Rapid ice discharge from southeast Greenland glaciers

Interferometric synthetic-aperture radar (InSAR) observations of southeast Greenland glaciers acquired by the Earth Remote Sensing Satellites (ERS-1/2) in 1996 were combined with ice sounding radar data collected in the late 1990s to estimate a total discharge of 46 +/- 3 km³ ice per year between 62°N and 66°N, which is significantly lower than a mass input of 29 +/- 3 km³ ice per year calculated from a recent compilation of snow accumulation data. Further north, Helheim Glacier discharges 23 +/- 1 km³/yr vs 30 +/- 3 km³/yr accumulation; Kangerdlugssuaq Glacier discharges 29 +/- 2 km³/yr vs 23 +/- 2 km³/yr; and Daugaard-Jensen Glacier discharges 10.5 +/- 0.6 km³/yr vs 10.5 +/- 1 km³/yr. The mass balance of east Greenland glaciers is therefore dominated by the negative mass balance of southeast Greenland glaciers (-17 +/- 4 km³/yr), equivalent to a sea level rise of 0.04 +/- 0.01 mm/yr. Warmer and drier conditions cannot explain the imbalance which we attribute to long-term changes in ice dynamics.