Wednesday, February 19, 2014

Melting Ice Makes the Arctic a Much Worse Heat-Magnet Than Scientists Feared

Sea ice extent on September 9, 2011, the date of minimum extent for the year. Ice-covered areas range in color from white (highest concentration) to light blue (lowest concentration). Areas where the ice cover was less than 15 percent, including open water, are dark blue, and land masses are gray. The gold outline shows the median minimum ice extent for 1979-2000; that is, areas that were at least 15 percent ice-covered in at least half the years between 1979 and 2000. Based on sea ice concentration data from the National Snow and Ice Data Center. (Credit: Click to enlarge.
Dwindling sea ice in the Arctic Ocean is creating large areas of relatively dark ocean surface that reduce the albedo, or reflectivity, of the polar region.  More open water causes the Earth to absorb more of the sun's solar energy rather than reflect it back into the atmosphere.  A new study by researchers at Scripps Institution of Oceanography, UC San Diego, has found that the impact this phenomenon is having on global warming has likely been substantially underestimated.

"It's fairly intuitive to expect that replacing white, reflective sea ice with a dark ocean surface would increase the amount of solar heating," Kristina Pistone, a graduate student at Scripps who participated in the research, said in a statement.

However, the study, published Monday in the Proceedings of the National Academy of Sciences, used direct satellite measurements for the first time rather than computer models to determine that the magnitude of surface darkening has been two to three times as large as found in previous studies.

Melting Ice Makes the Arctic a Much Worse Heat-Magnet Than Scientists Feared

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