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Posts Tagged ‘supraglacial lakes’

Greenland Melts 50 Days Longer

Posted by feww on February 18, 2011

Fahrenheit 451 minus 419

Melting in Greenland lasted 50 days longer than average in 2010


Click image to enlarge. Image acquired January 1, 2010 – December 31, 2010

“This image was assembled from microwave data from the Special Sensor Microwave/Imager (SSM/I) of the Defense Meteorological Satellites Program. Snow and ice emit microwaves, but the signal is different for wet, melting snow than for dry. Marco Tedesco, a professor at the City College of New York, uses this difference to chart the number of days that snow is melting every year. This image above shows 2010 compared to the average number of melt days per year between 1979 and 2009.” Source: NASA-EO

Greenland Melting – Short Movie


A short movie of videos and stills from Greenland collected by Marco Tedesco and his team in their 2009 and 2010 expeditions. “The theme is: meltwater. You will see canyons through which water flows, supraglacial lakes and ice cracks routing surface water to the bottom of the ice sheet. The vocal background at the beginning is a Shaman Inuit Chant.”

Posted in Climate Change, Cryosphere, global climate, meltwater | Tagged: , , , , | 1 Comment »

Vanishing Lakes

Posted by feww on April 18, 2008

Source: Media Relations

Researchers from the Woods Hole Oceanographic Institution (WHOI) and the University of Washington (UW) have for the first time documented the sudden and complete drainage of a lake of meltwater from the top of the Greenland ice sheet to its base.

From those observations, scientists have uncovered a plumbing system for the ice sheet, where meltwater can penetrate thick, cold ice and accelerate some of the large-scale summer movements of the ice sheet.

According to research by glaciologists Sarah Das of WHOI and Ian Joughin of UW, the lubricating effect of the meltwater can accelerate ice flow 50- to 100 percent in some of the broad, slow-moving areas of the ice sheet.


WHOI glaciologist Sarah Das stands in front of a block of ice that was raised up 6 meters by the sudden drainage of a meltwater lake in Greenland. (Photo by Ian Joughin, UW Polar Science Center)” Image may be copyrighted. See FEWW Fair Use Notice!

“We found clear evidence that supraglacial lakes—the pools of meltwater that form on the surface in summer—can actually drive a crack through the ice sheet in a process called hydrofracture,” said Das, an assistant scientist in the WHOI Department of Geology and Geophysics. “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.”

But the results from Das and Joughin also show that while surface melt plays a significant role in overall ice sheet dynamics, it has a more subdued influence on the fast-moving outlet glaciers (which discharge ice to the ocean) than has frequently been hypothesized. (To learn more about this result, read the corresponding news release from UW.)

The research by Das and Joughin was compiled into two complementary papers and published on April 17 in the online journal Science Express. The papers will be printed in Science magazine on May 9. Full press release Copyright ©2007 Woods Hole Oceanographic Institution, All Rights Reserved.

Posted in geology, Geophysics, glaciers, hydrofracture, Oceanography | Tagged: , , , , , , , , | 1 Comment »