by Jason Box, Melt Factor blog, September 5th, 2012
In terms of ice flow discharge, one of Greenland’s most productive outlets from the inland ice sheet, if not the most productive glacier in the Northern Hemisphere, the Ilulissat glacier (also known as the Jakobshavn glacier) continues to retreat. The net area change at this glacier since late summer 2000 is a loss of 122 sq. km, equivalent with 1.4 x Manhattan Is., retreating effectively 18 km (11.2 miles) in 12 years. In 2012, this glacier front lost an an area of 13 sq. km, measured from August 2011 to August 2012. This year’s area loss is the largest since the 2007-2008 interval. A concern is that this and other major marine terminating glaciers, as they retreat, they accelerate, increasing their global sea level contribution. Indeed, once the ice shelf in front of this glacier disintegrated, by the end of summer 2003, its speed had doubled (Joughin et al., 2004).
Flying over Ilulissat glacier this July, it was stunning to notice how retreat has proceeded upstream into a northern tributary, producing effectively two main calving fronts to this ice sheet outlet. The faster stream from the west off the right side of the photo also remains in retreat. The glacier is based below sea level more than 75 km inland (Thomas et al., 2011).
The Ilulissat glacier is considered the most productive in the Greenland in terms of ice flow discharge into the ocean (see e.g., Rignot & Kanagaratnam, 2006), even the fastest continuously flowing glacier in the world.