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, averaged 340 m.   The data indicate broad regional continuity in glacial response to climate.    The rate of retreat increased from 1992-1998, 2003-2006 and 2014-2017.  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.

Above former Lyall glacier from Google Earth Image of 2005.

At left Honeycomb Glacier in 1977 (Bill Arundell) and  2006 (Lowell Skoog)

Columbia Glacier retreat 1984-2006.
Easton Glacier retreat 1985-2003.
Boulder Glacier 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.

Different glaciers respond at various rates depending on their characteristics. This is evident in the differing behavior during this century.  With three different glacier types.1) Retreat from the Little Ice Age (LIA) to approximately 1950 followed by a period of advance from 1950-1976, and then retreat since 1976. 2) Rapid retreat from the LIA to approximately 1950, slow retreat or equilibrium from 1950-1976, and moderate to rapid retreat since 1976.  3) Continuous retreat from the LIA to the present.   These types reflect different physical characteristics.  Regardless of type all glaciers are now retreating.

A glacier that illustrates the glacier retreat is the Lynch Glacier below which initially fills the lake basin in 1978, then retreats to the margin of the lake in 1985 and then retreats upslope from the lake by 2007.

Other glaciers have fared even worse Whitechuck Glacier in  particular has suffered, with the north half of the glacier completely melting away (see Death of a glacier).  Variations in other specific glaciers are seen in the Changes in glaciers through time photographic series.

Left, Lynch Glacier in 1978 when it still filled Pea Soup Lake.  Above, Lynch Glacier in 2007

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


TYPE 1 1850-1950 1950-1979 1980-2006 Latitude Longitude
Mazama -2350 450 460 48 48 121 48
Rainbow -1370 512 -410 48 48 121 46
Easton -2420 608 275 48 45 121 50
Squak -2500 305 265 48 45 121 49
Talum -1975 275 -290 48 45 121 48
Boulder -2560 743 -475 48 46 121 47
Coleman -2500 756 -440 48 48 121 50
Deming -2200 628 -350 48 45 121 51
Ermine -1800 170 -330 48 09 121 07
Dusty -1800 280 -350 48 07 121 06
N. Guardian -1550 160 -17 5 48 07 121 05
Kennedy -1700 330 -350 48 07 121 07
Scimitar -1600 350 -320 48 08 121 07
Ptarmigan -1050 75 -190 48 09 121 08
Vista -1900 105 -160 48 09 121 07
Quien Sabe -1250 55 -156 48 30 121 03
Lower Curtis -645 225 -184 48 50 121 37
Ladder Creek -1230 105 -165 48 39 121 09
Sulphide -1775 210 -135 48 49 121 07
TYPE 2          
Cache Col -360 -25 -72 48 22 121 03
Columbia -560 -15 -90 47 56 121 21
Watson -320 -21 -102 48 41 121 06
Neve -720 -25 -330 48 38 121 07
Sahale -260 -12 -62 48 49 121 02
Sholes -1170 -57 -85 48 49 121 46
Yawning -310 35 -75 48 27 121 02
Lynch -60 -390 -123 47 34 121 11
Ice Worm -925 0 -38 47 34 121 10
Daniels -960 -20 -410 47 34 121 10
White River -780 -140 -185 48 03 121 05
Suiattle -2400 15 -175 48 04 121 05
TYPE 3          
Lewis -65 -80 Gone          48 31        120 48 
Colonial -230 -81 -145 48 40 121 08
Lyman -1020 -408 -76 48 10 120 54
Foss -975 -86 -402 47 34 121 12
Hinman -410 -300 -243 47 35 121 14
S. Cascade -1800 -350 -160 48 21 121 03
White Chuck -1300 -330 -230 48 04 121 07
Honeycomb -1750 -290 -430 48 04 121 04
Milk Lake -400 -190 Gone 48 10 121 11
Lyall -370 -60 Gone

 Table 2.  Retreat in meters of North Cascade glaciers since the LIAM.

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