A Glacier that did not Survive by Mauri Pelto

January 2, 2014 9:08 pm0 comments
Professor Mauri Pelto

Mauri Pelto

The rain had poured down us all day, finally at 4 pm it relented.  We left the tent with a rush and headed over the ridge from Pumice Creek to visit Milk Lake Glacier.  To our surprise the glacier pictured on the map was nearly gone.  It was August, 9th 1994 and we preceded to measure the area of the newly glacier ice free Milk Lake.  In 1979 the USGS map shows a small fringing lake with the main basin occupied by a cirque glacier, Milk Lake Glacier. This extent is evident in the 1962  USGS  aerial photograph, with ice filling most of the basin.  By 1988 in my first visit to the glacier, the glacier had begun to break up in the lake basin, but still the lake was largely filled with ice bergs and fringing glacier.  In 1994 the lake was ice free but the slopes on the west side of the lake still had glacier ice on them, lake area was 0.15 square kilometers.  By 2009 the slopes around the lake were also bare, not even a small remnant of Milk Lake Glacier remained.  What dooms a glacier is the lack of an accumulation zone (Pelto, 2010).  This is the area of a glacier where snow persists year round, it is like the income for your bank account.  Without a net income anywhere on the glacier, there are areas with net ablation (melting), hence these expenditures pay down the glacier ice bank account, until the glacier is lost.  This is a disequilibrium response to new climate conditions.  Unfortunately I have seen the same story play out on many glaciers in the United States.

milk lake 1979

USGS Map Of Milk Lake Glacier.

milk lake glacier 1962

1962 image of Milk Lake Glacier taken by Austin Post (USGS)

donated to North Cascade Glacier Climate Project

milklakeglacier

1988 and 2009 image of Milk Lake expansion.

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