Sittankanay Glacier drains the north side of the small icefield that feeds the retreating Wright, Speel and West Speel Glacier. The 10 km long glacier is the headwaters of the Sittkanay River, a tributary to the Taku River. Here we utilize Landsat images from 1984-2013 to identify the recent changes in the glacier. The glacier begins at 2000 m and ends in a lake at 250 m, the terminus has heavy debris cover, which is unusual for this area. The Canadian Topographic map indicates a lake that is 400 m long.
Canada Topographic map
Google Earth Image
In 1984 the terminus of the glacier, red arrow is at the base of a steep gulch, yellow arrow marks the 2013 terminus. The lake has expanded to 600 m in length. The purple dots indicate the snowline is at 1500 m, which leaves limited snowpack for sustaining the glacier. In 1996 and 1999 the snowline was also at 1500 m, indicating negative mass balances that underlie the retreat. By 2013 the glacier the lake had expanded to 1700 m in length. The glacier has retreated 1100 m since 1984. The snowline is at 1400 m in the mid-August image, and will rise above 1500 m by the end of the melt season. A close up view of the terminus indicates the heavy debris cover has large uncrevassed sections that appear nearly stagnant, pink arrows. There is one feature in the 2006 Google Earth image that is 1.0 km from the terminus, a circular depression-red arrow, with concentric crevasses that indicates a subglacial lake that partially buoys the glacier. This also indicates that rapid retreat will continue. The retreat is enhanced by calving, but it is the insufficient size of the accumulation zone that is driving the retreat of this glacier and its neighbors.
1984 Landsat image
1996 Landsat image
1999 Landsat image
2013 Landsat image
Google Earth image
Boulder Glacier flows down the west side of Mount Baker a strato volcano in the North Cascades of Washington. This steep glacier responds quickly to climate change and after retreating more than 2 kilometers from its Little Ice Age Maximum, it began to advance in the 1950’s as observed by William Long. The glacier advance had ceased by 1979. From 1988-2008 we (NCGCP) have visited this glacier at least every five years recording its changes. In 1988 the glacier had retreated only 25 meters from its furthest advance of the 1950-1979 period. By 1993 the glacier had retreated 100 m from this position. At this time the lower 500 meters of the glacier was clearly stagnant. By 2003 the glacier had retreated an additional 300 m. In 2008 the glacier had retreated 490 meters from its 1980 advance position, a rate of 16 meters per year. The glacier as seen in 2008 despite the steep slope has few crevasses in the debris covered lower 400 meters of the glacier. This indicates this section of the glacier is stagnant and will continue to melt away. The transition to active ice in at the base of the icefall on the right-north side of the glacier. Below is the glacier in 1993 note the darkened cliff at adjacent to and right of the terminus. The picture below that is from 1998 again note cliff, than in 2003 from the same location as the 1993. Than an image from 2008 of the terminus from further upvalley, as it is not clearly in view from the previous location. And a picture from Asahel Curtis taken in 1908. This glacier after 25 years of retreat is still not approaching equilibrium and will continue to retreat. This is a reflection of continued negative mass balance as measured on the adjacent Easton Glacier. It does respond fast to climate change, and the climate has not been good for this glacier. The glacier does have a consistent accumulation zone and can survive current climate.Picture from August, 1993 of the terminus of Boulder Glacier Picture from August 1998 of the terminus of Boulder GlacierPicture from August 2003 of the terminus of Boulder Glacier.Boulder Glacier in August 2008. Boulder Glacier in 1908 viewed across the glacier at the present terminus location during a Mountaineers trip taken by Asahel Curtis. A satellite image from 2009 (green=2009, brown=2006, purple=1993 yellow=1984), shows additional retreat now at 515 meters from 1984 to 2009, 20 meters per year. An examination of the same view of the terminus in 1993 and 2009 indicates the extent of the retreat and the reduction in crevassing below the icefall. (
For 30 years the North Cascade Glacier Climate Project has focused on observing the response of glaciers to climate change.
The Yakutat Glacier during the 1894-1895 Alaskan Boundary Survey ended near a terminal moraine on a flat coastal outwash plain. By 1906 the glacier had retreated from the moraine and a new lake was forming. Harlequin Lake. Surveys of the terminus of the glacier indicated a retreat of 1 kilometer in that decade. From 1906-1948 the glacier retreated an additional 5 km. From 1948-1958 the glacier retreated 3.6 km. The retreat is evident in comparing the Yakutat B-3 quadrangle, from 1958 photography, and Landsat imagery from 1984, 2010 and 2013. Points A-D are the same in each image and the yellow dots are the terminus. In 1984 the terminus was just retreating from a peninsula marked A, the valley at D was filled with ice, there was no break in the surface at C and B was well inland of the terminus. By 2010 the glacier had retreated from A, the valley at D was deglaciated, a small strip of bedrock-sediment was exposed at C from what had been beneath the glacier, and B was still well inland of the terminus. By 2013 the northern arm of the glacier had retreated 6.4 km from the peninsula at A toward the peninsula at B. The central arm of the glacier toward C had retreated 7.5 km and the retreat on the southern edge of the glacier was 6.5 km. The glacier had retreated on average more than 6.6 km in 30 years, a rate of 220 m/year. The retreat was most rapid from 2010-2013, when the glacier retreated 3 km.
Yakutat terminus map
1987 Landsat image
2010 Landsat image
2013 Landsat image.
Today the glacier is the focus of a study by the University of Alaska, led my Roman Motyka, Martin Truffer and Chris Larsen
They have set up a time lapse camera to record frontal changes. The goal is to understand the controls on calving into Harlequin Lake of this glacier. More amazing than the retreat has been the observed thinning of the glacier. The glacier has thinned by more 200 m on average according to the preliminary thickness change maps from the UAF project (Truessel et al 2013). The Yakutat Glacier does not have a high accumulation zone and the recent increase in the snowline elevation and thinning of the glacier have led to a substantial shrinking of the accumulation zone and thinning of the glacier in the accumulation (Truessel et al 2013). This glacier does not have a persistent significant accumulation zone and cannot survive (Pelto, 2010). For a calving glacier to be in equilibrium it needs to have at least 60 % of its area snowcovered at the end of the summer. The glacier is in the midst of a large ongoing retreat. The retreat rate and calving mechanism is similar to that of Grand Plateau Glacier, Bear Lake Glacier and Gilkey Glacier. However, unlike these Yakutat Glacier lacks an accumulation zone, a better analog is East Novatak Glacier, which also has a lower elevation accumulation zone.
Zemu Glacier is a 26 km long glacier draining the east side of Kanchenjunga the world’s third highest mountain. The importance of the glacier is that it is a key water source for the Teetsa River. The glacier acts as a natural reservoir releasing water due to melting. The Teetsa River is the focus of a hydropower development project being undertaken by the Government of Sikkim. To date 510 mw of the proposed 3500 mw potential are operating. This is a run of the river project, with the water extracted from the river without a dam, run along the valley wall and dropped back to the river through a series of turbines. Run of river is much less expensive than a dam in this remote, earthquake prone, mountainous valley. Zemu Glacier has received little attention, and hence we will have to rely on Digital Globe imagery to observe its changes. The glacier has been observed to retreat at 27 m per year from 1967-1984. Given the length of the glacier the retreat was fairly slow. The glacier has a heavy debris cover on most of its length, insulating it from ablation, and leading to know detectable retreat of the main terminus from 2000 to 2013 Basnett et al (2013). A view of the lower glacier indicates this heavy debris cover, with some scattered small glacial lakes on its surface.
The newly devegetated zone beyond retreating glaciers is small, indicating the slow retreat. Thinning has been significant. The lateral moraine ridges on either side of the main glacier average 150 feet above the main glacier surface. These were built during the Little Ice Age advance. Lateral moraines do not reach above the glacier surface that built them. Thus, the lower glacier has thinned by approximately 150 feet in the last century or so.
A view of a portion of the upper glacier indicates one issue for the glacier. Several of the tributaries no longer join the Zemu, depriving it of a portion of a portion of its former accumulation sources. Near the head of the glacier the walls of Kanchenjunga delivers the debris and large amounts of snow in the form of avalanches to the glacier basin at 5900 to 5200 m. The lower 18 km of the glacier is in the ablation zone where melt dominates. A comparison of 2000 and 2013 Landsat images indicates the lack of change in location of main terminus, red arrows, but recession of surrounding glaciers in the Zemu Basin, yellow arrows.
This area from 5200 m to the 4200 m terminus would quickly melt away without the natural debris cover. The glacier receives considerable snow input from up to 8000 m via avalanches, which are deposited in this region between 5200 m and 5900 m. This glacier will continue to be a large water source for the Teetsa River for the foreseeable future. The glacier has not been retreating as fast or developing a proglacial lake as has happened to Southh Lhonak Glacier, Middle Lhonak Glacier and Changsang Glacier to the north, this should be anticipated in the near future.