Earlier this month, Greenland’s massive and rapidly-melting Jakobshavn Glacier lost what some experts believe may have been the largest chunk of ice ever observed, and now NASA scientists have released startling new before-and-after images of the frozen floating mass.
According to The Washington Post, the new images were collected by Joshua Stevens of the US space agency’s Earth Observatory using Landsat 8’s Operational Land Imager. They show what the front of the glacier looked like on July 31, prior to the calving event, and on August 16, after the nearly five square-mile chunk of ice separated from the glacier.
Additional satellite images posted on the Arctic sea ice blog indicate that the ice had broken off no more than 48 hours before the Landsat 8 probe captured their images. Preliminary estimates indicate that the area of ice lost during the calving event may be the largest on record, but NASA cautions that the pictures cannot show whether or not the ice was lost all at once.
“The calving events of Jakobshavn are becoming more spectacular with time, and I am in awe with the calving speed and retreat rate of this glacier,” Eric Ringot, a glaciologist with the Jet Propulsion Laboratory (JPL) in Pasadena, California, explained in a statement. “These images are a very good example of the changes taking place in Greenland.”
Glacier’s ice front continues to retreat inland
“What is important,” he added, “is that the ice front, or calving front, keeps retreating inland at galloping speeds.” University of Washington glaciologist Ian Joughin pointed out that at the end of each summer for the past several years, Jakobshavn’s calving front has moved approximately 600 meters (2,000 feet) farther inland than the summer before.
This ongoing retreat, NASA said, coincides with faster rates of flow. During the summer of 2012 the glacier accelerated to speeds not seen before, surging at a rate of 17 kilometers (10 miles) per year. On average, Jakobshavn moved three times faster in 2012 than it did during the mid-1990s, which is important because of its potential contributions to sea level increase.
The question remains: was this the largest chunk of ice ever lost from the glacier? Richard Alley, a glaciologist at Pennsylvania State University, told The Washington Post, “Overall, I don’t think that they really can nail the ‘largest’ [calving event] or not,” as the ice loss might have been due to multiple smaller events. Even so, he said, “it is not good news.”
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Feature Image: NASA Earth Observatory/Joshua Stevens
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