Polar bears may survive global warming after allS

Many have mourned the plight of polar bears, whose habitat is literally melting away as the ice caps shrink. But several new predictions from geophysicists show that the bears may be frolicking on huge regions of ice for centuries.

Nature News reports from this week's Geophysical Union meeting in San Francisco:

Stephanie Pfirman, an environmental scientist at the Lamont-Doherty Earth Observatory in New York, and her colleagues are to present climate models at the meeting tomorrow that predict sea ice will continue to pile up on the northern side of the Canadian Arctic Archipelago and Greenland, where the thickest sea ice exists today. Some of this ice is formed locally, and some is driven in from Siberia by wind and ocean currents. Pfirman estimates that an area of ice perhaps half a million square kilometres in size is likely to persist year-round long into the twenty-first century.

Although the amount of ice that melts each summer is increasing, ice is still forming in the winter, and it is being transported to the Canadian side of the Arctic faster than before because the waters are more open. "If it used to take 8 or 9 years to make the trip, it might now do it in 7 years," says Robert Newton, a geochemist also at Lamont-Doherty.

A paper published in Nature today brings more good news for Arctic ice. Steven Amstrup of the US Geological Survey in Anchorage, Alaska, and his colleagues looked at models of future sea ice circulation and found no evidence of a 'tipping point' of warming beyond which the ice will disappear irreversibly. So bringing greenhouse-gas emissions under control, they write, should help to preserve polar-bear habitat and Arctic ecosystems at large.

Read more about how polar bears may survive the next century in Nature News.

Photo by Douglas C. Pizac/AP