Science / Medicine : Greenland Ice Sheet Growing

Using a satellite-based altimeter, researchers from the National Aeronautics and Space Administration have found that the Greenland Ice Sheet has been growing thicker at a rate of about 0.9 inches per year since 1975. Meteorologist H. Jay Zwally and his colleagues at the Goddard Space Flight Center in Greenbelt, Md., conclude in an article published last week in Science that the thickening results from increased snowfall caused by warming through the greenhouse effect.

Researchers had suggested earlier this month that global warming, which causes more water to evaporate from the oceans and thereby leads to more precipitation in many areas of the world, would cause a thickening of the Antarctic Ice Sheet. The new results suggest that the phenomenon may occur in the Arctic as well.

Scientists have feared that global warming would lead to melting of the polar ice sheets, causing the oceans to rise and inundate coastal lands. The new results suggest that trapping of water in the ice sheets may partially offset that melting, leading to a lower overall increase in ocean levels, perhaps as little as 12 inches.