New research suggests Greenland's largest glacier is moving ice from land to sea at record speeds.
"We are now seeing summer speeds more than four times what they were in the 1990s, on a glacier which at that time was believed to be one of the fastest, if not the fastest, glacier in Greenland," lead author Ian Joughin, a glaciologist at the University of Washington said in the news release.
In the summer of 2012 the Jakobshavn Glacier reached a speed of 10 miles per year (about 150 feet per day). This is believed to be the fastest flow rate of any glacier or ice stream in the region. The glacier flows much more slowly in the winter, but the glacier's average annual flow speed is about three times what it was in the 1990s.
"We know that from 2000 to 2010 this glacier alone increased sea level by about [.04] of an inch...With the additional speed it likely will contribute a bit more than this over the next decade," Joughin said.
The Jakobshavn Glacier has often been pegged as the object that caused the Titanic to sink back in 1912. It drains a nearby ice sheet and deposits it into a deep-ocean fjord.
"At its calving front, where the glacier effectively ends as it breaks off into icebergs, some of the ice melts while the rest is pushed out, floating into the ocean. Both of these processes contribute about the same amount to sea-level rise from Greenland," the news release reported.
Due to a warming climate this calving process has been moving inland. Jakobshavn's calving front is now located deeper in the fjord than it once was, which could explain the faster speeds.
"As the glacier's calving front retreats into deeper regions, it loses ice - the ice in front that is holding back the flow - causing it to speed up," Joughin said.
The team made their findings by looking at satellite data.
"We used computers to compare pairs of images acquired by the German Space Agency's satellites. As the glacier moves we can track changes between images to produce maps of the ice flow velocity," Joughin said.
By the end of this century the calving front could retreat as far back as the head of the fjord (about 31 miles upstream).
"The thing that's remarkable about the Jakobshavn Glacier is that even after all the mass that it has already lost, it is able to keep doing it, year after year," co-author Benjamin Smith, a glaciologist at the UW's Polar Science Center, said in the news release. "A smaller glacier would settle down after losing that much mass. Jakobshavn's ability to drain ice from the ice sheet is really exceptional among all of the glaciers in Greenland."
