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West Antarctica warming fast

Temperature record from high-altitude station shows unexpectedly rapid rise

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10:52pm, December 21, 2012
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While the Arctic melts apace with rising global temperatures, Antarctica is often seen as the literal polar opposite — frigid, unyielding, impervious to change. But a spot in the heart of the West Antarctic Ice Sheet is one of the fastest-warming places on Earth, a new study shows.

From 1958 to 2010, the average temperature at the mile-high Byrd station rose by 2.4 degrees Celsius, researchers report online December 23 in Nature Geoscience. That warming is nearly twice what earlier, indirect studies had suggested. 

“It’s a big number — about as big as the most rapidly warming places elsewhere on the planet,” says study coauthor David Bromwich, a polar scientist at Ohio State University in Columbus. “We were quite surprised.”

Byrd is warming fastest in winter and spring, but Bromwich and his colleagues also say they detect a statistically significant temperature increase during the summer. If so, then even the frozen Antarctic interior is getting closer to melting.

“The impacts of warming here are potentially huge,” says David Schneider, a paleoclimatologist at the National Center for Atmospheric Research in Boulder, Colo. West Antarctica holds far more water locked up as ice than Greenland does, and melting from both great ice sheets has already raised sea levels 11 millimeters over the past two decades (SN: 12/29/12, p. 10).

That’s why scientists have been working to tease out whether Antarctica is warming or not. They know that parts of East Antarctica have been cooling, while places along the coast and on the Antarctic peninsula have been warming. But temperature records from the West Antarctic interior are few and far between.

The U.S. Navy established Byrd station in 1957 as part of the International Geophysical Year, and weather observers measured temperatures there until 1975. The station then fell into disuse and automated weather measurements began in 1980. Because of gaps and changes in the way weather data have been collected, many scientists had written off the Byrd record as too spotty to rely on.

But Bromwich’s team wanted to take a second look, since many indirect observations — such as measurements from ice cores and holes in the ice — suggest West Antarctica has indeed been getting warmer (SN: 2/14/09, p. 8). Bromwich and his colleagues, including graduate student Julien Nicolas, carefully stitched together the Byrd temperature data. (It helped that the automated weather station was sent back to Wisconsin in 2011 for an upgrade and a recheck of its instruments.) Then the scientists used a sophisticated computer simulation and further data analysis to fill in the missing temperature observations. “There’s no doubt it’s better than what was done before,” says Nicolas.

What happens at Byrd doesn’t stay at Byrd: Temperatures at the station track closely with temperatures over a wide swath of West Antarctica, Bromwich says. That suggests the ice sheet may approach melting much closer to the coast, where the ice extends onto the ocean as floating ice shelves that can destabilize and break apart, as the Larsen B shelf did in 2002. Such collapses contribute to sea level rise.

“The Arctic is receiving a lot of attention right now, as it should,” Bromwich says. “But what we are trying to emphasize here is that we need to pay attention to the other end of the Earth as well."

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