Tuesday, September 8, 2015

Greenland's Jakobshavn Glacier sheds big ice

Scientists are studying a big mass of ice that has broken off the Jakobshavn Glacier in Greenland. They say the 12.4 sq km section is among the largest ever witnessed to come away from the ice stream's calving front. Satellite imagery suggests the break-up occurred sometime between 13 and 19 August.
Jakobshavn Glacier is a large outlet glacier in West Greenland.
Jakobshavn Glacier drains 6.5% of the Greenland ice sheet and produces around 10% of all Greenland icebergs. Some 35 billion tonnes of icebergs calve off and pass out of the fjord every year.
Jakobshavn glacier is the fastest moving glacier in the world.
The glacier lost a total area of 12.5 sq km, and assuming the ice is about 1,400m deep, then the volume calved would equate to about 17.5 cu km, "which could cover the whole of Manhattan Island by a layer of ice about 300m thick".

The end of every summer for the last several years has seen Jakobshavn’s calving front move about 600 meters (2,000 feet) farther inland than the summer before. Jakobshavn’s ongoing retreat coincides with faster rates of flow. In the summer of 2012, Jakobshavn accelerated to speeds not seen before, surging at a rate of 17 kilometers (10 miles) per year. On average, the glacier moved nearly three times faster in 2012 than it did in the mid-1990s.