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Arctic ice in "Death Spiral," near record low

By Mason Inman | National Geographic

Sea ice covering the Arctic Ocean (taken in a satellite image on 9 September 2008) shrank to the second smallest size on record in the summer of 2008 and may disappear in the summer within a couple of decades, new data shows.NASA/Goddard

The ice is in a “death spiral” and may disappear in the summers within a couple of decades, according to Mark Serreze, an Arctic climate expert at the National Snow and Ice Data Center in Boulder, Colorado.

Each winter, sea ice fills most of the Arctic Ocean. The ice pack then melts and shrinks in the summer heat.

With additional heating due to global warming, the extent of sea ice cover has gotten smaller and smaller over the summers since the 1980s.

This has scientists concerned—and not just because the ice melt is a symptom of global warming. Sea ice has a cooling effect by reflecting sunlight back into space. So when the ice shrinks and opens up more ocean, more of the sun’s heat is soaked up by the dark sea.

This heats up the Arctic — and the planet — more than the greenhouse effect on its own, in turn melting even more ice.

“With the climate feedbacks kicking in,” Serreze said by email, “we’ll lose the summer ice cover probably by the year 2030.”

Extraordinary melt

The 2007 melt last year smashed a previous record set in 2005.

But 2007 saw special conditions that favored melting, researchers say. “The most important factor in 2007,” Serreze said, “was an unusual pattern of atmospheric circulation in summer that brought warm, southerly winds north of eastern Siberia, promoting strong melt.”

Copyright © 2008 National Geographic Society

Published in National Geographic News