Arctic Speed-Melt Record

| Fri Sep. 26, 2008 5:15 PM PDT

Although 2008 did not set a record for minimum sea ice it did set a record for speed melting. Arctic sea ice declined at a rate of 32,700 square miles a day in August. That's about the size of Maine. Every day. And that's compared to 24,400 square miles a day lost in August 2007—the record holder for minimum sea ice.

The 2008 results were surprising, says NASA, because last winter had near-normal ice cover. "We saw a lot of cooling in the Arctic that we believe was associated with La Niña," says Joey Comiso of NASA's Goddard Space Flight Center in Maryland. "Sea ice in Canada had recovered and even expanded in the Bering Sea and Baffin Bay. Overall, sea ice recovered to almost average levels. That was a good sign that this year might not be as bad as last year."

But alas the sprint in August—the fastest-ever melt—undid the gains of the winter. Here's what it looked like:

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"Based on what we've learned over the last 30 years, we know that the perennial ice cover is now in trouble," Comiso says. "You need more than just one winter of cooling for the ice to recover to the average extent observed since the measurements began. But the trend is going the other way. A warming Arctic causes the surface water to get warmer, which delays the onset of freeze up in the winter and leads to a shorter period of ice growth. Without the chance to thicken, sea ice becomes thinner and more vulnerable to continued melt."

Julia Whitty is Mother Jones' environmental correspondent, lecturer, and 2008 winner of the Kiriyama Prize and the John Burroughs Medal Award.

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