Steffen Glacier in 2024 False Color Sentinel images illustrating calving events yielding bergs A,B,X and Y that have a combined area of 1.5 km2.Green arrow is Dec. 2023 terminus and yellow arrow April 2024 terminus. Each berg has consistent notation.
Steffen Glacier is the largest south flowing outlet of the 4000 km2 Northern Patagonia Icefield (NPI). Several key research papers have reported on the spectacular retreat of this glacier in recent years. Glasser et al (2016) reported that Steffen Glacier proglacial lake area expanded from 12.1 km2 to 20.6 km2 from 1987 to 2015, due in part to a 100 m snowline rise. Dussaillant et al (2018) determined annual mass loss of NPI at ~-1 m/year for the 2000-2012 period, with Steffen Glacier at -1.2-1.6 m/year. The result Steffen Glacier retreat from 1987-2019 was 4.4 km, ~137 m/year (Pelto, 2019).
On December Dec. 6, 2023 the terminus tongue has a narrow unsupported section that appears poised to calve (C). By Dec. 26, 2023 the glacier has calved berg C (0.4km2 ), joining other large bergs remaining from previous years D, E and F. Two more pieces A and B appear poised to calve. By Feb. 9 2024 berg B has calved, and by Feb. 24 berg A has calved, together they are 0.3 km2.
On April 14 two more large bergs X and Y have calved from the terminus. Berg X is the largest of the year at 0.6 km2, berg Y is 0.2 km2 . Terminus retreat from Dec. 2023-April 2024 is 1.5 km. The terminus tongue is again narrow and unsupported as the winter season begins, indicating that more large icebergs should be expected in the 2025 summer season. Millan et al (2019) indicate the area of tributary glacier convergence near the northwest terminus and above the glacier is 700 m thick, and that the glacier has been retreating along an area where the glacier bed is below sea level, though the terminus now is close to sea level.
Steffen Glacier in Dec. 2023 False Color Sentinel images illustrating calving event yielding berg C.Green arrow is Dec. 2023 terminus and yellow arrow April 2024 terminus.
Grace (G), Lucas (L) and Price (P) Glacier’s in 4-6-2024 Sentinel image top, yellow dots mark the 1987 terminus position when all reached tidewater, blue dots indicate 2024 terminus. Below is the South Georgia GIS with terminus observations from the BAS shown.
In 1987 Grace, Lucas and Price Glacier on the northern end of South Georgia Island each reached tidewater. Each had retreated less than 100 m since 1976. This is a very cloudy region and clear satellite image views limited. Here we examine Landsat images from 2000 and 2016, and a Sentinel image from 2024 to identify changes. Gordon et al., (2008) observed that larger tidewater and sea-calving valley and outlet glaciers generally remained in relatively advanced positions until the 1980’s. After 1980 most glaciers receded; many of these retreats have been dramatic including Twitcher, Herz, Ross, Hindle, Konig and Neumayer Glacier (Pelto, 2017).
By 2002 a Landsat image reveals that Grace and Lucas Glacier have retreated from the coast with new proglacial lakes forming between the terminus and the coast. Price Glacier main terminus is still filling most of a narrow bay, and the east side of the terminus is still reachig the coast. By 2016 Grace Glacier retreat has led to the formation of several small proglacial alkes, while Lucas Glacier retreat has generated one larger proglacial lake. Price Glacier has begun to retreat up a narrow embayment and the east side has almost lost connection with tidewater.
In 2024 Grace Glacier has retreated 1200 m, ~20% of its length in 1987. Lucas Glacier has retreated 1400 m, ~20% of its length. Price Glacier now only terminates in a narrow embayment ,has retreated 1700 m, ~23% of its length. Each glacier has limited area above 500 m, indicating that below this elevation glacier mass balance has been significantly negative over the last 35 years. The retreat here is similar to that of Konig and Turnback that have retreated from tidewater exposing new coastal regions that are being occupied by flora and fauna.
Grace (G), Lucas (L) and Price (P) Glaciers in 2002 and 2016 Landsat images as they retreat from tidewater.
Volcan Overo Glaciers at the end of the 2024 melt season in a false color Sentinel image from 3-30-2024. There is no sigificant area of snowcover remaining for the 3rd consecutive summer. The lake that had formed at Point A since 2018 has now drained. Fragmentation at point B, C, and D continue, while thinning at top of glacier is apparent with expanding bedrock knob at Point E.
Volcan Overo is a 4619 m high Andean mountain in Argentina with a relatively low sloped broad volcanic summit region above 4000 m that hosts a glacier complex that is shrinking and fragmenting. La Quesne et al (2009) observed significant annual thinning in the latter half of the 20th century on nearby glaciers in Argentina and Chile. A sharp increase in mass loss on Central Andean glaciers after 2009, including the Volcan Overo region, was reported by Ferri et al (2020). Here we examine Landsat images from 1986-2022 to identify longer term changes of the glacier and Sentinel images from 2018-2024 illustrating the persistent lack of an accumulation zone leading to recent changes, including the impact of the January 2023 heat wave (Washington Post, 2022). The persistent lack of an accumulation zone during the 2018-2024 period, highlighted in images below, in which no snow was retained as firn, indicates the glacier cannot survive (Pelto, 2010).
Volcan Overo in Landsat images from 1986-2022 illustrating area loss and fragmentation.
In 1986 there are four discrete glaciers around the caldera, covering ~12 km2 the largest E around the summit ranges in elevation from 4200-4500 m. D is an isolated area at 4000-4100 m. A,B and C is a single glacier extending from 3900-4300 m. F is an area of rapidly diminishing glacier ice.
In the early February image snowcover is good across all ice areas except F. In 2003 there is limited evident change with good snowcover across all except D. By 2013 A, B and C have fragmented into three separate glaciers and F is nearly gone. Only E has significant snowcover.
In 2022 C and D in the Landsat images have declined to less than 50% of their 1986 area, the overall Volcan Overo glaciated area has declined to ~8.1 km2. It is not quite mid-summer on January 8, 2022 yet all snowcover has been lost from the glaciers of Volcan Overo. The glacier remnants at F are now gone.
Volcan Overo Glaciers at the end of the 2018 melt season in a false color Sentinel image from 3-17-2018. There is no sigificant area of snowcover remaining. A lake is forming at Point A . At Point B this is a single glacier. At Point C an expanding ridge is still narrow and segmented. At Point D three glaciers areas are just losing contact and at Point E a small knob has emerged from ice cap.Volcan Overo Glaciers at the end of the 2020melt season in a false color Sentinel image from 3-11-2020. There is no sigificant area of snowcover remaining. A lake has formed at Point A . At Point D three glaciers areas are clearly separated.Volcan Overo Glaciers at the end of the 2022 melt season in a false color Sentinel image from 3-09-2022. There is no sigificant area of snowcover remaining. The lake at Point A is expanding . At Point B the glacier is separating into two parts.. At Point C an expanding ridge is now continuous segmented. Volcan Overo Glaciers at the end of the 2023 melt season in a false color Sentinel image from 3-09-2023. There is no sigificant area of snowcover remaining for the 2nd consecutive summer. The lake that had formed at Point A has expanded further. Fragmentation at point B, C, and D continue.
The impact of heat waves in 2022 and 2023 has taken its toll on the glacier.
Great Glacier terminus change from 1986-2022 illustrating lake expansion. Red arrow=1986 terminus location, Yellow arrow=2022 terminus location.Terminus has retreated 2.1 km during this time with the lake growing 15 km2.
Great Glacier is the largest outlet glacier of the Stikine Icefield feeding the Stikine River. The name came from the large expanse of the glacier in the lowlands of the Stikine River during the late 19th and early 20th century, that has now become a large lake. In 2023 I worked on a signage project for the Great Glacier Provincial Park with Hailey Smith, BC Park Ranger, documenting the changes in this glacier particularly since 1914.
The glacier filled what is now a large lake at the terminus of the glacier pushing the Stikine River to the east side of the valley. The Tahltan nation oral history relates when the glacier bridged the Stikine River and meet Choquette Glacier. In 1914 the glacier was easy to ascend from the banks of the Stikine River, the picture above is from the National Railroad Archive. By 1965 the new lake had formed, but the glacier still reached the far side of the lake in several places as indicated by the 1965 Canadian Topographic Map below. R. Patterson (Writer and Canadian Explorer 1898-1984) noted that Great Glacier came down onto the river flats, and displayed a 7 km front visible from the Stikine River.
Map of Great Glacier in 1965 illustrating the fringing lake.
Landsat images from 1990 and 2022, illustrating changes in the glacier and lake. The transient snowline is at ~900 m in both images.
A comparison of 1986, 1990, 2011 and 2022 illustrates the retreat. By 1986 the new lake had largely developed, and the glacier was beginning to retreat into the mountain valley above the lake. Retreat from the moraines of the late 19th century was 3200 m. By 2011 the glacier had retreated further into valley, 900 m retreat from 1986-2011. From 2011 to 2022 the glacier retreated another 1200 m. The lake has expanded to an area of 15 km2
A view of the glacier from across the lake today indicates the distance to the now valley confined glacier, and the trimlines of the former ice surface, yellow arrows in middle image The Great Glacier has one major tributary on the northeast tributary that is very low in elevation with a top elevation of 800 m. Given the regional snowline of 1100-1200 meters in the 1980s (Pelto, 1987) this is too low to retain snowcover through the summer and will lead to rapid progressive thinning. In 2018 and 2019 the highest observed snowlines in the region occurred, the snowline averaged 1500 m, leaving just 10% of the Great Glacier snowcovered. This is instead of the 60% needed to maintain equilibrium. Stikine Icefield outlet glaciers are all undergoing substantial retreats including Sawyer Glacier,Baird Glacier and Dawes Glacier.
Great Glacier snowline end of summer in 2018 and 2019 reached the highest levels observed at 1500-1600 m.
Eagle Island Ice Cap has 65% snowcover on Feb. 27, 2024 in Sentinel images. After 5 of the next 10 days reached at least 9 C at Esperanza Base the snowcover is just 8% on March 8, 2024.
On February 27, 2024 Eagle Island had ~65% snowcover, by March 8, 2024 this had diminished to just 8% snowcover. This matches last year for the lowest observed snowcover of this ice cap. On February 19, 2023 Eagle Island Ice Cap, Antarctica has less than 10% snowcover. This is less snowcover than observed even after the period of record warm weather over the Antarctic Peninsula in February 2020. The repeat loss of snowcover has stripped the ice cap of firn exposing bare glacier ice that is darker and melt faster, enhancing melt losses. Temperature when the all time Antartica temperature record was set at Esperenza Base. Eagle Island Ice Cap (63.65 S 55.50W) is 40 km from Esperanza, with the summit of the ice cap is at 250-300 m and it has an area of 21 km².
In March the temperature reached 9 C on March 4, 6, 7 and 8.
In 2020 we observed blue ice areas (BI) and saturated snow areas (SS) rapidly developed from a snow covered ice cap during the heat wave (NASA EO, 2020). The impact of short term melt events like this on an ice cap like this, is visible and significant for annual mass balance, but not large in terms of long term glacier mass balance (volume change) and area. That year also led to record melt and ponding on the George VI Ice Shelf (Banwell et al, 2021). In 2022 a similar patter of blue ice developed, but no saturated snow. In 2023 the loss of snowcover was nearly complete exposing a more extensive bare ice and firn surface area that melts more rapidly. This was the result not of a heat wave but of a consistenly warm summer.
Eagle Island Ice Cap rapid snow melt and resultant melt ponds during record warmth in Feb. 2020seen in Landsat images.Eagle Island Ice Cap in Sentinel image illustrating 8-10% snowcover on 2-19-2023.
Bernardo Glacier in Sentinel images from Dec. 26, 2023 and Feb. 9, 2024 illustrating the drainage of the southern end of the proglacial lake by the northern terminus. The lake was full in 2021, partially drained by Oct. 2022, further drained by March 2023 and did not refill through Sept. 2023. The lake refilled between September and December 2023 . And drained again by Feb. 9,2024. Channel location appears to be at Point C. There is 9 km2 of exposed lake bed.
Bernardo Glacier in Sentinel images from Oct. 16, 2022 and Sept. 17, 2023 illustrating the drainage of the southern end of the proglacial lake by the northern terminus (N). The lake was full in 2021, partially drained by Oct. 2022, further drained by March 2023 and has not significantly refilled by Sept. 2023, still 8 km² of exposed lake bed.
Bernardo Glacier in Landsat images from 1986 and 2021 illustrating retreat at the southern (S), middle (M) and northern (N) terminus respectively. Red arrows are 1986 terminus locations, yellow arrows are 2021 terminus locations. Separation from Tempano (T) occurs at southern terminus, while lake expansion occurs at M and N.
Retreat of Bernardo Glacier in Landsat images from 2003 and 2015.
In 1986 Bernardo the southern terminus of the glacier was in tenuous contact with Tempano Glacier. The middle terminus primarily ended on an outwash plain with a fringing proglacial lake developing. The northern terminus had retreated a short distance south from a peninsula that had acted as a pinning point. A small lake developed completely separating Bernardo Glacier and Tempano Glacier. By 1998 the northern terminus had retreated into the wider, deeper portion of the lake basin that was now filled with icebergs. In 2015 the northern terminus had retreated 3.5 km since 1986. By 2021 the northern terminus had retreated 4.1 km. This led to a 7.8 km² lake expansion at the northern terminus, with a total lake area of 17.5 km².
On October 2, 2022 the water level had dropped some, with lake area falling slightly. The lake continued to fall through the summer season of 2023. The lake did not refill through the winter and into the spring, September 2023, with the lake having an area of 9.5 km², and 8 km² of lake bed still exposed. The lake did refill by December 2023, and then drained to an even greater extent then in 2023 as of Feb. 2024. Continue glacier thinning and retreat will reduce the ability of the glacier to continue to dam this lake. Gourlet et al (2016) identify Bernardo Glacier as having thinner ice than other large outlet glaciers such Jorge Montt or O’Higgins, which helps lead to rapid terminus change.
Southern Andean huemel an endemic deer on the foreland beyond Bernardo Glacier (Photograph from Eñaut Izagirre
The snow line on Mount Everest Region glaciers on Feb. 11, 2024 indicated by yellow dots on the Landsat image. Note that Nangpa La and Nup La-two high passes (5800-5900 m) are both snow free. The average snow line is 6000 m.
The snow line on Mount Everest Region glaciers on Oct. 30, 2023 indicated by yellow dots on the Landsat image. Note that Nangpa La and Nup La-two high passes are both snow covered. The average snow line is 5700 m.The snow line on Mount Everest Region glaciers on Nov. 15, 2023 indicated by yellow dots on the Landsat image. Note that Nangpa La and Nup La-two high passes are both snow covered. The average snow line is 5800 m.The snow line on Mount Everest Region glaciers on Jan. 10, 2024 indicated by yellow dots on the Landsat image. Note that Nangpa La and Nup La-two high passes are both snow free. The average snow line is 5950 m.Cumulative precipitation through the year at Everest Base Camp. The typical dry period begins in October and extends into Februrary, but this year is the lowest since the National Geographic Rolex Perpetual Planet weather station was installed.
In several recent years including Winter 2017/18, 2020/21 and 2023/24 the snow line has risen substantially on Mount Everest glaciers from October into the mid-winter period (Pelto et al 2022).. This indicates not just dry conditions, but conditions that allow significant ablation at the snow line, which has risen 150-300 m during each of these periods on the glaciers. The ablation can be from melting or as the case this winter sublimation, which can lead to losses up to 2.5mm/day (Tenzing Chogyal Sherpa et al 2023). When will snow finely cover the glaciers in the Everest region?
The snow line (yellow dots) on Mount Everest region glaciers on Feb. 11, 2024 in this Landsat image average 6040 m. This is a 200 m rise from October 22, 2023 and a 20 m rise since Jan. 10, 2024. The passes at Nangpa La and Nup La are both snow free.
The snow line (yellow dots) on Mount Everest region glaciers on Jan. 10, 2024 in this Landsat image average 6020 m. This is a 200 m rise from October 22, 2023. The passes at Nangpa La and Nup La are both snow free. The rise has occurred during a prolonged dry period, temperatures have been cold as is typical.
Mount Everest glaciers are summer accumulation-type glaciers with ~75% of annual precipitation occurring during the summer monsoon (JJAS). The summer monsoon period also has the highest melt rates at lower elevations on the glaciers. October has been considered the end of the melt season in the region, with limited precipitation in the post-monsoon and early winter season (October–December). Winters (DJF) are cold and dry, though they do have the most variable precipitation.
A rising snow line elevation on glaciers in the region from October to February indicates significant ablation occurring during the first half of the winter season on glaciers in the Mount Everest region. The series of weather stations on Mount Everest installed by the National Geographic Expedition-Perpetual Planet in 2019 and with repeated updates and maintenance since provides the ability to put the snow line change in context of the local conditions for the first time. higher snow line at the end of summer monsoon season in 2020 and 2023, combined with warmer post-monsoon, and dry winter conditions, can drive a snow line to rise from October into the winter on Himalayan glaciers, thus extending the melt season (Pelto et al 2022). An examination of winter weather conditions from stations on Mount Everest documented that substantial sublimation rates with losses up to 2.5mm/day occur (Tenzing Chogyal Sherpa et al 2023).
The snow line (yellow dots) on Mount Everest region glaciers on Jan. 17, 2021 in this Landsat image average 6150 m. This was a 250 m rise from Oct. 13, 2020. The passes at Nangpa La and Nup La are both snow free. The rise has occurred largely during a period of record winter warmth extending from Dec. to Jan.
On Oct. 22, 2023 a Landsat image allowed identification of the snow line on Everest region glaciers, which averaged 5800 m. From Nov. 1-2023 to Jan 20, 2024 there has been less than 25 mm of precipitation at Everest Base Camp (5315 m), this persistent dry period had one period of warm weather from Dec 14-Dec. 22, with six days exceeding 0 °C. From Dec 23-Jan 20 winter, temperatures have remained below 0 °C. Daily images from. The EBC weather station have yielded a nearly continuous series of clear sky days. The result has been sustained sublimation that is important for snow loss, despite the low temperatures solar radiation does generate ablation even when temperatures do not exceed 0 °C for ice, and snow in regions with significant debris material (Matthews et al 2020). The result the average glacier snow line has risen above 6000 m by January 10, 2024 and has remained above this level into Februrary 2024.
During the 2020/2021 winter the snow line rose an average of over 200 m from 13 October 2020 to 17 January 2021, with freezing levels indicating ablation to ~6000 m (Pelto et al 2022). This snow line rise was driven by a combination of dryness and warm temperatures, with ERA5 reanalysis temperature reconstructions for Everest Base Camp (5315 m) for the 1950–February 2021 period indicating that six days in the January 10–15 period in 2021 fell in the top 1% of all winter days since 1950, with January 13, January 14, and January 12, being the first, second, and third warmest winter days. Note in the graph below that temperatures rose above 0 °C on 11 consecutive days. The temperature also exceeded 0 °C on seven days in December.
In 2020/21 the conditions remained warm and dry into mid-January (Pelto et al 2022), while in 2023/24 the conditions have been cooler and dry. In both cases the rising snowline is the result of sublimation. Relative humidity measured at the has averaged less than 20% at the EBC in January 2024 (National Geographic-Perpetual Planet), this increases the potential for sublimation and reduces potential for melting..
Elevation of the snow line on Everest region glaciers determined from Landsat images of 10/13/2020, 1/17/2021, 10/22/2023 and 1/10/2024.
View of Lago Guillermo in true color Sentinel 2 images from Dec. 31 2023 and Jan 12 2024. Illustrating drainage of Lagor Guillermo (LG). Revealing more of the Peninsula (P). Upsala Glacier (U) had impounded this lake since formation by 1957.
Lago Guillermo draining during early January 2024 as revealed by Landsat images. Notice inlet left dry at Arrow 1, Arrow 3 ad Arrow 4. New islands at Arrow 2.
Lago Guillermo developed by 1957 as Upsala Glacier, Southern Patagonia Icefield retreated (Warren et al 1995). By 1999 a peninsula was evident extending south into the lake from the glacier terminus, see Landsat images below. By 2016 this peninsula was km long. Due to retreat and thinning of Upsala Glacier leading to detachment of Bertacchi Glacier in 2021/22 (Pelto, 2022), the ice dam impounding this lake has bee reduced. . Malz et al (2018) indicated a 3.3 m thinning of Upsala glacier with significant thinning extending to the Viedma Glacier divide. On Dec. 31-2023 the lake looks essentially as it has since 2016. By Jan 12. 2024 the lake had drained significantly leaving the ice margin for the first time in over seventy five year not terminating in the lake (arrow 4). The eastern terminus is now on land. The lake drainage exposed several islands within the lake (Arrow 2-Arrow 3). Led to drainage of the southern inlet at Arrow 1. Between 12-31-2023 and 1-15-2024 Lago Guillermo declined from 16 km2 to 10 km2 in area.
Recent retreat has exposed some interesting fossils around Lago Guillermo!
Upsala Glacier (U) in Landsat images from 1999, 2016 and 2023 illustrating both retreat and the separation from Bertacchi Glacier (B). Cono Glacier (C) is the next tributary to the north, to the east the Peninsula (P) in Lago Guillermo has grown as the lake has expanded.
The summer of 2023 was our 40th field season observing the response of North Cascade glaciers to climate change. Each year we visit a series of glaciers on the same date to complete our annual examination. We carry all of the equipment to each field site in backpacks and camp in tents near the glacier. All the glaciers we observe, except Easton Glacier, are in Wilderness Areas. This precludes the use of mechanized equipment or leaving instruments behind. We work each day in almost any weather conditions, and in the last decade that means dealing with forest fire smoke, only a few days have forced us to remain in our tents. We have covered over 5,000 miles, completed over 40,000 measurements and spent 800 nights in tents during the course of this research project. Three of the glaciers we observe are World Glacier Monitoring Service reference glaciers (42 in the world).
The field team consisted of Jill Pelto (Art Director), Mauri Pelto (Science Director), Julia Ditto (Field Artist), Mariama Dryak (Field Scientist-Team Logistics), Kai Yuan Wang (Field Scientist) Muruganandham Shivaprakesh (Field Scientist). For the third straight year conditions were poor for the glaciers. The 2021-2023 period was the worst three year stretch during the last 40 years with glaciers losing ~5-6 m of thickness, which is 10-20% of glacier volume depending on the glacier.
“40 Years in the North Cascades” by Jill Pelto. This painting is an emotional piece for me. It is an updated version of the very first data-art painting I created when I came up with the idea in 2015. The top surface of the mountain glacier is a line graph that depicts the mass balance of North Cascade glaciers in Washington state from 1984-2022.
We have observed the loss of three of our key glaciers we monitor, every glacier in the range has experienced significant retreat, and volume loss. Our mass balance observations indicate an average loss of 27 m water equivalent, ~30 m in thickness and ~35-40% of the entire volume of the glaciers in the mountain range lost. The summer of 2023 had the largest loss of glacier area of any of our 40 years, average terminus retreat exceeded 25 m. Ice Worm Glacier ceased to be an active glacier, joining a rapidly growing list of glaciers that are no more. The glaciers on Mount Daniel/Hinman in particular collapsed. The main variable we measure to determine glacier health is mass balance, the difference in snowfall gain vs. melt each year. The result of three bad years in a row 2021-2023, with losses exceeding -1.5 m led to this rapid retreat. The extent of blue ice was the highest we have observed on both Mount Daniel (95%) and Mount Baker (70%). This made traversing the glaciers more challenging. The added newly deglaciated unstable terrain also added challenge in accessing the glaciers.
Sholes Glacier is on a ridge extending northeast from Mount Baker and is at the headwaters of the North Fork Nooksack River. With the Nooksack Tribe we measured glacier runoff below this glacier from 2012-2021. The glacier mass balance is 24.5 m, with 2023 comprising 10% of that. The glacier has lost 10 m of thickness in the last 5 years, driving a rapid increase in retreat rate and opening a large ice cave near terminus.
Columbia Glacier is a cirque glacier at the headwaters of the North Fork Skykomish River. It is fed by avalanches mainly from the west side (left in images). The glacier retreat has accelerated in the last decade exposing a growing new lake. By 2023 the glacier has lost 40% of its volume since 1984. This is a World Glacier Monitoring Service reference glacier, one of 42 in the world. The slopes above the glacier have lost considerable perennial snowpack leaving much deeper depressions/basins that must be filled in the winter before avalanching commences. This has reduced the input of avalanches for the glacier.
Rainbow Glacier is on the northeast side of Mount Baker and is a valley glacier that feeds Baker Lake. The glaciers starts at 2100 m at a junction with the Park and Mazama Glacier. This is a WGMS reference glacier. The glacier mass balance loss has been 19.8 m, the slowest rate of any of the glaciers. The terminus has retreated 850 m.
Lower Curtis Glacier is a cirque glacier on Mount Shuksan. The glacier is avalanche fed and feeds Creek and then Baker Lake. The glacier has a steep seraced thick terminus front that reduces retreat rate, though this icefall has thinned rapidly in the last 5 years. Retreat has been 180 m since 1984, but will continue to increase due to the rapid thinning. Mass balance loss of 29.9 m is leading to significant marginal recession too.
Easton Glacier is a slope glacier on the south side of Mount Baker. The glacier feeds into Sulphur and Rock Creek and then the Baker River system. Sulphur Creek is diverted into Baker Lake. This is a WGMS reference glacier and has a mass balance loss of 24 m since 1990. The retreat of this glacier from the 1955-1980 period of advance was minor until 1992. Since then the retreat has been 570 m, including 100 m in the last two years.
Field team standing at the 2022 terminus location of Easton Glacier looking at one year of retreat on August 11, 2023.
Ice Worm Glacier is a small cirque glacier on the east side Mount Daniel feeding the Cle Elum River. The glacier has been retreating rapidly both at the terminus and at its head. The rapid area thinning and retreat from 2021-2023 resulted in many stream channels in the glacier reaching bedrock. The glacier mass balance has been -31.3 m since 1984, which is about 80% of its initial volume. Depth to bedrock is typically 4-6 m. The area of this glacier has dropped to 40,000 m² and it is no longer moving. Hence, this is now just relict ice, not an active glacier.
Daniels Glacier is a small slope glacier on the east side Mount Daniel feeding the Cle Elum River. The glacier dominated the east side of Mount Daniel in 1984, but now only 30% remains. Rapid mass loss of 27.5 since 1984 is leading to continued rapid disintegration of this now thin glacier. We observed many crevasses reaching bedrock even well above the terminus in 2023.
Lynch Glacier is on the northwest side of Mount Daniel at the headwaters of the South Fork Skykomish River. In 1984 the lake below was pea soup colored and filled with icebergs. Now it is a deep azure blue. The glacier has lost 25.4 m leading to rapid disintegration of the western side of the glacier. The steep thick terminus ending in the lake has retreated more slowly than other glaciers, but the volume loss has been similar.
In our camp on the North side of Mount Baker after a day on Rainbow Glacier, looking for mountain goats.
The Triplets and Cascade Peak glacier in GLIMS glacier viewer with the red outlines of the 1958 and 2015 margins and the black dot indicating they are now extinct.
In a 1993 Washington Geology article I noted that “In the Cascade Pass area two small glaciers in Torment Basin and two beneath the Triplets Peak and Cascade Peak have altitude ranges of less than 150 m. These glaciers in 1985, 1987 and 1992 were entirely in the ablation zone if present conditions persists they will disappear.” This is an update on the glaciers below The Triplets and Cascade Peak. The threshold for a glacier to exist in terms of area is typically 50,000 m² or 10,000 m², there must also be motion which is increasingly rare as area drops below 50,000 m² (Leigh et al 2019). Motion is typically determined by active crevassing, which does not include relict crevasses reaching bedrock (Fountain et al 2023). To survive a glacier must have a persistent accumulation zone, the lack of this leads to thinning of the glacier even in its upper accumulation area (Pelto, 2010).
The Triplets and Cascade Peak glacierwith plentiful active crevassing in 1986 image I took from near Cascade Pass.
The Triplets and Cascade Peak glacier with significant retained snowcover in 1990 image I took from near Cascade Pass.
In 1986 I first walked on the two glaciers below The Triplets and Cascade Peak. They were crevassed glaciers fed on north facing benches below the peaks providing good radiational shading and fed by avalanches. The glaciers are also steep enough to shed avalanches. In 1992 these two glaciers did not retain significant snowpack and we noticed some crevasses within 50 m of the ice front reaching bedrock. Of more import was that several sections of glacier with bedrock reaching crevasses had slid detaching from the glacier on the steep smooth bedrock glacier bed.This process of melt driven thinning leading to detachment of small glacier sections is what prompted me to think these glaciers would not last. This type of detachment is evident in the 1998 Google Earth image, lower right of Cascade Peak Glacier.
The Triplets and Cascade Peak glacier with limited snowcover on Triplets glacier even in early August 1992. We were on route to the glacier when I took this picture.
Crevasse on Triplet Glacier that reaches bedrock near terminus in 1996.
The Triplets and Cascade Peak glacier with active crevassing in 1998 Google Earth image (yellow arrows). Some of these crevasses reached bedrock and led to detachments, note lower right on Cascade Peak glacier.
The Triplets and Cascade Peak glacier with active crevassing in 2003 with developing separation between east and west sections at yellow arrows.
The Triplets and Cascade Peak glacier with active crevassing only on Cascade Peak glacier in 2016 Google Earth image (yellow arrow).
In Sept 2023 The Triplets is now six fragments Cascade Peak glacier is three fragments. Image from Wyatt Mullen, who shares spectacular images on Instagram daily.
From 2003-2005 each summer these two glaciers failed to retain much snowpack and continued to thin and lose area. The Global Land Ice Measurements from Space (GLIMS) assessed the The Triplets and Cascade Peak glaciers with an areas of respectively 55,000 m² and 60,000 m², respectively this area was updated with a 2015 area assessment of 70,000 m² and 32,000 m² respectively. In 2019, 2021, 2022 and 2023 glaciers in the North Cascades experienced a sequence of years that left most glaciers in the range largely snow free for the last 4-6 weeks of the melt season leading to exceptional mass loss and consequently area loss. The area of the largest contiguous area of ice of the two glaciers declined from 51,000 m² and 31,000 m² in 2019, to 37,000 m² and 26,000 m² in 2021 and 18,000 m² and 15,000 m² in 2023. By 2023 neither glacier exhibited active crevassing as both approached the lower threshold for glacier existence. Thirty years after my initial assessment both The Triplets and Cascade Peak glaciers no longer exist. This is shown in the GLIMS glacier viewer which illustrates extinct glaciers as black dots. These two are in the list of 34 extinct glaciers in the North Cascades that I have measured since 1984 that are now gone, and are in this GLIMS extinct glacier layer. The sustained mass balance loss of North Cascade glaciers is what is leading to significant volume declines of all glaciers and loss of glaciers that were thin (Pelto, 2018).
The Triplets and Cascade Peak glacier in August 2019 Sentinel false color image. Area of The Triplets glacier =51,000 m²: Cascade Peak glacier=31,000 m²
The Triplets and Cascade Peak glacier in August 2021 Sentinel false color image. Area of The Triplets glacier =37,000 m²: Cascade Peak glacier=26,000 m²
The Triplets and Cascade Peak glacier in August 2023 Sentinel false color image. Area of The Triplets glacier =18,000 m²: Cascade Peak glacier=15,000 m²
The Triplets and Cascade Peak glacier with significant retained snowcover in 1990 image I took from near Cascade Pass.
From a Glaciers Perspective 