World’s Fastest Moving Glacier Sheds Manhattan-sized Ice Chunk

The fastest moving glacier in the world shed a chunk of ice measuring around 12.5 sq km this week, satellite images show. This makes it one of the most significant calving events ever recorded. Radar images from the Sentinel-1A satellite show the Jakobshavn glacier in western Greenland before and after the event, which took place between 14 and 16 August.

The glacier’s new face has been driven inland by several kilometres to what appears to be its furthest easterly location since monitoring began in the mid-1880s. 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 drains 6.5% of the Greenland ice sheet, creating around 10% its icebergs. This amounts to some 35 billion tonnes of ice that calve every year.

Jakobsavn glacier

Radar images from Sentinel-1A captured the Jakobshavn glacier in western Greenland before and after a massive calving event, which took place between 14 and 16 August 2015. The image composite includes different Sentinel-1A images from 27 July, and 13 and 19 August. The red, green and blue indicate the position of the calving front and other dynamic features on each respective date. Credit: Copernicus Sentinel data (2015)/ESA

Similar events were documented showing the glacier parted with 7 sq km of ice, both earlier this year and back in 2010.

Studied for over 250 years, the Jakobshavn glacier has helped to develop our understanding of the importance of ice streams and glaciers in climate change, icecap glaciology, and how they affect sea level.

Icebergs are frequently so big they cannot easily float away. They hang around, sometimes for years, stuck on the bottom in shallower areas of the fjord until they finally melt enough to disperse, break into pieces or are pushed out by icebergs coming up from behind.

Photo: optical image of Jakobshavn glacier in western Greenland, acquired by Sentinel-2A on 16 August 2015, offers a valuable perspective of the scale of the calving event that took place between 14 and 16 August. The contour indicates the area of ice lost between images acquired on 6 and 16 August. All-weather radar images from the Sentinel-1A satellite provide a year-round view of glacier dynamics. Credit: Copernicus Sentinel data (2015)/ESA