In Brief
Glacial Melting Recorded from Space
The glacial retreat on Greenland could now be measured for the first time from space with a high degree of precision. In time for the tenth anniversary of the twin satellites GRACE (Gravity Recovery and Climate Experiment), the data provided by these satellites was processed to produce a high-resolution image rendering also a precise spatial distribution of the glacial melting. The Greenland ice sheet had to suffer up to 240 gigatonnes of mass balance loss per year between 2002 and 2011. This corresponds to a rise of the sea level by approximately 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."
