Scientists say NASA satellite data on global warming 'should alarm people'
Associated Press updated 5:48 a.m. ET, Tues., Dec. 16, 2008
WASHINGTON - More than 2 trillion tons of land ice in Greenland, Antarctica and Alaska have melted since 2003, according to new NASA satellite data that show the latest signs of what scientists say is global warming.
More than half of the loss of landlocked ice in the past five years has occurred in Greenland, based on measurements of ice weight by NASA's GRACE satellite, said NASA geophysicist Scott Luthcke. The water melting from Greenland in the past five years would fill up about 11 Chesapeake Bays, he said, and the Greenland melt seems to be accelerating.
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"It's not getting better; it's continuing to show strong signs of warming and amplification," Zwally said. "There's no reversal taking place."
Scientists studying sea ice will announce that parts of the Arctic north of Alaska were 9 to 10 degrees warmer this past fall, a strong early indication of what researchers call the Arctic amplification effect. That's when the Arctic warms faster than predicted, and warming there is accelerating faster than elsewhere on the globe.
As sea ice melts, the Arctic waters absorb more heat in the summer, having lost the reflective powers of vast packs of white ice. That absorbed heat is released into the air in the fall. That has led to autumn temperatures in the last several years that are six to 10 degrees warmer than they were in the 1980s, said research scientist Julienne Stroeve at the National Snow and Ice Data Center in Boulder, Colo.
That's a strong and early impact of global warming, she said.
"The pace of change is starting to outstrip our ability to keep up with it, in terms of our understanding of it," said Mark Serreze, senior scientist at the National Snow and Ice Data Center in Boulder, Colo., a co-author of the Arctic amplification study.
Two other studies coming out at the conference assess how Arctic thawing is releasing methane — the second most potent greenhouse gas. One study shows that the loss of sea ice warms the water, which warms the permafrost on nearby land in Alaska, thus producing methane, Stroeve says.
A second study suggests even larger amounts of frozen methane are trapped in lakebeds and sea bottoms around Siberia and they are starting to bubble to the surface in some spots in alarming amounts, said Igor Semiletov, a professor at the University of Alaska in Fairbanks. In late summer, Semiletov found methane bubbling up from parts of the East Siberian Sea and Laptev Sea at levels that were 10 times higher than they were in the mid-1990s, he said based on a study this summer.
The amounts of methane in the region could dramatically increase global warming if they get released, he said.
That, Semiletov said, "should alarm people."
The reason the release of methane is particularly alarming is that it has a much stronger greenhouse effect than the more common carbon dioxide.
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