Wednesday, February 24, 2010
Data show ice shelves are now disappearing all along the Antarctic Peninsula, including the southern, colder part.
The loss of the ice shelves could uncork the glaciers, drain ice from the land and increase sea levels.
The trend could conceivably extend to the rest of Antarctica, but researchers are still studying that.
A new report of ice shelf changes along the southern, colder part of the Antarctic Peninsula reveal some dramatic losses of ice over the last 63 years that the researchers attribute to global warming.
The report by the U.S. Geological Survey (USGS) compiles a wide variety of maps, aerial photos and satellite imagery to create a record of how the disappearance of floating ice shelves is increasing in the south of the peninsula, just as has happened in the north.
It's important, say the researchers, because as the ice shelves disappear, they uncork glaciers along the coast, which then pour more ice from the interior into the sea. That, in turn, contributes to sea levels rising, which threatens coasts worldwide.
"We have seen that the (disappearing ice shelves) effect has migrated south," said USGS's Jane Ferrigno, whose team included members of the British Antarctic Survey the Scott Polar Research Institute and Germany's Federal Agency for Cartography and Geodesy.
"The most noticeable and dramatic changes that can be seen on the Palmer Land area map are the retreat of the George VI, Wilkins, Bach and northern Stange Ice Shelves."
The Wilkin's Ice Shelf made news last year when a long, tenuous remaining bridge of ice connecting Charcot Island to the mainland finally gave way after shrinking for decades.
"That had been in place since ever since people have been going down there," Ferrigno told Discovery News. "Once that ice bridge was broken it makes the whole ice shelf vulnerable."
What's more, considering that the ice shelf flows in a direction that does not add ice to this area, there is little chance of the shelf recovering, she said.
The cause of the trend is not mysterious, says Antarctic ice researcher Eric Rignot of the University of California at Irvine.
"It's something that's very consistent with with the changing air temperatures," said Rignot...