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GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L22502, doi:10.1029/2005GL024737, 2005

Rapid retreat and acceleration of Helheim Glacier, east Greenland

I. M. Howat

Department of Earth Sciences, University of California, Santa Cruz, California, USA


I. Joughin

Applied Physics Lab, University of Washington, Seattle, Washington, USA


S. Tulaczyk

Department of Earth Sciences, University of California, Santa Cruz, California, USA


S. Gogineni

Center for Remote Sensing of Ice Sheets, University of Kansas, Lawrence, Kansas, USA


Abstract

A significant amount of the measured coastal thinning of the Greenland ice sheet may be due to recent acceleration of outlet glaciers. Using remote sensing, we measured two major periods of speedup on Helheim Glacier between 2000 and 2005 that increased peak speeds from approximately 8 to 11 km/yr. These speedups coincided with rapid retreats of the calving front, totaling over 7.5 km. The glacier also thinned by over 40 m from 2001 to 2003. Retreat of the ice front appears to decrease resistance to flow and concentrates the gravitational driving force over a smaller area. Farther up-glacier, acceleration may be a delayed response to surface draw-down and steepening of the glacier's main trunk. If the 2005 speedup also produces strong thinning, then much of the glacier's main trunk may un-ground, leading to further retreat.

Received 22 September 2005; accepted 19 October 2005; published 22 November 2005.

Index Terms: 0726 Cryosphere: Ice sheets; 0720 Cryosphere: Glaciers; 0758 Cryosphere: Remote sensing; 0762 Cryosphere: Mass balance (1218, 1223); 0774 Cryosphere: Dynamics.

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Citation: Howat, I. M., I. Joughin, S. Tulaczyk, and S. Gogineni (2005), Rapid retreat and acceleration of Helheim Glacier, east Greenland, Geophys. Res. Lett., 32, L22502, doi:10.1029/2005GL024737.