page_title: Clathrate gun hypothesis
section_title: Arctic Ocean
hierarchical_section_title: Clathrate gun hypothesis / Current outlook / Arctic Ocean
caption_attribution_description: The permafrost of the East Siberian Arctic Shelf (an area of about 2 million kilometers squared) is more porous than previously thought. The ocean on top of it and the heat from the mantle below it warm it and make it perforated like Swiss cheese. This allows methane gas stored under it under pressure to burst into the atmosphere. The amount leaking from this locale is comparable to all the methane from the rest of the world's oceans put together. Methane is a greenhouse gas more than 30 times more potent than carbon dioxide. Credit: Zina Deretsky, National Science Foundation For more about this research, see www.nsf.gov/news/news_summ.jsp?cntn_id=116532. Visit NSF’s Multimedia Gallery, at www.nsf.gov/news/mmg, for more images, and for video.
context_page_description: The clathrate gun hypothesis refers to a proposed explanation for the periods of rapid warming during the Quaternary. The idea is that changes in fluxes in upper intermediate waters in the ocean caused temperature fluctuations that alternately accumulated and occasionally released methane clathrate on upper continental slopes, these events would have caused the Bond Cycles and individual interstadial events, such as the Dansgaard–Oeschger interstadials.
  The hypothesis was supported for the Bølling-Allerød and Preboreal period, but not for Dansgaard–Oeschger interstadials, although there are still debates on the topic.
context_section_description: Research carried out in 2008 in the Siberian Arctic showed millions of tons of methane being released, apparently through perforations in the seabed permafrost, with concentrations in some regions reaching up to 100 times normal levels. The excess methane has been detected in localized hotspots in the outfall of the Lena River and the border between the Laptev Sea and the East Siberian Sea. At the time, some of the melting was thought to be the result of geological heating, but more thawing was believed to be due to the greatly increased volumes of meltwater being discharged from the Siberian rivers flowing north. The current methane release had previously been estimated at 0.5 megatonnes per year. Shakhova et al. (2008) estimate that not less than 1,400 gigatonnes of carbon is presently locked up as methane and methane hydrates under the Arctic submarine permafrost, and 5–10% of that area is subject to puncturing by open taliks. They conclude that "release of up to 50 gigatonnes of predicted amount of hydrate storage [is] highly possible for abrupt release at any time".  That would increase the methane content of the planet's atmosphere by a factor of twelve, equivalent in greenhouse effect to a doubling in the current level of CO
  2.
  This is what led to the original Clathrate gun hypothesis, and in 2008 the United States Department of Energy National Laboratory system and the United States Geological Survey's Climate Change Science Program both identified potential clathrate destabilization in the Arctic as one of four most serious scenarios for abrupt climate change, which have been singled out for priority research. The USCCSP released a report in late December 2008 estimating the gravity of this risk. A 2012 assessment of the literature identifies methane hydrates on the Shelf of East Arctic Seas as a potential trigger.
  Hong et al. 2017 studied methane seepage in the shallow arctic seas at the Barents Sea close to Svalbard. Temperature at the seabed has fluctuated seasonally over the last century, between -1.8 and 4.8 °C, it has only affected release of methane to a depth of about 1.6 meters at the sediment-water interface. Hydrates can be stable through the top 60 meters of the sediments and the current observed releases originate from deeper below the sea floor. They conclude that the increased methane flux started hundreds to thousands of years ago, noted about it, "..episodic ventilation of deep reservoirs rather than warming-induced gas hydrate dissociation." Summarizing his research, Hong stated:
  The results of our study indicate that the immense seeping found in this area is a result of natural state of the system. Understanding how methane interacts with other important geological, chemical and biological processes in the Earth system is essential and should be the emphasis of our scientific community.
caption: Potential Methane release in the Eastern Siberian Arctic Shelf
exif: {}