April 1, 2012
Langjökull is the second largest icecap in Iceland with an area of 920 square kilometers (Jóhannesson (2009). One of the main outlet glaciers of Langjökull is the Norðurjökull which still reaches Hvítárvatn. Hvítárvatn is a large lake that recieves 70% of its inflow from Langjökull (Flowers et al, 2007). The lake has a maximum depth of 84 m and a surface area of 30 square kilometers. Glaciers in Iceland have begun a ubiquitous retreat since 1995, such as Tungnaarjökull and , Kötlujökull. Figure below is from Jóhannesson (2009). On Langjökull terminus fluctuations are not regularly observed and reported to the World Glacier Monitoring Service (WGMS). The mass balance of Langjökull has been reported to the since 1997, the glacier has lost 16 meters of water equivalent since 1997 (WGMS). This is 8-10% of the volume of the ice cap, and represent the loss of over 1 cubic kilometer of water equivalent per year from the glacier (Guðmundsson et al, 2008). In modelling studies this led Björnsson et al (2006) to project the loss of Langjökull in just over a century. Pope et al (2011) observed that Langjökull has lost an area of 3.4 2.5 km2 yr-1 over the decade.
Here we examine the changes in Norðurjökull from Landsat imagery in 1984, 1994, 2006 and 2009 and Google Earth imagery from 2005. The images are shown in chronologic order below. From 1984 (red line) to 1994 (yellow line) there was a minor advance of less than 100 meters and the glacier front in the lake remained 1.4 km wide. From 1994 to 2005/2006 (green line) the glacier retreated 350 meters, and by 2009 the retreat had reached 450 meters (orange line). This represents a retreat of 30 meters/year. In 2009 the glacier front has narrowed where it meets the lake to 600 meters.