The Brazeau Icefield straddles high peaks southeast of Jasper, Alberta. The northern outlet glaciers drain into Maligne Lake and the southern outlet glaciers drain in to Brazeau Lake and the Brazeau River. The Brazeau River flows into Brazeau Reservoir a 355 MW hydropower facility, before joining the Saskatchewan River. An inventory of glaciers in the Canadian Rockies indicate area loss of 15% from 1985 to 2005 (Bolch et al, 2010). The more famous Columbia Icefield to the west has lost 23 % of its area from 1919-2009 with ice loss at a minimum during the 1970’s (Tennant and Menounos, 2013). Here we examine an unnamed outlet glacier at the southwest corner of the Brazeau Icefield from 1995 to 2014 using Landsat imagery.
In 1995 the glacier terminated at the red arrow and was 1900 m long, orange dots mark the upper boundary. The glacier had limited retained snowpack in 1995. The poor clarity is do to forest fire smoke in the region. In 1998 the proglacial lake where the glacier terminates is much clearer, snowpack is again limited, but more extensive than in 1995. In 2002 retreat is evident as the lake is expanding as the glacier retreats. The glacier still ends in the lake and still has limited snowcover. In 2013 the glacier has retreated completely from the lake and snowcover is again limited. The lack of snowcover is persistent in the satellite images which are typically not from the end of the melt season, hence even more snowcover will be lost. Lack of a significant persistent snowcover area indicates a glacier that will not survive (Pelto, 2010). In 2014 the area experienced considerable forest fires, which leads to poor image clarity. The glacier terminus is now significantly separated from the lake and terminates at the yellow arrow. The distance from the yellow to the red arrow represents a 350-400 m retreat in 20 years. The glacier has lost 20% of its length in this period. This retreat is similar to that of Fraser Glacier and more significant given the small size of the glacier than for Saskcatchewan Glacier
1995 Landsat image
1998 Landsat image
2002 Landsat image
2013 Landsat image
2014 Landsat image
Robson Glacier is the largest glacier on the highest mountain in the Canadian Rockies. The glacier begins at 3200 m and drains northeast from the summit ending in a proglacial lake at 1720 m. The glaciers upper west side has heavy avalanche accumulation from Mount Robson’s upper slopes, note the 1964 photograph from the legendary USGS glacier guru Austin Post. The history of this glacier has been examined using tree rings and lichenometry. Heusser (1954) observed that the glacier reached its Little Ice Age Maximum arond 1780 and had retreated at a rate of 2 m/year from then until 1908 and at a rate of 16 m/year from 1908-1953. The terminus history up to 2006 is summarized in a map from Roger Wheate (UNBC)and Laura Thomson that indicates, a minor retreat of 300 m from 1850 to 1922, a rapid retreat from 1922-1950 of 1200 m, a readvance from 150 to the 1980’s of 300 m and a resumed retreat of 500 m from the 1980s to 2005. Here we examine satellite imagery from 1987-2014 to see more recent changes.
Robson map from Wheate (2012)
Austin Post 1964 Photograph
In each image the red arrow indicates the 1987 terminus position, the yellow arrow the 2013 terminus position and the pink arrow a bedrock step on the east margin of the glacier. In 1987 the proglacial lake at the terminus is 350 m long. The bedrock step on the eastern margin is largely buried under the glacier and the snowline is at 2300 m though the melt season still has six weeks to go. In 1989 the terminus is not quite as wide and the snowline is at 2500 m. By 2002 the glacier has retreated 400 m with the proglacial lake having expanded into a new narrower section. The bedrock bench is more prominent adjacent to the glacier and now extends as a bare rock further into the main glacier. The snowline is at 2400 m. By 2006 the glacier has retreated an additional 100 m and the snowline is at 2500 m. There are two apparent bedrock ribs the upglacier one extends 300 m toward the glacier center from the east margin and the lower rib 150 m. This represents most of the flow from the eastern tributary of the glacier that extends only to 2800 m and has less avalanche contribution. By 2013 the glacier has retreated 700 m since 1987, a rate of 30 m/year. This is a more rapid rate than the retreat observed from 1908-1953.The snowline is just above 2500 m. In 2014 the terminus position is a bit obscured in this September image, the bedrock rib is more prominent than in 2006 and the snowline is again above 2500 m, with three weeks left in the melt season.
It is apparent that a zone of persistent and consistent accumulation remains above 2600 m on Robson Glacier, and that it can survive current climate change. The recent trends of a snowline above 2500 m indicates that retreat will continue in the near future in response to current climate. Both 2013 and 2014 have been warm summers leading to above average melt conditions that should lead to rapid thinning of the lower terminus tongue and rapid retreat in the next several years. Hopefully another satellite image will be obtained to indicate the end of season snowline (ELA). The retreat of the is glacier parallels that of Coleman Glacier just east of Mount Robson, Freshfield Glacier and Columbia Glacier.
1987 Landsat image
1989 Landsat image
2002 Landsat image
2006 Google earth image
2013 Landsat image
2014 Landsat image
Fraser Glacier, Alberta on the southern flank of Bennington Peak in Jasper National Park drains into the Athabasca River not the Fraser River. The glacier was reported in the USGS satellite image atlas as having a length of 3.5 km in the 1970’s. In Canadian Topographic maps the glacier extends for over 3.0 km from 2900 m to 2200 m. Today the glacier is barely half that length. The glacier first separated and then the lower section has now melted away. Here we use Google Earth and Landsat imagery from 1996 to 2014 to identify the changes. Bolch et al (2010) noted that from 1985-200 Alberta Glaciers lost 25% of their area. Tennant et al (2012) noted that from 1919-2006 the glaciers in the central and southern Canadian Rocky Mountains lost 40% of their area. Of the 523 glaciers they observed 17 disappeared and 124 separated, Fraser Glacier falls into the latter category.
In each image Point A indicates the same location which after 2000 a small lake develops, Point B, is the location where the glacier separated into two parts. The red arrow indicates the lower section and the yellow arrow the position of the upper terminus in 2014. In the map the orange outline is the glacier boundary on the map, while the green line is the 2005 boundary.
By 1999 the glacier has separated into two parts, but no lake exists yet at Point A. By 2002 a small lake is developing at Point A and the separation between the upper and lower glacier has increased. By 2005, a Google Earth image indicates the diminishing lower section of the glacier is 300 m long and less than 200 m wide, separated from the upper glacier by 250 m. By 2013 the lower glacier is no longer evident, there could be a small remnant of debris covered ice, but it is essentially gone. The glacier now is just 1.6 km long having lost half its length from the mapped glacier and more than half since the satellite image analysis of the 1980’s. The upper margins of the glacier have changed little and some snowpack has been retained. This suggests that now with the entire glacier in the upper basin above 2400 m, the retreat should slow down,and that the glacier can survive current climate (Pelto, 2010). The retreat of this glacier is similar to Apex Glacier, Petain Glacier, Coleman Glacier and Mangin Glacier. The retreat fits the pattern noted by Tennant et al (2012), further Jiskoot et al (2009) noted that the glaciers of the nearby Chaba-Clemenceau Icefield are experiencing faster retreat rates in recent years. All of this loss in glacier area of course means less glacier runoff, since the area lost is greater than the increased melt rate from the remaining glacier area in Alberta.
2005 Google Earth image
1996 Landsat image
2002 Landsat image
2013 Landsat image
2014 Landsat image
Mangin Glacier and its unnamed neighbor flow down the north slope of Mount Joffre, Alberta and drain into Kananaskis Lake. The glacier like the vast majority in Alberta has been losing area and volume during its retreat. Bolch et al (2010) noted that the glaciers in western Canada had on average lost 11% of their area from 1985 to 2005, 16% on the east slope of the continental divide in the Rocky Mountains of Alberta. A comparison of Landsat imagery from 1994 and 2013, Google Earth imagery from 2005 and the Canadian Topographic map published in 1994, based on early 1990’s aerial photographs. In the map Mangin Glacier was a single ice body that extended for 3.2 km ending in a small lake at 2575 m, sections A-C were all joined, green line is glacier boundary for the map and brown line the 2005 glacier margin. By 1994 section C, yellow arrow, has only a tenuous connection and is clearly going to separate from parts A and B. Further a ridge between A and B is beginning to develop, red arrow. By 2005 in the Google Earth image sections A and B are nearly separated by the expanding ridge and C is fully separated from A and B. By 2013 A and B are fully separated, this image is from mid-August with a month of melting to go. The light blue is snowcover and the darker blue is bare glacier ice. In another month the amount of snowcover will be very small. For example earlier this month on Sholes Glacier in the North Cascades we observed rapid expansion of the blue ice zone from 12, 500 square meters on Aug. 3 to 35,000 square meters on Aug. 9. The retreat of the unnamed glacier labeled D is apparent in the comparison of the 1994 and 2013 images, note the green arrow. This retreat is 300-400 m, with much of the retreat coming after 2005. Mangin Glacier’s retreat from the map based on early 1990’s imagery is 500 m, combined with retreat of the top of the glacier 20% of the glacier length has been lost in the last 20 years. Mangin Glacier has been retreating even on its upper margin, this is indicative of a glacier without a consistent accumulation zone, and a glacier that will not survive(Pelto, 2010). Just southeast is Petain Glacier also retreating. As the glaciers retreat their meltwater that is primarily yielded in late summer when other sources are at a minimum will decline. It is anticipated that during this century glacier contributions to streamflow in Alberta will decline from 1.1 km3 a−1 in the early 2000s to 0.1 km3 a−1 by the end of this century Marshall et al (2011).
Coleman Glacier flows north from the Reef icefield on the northeast flank of Mount Robson. This glacier is 6 km long and has a relatively low slope descending from 2500 m to a terminus just above 2100 meters. Coleman Glacier flows north from the British Columbia, in an inventory of western Canada glaciers Bolch et al (2010) found that from 1985-2005 Alberta glaciers lost 25% of their area and BC glaciers 11% of their area. Marshall et al (2011) examining the impact on streamflow of glacier volume loss, estimate an 80-90% volume loss for Alberta glaciers by 2100 with a commensurate decline in runoff. By the time a glacier has lost more than 20% of its area glacier runoff declines as the reduced area exposed for melting has a larger influence than the increased melt rate per unit area (Pelto, 2011). A comparison of Landsat images from 1991 (top image) and 2009 (middle Image) indicate a retreat of 250 m. Formation of a new lake at the terminus is evident at the burgundy arrow. The third image is from the Google Earth imagery of 2006, the purple line is the 1991 margin, the burgundy line the 2000 margin. The retreat from 1991-2006 is 250 m, with 50 m of further retreat by 2010. A more detailed look at the 2006 Google Earth Imagery illustrates a more detailed story. This glacier in 2006 has an accumulation zone that is too small to support the current glacier size, a glacier needs at least 60% of its area to be snowcovered at summers end, and only 30% is snowcovered. . This is simply not just a bad year either. The number of annual layers exposed at the surface is at least 50, such layers emerge at the surface below the snowline as a glacier thins below the snowline. The annual layers emerging at the surface are marked by dark horizons which indicate the former snow surface of a layer, which collects dust throughout the summer and is dirtier than the bulk of an annual layer. Above the snowline layers are progressively buried by more recent winter layers and below the snowline layers are exhumed as the layers above melt away (second image). The location and number of annual layers indicate that today the accumulation zone is typically fairly close to the 2006 snowline. . The terminus area and lower 1 kilometer of the Coleman Glacier is quite stagnant as indicated by the degree of incision of surface glacier streams, the lack of crevassing and the smooth nature of the debris cover on the western side of the glacier. This section of the glacier is melting away. Glacier streams in an active flowing glacier will exploit any current or fairly recent crevasse feature to drain toward the glacier bottom often through a moulin. The lack of such drainage indicates a lack of movement that generates crevassing. The bottom image is a closeup of the main supraglacial stream with the blue arrows identifying the channel. This glacier is further north than the Columbia Glacier or Apex Glacier but is following the same trend.