October 12, 2012
Apuserajik Glacier Retreat, southeast Greenland
Posted by Mauri Pelto
Anders Anker Bjørk at the Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen alerted me to the retreat of the Apuserajik Glacier (just south of Helheim Glacier), which is not a unique name for a Greenland glacier. Here we examined satellite imagery from 1986, 2000, 2003, 2008 and 2011 to document the retreat, development of a new island and the drainage of a former ice dammed lake. Bjørk et al.(2012)identify the terminus change of 132 glaciers in southeast Greenland over the last 80 years. They observe that the observational period can be divided into three periods. Two recessional events 1933-1943 at the onset of their observations and 2000-2010. There was also a period of widespread advance from 1943 to 1972. In their supplement Table 7 identify the retreat of SEGL017-Apuserajik Glacier from 1933 to 2010. There was a 1.5 km retreat from 1933-1972, a 0.9 km retreat from 1972 to 1985 and a 3.7 km retreat from 1985-2010. The rate from 1933-1985 was 50 m/year, and from 1985-2010 was 140 m/year. The first image is from 2011 and the red terminus line is from 1986, the orange line from 2000, the green line from 2008 and the magenta line from 2011. Below the first image is the sequence in order of 1986, 2000, 2003, 2008 and 2011, the red arrow in each indicates the 1986 terminus and the magenta arrow the new island at the 2011 terminus. The lake that is at the 2008 terminus is quite substantial in 1986 and 2000, by 2003 it has drained considerably and is near its current size, having separated into several pieces. The terminus has retreated 4.2 km from 1986 to 2011, a rate of about 160 m/year. The Apuserajik Glacier was not observed to readvance by Bjørk et al (2012). The retreat here and the change in the characteristics of the lake in a former side valley, is similar to the retreat and opening of a new fjord at Thyrm Glacier. The Helheim Glacier just to the north is a much larger and faster moving glacier that has garnered considerable attention and has retreated 4.8 km from 1985-2010 (Joughin et al 2008; Howat et al, 2005; Andresen et al, 2011))The last image is a closeup of the new islands and the narrower lake entrance. With the new islands being noted by orange and magenta arrows. The yellow arrow indicates a valley that was in 1986 filled by glacier ice and is increasingly bare rock, indicating the upglacier thinning.