Wednesday, 15 April 2009

Arctic Ice Got Smaller, Thinner, Younger This Winter

Arctic Ice Got Smaller, Thinner, Younger This Winter

Brian Handwerk
for National Geographic News
April 6, 2009

Turns out there is such a thing as being too young and too thin.


Arctic ice continued its decline this winter, with hardy, thicker old ice increasingly being replaced with quick-to-melt, thinner young ice, according to a new report by NASA and the National Snow and Ice Data Center.

This winter's maximum Arctic sea ice extent was 5.85 million square miles (15,150,000 square kilometers)—about 278,000 square miles (720,000 square kilometers) less than the Arctic average between 1979 and 2000.

"That's a loss about the size of the state of Texas," said Walter Meier of the National Snow and Ice Data Center (NSIDC) in Boulder, Colorado.

"We used to have a winter ice maximum about twice the size of the lower 48 United States," Meier added.

This year's ice cover was not a record low, but it did continue a dubious streak. The past six years (2004-09) have seen the least Arctic ice at the time of maximum cover, in winter, since satellite records began in 1979.

Young and Thin

Ice a year or more old—thicker, hardier, and less prone to melting than younger ice—was at an all-time low at the end of this past winter, the new report says.

Ice older than two years once accounted for some 30 to 40 percent of the Arctic's wintertime cover and made up 25 percent as recently as 2007.

But last year it represented only 14 percent of the maximum. This year the figure fell to 10 percent.

The team did report one ray of hope. In winter 2008-09, more new ice (in this case from winter 2007-08) had survived the summer than in years past.

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