Climate Change
Climate change will
affect natures ecosystems
and the habitats that
support life—from oceans
to grasslands to forests.
Changes are expected
to alter the makeup
and functioning of
ecosystems, as well as
some of the critical
benefits that ecosystems
provide to people.
Climate change can
threaten ecosystems
that have already been
weakened by other
human activities such as
pollution, development,
and overharvesting.
This fact sheet describes
some of the ways that
climate change affects
   Climate change can have broad effects on biodiversity (the number and variety of plant and anima species
   in a particuar location). Although species have adapted to environmental change for millions of years,
   a quickly changing climate could require adaptation on larger and faster sea es than in the past. Those
   species that cannot adapt are at risk of extinction. Even the loss of a single species can have cascading
   effects because organisms are connected through food webs and other interactions.

   The oceans and the atmosphere are constantly interacting—
   exchanging heat, water, gases, and particles. As the
   atmosphere warms, the ocean absorbs some of this heat. The
   amount of heat stored by the ocean affects the temperature of
   the ocean both at the surface and at great depths. Warming
   of the Earth's oceans can affect and change the habitat and
   food supplies for many kinds of marine life—from plankton to
   polar bears.
   The oceans also absorb carbon dioxide from the atmosphere.
   Once it dissolves in the ocean, carbon dioxide reacts with
   sea water to form carbonic acid. As people put more carbon
   dioxide into the atmosphere,  the oceans absorb some  of this
   extra carbon dioxide, which  leads to more carbonic acid. An
   increasingly acidic ocean can have negative effects on marine
   life, such as cora reefs.

   Although some forests may derive near-term benefits from  an
   extended growing season, climate change is also expected to
   encourage wildfires  by extending the length of the summer fire season. Longer periods of hot weather could
   stress trees, and make them more susceptible to wildfires,  insect damage, and disease. Climate change has
    ikely already increased the size and number of forest fires, insect outbreaks, and tree deaths, particularly
   in Alaska and the West. The area burned in western U.S. forests from 1987 to 2003 is almost seven times
   larger than the area burned from 1970 to 1986. In the last 30 years, the length of the wildfire  season in
   the West has increased by 78 days.
    United States
    Environmental Protection
      What Is an Ecosystem?
      An ecosystem is an interdependent system of plants, animals, and microorganisms
      interacting with one another and with their physical environment. An ecosystem
      can be as large as the Mojave Desert or as small as a local  pond. Ecosystems
      provide people with food, goods, medicines,  and many other products. They also
      play a vital role in nutrient cycling, water purification, and climate moderation.

    Most plants and anima s prefer to live in a particular habitat with a specific temperature range and
    amount of precipitation. Climate change will alter, and in some cases destroy, certain types of habitats.
    For example,  melting sea ice is eliminating an important  habitat for several Arctic species. Mangroves anc
    other coastal  wetlands, which are critical to many species,  are at risk of disappearing because of sea
    level rise. Some species will be able to adapt to changing  habitats—for example, by shifting their range
    northward or  to higher altitudes in order to adjust to rising temperatures.  Others, however, might not be
    able to adapt fast enough to keep pace with the rate of  climate change.

Invasive Species
    As temperature, precipitation, and other conditions change, the species  best suited to the new conditions
    will thrive, often taking food and resources away from others. Some of the species that thrive might be
    invasive (not native to a region) and could gradually drive out or  even kill native species.
Migrations and Life
Cycle Events
    The timing of many natural
    events, such as flower blooms
    and animal migrations, is
     inked to climate factors such
    as temperature, moisture
    availability, and amount of
    daylight. Changes in weather
    patterns and extreme events
    associated with climate change
    can disrupt these natural
    patterns. These disruptions,
    in turn, can affect seasonal
    behavior and interactions
    among species. For example,
    if birds migrate and lay eggs
    too early, hatchlings might not
    have an adequate food supply.
    While some animals and plants
    will successfully adjust life-cycle
    patterns to changing weather
    pattern cues, others might not be
    so successful.
Northward Shift of Bird Migrations,
Source: National Audubon Society.

Hundreds of species of birds in North America are wintering
farther north in recent years.
                              For  More Information
                   For detailed information about greenhouse gas emissions,
                       the effects of climate change, EPA efforts underway,
                    and tips on what you can do, visit EPA's Climate Change
                           Web site