How long will the poles stay frozen?
By Mary Carmichae
April 2, 2007 issue – Every year, the cap of sea ice floating atop the North Pole dwindles from about 14 million to 7 million square kilometers—a number that would panic scientists if it weren’t a normal occurrence, courtesy of nature. Most of the summer shrinkage is caused by melting, and the pack ice grows again once winter arrives, freezing the choppy water back into solid sheets. Because it’s a recurring cycle, scientists have never found this phenomenon worrisome. Until this year, when Ronald Kwok of NASA’s Jet Propulsion Laboratory rang the alarm. He’d noticed that in 2005, little of the ice that had formed the previous winter had gone on to survive the summer—making the Arctic cap the smallest it had been in five decades.
The polar regions are notorious shape-shifters. Complex ecosystems, they can be swayed by factors from wind to water to warming, and their forbidding climate makes on-site research difficult. As a result, they’re a bit of a mystery to scientists, and their future is hard to predict. But with ever more omens foretelling the death of the ice caps—possibly, in some models, by the year 2040—researchers are launching a major effort to make such a prediction. Mark Serreze of the University of Colorado’s National Snow and Ice Data Center says the 2040 doomsday forecast "has gotten thrown around too loosely." We might have more time than that, he says: it could be 2060, 2070, 2080. On the other hand, it could be sooner. "We may already have had a kick to the system that has sent it over the edge," says Serreze. Either way, he adds, most researchers agree it’s a question of "when," because it’s too late for "if."
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