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Finding new causes for polar ice sheet changes

Mizzou Engineering Professor Curt Davis provided an international research team with satellite data on Antarctic ice sheet elevation, such as that shown above. Elevation changes are color-coded, with the red, orange and yellow areas showing places where the ice sheet has grown thinner. No data is available for the gray circular area. Image courtesy of Curt Davis

The Antarctic ice sheet may grow thinner or thicker from natural changes in snowfall that are unrelated to long-term trends, according to a recently released study co-authored by a University of Missouri engineering researcher.

Experts are keeping a particularly close eye on changes in polar ice sheet thickness and mass as possible indicators of global warming, with shrinkage linked to climate change. MU’s Curt Davis, an electrical and computer engineering professor, said results from the joint study in which he participated show how some modest changes in ice sheet thickness or elevation can be caused by natural phenomenon that have no relation to overall changes in mass.

“This study has no discernable impact on the effects of global climate warming on the Antarctic ice sheet,” Davis said. “What it shows is the complexity of ice sheet elevation change, and how numerous its causes may be.”

Researchers from the Institute for Marine and Atmospheric Research Utrecht (IMAU), in the Netherlands, the Royal Netherlands Meteorological Institute (KNMI) and the University of Newcastle in Australia used weather satellite data to build a computer model demonstrating how natural variations in snowfall may change Antarctic ice sheet elevation. With that model, the research team interpreted ice sheet elevation change measurements from 1995 through 2003 that Davis and MU Research Associate Yonghong Li gathered from separate satellite data.

The results of that study were published online on May 29 by the journal Science.

Natural fluctuations in snowfall on an ice sheet can at times weigh down and compress the snow beneath it, reducing the ice sheet’s elevation but not affecting longer-term changes in mass, the study found. Past polar ice sheet elevation studies did not take this phenomenon into account, Davis said.

Still, these new findings do not contradict other types of observations—including satellite measurements of ice sheet gravity and glacier velocity measurements—that indicate substantial losses of ice sheet mass in both Greenland and Antarctica, Davis said.

“Large negative changes in polar ice sheet elevations, such as those recorded in West Antarctica and Greenland coastal areas, can only be explained by significant losses of polar ice sheet mass,” he said.