Principal Investigator (PI): Ian Joughin, University of Washington

Numerous recent studies have revealed rapid change in ice discharge from Greenland's outlet glaciers. A near doubling in flow speed of many of Greenland's glaciers substantially increased the rate at which the ice sheet calved icebergs to the ocean over the last five years. These results are significant in that they show Greenland's mass balance can fluctuate rapidly and unpredictably.

Despite the large magnitudes of these changes, we do not yet understand them well enough to predict their long-term impact on sea level. As a consequence, outlet glacier dynamics remain a "wild card" in the sea-level predictions included in the just-released Intergovernmental Panel on Climate Change Fourth Assessment Report (AR4). Improving such predictions and gaining a firm understanding of the dynamics that drive mass balance requires annual to sub-annual observations of outlet glacier variability (velocity and ice front position) to avoid aliasing of this rapidly varying signal.

The technology for measuring velocity in Greenland has matured to the point where we are well positioned to make such measurements. We have demonstrated this capability through earlier projects where we have mapped ice-sheet wide velocity and extent for 2000 and 2006. Here we proposed a comprehensive set of observations that will extend this time-series through the next five years, a period when Greenland is likely to continue to evolve rapidly with the current warming. In addition to providing products of utmost priority to the community currently trying to assess ice sheet stability, this project also will provide important baseline data for future generations.

Distributed by NASA's National Snow and Ice Data Center Distributed Active Archive Center (NSIDC DAAC)