NSIDC - Scientists May Have Underestimated Arctic Sea Ice Loss Rate - ABC [View All]

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The scientists say global warming means that summer melt backs are now dumping polar bears on land three weeks earlier each summer than in the mid-'70s, which means more hungry bears on land and more trouble for humans. "But sea-ice volume is what we really need to know," Serreze said. "It's the Holy Grail" for sea-ice experts, he says, adding that the news here is probably worse than any we've heard about sea-ice extent.

News from NASA that Arctic summer sea ice melted back 30 percent in the last 30 years — and could well be gone completely by about the year 2070 — made headlines in the summer of 2005. But those findings measured only the loss of surface area, not the thickness — thus the volume — of the ice. Satellites are close to being able to measure ice thickness accurately, Serreze said. New techniques are closing in on how to measure the amount of ice "freeboard" floating above the surface, which with a little fancy math can tell scientists the volume of the ice.

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Serreze cites work by Wieslaw Maslowski of the U.S. Navy Post Graduate School in Monterey, Calif., that strongly suggests it's not only Earth's warming atmosphere that is melting the Arctic ice from above.

"Wieslaw is saying it's also the warming sea currents melting the sea ice from below. He's been arguing that 2070 is way too far out in the future — way too conservative. I suspect he may be right," Serreze said.

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http://abcnews.go.com/Technology/GlobalWarming/story?id=2399066&page=1