4%	United States	August 2016
MPnl Environmental Protection
w^m Ifl Age n cy	EPA 430-F-16-048
What Climate Change
Virginia's climate is changing. Most of the state has
warmed about one degree (F) in the last century, and
the sea is rising one to two inches every decade. Higher
water levels are eroding beaches, submerging low lands,
exacerbating coastal flooding, and increasing the salinity
of estuaries and aquifers. The southeastern United States
has warmed less than most of the nation. But in the
coming decades, the region's changing climate is likeiy
to reduce crop yields, harm livestock, increase the
number of unpleasantly hot days, and increase the risk
of heat stroke and other heat-related illnesses.
Our climate is changing because the earth is warming.
People have increased the amount of carbon dioxide in
the air by 40 percent since the late 1700s. Other heat-
trapping greenhouse gases are also increasing. These
gases have warmed the surface and lower atmosphere of
our planet about one degree during the last 50 years.
Evaporation increases as the atmosphere warms, which
increases humidity, average rainfall, and the frequency of
heavy rainstorms in many places—but contributes to
drought in others.
Greenhouse gases are also changing the world's oceans
and ice cover. Carbon dioxide reacts with water to form
carbonic acid, so the oceans are becoming more acidic.
The surface of the ocean has warmed about one degree
during the last 80 years. Warming is causing snow to melt
earlier in spring, and mountain glaciers are retreating.
Even the great ice sheets on Greenland and Antarctica are
shrinking. Thus the sea is rising at an increasing rate.
Temperature change (°F):
-1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5
Rising temperatures in the last ccntuiy. The eastern half of
Virginia has wamed more than the western half. Source: EPA,
Climate Change Indicators in the United States.
Rising Seas and Retreating Shores
Sea level is rising more rapidly along Virginia's shores than in most
coastal areas because the land is sinking. If the oceans and atmo-
sphere continue to warm, sea level along the Virginia coast is likely to
rise sixteen inches to four feet in the next century.
Oceanfront houses in Virginia Beach are vulnerable to severe storms,
flooding, and coastal erosion. © James G. Titus; used by permission.
As sea level rises, the lowest dry lands are submerged and become
either tidal wetland or open water. The freshwater wetlands in the
upper tidal portions of the Potomac, Rappahannock, York, and James
rivers build their own land by capturing floating sediments, and they
are likely to keep pace with the rising sea during the next century.
But most salt marshes along the brackish portions of those rivers
and along Chesapeake Bay are unlikely to keep pace if sea level rises
three feet. The wetlands of Back Bay and the North Landing River are
even more vulnerable and may be lost if the sea rises two feet.
Beaches also erode as sea level rises. A higher ocean level makes
it more likeiy that storm waters will wash over a barrier island or
open new inlets. The United States Geological Survey estimates that
Virginia's barrier islands could be broken up by new inlets or lost to
erosion if sea level rises two feet by the year 2100. Beach erosion will
threaten the oceanfront portion of Virginia Beach, unless people take
measures to offset the erosion. Rising sea level also threatens bay
beaches and tidal flats.
Saltwater Intrusion
As sea level rises, salt water can mix farther inland or upstream in
bays, rivers, and wetlands. Because water on the surface is connect-
ed to ground water, salt water can also intrude into aquifers near the
coast. Soils may become too salty for farms or forests. For example,
some of the freshwater swamps along the York River's tidal tributar-
ies have standing dead trees that were killed by saltwater intrusion
made possible by rising sea level.

Storms, Homes, and Infrastructure
Tropical storms and hurricanes have become more intense
during the past 20 years. Although warming oceans provide
these storms with more potential energy, scientists are not sure
whether the recent intensification reflects a long-term trend.
Nevertheless, hurricane wind speeds and rainfall rates are likely
to increase as the climate continues to warm.
Whether or not storms become more intense, coastal homes and
infrastructure will flood more often as sea level rises, because
storm surges will become higher as well. Many roads, railways,
and ports are vulnerable to the impacts of storms and sea level
rise, and most of the heavily populated Hampton Roads area
could be flooded by a major hurricane. Poquoson and a few other
communities along Chesapeake Bay are so low that water in
roadside ditches rises and falls with the tides. As sea level rises
and storms possibly become more severe, homes and infrastruc-
ture in these communities will flood more frequently. As a result,
rising sea level is likely to increase flood insurance rates, while
more frequent storms could increase the deductible for wind
damage in homeowner insurance policies.
Increased rainfall could further exacerbate flooding in both
coastal and inland areas. The amount of precipitation during
very heavy storms increased by 27 percent between 1958
and 2012 in the Southeast, and the trend toward increasingly
severe rainstorms is likely to continue.
The rising sea threatens low-lying coastal towns such as Tangier,
which is less than five feet above sea level. © James G. Titus; used by
Coastal Ecosystems
The loss of tidal marshes could harm fish and birds that depend
on a marsh for food or shelter. Marine organisms and small
insects that feed in marshes are key sources of food for crabs,
rockfish, and other commercially important fisheries. Striped
bass, bluefish, sea trout, and summer flounder move into and
out of marshes for food and shelter. Many birds inhabit the most
vulnerable marshes along Chesapeake Bay, including great blue
heron, bald eagle, American black duck, and snowy egret.
Marshes along the Atlantic coast provide forage for shorebirds,
such as sandpipers and plovers, and several species of ducks
and geese spend the winter in these marshes.
The loss of bay beaches would remove key habitat for diamond-
back terrapin, which nest on these beaches. Other species that
depend on bay beaches include horseshoe crabs, tiger beetles,
sand fleas, snails, and several crab species. The loss of those
species would remove important sources of food for birds.
Changing temperatures could also disrupt ecosystems. If water
temperatures exceed 86°F during summer, eelgrass could be
lost, which would remove habitat for summer flounder, blue crab,
and bay scallop. Brants, canvasback ducks, and American black
ducks would also lose a food source.
Changing the climate will have both harmful and beneficial
effects on farming. Higher temperatures are likely to reduce
livestock productivity, because heat stress disrupts the animals'
metabolism. In the next few decades, hotter summers are likely
to reduce yields of corn. But higher concentrations of
atmospheric carbon dioxide increase crop yields, and that
fertilizing effect is likely to offset the harmful effects of heat on
cotton, soybeans, wheat, and peanuts—assuming that adequate
water is available. Rising temperatures are likely to increase the
need for irrigation, and where water is scarce, increasingly
severe droughts are likely to reduce crop yields.
Seventy years from now, temperatures are likely to rise above
95°F approximately 20 to 40 days per year in the southeastern
half of Virginia, compared with about 10 days per year today.
Warmer temperatures will increase the use of air-conditioning,
which will increase electricity consumption.
Human Health
Hot days can be unhealthy—even dangerous. Certain people are
especially vulnerable, including children, the elderly, the sick,
and the poor. High air temperatures can cause heat stroke and
dehydration, and affect people's cardiovascular and nervous
systems. Warmer temperatures can also increase the formation
of ground-level ozone, a key component of smog. Because ozone
has a variety of health effects, aggravates lung diseases such as
asthma, and increases the risk of premature death from heart or
lung disease, EPA and the Virginia Department of Environmental
Quality have been working to reduce ozone concentrations. As
the climate changes, continued progress toward clean air will be
more difficult.
The sources of information about ciimate and the impacts of climate change in this publication are: the national climate assessments by the U.S. Global Change
Research Program, synthesis and assessment products by the U.S. Climate Change Science Program, assessment reports by the Intergovernmental Panel on Climate
Change, and EPA's Climate Change Indicators in the United States. Mention of a particular season, location, species, or any other aspect of an impact does not imply
anything about the likelihood or importance of aspects that are not mentioned. For more Information about climate change science, Impacts, responses, and what you
can do, visit EPA's Climate Change website at www.epa.aov/climatechanae.