One of the world’s fastest moving glaciers shed a huge chunk of ice. The loss of ice measured around 12.5 square kilometers (5 square miles), which is large enough to cover the whole of Manhattan Island.

Jakobshavn glacier in western Greenland is notorious for losing large chunks of ice, according to NASA. Satellite imagery shows that the glacier shed kilometers of ice sometime between August 14 and August 16. Some have speculated that the ice loss is the largest on record, but NASA argued on its Earth Observatory website that this is yet to be confirmed as “these estimates are preliminary, and satellite images from before and after an event cannot show whether the ice was lost all at once, or in a series of smaller events.”

The difference can be seen in the image below. The two images are 15 days apart and were taken by the Operational Land Imager (OLI) on the Landsat 8 satellite. The first image shows the glacier on July 31, before the calving event – when ice breaks away – and the second on August 16 after the ice calved.

^{Images show the before and after of ice calving event. Credit: NASA}

“Assuming the ice is about 1400 m [4,600 ft] deep, this equates a volume of 17.5 cubic km – which could cover the whole of Manhattan Island by a layer of ice about 300 m [984 ft] thick,” the European Space Agency wrote on its website.

“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,” said Eric Rignot, a glaciologist at the Jet Propulsion Laboratory, in a statement. “These images are a very good example of the changes taking place in Greenland.”

As a result of the calving event, the new face of the glacier has been pushed inland to its furthest easterly location since monitoring began in the mid-1880s. According to ESA, Jakobshavn is especially important for Greenland as it drains 6.5 percent of the Greenland ice sheet, producing roughly 10% of its icebergs.  

“What is important is that the ice front, or calving front, keeps retreating inland at galloping speeds,” Rignot said.

NASA noted on its website that Jakobshavn is retreating at a faster rate. On average in 2012, the glaciers moved nearly three times faster than it did in the mid-1990s. NASA suggests Jakobshavn could contribute more to sea level rise than “any other single feature in the Northern Hemisphere.”