Satellite images have revealed the collapse of Larsen B ice shelf on the Antarctic Peninsula, fulfilling predictions made by British Antarctic Survey (BAS) scientists. The collapse of the 3250 km2 ice shelf is the latest drama in a region of Antarctica that has experienced unprecedented warming over the last 50 years.
Earlier this month, Ted Scambos of the University of Colorado alerted BAS glaciologists David Vaughan and Chris Doake to images from the NASA MODIS satellite.
Meanwhile, in Antarctica, Argentinian glaciologist Pedro Skvarca realized that something was happening to the ice shelf and mobilized an aircraft to obtain aerial images confirming the satellite data.
While the collapse was still occurring, the BAS research ship RRS James Clark Ross navigated her way through the armada of icebergs to obtain photographs and samples.
Over the last month, the 200-m thick ice shelf collapsed into small icebergs and fragments. Pooling these new observations, scientists will determine when such an event last happened and which ice shelves are threatened in future.
BAS glaciologist Dr. David Vaughan said, "In 1998, BAS predicted the demise of more ice shelves around the Antarctic Peninsula. Since then, warming on the peninsula has continued and we watched as piece-by-piece Larsen B has retreated.
"We knew what was left would collapse eventually, but the speed of it is staggering," Vaughan said.
During the last 50 years, the Antarctic Peninsula has warmed by 2.5°C, much faster than mean global warming. One response to climate change has been the retreat of five ice shelves, floating extensions of the grounded ice sheet.
In 1998, scientists of the British Antarctic Survey used numerical models to predict the future of one ice shelf, Larsen B, and said that if it "were to retreat by a further few kilometers, it too is likely to enter an irreversible retreat phase" (Dr Chris Doake, Nature Vol. 391, pages 778-780).
The rate of warming on the Antarctic Peninsula is rapid and unmatched elsewhere in Antarctica (Vaughan et al., 2001 Science, Vol. 293, pages 1777-1779).
Since it is already floating, the disintegration of Larsen will have no impact on sea level. Sea level will rise only if the ice held back by the ice shelf flows more quickly onto the sea.
The collapsed ice shelf at 3250 km2 is larger than Luxembourg (2586 km2) or just smaller than Cambridgeshire (3409 km2).
British Antarctic Survey is responsible for most of the UK's research in Antarctica. It is a component of the Natural Environment Research Council.
Related website:
British Antarctic Survey
19-Mar-2002
