March 1, 2019
Skilak Glacier in 1986 and Sept. 2018 Landsat images. In 1986 icebergs and remnant glacier fill nearly the entire lake. The snowline in 1986 is at 1200 m and is at 1300 m in 2018. Red arrow is the 1982 terminus location and yellow arrow is the 2018 terminus location. Point A and C are bedrock outcrops at around 1200 m that have expanded.
Skilak Glacier is an outlet glacier on the northwest side of the Harding Icefield, Kenai Peninsula, Alaska. From 1952-1982 Skilak glacier terminated on a proglacial plain with a broad nearly flat terminal lobe, see map below. The glaciers that drain eastward are in the Kenai Fjords National Park, which has a monitoring program. From 1950-2005 all 27 glaciers in the Kenai Icefield region examined retreated (Giffen et al 2014). Giffen et al (2014) observed that retreated 1,800 m from from 1986-2000, with no retreat from 2000-2005. Here we examine Landsat imagery from 1986-2018 to illustrate the retreat of this glacier, recent snowline elevation and other upglacier changes. The glacier supplies meltwater to Skilak Lake which is a critical salmon habitat for the Kenai. Chinook Salmon spawn on a section of the Kenai River between Kenai Lake and Skilak Lake. With Skilak Lake being the resulting home for ninety percent of the salmon fry for the Kenai River, and with the most of any nursery in the Cook Inlet area. Escapements of chinook in the Kenai River exceed 50,000 annually in two runs (Heard et al 2007). Sockeye salmon is the largest run in the river with over 1,000,000 annual in the Kenai River run (Schoen et al, 2017).
In the 1958 USGS map from there is no lake evident at the terminus of the glacier. The lower 2 km of the glacier is nearly flat. By 1986 the flat terminus was breaking up with icebergs filling the lake. By 2002 the glacier had retreated 4 km generating a lake with an area of 6.2 square kilometers. The snowline in 2002 was at 1200 m. The glacier retreated 300 m from 2002 to 2018. From July 2018 to Sept. 2018 the snowline rose from 1050 m to 1300 m. Though retreat has been slow since 2002 upglacier thinning has been substantial At Point A and C from 1986 to 2018 and at Point A and B from 2002-2018. This will drive additional retreat. The retreat rate should be more in line with that of the neighboring Harris Glacier.
Skilak Glacier 1958 Map prior to lake formation.
Skilak Glacier in 2002 and July 2018 Landsat images. In 2002 is at 1100 m and is at 1150 m in July 2018. Red arrow is the 1982 terminus location and yellow arrow is the 2018 terminus location. The orange arrow indicates indicated banded snow formation. Point A and B are bedrock outcrops at around 1200 m that have expanded.