Biodiversity

Climate change can have broad effects on biodiversity (the number and variety of plant and animal species 

in a particular location). Although species have adapted to environmental change for millions of years, 

a quickly changing climate could require adaptation on larger and faster scales 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.

Oceans 

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 coral reefs. 

Forests

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 

likely 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. 

Climate change will 

affect nature’s 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 

ecosystems.

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. 

Climate Change

and Ecosystems

Office of Air and Radiation (6207J) 

EPA 430-F-10-004

www.epa.gov/climatechange 

April 2010 
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 at www.epa.gov/climatechange.

Habitat

Most plants and animals 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 and 

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 

linked 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.

Year

-20

-10

0

10

20

30

40

50

60

1965 1970 1975 1980 1985 1990 1995 2000 2005

Average distance moved north (miles)

Northward Shift of Bird Migrations, 

1966–2005

Hundreds of species of birds in North America are wintering 

farther north in recent years.

Source: National Audubon Society. 2009. www.audubon.org/bird/bacc/techreport.html