Continental Glacier, Wyoming Fragmentation Accelerates

On November 17, 2023April 18, 2024 By mspeltoIn Uncategorized, Wind river range1 Comment

Continental Glacier in 1994 Google Earth and 2016 and 2022 Sentinel images, illustrating the separation at the black arrows, into the northern middle and southern parts, with an impending separation at green arrow.

Continental Glacier is a long plateau glacier draped along the continental divide in the Wind River Range, Wyoming. It drains into Torrey Creek and then the Wind River. In 1994 this glacier extended 5 km from south to north with an area of 2.4 km². In 2012 Van Looy et al (2013) used GPR to determine ice thickness and project how long the glacier could last. They found 59% of the glacier was less than 40 m thick, with two cirque depressions filled with deeper ice exceeding 150 m. They found a thinning rate of 0.3 m/year for the 1966-2012 period. They did not include the southern part of the glacier in their study.

In 2016 the glacier is in three parts and glacier area has been reduced to 1.9 km². By 2022 additional fragmentation at the green arrow in the middle segment is imminent. The northern and southern parts are wasting away rapidly. A closeup of the northern section of the glacier in 2022 illustrates how thin, fragmented, and stagnant the ice has become. Point A-E indicate bedrock areas emerging amidst northern part. Point F-I indicate very thin, old, dark ice in the middle part. This glacier is following a similar path to the Grasshopper Glacier just to the south. Van Looy et al (2013) noted that in the next century the volume would be reduced by 43% and the glacier would be lost in 300-400 years. The pace of loss has increased significantly with volume loss of ~2% per year since 2013, which will lead to loss of all areas with less than 40 m of ice in 2012 being lost by 2040. The two areas of deep ice will persist much longer. This same trend has led to the loss of Heap Steep Glacier, Harrower Glacier and Twins Glacier in the Wind River Range since 2015.

Continental Glacier in 9-4-2022 false colar Sentinel image. Point A-E are bare rock areas amidst northern part of glacier. Point F-I dark, old thin ice in the middle part.

Sacagawea Glacier, Wyoming is Disappearing

On June 2, 2014 By mspeltoIn Glacier Observations2 Comments

Sacagawea Glacier in the Wind River Range of Wyoming lost 35% of its area between 1966 and 2006. This glacier on the west slope of Sacagawea Peak and Helen Peak and just north of Upper Fremont Glacier. Here we compare Google Earth imagery of the glacier that indicates the change during this forty year period. In 1966 the glacier had an area of square kilometers. The first image is the USGS map of the glacier from 1966 imagery. The orange outline is the glacier margin at this time and the red outline the 2006 glacier boundary. By 1994 Google Earth images indicate a retreat of 270 m along its main terminus. A small lake has also begun to form along the southern section of the terminus. The northern section of the glacier below Helen Peak had by 1994 become practically disconnected from the main section of the glacier. In 1994 the exposed blue ice area is extensive, indicating that most of the glacier was consistently losing its snowcover. With retained snowcover limited to the steeper slopes above 3700 m. By 2006 the lake was 400 m long and 150 wide along the southern section of the terminus. The terminus retreat along the main terminus averaged 350 m since 1966. The northern section of the glacier is fully detached from the rest of the glacier. The fraction of snowcovered area is 10% in 2006, which was typical for the 2003-2006 period. This is insufficient to maintain a glacier, the snowcovered area for temperate alpine glaciers such as the Sacagawea that lacks extensive avalanching is 55-65 % snowcover at the end of the melt season. The locations marked with Point A in red are locations where rock formerly beneath the glacier has been exposed as the glacier melted from that location. By 2013 a Landsat image of the glacier indicates that the glacier is beginning to recede from the terminus lake, further that there is almost no retained snowcover in 2013 and that the glacier is separated into three segments note the yellow arrows. The upper margin of the glacier is receding which indicates thinning in the accumulation zone, an indicator that this glacier does not have a significant accumulation zone and cannot survive current climate (Pelto, 2010). In a Planet Action Project Pelto (2010)reported that 2/3 of the 15 Wind River glaciers examined were not going to survive current climate. This includes Minor Glacier, Sourdough Glacier, Grasshopper Glacier and Lower Fremont Glacier.
1966 USGS map

1994 Google Earth

2006 Google Earth

2013 Landsat Image

Analysis of Sacagawea Glacier and Upper Fremont Glacier, Wind River Range, Wyoming

Grasshopper Glacier Wyoming disappearing

On June 13, 2010June 17, 2011 By mspeltoIn Glacier Observations

Grasshopper Glacier in the Wind River Range of Wyoming has a southern terminus calving into a lake , sometimes referred to as Klondike Glacier, and a northern terminus. The southern terminus is calving and retreating expanding the unnamed lake it terminates in. The southern glacier has retreated 350 m since 1966. This lakes drains north under the glacier and down the valley under the Grasshopper Glacier. This is quite unusual to have a stream draining under the glacier from a lake at a terminus of the glacier. The lake can drain to the east if it rises to the 12,000 foot threshold. This was the case in 1994. The terminus area is not being fed by the upper accumulation zone to the northwest any longer. The terminus is stagnant and will continue to melt away. The lake has existed since at least 1950. In 2003 it drained substantially and quickly below the glacier causing a downstream flood. An ice dam break released a glacier flood is a jokulhaup. The lake was reported by the USGS to have drained 90%. In the 2006 image it has largely refilled, but notenough to drain to the east again. It is likely given the stagnant nature of the glacier, that the drainage conduit will not be fully closed, and the lake can drain through the channel on more of an ongoing basis. The northern terminus has retreated 730 m the most extensive retreat in the Wind River Range. The main accumulation area on the west side of the glacier has become segmented by large bare rock areas as noted by comparing the 1966 map and 2006 image. The 1966 boundary indicated in orange noted area circled in burgundy in the second image below. The combined retreat of the two terminus is over one kilometer this is 40 % of its 1966 length of 2.4 km. The significant thinning and marginal retreat at the head of the glacier is symptomatic of a glacier that will disappear with current climate. The glacier seldom has significant snowcover at the end of the melt season is with the current climate will melt away. In 2009 the glacier did have significant snowcover at the end of the melt season for only the third time in the last 10 years.