Scientists said that warmer ocean temperatures caused an iceberg larger than the Chicago to break off Antarctica's Pine Island Glacier Monday, sending it flowing into the Amundsen Sea west of the continent.
German researchers used the TerraSAR-X, an earth-observing satellite, to observe
the new Antarctica iceberg bigger than Chicago, reported the science website LiveScience.com. The chunk of ice covers 278 square miles.
NASA's Operation IceBridgefirst first discovered a crack in the Pine Island Glacier in late 20111, according to LiveScience.com.
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"Using the images we have been able to follow how the larger crack on the Pine Island Glacier extended initially to a length of 28 kilometers [17 miles]," Nina Wilkens, a researcher from the Alfred Wegener Institute, said in a
statement. "Shortly before the 'birth' of the iceberg, the gap then widened bit by bit so that it measured around 540 meters [1,770 feet] at its widest point."
The Alfred Wegener Institute is a German research organization associated with the Helmholtz Association that conducts research in the Arctic, Antarctic and in the high and mid-latitude oceans.
A study released by NASA in June stated that warmer ocean waters are melting the undersides of the ice shelves in Antarctica. The study, which NASA said was the first to research all of the continent's ice shelves, discovered that underside melting accounted for 55 percent of the ice shelf mass loss from 2003 to 2008.
NASA said that Antarctica holds about 60 percent of Earth's fresh water within its ice sheets. Ice shelves buttress the glaciers behind them, controlling the speed at the continent's rivers of ice flow into the ocean.
Determining how ice shelves melt will help scientists improve projections of how the Antarctic ice sheet will respond to a warming ocean and contribute to sea level rise, according to NASA. The space agency said the melting will also will improve global models of ocean circulation by providing a better estimate of the amount of fresh water ice shelf melting add to Antarctic coastal waters.
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Angelika Humbert, a glaciologist with the Wegener Institute, said the flow of the Pine Island Glacier is based more on changing wind directions in the Amundsen Sea, and less by rising air temperatures.
"The wind now brings warm sea water beneath the shelf ice," Humbert said, according to LiveScience.com. "Over time, this process means that the shelf ice melts from below, primarily at the so-called grounding line, the critical transition to the land ice."
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