Greenhouse gases:Methane: Greenhouse Gas Enemy Number Two
Geographical distribution of average annual methane emissions (g CH4 m–2 s–1) from northern and southern wetlands, rice fields, biomass burning, animals and their waste, or natural gas and coal energy production. Notice that the scale is logarithmic. From
Published: December 16, 2010, 12:00 am
Updated: August 21, 2012, 4:08 pm
This article has been reviewed by the following Topic Editor:
David Hassenzahl PhD
Methane (CH4) is second only to carbon dioxide (CO2) in its contribution to the greenhouse effect and accounts for about 15% of anthropogenic warming. [1] Moreover, sudden release of CH4 from the melting of seabed methane hydrate is implicated in such cataclysmic events as the Great Dying and the Late Paleocene Thermal Maximum. Once in the atmosphere, CH4 oxidizes to CO2 in about a dozen years.
Contrary to popular belief, the majority of humans do not release CH4 when they pass flatus gas [2] — this provides yet another reason why attempts to ignite these emissions are seldom worthwhile. Other human activities, however, do emit large amounts of CH4. Over 75% of the world’s rice is grown in flooded paddies. Soils during flooding soon become anaerobic, and soil microbes generate CH4, or “marsh gas,” through anaerobic respiration. Clearing of agricultural land through burning also produces CH4 because of incomplete combustion. Animals, particularly ruminants such as cows, sheep, and goats, have bacteria in their digestive tracts that generate CH4. A primary component of natural gas is CH4, and losses of CH4 occur during natural gas extraction, processing, storage, transmission, and distribution. Coal deposits also contain trapped CH4 that is released during normal mining operations in both underground and surface mines.
All together, the human activities of agriculture, biomass burning, and energy production release somewhere around 320 gigatons (Gt) of CH4 per year. [3] These sources, together with CH4 produced by natural wetlands and non-domestic animals such as wild ruminants and termites, emit a total of between 410 and 660 Gt CH4 per year. [4] Various scenarios about future demographic, social, economic, technological, and environmental conditions predict that global CH4 emissions will be between 500 and 1150 Gt CH4 y-1 by the end of the century and that atmospheric concentrations will reach between 1.4 and 3.6 parts per million (ppm).
This is an excerpt from the book Global Climate Change: Convergence of Disciplines by Dr. Arnold J. Bloom and taken from UCVerse of the University of California.
©2010 Sinauer Associates and UC Regents
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Citation
Arnold J Bloom (Lead Author);David Hassenzahl PhD (Topic Editor) "Methane: Greenhouse Gas Enemy Number Two". In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth December 16, 2010; Last revised Date August 21, 2012; Retrieved May 24, 2013 <http://www.eoearth.org/article/Methane:_Greenhouse_Gas_Enemy_Number_Two?topic=60586>
The Author
Arnold J. Bloom became a botanist through a circuitous route. Upon receiving an undergraduate degree in Physics from Yale University, he spent several years developing computer models of the spread of air pollution over cities in the USA and Germany. He received a Ph.D. in Biological Sciences from Stanford University, where he also completed a two-semester course in Environmental Legislation at the Law School. He conducted postdoctoral research on the temperature responses of plants at the ... (Full Bio)
Methane (CH4) is second only to carbon dioxide (CO2) in its contribution to the greenhouse effect and accounts for about 15% of anthropogenic warming. [1] Moreover, sudden release of CH4 from the melting of seabed methane hydrate is implicated in such cataclysmic events as the Great Dying and the Late Paleocene Thermal Maximum. Once in the atmosphere, CH4 oxidizes to CO2 in about a dozen years.
Contrary to popular belief, the majority of humans do not release CH4 when they pass flatus gas [2] — this provides yet another reason why attempts to ignite these emissions are seldom worthwhile. Other human activities, however, do emit large amounts of CH4. Over 75% of the world’s rice is grown in flooded paddies. Soils during flooding soon become anaerobic, and soil microbes generate CH4, or “marsh gas,” through anaerobic respiration. Clearing of agricultural land through burning also produces CH4 because of incomplete combustion. Animals, particularly ruminants such as cows, sheep, and goats, have bacteria in their digestive tracts that generate CH4. A primary component of natural gas is CH4, and losses of CH4 occur during natural gas extraction, processing, storage, transmission, and distribution. Coal deposits also contain trapped CH4 that is released during normal mining operations in both underground and surface mines.
All together, the human activities of agriculture, biomass burning, and energy production release somewhere around 320 gigatons (Gt) of CH4 per year. [3] These sources, together with CH4 produced by natural wetlands and non-domestic animals such as wild ruminants and termites, emit a total of between 410 and 660 Gt CH4 per year. [4] Various scenarios about future demographic, social, economic, technological, and environmental conditions predict that global CH4 emissions will be between 500 and 1150 Gt CH4 y-1 by the end of the century and that atmospheric concentrations will reach between 1.4 and 3.6 parts per million (ppm).
This is an excerpt from the book Global Climate Change: Convergence of Disciplines by Dr. Arnold J. Bloom and taken from UCVerse of the University of California.
©2010 Sinauer Associates and UC Regents
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