Arctic methane release is the release of methane from seas and soils in permafrost regions of the Arctic. While a long-term natural process, it may be exacerbated by global warming. This results in a positive feedback effect, as methane is itself a powerful greenhouse gas. The feedback of the undisturbed process is comparably weak, however, because the local release leads to a warming spread over the whole globe.
The Arctic region is one of the many natural sources of the greenhouse gas methane. Global warming accelerates its release, due to both release of methane from existing stores, and from methanogenesis in rotting biomass. Large quantities of methane are stored in the Arctic in natural gas deposits, permafrost, and as submarine clathrates. Permafrost and clathrates degrade on warming, thus large releases of methane from these sources may arise as a result of global warming. Other sources of methane include submarinetaliks, river transport, ice complex retreat, submarine permafrost and decaying gas hydrate deposits.
During interglacials, average atmospheric methane concentrations are nearly twice the lowest values in the depths of glacial. Concentrations in the Arctic atmosphere are higher by 8–10% than that in the Antarctic atmosphere. During cold glacier epochs, this gradient decreases to practically insignificant levels. Land ecosystems are considered the main sources of this asymmetry, although it has been suggested that “the role of the Arctic Ocean is significantly underestimated. Soil temperature and moisture levels have been found to be significant variables in soil methane fluxes in tundra environments.
According to an article in Science, while methane release is indeed likely to amplify global warming to an unknown level, fears that it could lead to catastrophe are possibly overblown.
National Science Foundation Magazine
Methane Releases From Arctic Shelf May Be Much Larger and Faster Than Anticipated
Thawing by climate change of subsea layer of permafrost may release stores of underlying, seabed methane…
March 4, 2010
A section of the Arctic Ocean seafloor that holds vast stores of frozen methane is showing signs of instability and widespread venting of the powerful greenhouse gas, according to the findings of an international research team led by University of Alaska Fairbanks scientists Natalia Shakhova and Igor Semiletov.
The research results, published in the March 5 edition of the journal Science, show that the permafrost under the East Siberian Arctic Shelf, long thought to be an impermeable barrier sealing in methane, is perforated and is starting to leak large amounts of methane into the atmosphere. Release of even a fraction of the methane stored in the shelf could trigger abrupt climate warming.
“The amount of methane currently coming out of the East Siberian Arctic Shelf is comparable to the amount coming out of the entire world’s oceans,” said Shakhova, a researcher at UAF’s International Arctic Research Center. “Subsea permafrost is losing its ability to be an impermeable cap.”http://www.nsf.gov/news/news_summ.jsp?cntn_id=116532