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The 2011 Arctic sea ice extent maximum that marks the beginning of the melt season appears to be tied for the lowest ever measured by satellites, say scientists at the University of Colorado Boulder's National Snow and Ice Data Center.

For the first time, the melting of glaciers in Greenland could now be measured with high accuracy from space. Just in time for the tenth anniversary of the twin satellites GRACE (Gravity Recovery and Climate Experiment) a sharp image has surface, which also renders the spatial distribution of the glacial melt more precisely. The Greenland ice shield had to cope with up to 240 gigatons of mass loss between 2002 and 2011. This corresponds to a sea level rise of about 0.7 mm per year. These statements were made possible by the high-precision measurements of the GRACE mission, whose data records result in a hitherto unequaled accurate picture of the earth's gravity. One of Newton's laws states that the gravity of an object depends directly on its mass. "When the mass of the Greenland ice sheet changes, so does the gravity there," explains Dr. Frank Flechtner from the GFZ German Research Centre for Geosciences. "The GRACE gravity field measurements therefore give us information on mass changes, including climate-related ones."