Melting Antarctic Ice Causing Sea Levels to Rise

By Armando Duke

Houston, TX - Satellite surveys show that ice is melting in Antarctica faster than snowfall can replenish it, which is causing sea levels to rise. Two separate studies showed varying results. But both studies drew the same conclusion that the ice in Antarctica is melting rapidly. The only difference between the two studies was the degree that sea levels were rising.

The authors work in both studies added weight to the evidence that global warming was affecting sea levels. Earlier estimates were that global warming was causing an increase in rainfall that would generate more snow in Greenland and the Antarctic, replacing the ice that was grumbling into the sea. "Snowfall will matter less and less," said Robert Bindschadler, an expert on polar ice at the National Aeronautics and Space Administration. Bindschadler was not involved in either study.

Satellite images show that most of the ice is being lost in western Antarctica, where warming air and seawater have recently broken up huge floating shelves of ice. A survey led by H. Jay Zwally, a NASA scientist, used satellites and aircraft to measure changes in the height of ice sheets in Antarctica and Greenland over the decade ended in 2002.

A second study by scientists at the University of Colorado looked at changes from 2002 to 2005 using a pair of NASA satellites that detect subtle changes in Earth's gravitational field that can be used to estimate the weight of water in an ice sheet.

Zwally's study found a loss of volume in Antarctica and a small overall gain in Greenland, where inland snows have outpaced ice flowing into the sea. Zwally published his findings in the Journal of Glaciology.

Scientists at the University of Colorado found that changes in the ice were a good indicator of the changing climatic conditions there. Their study was published in the Journal of Science.

The National Oceanic and Atmospheric Administration said the Colorado team's estimate of 35 cubic miles of ice being lost annually in Antarctica fit well with current ideas about what was causing the rise in sea level.