Toby Glacier Retreat, Purcell Range, British Columbia

Toby Glacier is in the Purcell Mountains of southern British Columbia, part of the Purcell Wilderness Conservancy Park. Here we examine retreat of this glacier from 1998 to 2014 using Landsat imagery and Google Earth images. The map image indicates the Little Ice Age advance moraine (LIA_on other imagers) at 1960 m, a lower lake (LL)at 2060 m, an upper lake (UL) at 2280 m, the former ELA at a slope change at 2500 m and the recent ELA at 2600-2650 m, all images are oriented with north at the bottom. toby map In the 1998 Landsat image the glacier terminates at the yellow arrow 250 m from the Upper Lake. The snowline in 1998 is at 2650 m and only 25% of the glacier is snowcovered. By 2005 in the Google Earth view from 2005 the glacier terminates 450 m from the Upper Lake. In 2013 the glacier terminates 800 m from the Upper Lake, pink arrow. Yellow arrow marks 1988 terminus for comparison. The snowline is again at 2650 m in 2013 with a month left in the melt season, no more than 20% of the glacier will be snowcovered by the end of the summer. In 2014 on Aug. 18th the snowline is between 2600 and 2650 m with six weeks left in the melt season, purple dots. By the end of the summer little will remain snowcovered. The terminus has retreated additionally from 2013 but not an amount that can be assessed accurately. Typically 60% snowcover is necessary for glacier equilibrium. The result of the substantial negative mass balance that result from the high snowlines and small accumulation zone will be continued retreat. There are significant bedrock areas emerging in the upper portion of the glacier indicating a lack of a persistent accumulation zone indicative of a glacier that cannot survive (Pelto, 2010). A glacier lacking a consistent accumulation zone is experiencing a disequilibrium response to climate and cannot retreat to a point of equilibrium. This is exemplified best in an image from Wildair Photography-image 36. The glacier retreat is like that of Vowell Glacier and Conrad Icefield in the nearby Bugaboos. TOBY GLACIER 1998
1998 Landsat image
2013 Landsat image
toby glacier 2014
2014 Landsat image
toby glacier tiltview
2005 Google Earth view

toby glacier ge
2005 Google Earth view

Bridge Glacier Retreat Acceleration, BC, Canada

Bridge Glacier is an 17 km long outlet glacier of the Lilloet Icefield in British Columbia. The glacier ends in a rapidly expanding glacial lake with 1100 meters of retreat from 2005-2010. This 200+ m per year retreat is a substantial acceleration over the observed retreat rate of 30 m per year from 1981-2005 by Allen and Smith (2007). They examined the dendrolchronology of Holocene advances of the glacier and found up to 2005 a 3.3 kilometer advance from the primary terminal moraine band, with the most extensive advances being early in the Little Ice Age. The glacier currently ends at 1400 m and in 2010 had a late summer snowline of 2000 m. . The glacier terminus in 1970 is shown in map form, and is indicated by a brown line. The 2003 terminus position from a Landsat image, second image, is next with a red line marking the terminus. The normal Google Earth image, third image, is from 2005 and has a green line. An image from Geoeye from August 2010, last image, terminus purple line indicates the rapid acceleration of retreat. Retreat from 1970-2003 was 48 m per year. The retreat from 2003 to 2010 is 1400 meters, 200 m per year. This continued retreat and area loss will lead to glacier runoff decline in summer. This is crucial to the large Bridge River Hydro complex. This complex managed by BC Hydro can produce 490 MW of power. Stahl et al (2008) note in their modeling study of the glacier that ,”The model results revealed that Bridge Glacier is significantly out of equilibrium with the current climate, and even when a continuation of current climate is assumed, the glacier decreases in area by 20% over the next 50 to100 years. This retreat is accompanied by a similar decreasein summer streamflow.” This parallels our findings on the Skykomish River in the North Cascades, Washington Pelto (2008) and Pelto (2011).

Hoboe Glacier retreat, British Columbia

The Hoboe glacier is a distributary tongue of the Llewellyn Glacier draining the Juneau Icefied in Northwest Britsh Columbia. In 1984 I had the opportunity to hike the length of the glacier carrying supplies to the terminus for a master thesis research project of Richard Campbell at the Univ. of Idaho, during the JIRP summer field season. The glacier is 4 km long separating from the Llewellyn Glacier at 3800 feet and ending at approximately 3000 feet. This is our view from the glacier surface notice the evident trimline above the ice surface showing how thick the glacier used to be.This glacier has receded 2200 meters since early visitors to the area mapped its terminus around 1910, and 3900 m from its maximum advance of the Little Ice Age. The Google Earth views below are from 2001 images. The glacier has retreated 450-500 m in the fifty years that the Juneau Icefield Research Program has been examining it. The first view is looking up glacier and the next two looking down glacier. In all three a trimline is evident where vegetation has not had time to develop due to retreat of the last 75 years. The image above is an aerial photograph taken by Don McCully of JIRP. The trimline in the photograph is 75-85 meters above the glacier surface indicating the thinning that has occurred in the last century. Nearly one meter a year due to the recent climate change that has enhanced summer melting and reduced winter snowfall. The Hoboe Glacier is continuing its retreat like all but one of the nineteen outlet glaciers of the Juneau Icefield. Including the Gilkey Glacier and Tulsequah Glacier.