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19 November 2010
Antarctic Ice Bridge Breaks
Warmer temperatures in the Antarctic summer are causing massive ice sheets to break up and float away
NASA Images
The Wilkins Ice Shelf (above) in the Antarctic covers an area about the same size as Jamaica. Until recently, it was anchored to the Charcot and Latady islands by an ice bridge.
On April 5, 2009, BBC News reported that the ice bridge had snapped. This said the BBC could “mean the Wilkins Ice Shelf is on the brink of breaking away, and provides further evidence of rapid change in the region.”
Weakening Monitored for Fifteen Years
The British Antarctic Survey (BAS) has been keeping a close eye on the Wilkins Ice Shelf for a decade and a half. It is on the western side of the Antarctic Peninsula, which juts out from the continent towards the southern tip of South America.
In the late southern summer of 2008, a massive iceberg broke loose from the shelf. The BAS noted this in a press release in March 2008: “Scientists monitoring satellite images of the Wilkins Ice Shelf spotted that a huge (41 by 2.5 km) berg the size of the Isle of Man appears to have broken away in recent days – it is still on the move.”
Professor David Vaughan of the BAS had predicted in 1993 the Wilkins Ice Shelf would become a casualty of global warming.
When the large iceberg broke away in 2008 he said, “Wilkins is the largest ice shelf on the Antarctic Peninsula yet to be threatened. 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 or weeks what its fate will be.”
Ice Bridge Breaks
That thread survived the southern summer of 2008 but succumbed in 2009. BAS announced
on April 4, 2009 that the bridge had broken: “Satellite pictures, from the European
Space Agency (ESA), revealed that the 40-
Wilkins Ice Shelf in place had snapped at its narrowest point
of about 500 meters wide off the Antarctic Peninsula. As the ice shelf shattered
an armada of hundreds of small icebergs (left) was created.”
Professor Vaughan says that eight separate ice shelves along the Antarctic Peninsula have been retreating in the last few decades. He adds, “There is little doubt that these changes are the result of atmospheric warming on the Antarctic Peninsula, which has been the most rapid in the Southern Hemisphere.”
Now that the ice bridge has gone much of the Wilkins Ice Shelf is expected to break away in coming Antarctic summers. The loss of the shelf will not have a major impact on ocean levels because the ice is floating. However, the BBC points out the ice on the Peninsula itself will raise sea levels if it melts and that “…the Peninsula has been one of the fastest warming places on the planet.”
Image credit
Chelys
Sources
“Antarctic Ice Bridge Linking Islands ‘Snaps.’ ” Tom Leonard, The Telegraph, April 5, 2009.
“Ice Bridge Ruptures in Antarctic.” BBC News, April 5, 2009.
“Antarctic Ice Shelf ‘Hangs by a Thread.’ ” Press Release, British Antarctic Survey, March 25, 2008.
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“Scientists say data from satellites and weather stations indicate a warming of about 0.6C over the last 50 years [in the Antarctic].
“Writing in the journal Nature, they say the trend is ‘difficult to explain’ without the effect of rising greenhouse gas levels in the atmosphere.”
BBC News, January 2009