September 22, 2011
The Apex Glacier is part of the Clemenceau Icefield Group in the Rocky Mountains of British Columbia. The Apex Glacier drains into 430 square kilometer Kinbasket Lake. The lake is impounded by the 5,946 MW Mica Dam operated by BCHydro. In a recent paper Jiskoot et al (2009) examined the behavior of glacier in this and the neigboring Chaba Icefield. They found that from the mid 1980’s to 2001 the Clemenceau Icefield glaciers had lost 42 square kilometers, or 14% of their area. During this same period terminus retreat averaged 21 meters per year on the glaciers. In this post we are looking just at Apex Glacier contrasting the mapped extent, 2001 extent and 2010 extent in a Landsat image. A new glacier lake began to form after the 1980’s mapped extent. In the images below the 1980’s terminus is marked with a green line, the 2001 extent in magenta. By 2001 in the Google Earth image the lake is 0.5 km long, in 2010 the lake is 0.8 km long.
2010 Landsat image Apex Glacier’s retreat of 300 m in nine years exceeds 30 meters per year, red arrow 2010 terminus. Hester Jiskoot’s (University of Lethbridge, Alberta) found a retreat rate of 52 meters per year from 1986-2001. The reduced rate of retreat may result from the lake depth being reduced, that the lake is getting a bit narrower hints at this as well. One other interesting aspect is that this glacier is fed by a northern and a southern accumulation zone. The snowline is 2400 to 2500 meters in the 2010 August Landsat image. The remaining accumulation zone is quite small for the northern accumulation zone with another month of melting to go. The ablation zone is between the purple margin and burgundy snowline. The accumulation zone is between the snowline and the green upper limit of the glacier, with the bare rock areas noted with the tan line. In 2013 the glacier has continued to retreat, though the change of approximately 100 m since 2010. In 2013 the glacier lost all but 10% of its snowcover with the snowline at 2700 m, yellow dots. This represents a large negative mass balance that will reinforce retreat.
The result for Kinbasket Lake of the loss of the collective large area is a reduction in summer glacier melt and summer glacier runoff. The annual runoff which will be dominated by annual precipitation would not change just because of the glacier loss as noted in cases like theSkykomish Basin (Pelto, 2011) and Bridge River (Stahl et al 2008).