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Study Busts Antarctica's Chill On Global Warming

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Study Busts Antarctica's Chill On Global Warming

Environment

Study Busts Antarctica's Chill On Global Warming

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ROBERT SIEGEL, host:

Scientists who study global warming are especially interested in Antarctica - that's because the melting of Antarctic ice could obliterate coastlines around the globe. The continent's peninsula that jets towards South America has been warming rapidly, but scientist have been puzzled in the past by findings that the rest of the continent seem to be getting cooler. Well, now a study suggests that large parts of Antarctica have in fact been heating up, as NPR's Richard Harris reports.

RICHARD HARRIS: Antarctica is so remote, scientists didn't even put permanent weather stations there until 1957 and even those were in just a few scattered places. Eric Steig at the University of Washington says that made it hard to take the continent's temperature.

Dr. ERIC STEIG (Earth and Space Sciences, University of Washington): I like to say it's a bit like having data in San Francisco and New York and trying to say something about Arizona. You really need some more information if you're going to say anything reasonable about Arizona.

HARRIS: Steig and his colleagues have done just that for Antarctica, taking the sparse temperature records of the past 50 years and combining them with satellite records that cover a much greater area, but don't go so far back in time. The result, as they now report in the journal Nature, is that a big chunk of Antarctica, the western part of the continent, has in fact been warming up like the rest of the world, where temperatures have risen by about a degree near the equator to more than five degrees near the North Pole.

Dr. STEIG: It's much less than Arctic warming, but it is pretty much is on par with global average warming.

HARRIS: Now, Steig says warming isn't necessarily all bad news. Up to a point, Antarctic warming can actually reduce sea level. Warming can take water out of the ocean through evaporation and deposit it on the continent in the form of increased snowfall.

Dr. STEIG: West Antarctica should be getting more precipitation along with this increased temperature. But I think the data to demonstrate that are not really available.

HARRIS: In fact, the best data from Antarctica showed that the continent is putting slightly more water into the ocean than it's taking out. Now, the fact that Antarctica is in fact warming up is reassuring in a way to Arctic scientist Richard Alley at Penn State University.

Dr. RICHARD ALLEY (Geosciences, Pennsylvania State University): The world looks a little more sensible to me than it did before.

HARRIS: Scientists expect that Antarctica should be heating up according to what they understand about global warming. And the consequence of warming Antarctic air is not cause for panic, Alley says.

Dr. ALLEY: For now, most of the Antarctic is still so cold that it's very hard to melt it from above. The big question for Antarctica for the near future is what happens to the ocean because the warm ocean waters can circulate under the floating extensions of the Antarctic - the ice shelves.

HARRIS: And if warmer water melts those ice shelves, they'll release mountains of ice behind them into the ocean. Scientists have already seen the consequences of that along the relatively warm Antarctic Peninsula. There, at least eight large ice shelves have melted away in recent decades.

David Vaughan from the British Antarctic Survey is on the peninsula right now, keeping a close eye on the Wilkins Ice Sheet, which was once larger than Connecticut, but could soon be gone entirely.

Dr. DAVID VAUGHAN (Principal Investigator, British Antarctic Survey): We landed on the ice shelf just two days ago, flimsy looking piece of ice, and that appears to be hanging on by the skin of its teeth.

HARRIS: It could collapse in the next few weeks, he says.

Dr. VAUGHAN: Not all of Wilkins will disappear overnight, but a large part of it could.

HARRIS: That ice sheet is already floating on the ocean, so when it melts it won't raise sea level. But it's a powerful reminder that change can come quickly and dramatically in this land of ice. Richard Harris, NPR News.

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