Ice Caps Are Melting Even in Winter, Global Warming Evidence Mounts

By Jane Kay
The San Francisco Chronicle

Wednesday 13 September 2006

Greenbelt, Maryland - The vast expanses of ice floating in the Arctic Sea are shrinking in winter as well as summer, most likely a result of global warming, NASA scientists said today.

"This is the strongest evidence yet of global warming in the Arctic," said Josefino Comiso, a research scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.

If the ice caps continue to melt, Comiso said, it could have very profound effects on the polar bear and other marine mammals living in the Arctic.

A greater number of polar bears have been showing up in Eskimo communities in the Arctic, apparently searching for food, scientists said today. They usually hunt for seals and other marine mammals out on the sea ice, and fast when they are on land.

Ian Stirling, a biologist in the Canadian Wildlife Service, and NASA scientist Claire Parkinson released results of their new study that shows that just because there are more sightings doesn't mean that there are more polar bears.

The new data show that both winter and summer ice is melting faster than measured in the last 26 years.

NASA has measured sea ice since 1978, compiling an average of wintertime melt. In the last two winters - 2005 and 2006 - an extra 6 percent has melted.

The summer Arctic sea ice, for the past four years in a row, also has melted far more than average, based on satellite data. If the summer ice continues to melt at that rate, they said, the Arctic could be ice-free in the summer by the end of the century.

Until 2005, the wintertime sea ice has been relatively stable. The winter ice is permanent, a thick multilayered cap that remains fairly constant. In contrast, in the summer, the ice is thinner, more mobile and melts at the edges every spring and freezes up again in the autumn.

When Comiso saw the decline of winter sea ice in 2005, he said, "it was only one year, and I didn't think it was so serious."

But these past two years were low, he said, and based on NASA data and his computer simulations, "this has a very large chance of continuing."