Updated History of Jakobshavn Glacier Recession (1850-2004) in Greenland. Since measurements of Jakobshavn Isbrae were first taken in 1850, the glacier has gradually receded, finally coming to rest at a certain point for the past 5 decades. However, from 1997 to 2003, the glacier has begun to recede again, this time almost doubling in speed. The finding is important for many reasons. For starters, as more ice moves from glaciers on land into the ocean, it raises sea levels. Jakobshavn Isbrae is Greenland's largest outlet glacier, draining 6.5 percent of Greenland's ice sheet area. The ice stream's speed-up and near-doubling of ice flow from land into the ocean has increased the rate of sea level rise by about .06 millimeters (about .002 inches) per year, or roughly 4 percent of the 20th century rate of sea level increase. This version has been updated to include the 2004 calving front as derived from satellite data. Updated print resolution image showing the retreating front over the past 150 years.