Thursday, September 14, 2006

Photo in the news: Arctic ice melting rapidly, study shows


The rate of ice loss in the Arctic is accelerating rapidly, scientists say.

According to data from NASA's QuikSCAT satellite, between 2004 and 2005 the Arctic lost an unprecedented 14 percent of its perennial sea ice (shown in white)�some 280,000 square miles (725,000 square kilometers), or an area the size of Texas.

Perennial ice remains year-round and has a thickness of ten feet (three meters) or more. That ice was replaced with seasonal ice 1 to 7 feet (0.3 to 2.1 meters) thick (shown in pink), which is much more vulnerable to melting in the summer.

Since the 1970s summer ice in the Arctic has reduced at a rate of 6.4 to 7.8 percent per decade, the researchers write in the September 7 issue of the journal Geophysical Research Letters. This suggests ice loss may now be occurring up to 18 times more quickly.

(Related: "Arctic Ice Levels at Record Low, May Keep Melting, Study Warns" [October 2005].)

Ice wasn't lost from all areas equally. The east Arctic Ocean lost 50 percent of its perennial ice. Much of the ice was pushed by winds and other factors into the western part of the ocean, where the perennial ice sheet actually grew.

But global warming probably played a significant role as well, and additional ice loss could trigger a feedback loop that would further accelerate the melting process, scientists say.

"If the seasonal ice in the east Arctic Ocean were to be removed by summer melt, a vast ice-free area would open up," research leader Son Nghiem of NASA's Jet Propulsion Laboratory in Pasadena, California, said in a press statement. "Such an ice-free area would have profound impacts on the environment, as well as on marine transportation and commerce."

The scientists report that the eastern Arctic's perennial ice sheet was reduced a further 70 percent between October 2005 and April 2006.

-- Aalok Mehta

No comments: