LATEST NASA FINDINGS:
Over 2T tons of ice melted in arctic since '03

Tue Dec 16, 7:10 AM EST

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.

NASA scientists planned to present their findings Thursday at the American
Geophysical Union conference in San Francisco. Luthcke said Greenland figures
for the summer of 2008 aren't complete yet, but this year's ice loss, while still
significant, won't be as severe as 2007.

The news was better for Alaska. After a precipitous drop in 2005, land ice
increased slightly in 2008 because of large winter snowfalls, Luthcke said. Since
2003, when the NASA satellite started taking measurements, Alaska has lost 400
billion tons of land ice.

In assessing climate change, scientists generally look at several years to determine
the overall trend. Melting of land ice, unlike sea ice, increases sea levels very
slightly. In the 1990s, Greenland didn't add to world sea level rise; now that island
is adding about half a millimeter of sea level rise a year, NASA ice scientist Jay
Zwally said in a telephone interview from the conference.
Between Greenland, Antarctica and Alaska, melting land ice has raised global sea
levels about one-fifth of an inch in the past five years, Luthcke said. Sea levels also
rise from water expanding as it warms.
Other research, being presented this week at the geophysical meeting point to
more melting concerns from global warming, especially with sea ice.
"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

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."

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