Slab of Antarctic ice shelf collapses amid warming

gdpetti

Inactive
A little surprised no one else posted this... had to look around online to find it... though it's on tv... wierd! Anyway, before the ice age kicks in, the 'warming' has to do its thing first.... in the next months to year or two anyway... fair use http://www.reuters.com/article/environmentNews/idUSN2529744920080326?sp=true
Slab of Antarctic ice shelf collapses amid warming

Wed Mar 26, 2008 3:59pm

WASHINGTON (Reuters) - Satellite images show that a large hunk of Antarctica's Wilkins Ice Shelf has started to collapse in a fast-warming region of the continent, scientists said on Tuesday.

The area of collapse measured about 160 square miles of the Wilkins Ice Shelf, according to satellite imagery from the University of Colorado's National Snow and Ice Data Center.

The Wilkins Ice Shelf is a broad sheet of permanent floating ice that spans about 5,000 square miles and is located on the southwest Antarctic Peninsula about 1,000 miles south of South America.

"Block after block of ice is just tumbling and crumbling into the ocean," Ted Scambos, lead scientist at the National Snow and Ice Data Center, said in a telephone interview.

"The shelf is not just cracking off and a piece goes drifting away, but totally shattering. These kinds of events, we don't see them very often. But we want to understand them better because these are the things that lead to a complete loss of the ice shelf," Scambos added.

Scambos said a large part of the ice shelf is now supported by only a thin strip of ice. This last "ice buttress" could collapse and about half the total ice shelf area could be lost in the next few years, Scambos added.

British Antarctic Survey scientist David Vaughan said in a statement: "This shelf is hanging by a thread."

"One corner of it that's exposed to the ocean is shattering in a pattern that we've seen in a few places over the past 10 or 15 years. In every case, we've eventually concluded that it's a result of climate warming," Scambos added.

Satellite images showing the collapse began on February 28, as a large iceberg measuring 25.5 by 1.5 miles fell away from the ice shelf's southwestern front leading to a runaway disintegration of the shelf interior, Scambos said.

A plane also was sent over the area to get photographs of the shelf as it was disintegrating, he added.

Scambos said this ice shelf has been in place for at least a few hundred years, but warm air and exposure to ocean waves are causing a breakup. In the past half century, the Antarctic Peninsula has witnessed a warming as fast as anywhere on the planet, according to scientists.

"The warming that's going on in the peninsula is pretty clearly tied to greenhouse gas increases and the change that they have in the atmospheric circulation around the Antarctic," Scambos said.

With Antarctica's summer melt season coming to an end, the he said he does not expect the ice shelf to disintegrate further immediately, but come January scientists will be watching to see if it continues to fall apart.

(Editing by Cynthia Osterman)
 

FarmerJohn

Has No Life - Lives on TB
National Geographic article on the same event:

http://news.nationalgeographic.com/news/2008/03/080326-AP-antarctica-.html

Huge Swath of Antarctica Ice Collapses

March 26, 2008
A chunk of Antarctic ice about seven times the size of Manhattan suddenly collapsed, putting an even greater portion of glacial ice at risk, scientists said Tuesday.

Satellite images show the runaway disintegration of a 160-square-mile chunk in western Antarctica, which started February 28.

This is the result of global warming, said British Antarctic Survey scientist David Vaughan.

Because scientists noticed satellite images within hours, they diverted satellite cameras and even flew an airplane over the ongoing collapse for rare pictures and video.

"It's an event we don't get to see very often," said Ted Scambos, lead scientist at the National Snow and Ice Data Center in Boulder, Colorado.

"The cracks fill with water and slice off and topple. … That gets to be a runaway situation."

Global Warming

While icebergs naturally break away from the mainland, collapses like this are unusual but are happening more frequently in recent decades, Vaughan said. (Related: National Geographic's Larsen Ice Shelf Expedition.)

The collapse is similar to what happens to hardened glass when it is smashed with a hammer, he said.

The rest of the Wilkins Ice Shelf, which is about the size of Connecticut, is holding on by a narrow beam of thin ice.

Scientists worry that it too may collapse. Larger, more dramatic ice collapses occurred in 2002 and 1995.

Vaughan had predicted the Wilkins shelf would collapse about 15 years from now. The part that recently gave way makes up about 4 percent of the overall shelf, but it's an important part that can trigger further collapse.

There's still a chance the rest of the ice shelf will survive until next year because this is the end of the Antarctic summer and colder weather is setting in, Vaughan said.

Scientists said they are not concerned about a rise in sea level from the latest event, but say it's a sign of worsening global warming.

Such occurrences are "more indicative of a tipping point or trigger in the climate system," said Sarah Das, a scientist at the Woods Hole Oceanographic Institution in Massachusetts.

"These are things that are not re-forming," Das said. "So once they're gone, they're gone."

Climate in Antarctica is complicated and more isolated from the rest of the world.

Much of the continent is not warming and some parts are even cooling, Vaughan said.

However, the western peninsula, which includes the Wilkins Ice Shelf, juts out into the ocean and is warming.

This is the part of the continent where scientists are most concern about ice melt triggering sea level rise.
 
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