arcticicelevelsatrecordlow

According to data from NASA's QuikSCAT satellite, between 2004 and 2005 the Arctic lost an unprecedented 14 percent of its perennial sea ice 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 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

Arctic Ice Levels at Record Low May Keep Melting, Study Warns

The amount of sea ice in the Arctic shrank dramatically this summer and is now smaller than it has been in a century of record-keeping, new research reveals.

Scientists say rising temperatures brought on by human-made global warming is probably to blame for the melting

If the decline in sea ice continues, summers in the Arctic could become completely ice-free before the end of this century, scientists warn.

The shift could lead to increased coastal erosion and shrinking habitat for animals like polar bears.

"We're going to see a dramatically different Arctic," said Mark Serreze, a research scientist at the National Snow and Ice Data Center in Boulder, Colorado. The center led the research, which also involved NASA, the National Oceanic and Atmospheric Administration, and the University of Washington.

Record-Low Levels

Since 2002 satellite imagery has revealed strong melting north of Siberia and Alaska in the early springtime. According to the new research, however, the melting trend has now spread throughout the Arctic.

"In 2002 we were already flabbergasted at how little ice we had, but in the past four years the bottom has kind of dropped out of the system," Serreze said. "The difference in ice cover from 2002 to 2005 is roughly the size of Colorado."

Arctic sea ice builds up in the winter and melts in the summer, typically reaching its minimum in September. On September 21, the sea ice extent—or the area of ocean that is covered by at least 15 percent ice—had dropped to 2 million square miles (5.3 million square kilometers), the lowest ever observed during the satellite record, which dates back to 1978.

There are natural causes that may lead to the increased melting. Scientists believe that a circulation pattern in the atmosphere that pushes sea ice out of the Arctic region may have contributed to periodic ice reduction in the past.

But this pattern has not been an influence on the region since 1996, researchers say, and sea-ice decline has still continued to accelerate.

"The most fundamental thing that helps explain the loss of ice is that the Arctic is simply getting warmer," Serreze said.

~ Stefan Lovgren