How greenhouse gases affect Earth's climate
How greenhouse gases affect Earth's climate
An overview of the role greenhouse gases play in modifying Earth's climate.
Encyclopædia Britannica, Inc.
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Encyclopædia Britannica, Inc.An overview of the role greenhouse gases play in modifying Earth's climate.
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Encyclopædia Britannica, Inc.Flowers attract pollinators such as bees.
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Created and produced by QA International. © QA International, 2010. All rights reserved. www.qa-international.comLiving organisms influence the cycling of carbon and oxygen through the environment.
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Encyclopædia Britannica, Inc.An overview of the nitrogen and phosphorus cycles in the biosphere.
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Contunico © ZDF Studios GmbH, Mainz; Thumbnail © Mangroove/Dreamstime.comLearn about researchers studying melting permafrost on mountains in order to predict and protect against avalanches.
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Encyclopædia Britannica, Inc.Ferns, like all tracheophytes, have vascular systems to bring water up to their leaves.
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Encyclopædia Britannica, Inc.Scientists believe that human activity is causing Earth's air to become warmer through the production and release of carbon dioxide, methane, and other greenhouse gases.
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Contunico © ZDF Studios GmbH, Mainz; Thumbnail © Dmitry Pichugin/Dreamstime.comLearn about the impact of climate change on the Southern Alps/Kā Tiritiri o te Moana, South Island, New Zealand.
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Encyclopædia Britannica, Inc.Evidence of Earth's glacial past.
Transcript
NARRATOR: How do industry, agriculture, and forestry affect weather and climate on the Earth?
Today people worry whether the atmosphere has too much carbon dioxide. They actively release carbon dioxide into the air by burning fossil fuels. Plants remove carbon dioxide from the air as they grow and give off oxygen as a by-product of photosynthesis. Photosynthetic plankton in the sea do the same. But as forests are harvested and oceans become polluted, the plants and plankton--as well as their ability to restore the air--are removed from the ecosystem, and the balance of the air's chemistry may change.
As the concentration of carbon dioxide increases in the air, Earth's natural greenhouse effect is enhanced. Most gases in the air do not slow the emission of heat back into space from the Earth. However, carbon dioxide in the air holds some of this heat near Earth's surface. Thus, as carbon dioxide increases in the atmosphere, its ability to retain heat also increases, so air near Earth's surface becomes warmer.
Most scientists fear that increases in carbon dioxide concentrations have been responsible for increases in global average temperatures. Analyses of climate data show that some formerly stable glaciers and ice shelves have begun to melt away. As this water runs off the land, it enters the oceans, causing sea levels to rise, and cities located along coastlines are put at greater risk of flooding.
A warmer atmosphere may also bring about changes in wind and rainfall. Such changes can affect crop production: some areas may receive too much rainfall, while others may receive not enough. Some historically productive growing areas are expected to decline while new areas formerly unsuited for agriculture might become productive. The chain of consequences that result from modified climate and agriculture may alter Earth's economy and politics.
Today people worry whether the atmosphere has too much carbon dioxide. They actively release carbon dioxide into the air by burning fossil fuels. Plants remove carbon dioxide from the air as they grow and give off oxygen as a by-product of photosynthesis. Photosynthetic plankton in the sea do the same. But as forests are harvested and oceans become polluted, the plants and plankton--as well as their ability to restore the air--are removed from the ecosystem, and the balance of the air's chemistry may change.
As the concentration of carbon dioxide increases in the air, Earth's natural greenhouse effect is enhanced. Most gases in the air do not slow the emission of heat back into space from the Earth. However, carbon dioxide in the air holds some of this heat near Earth's surface. Thus, as carbon dioxide increases in the atmosphere, its ability to retain heat also increases, so air near Earth's surface becomes warmer.
Most scientists fear that increases in carbon dioxide concentrations have been responsible for increases in global average temperatures. Analyses of climate data show that some formerly stable glaciers and ice shelves have begun to melt away. As this water runs off the land, it enters the oceans, causing sea levels to rise, and cities located along coastlines are put at greater risk of flooding.
A warmer atmosphere may also bring about changes in wind and rainfall. Such changes can affect crop production: some areas may receive too much rainfall, while others may receive not enough. Some historically productive growing areas are expected to decline while new areas formerly unsuited for agriculture might become productive. The chain of consequences that result from modified climate and agriculture may alter Earth's economy and politics.