Arctic sea ice is melting faster, report says

By Andrew C. Revkin 
Published: May 1, 2007

Climate scientists may have significantly underestimated the power of global warming from human-generated heat-trapping gases to shrink the cap of sea ice floating on the Arctic Ocean, according to a new study of polar trends published online Tuesday.

The study, in Geophysical Research Letters, concluded that an open-water Arctic in the summers could be more likely in this century than had been estimated in the latest international review of climate research released in February by the United Nations Intergovernmental Panel on Climate Change.

"There are huge changes going on," said Julienne Stroeve, a lead author of the new study and a researcher at the U.S. National Snow and Ice Data Center in Boulder, Colorado.

"Just with warm waters entering the Arctic, combined with warming air temperatures, this is wreaking havoc on the sea ice."

The intergovernmental panel concluded that if emissions of heat-trapping gases like carbon dioxide were not significantly reduced, the region could end up bereft of floating ice in summers sometime between 2050 and the early decades of the next century.

For the new study, Stroeve and others at the ice center reviewed nearly six decades of measurements by ships, airplanes and satellites estimating the maximum and minimum area of Arctic sea ice, which typically is greatest in March and smallest in September.

With an expert from the U.S. National Center for Atmospheric Research, also in Boulder, they then compared the observed trends with the projections made for the UN climate panel's review using the world's most advanced computer models of climate.

Stroeve's team found that since 1953, the area of sea ice in September has declined at an average rate of 7.8 percent a decade.

Computer climate simulations of the same period had an average rate of ice loss of 2.5 percent a decade.

The finding implies that the Arctic ice may be quicker to respond to warming as concentrations of heat-trapping gases rise in coming decades, said Marika Holland, another author of the new paper and a computer modeler at the Boulder climate center.

The month of April was so warm and so dry across Western Europe that it rewrote the weather record books in country after country, national weather services said, as hot air masses from Africa and the effects of a changing climate combined to drive up temperatures and drive away rain.

April 2007 was the eighth consecutive month of higher-than-normal temperatures in Germany, and the 13th straight month of unusually warm conditions in France, national weather services said Monday.

The British Met Office said last week that April - and the 12 months ending in April - were set to be the warmest in the 350 years since the Central England Temperature has been kept.

In Italy, Luca Ciceroni, a meteorologist for Sky Italia's 24-hour news channel, said by telephone that the month would probably end as the hottest April on record there.