Antarctic sediments muddy climate debate

3:16pm, September 5, 2001

Ocean-floor sediments drilled from Antarctic regions recently covered by ice shelves suggest that those shelves were only 2,000 years old. This finding could compel scientists to reassess whether the current destruction of polar ice is due primarily to human-caused global warming.

In the early 1990s, part of the ice shelf atop the Prince Gustav Channel, which separates the Antarctic peninsula and James Ross Island, broke apart. In the area formerly covered by the shelf, the channel's water depth is between 600 and 800 meters. Scientists collected sediment cores 5 to 6 m in length from the ocean floor in February and March 2000.

Scattered throughout the seafloor ooze were telling grains of rock, says Carol J. Pudsey, a geologist with the British Antarctic Survey in Cambridge, England. She and her colleague Jeffrey Evans separated the grains larger than about 1 millimeter from the smaller particles, which may have been washed into the area by ocean currents.

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