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Methane (CH 4) concentrations in the atmosphere measured by the Advanced Global Atmospheric Gases Experiment (AGAGE) in the lower atmosphere (troposphere) at stations around the world. Values are given as pollution free monthly mean mole fractions in parts-per-billion. [1] Atmospheric methane is the methane present in Earth's atmosphere. [2]
Methane clathrate (CH 4 ·5.75H 2 O) or (4CH 4 ·23H 2 O), also called methane hydrate, hydromethane, methane ice, fire ice, natural gas hydrate, or gas hydrate, is a solid clathrate compound (more specifically, a clathrate hydrate) in which a large amount of methane is trapped within a crystal structure of water, forming a solid similar to ice.
Large stores of methane can be found in the form of methane ice under permafrost and on continental shelves. Additional methane is produced by the anaerobic decay of organic material and is produced in organisms' digestive tracts, soil, etc. Natural methane production accounts 10-30% of global methane sources. [12]
Methane traps about 28 times the heat per molecule as carbon dioxide but lasts a decade or so in the atmosphere instead of centuries or thousands of years like carbon dioxide, according to the U.S ...
One of the researchers noted, "The expectation is that with further sea ice decline, temperatures in the Arctic will continue to rise, and so will methane emissions from northern wetlands." [50] Cracks in Arctic sea ice expose the seawater to the air, causing mercury in the air to be absorbed into the water.
Methane's GWP 20 of 85 means that a ton of CH 4 emitted into the atmosphere creates approximately 85 times the atmospheric warming as a ton of CO 2 over a period of 20 years. [23] On a 100-year timescale, methane's GWP 100 is in the range of 28–34. Methane emissions are important as reducing them can buy time to tackle carbon emissions. [24] [25]
Methane has a limited atmospheric lifetime, about 10 years, due to substantial methane sinks. The primary methane sink is atmospheric oxidation, from hydroxyl radicals (~90% of the total sink) and chlorine radicals (0-5% of the total sink). The rest is consumed by methanotrophs and other methane-oxidizing bacteria and archaea in soils (~5%). [7]
Deglaciation is the transition from full glacial conditions during ice ages, to warm interglacials, characterized by global warming and sea level rise due to change in continental ice volume. [1] Thus, it refers to the retreat of a glacier , an ice sheet or frozen surface layer, and the resulting exposure of the Earth 's surface.