Devon Ice Cap

Two recent papers have examined the changes in flow, mass balance and volume of the Devon Ice Cap(Shepherd et al., 2007) (Dowdeswell, 2004). The Devon Ice Cap on Devon Island in the Canadian Arctic ice cap’s area has an area of 14,000 km2, with a volume of 3980 km3 . The ice cap area decreased by 332 km2 (2.4%) between 1960 and 2000.devon ice cap
The mass balance of the glacier has been assessed since 1960, the total mass loss due to surface melting and runoff between has been about 59 km3. Between 1960 and 1999 about 21 km3 of ice was lost from the ice cap by calving of icebergs, contributing 0.21 ± 0.02 mm to global sea level over this time. The long term mean net surface mass balance was 0.13 m from 1960-2000. From 1998-2007 the mean annual balance has been -0.23 m year, a substantial increase. belcher glacier The Belcher Glacier above is the principal outlet glacier calving up to 30% of the total iceberg volume from the ice cap.
Devon Ice Cap’s negative balance has been due to warming and greater ablation, as the upper part of the glacier has seen some increase in accumulation, which has been more than offset by increased melting. dic mbIn this case the mass balance record indicates a dramatic worsening after 1995. It will be interesting to see the ablation results from the summer of 2008, when record melting was noted both in northern Greenland and northern Ellesmere Island. The glacier is not alone in its behavior, the Prince of Wales Icefield has had a negative mass balance over the last forty years of -80 km3, equivalent to a mean-specific mass balance across the ice field of -0.1 m w.e. a-1, contributes 0.20 mm to global eustatic sea level rise (Mair et at., 2008).
Photographs of the fieldwork coordinated by the University of Alberta

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Lyman Glacier a Century of Change-Years Numbered

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