Professor of Environmental Science at Nichols College in Massachusetts since 1989. Glaciologist directing the North Cascade Glacier Climate Project since 1984. This project monitors the mass balance and behavior of more glaciers than any other in North America
Drogpa Nagtsang Glacier, China retreat and proglacial expansion in 1993 and 2021 Landsat images. Red arrow is the 1993 terminus, yellow arrow the 2021 terminus and yellow dots are the snowline.
Drogpa Nagtsang Glacier, China is 30 km west of Mount Everest terminating in an expanding proglacial lake. The glacier begins on the Nepal border at 6400 m, and its meltwater enters the Tamakoshi River that supplies the Upper Tamakoshi Hydropower project a 456 MW run of river project that began operation in September 2021. King et al (2017) observed the mass balance of 32 glaciers in the Mount Everest area including Drogpa Nagtsang and found a mean mass balance was -0.7 m/year for lake terminating glaciers. In this basin from 2000–2016, mass balance loss resulted in surface elevation to decline at a rate of −0.63 m a−1, which drove a velocity decline of ~25% (Zhong et al 2021). They also noted that the area of proglacial lakes in glacier contact increased by ~204% . Pelto et al (2021) documented the exceptionally high winter snowline in the Mount Everest region from October 2020-January of 2021. Here we examine changes in Drogpa Nagtsang Glacier since 1993 and the snowline variation from October 2020-November 2021.
In 1993 Drogpa Nagtsang Glacier had a substantial number of coalescing supraglacial ponds on its relatively flat stagnant debris covered terminus. The snowline in 1993 was at ~5450 m. At Point A there is extensive crevassing indicating vigourous flow. At Point B a tributary glacier joins the main glacier. At Point C the glacier is a 1.2 km wide glacier tongue. Quincey et al (2009) observed flow of less than 10 m/a in lower 5 km of glacier in 1996 and peaking at 20-30 m/a 8 km from terminus. By 2015 a 2.7 km long lake has developed (Pelto, 2019). In 2021 the lake has expanded to 3 km long. At Point A there is no longer significant crevassing indicating reduced flow. At Point B the tributary no longer connects to main glacier. At Point C the glacier tongue has lost 30% of its width and debris cover width has expanded. The terminus area remains stagnant and the lake is poised to continue expansion.
Snowline variation from October 2020-November 2021, yellow dots. These are Landsat images except May 2021 is from Sentinel.
In October 2020 the snowline on Drogpa was at 5650-5700 m. By mid-January after the record winter heat wave of 2021 the snowline had risen to 5750-5800 m. In May of 2021 as the summer monsoon began the snowline was below the terminus of the glacier (5000 m). In June the snowline had risen to 5450 m. This is a summer acccumulation type of glacier, which means most of the accumulation snowfall occurs during the summer monsoon above the snowline simultaneous with high melt rates below the snowline. The snowline is close to mean freezing level, which has risen to 5400 m in recent years for the summer monsoon period (Perry et al 2020)The snowline than rises in the post-monsoon period. By October 2020 in the post-monsoon period the snowline had rise to 5600 m. A significant storm in late October lowered the snowline to 5250 m for November 2021. This suggests the snow free start to winter we saw last year will not occur this year.
Seven outlet glaciers of the Queulat glacier complex, Chile in 1987 and 2020 Landsat images. A=Rosselot Glacier and D=Colgante Hanging Glacier are the only ones in 1987 not terminating in a proglacial lake. The other five retreated from a proglacial lake since 1987 and Rosselot Glacier retreat has led to formation of two lakes.
Nevado Queulat, Chile is the centerpiece of the Queulat National Park in the Aysen Region. This massif is host to the Queulat glacier complex, which has a number of outlet glaciers. Rosselot Glacier is the largest glacier and it flows north draining into Lago Rosselot and then the Rio Palena. Colgante Hanging Glacier flows south and is the second largest terminating at the top of a cliff as a hanging terminus creating a spectacular waterfall. Paul and Molg (2014) observed a rapid retreat in general of 25% total area lost from glaciers in the Palena district of northern Patagonia from 1985-2011. Meier et al (2018) note a 48% reduction in glacier area in the Cerro Erasmo and Cerro Hudson region, since 1870 with half of that occurring since 1986. The 3.8 km retreat of Erasmo Glacierfrom 1998 to 2018 is a rate of ~200 m/year. Here we examined the changes from 1987 to 2021 of seven outlet glacier locations around the ice cap.
Seven outlet glaciers of the Queulat glacier complex in Queulat National Park in Chile in 2021 Sentinel 2 image. A=Rosselot Glacier and D=Colgante Hanging Glacier are the only ones in 1987 not terminating in a proglacial lake. The other five retreated from the proglacial lake since 1987 and Rosselot Glacier retreat has led to formation of two lakes.
In 1987 Rosselot (A) terminates against the valley where the valley turns to the east,and there is no lake at the terminus. In 1999 glacier retreat has exposed a new lake that is 900 m across. By 2015 the glacier has retreated south of a second lake that is 700 m across. In 2021 the glacier has retreated 250 m from the edge of the lake terminating at an elevation of 650 m. The total retreat from 1987-2021 has been 2100 m, ~60 m per year. This is the loss of 15% of the entire glacier length.
Seven outlet glaciers of the Queulat glacier complex, Chile in 1999 and 2015 Landsat images.
Outlet Glacier B terminates in a lake at 750 m. In 1999 the glacier has retreated to the top of a steep slope above the lake terminating at 850 m. In 2015 the glacier is terminating at 925 m and is receding up a north-south oriented valley. By 2021 the glacier has retreated 1100 m from the shore of the lake.
Outlet Glacier C terminates in a small fringing proglacial lake. By 1999 the glacier has retreated ~400 m to the base of a steeper slope, there is still ice cored moraine beyond the terminus. By 2015 a 500 m lake has formed beyond the terminus. In 2021 the glacier has retreated ~1000 m since 1987.
Colgante Hanging Glacier (D) terminates at the top of a steep cliff in 1987. The glacier reamins at the top of this cliff up to 2021, with considerable avalanching off the front into the valley below. A reconstituted glacier at the bottom of the cliff is thinning.
Outlet Glacier (E) terminated in a proglacial lake at 700 m elevation in 1987. By 1999 the glacier had a tenuous connection to the lake with a reconstituted stagnant area in contact with the lake. In 2015 the glacier no longer reaches the lake. In 2021 the terminus of the glacier is 400 m from the lake.
Outlet Glacier (F) terminated in a proglacial lake at 750 m elevation in 1987. In 1999 the glacier still connected to the lake. By 2015 the glacier had receded from this lake. In 2021 the glacier has retreated 350 m from the lake and terminates at 1000 m.
Outlet Glacier G is a stagnant debris covered glacier tongue that is in contact with a proglacial lake in 1987 and 1999. By 2015 the glacier has retreated from contact with the lake. In 2021 the glacier has retreated 600 m across an outwash plain from the lake.
Barcaza et al (2017) indicate that Colgante Hanging Glacier did not retreat from 2000-2015, while Rosselot Glacier lost 0.9 km2.
Easton Glacier on Mount Baker in late August 2021, with less than 20% of the glacier retaining snowpack.
The exceptional heat of the summer of 2021 across glaciated mountain ranges of the Pacific Northwest, reduced snowcover extent from Mount Shasta, CA north to Mount Adams and Mount Baker, WA and east to Glacier National Park, MT, Kokanee Glacier, BC and Bonnet Glacier, Alberta. Here we examine late summer images to illustrate the extent of exposed bare ice and firn across glaciers in the region. For a glacier to be in equilibrium requires at least 50% to be in the accumulation zone, snow covered at the end of the summer. At the end of the summer the snowcovered area varied from 0-20% on all of the glaciers reviewed here, the snowcovered area is the accumulation area ratio. Low accumulation area ratios such as this indicate mass loss of at least 2 m w.e. in 2021 on these glaciers. That is the equivalent of losing a 2 m thick slide of ice off the surface of the entire glacier.
When there is a persistent pattern of snowcover loss on the upper part of the glacier this indicates the lack of a consistent accumulation zone indicating the glacier cannot survive (Pelto, 2010). One indicator of this is new bedrock being exposed on the upper glacier as seen on both Easton and Bonnet Glacier here.
As the winter season begins hopefully a La Nina pattern will deliver much needed deep snowpacks.
Sentinel 2 False and True Color images from 8-25-2021. Yellow arrows indicate where glacier is separating and blue arrows the small remanent of 2021 snowpack remaining. This remanent will not last to the end of the melt season.
Jackson and Blackfoot Glacier in early September Sentinel 2 false color images. Point A indicates exposed ice showing annual layers. Point B indicates exposed firn that had been retained through previous summers. The gray color of the firn indicates how dirty it is and that its albedo would enhance melting.
Adams Glacier on Mount Adams in Sentinel 2 True Color image from 8-30-2021. Pink arrows indicate icefall top and bottom. S=summit area, A=Areas where limited pockets of 2021 snowpack has been retained through August.
The upper reaches of Kokanee Glacier to Cond Peak (2800 m) with no retained snow in 2021. Bare ice is exposed on the lower half of the image, and firn, or multi-year snow above. Picture taken during fieldwork by Ben Pelto.
Bonnet Glacier in Sentinel 2 images indicating the emergence of bedrock due to thinning in the former accumulation zone, Point A. Note the lack of retained snowcover in both years with at least a month left in the melt season.
Watercolor painting of Sholes Glacier. The small figure is at the current terminus of the glacier, and the photo that inspired this painting was taken from where the glacier used to end about 35 years prior. By Jill Pelto
Sholes Glacier is on the northeast flank of Mount Baker, WA. We have spent the last 32 years completing detailed measurments on this glacier that has revealed a story of glacier mass balance loss, thinning, retreat, declining area, and a cascade of other consequences impacting other “ologies” beyond the glacier. If you are intrigued by many ologies, the Podcast by Allie Ward will be inspiring as it was to this title.
Sholes Glacier and stream gage station. We have constructed a rating curve for this station, that the Nooksack Indian Tribe maintains (Grah and Beaulieu, 2013).
The climatology of the region has shifted, with one key change being more frequent and intense heat waves. Glaciers and heat waves just are not compatible. Using daily maximum temperatures for the 1981-2021 period for Mount Baker from ERA5 temperature reanalysis, completed by Tom Matthews at Loughborough University, indicates that there have been 83 days where the maximum temperature exceeded 12°C, an average of 2 days/year. In the last five years there have been 22 days exceeding 12°C, over 4 days/year. There have been 16 days during 1981-2021 period when the maximum temperature exceeded 14°C, 75% (12) of these have been in the last five years.
Probing snow depth on Sholes Glacier in 2014, this is completed annually at a fixed network of over 100 locations.
In terms of glaciology the result of the climate shift is that the glacier has lost 25-30% of its volume from 1990-2021. The terminus has retreated 155 m while the area has decreased by 25%. The changes have been most rapid in the last 8 years. The two years of largest mass loss were 2015 and 2021. We measure both melting (ablation) on the glacier and runoff from the glacier. This combination allows determination of the amount of glacier runoff. During 24 heat waves in the region from 2009-2021 mean daily ablation during the heat waves has ranged from 4.5-7.2 cm w.e./day (w.e.=water equivalent). The highest rate of 7.2 cm was during the June 26-July 1, 2021 period.
Sholes Glacier in 2015 exhibiting the darkening of the surface that occurs in high melt years, increasing melt rates. How much black carbon and algae is part of this darkening is the research of Alia Khan (WWU).
For a glacier to be in equilibrium or have a positive mass balance the majority of the glacier must be in the accumulation zone, snow covered at the end of the summer, that is an accumulation are ratio (AAR) greater than 50%. Pelto and Brown (2012)noted that for Mount Baker an AAR of 60% is required for a break even balance for the year. From 2013-2021 the average accumulation area ratio has been 35%. For Sholes Glacier if 50% of the glacier is exposed ice and firn in early August that increases mass loss. The ice and firn for the same weather conditions have a 30-40% higher melt rate than the snowpack. An early season heat wave strips the snow off earlier exposing the darker faster melting glacier surfaces for longer further increasing mass loss, note image above.
Sholes Glacier in 2021. The glacier has retreated 170 m from 1990-2021, the terminus in 1990 is approximately whre the goats are crossing the stream.
Hydrology downstream in Wells Creek and the North Fork Nooksack River is changing in part because of the changes in glacier runoff. Glacier runoff is a major source of streamflow during the summer low-flow season and mitigates both low flow and high water temperatures (Pelto, 2015). This is particularly true during summer heat waves, but this ability has been diminishing in the region (Moore et al 2020) For the last 37 summers we have been in the field monitoring North Cascade glaciers response to climate change including during heat waves (Pelto, 2018). In the last decade we have made synchronous observations of glacier ablation and stream discharge immediately below Sholes Glacier, Mount Baker (Pelto, 2015). This in conjunction with observed daily discharge and temperature data from the USGS stations on the ~6% glaciated North Fork Nooksack River (NFN) and the unglaciated South Fork Nooksack River (SFN), contrasts and quantifies the ameliorating role of glacier runoff on discharge and water temperature during 24 late summer heat wave events.
Measuring discharge below Sholes Glacier in 2016.
Sholes Glacier and ablation measurements on Sholes Glacier indicate daily ablation ranging from 5-6 cm/day, which for the NFN currently yields 9-11 cubic meters/second. This is 40-50% of the August mean discharge of 24 cubic meters/second, despite glaciers only covering 6% of the watershed. In the unglaciated SFN warm weather events generated a mean stream temperature change of +2°C, only 1 event in the NFN generated this rise and the mean was +0.7°C. Durng the June 2021 heatwave from June 21-29 maxium daily stream temperature in SFN warmed 3°C, vs 0.8°C for NFN. This illustrates that a greater proportion of snowmelt, which NFN recieves, has limited the temperature rise. Discharge rose at least 10% in 20 of the 24 events in the NFN with an average increase of 24%. In the SFN all 24 events led to a decreased discharge with an average decrease of 20%. The primary response to these summer heat waes is increased discharge in the heavily glaciated NFN, and increased stream temperature in the unglaciated SFN.
Discharge change during heat waves in South Fork (decreases) and North Fork Nooksack River (increases) above. Below temperature change during heat waves in South Fork (significant rise) and North Fork Nooksack River (small rise).
Glacier runoff is a product of glacier area and melt rate. Overall glacier runoff declines when area reductions exceed, ablation rate increases. This has already occurred in the NFN and now glacier runoff is declining (Pelto, 2015). The measured ablation rate is applied to glaciers across the NFN watershed, providing daily glacier runoff discharge to the North Fork Nooksack River. For the NFN glacier runoff production was equivalent to 34% of the total discharge during the 24 later summer heat wave events. As the glaciers continue to retreat the NFN will have a declining mitigation of heat waves for discharge and temperature and trend towards the the highly sensitive SFN where warm weather leads to declining streamflow and warming temperatures.
Nooksack Falls heavily glacier fed.
Aquatic ecology in glaciated watershed in turn is impacted. Glaciers are important in maintaining sufficient discharge and stream temperature that are critical for salmon in the North Fork Nooksack. Some cold-water trout and salmon species are already constrained by warm water temperatures and additional warming will result in net habitat loss (Isaak et al 2012). In the Fraser River and Thompson River, BC fish community thresholds were obsrved for mean weekly average temperatures of about 12°C and again above 19°C (Parkinson et al 2015). Below 12°C the community were characterized by bull trout and some cold water species, between 12°C and 19°C by salmonids and sculpins and above 19°C by minnows and some cold water salmonids (Parkinson et al 2015). These thresholds indicated small temperature changes can be expected to drive substantial changes in fish communities. During the 24 warm weather events noted in the North Fork only two events exceeded 12°C, while in the South Fork 15 of the events exceeded 19°C. This suggest that both rivers are near a threshold that could alter the fish community.
In the North Fork Nooksack the number of returning chinook is divided into natural and hatchery spawned salmon. The Chum and Coho salmon data for the Nooksack River during the 1999-2013 interval indicate there are two salmon population peaks for each species. The early peak is in 2002 and the second peak occurs in 2010 (Washington Dept. Fish & Wildlife, 2020). Overall numbers have not sustained an increase and remain endangered.
Ice Worm counts as the sunsets, 110 worms per square meter.
The climatology and glaciology has been difficult for ice wormology On the glacier itself ice worm population density surveys conducted annually indicate the density of ice worms has decreased since 2000 and that even 10 m beyond the edge of the glacier on snowpack they do not exist. This combined with the reduction in glacier area indicate population decline of ice worms.
In 2009 we observed the largest goat herd 62 goats (13 kids), some of them seen here below Sholes Glacier.
The climatology has been more favorable in terms of Goatology.We have conducted annual mountain goat surveys in the Ptarmigan Ridge-Sholes Glacier region each years since 1984. Populations stayed steady from 1984-2000, before rising dramatically through 2010. The difficult winters of 2011 and 2012 reduced the population, followed by a recovery up to 2021.
Three year running mean of mountain goat census conducted each summer while we are working on Ptarmigan Ridge, Sholes Glacier and Rainbow Glacier.
Jackson and Blackfoot Glacier in late August and early September Sentinel 2 false color images. Point A indicates exposed ice showing annual layers. Point B indicates exposed firn that had been retained through previous summers. The gray color of the firn indicates how dirty it is and that its albedo would enhance melting. The yellow arrow indicates the one patch of retained snow in 2021 on Blackfoot Glacier with no retained snow on Jackson Glacier.
The exceptional heat of the summer of 2021 across glaciated mountain ranges of the Pacific Northwest, reduced snowcover extent from Mount Shasta, CA north to Mount Baker, WA and west to Kokanee Glacier, BC and Bonnet Glacier, Alberta. In Glacier National Park, Montana retained snowcover by the end of summer in 2021 is the lowest observed on Blackfoot and Jackson Glacier. Snowcover extent in late summer is a good indicator of glacier mass balance, which controls changes in glacier volume/glacier area (Pelto, 2019). Here we examine the percentage of Blackfoot and Jackson Glacier that have a persistent accumulation zone from 1998-2021.
The USGS in Glacier National Park has over the last 15 years maintained an extensive glacier monitoring program including consistent mass balance observations on Sperry Glacier, and repeat mapping of the 37 named glaciers, 25 of which still qualify as glaciers. The repeat mapping indicates the area lost from 1966 to 2015, (USGS, 2017). There is considerable variation between glaciers, some have lost more than 80% of their area and others have lost less than 20% during this 50 year period. Blackfoot Glacier is the second largest glacier in Glacier National Park in Montana. Jackson Glacier the seventh largest. The USGS identified the area of Blackfoot Glacier in 2015 as 1.5 km2, a reduction of 18% from 1966-2015 (USGS, 2017). Jackson Glacier had an area of 0.8 km2, losing 40% of its area from 1966-2015. Extrapolating area loss to determine when a glacier will disappear, is typically not a useful approach. Glaciers that lack a persistent accumulation zone cannot survive current conditions (Pelto, 2010). Other glaciers may have a persistent accumulation even if small that allows them to persist.
In 2005 a year of mass balance loss in the region the retained area of accumulation in late August on Blackfoot Glacier was ~60% and Jackson Glacier ~40%. The retained area of accumulation in mid-August of 2015 was ~60%, on Blackfoot Glacier and Jackson Glacier 30-40%. In September 2019 at the end of the melt season an accumulation area covered 10-15% of Jackson and 20% of Blackfoot, the lowest observed since at least 1998. In early September 2020 as summer ended both glaciers had an accumulation area ratio of ~40%. The higher typical end of. summer snowcover extent on Blackfoot Glacier explains why area loss has been less in recent decades..
The June-August 2021 period was the warmest of the 127 period of record for the Western Montana climate division (NOAA, 2021). The result was that by the end of August 2021 0n Aug. 30 less than 5% of Jackson and ~10% of Blackfoot had retained snowcover. By September 6, 2021 Jackson Glacier had no significant snowcover and Blackfoot Glacier had less than 10% remaining. Both of these are minimum values indicating large mass balance losses for both glaciers in 2021, likely over 2 m as has been observed to the north on Kokanee Glacier, BC and to the west on Easton Glacier, Mount Baker, WA. There is considerable exposed firn on both glaciers, snow that was retained in recent years, indicative that the glacier had been stripped of more snowcover than other years. The gray color of the firn indicates it is dirty, which will enhance melting.
Jackson and Blackfoot Glacier in late early September of 2019 and 2020 Sentinel 2 false color images. Point A indicates areas of retained accumulation. layers. Point F indicates exposed firn that had been retained through previous summers.
Blackfoot Glacier (B) and Jackson (J) Glacier snowpack in 2005 and 2015.
The southwest side of Kokanee Glacier from the ridge with Cond Peak at the Right and Sawtooth Ridge at center.
By Ben Pelto, PhD, UBC Mitacs Elevate Postdoctoral Research Fellow
Since 2013 I have been working on the Kokanee Glacier. Located just outside of Nelson in southeastern British Columbia (BC), the Kokanee Glacier is due north of the Washington-Idaho border. This work began as part of a five-year study of the cryosphere in the Canadian portion of the Columbia River. This project was carried out by the Canadian Columbia River Snow and Glacier Research Network — spearheaded by the Columbia Basin Trust. The glacier research, which included the Kokanee Glacier, was led by my former PhD supervisor at the University of Northern British Columbia Dr. Brian Menounos and myself. At the culmination of the project, we published a technical report, and a plain language summary of that report. When the five-year project officially ended in 2018, I learned of a BC Parks program called Living Labs, which offers funding for climate change research in BC Parks, particularly research which documents change and guides protected area management. With Living Labs funding in 2019-2021, I have kept the annual mass balance trips going — now a continuous nine-year record — and a winter mass balance trip in 2021. In conjunction with this, Brian Menounos has secured continued funding (continued from our 5-year project) from BC Hydro for LiDAR surveys of the glacier every spring and fall. These surveys are carried out by the Airborne Coastal Observatory team from the Hakai Institute.
During the 2021 spring trip, we found that the Kokanee Glacier had an average snow depth of 4.4 meters. Using snow density measurements collected with a snow-corer, we found that the winter balance for 2021 was 1.91 meters water equivalent (m w.e.). This value was lower than the 2013-2020 average of 2.18 m w.e. (Pelto et al. 2019).
Ali Schroeder probing snow depth on the Kokanee Glacier while Joel McBurney and Drew Copeland look on.
Ben Pelto with the snow corer with Tom Hammond and Micah May on Kokanee Glacier. Photo: Jill Pelto
With a below average winter balance, 2021 would need to feature a cool summer. Instead, multiple heat waves occured, with temperature records being broken across the province. Wildfires burned all over BC and the neighboring US states of Washington and Idaho, swamping the region in smoke for weeks on end. Rather than mitigate for a slightly-below-normal snowpack on the Kokanee, summer 2021 took a blow-torch to glaciers across the region.
We hiked into the Kokanee Glacier on September 12, stopping under a boulder to wait out proximal booms of thunder and flashes in the clouds. We got pelted with bursts of both hail and graupel, and soaked in the rain, before gingerly working our way up boulder field and talus that is climbers route up the Keyhole to the Kokanee Glacier. Like the satellite imagery had shown, there was no snow in sight on the glacier — bare ice only. Instead of my usual camp on the snow, we chose a climbers bivy site to set our tent.
Camp in the Keyhole — a total lack of snow forced us to skip camping on-glacier.
The Keyhole route, a challenging scramble with 43 lb packs.
Stepping out onto the glacier, we immediately ran into difficult terrain, crevasse bridges of snow or firn had collapsed, leaving bedroom-width crevasses gaping open, necessitating an exercise in maze navigation. Our first stop was a stake at 2600 m which typically retains snow (50 to 100 cms), but this year had lost 1.6 meters. In fact, two stakes drilled at the site in 2015 and subsequently buried by snow had melted out, demonstrating that all snow/firn from the intervening years had been lost. This observation clued me in to the magnitude of melt to expect this year.
The first stake visited, showing 1.6 m of melt
Exposed layers of firn in a crevasse by the stake, showing 1.5 m-thick annual layers — now being eaten away by melt.
Travel on the glacier was more challenging in spots, but overall faster, as the total lack of snow meant that most crevasse bridges were gone, requiring less probing of crevasse bridges and roped-travel. Later, using a satellite image from the dates of our visit, I mapped the retained snow cover, limited to two tiny patches high on the glacier’s east side. The accumulation area ratio (AAR), or the ratio of snow cover to bare ice/firn was <0.01, meaning that under 1% of the glacier was covered in snow.
The upper reaches of Kokanee Glacier to Cond Peak (2800 m) with no retained snow in 2021. Bare ice is exposed on the lower half of the image, and firn, or multi-year snow above
The brown surface is multi-year firn, exposed by the loss of snow. In a typical year, the snow line would be visible here. The white surface below the brown is bare glacier ice.
Near infrared-Red-Green 30 cm resolution ortho image of Kokanee Glacier from the Hakai Geospatial/ACO team on Sept. 2, 2021. Note how badly crevassed the glacier is, most crevasses are exposed with no retained snow. The white color and mottled appearance over the upper glacier is a skiff of overnight snow just a few centimeters thick that melted off the next day. Also note bare ice patches exposed under formerly perennial snow patches that have shrunk in recent years and now are disappearing.
Visiting the toe of the glacier, our lowest stake indicated just under 5 m of ice melt, double that of 2020. In May, this location had 3 m of snow; the combined melt of snow and ice (loss of winter snow and glacier ice) is termed the summer mass balance, and at this site was -6.2 m w.e., far higher than the usual -4 m w.e. I also noticed that much of the thin ice along the margin of the toe was gone, and a little rock nunatak (rock island) that appeared in 2015 (images below) became a bite out of the glacier rather than a island. We estimated that the toe experienced 60 m of retreat. Over the past 5 years, the Kokanee has lost an average of 16 m in length annually. Expecting to see above average thinning and retreat, I was still startled to see how diminished and thin the toe looked.
2015: a small hole forms in the glacier margin above the toe, Jesse Milner in the foreground
2021: the hole is now a bite out of the glacier with two prominent rock knobs
A week prior to my field visit, the Hakai Institute ACO team flew a LiDAR survey of the Kokanee Glacier as part of their work with Brian Menounos at UNBC. Comparing this year’s glacier surface with that from last year’s survey, Brian found a whopping 2.55 m of thinning. After mapping the glacier facies (ice/firn/snow) to represent on the density of the observed thinning, this equates to a glacier mass balance of -2.16 m w.e., higher than the previous record loss of -1.20 m w.e. in 2015.
LiDAR-derived height change 2020 to 2021 from 1 m resolution DEMs from Brian Menounos and the Hakai Institue ACO team. The black line is the 2021 glacier outline, note the bite out of the glacier above the toe to the NE corner of the glacier. Small red patches off-ice are seasonal snow patches losing mass. Points represent mass balance observation locations.Kokanee Glacier terminus from 2015 to 2021. 140 meters of retreat for 23 m/yr. Data in the GIF are from Hakai Institute and Brian Menounos of UNBC ACO glacier surveys.
Back home, I crunched the numbers from our glaciological observations of mass balance (consisting of 14 ablation stakes this year) and calculated a mass balance of -1.97 m w.e. With Brian, I published a paper in 2019 (Pelto et al. 2019) comparing glaciological (field) and geodetic (LiDAR) mass balance estimates and found them to be similar — if some factors like snow and firn density were carefully considered. The small difference between estimates is likely due to timing (the LiDAR mass balance is from 8/26/2020 to 9/3/2021, while the field mass balance is 9/12/2020 to 9/13/2021), and that there was a skiff of fresh snow (likely 5-10 cms) on the glacier during the 2020 LiDAR survey.
Kokanee 2021 glacier mass balance. Blue dots are observations. The boxplots show the 100 m bins used to estimate glacier-wide mass balance (median line in black, mean dashed grey line). The grey bars depict the area of the glacier for each 100 m elevation-bandSeasonal and annual mass balance for Kokanee Glacier from LiDAR and glaciological measurements for each balance year from 2013 to 2021 with 2σ uncertainties.
In 2017, I visited the Kokanee Glacier to measure it’s ice thickness using ice-penetrating radar. I found that the glacier on average was 43 m thick using my measurements to tune a glacier model. I published these results in the Journal of Glaciology (Pelto et al. 2020). In the five years since that work, the glacier has lost over 4.8 m of total thickness. That equates to a loss of over 11% of its total volume. 2021 alone wasted away 6% of the glacier’s total volume — an eye-watering number for a single year.
Cumulative mass balance for Kokanee Glacier 2013-2021 from both field and LiDAR measurments. LiDAR-derived mass balance began in 2016.
The heat of 2021 was an outlier, but years like 2021 and 2015 take a toll on the glaciers. Currently, glaciers in western North America are losing around 0.75 m of thickness per year (according to my work in the Columbia Basin (Pelto et al. 2019) and work by Brian Menounos for all of western North America (Menounos et al. 2018)). The better years for Kokanee Glacier (2016 mass balance: +0.12 m w.e.) pale in comparison. That meager surplus was lost the very next year (2017).
Herein lies the issue, positive mass balance years in recent decades are not large enough to offset even average years; hot dry summers take years off the lifespan of glaciers across western North America.
Losing 6% of it’s total volume in 2021, the best we can hope for Kokanee Glacier is a few near-neutral or positive mass balance years to cover back up the exposed firn, to keep the glacier albedo from becoming too dark and increasing the rate at which ice can melt.
The southwest side of Kokanee Glacier from the ridge with Cond Peak at the Right and Sawtooth Ridge at center.
Since 2013 I have been working on the Kokanee Glacier. Located just outside of Nelson in southeastern British Columbia (BC), the Kokanee Glacier is due north of the Washington-Idaho border. This work began as part of a five-year study of the cryosphere in the Canadian portion of the Columbia River. This project was carried out by the Canadian Columbia River Snow and Glacier Research Network — spearheaded by the Columbia Basin Trust. The glacier research, which included the Kokanee Glacier, was led by my former PhD supervisor at the University of Northern British Columbia Dr. Brian Menounos and myself. At the culmination of the project, we published a technical report, and a plain language summary of that report. When the five-year project officially ended in 2018, I learned of a BC Parks program called Living Labs, which offers funding for climate change research in BC Parks, particularly research which documents change and guides protected area management. With Living Labs funding in 2019-2021, I have kept the annual mass balance trips going — now a continuous nine-year record — and a winter mass balance trip in 2021. In conjunction with this, Brian Menounos has secured continued funding (continued from our 5-year project) from BC Hydro for LiDAR surveys of the glacier every spring and fall. These surveys are carried out by the Airborne Coastal Observatory team from the Hakai Institute.
During the 2021 spring trip, we found that the Kokanee Glacier had an average snow depth of 4.4 meters. Using snow density measurements collected with a snow-corer, we found that the winter balance for 2021 was 1.91 meters water equivalent (m w.e.). This value was lower than the 2013-2020 average of 2.18 m w.e. (Pelto et al. 2019).
Ali Schroeder probing snow depth on the Kokanee Glacier while Joel McBurney and Drew Copeland look on.
Ben Pelto with the snow corer with Tom Hammond and Micah May on Kokanee Glacier. Photo: Jill Pelto
With a below average winter balance, 2021 would need to feature a cool summer. Instead, multiple heat waves occured, with temperature records being broken across the province. Wildfires burned all over BC and the neighboring US states of Washington and Idaho, swamping the region in smoke for weeks on end. Rather than mitigate for a slightly-below-normal snowpack on the Kokanee, summer 2021 took a blow-torch to glaciers across the region.
We hiked into the Kokanee Glacier on September 12, stopping under a boulder to wait out proximal booms of thunder and flashes in the clouds. We got pelted with bursts of both hail and graupel, and soaked in the rain, before gingerly working our way up boulder field and talus that is climbers route up the Keyhole to the Kokanee Glacier. Like the satellite imagery had shown, there was no snow in sight on the glacier — bare ice only. Instead of my usual camp on the snow, we chose a climbers bivy site to set our tent.
Camp in the Keyhole — a total lack of snow forced us to skip camping on-glacier.
The Keyhole route, a challenging scramble with 43 lb packs.
Stepping out onto the glacier, we immediately ran into difficult terrain, crevasse bridges of snow or firn had collapsed, leaving bedroom-width crevasses gaping open, necessitating an exercise in maze navigation. Our first stop was a stake at 2600 m which typically retains snow (50 to 100 cms), but this year had lost 1.6 meters. In fact, two stakes drilled at the site in 2015 and subsequently buried by snow had melted out, demonstrating that all snow/firn from the intervening years had been lost. This one observation clued me in to the magnitude of melt to expect this year.
The first stake visited, showing 1.6 m of melt
Exposed layers of firn in a crevasse by the stake, showing 1.5 m-thick annual layers — now being eaten away by melt.
Travel on the glacier was more challenging in spots, but overall faster, as the total lack of snow meant that most crevasse bridges were gone, requiring less probing of crevasse bridges and roped-travel. Later, using a satellite image from the dates of our visit, I mapped the retained snow cover, limited to two tiny patches high on the glacier’s east side. The accumulation area ratio (AAR), or the ratio of snow cover to bare ice/firn was <0.01, meaning that under 1% of the glacier was covered in snow.
The upper reaches of Kokanee Glacier to Cond Peak (2800 m) with no retained snow in 2021. Bare ice is exposed on the lower half of the image, and firn, or multi-year snow above
The brown surface is multi-year firn, exposed by the loss of snow. In a typical year, the snow line would be visible here. The white surface below the brown is bare glacier ice.
Visiting the toe of the glacier, our lowest stake indicated just under 5 m of ice melt, double that of 2020. In May, this location had 3 m of snow; the combined melt of snow and ice (loss of winter snow and glacier ice) is termed the summer mass balance, and at this site was -6.2 m w.e., far higher than the usual -4 m w.e. I also noticed that much of the thin ice along the margin of the toe was gone, and a little rock nunatak (rock island) that appeared in 2015 (images below) became a bite out of the glacier rather than a island. We estimated that the toe experienced 60 m of retreat. Over the past 5 years, the Kokanee has lost an average of 16 m in length annually. Expecting to see above average thinning and retreat, I was still startled to see how diminished and thin the toe looked.
2015: a small hole forms in the glacier margin above the toe, Jesse Milner in the foreground
2021: the hole is now a bite out of the glacier with two prominent rock knobs
A week prior to my field visit, the Hakai Institute ACO team flew a LiDAR survey of the Kokanee Glacier as part of their work with Brian Menounos at UNBC. Comparing this year’s glacier surface with that from last year’s survey, Brian found a whopping 2.55 m of thinning. After mapping the glacier facies (ice/firn/snow) to represent on the density of the observed thinning, this equates to a glacier mass balance of -2.16 m w.e., higher than the previous record loss of -1.20 m w.e. in 2015.
LiDAR-derived height change 2020 to 2021 from 1 m resolution DEMs from Brian Menounos and the Hakai Institue ACO team. The black line is the 2021 glacier outline, note the bite out of the glacier above the toe to the NE corner of the glacier. Small red patches off-ice are seasonal snow patches losing mass. Points represent mass balance observation locations.
Back home, I crunched the numbers from our glaciological observations of mass balance (consisting of 14 ablation stakes this year) and calculated a mass balance of -1.97 m w.e. With Brian, I published a paper in 2019 (Pelto et al. 2019) comparing glaciological (field) and geodetic (LiDAR) mass balance estimates and found them to be similar — if some factors like snow and firn density were carefully considered. The small difference between estimates is likely due to timing (the LiDAR mass balance is from 8/26/2020 to 9/3/2021, while the field mass balance is 9/12/2020 to 9/13/2021), and that there was a skiff of fresh snow (likely 5-10 cms) on the glacier during the 2020 LiDAR survey.
Kokanee 2021 glacier mass balance. Blue dots are observations. The boxplots show the 100 m bins used to estimate glacier-wide mass balance (median line in black, mean dashed grey line). The grey bars depict the area of the glacier for each 100 m elevation-band
In 2017, I visited the Kokanee Glacier to measure it’s ice thickness using ice-penetrating radar. I found that the glacier on average was 43 m thick using my measurements to tune a glacier model. I published these results in the Journal of Glaciology (Pelto et al. 2020). In the five years since that work, the glacier has lost over 4.8 m of total thickness. That equates to a loss of over 11% of its total volume. 2021 alone wasted away 6% of the glacier’s total volume — an eye-watering number for a single year.
Cumulative mass balance for Kokanee Glacier 2013-2021 from both field and LiDAR measurments. LiDAR-derived mass balance began in 2016.
The heat of 2021 was an outlier, but years like 2021 and 2015 take a toll on the glaciers. Currently, glaciers in western North America are losing around 0.75 m of thickness per year (according to my work in the Columbia Basin (Pelto et al. 2019) and work by Brian Menounos for all of western North America (Menounos et al. 2018)). The better years for Kokanee Glacier (2016 mass balance: +0.12 m w.e.) pale in comparison. That meager surplus was lost the very next year (2017).
Herein lies the issue, positive mass balance years in recent decades are not large enough to offset even average years; hot dry summers take years off the lifespan of glaciers across western North America.
Losing 6% of it’s total volume in 2021, the best we can hope for Kokanee Glacier is a few near-neutral or positive mass balance years to cover back up the exposed firn, to keep the glacier albedo from becoming too dark and increasing the rate at which ice can melt.
Bonnet Glacier in Sentinel 2 images indicating the emergence of bedrock due to thinning in the former accumulation zone, Point A. Note the lack of retained snowcover in both years with at least a month left in the melt season.
Bonnet Glacier, Alberta drains north from Bonnet Peak in the Sawback Range 30 km east of the Rocky Mountain Crest. It is at the headwaters of Douglas Creek that feeds into the Red Deer River. In 2017 we reported on the formation of new alpine lakes and the 900 m retreat of the glacier, 20% of its length, from 1987-2016 (Pelto, 2017). Here we examine changes from 1987-2021, including developments in the accumulation zone that provide a future forecast. An inventory 0f glaciers in the Canadian Rockies indicated area loss of 15% from 1985 to 2005 (Bolch et al, 2010), with Alberta glaciers losing area at a higher rate. 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. Columbia Icefield, 125km northwest, lost 23 % of its area from 1919-2009 (Tennant and Menounos, 2013).
In 1987 and 1990 the accumulation zone is limited to upper periphery of Bonnet Glacier. In 2015 and 2016 the accumulation zone is restricted to the northeastern periphery. This is indicative of a glacier without a significant persistent accumulation zone. The consistent mass loss is driving the retreat and glacier thinning. In 2018 in the midst of what had been the accumulation zone a small area of bedrock has emerged at Point A. By 2021 this area has expanded substantially with the two bedrock areas poised to merge soon. This thinning in the midst of the former accumulation zone is indicative of a glacier that cannot survive (Pelto, 2010). In 2015, 2018 and 2021 the accumulation area ratio was between 10-15%, a value that typically results in glacier annual mass balance of more than -2 m. The area of main proglacial expanded 50% from 2016 to 2021 to 0.33 square kilometers.
Bonnet Glacier in Landsat images from 1987, 2016 and 2021 indicating retreat. Red arrows indicate 1987 margin, yellow arrows 2016 and the green arrow 2021. Point A indicates the emerging bedrock.
Bonnet Glacier in Landsat images from 1990, 2015 and 2021 indicating retreat. Purple arrows indicate lakes that have formed due to retreat. Point A indicates the emerging bedrock.
Southeast #3 Glacier, Devon Ice Cap in July 9, 2016 and August 29, 2021 Sentinel 2 images of the lower 10 km showing three supraglacial streams S1, S2 and S3 and the outlet plumes of each stream at Point 1-3. The yellow line is the 2016 margin.
The southeast sector of the Devon Ice Cap, Devon Island, Nunavut has three tidewater outlet glaciers Southeast Glacier #1, #2 and #3. Van Wychen et al (2017) indicate the dynamic discharge of the three at .06-.07 Gt per year, all three glaciers have been retreating during this period. Southeast #3 is between 0.01 and 0.02 Gt per year. Sharp et al (2011) note that increasing summer temperatures has led to increased mass loss on Devon Ice Cap. Here we examine retreat and the supraglacial stream networks using Landsat and Sentinel 2 imagery.
In 2002 the calving front of Southeast #3 Glacier extended north from with five distinct peninsulas of ice. The retreat by 2016 was more pronounced on the north south oriented southern portion of the front than the northwestern part. From 2016 to 2021 it is evident that the glacier front has receded, particularly at the prominent ice peninsulas evident in 2016. The retreat averages 600 m across the 5 km wide tidewater front seen above from 2016-2021. This is an addition to the 1200 m retreat from 2002-2016, while the northwestern section retreated ~500 m during the 2002-2021 period. S1, S2 and S3 indicates supraglacial stream drainages that exit the glaciers at Point 1-3 respectively. The plumes of sediment from these streams is evident in the July 24, 2020 image below from each of these surface outlet streams. The plumes are evident in the July 2016 image, but no the late August image of 2021. The lack of plumes on 8-29-2021 indicate the lower melt rates that are typical of late August. The stream network has become more prominent as melt rates have led to greater flow and more incising into the ice.
This retreat has occurred during the same period that was noted as generating three new islands in 2018 on the northeast margin of the Devon Ice Cap. Noel et al (2018) observe that this is part of a trend seen across Canadian Arctic ice caps have been losing mass for decades and that mass loss accelerated in 1996.
July 24, 2020 Sentinel 2 image of the lower 10 km of Southeast #3 Glacier showing three supraglacial streams S1,S2 and S3 and the outlet plumes of each at Point 1-3.
Southeast #3 Glacier in 2002 and 2021 Landsat images. Yellow dots indicate the 2002 margin of the glacier.
Adams Glacier in Sentinel 2 False Color image from 8-30-2021. Green dots indicate margin of the Adams Glacier and the now separated Adams Outlier section. The pink arrows indicate the top and bottom of the icefall. F=regions of exposed firn, A=areas of perennial retained accumulation.
Adams Glacier descends the north side of Mount Adams a 3743 m stratovolcano in the Cascade Range of Washington. The glacier begins from the summit plateau between 3600 m and 3700 m, before descending a steep icefall down to 2750 m and then diverging on lower slopes terminating at 2225 m. Sittts et al (2010) mapped the area change of Mount Adams glaciers from 1904 to 2006. The area was 6.93 km2 in 1904 declining to 5.16 km2 by 1969, 4.62 km2 by 1998, and 3.68 km2 in 2006. This decline since 1969 has been due largely to increased summer temperatures (Sittts et al 2010) . Here we examine the impact of the particularly warm summer of 2021 on snowpack, glacier volume and reassess the area of the glacier. The winter of 2021 had above average snowfall with 157% of the mean peak winter snowpack in April at the nearest Snotel site at Potato Hill ( 1375 m), the snowpack loss date after a dry May was the same as usual, see figure below. The mean June-August temperature at the Mount Adams Ranger Station (600 m) was the second warmest for the 1984-2021 period to 2015.
Snowpack loss from June 21 to August 25 in Sentinel images. AO=Adams Outlier, T=Terminsu Zone, I=Icefall, S= bergshrunds on upper glacier.
On June 21, 2021 nearly the entire glacier is snowcovered, which is typical. By July 1, 2021 areas of the glacier below the icefall are rapidly losing snowcover. By August 15, 50% of the glacier has retained 2021 snowcover. This rapidly diminishes to ~10% by Aug. 25, 2021. On Aug. 30, 2021 there are large areas above 10000 feet that typically retain snowcover to the end of the summer that have lost all snowcover and are particularly dirty firn, snow that fell in recent years but has not been converted to glacier ice. The retained snowcover is in five patches, the lower three are all avalanche runout zones and the upper two regions, above the icefall, of wind drift redeposition.
Adams Glacier in Sentinel 2 True Color image from 8-30-2021. Pink arrows indicate icefall top and bottom. S=summit area, A=Areas where limited pockets of 2021 snowpack has been retained through August.
Similar to Whitney Glacier on Mount Shasta , Adams Glacier will not retain snowcover in 2021. The early exposure of bare firn and ice, which melt at a faster rate than snow is causing rapid mass losses on the upper glacier this summer, as we have reported from Easton Glacier on Mount Baker. The current area of the main glacier is 1.9 km2, with the outlier have an area of 0.3 km2. The combined area of 2.2 km2 is less than 50% of the 1998 total. The loss of snowpack from the Adams Glacier is greater than in any year since 1984, exceeding 2015. The winter of 2015 had less snowfall and the mean summer temperature was warmer. The key difference is likely the excessive melt of the late June 2021 heat wave that is particularly impactful early in summer. Finn et al (2017) noted that the upper reaches of Adams Glacier ranged from ~25 to 60 m thick, while lower down on the volcano are the glacier is less than<~30m thick. This summer mass losses will be in the 2-3 m range on Adams Glacier, based on the duration of exposed ice and percentage of the glacier in the accumulation zone. This will represent a 5-10% volume loss for this glacier in 2021.
Snowpack at Potato Hill (1375 m) a Snotel site. The 2021 winter had above average peak snowpack (black line), but typical melt out date.
Sentinel 2 False and True Color images from 8-25-2021. Yellow arrows indicate where glacier is separating and purple arrows the small remanent of 2021 snowpack remaining. This remanent will not last to the end of the melt season.
The summer of 2021 is proving to be catastrophic for Whitney Glacier on Mount Shasta, California in terms of volume loss, ~15-20% this year leading to long term impacts, adding to the 50% area reduction and 1000 m retreat since 2005. The glacier will lose 100% of its 2021 snowpack and is in the process of separating into two glaciers. Here we review the glaciers behavior in recent decades and examine using Sentinel Imagery the impacts in summer of 2021.Mount Shasta is a stratovolcano home to the largest glaciers in California, Whitney Glacier on the north side is the longest. In 1981 USGS (Driedger and Kennard, 1986) mapped the area and volume of several of the glaciers, in a landmark study of glacier volume on Cascade volcanoes. Whitney Glacier had an area of 1.3 km2, a maximum depth of 38 m, and a volume of 25 million m 3. The majority of the glacier was in the 20-35 m thick range. The glacier was noted as having a length of 3.0 km ending on the USGS map at 9900 feet.
Digital Globe image indicating a area of retreat from 2005-2012 and the limited crevassing near 2012 terminus.
Tulaczyk and Howat (2008) noted that Whitney Glacier did advance during the 2000-2005 period, following a retreat in the 1980’s and 1990’s. The most recent advance was limited to the 1999-2005 period due to heavy snowfall from 1998-2002, ended with the glacier 850 m in advance of its 1951 position. There was a period of advance for many Cascade volcanoes glaciers between 1950 and 1980, followed by retreat after. On Mount Baker, Washington all of the glaciers advanced during the 1944-1979 period by an average of 480 m (Pelto and Hedlund, 2001). By 2010 Pelto and Brown (2012) observed all were retreating with an average retreat of 370 m. In 2012 the glacier is thin in its lower reaches with no crevassing. By 2014 the terminus of the glacier had retreated 700 m from 2005 and was 2.6 km in length and terminated at 10200 feet, 300 feet higher than a decade before or in the 1981 map.
Sentinel 2 True Color images from 6-16-2021, 6-28-2021 and 7-18-2021 illustrating the progressive snowcover loss on the glacier. Point A and D are on the upper Glacier, Point B is where the upper and lower glacier have joined and Point C is near the top of the lower glacier.
The summer of 2021 followed a 15 year period of overall significant mass loss and retreat on Whitney Glacier that led to a thinner glacier with a reduced velocity and consequently fewer crevasses. The stage was set with 60-75% of normal snowpack in early April 2021 at the stations in the region in the 6000-7600′ range, dropping to 20-25% of normal by early May (CDEC, 2021). This was followed by an exceptionally warm early summer, that helped strip the snowpack away early. By June 16, the snowline on Whitney Glacier had risen to 10,800 feet, near Point C, while the upper glacier extending from Point A and D to Point C was nearly all snowcovered. By June 28 the snowline had risen to 11,200 feet on the lower glacier and the upper glacier snowline was near 12,500 feet, with the west facing upper section (Point A) above 13000 feet nearly all bare. By July 18 there is a small area of snowcover near Point C on the lower glacier and Point D on the upper glacier. Most of the glacier is bare of snowcover. This underscores the particularly detrimental impact of early season heat waves that strip away winter snowpack and exposes the dirtier glacier ice and firn. The ice and firn melt ~30% faster than the snowcover for the same weather conditions. Our measurements on Mount Baker during heat waves over the last three decades indicate typical ice melt of 7-9 cm of melt per day. The average temperature over the last 70 days since much of the glacier was bare ice has been 16.8 C at Snow Bowl station at 7617 feet. Given area summer lapse rates this equates to a temperatures of ~12-13 C at the mean glacier elevation. The temperature at this station reached 29 C on June 27, 28 C on June 28 and exceeded 25 C from June 25-June 30. The rapid melt rate led to a number of areas of slushy, swampy glacier surface conditions even high on the glacier (Mount Shasta Avalanche Center ). Using the degree day formula for melt derive on Mount Baker during warm summer conditions (Pelto, 2015 and 2018) of .0053m w.e.C-1D-1, yields a cumulative melt of 4.8 m w.e., equivalent to over 5 m of ice thickness.
This given mean ice thickness in the 25-30 m range indicates that this summer ~15-20% of the glacier ice volume will be lost on Whitney Glacier. The glacier is now 2300 m long and has an area of 0.6 km 2, which is less than 50% of its area just 16 years ago. This is leading to separation of the lower and upper glacier at the yellow arrows. There is certainly still stagnant ice in this zone, but there is no longer a dynamic connection between the upper and lower Whitney Glacier.
Topographic map of Mt. Shasta.indicating the top of Whitney Glacier near the summit of Shasta and the ~1981 and 2005 terminus position.
Terminus of Columbia Glacier on left with 1984 terminus location noted. Observe the avalanche fans (A) and the relatively high snowcover on 8-2-2021. At right is Easton Glacier on 8-11-2021 with the location of the 1990 terminus indicated, 440 m of retreat to the 2021 terminus position. The glacier has only 38% snowcover at this time, which is better illustrated below.
Columbia and Easton Glacier in the North Cascade Range of Washington are two of the reference glaciers for the World Glacier Monitoring Service. We have monitored their mass balance in the field for 38 and 32 years consecutively. This year Ashley Parks, Sally Vaux, Jill Pelto and I worked on all of the glaciers with Abby Hudak, Rose McAdoo and Ben Pelto joining us for either Easton or Columbia Glacier. In 2021 a combination of an above average winter snowfall and a record summer melt has led to a different story of mass balance for the two glaciers. At Mount Baker and Stevens Pass winter snowpack on May 1 was 116% and 115% of normal (NWAC, 2021). From June 1-Aug. 17 the mean average temperature is similar to 1958 and 2015, and well above every other year. With the maximum temperature exceeding 80 F on 17 days during this period at Stevens Pass ( 3950 ft, 1200 m), each of those days represents exceptional melt conditions. Our observations indicate 11-14 cm of snowpack melt on glacier during exceptionally warm days like this. Just the melt from these 17 days would equate to half of the average summer melt for a North Cascade glacier (Pelto, 2018). The earlier summer heat wave has led to exposure of greater higher albedo and faster melting glacier ice, which is why such a heat wave is more impactful than in late summer.
Columbia Glacier occupies a deep cirque above Blanca Lake ranging in altitude from 1400 meters to 1700 meters. Kyes, Monte Cristo and Columbia Peak surround the glacier with summits 700 meters above the glacier. The glacier is the beneficiary of heavy orographic lifting over the surrounding peaks, and heavy avalanching off the same peaks. Standing on the glacier is a bit like being in the bottom of a bath tub, with avalanche slopes extending up both sides, predominantly on the west side. The last half of January 2021 was a dry period in the region, with an extensive crust forming on the snowpack. This was followed by 106 inches of dry snowfall from Feb. 4 to Feb. 20,and then 34 inches of wet snowfall and even rain through Feb. 24 This generated extreme avalanche danger and numerous climax avalanches in the Stevens Pass region.
NWAC’s avalanche forecast on 2/20 for Stevens Pass indicated that, “We haven’t seen rain above 3,500ft or so since mid-January, so one of the main concerns is that slabs 5-10′ feet thick may begin to come crashing down. The avalanche cycle(s) may last through the day Monday. In any case, very large storm slabs and wet loose avalanches are expected to continue to run from steep slopes through Monday as our once beautiful cold, dry snow becomes overloaded by wet, heavy rain and snow.”
The avalanche slopes with many pockets above Columbia Glacier in Aug. 2020, one fan can be seen bottom center. These have to filled each winter season before slides occur, in 2020 avalanching was limited.
As we headed up onto Columbia Glacier on Aug. 1, 2021 we noted a significant number of large avalanches had descended near and onto the glacier. The glacier was 87% snowcovered, including the terminus area. This is well above the recent early August average. As is the case every year we measure snow pack depth in a grid across the entire glacier. Snow depth in the three biggest west side avalanche fans averaged 4.9 m, 25% above normal. The three largest fans comprise an area of 0.14 km2, yielding a volume of 686, 000 m3 swe. The melt season ends in another month, however, due to this substantial avalanching that will keep this section of the glacier covered in snow, Columbia Glacier will have a small-moderate negative mass balance.
Ashley Parks, Jill Pelto and Sally Vaux measuring snow depth in the Columbia Glacier avalanche fans.
The three primary avalanche fans each had a slope of 23 degrees. Here we are spaced out at 50 m intervals mapping the size of the fan.
Easton Glacier on the south flank of Mount Baker does not recieve avalanche accumulation, and the regions above 2500 m, typically have significant wind scouring, that leads to little increase in mass balance with elevation above this elevation on the upper glacier. There are both basins where snow is preferetially deposited by wind and convex regions where snowpack is scoured. In 2021 enroute to the glacier terminus we observed considerable stunted alpine vegetation, that emerged and then did not grow. This was prevalent on rocky slopes that were exposed during the heat wave. The example below is of Lupine with the growth from last year now brown and flat indicating the stunted size this year.
Stunted Lupine, each patch is typically 20-30 cm high and equally broad. Here the plants are 3-5 cm high.
On Aug. 11, 2021, the glacier had only 38% snowcover, with more than 50% of the area above 2500 m having lost all winter 2021 snowcover. By summer’s end the glacier will certainly have the lowest percentage of snowcover of any year since we began monitoring in 1990. The bench at 2000 m typically has 2.75 m of snowpack on Aug. 10, and this year was 50% bare, with an average depth of 0.25 m. The icefall above also lacked snowcover as well. There are a number of pockets/basins, where wind deposition increased snow depth and this snowpack will be retained.
The observations across the range illustrated that glaciers or areas of glaciers that do not have enhanced deposition from wind drifting or avalanching are either bare already or will be by the end of August. The full extent of the loss on Columbia and Easton Glacier from this summer will be evident in a month. What is apparent is that the losses from Easton Glacier will be extraordinary. More frequent heat waves continue to plague alpine glaciers, these can even occur in winter such as on Mount Everest in January 2021 (Pelto et al. 2021)
View of the lack of snowcover in the icefall at 2000-2300 m on Easton Glacier. The lack of snowcover above this point is also evident in the upper image.
Rose McAdoo and Jill Pelto measuring the 2021 snowpack at 2350 m is alareay thinner than the 2020 or 2019 retained snowpack and will be gone by the end of the month.
In 2021, I am in front of the same serac as in 2020, down slope. The average retained accumulation at this 2600 m location in the laterally extensive layers is 2-2.2 m. This year there will no retained accumulation.
Ben and Jill Pelto amongst the seracs where snowpack should be extensive, but in 2021 they are standing on 2020 firn.
Topographic map of Mt. Shasta.indicating the top of Whitney Glacier near the summit of Shasta and the ~1981 and 2005 terminus position.
From a Glaciers Perspective 