CLIMATE CHANGE
I housands of scientists predict
that the earth's climate will
change because human activities
are altering the chemical composi-
tion of the atmosphere through
the buildup of greenhouse gases.
The heat-trapping property of such
gases as carbon dioxide, methane,
nitrous oxide, and chloroflurocar-
bons is undisputed. Greenhouse
gases are released into the atmos-
phere in large quantities by
motorized vehicles, utilities, facto-
ries, appliances, and landfills.
Although there is uncertainty
about exactly how and when the
earth's climate will respond to
higher concentrations of green-
house gases, observations indi-
cate that detectable changes are
underway. Temperatures will
most likely rise by an average of
2 to 6°F over the next century,
along with measurable changes
in precipitation, soil moisture,
and sea level. All of these
changes could have adverse
effects on many ecological sys-
tems, as well as on human
health and the economy.
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WHAT CAN YOU DO?
Inform yourself and other. To keep
up with the Latest scientific
developments, check out EPA's
climate change website at
www.epa.gov/globalwarming. Or
call EPA's National Service Center for
Environmental Publications (NSCEP)
at 1-800-490-9198 and ask for
information on climate change.
Encourage more research. If you work for
an organization that carries out related
scientific studies, suggest including a
dimate change component to the research.
Reduce greenhouse gases. Use a more
fuel-efficient (or non-motorized) mode
of transportation. CarpooL Purchase
electronic devices and appliances with the
ENERGY STAR* label Plant trees.
&EPA
U.S. ENVIRONMENTAL
PROTECTION AGENCY
Office of Policy (2171)
401 M Street, SW
Washington, DC 20460
& $ Printed on Recycled Paper
United States
Environmental Protection
Agency
Office of Policy (2171)
EPA-236-F-99-003
May 1999
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Cl IMAT [ CHANGE
CLIMATE CHANGE
Global warming could affect the
abundance and distribution of birds
in the United States. Changes in cli-
mate may change nesting and feeding
habitats, migratory stopover areas,
and the availability of key food
sources. Some impacts may be posi-
tive, making conditions more favor-
able for certain kinds of birds. But
climate change also could lead to
reduced breeding success in some
species and some localities, raising
the possibility of regional population
declines and extinctions.
Birds require specific environmental
conditions to survive and raise their
young. Nesting, for example, is timed
to coincide with favorable weather
and food availability. If a trend
toward warmer spring weather leads
birds to nest earlier, their breeding
success may suffer if primary food
sources are not yet available when
nestlings hatch.
Birds are more mobile than most
other animals, and they simply can
fly to a new location if a former site
is no longer suitable. But global
warming may make it difficult for
some species to find new habitats.
Plant and animal communities that
provide optimal habitat today may be
fundamentally altered in the future as
the climate changes. A recent study
suggests that ecological communities
may not simply shift their range
northward in response to warming,
but instead may undergo complex
changes as interacting species are
affected in different ways by the
changing climate.
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Changes in temperature and precipi-
tation predicted under global warm-
ing could affect the nesting habitats
of ducks and other waterfowl. Accord-
ing to one study, global warming could
cause breeding populations of ducks in
the north-central United States to
decline by more than half—from 5 mil-
lion birds today to between 2.1 and
2.7 million by the year 2060.
Why? Warmer temperatures and more
frequent droughts could cause hun-
dreds of thousands of ponds in the
prairie pothole region of the north-
central U.S. to dry up. The potholes
account for only 10 percent of North
America's waterfowl breeding habitat,
but they produce 50 to 80 percent of
the continent's ducks. The pothole
region also serves as an important
stopover point for migrating water-
fowl. Although many of the affected
ducks may move north into Canada,
studies suggest that climate change
may affect breeding habitats in
Canadian prairies and forests as well.
Populations of sooty shearwaters off
the coast of California and Washington
declined by 90 percent between 1987
and 1994, a period when sea surface
temperatures increased. The decline
represents a potential loss of more
than 4 million birds. The warmer water
triggers a reduction in upwelling, a
circulatory process that brings nutri-
ent-rich water to the ocean's surface.
Over the past two decades, reduced
upwelling apparently has caused a 70
percent decrease in zooplankton, a key
food source for shearwaters and the
small fish that the shearwaters eat.
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