United States
Environmental Protection
Agency
Office of Policy
(2111)
EPA 236-F-98-007q
September 1998
wEFA Climate Change And North 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 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)
-0.2
-0.4
-0.6
-0.8
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regular, intense heat during a typical summer, one study suggests
that the population could still be sensitive to heat waves.
In Greensboro, a warming of 3 °F during a typical summer
is estimated to increase heat-related deaths by nearly 70%, from
about 20 to about 35 (although increased air conditioning use
may not have been fully accounted for).
Infected individuals can bring malaria to places where it does
not occur naturally. Also, some mosquitoes in North Carolina can
carry malaria, and others can carry California and eastern equine
encephalitis, which can be lethal or cause neurological damage.
If conditions become warmer and wetter, mosquito populations
could increase, thus increasing the potential for transmission if
these diseases are introduced into the area. 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.
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 contami-
nation 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 associ-
ated flooding.
North Carolina has a 3,375-mile tidally influenced shoreline.
consisting of a long chain of barrier islands, including the Outer
Banks, and extensive salt marshes and tidal freshwater marshes
that have formed behind these barrier islands.
As sea level rises, coastal marshes may initially expand by
spreading onto low-lying terraces, particularly in and around
Albemarle Sound. Further changes in the extent of coastal
wetlands will vary with location, with significant loss of wetlands
Future Sea Level Rise At Long Bay
uu
90
80
70
30
n
- 5% Chance
_ 50% Chance
90% Chance
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J
±
-
—
2050
Source: EPA (1995)
2100 2150
Year
2200
possible in some areas. North Carolina has experienced more
direct hurricane strikes than any other Atlantic coast state except
Florida, and the coast could be susceptible to additional damages
from hurricanes as higher sea levels increase the vulnerability of
some areas to storm surge.
At Long Bay, sea level already is rising by approximately 2 inches
per century, and it is likely to rise another 12 inches by 2100. The
cumulative cost of sand replenishment to protect the coast of
North Carolina from a 20-inch sea level rise by 2100 is estimated at
$660 million to $3.6 billion. However, sand replenishment may not
be cost-effective for all coastal areas of the state, and therefore
some savings could be possible.
Water Resources
Concerns about water demand exceeding supply could increase
for growing cities such as Gary, Chapel Hill, Greensboro, and
Asheville. Lower flows and higher water temperatures also could
degrade water quality by concentrating pollutant levels and
reducing the assimilation of wastes. This could affect rivers such
as the Catawba River, which not only supplies water for Charlotte
and other large cities but also receives the waste discharges from
many municipalities and industries. Aquifers in the Coastal
Plains, which currently suffer from declining levels and saltwater
intrusion, could be diminished further. Irrigation from ground-
water, which serves as an important source of water during
drought periods in the Coastal Plains, also could be adversely
affected.
Increased precipitation could alleviate water supply problems
and provide more water for dilution of pollutants, but it also could
increase flooding. In the mountainous areas of western North
Carolina, where stream slopes are steep and flash flooding is
common, recent development in floodplain areas would be
especially vulnerable to floods. Pollution of streams, lakes, and
estuaries by toxins, nutrients, and sediment is a primary water
quality concern in the state. Higher rainfall could increase erosion
and exacerbate levels of pesticides and fertilizers in runoff from
agricultural areas. It also could increase pollution in runoff from
mining and urban areas. Additionally, higher streamflows could
exacerbate problems in low-lying coastal areas being developed
for agriculture and peat mining.
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
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Changes In Agricultural Yield And Production
Dryland Yield Production
Corn Soybeans Wheat Corn Soybeans Wheat
• AT = 7°F; Aprecip. = 11% • AT = 8°F; Aprecip. = 3%
Sources: Mendelsohn and Neumann (in press); McCarl (per-
sonal communication)
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 North Carolina, production agriculture is a $5.4 billion
annual industry, 60% of which comes from livestock. Very few
of the farmed acres are irrigated. The major crops in the state are
corn, wheat, hay, and tobacco. Soybean and wheat yields could
decrease as a result of climate change, with soybeans falling by
3-39% and wheat by 5-11% as temperatures rise beyond the
tolerance level of the crop. Corn yields could fall by 28% or rise
by 7%, depending on how climate changes. Estimated changes in
yield vary, depending on whether land is irrigated. Farmed acres
are projected to remain fairly constant based on estimated
changes in production and prices. Livestock and dairy produc-
tion 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.
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
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. Commercial timber
production could also be affected by resulting changes in growth
rates, plantation acreage and management, and market conditions.
With changes in climate, the extent and density of forested
areas in North Carolina could change little or decline by 5-10%.
However, the types of trees dominating those forests are likely to
change. The warmer mixed forests, dominated by southern pines
and oaks, could spread northward, replacing the predominantly
hardwood forests of the north and west. The forests of western
North Carolina in and around the Great Smoky Mountains
National Park support a rich variety of plants and animals, and
they are important recreation areas. Composition changes in
these forests could adversely affect diversity and recreation.
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 (hurri-
canes in the late summer and fall, nor'easters in the winter and
spring). Warmer and drier conditions could increase the fre-
quency 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.
Ecosystems
Valuable ecosystems in North Carolina include spruce-fir
forests, bogs, and unvegetated hilltops in the mountainous
regions; bottomland hardwood forests and fire-maintained
prairies in the piedmont; and longleaf pine forests, Carolina bays.
swamps, and maritime forests in the coastal plain. These provide
critical habitat for numerous native plants and animals, including
53 endangered species. The coast contains estuarine wetlands,
where freshwater, saltwater, and terrestrial ecosystems are home
to endangered species such as bald eagles, piping plovers, and
several species of sea turtles. The Smoky Mountains have long
been recognized as a global center of biodiversity. The highest
peaks are home to 95 species of plants, including Fraser fir trees.
and they provide habitat for animals that are typically found
farther north, such as Carolina northern flying squirrels, Canada
and Blackburnian warblers, and bog turtles. The southern
Appalachians also contain a diverse array of salamanders.
which are very sensitive to climatic factors.
Warmer temperatures could lead to reduced stream flow and
warmer water temperatures, which could significantly impair
reproduction of fish such as the brook trout. With an increase in
average temperatures, the distribution of this species and others
could be reduced and their range could become more limited.
In coastal habitats, one consequence of rising sea levels will be
inundation, salinization, and sedimentation of vital wildlife
habitats. Rising sea levels will result in further inland penetration
of saltwater, and many of the 150 streams and rivers that flow into
the ocean could be adversely affected. The Appalachian spruce-
fir forests are already threatened by air pollution (acid rain and
ground-level ozone) and exotic pests (hemlock wooly adelgid).
Warmer and drier conditions could result in significant loss of red
spruce forests as conditions suitable for the growth of red spruce
and Fraser fir decline.
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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