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No. 72: Nov-Dec 1990

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IS THE ARCTIC ICE COVER THINNING?

"In May 1987 a British submarine carried out an ice profiling experiment in the Arctic Ocean in which the route closely approximated that of an earlier voyage in October 1976. Over a zone extending more than 400 km to the north of Greenland there is evidence of a significant decrease in mean ice thickness in 1987 relative to that found in 1976. This thinning amounts to a loss of volume of at least 15% over an area of 300,000 km2 ." (Wadhams, Peter; "Evidence for Thinning of the Arctic Ice Cover North of Greenland," Nature, 345:795, 1990.)

In an accompanying discussion of the ice problem, A.S. McLaren et al note that since the late 1800s, Arctic researchers using drills have reported consistently that the Arctic ice thickness averaged 3-4 meters. U.S. subma-rine surveys concurred with these figures during cruises in 1960 and 1962. Satellite surveys of ice cover from 19781987 found no trends. In other words, other sources of data on the Arctic ice reveal little change. The new results, therefore, need further confirmation. (McLaren, A.S., et al; "Could Arctic Ice Be Thinning?" Nature, 345:762, 1990.)

From Science Frontiers #72, NOV-DEC 1990. 1990-2000 William R. Corliss