Posted on 03/25/2008 11:02:27 AM PDT by NormsRevenge
A vast ice shelf hanging on by a thin strip looks to be the next chunk to break off from the Antarctic Peninsula, the latest sign of global warming's impact on Earth's southernmost continent.
Scientists are shocked by the rapid change of events.
Glaciologist Ted Scambos of the University of Colorado was monitoring satellite images of the Wilkins Ice Shelf and spotted a huge iceberg measuring 25 miles by 1.5 miles (41 kilometers by 2.5 kilometers - about 10 times the area of Manhattan) that appeared to have broken away from the shelf.
Scambos alerted colleagues at the British Antarctic Survey (BAS) that it looked like the entire ice shelf - about 6,180 square miles (16,000 square kilometers - about the size of Northern Ireland)- was at risk of collapsing.
David Vaughan of the BAS had predicted in 1993 that the northern part of the Wilkins Ice Shelf was likely to be lost within 30 years if warming on the Peninsula continued at the same rate.
"Wilkins is the largest ice shelf on the Antarctic Peninsula yet to be threatened," he said. "I didn't expect to see things happen this quickly. The ice shelf is hanging by a thread - we'll know in the next few days and weeks what its fate will be."
Aircraft reconnaissance
The BAS scientists sent an aircraft out on a reconnaissance mission to survey the extent of damage to the ice shelf.
Jim Elliot, who captured video of the breakout said, "I've never seen anything like this before - it was awesome. We flew along the main crack and observed the sheer scale of movement from the breakage. Big hefty chunks of ice, the size of small houses, look as though they've been thrown around like rubble - it's like an explosion."
An initial iceberg calved away from the Wilkins Ice Shelf on Feb. 28. A series of images shows the edge of the ice shelf proceeding to crumble and disintegrate in a pattern characteristic of climate-caused ice shelf retreats throughout the northern Antarctic Peninsula. The disintegration left a sky-blue patch of hundreds of large blocks of exposed old glacier ice floating across the ocean surface.
By March 8, the ice shelf had lost just over 220 square miles (570 square kilometers) of ice, and the disintegrated ice had spread over 540 square miles (1,400 square kilometers). As of mid-March only a narrow strip of shelf ice between Charcot and Latady islands was protecting several thousand more kilometers of the ice shelf from potentially breaking up.
The region where the Wilkins Ice Shelf lies has experienced unprecedented warming in the past 50 years, with several ice shelves retreating in the past 30 years. Six of these ice shelves have collapsed completely: Prince Gustav Channel, Larsen Inlet, Larsen A, Larsen B, Wordie, Muller and the Jones Ice Shelf.
Antarctic warming
The Wilkins Ice Shelf was stable for most of the last century until it began retreating in the 1990s. A previous major breakout occurred there in 1998 when 390 square miles (1,000 square kilometers) of ice was lost in just a few months.
"We believe the Wilkins has been in place for at least a few hundred years, but warm air and exposure to ocean waves are causing it to break up," Scambos said.
The Antarctic Peninsula has warmed faster than anywhere else in the Southern Hemisphere; temperature records show that the region has warmed by nearly 3 degrees Celsius during the past 50 years - several times the global average and only matched in Alaska.
Other parts of Antarctica, including the East Antarctic Ice Sheet, seem to be more stable, though areas of melt have been observed in recent years.
Melting in the Antarctic is different than the recent record melt in the Arctic. Antarctica is composed of ice sheets, or huge masses of ice up to 2.5 miles (4 kilometers) thick that lie on top of bedrock and flow toward the coast, and ice shelves, the floating extensions of ice sheets. Arctic ice is primarily sea ice, some of which persists year-round and some of which melts in the summer and freezes again in the winter.
Maybe rebunked?
http://www.middlebury.net/op-ed/global-warming-01.html
“At left is a screen shot from the Greenpeace web site, from a video which drips with the urgency of stopping the “melting” of the Arctic Ice Pack.
But look closely: Those are shear lines, where the ice has broken, not “melted”. Melting does not occur in particular paths across the ice sheet, except when being zapped by aliens in UFO’s.”
from that neck of the woods, not so long ago..
Images of Wilkins Ice Shelf Breakup
Source: Breakup of the Larsen B Ice Shelf: 15 February 1998 - 18 March 1999
http://nsidc.org/iceshelves/larsenb1999/wilkins.html
and an big file for a sat pic, 2.1MB
http://nsidc.org/cgi-bin/new/iceshelves_images.pl
Huh? This is sea ice. When sea ice melts it obviously has no effect on sea levels. It's already in the ocean. However, sea ice may bottle up glaciers, keeping them on land -- with this shelf out of the way, those glaciers may flow into the ocean, something that would, obviously, raise sea levels.
I don't think there are enough tugboats on the planet to tow an iceberg the size of Northern Ireland.
“By March 8, the ice shelf had lost just over 220 square miles (570 square kilometers) of ice, and the disintegrated ice had spread over 540 square miles (1,400 square kilometers).
The region where the Wilkins Ice Shelf lies has experienced unprecedented warming in the past 50 years, with several ice shelves retreating in the past 30 years. Six of these ice shelves have collapsed completely: Prince Gustav Channel, Larsen Inlet, Larsen A, Larsen B, Wordie, Muller and the Jones Ice Shelf.”
And yet we continue to live. The cities haven’t flooded, the crops haven’t failed. So what’s the big deal?
Gravity
And no one’s gettin’ fat except Mama Cass!
How does sea ice “bottle up” glaciers?
Sea ice is highly unstable and much softer than fresh water ice. In addition to that, there would be nothing to stop a glacier flow from pushing sea borne ice out of it’s way.
What stops most glacier movement is terrain. Mountain ranges are mostly responsible for holding Antarctica’s ice on the continent. There are a few ice flows where there are breaks in the mountainous terrain, so the ice flows to the ocean at those points.
HE COULD! ALL BY HISSELF!..........
If it comes down to a debate on whether the ice sheet is the victim of too much CO2 in the air or has been zapped by space aliens, I think the latter is more likely.
It reminds me of the time I tuned into Art Bell at about 2:00 am in the middle of a debate between two guys. The first guy was a nutcase who denied astronauts had ever been on the moon. The 2nd guy was much more rational and debunked (or maybe bunked) every one of the nutcase's tin foil hat arguments. He seemed very intelligent - until he got his chance to put forth his idea. He argued we had very well indeed landed on the moon, and there discovered a civilization living under glass domes-- which the government had kept a total secret all these years.
If only the goreball warming nutjobs were relegated to Art Bell -- instead of invading my back pocket.
Actually we don’t need more water, although it would be nice if we stop giving it to southern California. We’ve had record snowfall this year so the spring thaw should be fun.
I thought ya’ll had a drought going on!...............
If your ice is melting, you're drinking too slow.
Is this not an example of calving, meaning the glacier is getting bigger?
Maybe we can tow Northern Ireland to Antarctica?
That would solve the Irish re-unification issue, give them their own country free of London, and provide 360 degree ocean views for everyone who lives in a condo above the 25th floor.
Where’s Frederic Tudor when you need him?
Actually, our drought is finally over. Thanks to global warming, the snowpack is about 120% of normal this year. Some towns in the southwestern mountains have run out of places to put the stuff.
So you don't like my science? Too bad. The Zuben house established a consensus and we predict the coastal cities will be flooded. Anything less is bunk, according to our consensus.
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