) are sensitive
to climatic factors. Drought can reduce rodent predators (owls.
snakes, coyotes), and sudden rains can increase the number
of rodents.

Developed countries such as the United States should be able to
minimize the impacts of these diseases through existing disease
prevention and control methods.


Coastal Areas

Sea level rise could lead to flooding of low-lying property, loss
of coastal wetlands, erosion of beaches, saltwater contamination
of drinking water, and decreased longevity of low-lying roads.
causeways, and bridges. In addition, sea level rise could
increase the vulnerability of coastal areas to storms and
associated flooding.

Virginia is endowed with over 3,300 miles of tidally influenced
shoreline. It consists of barrier islands, the sandy beaches of
the Delmarva peninsula, as well as the western shore of
Chesapeake Bay, the nation's largest estuary.  The western shore
of Chesapeake Bay features a diversity of tidally influenced
wetlands, including freshwater and flooded hardwood marshes.
      Future Sea Level Rise At Newport News
110
100
90
80




30
20
n
5% Chance — i—
50% Chance — —
- 90% Chance -I—





±







	






	




	

                               Year
      Source: EPA (1995)
brackish marshes, and riverine wetlands. Because of human
activities such as dredging, as well as a slow natural rate of
sediment accretion, rising sea levels are likely to increase inunda-
tion and salinity intrusion in these ecosystems. Virginia's existing
barrier beaches are currently eroding rapidly (tens of feet per
year). If sea level were to rise 3 feet or more, Virginia's existing
barrier beaches could disappear, causing further erosion of salt
marshes.

At Newport News, sea level already is rising by 12 inches per
century, and it is likely to rise another 23.3 inches by 2100. The
cumulative cost of sand replenishment to protect Virginia's
coastline from a 20-inch sea level rise by 2100 is estimated at $200
million to $1.2billion.
Water  Resources

In the mountainous portions of the state, winter warming could
cause more of the precipitation to fall as rain. In other areas of the
state, without increases in rainfall, higher temperatures and
evaporation in the summer would also cause drier summer
conditions. This could result in lower streamflows, lake levels.
and groundwater levels. In densely populated areas along the
James and Roanoke rivers, competition for water to meet public
and industrial needs could increase. Groundwater levels in the
coastal plain also could decline further. Warmer temperatures
could increase water quality problems such as algae and
eutrophication.

If rainfall and runoff increase with a warmer climate, many of these
problems would be reduced. However, this could
lead to increased problems from flooding, particularly in the
Appalachian region. Higher rainfall also could increase erosion
and runoff of pollutants from agricultural, urban, and mining
areas, and could increase concentrations of fertilizers, heavy
metals, and organic substances. The rivers of Virginia currently
receive large amounts of chemicals from farming, including
fertilizers. These chemicals reduce oxygen and limit the types of
species that can live in the rivers. Increased runoff from farmlands
would exacerbate this effect. These already are a concern in the
sediments of the  James and Shenandoah rivers and in
estuaries along Chesapeake Bay.

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   Changes In Agricultural Yield And  Production
             Dryland Yield                  Production
          Corn  Soybeans  Hay
           • AT = 7°F;Aprecip. =
  Com Soybeans  Hay
|AT = 8°F;Aprecip. = 5%
Sources: Mendelsohn and Neumann (in press); McCarl (per-
sonal communication)

Agriculture

The mix of crop and livestock production in a state is influenced
by climatic conditions and water availability. As climate warms.
production patterns could shift northward. Increases in climate
variability could make adaptation by farmers more difficult.
Warmer climates and less soil moisture due to increased evapora-
tion may increase the need for irrigation. However, these same
conditions could decrease water supplies, which also may be
needed by natural ecosystems, urban populations, industry, and
other users.

Understandably, most studies have not fully accounted for
changes in climate variability, water availability, crop pests.
changes in air pollution such as ozone, and adaptation by farmers
to changing climate. Including these factors could change
modeling results substantially. Analyses that assume changes in
average climate and effective adaptation by farmers suggest that
aggregate U.S. food production would not be harmed, although
there may be significant regional changes.

In Virginia, production agriculture is a $2 billion annual industry.
two-thirds of which comes from livestock. Very few of the farmed
acres are irrigated. The major crops in the state are corn, soy-
beans, hay, and tobacco.  Crop and pasture yields could fall by as
much as 36% under severe conditions where temperatures rise
beyond the tolerance levels of the crop, or could rise by  19%.
depending on how climate changes. Farmed acres are projected to
remain fairly constant. Estimated changes in yield vary, depend-
ing on whether land is irrigated. Livestock and  dairy production
may not be affected, unless summer temperature rises signifi-
cantly and conditions become significantly drier. Under these
conditions, livestock tends to gain less weight  and pasture yields
decline, limiting forage.
current range of forests could be reduced and replaced by
grasslands and pasture. Even a warmer and wetter climate could
lead to changes; trees that are better adapted to warmer condi-
tions, such as southern pines, would prevail. Under these
conditions, forests could become more dense. These changes
could occur during the lifetimes of today's children, particularly if
the change is accelerated by other stresses such as fire, pests,
and diseases. Some of these stresses would themselves be
worsened by a warmer and drier climate.

With changes in climate, the extent and density of forested areas
in Virginia could change little or decline by as much as 5 -10%.
However, the types of trees dominating those forests are likely to
change.  The warmer mixed forests, dominated by southern pines
and oaks, would spread northward, replacing the predominantly
hardwood forests  currently found in the northern and western
sections of the state. Maritime forests, important for their
recreational and aesthetic value and for their role in coastal
hydrology, could be affected adversely by changes in the
frequencies of large storms associated with climate change
(hurricanes in the late summer and fall, nor'easters in the winter
and spring).


Ecosystems

High-elevation sites of the southern Appalachians in Virginia
contain remnants  of northern forests such as red spruce and
Fraser fir trees. Birds normally associated with forests far to the
north, such as the  Canada and Blackburnian warblers, inhabit
these forest types. Another valuable ecosystem is the eastern
shore, which has been designated a priority watershed. This
coastal area contains barrier reefs and tidal marshes, which are
important habitat for three endangered species (loggerhead sea
turtles, peregrine falcons, and piping plovers).

The Appalachian spruce-fir forests are already threatened by
air pollution (acid rain and ground-level ozone) and exotic pests
(hemlock wooly adelgid). These forests could be further  stressed
by climate change as conditions suitable for  growth of red spruce
and Fraser fir decline with warmer and drier conditions. The
southern Appalachians are a globally important center of
diversity for salamanders, which are very sensitive to climatic
factors. Recent changes in salamander community structure have
already been documented on Hawksbill Mountain in the
Shenandoah National Park, where the red-backed salamander
(widely distributed in North America) is increasing its range at the
expense of the endangered Shenandoah salamander. Climate
change could hasten this change. Warmer air temperatures could
lead to reduced stream flow and warmer water temperatures.
which could impair reproduction offish such as the brook trout.
In coastal habitats, one consequence of rising sea levels will be
the inundation and salinization of vital wildlife habitats.
Forests

Trees and forests are adapted to specific climate conditions.
and as climate warms, forests will change. These changes could
include changes in species composition, geographic range, and
health and productivity. If conditions also become drier, the
                           For further information about the potential impacts of climate
                           change,  contact the Climate and Policy Assessment Division
                           (2174), U.S. EPA, 401 M Street SW, Washington, DC 20460, or
                           visit http://www. epa.gov/globalwarming/impacts.

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