|
NORTH CASCADE GLACIER RETREAT
Mauri S. Pelto, Director
Founded
1983
|
|
Terminus Behavior
|
North Cascade glacier retreat is rapid and ubiquitous. All 47 monitored glaciers are currently undergoing a significant retreat or have disappeared in the case of six of them Lyall Glacier, Lewis Glacier, Spider Glacier, Milk Lake Glacier, Mt. David Glacier and North Arm Whitechuck Glacier have disappeared (Right). This retreat on eight Mount Baker glaciers from 1984-2005, each was advancing in 1975, averages 340 m. The data indicate broad regional continuity in glacial response to climate. The rate of retreat increased from 1992-1998 and again in 2003-2006. On each glacier the terminus location is surveyed from a fixed benchmark location beyond the terminus. The terminus is also located utilizing differential GPS to determine location to within a few feet. Glaciers are not just retreating at the terminus, lateral and even retreat at the head of the glacier can also be substantial.
|
 The disconnected small snow patches of the former Spider Glacier in 2007.
|
Glacier Disequilibrium: There is no evidence that North Cascade glaciers are close to equilibrium. Mass balance has continued to decline even as the glaciers have retreated. Their ongoing thinning indicates that all of the glaciers will continue to retreat in the foreseeable future. In cases where the thinning is substantial along the entire length of the glacier, even in the accumulation zone than no point of equilibrium can be achieved with present climate and the glacier is unlikely to survive. This is the case on 9 of 12 glaciers where we have mapped the changes in glacier thickness. Foss Glacier, Mount Hinman and Ice Worm Glacier, Mount Daniels are two examples of endangered glaciers. The primary glaciers of Mount Baker can all retreat to a new point of equilibrium with current climate. Glaciers that will not survive are identified by the retreat of their margins in their upper regions and new rock outcrops in these areas. This is supposed to be the accumulation zone and thinning should not be occurring.
|
Terminus of Lyman Glacier. The lake beyond the glacier began to form in 1940. The terminus has retreated at a rate of 10 m/a since then. The area where vegetation becomes dominant is the 1890 trimline.  .
|
|
At left Honeycomb Glacier in 1977 (Bill Arundell) and 2006
(Lowell Skoog)
|
|
 Columbia Glacier retreat 1984-2006. |
Easton Glacier retreat 1985-2003. |
|
|
 Lower Curtis Glacier retreat 1985-2003. |
Lower Curtis Glacier 1908. (Asahel Curtis
Photograph) |
 This rapid glacier retreat
is evident in the reduced
stream flow and increased runoff in the area. In the long run glacial retreat
causes less runoff to be available which in turn reduces overall water supply.
The recent change in climate is directly effecting the glaciers. The increases
in temperature is causing the retreat of the glaciers to increase at a rate
that is effecting the streamflow and runoff in the area. Data of specific
retreat is shown below. The Lewis Glacier at left melted completely
in 1993
|
The Foss Glacier at left in 2005 with the 1985 margin
illustrated in red. This glacier has lost half of its area in just 20
years, below is Foss Glacier in 1988
|
|
|
Table 2. Retreat in meters of North Cascade glaciers since the LIAM.
|
