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Although individual CO 2 molecules have a short residence time in the atmosphere, it takes an extremely long time for carbon dioxide levels to sink after sudden rises, due to e.g. volcanic eruptions or human activity [17] and among the many long-lasting greenhouse gases, it is the most important because it makes up the largest fraction of the ...
This is an accepted version of this page This is the latest accepted revision, reviewed on 24 January 2025. Gas in an atmosphere with certain absorption characteristics This article is about the physical properties of greenhouse gases. For how human activities are adding to greenhouse gases, see Greenhouse gas emissions. Greenhouse gases trap some of the heat that results when sunlight heats ...
In this expression σ is the Stefan–Boltzmann constant and ε represents the emissivity of the atmosphere, which is less than 1 because the atmosphere does not emit within the wavelength range known as the atmospheric window. Aerosols, clouds, water vapor, and trace greenhouse gases contribute to an effective value of about ε = 0.78.
The rise in CO 2 over that time period is clearly visible. The concentration is expressed as μmole per mole, or ppm. In Earth's atmosphere, carbon dioxide is a trace gas that plays an integral part in the greenhouse effect, carbon cycle, photosynthesis and oceanic carbon cycle. It is one of three main greenhouse gases in the atmosphere of Earth.
Both of these gases absorb and retain heat in the atmosphere and are partially responsible for the greenhouse effect. [7] Methane produces a larger greenhouse effect per volume as compared to carbon dioxide, but it exists in much lower concentrations and is more short-lived than carbon dioxide.
Greenhouse gases make the atmosphere near Earth's surface mostly opaque to longwave radiation. The atmosphere only becomes transparent to longwave radiation at higher altitudes, where the air is less dense, there is less water vapor, and reduced pressure broadening of absorption lines limits the wavelengths that gas molecules can absorb. [56] [46]
4, which is a powerful greenhouse gas and was produced by early forms of life known as methanogens. Scientists continue to research how the Earth was warmed before life arose. [14] An atmosphere of N 2 and CO 2 with trace amounts of H 2 O, CH 4, carbon monoxide (CO), and hydrogen (H 2) is described as a weakly reducing atmosphere. [15]
Methane (CH 4) in the Earth's atmosphere is a powerful greenhouse gas with a global warming potential (GWP) 84 times greater than CO 2 over a 20-year time frame. [22] [23] Methane is not as persistent as CO 2, and tails off to about 28 times greater than CO 2 over a 100-year time frame. [10]