Where are 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, India, the continental shelf off Japan, Nigeria, the South China Sea, Norway, Peru, and Australia. Most promising for the US are Alaska’s North Slope, Blake’s Ridge, and the Gulf of Mexico.”
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 been discovered methane gas venting from methane hydrate below the East Siberian Arctic shelf.