Glacier Hazards From Space

While most glacier hazards are felt locally, one has a global impact, and that is sea-level rise caused by the rapid melting or discharging of glaciers. One of the glaciers of greatest such concern is Jakobshavn Isbrae in western Greenland. This is the world's fastest-moving glacier, and between 1997 and 2003, it nearly doubled its speed and discharge of ice. The image at right shows the striking retreat between 2001 and 2004 of Jakobshavn's calving front—the leading edge where the glacier breaks off into icebergs that eventually get pushed out to sea. Apart from local hazards to shipping from more icebergs, such enhanced ice release to the ocean from this and other fast-moving glaciers has the potential to significantly increase global sea-level rise, which is currently about two to four millimeters per year. While this may sound modest, over decades the cumulative effect will mean increased flooding to coastal communities, with adjustments to harbors, seawalls, and other coastal infrastructure reaching into the billions of dollars.