Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: THURSDAY, June 28, 1990 TAG: 9006280745
SECTION: NATIONAL/INTERNATIONAL PAGE: A/10 EDITION: EVENING
SOURCE: Associated Press
DATELINE: NEW YORK LENGTH: Medium
The 15 percent decline is large for an area where scientists had thought ice was consistently thick, said researcher Peter Wadhams.
But it is impossible to know whether global warming played any role, he said.
Wadhams, of the University of Cambridge in England, presented his Arctic ice study in today's issue of the British journal Nature.
Scientists predict a gradual warming of the Earth from a buildup of gases such as carbon dioxide in the atmosphere. The gases trap solar energy like a greenhouse around the Earth.
Such a warming could lead to hotter summers, altered rainfall patterns that could disrupt agriculture and flooding in coastal areas, scientists say.
Using data from submarine-based studies in 1976 and 1987, Wadhams calculated changes within a 112,000-square-mile triangle north of Greenland. That is slightly larger than Nevada.
Wadhams studied the thickness of the submerged portions of huge floating chunks of sea ice. That is a good indicator of total ice thickness.
He found that average thickness dropped from 17.5 feet in 1976 to 14.9 feet in 1987, about a 15 percent decrease. Over the study area, that corresponds to a loss of nearly 55 cubic miles of ice, he said.
The missing ice did not necessarily melt away. The main reason for the decrease, Wadhams suggested, may be that thick ice broke apart in the months before the 1987 reading. That would leave open water that would freeze into relatively thin ice. This would reduce the overall average thickness for the region he studied.
Such a mechanism would have nothing to do with global warming, John Walsh, a University of Illinois meteorology professor, said in an interview. But other factors may have been at work too, he said.
"The jury's still out on this," Walsh said.
Thinning of Arctic ice can be an early sign of global warming, Wadhams wrote. But it is impossible to tell whether global warming played any role in his findings, because he lacks data from between the two years he sampled or from years since 1987, he said.
The findings show that scientists must do more extensive monitoring to determine if Arctic ice is getting thinner or whether changes like the one he found are simply natural variations, he said.
A Nature editorial called the new results "provocative" and agreed that more studies will be needed to discern true trends in the ice thickness.
by CNB