Recent Greenland ice mass loss by drainage system from satellite gravity observations

Mass changes of the Greenland Ice Sheet resolved by drainage system regions were derived from a local mass concentration analysis of NASA - Deutsches Zentrum fur Luft- und Raumfahrt Gravity Recovery and Climate Experiment ( GRACE mission) observations. From 2003 to 2005, the ice sheet lost 101 +/- 16 gigaton/year, with a gain of 54 gigaton/year above 2000 meters and a loss of 155 gigaton/year at lower elevations. The lower elevations show a large seasonal cycle, with mass losses during summer melting followed by gains from fall through spring. The overall rate of loss reflects a considerable change in trend ( - 113 +/- 17 gigaton/ year) from a near balance during the 1990s but is smaller than some other recent estimates.