3 January 2013

Antarctic ice sheet warming much faster than previously thought

by Will Parker

Remote monitoring equipment on the western part of the massive West Antarctic Ice Sheet (WAIS) is showing an increase of 4.3 degrees Fahrenheit (2.4 degrees Celsius) in average annual temperature since 1958 - around three times faster than average global temperature rises. A study detailing the temperature record from Byrd Station, appearing in the journal Nature Geoscience, reveals warming trends during the summer months of the Southern Hemisphere (December through February) for the first time.

"Our record suggests that continued summer warming in West Antarctica could upset the surface mass balance of the ice sheet, so that the region could make an even bigger contribution to sea-level rise than it already does," said David Bromwich, professor of geography at Ohio State University and senior research scientist at the Byrd Polar Research Center. "Even without generating significant mass loss directly, surface melting on the WAIS could contribute to sea level indirectly, by weakening the West Antarctic ice shelves that restrain the region's natural ice flow into the ocean."

According to study co-author Andrew Monaghan, from the National Center for Atmospheric Research, the new findings place West Antarctica among the fastest-warming regions on Earth. "We've already seen enhanced surface melting contribute to the breakup of the Antarctic's Larsen B Ice Shelf, where glaciers at the edge discharged massive sections of ice into the ocean that contributed to sea level rise," Monaghan said. "The stakes would be much higher if a similar event occurred to an ice shelf restraining one of the enormous WAIS glaciers."

The WAIS is considered especially sensitive to climate change since the base of the ice sheet rests below sea level and is vulnerable to direct contact with warm ocean water. Its melting currently contributes 0.3 mm to sea level rise each year - second to Greenland, whose contribution to sea-level rise has been estimated as high as 0.7 mm per year.

Aside from offering a more complete picture of warming in West Antarctica, the researchers hope their work underscores the need for a larger network of meteorological observation stations throughout West Antarctica.

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Source: National Science Foundation