The Big Arctic Thaw
The fast melting Arctic sea ice will cause inland temperatures to rise, according to a new study, releasing more greenhouse gases in Alaska, Canada and Russia, and more severely affecting the ecosystems
The Arctic sea ice shrank to 30 percent below its annual retreat levels and another record melt is forecast for 2008.
Siberians call this a “drunken forest.” Permafrost (long-frozen soil) in its natural state holds the trees upright. If permafrost melts, as in the photo, the soil becomes loose and can no longer provide a solid foundation for the trees, which tip over and lean randomly. NASA Photo. Kochechum River, Evenkiyskiy Avtonomnyy Okrug, Russia; 66°20’N 99°00’E
As we traveled down river, I saw what the Siberians call a “drunken forest”. This area is permafrost, where the soil stays firmly frozen year round. Larch grows well here, but their roots are shallow. When permafrost melts, the trees lose their footing and tilt to the side. I guess the trees look like a drunk trying to walk home, tilted at crazy angles. It is a curious sight, but it is also a clear sign that the temperature in that spot has been warm enough to melt the permafrost. — Weblog of Dr. Jon Ranson in Siberia.
“Our climate model suggests that rapid ice loss is not necessarily a surprise,” said David Lawrence of the National Center for Atmospheric Research, one of the study authors.
“When you get certain conditions in the Arctic—thin ice, a lot of first-year ice (as opposed to older, sturdier ice)—that you can get a situation where … you get a rapid and steady loss over a period of five to 10 years,” Lawrence said.
In a period of rapid ice loss, autumn temperatures on the Arctic coasts of Alaska, Canada and Russia could rise by about 5 °C, the study’s climate model revealed.
Last year’s temperatures from August to October over land in the western Arctic were In the unusually warm autumn of 2007 the western Arctic temperatures rose by about 2 °C above the average recorded temperatures for the previous 28 years. As the sea ice melted rapidly, the scientists discovered, Arctic land warmed three and a half times faster than the rate predicted by most climate models. Simulations show that the warmer ocean temperatures can affect inland areas as far as 1,500km away.
Where permafrost is already at risk, for example, in central Alaska, warmer ocean temperatures are causing a quicker permafrost thaw. Thawed clumps of permafrost soil are already collapsing in parts of Alaska causing highways to buckle, houses to tilt and trees to tip over at random angles [a phenomenon which Siberians call "drunken forests."]
“There’s an interconnectedness about the Arctic,” Lawrence said. “When sea ice retreats and retreats very rapidly it impacts other parts of the system, like warming temperatures over land. And warming temperatures over land can also accelerate the degradation of permafrost, particularly permafrost that’s warm right now.”
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