Wednesday, April 23, 2008

NEW ARCTIC SEA ICE MELTING FASTER DURING SUMMER

PETER CALAMAI, TORONTO STAR New Arctic sea ice is now so perilously thin on average that it melts under the sunshine of clear summer skies it once could survive, American researchers conclude in a study . . . "When we had similar weather patterns in the past, they didn't appear to have as strong an effect on sea ice," said Jennifer Kay, an atmospheric scientist who led the U.S. research team. "Now because the ice is thinner you can have a chain reaction of runaway melting with a reduction in cloud cover," she said.

Research has linked the thinning of Arctic ice to warmer average temperatures caused by rising levels of greenhouse gases from human activities. Readings from U.S. submarines indicate a widespread reduction in sea ice thickness of 40 per cent since 1960.

The melting is also increased because the darker surface of open water absorbs the sun's rays as heat rather than reflecting them back into space like ice and snow.

The discovery of this additional vulnerability significantly ratchets up the prospects of international shipping within a decade through the fragile Canadian Arctic archipelago for months every year. . .

First-year ice makes up the bulk of the floating Arctic sea ice. But last summer only 13 per cent of this first-year ice survived the summer melt, instead of the customary 30 per cent. The 4.1 million kilometres of old ice remaining by September was the lowest since accurate satellite measurements began in 1979.