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Cracking up in Greenland

This researcher stands where hours earlier there was a lake, filled with melted ice water. Once drained, through a massive crack, scientists could step inside the lake bed and learn what happened. Sarah Das and Mark Behn at WHOI are investigating glacial lakes, which form atop Greenland’s ice sheet each spring and summer as returning sunlight melts ice and snow. They have found that as lake grow larger, large cracks can open up at their bases, allowing the lake water to drain in a dramatic surge all the way the bedrock at the bottom of glaciers. The water lubricates the base of the glacier, like grease on a railroad track, allowing glaciers to flow faster toward the coast and discharge more ice to the ocean.  As global temperatures rise, more lakes and cracks may form, accelerating the flow of ice to the sea.
(Photo by Chris Linder, Woods Hole Oceanographic Institution)