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Causes of Climate Change

Climate change is a term that refers to major changes in temperature, rainfall, snow, or wind patterns for decades or longer. Both human-made and natural factors contribute to climate change:

Human causesinclude burning fossil fuels, cutting down forests, and developing land for farms, and roads. These activities all release greenhouse gases into the atmosphere.

Natural causesinclude changes in the Earths orbit, the suns intensity, the circulation of the oceathe atmosphere, and volcanic activity.

Although the Earths climate has changed many times throughout its history, the rapid warming seen todacannot be explained by natural processes alone.

Human activities are increasing the amount ofgreenhouse gases in the atmosphere. Someamount of greenhouse gases is necessaryfor life to exist on Earththey trap heat inthe atmosphere, keeping the planet warmand in a state of equilibrium. But this naturalgreenhouse effect is being strengthened ashuman activities (such as the combustion offossil fuels) add more of these gases to the atmosphere, resulting in a shift in the Earths equilibrium.

Climate Change ScienceFacts

Climate change is

a real and urgent

hallenge that is already

affecting people and the

nvironment worldwide.

Significant changes are

occurring on Earth,

ncluding increasing air

and ocean temperatures,

widespread melting of

now and ice, and rising

ea levels. This fact sheet

discusses key scientific

facts that explain the

auses and effects of

limate change today,

as well as projections for

he future.

Office of Air and Radiation (6207J)EPA 430-F-10-002www.epa.gov/climatechangeApril 2010

Heat-trapping greenhouse gases are now

at record-high levels in the atmosphere

compared with the recent and distant pas

1850 1870 1890 1910 1930 1950 1970 1990 2010260

280

300

320

340

360

380

400

Atmos

phericCarbonDioxideConcentration(ppm)

-1

-0.5

0

0.5

1

1.5

Tem

peratureDifferencefromB

aseline(F)

Carbon Dioxide ConcentrationGlobal Temperature

1901-2000 Average Temperature

Year

The Link Between Greenhouse Gases and Temperature,

18502009

Emissions of carbon dioxide, an important greenhouse gas, have been increasingsince the Industrial Revolution. These emissions are causing carbon dioxide levels tobuild up in the atmosphere and global temperatures to rise. In particular, temperatureshave gone up at an increased rate over the past 30 years. Carbon dioxide datain this figure are compiled from several different studies. Temperature data show thedifference from the average or baseline temperature between 1901 and 2000.

Source: Carbon Dioxide Information Analysis Center. 2010. http://cdiac.ornl.gov/ and

National Oceanic and Atmospheric Administration. 2010.www.noaa.gov

http://www.noaa.gov/http://www.noaa.gov/

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Signs of Climate Change

Climate change is happening now, and the effects can be seen on every continent and in every oceaWhile certain effects of climate change can be beneficial, particularly in the short term, current and fueffects of climate change pose considerable risks to peoples health and welfare, and the environmen

There is now clear evidence that the Earths climate is warming:

Global surface temperatures have risen by 1.3 degrees Fahrenheit (F) over the last 100 years.

Worldwide, the last decade has been the warmest on record.

The rate of warming across the globe over the last 50 years (0.24F per decade) is almost doubrate of warming over the last 100 years (0.13F per decade).

The evidence of climatechange extends wellbeyond increasesin global surfacetemperatures. It alsoincludes:

Changingprecipitation patterns.

Melting ice in theArctic.

Melting glaciersaround the world.

Increasing ocean

temperatures. Rising sea level

around the world.

Acidification ofthe oceans due toelevated carbondioxide in theatmosphere.

Responses by plantsand animals, such asshifting ranges.

Projections of Climate ChangeAt the current rate, the Earths global average temperature is projected to rise f rom 3 to 7F by 2100,it will get even warmer af ter that. As the climate continues to warm, more changes are expected to ocand many effects will become more pronounced over time. For example, heat waves are expected tobecome more common, severe, and longer lasting. Some storms are likely to become stronger and mfrequent, increasing the chances of flooding and damage in coastal communities.

Climate change will affect different regions, ecosystems, and sectors of the economy in many ways,depending not only on the sensitivity of those systems to climate change, but also on their ability toadapt to risks and changing conditions. Throughout history, societies and ecosystems alike have showremarkable capacity to respond to risks and adapt to different climates and environmental changes.Today, effects of climate change have already been observed, and the rate of warming has increaserecent decades.

For this reason, human-caused climate change represents a serious challengeone that could require

approaches and ways of thinking to ensure the continued health, welfare, and productivity of society the natural environment.

Year

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 201

Temperatureanomaly(F)

-3

-2

-1

0

1

2

3

19012009 trend: +1.25F per century

19792009 trend: Surface: +5.05F per century UAH: +4.00F per century RSS:+3.49F per century

Earth's surface Lower troposphere (measured by satellite)

UAH RSS

Temperatures in the Lower 48 States,

19012009

Since 1901, temperatures have risen across the lower 48 states atan average rate of 0.13F per decade (1.3F per century). Averagtemperatures have risen more quickly since the late 1970s.

Source: National Oceanic and Atmospheric Administration. 2010.

www.ncdc.noaa.gov/oa/ncdc.html

As the climate

continues to warm,

more changes are

expected to occur

and many effectswill become more

pronounced over

time.

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 EPAs Climate ChangeWeb site atwww.epa.gov/climatechange.

http://www.epa.gov/climatechangehttp://www.epa.gov/climatechange