Could Permafrost Be More Perma Than Some Studies Project? Canadian Sample Survived 700K Years - AFP

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Ice unearthed in Canada that stayed frozen for 700,000 years, even in warmer times, should allay fears of melting permafrost venting its vast carbon stores to hasten global warming, a study said Friday. Permafrost, or subsoil that remains frozen year-round, underlies a quarter of the land in the Northern Hemisphere and is estimated to hold twice as much carbon as is in the atmosphere. When it melts, some experts fear it will quicken the pace of global warming significantly.

But the discovery of a cone-shaped wedge of subterranean ice near Dawson City, Yukon, that did not melt during balmier times shows that permafrost is more "stubborn" than first believed, researcher Duane Froese of the University of Alberta's earth and atmospheric science department told AFP. And so, current climate models that predict "extensive and severe degradation of permafrost in response to global warming, with a potential for release of large volumes of stored carbon" should be revised, the study says.

In theory, the permafrost in the interior of Yukon and Alaska, along with this wedge of ice exposed by Klondike gold mining, should have melted during more temperate periods, Froese explained. Some 120,000 years ago, for example, the Earth is believed to have been a few degrees warmer than now, he said.

The fact that the wedge did not melt indicates "some inherent properties of permafrost" are keeping it cool, and so climate models that predict significant melting of permafrost in the coming decades are wrong, he said.

EDIT

http://www.terradaily.com/reports/Cool_discovery_lifts_global_warming_outlook_researcher_999.html