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Antarctic Ice Shelf Collapses

19 March 2002 (All day)
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A hunk of ice bigger than Rhode Island broke off from the Antarctic Peninsula last month, shattering into a flotilla of icebergs (see satellite image below). The final collapse of the northern half of the Larsen B ice shelf appears to be the latest dramatic sign of warming on the peninsula.

Temperatures on the peninsula have been rising five times faster than the global average--2.5°C since the 1940s--but whether global warming is to blame isn't yet known. The Larsen B ice shelf on the peninsula's east side is a floating sheet of ice about 200 meters thick. Its gradual breakup made headlines in 1998, when British scientists predicted its collapse (ScienceNOW, 17 April 1998). But the death throes of the shelf's northern half--3250 km2 have broken off since 31 January--is "spectacular in terms of the area and speed," says Ted Scambos of the University of Colorado, Boulder. U.S., British, and Argentine scientists have monitored the collapse using satellites, planes, and ships.

Scambos's group predicted the final Larsen B collapse using a model that looks at how much meltwater has pooled on the surface of the ice, and he now hopes to apply the model to bigger Antarctic ice shelves. Losing those shelves could presage the melting of their parent ice sheets on land--which could lead to a dramatic rise in sea level.

Related sites
British Antarctic Survey
U.S. Antarctic programs

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