Since at least 1992 (US GS report) scientists have regarded methane hydrate as a potential huge source of fossil fuel energy and a catastrophic potential climate change danger.
"Methane hydrate seems intrinsically vulnerable on Earth; nowhere at the Earth's surface is it stable to melting and release of the methane, and it floats in water, so the only factor holding it at high pressure is the weight of the mud overlying it in coastal margin sediments. A few degrees of warming in the deep ocean can have a significant impact on the stability of the hydrate, and it is known that the temperature of the deep ocean responds to changes in surface climate, albeit with a lag of centuries to millennia. Hence, there are concerns that climate change could trigger significant methane releases from hydrates and thus could lead to strong positive carbon-climate feed back.' (Gas hydrates: entrance to a methane age or climate threat 2009).
Global warming through ocean warming will, when the sea floor is warmed up enough, destabilize methane hydrates, releasing methane gas. The feedback is shown by a 2006 global warming assessment for the German government (see chart to the right).
It is estimated that if 10% of methane stored in permafrost was released into the atmosphere, it would have an effect similar to a ten-fold increase in CO2. Abrupt warming would occur if the concentration of methane, or CO2, increased suddenly; this would in turn cause further melting of permafrost and release of even more ancient methane deposits; and therefore it would intensify global warming even further. This phenomenon is known as a "positive feedback." Even if methane accumulates at a slower pace, it will still intensify global warming by oxidizing to CO2, which is a less potent greenhouse gas but with a much longer lifetime (a mean of 100 years.
As far back as 1992 (USGS), the threat of an enormous global climate change impact from marine methane hydrates destabilized from global warming was recognized. The scenario is sea level rise with ocean warming from which it had been assumed that it will take hundreds of years for the hydrate to be affected.
Where are Arctic methane hydrate deposits situated?
Vast quantities of methane are stored in terrestrial and underwater permafrost. Methane deposits in frozen underwater sediments are found along the outer continental margins where there is ample organic matter supply (deposited over many thousands of years by rivers) and low water temperature.
Methane hydrates are known to occur both within and below permafrost in polar areas. Several areas in the Arctic show potential for having gas hydrate accumulations. Three areas are in North America and four are in Russia: (1) northern Alaska, (2) the Mackenzie Delta-Beaufort Sea region, (3) Sverdrup basin of Canada, (4) Western Siberia basin, (5) Lena-Tunguska province (Vilyuy basin), (6) Timan-Pechora basin, and (7) several sedimentary basins in northeastern Siberia and the Kamchatka area. Additionally, (8) the Svalbard archipelago (Norway) and (9) sedimentary basins under the ice cap of Greenland (Denmark) may have pressure and temperature conditions favourable to the formation of gas hydrates (US Department of Energy).
"'Promising energy inventories' of methane hydrates have been described in Alaska, Antarctica, the Canadian Arctic,
In the cold Arctic waters, methane hydrate can form under relatively lower pressure than other regions and so occurs in shallower water, making it stable but particularly vulnerable to global warming, which destabilizes the solid hydrate, releasing methane gas. It is especially vulnerable in the shallow East Siberian Arctic Shelf (ESAS), where 90% of Arctic methane hydrates are situated.
Unexpectedly, a team of Russian scientists researching Siberian methane emissions have discovered that ESAS hydrates are already venting methane to the atmosphere.
In the Arctic, methane hydrate can also occur deep below land permafrost.
ARCTIC METHANE HYDRATE
How much methane hydrate is there?
The Arctic is estimated to contain up to one third of global deposits (US D.Energy) and N Shakhova's figure is not less than 1400 Gt. where the vast majority of hydrate is situated
Methane gas has 160 x the volume of the solid hydrate containing it, and therefore methane hydrate destabilization will tend to be explosive — on a large or small scale. An MIT model has found methane hydrate vulnerable to warming because destabilization could be self propagating.
This because the methane gas occupoied 160X the volume of rhe solid hydrate and gas release would be disturbing, "This indicates that we may be greatly underestimating the methane fluxes presently occurring in the ocean and from underground into Earth's atmosphere" (Ruben Juanes, 2009 MIT energy research).
A 2010 review by Masin et al of the global threat from methane hydrate on a global basis found both marine and permafrost gas hydrate reservoirs are sensitive to environmental changes, they will be affected by global warming. Global warming prediction by the IPCC (2007) suggests that, by the year 2100, global mean surface temperature could rise by between 1.1°C and 6.4°C (best estimate 4°C) and global mean sea level could rise at least 28–79 cm, more if the melting of Antarctica and Greenland accelerates. These predictions include the warming of both the oceans and the permafrost regions, which could cause significant dissociation of gas hydrates, releasing unknown amounts of methane into the atmosphere. However this did not include the reasearch on Siberian ESS hydrates.
David Archer 2007 has estimated The potential climate impact in the coming century from
hydrate methane release is speculative but could be comparable to climate feedbacks from the terrestrial biosphere and from peat... That is a huge additional amount of methane.
Methane frozen into hydrate makes up a large reservoir of potentially volatile carbon below the sea
ﬂoor and associated with permafrost soils. In the same paper Archer observes This reservoir intuitively seems precarious, because hydrate ice ﬂoats in water, and melts at Earth surface conditions. The hydrate reservoir (global) is so large that if 10% of the methane were released to the atmosphere within a few years, it would have an impact on the Earth’s radiation budget equivalent to a factor of 10 increase in atmospheric CO2. Hydrates are releasing methane to the atmosphere today in response to anthropogenic warming, for example along the Arctic coastline of Siberia.
Methane hydrate within and below subterranean and submerged permafrost of the Arctic. It is conceivable that substantial release of CH4 from the melting of gas hydrate could inﬂuence the radiative forcing of climate. The northern coast of Siberia has been eroding for thousands of years and it is thought that this erosion has exposed hydrates to melting."Sensitivity of the carbon cycle in the Arctic to climate change.
David McGuire http://www.esajournals.org/doi/full/10.1890/08-2025.1 2009.
Release to the atmosphere of only 0.5 per cent of the methane stored within arctic shelf hydrates could cause abrupt climate change (N Shakhova).
Report Oct 2012 Methane hydrate: a volatile time bomb in the Arctic. In our most recent cruise this summer (June 2012) along the Fram Strait and Svalbard Islands we found ...that this area of the planet is emitting large amounts of methane into theatmosphere. C Duarte
2013 Russian Arctic workshop Subsea Permafrost, gas seeps and gas hydrates.
The most important questions about Arctic methane hydrate are still under research, so the topic can be confusing with differing conclusions.
14 April 2015 Deep Arctic methane source discovered supplying M hydrate