Dramatic Thermal Changes and Increased Methane

Origin of pingo-like features on the Beaufort Sea shelf and their possible relationship to decomposing methane gas hydrates

Abstract

The Arctic shelf is currently undergoing dramatic thermal changes caused by the continued warming associated with Holocene sea level rise. During this transgression, comparatively warm waters have flooded over cold permafrost areas of the Arctic Shelf. A thermal pulse of more than 10°C is still propagating down into the submerged sediment and may be decomposing gas hydrate as well as permafrost. A search for gas venting on the Arctic seafloor focused on pingo-like-features (PLFs) on the Beaufort Sea Shelf because they may be a direct consequence of gas hydrate decomposition at depth. Vibracores collected from eight PLFs had systematically elevated methane concentrations. ROV observations revealed streams of methane-rich gas bubbles coming from the crests of PLFs. We offer a scenario of how PLFs may be growing offshore as a result of gas pressure associated with gas hydrate decomposition.

http://www.agu.org/pubs/crossref/2007/2006GL027977.shtml

Received 23 August 2006; accepted 20 November 2006; published 5 January 2007.

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