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April 2, 2009
Mean sea ice thickness in meters for March (left) and September (right) based on six models. Top panels: September ice extent reached the current level by these models. Bottom panels: Arctic reached nearly "ice-free summer" conditions.
High resolution (Credit: University of Washington / NOAA)
Summers in the Arctic may be ice-free in as few as 30 years, not at the end of the century as previously expected. 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 April 3 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.
Data visualization: Arctic sea ice.
Visualization (Credit: NOAA)
The area covered by summer sea ice is expected to decline from its current 4.6 million square kilometers (about 1.8 million square miles) to about 1 million square kilometers (about 390,000 square miles) – a loss approximately two-fifths the size of the continental U.S. 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.”
NOAA understands and predicts changes in the Earth’s environment, from the depths of the ocean to the surface of the sun, and conserves and manages our coastal and marine resources.