Newswise — For decades, researchers have debated whether global warming is occurring and the impact it has on society. Studying the polar ice sheets provides important information in assessing the changing climates of the world. In a new study, a University of Missouri-Columbia researcher found significant and widespread thinning of the southeastern portion of the Greenland ice sheet, indicating that climate change may be affecting the sheet.

"The significant thinning along the southeast Greenland coast found in a previous NASA study appears to have moved into the interior areas of the ice sheet that feeds ice to the glaciers near the coast," said Curt Davis, an electrical engineering professor at MU and an expert in satellite mapping. "This thinning may be related to climate change because long-term imbalances like this indicate that something is not normal."

Davis and MU research associate Shihua Sun analyzed data from the Geosat Follow On (GFO) satellite and previous satellites to measure ice sheet elevation changes over several time periods: 1978 to 1988, 1985 to 2002 and 1978 to 2002. According to Davis, GFO provides three times the information compared to previous satellites, which allows more measurements over a wider coverage area.

The satellite data showed widespread thinning of 4 inches per year reported between 1985 and 2002 for the upper elevation portions of the southeast Greenland ice sheet. According to Davis, previous NASA studies showed thinning rates of 3 to 6 feet per year in Greenland's southeast coastal glacier outlets. These rates decreased inland and were around 4 inches per year for some locations at elevations as high as 6,000 feet.

Davis' study shows the upper elevation thinning in southeast Greenland has been widespread and has existed for at least several decades. This, combined with the previous NASA results, indicates the coastal outlet glacier thinning is likely responsible for the thinning observed in the upper elevations, Davis said.

"The new results show over the past several decades there has been more ice loss in the southeast interior of the ice sheet, and this is probably due to the coastal glaciers discharging more ice into the ocean," Davis said. "In addition, snow precipitation, which thickens the ice, is not happening fast enough to make up the difference."

The study, funded by NASA's Cryospheric Sciences Program, recently was published in IEEE Geoscience and Remote Sensing Letters.

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IEEE Geoscience and Remote Sensing Letters (2004)