Significant retreat has been seen in many glaciers worldwide. With increasing concern about the impact of global warming, there has been a concerted effort to monitor ongoing change. Projects such as Global Land Ice Measurements from Space (GLIMS) rely on the contributions of institutions worldwide to update a global database of digital glacier outlines. To a great extent, this effort relies on the manual extraction of glacier area from satellite optical instruments, such as the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). Unfortunately, dependence on optical imagery poses two significant challenges. First, clouds preclude the viewing of many glaciers, making periodic measurements impossible. Second, many alpine glaciers have significant debris cover, additionally complicating delineation of glacier extent from optical data. The sensitivity of synthetic aperture radar (SAR) coherence to motion offers a method for detecting glacial extent that is independent of weather and allows...