Approximately 80 percent of the surface of Greenland is covered by the Greenland Ice Sheet, the world’s second largest body of ice after the Antarctic Ice Sheet. In June 2011, Dr. Marco Tedesco of the Department of Earth & Atmospheric Science, City College of New York (CCNY), led a team of scientists to Greenland to study surface features of the ice sheet and to collect data on solar energy being absorbed by the snow and ice.
One of the most dramatic features of ice sheets is the appearance of supraglacial lakes, pools of meltwater up to a few miles wide and 6 to 8 meters deep that form during the summer. What’s even more dramatic is that these lakes can disappear within hours, completely draining through vertical shafts called moulins that often extend all the way down to the bedrock under the ice. Tedesco captured some astonishing video of just such an event as Lake Ponting, near his campsite, vanished before his eyes. The footage, edited into the above film “meltzone 2011″ is to our knowledge the fist time the death of a supraglacial lake has ever been photographed. Tedesco described the experience in a two-part article for CCNY’s Alumnus magazine:
Standing at the bottom of the former lake right after its drainage was one of the most profound experiences of my fieldwork activities. After the lake had drained, large blocks of ice (up to five meters high and several meters wide that had been literally swirling on the lake like huge ice cubes in a giant cocktail glass while it drained) were spread around the moulin. This was swallowing water rushing from the top of the icy hills surrounding the lake. We could not see the bottom of the moulin but were able to see water heaving up from one of its walls and splashing against the opposite side in an enormously powerful and impressive way.
Studying these supraglacial lakes is important because once they drain, their water can have a lubricating effect on the bottom of the ice, accelerating its slide toward the sea. Tedesco and his team are currently analyzing the data they collected in Greenland to improve our capability to predict the impact of the Greenland ice melt on sea level rise.