The thinning of ice sheets in Greenland and western Antarctica is far more extensive than was previously thought, according to new research published online today in the British journal Nature.

A new method of anaylzing the ice loss -- using laser measurements from a satellite -- was key to the discovery, and will likely lead to further research into this key component of climate change. The rate of glacial ice loss is important because it can cause sea levels to rise rapidly around the world.

Led by Hamish Pritchard of the British Antarctic Survey, the study found that the most profound ice loss from these two vast ice sheets is a result of glaciers speeding up where they flow into the sea.

The “thinning of Greenland and Antarctic ice-sheet ocean margins is more sensitive, pervasive, enduring and important than previously realized,” wrote the authors in the study.

In some parts of Antarctica, ice sheets have been losing 30 feet a year in thickness since 2003, according to the study.

"We were surprised to see such a strong pattern of thinning glaciers across such large areas of coastline – it's widespread and in some cases thinning extends hundreds of kilometres inland, said Pritchard.

“We think that warm ocean currents reaching the coast and melting the glacier front is the most likely cause of faster glacier flow. This kind of ice loss is so poorly understood that it remains the most unpredictable part of future sea level rise."

It’s so poorly understood that the Intergovernmental Panel on Climate Change, in its 2007 report, didn’t include glacial melt in their assessment of future global sea-level rise, which they predicted to be anywhere from seven to 23 inches by the end of the century.

“This could push it toward the high end of that range,” said Pritchard. “It’s a wake up call to look at the extent of this problem.”

The research team used 50 million laser readings from NASA's ICESat (Ice, Cloud and Land Elevation Satellite), which was launched in 2003 to study changes in the world's ice and land masses.

By Doyle Rice (The Associated Press contributed to this article.)

Photo: Image from ICEsat data shows the pattern of surface height change over the Antarctic and Greenland ice sheets for the 2003-2008 period (red shows lowering). Rapid lowering is concentrated on the ice streams and glaciers that drain West Antarctica and Greenland. (Pritchard)

Link:  http://blogs.usatoday.com/sciencefair/2009/09/thinner-ice-than-expected-in-greenland-antarctica.html