Post by Mech on Feb 2, 2007 16:46:19 GMT -5
Methane is a far greater cause of warming than anything linked to humans.
GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L01603, doi:10.1029/2006GL027977, 2007
Origin of pingo-like features on the Beaufort Sea shelf and their possible relationship to decomposing methane gas hydrates
www.agu.org/pubs/crossref/2007/2006GL027977.shtml
Charles K. Paull
Monterey Bay Aquarium Research Institute, Moss Landing, California, USA
William Ussler III
Monterey Bay Aquarium Research Institute, Moss Landing, California, USA
Scott R. Dallimore
Natural Resources Canada, Sidney, British Columbia, Canada
Steve M. Blasco
Natural Resources Canada, Dartmouth, Nova Scotia, Canada
Thomas D. Lorenson
U.S. Geological Survey, Menlo Park, California, USA
Humfrey Melling
Fisheries and Oceans Canada, Sidney, British Columbia, Canada
Barbara E. Medioli
Natural Resources Canada, Ottawa, Ontario, Canada
F. Mark Nixon
Natural Resources Canada, Ottawa, Ontario, Canada
Fiona A. McLaughlin
Fisheries and Oceans Canada, Sidney, British Columbia, Canada
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.
Received 23 August 2006; accepted 20 November 2006; published 5 January 2007.
Keywords: Arctic; methane gas hydrate; gas venting.
Index Terms: 0702 Cryosphere: Permafrost (0475); 1630 Global Change: Impacts of global change (1225); 3002 Marine Geology and Geophysics: Continental shelf and slope processes (4219); 3004 Marine Geology and Geophysics: Gas and hydrate systems; 9315 Geographic Location: Arctic region (0718, 4207).