The retreat of the main outlet glaciers of Cook Ice Cap is evident in the Landsat images from 2001 (red arrows) to 2025 (yellow dots). Dumont D’Urville Glacier=-1.5 km, Vallot Glacier=-2.4 km, Naumann Glacier=4.0 km, Ampere Glacier=-3.3 km and Diosaz Glacier=-0.8 km.
Kerguelen Island is at the edge of the furious fifties in the southern Indian Ocean. The island is host to many glaciers, the largest being the Cook Ice Cap at 400 km2. A comparison of aerial images from 1963 and 2001 by Berthier et al (2009) indicated the ice cap lost 21 % of its area in that period. The east side of the Cook Ice Cap outlet glaciers tetreat has led to formation and expansion of a new group of lakes (Pelto, 2016). Here we examine the changes from 2001-2025 along using Landsat and Sentinel imagery.
Ampere Glacier main terminus retreated 800 meters from 2001-2011. Here the terminus has pulled back from the tip of the peninsula on the west side of the terminus and is currently at a narrow point. The eastern terminus has retreated to its junction with the main Ampere Glacier a distance of 1400 m. From 2011 to 2025 the retreat accelerated totalling 3.3 km by 2025. The glacier had two nunataks L and N in 2001, by 2025 L has emerged as a marginal mountain and N is barely surrounded by ice.
Diosaz Glacier retreated 0.8 km from 2001-2025 leading to a small new lake basin developing.
Naumann Glacier retreat has been 4.0 km from 2001-2025 creating an new alpine lake. With the glacier no longer terminating in the lake retreat should slow.
Vallot Glacier has retreated 2.4 km creating a new alpine lake at its southern terminus. The glacier will have just one terminus in the near future and the two lake basins could merge.
Dumon d”Urville Glacier has retreated 1.5 km with the lake it terminates in developing an expanding southern embayment.
The east side of the Cook Ice Cap on Kerguelen Island outlet glaciers retreatn and expanding group of lakes illustrates widespread ice cap thinning (Pelto, 2016). Verfaillie et al (2016) identified that the accelerating glacier wastage on Kerguelen Island was due to reduced net accumulation and resulting rise in the transient snowline since the 1970s, when a significant warming began.
Cook Ice Cap in 2011 Landsat and 2017 Sentinel image. Red arrows indicate 2001 terminus positions and orange dots the 2011 terminus position.
Volcan Peteroa at 35 S straddles the Argentina-Chile Border. Its glaciers-Azufre and Penon have been nearly snow free since mid-January 2026with 5% snowcover on Feb. 16, 2026. These glaciers drain into Rio Colorado and then the Rio Lontue River of Chile.
The summer of 2026 has led to high snow lines and many snow free glaciers in the Central Andes of Argentina and Chile. This follows the pattern observed in 2022, 2023 and 2025 of limited retained snowcover (Pelto, 2025). To be in equilibrium a glacier needs to have 50+% snow cover at the end of the summer. When an alpine glacier such as this loses essentially all snow cover, glacier wide mass balance loss is at least 2 m,. This equates to more than 2 m of thinning on average across the entire glacier.
The Glambie Team (2025) found the southern Andes lost 12.8% of their total mass from 2000-2023. Ayala et al (2025) identified that from 2000-2019 Central Andean glaciers were able to buffer drought conditions in this region. Annual precipitation was 36% below average in this period yet streamflow was essentially maintained. Continued area loss since 2019 is and will lead to ongoing summer runoff declines. This impacts down stream hydropower, aquatic life and agriculture.
From 33 S at Olivares Alfa, to 35 S at Volcan Peteroa False Color Sentinel images illustrate the lack of snow cover in Janurary leading to less than 5% retained snow cover for each of these four glaciated areas.
Cobre Glacier, Argentina flows east from the border. It’s snow cover declined from 20% on Jan. 22, 2026 to 5% on Feb. 18, 2026.The glacier continues to retreat rapidly, the glacier reached the lake at lower right in 2016.The glacier drains into the Rio Grande River.
Humo Glacier and Fiero Glacier, Argentina had 20% snow cover on feb. 18, 2026 declining to 5% snow cover on March 12, 2026. It drains into Lago Atuel and is one of the headwaters of Rio Atuel. Rio Atuel has hydropower development above and within the Rio Atuel Canon including Nihuil dam above the canyon and four more dams within the canyon, including Valle Grande Reservoir.Olivares Alfa Glacier and Paloma Norte Glacier, Chile had less than 10% snow cover on Feb. 16, 2026 declining to less than 5% on March 13, 2026.The glaciers are at the headwaters of the Olivares River, which drains into the Coloardo River. The Alfalfal Hydropower Plant is on the Colorado River.
Glaciar Mayo terminus change from November 2025 to February 2026 illustrated in Sentinel images. The yellow dots indicate the margin, which has retreated on both sides forming a melange (M) and new icebergs (I).
Glaciar Mayo, Argentna in Los Glaciares National Park is an eastern outlet of the Southern Patagonia Ice Cap. The glacier has terminated on the northern shore of a glacial lake for the last ss years. The mass balance from 1975-2011 was identified as slightly positive by Schaefer et al (2015). This enabled the glacier to terminate on the northern shore of a glacial lake, an arm of Lago Argentino from 1984-2020. From 2000-2019 Minowa et al (2021) noted that Glaciar Mayo had transitioned to a negative balance and overall thinning. This thinning is what has led to the terminus beginning to collapse into the lake.
The terminus tongue projecting into the lake had been 2.5 km2, had now declined to 1.4 km2. The terminus along the northern shore had been 2000 m wide and is now 1150 m wide. There is further crevassing/rifting that suggests the glacier tongue is not done thinning in 2026. This continues to be an active year for calving retreat in Patagonia as seen at Upsala and Jorge Montt Glacier, see below.
Glaciar Mayo terminus change from November 2025 to February 2026 illustrated in Landsat images. The yellow dots indicate the margin, which has retreated on both sides forming a melange (M) and new icebergs (I).Jorge Montt Glacier retreat from 2021-2026 with a particularly extensive and packed melanage in 2026, observed in Sentinel images.Upsala Glacier had a burst of calving in Feb. 2026. The comparison to 2021 highlights both the retreat, separation from Bertachhi Glacier and substantial drainage of Lago Guillermo.
Grasshopper Glacier in 2025 Sentinel image with almost no relict ice remaining. To the northwest Wolf Glacier is still an active glacier.
Grasshopper Glacier, Montana is in the Beartooth Range in Custer National Forest. The glacier occupies a north facing cirque at nearly 3300 m on Iceberg Peak (11,000 ft.). The name of the glacier is derived from the millions of grasshoppers that were discovered embedded in the ice in 1898 by Dr. James Kimball. He estimated their were thousand of tons of grasshoppers in the ice. Nearly a century later some of these grasshoppers were extracted from the glacier and using radiocarbon dating scientists the remains of these grasshoppers finding they had been trapped in the 1300s (Sutton et al, 1996). These grasshoppers either were downed by a sudden storm or were carried over the glacier by strong winds aloft, and then cold forced them onto the ice surface. The grasshoppers are an extinct type of Rocky Mountain grasshoppper Melanoplus spretus (Lockwood et al., 1992)
Grasshopper Glacier from the 1966 USGS map, north is at the bottom of this image.
In 1940 the glacier was ~1.6 km. wide and on its northwest side terminated in a 15-m. cliff in a small lake. In 1966, see map below, glacier had an area of 0.42 km2, with a small lake present. The glacier lost 50% of its area and 90% of its volume between the Kimball visit in 1898 and Jane Ferrigno visiting in 1981 (Ferrigno, 1981). In 1981 the upper and lower sections of the glacier are still connecterd, with the bench between them not yet exposed.
Grasshopper Glacier in 1981 illustrating a concave slope, and continuous slope from lake to upper glacier.
By 1994 the area had decline to 0.26 km2. The bench between the upper and lower section of the glacier is emerging and the lake has expanded to 0.08 km2.
Grasshopper Glacier in 1994 Digital Globe image, with red outline indicating 1966 margin. North is at bottom of image. The lake has exapnded substantially.
By 2005 the glacier has separated into a upper portion just below the peak and a narrow section extending to the lake. There is a single crevasse near the ice front. By 2005 this glacier has ceased to exist as an active glacier, there are a few remnant perennial snow and ice patches the largest with an area of 0.05 km2. In the majority of recent summers the glacier has lost all of its snowcover. Glacier survival is dependent on consistent accumulation retained on the glacier each summer, this glacier will not survive.
In 2015 the lower section no longer reaches the lake, and there are no longer any crevasses. The area of the upper section is 0.025 km2. The concave profile, limited area and lack of crevasses indicates this is no longer a glacier.
Grasshopper Glacier in 2005 and 2015 Digital Globe images illustrating the loss of glacier ice reaching the lake. The upper section below Iceberg Peak still has relict ice.
Grasshopper Glacier in 2001 with a few crevasses near the ice front (A.Lussier Image).
The glacier has continued its rapid recession and the further segmentation into small disconnected segments, heralds the end this glacier. We do have a gorgeous new alpine lake in its place. Notice the basin is still largely devoid of plant life, which is red in this false color image. The surface still has the color of newly exposed-deposited sediments. It is interesting that the glacier was named for a type of grasshopper that went extinct in the late 1800s in conjuction with the expansion of farming in the midwest, that disrupted their life cycle. Now the glacier is gone due to the warming climate from our increased production of carbon dioxide.
Novosilski Glacier (N) on the west coast, Risting Glacier (R) in Drygalski fjord, Salomon Glacier (S) on the south shore, Twitcher Glacier (T) in Twitcher Bay and Hindle (Hi) and Ross Glacier (RO) in Royal Bay eachexperienced a detachment (D) from a tributary glacier due to glacier retreat from 2016 to 2016, as noted in these Landsat images.
South Georgia Isalnd is a notoriously cloudy location. A remarkably clear Landsat image from Jan. 21, 2026 provides a good snapshot of glacier change since a similarly clear day on February 19, 2016. Here we examine several glacier near the southern tip of the island that have experienced retreat leading to glacier detachment. Pelto (2017) documented the retreat of 11 of these glaciers during the 1989-2015 period. I worked with NASA Earth to document the retreat of some east coast glaciers evident in Landsat images at that time. BAS map provides context on wildlife populations and glacier retreat.
Novosilski Glacier (N) in 2016 is still connected to Tributary 1. By 2026 tributary 1 is separated from the main glacier due to a 1.3 km retreat.
Novosilski Glacier is a large tidewater outlet glacier on the west (cloudier) coast of South Georgia terminating in Novosilski Bay It shares a divide with the rapidly retreating Ross and Hindle Glacier on the east coast. The glacier retreated 1.3 km from 2020 to 2026 leading to Tributary 1 no longer connecting to the main glacier.
From 2016 to 2026 Ross Glacier retreated 2.5 km and Hindle Glacier 1.6 km. The Hindle retreat led to Tributary 1, 2 and 3 all detaching from one another.
For Ross and Hindle Glacier in 1989 the glaciers joined 2.5 km from the terminus spanning Royal Bay with a 3.2 km wide calving front. By 2001 the glacier front had retreated 800 m, but was still a single joined calving front. By 2009 the glaciers had separated due to an additional retreat of 1.4 km. The Hindle Glacier front was now retreating south up opening a new separate fjord from Ross Glacier. The calving front in 2009 was 1.6 km wide. By 2015 a 1.6 km retreat led to the separation of Hindle from Tributary 4. From 2016 to 2026 a further 1.6 km retreat to the approximate head of the fjord led to separation of Tributary 1, 2 and 3. Ross Glacier retreated 2.5 km from 2016-2026 without separating from any tributary.
A 1 km retreat of Risting Glacier (R) led to Tributary 2 detaching from the Tributary 2 and 3 between 2016 and 2026,
Risting Glacier terminates in Drygalski Fjord on the southeast coast of South Georgia. Risting and Jenkins Glacier were joined until the 1980’s. Cook et al (2010) note the glacier had a relatively uniform retreat rate from 1955-1999 of 40 to 50 meters/year, with retreat increasing after 2000. From 2002-2016 Risting Glacier retreated 1100 m, a rate of ~80 m/year twice the 1955-1999 rate. From2016-2026 the glacier retreated another 800 m, continuing at the same rate. This led to detachment of tributary 1 from the rest of the glacier.
Twitcher Glacier (T) retreated 3.7 km from 2016 to 2026 leading to detachment of Tributary 1.
Twitcher Glacier is the next glacier south of Herz Glacier (H) on the east coast of South Georgia. Until 1989 the glacier ended at the tip of a peninsula that separates it from Herz Glacier., the ensuing retreat has led to the opening of a new fjord. By 2015 the glacier has retreated 2.2 km. An accelerated retreat from 2016-2026 of 3.7 km led to separation from Tributary 1.
The story is the same from glacier to glacier with extensive retreat leading to tributaries detaching from each other. These glaciers still maintain snow cover across a significant area of the glacier and can survive current climate.
Videla Glacier, Chile is an outlet glacier of the Cordillera Darwin Icefield. The glacier has a number (Point 1-6) of terminus lobes where retreat has led to proglacial lake development between 1997 and 2025, as seen in these annotated Landsat images.
Videla Glacier is a land terminating glacier in the northwest portion of the Cordillera Darwin Icefield (CDI) in Tierra del Fuego, Chile. The glacier has terminates in several expanding proglacial lakes each in front of a different tongue of the glacier. The glacier flows northwest from Cerro Ambience towards Fiordo Profundo. Meier et al (2018) identified area change of Patagonia glaciers from 1870-2016 with a ~16% area loss of CDI, with more than half of the loss occurring since 1985. They also noted that CDI glaciers were retreating fastest between 1986 and 2005. Izagirre et al (2025) identified a 124% increase in glacier lake area from retreat between 1945 and 2024. The retreat has been largest on tidewater glaciers such as Marinelli Glacier and Ventisquero Grande Glacier.
In 1997 of Videla Glacier’s six main terminus lobes, five did not exhibit a proglacial lake, only the two northern most lobes (Point 4, 5, and 6) ending in a fringing yet to develop proglacial lake. The terminus lobes at Point 2 and 3 were joined. By 2019 lobes 1 and 4 had developed significant proglacial lakes, while the main terminus at Point 5 and 6 had opened up two halves of the same proglacial lake. The terminus lobes at Point 2 and 3 had separated. A rib (yellow arrow) was developing upglacier of the main terminus indicating thinning and reduced flow. A new lake had developed just downstream of this rib.
In 2025 the terminus at Point 1 had receded 950 m creating a 0.75 km2 proglacial lake. Terminus Lobe 2 and 3 had separated by 400 m. At Point 4 a 0.5 km2 proglacial lake had formed with the 1050 m retreat. The main terminus at Point 5 and 6 extends across the lake basin in a narrow 350 m wide tongue. The lake has grown to 3 km2, with 1.5 km of recession from Point 6 and 1.8 km from Point 5. This narrow tongue may well break off this coming summer.
Videla Glacier, Chile ongoing retreat and proglacial lake growth at terminus lobes (1-6) illustrated by Landsat images from 2019 and 2022.
HPS-12 Glacier in 1985 and 2017 Landsat images. The red arrow indicates 1985 terminus, yellow arrows the 2017 terminus, purple dots the snowline and 1-4 are tributaries. By 2017 all tributaries have detached and the glacier has retreated 13 km.
HPS-12 is an unnamed glacier draining the west side of the Southern Patagonia Ice Cap (SPI). The glacier terminates in a fjord and is adjacent to Upsala Glacier to the east and Pio IX Glacier to the north. This developing fjord is also unnamed but feeds into Estero Falcon. Here we update the 2017 NASA Earth Observatory project I completed in 2017, that identified this as the fastest retreating glacier in Chile in the 1985-2017 period, using Landsat imagery from 1985-2025.
HPS-12 Glacier in 2015 and 2025 Landsat images. The red arrow indicates 1985 terminus, yellow arrows the 2025 terminus, black arrow the 2015 terminus. Former tributary 1 and 2 have declined in width .
In 1985 the HPS-12 terminates 1.5 km from the junction of two fjords that are occupied by HPS-12 and HPS-13. These are separated by a peninsula. The glacier is fed by four tributaries labelled 1-4. The snowline in 1985 is at 900 m. In 2001 the four tributaries still join the main glacier, but the terminus has retreated 3.5 km. In 2015 glacier retreat has led to separation of tributary 1, 2 and 4 from the main glacier, tributary 3 only feeds tributary 2 and not the main glacier. The glacier retreat has continued to 2017, the current terminus is 800 m wide vesus 2800 m wide in 1985 . Total retreat from 1985 to 2017 was 13 km. By 2025 the glacier has retreated 14.75 km and has lost more than 50% of its total length. Tributary 1 and 2 continue to narrow from 2015 to 2025 illustrating that flow from the icefield accumulation zone is being reduced. This suggests less discharge into the terminus reach of HPS-12.
This glacier follows the pattern of retreat we have reported from Bernardo Glacier, O’Higgins Glacier, Tyndall Glacier and Upsala Glacier. The retreat is driven by the SPI have been experienced significant mass loss a. Malz et al (2018) noted a ~1 m/year mass loss from 2000-2016 with HPS-12 and Jorg Montt Glacier losing the most. Minowa et al (2021) found that 35% of all ablation of the Patagonia Icefields stemmed from frontal ablation.
HPS-12 Glacier in 2001 and 2015 Landsat images. The red arrow indicates 1985 terminus, yellow arrows the 2017 terminus, purple dots the snowline and 1-4 are tributaries. By 2015 tributaries 1, 2 and 4 have detached.
Bonnet Glacier in Banff National Park in the 9-5-2025 Sentinel image has lost its snow cover in 2025. This is causing rapid expansion of bedrock amidst the glacier as the glacier thins (yellow arrow).
The summer of 2025 featured extensive melt on Alberta glaciers in many cases removing all snow cover. A glacier that cannot retain snow cover is akin to a company have no income, only expenditures for the year. If this trend persists the glacier will not. This builds on a period of glacier loss in the region from 2011-2020 glacier loss accelerated by ~190% from the 1984-2010 period in this region (Bevington and Menounos, 2022). The 2021-2024 period was noted as a period of unprecedented ice loss in Western Canada (Menounos et al 2025). Haig Glacier has been a summer training ground for cross country skiers. This summer by mid-August snow cover was too limited to permit this use, which had happened in 2023 as well. The result in the images below of rapid melt is fragmentation, bedrock emerging amidst glacier and glacier area decline. Here we examine a series of glaciers within 100 km of Banff, Alberta in Sentinel images from September 2025.
Haig Glacier on 9-2-2025. This glacier in Peter Lougheed Provinicial Park has only a sliver of snowcover at the very top of the glacier.Petain Glacier in Height of the Rockies Provincial Park has a fringe of snow cover left at the top of the glacier in mid-September. The thinning glacier has bedrock emerging amidst the glacier.Icefall Mountain Glacier on 9-5-2025 has lost all snow cover. This glacier in Siffleur Wilderness Area features expanded bedrock areas amidst the glacier (yellow arrows).Trifid Glacier in Banff National Park lost its snowcover and is continuing to fragment in this false color Sentinel image.Drummond Glacier in Banff National Park in early September 2025 has lost 96% of its snow cover this is leading to fragmentation of the glacier.
Willingdon Glacier in Siffleur Wilderness Area lost all but a sliver of snow cover in 2025. The rapid thinning bare glacier ice is leading to fragmentation at yellow arrow.
Rikeva Glacier retreat in Landsat images from 2020 and 2025. Illustrates new island at Point A and retreat of land terminus at Point B and from headland at Point C.
Rikeva (Rykacheva) Glacier flows from the Northern Novaya Zemlya Ice Cap to the west coast and the Barents Sea. The glacier has been retreating rapidly like all tidewater glaciers in northern Novaya Zemlya (Pelto, 2016) (Carr et al 2014) identified an average retreat rate of 52 m/year for tidewater glaciers on Novaya Zemlya from 1992 to 2010. Maraldo and Choi (2025) identified frontal retreat rate of Novaya Zemlya glaciers from 1931-2021 and found an increased each decade since the early 1970s, reaching a peak retreat rate of 65 m/year between 2011 and 2021. We have observed the impact at Vilkitskogo Glacier and Krayniy Glacier,
In 2000 Rikeva Glacier extended beyond the island that would emerge at Point A. The landbased terminus lobe extended just beyond Point B. By 2013 the glacier had retreated adjacent to the island, with the island acting as a stabilizing point for the terminus. The terminus lobe had retreated just south and east of Point B.
Rikeva Glacier in Landsat images from 2000 and 2013 illustrating retreat to island at Point A and retreat of land terminus at Point B.
In 2018 Rikeva Glacier terminus rested on an island at Point A that acted as a buttress for the glacier terminus. By 2025 the glacier had retreated from the island with 4.5 km2 of glacier retreat since 2018 and 8 km2 of retreat since 2000.
Rikeva Glacier in Sentinel images from 2018 and 2025 illustrates retreat from Island at Point A.
Macbeth Icefield, BC in false color Sentinel image from 9-25-2025. Bare of snow cover reveals annual layers within firn, darkened by dust and forest fire partical deposition.Small glaciers A,B,C and E have vanished.
Macbeth Icefield is the Purcell Mountains of southwestern British Columbia. The several icefield outlet glaciers drain into Duncan Lake the Duncan River and then Kootenay Lake. From 2011-2020 glacier loss accelerated by more tha 250% from the 1984-2010 period in this region (Bevington and Menounos, 2022). The 2021-2024 period was noted as a period of unprecedented ice loss in Western Canada (Menounos et al 2025). The summer of 2025 was even worse. Access to the Macbeth Icefield Recreation Area is currently closed due to extensive forest fire impact to the long hiking trail that accesses the icefield (images below illustrate the burn scars).
I have had the opportunity to review satellite images of this area from 1984-2025. In 2025, for the first time the icefield lost all snow cover exposing many annual layers of firn. The firn is snow that endured at least one summer, and is not yet converted to glacier ice. This firn is signficantly darkened by particles of dust and forest fire derived material. This further enhances melt once exposed.
In 2023 and 2024 significant firn areas were exposed as well, in the sequence of images below. . The repeated years of limited snow cover has led to mass balance loss and a 25-30% reduction in icefield area since 1987. From 1987-2025 several small adjacent glaciers have been lost A,B, C and E. t Point D the glacier has fragmented. At Point F the glacier ended in the lake in 1987 and now the glacier has retreated 700 m from the lake.
Macbeth Icefield in 1987 and 2025 Landsat images indicating recession of icefield margin, loss of snowcover and vanished small glaciers A,B,C and E.A 2024 forest fire burned extensive areas in the Birnam Creek valley that drains the southern end of the icefield. The 2023 image illustrated the consistent red of forest, with the brown areas at the yellow arrows indicating burn scars.Macbeth Icefield in Sentinel image from 9-1-2023. Extensive firn area is exposed, while 30% of the icefield has retained snow cover.Macbeth Icefield in Sentinel image from 9-5-2024. Extensive firn area is exposed, while 20% of the icefield has retained snow cover.Macbeth Icefield in Sentinel image from 9-25-2025. The lack of snow cover is evident.
Silver Star Glacier image from August 18, 2025 indicating no retained snow cover. Ilustrates the glacier still has crevasses.Below is June 2025 image from Jack McLeod that illustrates detachment occuring in upper portion.
The USGS (1971) North Cascade glacier Inventory identified 15 perennial snow/glacier areas in the Methow Valley from 1958 aerial images. To qualify for the list you needed an area of 0.1 km2. There were three glaciers on Tower Mt., two on Golden Horn, two on Gardner Mt., two on Robinson Mt. and 5 on Silver Star Mt. When we began annual field monitoring of North Cascade glaciers in 1984 we explored the identified glaciers around Tower Mt. and Silver Star Mt. The northeast side of Tower Mt. still had one existing glacier and Silver Star Mt. had three.
Tower Mountain in 2025 illustrating the loss of glaciers at the three locations that had hosted glaciers in 1958.
As of 2005, I could identify 9 glaciers with an area of 0.8 km2, in the Methow Valley. About 30% of this area was on Silver Star. On Silver Star there were 3 glaciers in 1958 with a combined area of 0.33 km2. Silver Star had three identified glaciers in 1958. With the western most being the most extensive. The middle and western Silver Star Glacier had crevassing. The eastern Silver Star Glacier was a perennial snow field with no crevassing and insufficient thickness and size to generate movement.
Silver Star Glacier from Aug. 28 2006. The glacier is snow covered above the main icefall.
In 2006 here were two glacier left with an area of 0.19 km2 . In this area average July-Sept. ablation on the glacier is 2.6 m/a. Thus, an area of 900,000 m2 x 2.6 m =2.34 million m3 of runoff from the glaciers on average contributed to the Methow River system. This is down from 3.9 million m3 in the 1970’s. This is a significant amount of water, but based on the disappearance of Lewis Glacier, a 40% drop in runoff occurred from the glacier basin in July-Sept. after the glacier was gone. This indicates that approximately 60% of the runoff would occur from the snowpack in the former glaciated area. Thus, the loss of all glaciers will generate a loss of close to 1 million cubic meters for the basin during the July-Sept. period. This runoff would be released earlier in the melt season. Average July-Sept. flow at Winthrop was 750 cfs from 1990-2004, while the glacier runoff had declined to ~10 cfs .
In 2013 the western Silver Star Glacier still had active crevassing and does retain snow cover through the summer. The middle Silver Star Glacier was fragmented stagnant ice that indicated it may no longer have been a glacier. At that time I assessed it could not survive the next pair of warm years.
Silver Star Glacier in 2014 illustrates that is still an active glacier with significant crevassing. This image is taken from lower west margin by Fritz Stugren.
The lone remaining glacier is confined to a narrow chute is 750 m long, and no more than 200 m wide. There is a small icefall. This glacier is similar to the upper east side of Lynch Glacier, if that was the only part. The glacier is retreating slowly 75 m from 1993 to 2013.
In 2025 the western Silver Star Glacier was 670 m long, an 80 m retreat since 2013, and has an area of 0.075 km2. The crevassing is noticeably reduced. The top of the glacier has several thin areas that will lead to detachment as illustrated by the Jack McLeod image. The glacier still has crevassing and areas likely over 30 m thick. This is the only remaining glacier in the basin and can survive another decade. During late summer periods the glacier provides between 1 and 2 cubic feet per second to the stream system.
The role glaciers play for rivers is buffering low flow periods late in summer. Without glaciers the late summer water supply diminishes. The trend in the Methow has been a sharp reduction in flow for June-August from the 1990-2004 period to the 2015-2025 period. Average discharge from July-September has fallen ~40% for the 2015-2025. In the Methow River valley supporting the reintroduction of beavers is a project that can buffer late summer streamflow to an extent. The Methow Beaver Project is well on the way in this effort.
Methow River mean monthly discharge at the Methow River at Winthrop, WA – USGS-12448500 station. The river has a higher peak discharge in spring now and and a much lower summer discharge.
Twins Glacier in Sentinel 2 images late in the melt season in 2021, 2023, 2024 and 2025. The darker blue is bare ice and the light blue is snow cover. This illustrates the lack of significant snow covered area each of these summers.
Twins Glacier in the Wind River Range of Wyoming is nestled on the north side of a ridge extending from Winifred Peak to The Buttress, in Titcomb Basin. Titcomb Basin is high alpine basin that lacks trees and has many alpine lakes. The basin was named for brothers Charles and Harold Titcomb, who were some of the first to explore the area in 1901. The Wind River Range was inhabited by the Sheepeater Shoshone (Tukudika) tribe as far back as 2000 BC. This tribe relied on bighorn sheep as a key staple and did not utilize horses, both adaptations useful for alpine terrain. Fur trappers were active in the region going back to the 1830s including Charles Fremont for which Fremont Peak on the east side of the basin is named. Titcomb Basin remains popular with climbers today.
Devisser and Fountain (2015) identified Wind River Range glaciers lost 47% of their area from 1900-2006. Li et al (2025) indicate a thinning rate of 0.58 m/year on Wind River Range glaciers from 2000-2019, representing a cumulative loss of 11.6 m. The loss from 1968-2000 had been -0.08 m/year. This accelerated thinning this century has led to rapid area losses across the range. The mean June-September temperature for the Wind River (Wyoming-Division 9) rose 1.2oC from 1900 to 2024. The mean June-September temperature exceeded 16.5oC five times from 1900-1999 and nine times from 2000-2025. During the 1900-2024 period there is no trend in November-April total precipitation for the Wind River Division. It is the frequent warm summers that have accelerated glacier loss.
Twins Glacier in 1966 spread broadly across the mountain slope from Knapsack Col to The Buttress and had an area of 0.49 km2 (GLIMS). The glacier extending close to the top of a rounded ridge does recieve wind enhanced snow deposition, but no avalanching. By 2015 the area had declined 75% to 0.13 km2 and was primarily confined to an area below The Buttress (Fountain et al 2023). The 2013 image (from Bob Sihler) below illustrates a lack of snow or firn cover which indicates there is no longer a persistent accumulation zone, without which a glacier cannot survive (Pelto, 2010). From 2021-2025 each summer the glacier has lost all snow cover indicating it no longer has an accumulation zone. This has led to rapid thinning and development of a bedrock ridge that has nearly separated the glacier, note 2021 image (from Will Wickert). In 2025 the glacier lost all snowcover and was fragmenting into two sections with an area of 0.05 km2 and 0.03 km2 respectively. The ~50 visible annual layers indicates ice in the glacier is all from the last 75 years. The glacier is almost disappeared. The fragmentation and acceleration of area loss indicates this glacier cannot endure several more years of warm conditions that eliminates snow cover.
Twins Glacier outline in blue on USGS map based on 1966 aerial photographs. Glacier extends from Knapsack Col to east end of The Buttress.
Twins Glacier in 2013 seen from the northeast nestled below The Buttress. The diagonal bedrock ridge that is now fragmenting the glacier is not yet evident. The lack of snow or firn cover illustrates the glacier is not retaining snow cover. This image taken by Bob Sihler.
Twins Glacier in 2021 indicating rock rib extending diagonally across the glacier. There is limited retained snow or firn cover with a month left in the melt season. There are ~50 visible annual layers. The thin nature of the glacier is also evident. This is an image taken by Will Wickert.
From a Glaciers Perspective 