Big Ice

Greenland Ice Mapping Project: Measuring rapid changes in ice flow

Summary

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 IPCC Fourth Assessment. 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 an earlier project where we mapped ice-sheet wide velocity and extent for 2000 and 2006. Our follow-on project provides 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.

The Canadian Space Agency acquired full coverage of Greenland for the winters of 2006/7 and 2007/8 and this full set of data will be processed. Wit RADARSAT data no longer available, we have partnered with DLR (Dana Floricioiu DLR PI) to acquire data on 20 major glaciers in Greenland. We are also investigating using PALSAR data from the Japan’s ALOS satellite to provide additional coverage.