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Wikenigma - an Encyclopedia of Unknowns Wikenigma - an Encyclopedia of the Unknown

Global Atmospheric Methane Cycle

Methane is roughly 80 times more potent as a Greenhouse Gas (GG) than CO2. Over the last 30 years, the measured levels in the atmosphere have been steadily rising, - maintaining a clearly-defined seasonal cycle.

Methane is an important greenhouse gas, responsible for about 20% of the warming induced by long-lived greenhouse gases since pre-industrial times. By reacting with hydroxyl radicals, methane reduces the oxidizing capacity of the atmosphere and generates ozone in the troposphere. Although most sources and sinks of methane have been identified, their relative contributions to atmospheric methane levels are highly uncertain."

Source : Three decades of global methane sources and sinks, Nature Geoscience, 2013

As noted above, reactions with hydroxyl radicals are foremost in 'sinks' to absorb methane - but their production is unclear.

The most important sink in the methane cycle is reaction with the hydroxyl radical, which is produced photochemically in the atmosphere. Production of this radical is not fully understood and has a large effect on atmospheric concentrations."

More info at: Wikipedia

The balance between sources and sinks of methane is not yet fully understood. The IPCC Working Group I stated in chapter 2 of the Fourth Assessment Report that there are 'large uncertainties in the current bottom-up estimates of components of the global source', and the balance between sources and sinks is not yet well known."

According to the US National Oceanic and Atmospheric Administration (NOAA) global atmospheric methane levels increased by a record amount in 2021, for the second year in a row. Source : NOAA

Note :

As far as Wikenigma has been able to determine, none of the widely used computational Climate Models currently take account of methane levels.


Also see : Methane hydratesplugin-autotooltip__plain plugin-autotooltip_bigMethane hydrates

Mehane hydrates - a.k.a. methane clathrates - are an important factor in total global methane levels (see Global Atmospheric Methane Cycle)

They are commonly found in permafrost deposits and on (and under) the sea floor, being a frozen, naturallyā€occurring, and highlyā€concentrated form of methane linked with water molecules.
and Aerobic methane productionplugin-autotooltip__plain plugin-autotooltip_bigAerobic methane production

From 2005 onwards, satellite-based observations found elevated levels of methane (CH4) in the atmosphere above evergreen forests in tropical regions.

Methane is a very potent greenhouse gas, and intense research effort went into trying to discover the source. Because methane degrades relatively rapidly* in the atmosphere, it's clear that there must be some local production mechanism.

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