Natural Solar Cycle Takes Its Toll
2004 09 22
WASHINGTON (Reuters) - Glaciers once held up by a floating ice shelf off Antarctica are now sliding off into the sea -- and they are going fast, scientists said on Tuesday.
Two separate studies from climate researchers and the space agency NASA show the glaciers are flowing into Antarctica's Weddell Sea, freed by the 2002 breakup of the Larsen B ice shelf.
Writing in the journal Geophysical Research Letters, the researchers said their satellite measurements suggest climate warming can lead to rapid sea level rise.
The teams at NASA's Jet Propulsion Laboratory in Pasadena, California, the National Snow and Ice Data Center at the University of Colorado in Boulder, and NASA's Goddard Space Flight Center in Greenbelt, Maryland, said the findings also prove that ice shelves hold back glaciers.
Many teams of researchers are keeping a close eye on parts of Antarctica that are steadily melting.
Large ice shelves in the Antarctic Peninsula disintegrated in 1995 and 2002 as a result of climate warming. But these floating ice shelves did not affect sea level as they melted.
Glaciers, however, are another story. They rest on land and when they slide off into the water they instantly affect sea level.
It was not clear how the loss of the Larsen B ice shelf would affect nearby glaciers.
But soon after its collapse, researchers saw nearby glaciers flowing up to eight times faster than before.
"If anyone was waiting to find out whether Antarctica would respond quickly to climate warming, I think the answer is yes," said Theodore Scambos, a University of Colorado glacier expert who worked on one study.
"We've seen 150 miles of coastline change drastically in just 15 years."
The affected area is at the far northern tip of the Antarctic, just south of Chile and Argentina. Temperatures there have risen by up to 4.5 degrees Fahrenheit (2.5 degrees C) in the past 60 years -- faster than almost any region in the world.
In the past 30 years, ice shelves in the region have lost more than 5,200 square miles of area.
"The Larsen area can be looked at as a miniature experiment, showing how warming can dramatically change the ice sheets, and how fast it can happen," Scambos said in a statement. "At every step in the process, things have occurred more rapidly than we expected."
But not all the melting in the Antarctic can be seen as a "miniature experiment."
The Ross ice shelf, for example, is the main outlet for the West Antarctic Ice Sheet, with several large glaciers that could, if they melted completely, raise sea levels by 16 feet.
"While the consequences of this area are small compared to other parts of the Antarctic, it is a harbinger of what will happen when the large ice sheets begin to warm," Scambos said. "The much larger ice shelves in other parts of Antarctica could have much greater effects on the rate of sea level rise."
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