Yahoo News 14 Dec 07;
The arctic ice cap melted at an unprecedented rate in mid-2007, losing an area of ice the size of the state of Alaska, US scientists said at a conference this week.
"The average rate of loss of sea ice every summer year to year up to 2006 was equal to an area the size of West Virginia," or about 62,800 square kilometers (24,250 square miles), said Michael Steele, the senior oceanographer at the University of Washington in Seattle.
However the decrease in ice between 2006 and 2007 "was almost equivalent to the area of Alaska," or some 1.7 million kilometers (more than 663,000 square miles), Steele told AFP in a telephone interview.
"It was a huge retreat," said Steele, one of the researchers who discussed the subject at the annual American Geophysical Union (AGU) conference in San Francisco, California.
The arctic ice cap currently covers around 4.13 million square kilometers, its smallest surface in modern times, said another conference speaker, Wieslaw Maslowski, an oceanographer at the Naval Postgraduate School in Monterey, California.
The Arctic Ocean could thus be completely ice-free during the three summer months by 2013, Maslowski said at the conference.
Steele refused to make the same prediction, but did say that the Arctic Ocean has never been as hot during the summer months.
"The ocean warmed up at temperatures never seen before ... it was five degrees Celsius warmer than average," said Steele. "It's very large."
In arctic areas usually covered by ice "the temperature was maybe two or three degrees warmer than the average." And in Alaska the temperature was unusually high -- between 12 and 13 degrees Centigrade. "We never saw that before," he said.
Steele based his research on records over the past 100 years as well as measurements taken with instruments in the field. More recently he has also used data from NASA satellites.
Other scientists at the AGU conference said the Arctic Ocean's heating was self-sustained, with warmer water from the Atlantic and Pacific heading north and accelerating the melting of the ice caps.
Global warming due to greenhouse gas emissions produced by humans "is basically responsible for the ice getting thinner and thinner," said Steele.
"And when it gets thinner, the ice becomes more vulnerable to wind that can blow it away from Alaska and eastern Siberia. It's also more vulnerable to the unusual summer time melting -- if you have thick ice that melts a little bit, it's still there, (but) when it's thin it melts completely away."
"It's just a fact that the ice is going away and the ocean can absorb the sunlight," Steele said. With less ice to reflect the sunlight, the ocean absorbs the sun's heat, warms up and furthers the melting process.
"I don't know what the future holds, but most arctic scientists think that is not getting much better," he said.
