Break Up of Ward Hunt Ice Shelf

February 02, 2004


Provided by: Earth Observatory, NASA GSFC
Summary authors & editors: Earth Observatory; Jim Foster

The Ward Hunt Ice Shelf (a portion of which is shown above) is located on the northern part of Ellesmere Island, in the Canadian Archipelago, less than 500 miles (800 km) from the North Pole. It was first realized that the Ward Hunt Ice Shelf was breaking up during August of 2002, when the above RADARSAT satellite image was acquired -- note the huge crack nearly bisecting the ice shelf. However, by looking at historical RADARSAT data, geophysicists Derek Mueller, Warwick Vincent, and Martin Jeffries determined that the ice shelf actually began to crack as early as April 2000. This ice shelf had been gradually but inexorably declining over the past century. Ice shelves are essentially large pieces of floating ice affixed to a land mass. Though the Ward Hunt is very small compared to Antarctic ice shelves, its breakup is nonetheless significant. It's known to have been in existence for at least 3,000 years.

When the Ward Hunt Ice Shelf began to fracture, an epishelf lake suddenly drained, spilling more than 3 billion cubic meters of fresh water into the Arctic Ocean. The Ward Hunt had dammed this epishelf lake, a body of freshwater that floats on denser ocean water, centuries ago. This epishelf lake is host to a tenuous ecosystem and was the largest and best-understood epishelf lake in the Northern Hemisphere. Because the Ward Hunt Ice Shelf is not fed by glaciers, its existence depends on snowfall and ice accumulation on its surface and freshwater freezing on the bottom. Now that the freshwater has been mostly removed, the fate of the Ward Hunt looks grim indeed.

Image courtesy of the Alaska Satellite Facility, Geophysical Institute, University of Alaska Fairbanks.

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