Columbia Glacier, Alberta O km Retreat 1986-2015

Comparison of Columbia Glacier, which is the glacier flowing into the lake at prime in 1986 and 2015 Landsat photographs. The purple arrow is the 1986 terminus, yellow arrow the 2015 terminus place and purple arrow the tributary.

The Columbia Glacier drains the northwest aspect of Columbia Icefield into the Athabasca River in Alberta. The glacier in 1964 was H.H km lengthy, by 1980 N.H km lengthy and in 2015 S.P km lengthy. The glacier drops quickly from the plateau space over a serious ice fall from 2400-1950 m.

The icefall results in the creation of a collection of ogives in the course of the 1960-1990 interval. Ogives are annual wave bulges that type on the base of an icefall because of differential seasonal movement velocity. Ommaney (2002) famous that the glacier superior over one kilometer from 1966 to 1980 the glacier utterly crammed the massive proglacial lake that now exists.

By 1986 retreat had once more opened the lake. Tennant and Menounos (2013) examined modifications within the Columbia Icefield 1919-2009 and located a imply retreat of 1150 m and imply thinning of forty nine m for glaciers of the icefield. They famous that the quickest price of loss on Columbia Icefield glaciers from 1919-2009 was in the course of the 2000-2009 interval.

In 1986 Landsat imagery the lake is one thousand m lengthy. A 2004 Google Earth picture signifies a step in elevation that’s 500 m from the terminus. Glacier elevation lags the basal elevation change; therefore the top of the lake is between 500 and one thousand m from the 2004 terminus.

By 2015 the lake is 4000 m lengthy indicating a 3000 meter retreat from 1986-2015. The price of retreat has been much less since 2004, 300 m, because the glacier approaches the higher restrict of the lake basin. When the glacier terminus retreats to this step, the lake will not improve retreat by way of calving and retreat charges will diminish. A additional change is famous within the absence of ogives on the base of the icefall. As the icefall has narrowed and slowed the outcome has been a cessation of this course of. The purple arrow signifies a tributary that joined the glacier under the icefall in 1986 that now has a separate terminus.

A 2004 picture of the glacier indicating the ogive band, and step the place the higher restrict of the lake probably happens.

The present terminus continues to be lively with crevassing close to the lively entrance. The snowline in each August 2015 and July 2016 is near 2800 m. A extra detailed take a look at the 2016 mass stability circumstances within the area simply west of the glacier recommend Columbia Glacier had a extra damaging stability than within the Columbia River basin.

With time left within the ablation season the snowline is at too excessive of an elevation to maintain robust stream via the icefall. The retreat is extra in depth than the extra well-known and oft visited glaciers draining east from the icefield Athabasca Glacier and Saskatchewan Glacier.

The above publish is reprinted from Materials offered by American Geophysical Union..