June 26, 2009

Lyman Glacier a Century of Change-Years Numbered

Posted by Mauri Pelto

This blog will focus glacier by glacier on the changes that are resulting from climate changes. Each has a unique story, yet there will be a recognizable refrain. Lyman Glacier, North Cascades, Washington retreated 1300 m from 1907 to 2008. Below is the glacier viewed from near Cloudy Pass in 1921 on a Mountaineers expedition and in 2005.

lyman 1921lyman2005

This 76% loss in length has been accompanied by a 88% loss in area and a 91% loss in glacier volume. I first visited the glacier in 1985, and have since been to the glacier on 15 occasions, twice with Bill Long, who first visited the glacier in 1940, measuring its terminus position then. The glacier currently ends in a beautiful expanding glacier lake, with an impressive ice cliff that is 40 meters high, 26 meters above the water. This aids in the retreat as the glacier does calve icebergs occassionally. The rate of retreat is 11 meters per year, for a glacier that is 440 m long, this gives the glacier 40 years at the current retreat rate. The glacier is losing area at a rate of 4% per year, giving it 25 years to survive. Volume loss is between 4 and 5% per year, giving the glacier 20-25 years to survive. By any measure with current climate Lyman Glacier will not survive to 2050.   For this glacier the warmer summers since 1977 and the reduced snowpack due to more winter rain events has hastened its decline. The glacier is near a snow measurement station of the US Dept. of Agriculture, which indicates an 18% decline in mean April 1 snowpack since 1945, despite a small rise in precipitation. The glacier is no longer large, but still has considerable thickness, up to 50 m. This particular glacier has not approached equilibrium since the end of the Little Ice Age. Its loss has been hurried along by the recent warming. Even small glaciers take a long time to fully melt away.[url=http://www.youtube.com/watch?v=SiJzgiKReZI]

lyman 2008