A NASA satellite image from September 21, 2005 and released on September 21, 2007 shows Arctic summer sea ice coverage in 2005.

WASHINGTON, April 2 (Xinhua) -- Summers in the Arctic may be ice-free in as few as 30 years, not at the end of the century as previously expected, according to a study released by U.S. National Oceanic and Atmospheric Administration (NOAA). The updated forecast is the result of a new analysis of computer models coupled with the most recent summer ice measurements.

"The Arctic is changing faster than anticipated," said James Overland, an oceanographer at NOAA's Pacific Marine Environmental Laboratory and co-author of the study, which will appear Friday in Geophysical Research Letters. "It's a combination of natural variability, along with warmer air and sea conditions caused by increased greenhouse gases."

Overland and his co-author, Muyin Wang, a University of Washington research scientist with the Joint Institute for the Study of the Atmosphere and Ocean in Seattle, analyzed projections from six computer models, including three with sophisticated sea ice physics capabilities. That data was then combined with observations of summer sea ice loss in 2007 and 2008.

The area covered by summer sea ice is expected to decline from its current 4.6 million square kilometers to about 1 million square kilometers. Much of the sea ice would remain in the area north of Canada and Greenland and decrease between Alaska and Russia in the Pacific Arctic.

"The Arctic is often called the 'Earth's refrigerator' because the sea ice helps cool the planet by reflecting the sun's radiation back into space," said Wang. "With less ice, the sun's warmth is instead absorbed by the open water, contributing to warmer temperatures in the water and the air."