BBC
BERLIN -A river of ice in Greenland has become the fastest-flowing glacier currently known in the world, a study suggests. In summer, the Jakobshavn Glacier - widely thought to have spawned the iceberg that sank the Titanic - is moving about four times faster than it was in the 1990s.
The Greenland Ice Sheet has seen record melting in recent years and would raise seal levels 6m were it all to vanish. Details of the research are published in The Cryosphere journal. Ian Joughin and Ben Smith of the University of Washington’s Polar Science Center in Seattle analysed pictures from the German TerraSAR-X satellites to measure the speed of the glacier.”As the glacier moves we can track changes between images to produce maps of the ice flow velocity,” said Dr Joughin, the study’s lead author.
In the summer of 2012, the glacier reached a record speed of more than 17km per year - more than 46m per day. “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,” Ian Joughin explained. The researchers noted that summer speeds are temporary, with the glacier flowing more slowly over the winter months.  But they added that even the annually averaged speed-up over the past couple of years is nearly three times what it was in the 1990s. Though Jakobshavn is now believed to be the fastest flowing feature of its type in the world, Prof Jonathan Bamber, a glaciologist from the University of Bristol, told BBC News.