The massive Arctic glacier believed to be responsible for calving the iceberg that sunk the Titanic is moving from the Greenland ice sheet and into the ocean at record speeds, according to a study in the journal The Cryosphere.
Jakobshavn Glacier is moving at a speed that appears the be the fastest ever recorded, researchers from the University of Washington and the German Space Agency (DLR) report.
"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," said lead study author Ian Joughin, a researcher at the Polar Science Center at the University of Washington.
Joughin and his team studied the glacier in 2012 and 2013, measuring dramatic speeds. In just one year it traveled more than 17 kilometers (10.5 miles), averaging a pace of 46 meters (151 feet) per day, a speed the researchers said is the fastest ever recorded for any glacier or ice stream in Greenland or Antarctica.
In the winter months the glacier's pace slows, but over the years, the quick-flowing summer pace of the Jakobshavn Glacier adds up. The glacier's average annual speed across the last few years is markedly faster than it was when the glacier's speeds were recorded in the 1990s.
To track the glacier's movements, the researchers used satellite data from NASA and the DLR.
"We used computers to compare pairs of images acquired by the German Space Agency's TerraSAR-X satellites. As the glacier moves we can track changes between images to produce maps of the ice flow velocity," Joughin said.
The increasing speed of the glacier is adding more ice to the ocean and contributing to sea-level rise, Joughin added.
"We know that from 2000 to 2010 this glacier alone increased sea level by about 1 mm. With the additional speed it likely will contribute a bit more than this over the next decade," he said.
As the Arctic region warms, glaciers there have begun to calve icebergs further and further inland, which means that even though the glacier is flowing towards the coast and carrying more ice into the ocean, its calving front is actually retreating, the researchers report, noting that during their study period the calving front retreated more than one kilometer inland than in the previous summer.
The increasing speed of the Jakobshavn Glacier coincided with this calving retreat.
"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.