An ice bridge which had apparently held a vast Antarctic ice shelf in place during recorded history shattered on Saturday and could herald a wider collapse linked to global warming, a leading scientist said.
The satellite picture, from the European Space Agency (ESA), showed that a 40 km (25 mile) long strip of ice believed to pin the Wilkins Ice Shelf in place had splintered at its narrowest point, about 500 meters wide.
The Wilkins, now the size of Jamaica or the U.S. state of Connecticut, is one of 10 shelves to have shrunk or collapsed in recent years on the Antarctic Peninsula, where temperatures have risen in recent decades apparently because of global warming.
The ESA picture showed a jumble of huge flat-topped icebergs in the sea where the ice bridge had been on Friday, pinning the Wilkins to the coast and running northwest to Charcot Island.
The loss of the ice bridge, jutting about 20 meters out of the water and which was almost 100 km wide in 1950, may now allow ocean currents to wash away far more of the Wilkins shelf.
Nine other shelves have receded or collapsed around the Antarctic Peninsula in the past 50 years, often abruptly like the Larsen A in 1995 or the Larsen B in 2002 further north.
Cores of sediments on the seabed indicate that some of these ice shelves had been in place for at least 10,000 years.
In January, the remaining ice bridge had been surrounded by icebergs the size of shopping malls, many of them trapped in sea ice. A few seals were visible lolling on sea ice in the low Antarctic sunshine.
Temperatures on the Antarctic Peninsula have risen by up to about 3 Celsius (5.4 Fahrenheit) in the past 50 years, the fastest rate of warming in the Southern Hemisphere.
The loss of ice shelves does not affect sea levels — floating ice contracts as it melts and so does not raise ocean levels. But their loss can allow glaciers on land to slide more rapidly toward the sea, adding water to the oceans.
The Wilkins does not have much ice pent up behind it. But bigger ice shelves to the south on the frozen continent, where no major warming has been detected, hold back far more ice.
– from reuters. 6 Apr 2009