Environmental Protection

Ice Melting in Antarctica: Better than We Thought

New data that more accurately measures the rate of ice melting in Antarctica demonstrates how the continent is dealing with global warming.

In a study lead by an international team in Newcastle University, UK, re-calibrated scales that are able to 'weigh' ice sheets from space to a greater degree of accuracy than ever before, were used to discover that Antarctica is contributing less to sea-rise level than originally thought.

Instead, the large amount of water flowing away from West Antarctica through ice-melt has been partly cancelled out by the volume of water falling onto the continent in the form of snow, suggesting some past studies have overestimated Antarctica's contribution to fast-rising sea levels. Using Gravity Recovery and Climate Experiment (GRACE) satellite data, the team calculated ice sheet mass loss by more accurately mapping and removing the mass changes caused by the flow of rock beneath Earth's surface.

"We have tried to weigh the ice in the past but GRACE only measures the combined effect of the ice changes and the land mass changes occurring beneath the Earth's surface," explains Professor King, Professor of Polar Geodesy at Newcastle University. "The step forward we have made is to provide a better calculation of the land mass changes so we can correct the satellite measurements to more accurately calculate the changes in ice mass alone.

Most of the Antarctic land surface is covered by ice, which has made it difficult to determine where it is rising and falling and by how much. That has meant GRACE data hasn't been able to contribute as much as it could to help scientists understand if Antarctica was growing or shrinking. Since their launch in 2002, the GRACE satellites allow scientists to map Earth's gravity field every 30 days, mapping changes as mass moves around the Earth's surface as well as below it.

Newcastle University's Dr. Rory Bingham adds: "There are lots of measurements that tell us something about the recent state of the Antarctic Ice Sheet, but none of those measurements gives the complete picture.” This research starts to pull that picture together, providing the most accurate GRACE estimate so far of Antarctica's contribution to sea level as a whole, as well as identifying which regions are changing and which are not.

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