Water Power Cracks Ice Sheet (broadcast Friday, April 18th, 2008)

A researcher stands along the edge of one of the large fractures running through the lake basin following the 2007 drainage. Image courtesy of Sarah Das, WHOI

Scientists studying glaciers in Greenland have found that lakes of water on the surface of a glacier can quickly and completely cut all the way through to the base of the ice. "If there is a crack or defect in the surface that is large enough, and a sufficient reservoir of water to keep that crack filled, it can create a conduit all the way down to the bed of the ice sheet," said Sarah Das, one of the scientists on the project.

Writing in the journal Science, a team of researchers describe a lake of meltwater covering 2.2 square miles containing 11 billion gallons of water draining completely within 24 hours -- a flow rate exceeding that of Niagara Falls. The water from that lake appears to have cut completely through over 3200 feet of ice to the base of the glacier. The researchers are working to understand how events like this one affect the ice itself and its movements. In this segment, Ira talks with Ian Joughin of the University of Washington and Sarah Das of the Woods Hole Oceanographic Institution about the team's findings, and what it is like to conduct research on the ice. Teachers, find more information about using Science Friday as a classroom resource in the Kids' Connection.

Guests

Ian Joughin
Glaciologist, Polar Science Center
University of Washington
Seattle, Washington

Sarah Das
Assistant Scientist, Geology & Geophysics
Woods Hole Oceanographic Institution
Woods Hole, Massachusetts

Related Links

• NatGeo: Greenland Meltwater Can Drain Faster Than Niagara Falls
• Ars Technica: Greenland lake disappears under the ice

Segment produced by:Karin Vergoth

Image: Each summer, countless meltwater lakes and ponds form on top of the Greenland ice sheet, as sunlight and warm air melt the surface. The melt creates channels, streams, and moulins in the ice.
Image © Science

Image: Each summer, countless meltwater lakes and ponds form on top of the Greenland ice sheet, as sunlight and warm air melt the surface. The melt creates channels, streams, and moulins in the ice.
Sarah Das, WHOI

Image: The first sunset of summer over the Greenland ice sheet, July 22, 2007. A meltwater drainage channel lurks below.
Sarah Das, WHOI

Image: Glaciologist Sarah Das inserts a seismometer into a borehole in the ice.
Sarah Das, WHOI

Image: Meltwater rushes in a stream across the top of the Greenland ice sheet, July 2007.
Sarah Das, WHOI

Image: Researchers examine a crevasse near a recently drained meltwater lake basin in Greenland.
Ian Joughin, UW Polar Science Center

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