Decomposing methane gas hydrates on Arctic Shelf?

More than 8,000 years ago, parts of the Arctic Shelf were an unglaciated coastal plain covered with thick permafrost. As sea levels rose, this permafrost became submerged and is currently inundated by relatively warm seawater.

Permafrost is known to contain gas hydrates, a solid phase composed of water and gases that formed under low-temperature, high-pressure conditions. Because disturbances to permafrost may cause the release of methane, a potent greenhouse gas, from the hydrates, Paull et al. sought to determine whether such venting was occurring on the Arctic's submerged Beaufort Sea Shelf. They focused on underwater

features similar in shape to terrestrial pingos, which are conical, ice- cored hills. Data collected from eight pingo-like formations revealed systematically elevated methane concentrations and streams of methane-rich gas bubbles coming from the formations' crests. They hypothesize that pressure generated by methane gas hydrate decomposition within subsurface permafrost layers helped to push ice-rich sediment above the surrounding seafloor, forming pingo-like formations. They expect that after degassing, the seafloor subsides around the pingo-like formations, forming moat-like depressions that have also been observed in bathymetric surveys. - American Geophysical Union