Greenhouse gas - Wikipedia, the free encyclopedia

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** Greenhouse gas **

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refer to caption and image description
Greenhouse effect schematic showing energy flows between space, the
atmosphere, and Earth's surface. Energy exchanges are expressed in watts
per square meter (W/m^2).

A *greenhouse gas* (sometimes abbreviated *GHG*) is a gas in an atmosphere
that absorbs and emits radiation within the thermal infrared range. This
process is the fundamental cause of the greenhouse effect.^[1] The primary
greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide,
methane, nitrous oxide, and ozone. In the Solar System, the atmospheres of
Venus, Mars, and Titan also contain gases that cause greenhouse effects.
Greenhouse gases greatly affect the temperature of the Earth; without them,
Earth's surface would average about 33°C colder than the present average
of 14 °C (57 Â°F).^[2]^[3]^[4]

Since the beginning of the Industrial Revolution, the burning of fossil
fuels has contributed to a 40% increase in the concentration of carbon
dioxide in the atmosphere from 280 ppm to 400 ppm,^[5] despite the uptake
of a large portion of the emissions by various natural "sinks" involved in
the carbon cycle.^[6]^[7] Anthropogenic carbon dioxide (CO[2]) emissions
(i.e., emissions produced by human activities) come from combustion of
carbon based fuels, principally wood, coal, oil, and natural gas.^[8]

*Contents*

· 1 Gases in Earth's atmosphere

· 1.1 Greenhouse gases
· 1.2 Non-greenhouse gases
· 1.3 Indirect radiative effects
· 1.4 Contribution of clouds to Earth's greenhouse effect

· 2 Impacts on the overall greenhouse effect

· 2.1 Proportion of direct effects at a given moment
· 2.2 Atmospheric lifetime
· 2.3 Radiative forcing
· 2.4 Global warming potential

· 3 Natural and anthropogenic sources

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Source: en.wikipedia.org/wiki/Greenhouse_gas


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