Earlier this month, European Space Agency (ESA) satellites imaged one of the most significant glacier calving events ever recorded. It all centered around the fastest moving glacier in the world – Jakobshavn glacier.
An enormous piece of ice, measuring 12.5 sq km, broke off the glacier sometime between August 14 and 16.
Sentinel-1A, a satellite that is part of Europe’s Copernicus program, used radar imaging to capture the before and after of the event. By comparing images from July 27, August 13 and August 19, the new leading edge of the glacier has been pushed inland by several kilometers. Scientists believe it’s the furthest east the Jakobshavn glacier’s face has been since monitoring began around 130 years ago.
The image above is a radar composite of three images taken on July 27 (red), August 13 (green) and August 19 (blue). It appears that between July 27 and August 13, the glacier advanced westward before the calving event. By August 19, the calving event led to a quick retreat of the ice front back to the east.
Here’s an optical image of the glacier. The chunk of ice that broke away is indicated on the right side of the image.
It’s hard grasp the scale of this calving event based on these pictures. Here’s how the ESA describes it:
“It is estimated that the glacier lost a total area of 12.5 sq km. Assuming the ice is about 1400 m 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 thick.”
Jakobshavn glacier is no stranger to huge calving events. One piece of measuring 7 sq km broke off earlier this year. Another around the same size broke off in 2010. This glacier drains 6.5% of the Greenland ice sheet. And it produces around 10% of its icebergs. Together, around 35 billion tons of ice calve every year.
Here’s what the calving front looks like closer to the ground.
Image credit: Wikipedia (Note: this image is not from the most recent calving event)
Watch ‘Chasing Ice’
What if cameras were set up for a similar calving event? In May 2008, Adam LeWinter and Director Jeff Orlowski captured the largest glacier calving event ever on film of the same glacier. The Jakobshavn Glacier (sometimes called Ilulissat Glacier) in Western Greenland retreated a mile across a calving face three miles wide. Set aside about five minutes and watch enormous chunks of ice soar out of the ocean 600 feet and then fall back into the ocean.
Chasing Ice won multiple awards including Excellence in Cinematography at the 2012 Sundance Film Festival and a 2013 Emmy for Outstanding Nature Programming.
Even with cameras on the ground, the enormity of calving events is hard to fathom.
Image credits: ESA