Glaciers, hydropower and climate change in West Greenland

Context

Lake Tasersuaq, a few kilometres downstream of Aqqutikitsoq, feeds the hydropower plant that supplies electricity to Sisimiut, the second-largest town in Greenland. The region sits in a precipitation shadow and is considerably drier than the coast, so glacier meltwater contributes a meaningful fraction of total summer discharge into the reservoir. Understanding how this glacier cluster is changing matters for long-term energy planning.

Aqqutikitsoq (2.85 km², ~27 km northeast of Sisimiut) sits within a cluster of roughly 100 glaciers in the Sisimiut area covering ~85 km². It was chosen as a representative study glacier for this cluster. At the time of the study it was also the first glacier on Greenland's west coast with both a detailed ice thickness survey and a multi-decadal geodetic mass balance record.

Approach

With no drone available, 622 photographs were taken from four mountain peaks flanking the glacier using two consumer cameras, together with 138 GPS-surveyed ground control points. The resulting 2014 SfM DEM (0.73 m native resolution) was differenced against a 1985 DEM derived from aerial photographs to compute surface elevation change. In parallel, 37 ground-penetrating radar (GPR) profiles totalling 18.5 km gave the 2014 ice thickness distribution.

Results

From 1985 to 2014 the glacier lost 49.8 ± 9.4 million m³, roughly a quarter of its 1985 volume, at a mean thinning rate of 0.60 ± 0.11 m/yr. This is comparable to the geodetic mass balance of Swiss Alpine glaciers over a similar period. Total ice volume in 2014 was 148.6 ± 47.7 million m³, with a maximum depth of 174 m. The ice thickness data were later used as one of 18 reference glaciers in the ITMIX global ice thickness model intercomparison exercise.