United States
                    Environmental Protection
                            Office of Policy
                           EPA 236-F-98-007W
                           September 1998
                    Climate  Change And  South  Carolina
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 60F. 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
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 0.6-1.2F
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

     Global Temperature Changes (1861-1996)
    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 1.6-6.3F 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 in Columbia.
South Carolina, has increased 1.3F, and precipitation has
increased by up to 20% in many parts of the state. These
past trends may or may not continue into the future.

Over the next century, climate in South Carolina may change even
more. For example, based on projections made by the Intergov-
ernmental Panel on Climate Change and results from the United
KingdomHadley Centre's climate model (HadCM2), a model that
accounts for both greenhouse gases and aerosols, by 2100
temperatures in South Carolina could increase by 3F (with a
range of 1 -5F) in all seasons (slightly less in winter and summer.
slightly more in spring and fall). Precipitation is estimated to
increase by 15% (with a range of 5 -3 0%) in spring, slightly more
in summer and fall, and slightly less in winter. 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. It is not clear how the severity of
storms such as hurricanes might be affected, although an in-
crease in the frequency and intensity of summer thunderstorms is
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. The elderly, particularly those living alone.

     Precipitation Trends From 1900 To Present
                                      Trends/100 years
                                           -5%  O
                                                              Source: Karl et al. (1996)

are at greatest risk. These effects have been studied only for
populations living in urban areas; however, even those in rural
areas may be susceptible.

Infected individuals can bring malaria to places where it does
not occur naturally. Also, some mosquitoes in South Carolina
can carry malaria, and others can carry eastern equine encepha-
litis,  which can be lethal or cause neurological damage. If condi-
tions become warmer and wetter, mosquito populations could
increase, thus increasing the risk of transmission if 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 bring new food supplies
to the rodents. These conditions could be associated with
upsurges of rodent populations. Warmer temperatures could also
increase the incidence of Lyme disease and other tick-borne
diseases in South Carolina, because populations of ticks, and
their rodent hosts, could increase under warmer temperatures
and increased vegetation.

In addition, warmer seas could contribute to the increased
intensity, duration, and extent of harmful algal blooms, that is.
red tides. These blooms damage habitat and shellfish nurseries.
can be toxic to humans, and can carry bacteria like those causing
cholera. Brown algal tides and toxic algal blooms already are
prevalent in the Atlantic. Warmer ocean waters could increase
their occurrence and persistence.

Developed countries such as the United States should be able  to
minimize the impacts of these diseases through existing disease
prevention and control methods.
                  There are 2,876 miles of tidally influenced shoreline in South
                  Carolina. Historical rates of accretion and erosion vary consider-
                  ably across the state's coastline  erosion has been most severe
                  on a 20-mile section of the Grand Strand and parts of the Santee
                  delta, while Kiawah Island is accreting at a rate of 9 feet per year.
                  Erosion is likely to increase under a 1-3 foot rise in sea level. The
                  potential for increased storm damage as a result of sea level rise is
                  particularly high along the densely developed Grand Strand.

                  At Charleston, sea level already is rising by 9 inches per century.
                  and it is likely to rise another  19 inches by 2100. The cumulative
                  cost of sand replenishment to protect the coast of South Carolina
                  from a 20-inch sea level rise by 2100 is estimated at $ 1.2-$9.4
                  billion. However, sand replenishment may not be cost-effective
                  for all coastal areas in the state, and therefore some savings could
                  be possible.

                  Water Resources

                  In northwestern South Carolina, where most of the state's
                  population lives, lower streamflows, lake levels, and groundwater
                  levels could affect the availability of water supplies for industrial.
                  municipal, and recreational activities. Levels could be lowered in
                  the shallow wells which serve the rural population in this region.
                  Along the Coastal Plain, increased groundwater pumping in areas
                  such as Hilton Head-Beaufort and Myrtle Beach has resulted in
                  saltwater intrusion into freshwater aquifers. Increased use of
                  groundwater for irrigated agriculture in the Coastal Plain also has
                  resulted in declining groundwater levels and may have acceler-
                  ated the formation of sinkholes in the region's limestone terrain.
                  These  conditions, particularly if accompanied by sea level rise.
                  could be exacerbated by warmer, drier conditions.
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.
        Future Sea Level Rise At Charleston
    Source: EPA (1995)
2100      2150
                  Lower flows and higher temperatures could worsen current water
                  quality concerns such as the excessive growth of aquatic weeds
                  in lakes and the impacts of wastewater discharges on shellfish
                  harvests and recreation.

                  Higher rainfall could mitigate these effects, but would contribute
                  to localized flooding. Higher rainfall also could increase erosion
                  and exacerbate levels of pesticides and fertilizers in runoff from
                  agricultural areas. It also could increase pollution in runoff from
                  urban areas. The effect of buried hazardous wastes on ground-
                  water quality, particularly in Barnwell County and near the
                  Savannah River Plant, is a concern in South Carolina. Although
                  the effects of climate change on the movement of pollutants are
                  not well understood, changes in infiltration rates  could affect the
                  rate at which pollutants migrate throughout an aquifer. Increased
                  precipitation could contribute to groundwater contamination
                  by increasing the inflow of contaminants into nearby aquifers.

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
evaporation may increase the need for irrigation. However, these

   Changes In Agricultural Yield And  Production
            Dryland Yield                Production
        Corn  Soybeans Wheat
          AT = 7F; Aprecip. = 9%
 Corn  Soybeans Wheat
I AT = 7F; Aprecip. = -2%
Sources: Mendelsohn and Neumann (in press); McCarl (per-
sonal communication)

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 South Carolina, production agriculture is a $ 1.2 billion
annual industry, almost split evenly between crops and livestock.
Very few of the farmed acres are irrigated. The major crops in the
state are corn, soybeans, and wheat. Soybean and wheat yields
could decrease as a result of climate change by 15-42% as tem-
peratures rise beyond the tolerance level of the crop and are
combined with increased stress from decreased soil moisture.
Corn yields could fall by 32% or rise by 7%, depending on how
climate changes. Farmed acres could decrease by as much as
30-40%. Livestock and dairy production may not be affected.
unless summer temperatures rise significantly and conditions
become significantly drier. Under these conditions, livestock tend
to gain less weight and pasture yields decline, limiting forage.


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
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 subtropical evergreens, would prevail over time.
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 them-
selves be worsened by a warmer and drier climate. Commercial
timber production could also be affected by resulting changes in
growth rates, plantation acreage and management, and market

In South Carolina, longleaf and slash pine forests are likely to
expand northward, and could replace some of the forests cur-
rently dominated by loblolly and shortleaf pines. Wetter condi-
tions would favor expansion of oak and hickory deciduous
forests as well as the gum and cypress forests found along the
southeastern seaboard. In contrast, under drier conditions, 10-
15% of the forested areas in the northwestern part of the state
could be replaced by grasslands and pasture. 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). Warmer and drier conditions could increase the
frequency and intensity of fires, and result in increased losses to
important commercial timber areas. Even warmer and wetter
conditions could stress forests by increasing the winter survival
of insect pests.

                              South Carolina is dominated by coastal ecosystems that provide
                              critically important habitat for endangered and threatened species
                              such as the American alligator, Bachman's warbler, bald eagle.
                              brown pelican, loggerhead sea turtle, piping plover, red-cockaded
                              woodpecker, shortnose sturgeon, and woodstork. Important
                              wetland habitats include Carolina bays and pocosins, both of
                              which contain a number of endangered plants, many  with
                              restricted ranges. Terrestrial habitats include large areas of oak-
                              hickory-pine forest and the extreme southern part of the Appala-
                              chian highlands.

                              Sea level rise under a changed climate could threaten many low-
                              lying coastal ecosystems. A study in the Cape Romaine National
                              Wildlife Refuge revealed that at the current rate of sea level rise (9
                              inches per century), the refuge's marshlands and barrier islands
                              could be reduced in size by as much as 58% by 2100. Changes in
                              climate could increase this rate. Endangered birds such as the
                              Bachman's warbler and red-cockaded woodpecker will lose more
                              than 50% of their habitat. The intrusion of seawater from rising
                              seas also will threaten the viability of freshwater systems.
                              Extensive human coastal development is an impenetrable
                              barrier to the landward migration of coastal wetland habitats.

                              A 4F increase in average temperature could substantially
                              reduce brook trout populations in South Carolina, where they
                              are currently at the southern limit of their distribution. Habitat
                              for warm water fish could also be reduced by hotter temperatures.
                              In the forests of the western part of the state, pine seeds  and
                              seedlings, able to tolerate extreme environmental conditions.
                              may come to dominate  hardwood stands at the expense of
                              oak and hickory.

                              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.