The coastal portions of Kangerdlugssuaq and Helheim glaciers in southeast Greenland lost at least 51 1 8 km3 yr-1 of ice between 2001--2006 due to thinning and retreat, according to an analysis of sequential digital elevation models (DEMs) derived from stereo ASTER satellite imagery. The dominant contribution to this ice loss was dynamic thinning caused by the acceleration in flow of both glaciers. Peak rates of change, including thinning rates of ~90 m yr-1, coincided with the rapid increases in flow speed. Extrapolation of the measured data to the ice divides yields an estimated combined catchment volume loss of ~122 1 30 km3 yr-1, which accounts for half the total mass loss from the ice sheet reported in recent studies. These catchment-wide volume losses contributed ~0.31 1 0.07 mm yr-1 to global sea level rise over the 5-year observation period with the coastal regions alone contributing at least 0.1 1 0.02 mm yr-1.