October 23, 2014
Austre Okstindbreen Retreat, Norway
Posted by Mauri Pelto
Austre Okstindbreen is the largest glacier of the Okstindan Icecap. It flows north from the 1700 m to a terminus in a proglacial lake at 900 m. The lake drains into Grasvatnet. The glacier had a sustained retreat of 2 km from 1908-1980, emplacing annual moraine ridges during the 1950-1968 period (Worsley and Ward, 1974). The other main glacier of the Oksindan Icecap is Vestisen. Knudsen and Theakstone (1988) identified a series of glacier dammed lake draining events from 1976-1987, with glacier retreat this is no longer occurring. Jacobsen et al (1997) noted that the lower glacier in particular had slowed down from 1976 to 1995. They also reported during a series of positive balance years the ELA averaged 1250 m. The Norwegian Water Resources and Energy Directorate (NVE) reports annual terminus of this glacier, noting a 118 m retreat from 2010-2013. Here we examine changes in the glacier from 1994-2014 using Landsat imagery.
Google Earth Image
In 1994 the glacier terminates at the red arrow, the snowline (purple dots) is at 1300 m. The width of the glacier at the eastward turn, yellow arrow is 1500 m. In 1999 the glacier has retreated a short distance and the snowline is at 1400 m. In 2006 the proglacial lake has continued to expand. The glacier width at the east turn is 1300 m. The snowline is at 1450 m. In 2014 the snowline is at 1550 m. The glacier width at the yellow arrow is down to 1100 m. The retreat from the red arrow is 400 m, which is 20 meters/year. The persistent high snowline above 1300 m in images that are not even at the end of the melt season indicate a significant rise. The 400 m reduction in the width of the glacier at the east turn, which is 1.5 km above the terminus, indicate the retreat will continue. The glacier retreat parallels that of Norway glaciers in general since 2000, with 23 of 24 glaciers examined consistently by (NVE) retreating during this interval, one was close to equilibrium. Engabreen, Tunsbergdalsbreen and Blamannsisen.
1999 Landsat image
2006 Landsat image
2014 Early September Landsat image
2014 Mid-September Landsat image