Global Alpine Glacier 2025 State of Climate Report

On By mspeltoIn climate change glacier retreat, glacier climate change, Glacier ObservationsLeave a comment
Figure 1. Global mean annual balance (bars) and cumulative balance (line) from the WGMS data set.

Each year since 2008 I have been responsible for summarizing the global alpine glacier status for each specific year in the Bulletin of the American Meteorological Society State of the Climate report. The 2025 report came out in early August. Below is the report with several added figures.

The 2025 World Glacier Monitoring Service (WGMS) dataset of annual glaciological mass balance observations includes 162 glaciers from six continents and 26 nations, 158 with a negative balance and four with a positive balance. In 2025, the mean annual mass balance of the 59 reporting global reference glaciers was –1.34 m w.e., and -1.34 m w.e. for all 162 reporting glaciers. The 2025 regionalized global average annual balance of –1.09 m w.e., is the fourth consecutive year with mass balance loss exceeding 1.0 m w.e., 2023 had the most negative -1.23 m w.e and 2024 was at 1.04 m w.e. Since 1976, mountain glaciers and ice caps have lost 9179+621 Gt of water, contributing 25.3+1.7 mm to the global mean sea level rise, with 41% of this loss occurring in the last decade (Dussaillant et al. 2025).

The mean annual balance of global reference glaciers was -1.34 m w.e., a similar result to 2023 and 2024 with a mean annual balance for global reference glaciers of -1.60 m w.e. and -1.37 m w.e., respectively.  This makes 2025 the 38th consecutive year with a global alpine mass balance loss, the 16th consecutive year with a regionalized global mass balance below –0.5 m w.e. The significant acceleration of mass balance loss is evident in glaciological observations, geodetic observations, altimetry observations and gravimetric observations (The GlaMBIE Team, 2025). The acceleration of mass balance loss indicates glaciers are not approaching equilibrium and increasingly are disappearing. The Global Land Ice Measurement from Space inventory of global glaciers has now added an extinct glacier layer to record glaciers that have disappeared, that is populated by 181 glaciers that had existed in a previous inventory (Raup et al. 2025). In conjunction with 2025 being the UN International Year for Glaciers’ Preservation the Global Glacier Casualty List has been created to chronicle the story of specific glaciers being lost from each glaciated region (Boyer and Howe, 2025).

Hofsjokull eystri, Iceland was snow free by mid-August, leading to extensive ice cap thinning.

In the European Alps all 54 glaciers observed had negative balances, with 45 of the glaciers losing over 1 .0 m w.e. In Iceland (6) and Svalbard (9) all 15 glaciers observed lost over 1.0 m w.e. In Norway 8 of 10 glaciers had a negative balance, with two glaciers having a positive balance. In Sweden 3 of 4 glaciers had a negative balance.

High snow line on Durung Drung Glacier, India near end of summer monsoon season.

In Asia all 23 glaciers across 7 nations had negative balances averaging 0.97 m w.e. In New Zealand the glaciers observed had a negative mass balance.

Agua Negra Glacier, Argentina with minimal snow cover at end of summer melt season.

In the Andes Mountains of South America nine of ten, reporting from four nations, had negative balances, with an average balance of -0.92 m w.e.

All 14 glaciers in Western North America, outside of Alaska, had mass balance below -1.0 m w.e. with an average of -2.24 m w.e. Peyto Glacier, Canada exemplifies the limited retained snow cover on alpine glaciers in Western North America in 2025, a glacier should be 50-60% snow covered at the end of summer to be in equilibrium (Fig X2). It is evident Peyto Glacier is representative of adjacent glaciers that also have limited retained snow cover.  In Alaska 3 of 4 glaciers had negative balances. The five glaciers in Arctic Canada all had small negative balances averaging -0.16 m w.e.

Snow cover was minimal in the Yoho-Peyto Glacier regions, Canada at the end of the melt season.

Alpine annual mass balance glaciological observations are reported to the WGMS by National representatives with a December 1 annual submission deadline. WGMS reference glaciers (60) have at least thirty continuous years of mass balance observation. Benchmark glaciers (23) have at least a ten-year mass balance record and are in regions that lack sufficient reference glaciers. The combination of benchmark and reference glaciers are used to generate regional averages (WGMS, 2023). Global values are calculated using a single averaged value for each of 19 mountain regions, limiting bias from observed regions (WGMS, 2023). Expansion of this data set leads to reanalysis and updated values.

References

Boyer, D. and Howe, C. 2025. Communication efforts to educate the public about vanishing glaciers, 1958–2025. Annals of Glaciology, 67: e2. doi:10.1017/aog.2025.10033

Dussaillant, I., Hugonnet, R., Huss, M., Berthier, E., Bannwart, J., Paul, F., and Zemp, M. 2025: Annual mass change of the world’s glaciers from 1976 to 2024 by temporal downscaling of satellite data with in-situ observations. Earth System Science Data 17(5): 1977-2006, https://essd.copernicus.org/articles/17/1977/2025/.

Raup, B., Andreassen, L., Boyer, D., Howe, C., Pelto, M., and Rabatel, A. 2025: Tracking extinct glaciers in GLIMS. Annals of Glaciology, 66, e35, 1–6. https://doi.org/10.1017/aog.2025.10027

The GlaMBIE Team, 2025: Community estimate of global glacier mass changes from 2000 to 2023. Nature. https://doi.org/10.1038/s41586-024-08545-z.

WGMS 2023: Global Glacier Change Bulletin No. 5 (2020–2021). Zemp, M., Gärtner-Roer, I., Nussbaumer, S.U., Welty, E.Z., Dussaillant, I., and Bannwart, J. (eds.), ISC(WDS)/IUGG(IACS)/UNEP/UNESCO/WMO, World Glacier Monitoring Service, Zurich, Switzerland, 134 pp., publication based on database version: doi:10.5904/wgms-fog-2023-09. [NG5] [MP6] 

Datasets used and their URLs

Dussaillant, I., Hugonnet, R., Huss, M., Berthier, E., Bannwart, J., Paul, F., and Zemp, M. (2025): Annual mass-change estimates for the world’s glaciers. Individual glacier time series and gridded data products. Digital media. https://doi.org/10.5904/wgms-amce-2025-02b[NG7] [MP8] 

43rd Field Season of North Cascade Glacier Climate Project

On By mspeltoIn glacier climate change, glaciers salmon, Heat waves glacier melt, North Cascade GlaciersLeave a comment
Lower Curtis Glacier terminus in 2025 with overall results of our work 1984-2025.

2026 Field Season: For the 43rd consecutive summer we are heading into the field to measure and communicate the impact of climate change on North Cascade glaciers. This field season follows the 2021-2025 seasons that featured either historic heat waves and/or periods of extended warm weather. The heat led to a greater exposure of bare ice on glaciers with a higher albedo and greater density. The observed melt rates are 7-9 cm/day water equivalent during warm weather events vs 4-6 cm/day for snow surfaces. This led to substantial mass losses on North Cascade glacier for the five years of ~8m. This winter was poor and the summer will be hard on glaciers. This year we have provided support from Alpine Start, Marmot, Protect our Winters and Smartwool.

Science objectives: We will complete detailed measurements on 10 glaciers, three of which are part of the World Glacier Monitoring Service reference glacier network (48 glaciers globally), which have 30+ consecutive years of mass balance observations. This summer we will have an opportunity to assess the long-term ramifications of the 2021-2025 period of unprecedented mass balance losses and associated glacier changes, with detailed mass balance, crevasse depths and glacier surface elevation profiling.  We also focus on the impact of diminishing glacier size on downstream runoff.

Art Objectives: We will collaborate with several artists who will join us for a portion of the field season. They will be able to create their own work about the landscape and the science or may join us for fieldwork and make plans for future artwork. We hope to use this art to share our research with a broader audience and highlight the beauty and importance of these places. 

Communication Objectives: We will leverage the brands of our expedition sponsors and local organizations that we are building collaborations to focus on continued rapid glacier loss and the downstream effects.  We will utilize a combination of artists and scientists to tell the story.

Painting by Jill Pelto of the Nooksack watershed illustrating connections from glacier to the sea.

Bios

Jill Pelto (she/her) is an artist and scientist from New England who grew up loving winter sports and trips to the mountains. She incorporates scientific research and data into paintings and prints to communicate environmental changes. 2025 was Jill’s 17th field season. She has coordinated an art gallery exhibit “Shaped by Ice” in Seattle in 2025 and in Winthrop, WA in 2026. She is excited about continuing to document the change in North Cascade glaciers that she has witnessed each of the last ten years —through science and art.

Mauri Pelto (he/him) has directed the project since its founding in 1984, spending more than 800 nights camped out adjacent to these glaciers. He is the United States representative to the World Glacier Monitoring Service. For 16years he has been author of the blog “From a Glacier’s Perspective”, and associate editor for three science journals.  He is on the Science Advisory Board for NASA’s Earth Observatory. His primary position is Associate Provost at Nichols College, where he has been a professor since 1989. He either runs on trails or skis on alpine and cross country trails every day.

Ava Reynolds is a printmaker examining the relationship between environmental beauty and climate change in her work. Ava holds a B.A. in Global Sustainability and a B.A. in Studio Art from the University of Virginia (2020), and is in her first year at the Rhode Island School of Design, pursuing an MFA in Printmaking. She finds inspiration for her prints from organic forms, natural landscapes, and climate change data and seeks to use art as a medium to engage with a large audience about the impacts of climate change.

Shaina Dotson is a Seattle-based creative with a BFA in Metalsmithing whose hobbies include metal arts, fiber arts, and printmaking. She serves on the board of the Washington Alpine Club and instructs for their Basic Climbing Class, sharing her love of the mountains with new climbers. Shaina is an avid mountaineer who finds joy in exploring the forests, peaks, and wild places of Washington State. Her deep connection to the landscape, combined with a love of learning and giving back to her community, naturally drew her to this project. She looks forward to creating new work inspired by the glaciers of Washington and the research this project brings to light.

Rikki Held is an early-career scientist passionate about understanding Earth and climate systems and communicating science through film. Growing up on her family’s ranch in southeastern Montana and studying the adjacent river with USGS scientists sparked her interest in investigating the complex Earth systems in which we live. She earned her B.A. in Environmental Science at Colorado College and has conducted interdisciplinary research, taught high school biology and chemistry through the Peace Corps in Kenya, and communicated climate impacts through her climate advocacy work in Montana. In graduate school, Rikki aims to study glaciology and climate variability to better predict future change. She looks forward to learning from the scientists and artists involved in NCGCP and creating a short documentary on their inspiring work. 

Abby Conner (she/her) is a water resources professional with a passion for connecting people to their local watersheds. She earned her M.S. in Civil Engineering from the University of Colorado and returned to the PNW, where she serves on the board of the Carkeek Watershed Community Action Project and volunteers with the Mountaineers. She looks forward to bringing her background in water resources to the NCGP and exploring the connections between North Cascade glaciers and the communities downstream.

Nina Adjanin (she/her) is an associate professor at Northwest Missouri State University. Her work integrates technology and immersive experiences to explore the intersection of education, extreme environments, and the impact of climate change on high mountains and polar regions. Beyond her academic work, Nina is an experienced high-altitude mountain guide and adventurer, with expeditions that have taken her to extreme environments around the world and shaped her interdisciplinary approach to research. Nina is thrilled to be joining this project documenting the changes in the North Cascade glaciers, bringing her background in extreme environments and climate change research. 

Danielle Schlunegger-Warner is a multi-disciplinary artist working in sculpture, installation, and experimental digital photography, to celebrate the wonder of the natural world. After graduating from California College of Art with a BFA in Sculpture, she has fabricated and designed museum exhibits for over ten years and maintained an independent art practice including science communication projects. For NCGCP, Danielle plans to continue combining her art, science, and museum exhibit background. She will investigate how the rapidly changing glacial landscape of the Cascades can be seen through the lens of a microscope, intertwining field microscopy, image projection, and artistic observations illustrating impact of smallest forms of life the greater environment.

Team on Rainbow Glacier in 2025 from left Katie Hovind, Caitlin Quirk, Claire Sianna Seaman, Jill Pelto and Margaret Kingston.

2026 Schedule 

  • July 28:   Hike In Lower Curtis Glacier
  • July 29:   Lower Curtis Glacier survey
  • July 30:   Hike Out Lower Curtis/Hike in Ptarmigan Ridge
  • July 31:   Sholes Glacier
  • Aug. 1:    Rainbow Glacier
  • Aug. 2:    Rainbow Glacier
  • Aug. 3:    Hike out. Hike in Easton Glacier (Resupply in Bellingham WA) 
  • Aug. 4:    Easton Glacier
  • Aug. 5:    Easton Glacier
  • Aug. 6:    Squak Glacier
  • Aug. 7:    Talum Glacier
  • Aug. 8:    Hike out Hike in Columbia Glacier (resupply in Monroe WA)
  • Aug. 9:    Columbia Glacier
  • Aug. 10:  Hike out Columbia-Hike in Daniels
  • Aug. 11:  Mount Daniels Survey
  • Aug. 12:  Ice Worm-Hike out

Barnes Ice Cap and Baffin Island Glaciers Lose Snow Cover in July 2026

On By mspeltoIn Canada glacier retreat, climate change glacier retreatLeave a comment
Barnes Ice Cap having in Landsat image with well developed melt channels from crest to margin of ice cap. Snow cover has been lost with over a month left in melt season.

Barnes Ice Cap located in the center of Baffin Island, Canada covers an area of ~5731 km2 in 2021 (Rippin et al 2026). The ice cap is approximately 150 km long, 60 km wide and has maximum ice thickness of ~730 m and a maximum ice elevation of 1124 m above sea level (asl) at the summit of the north dome. ICESat altimeter data indicated the thinning of the BIC at a mean rate of 0.75 m/year for the 2003–2009 period Gilbert et al (2016). They also noted that the ELA was at 950 in the 1960-80 period and is at 1100 m from 2002-2010 this leaves  a limited accumulation zone area. observe that  Barnes  Ice Cap lost its accumulation area beginning in 2010, in part due to the longer melt season.  The glacier does tend to not retain snowcover the accumulation zone consists of superimposed ice at the crest. Papasodoro et al (2016) noted that glacier wide balances were −0.52  m w.e./year from 1960 to 2013 and doubled to −1.06m w.e./year from 2005 to 2013 and remained at ~-1 m/a year through 2021 (Rippin et al 2026).

This has enabled supraglacial channels/valleys to develop and expand from year to year, extending from the ice cap crest to the margin, providing an effective pathway for meltwater to leave the ice sheet (Rippin et al 2026). This greatly diminishes refreezing, which had been the key mechanism for accumulation. The channels persist through and between melt seasons. There is insufficient ice motion or annual accumulation to offset the melt season runoff impact. Note the Band 4 image below indicates the extent of specific channels and how they cross cut specific stratigraphic ice horizons (H). Winter conditions were 3-5 C above average in the area, with spring and early summer conditions being normal or slightly below normal. This combined with the rapid snow loss on the ice cap between June 24 and July 12 indicates that snowpack was thin.

Barnes Ice Cap southern lobe with specific supraglacial stream channels noted. These have incised into the surface and persist. They cross stratigraphic ice horizons (H) near the margin of this Landsat Band 4 image from July 12, 2026.
Winter temperature anomaly across the Arctic.
Glaciers on Peninsula on northern side of Home Bay having lost nearly all snowcover by July 15, 2026 in this Landsat image.

In mid-July 2026 Landsat imagery indicates the loss of all snow cover on Barnes Ice cap and that the supraglacial streams are fully activated. A series of glaciers to the east of the ice cap also have lost all snowcover including Keyhole, Kitarchick and Nuusuq Glacier. With over a month left in the melt season this will lead to substantial mass balance loss of these glaciers, driving further thinning and recession. Decade Icefield just to the north of this trio of glaciers also has lost all snow cover by mid-July.

Decade Icefield in Landsat image from mid-July has lost its snow cover.
Barnes Ice Cap southeast region illustrating suprglacial stream extent and lack of snowcver from margin to summit of ice cap in Landsat image.

Miles Glacier, Alaska Retreat-Van Cleve Lake Outburst 2026

On By mspeltoIn alaska glacier retreat, climate change glacier retreat, glacier climate change2 Comments
Miles Glacier and Van Cleve glacier lake (VC) near its maximum size on June 19th and after drainage on July 9th in Sentinel images. Glacier margin black dots.

Miles Glacier terminates in an embayment on the east side of the Copper River, Alaska. A secondary terminus on the north side of the main glacier has long impounded a glacial lake that periodically drains. As miles has retreated over the last 40 years the maximum size of the glacial dammed lake has diminished, prior to its drainage. In 1987 the glacier extended onto an outwash plain directly adjacent to the Copper River, the lake reached a maximum size of 12 km2 . From 2016 to 2019 the lake drained each summer reaching a maximum average size of 5.5 km2 (Rick et al 2023). This was noted as a shrinking ice dammed lake by Field et al (2021).

Miles Glacier and Van Cleve glacial lake filling in June 2026 in Landsat images. Glacier margin black dots.

By 2021 the glacier had retreated 3.5 km since 1987. From 2021-2026 the lake reaches a maximum size of 3.5 to 4.0 km2 before draining. On June 2, 2026 the lake still has some winter lake ice and is filling. By June 10th the lake had reached 3 km2 and by June 19th it had reached 4 km2. The lake had began draining before June 25th. By July 9th it was fully drained. The Miles Glacier terminus has retreated 4.5 km since 1987. This ongoing retreat will continue to diminish the size of the lake. Ths lake does not have the complex drainage system or changing drainage location that Berg Lake has with retreat of Stellar Glacier..

Miles Glacier and Van Cleve glacial lake in 1987 Landsat image. Black dots indicate glacier margin.

Miles Glacier and Van Cleve glacial lake in 2021 Landsat image. Black dots indicate glacier margin and yellow arrow indicates 1987 margin.

Hovgard Kystland Glacier Rapid Retreat, West Greenland

On By mspeltoIn climate change glacier retreat, glacier climate change, Glacier Observations, Greenland glacier retreatLeave a comment
Hovgard Kystland Glacier in Sentinel image from July 4, 2026 with margin indicated by black dots. The 2020 margin seen below is indicated by green dots.

Hovgard Kystland Glacier is an outlet glacier in West Greenland between Alison and Hayes Glacier. Alison Glacier had the highest retreat rate from 1976-2021 losing 14.3 km in length and 59.4 km2 in terminus area (Black and Joughin, 2026). Hayes Glacier lost 2.7 km in length and 10.8 km2 in area (Black and Joughin, 2026).. They indicate that Hovgard Kystland Glacier retreated 5.4 km and lost 21.3 km2 during this interval.

Here we examine the acceleration of retreat from 2020 to 2026. In 2020 the central tongue of the glacier extended west beyond the main front. This central tongue collapsed by July 2024 leaving a generally north/south calving front, the glacier had lost 5.7 km2 of terminus area. From July 2024 to July 2026 an embayment formed generating a concave calving front. The glacier terminus lost another 4.8 km of area. Retreat of the calving front was 2.5 km during the 2021-2026 period. The glacier has lost an area that is 50% of the area lost from 1976-2021, in the last five years. The embayment is poised to further expand, though this summer an extensive packed melange is currently in place which typically limits calving (Meng et al. 2025).

Hovgard Kystland Glacier in Sentinel image from July 27, 2020. The 2020 margin seen below is indicated by green dots and the 2026 margin with black dots.

Hovgard Kystland Glacier in July 4, 2024 Sentinel image. The calving front indicated by red dots for 2024 and black dots for 2026.

Alpine Glaciers-State of Climate 2024

On By mspeltoIn climate change glacier retreat, glacier climate changeLeave a comment
Global alpine mass balance in 2024 as reported to the World Glacier Monitoring Service. Solid line is the cumulative balance, bars are the annual balance.

Each of the last 15 years I have summarized the annual mass balance of alpine glaciers globally for the Bulletin American Meterological Society-State of the Climate report,. Below is the 2024 section on alpine glaciers with a few added figures.

  • ALPINE GLACIERS
  • M. Pelto

In 2024, all 58 global reference glaciers reported a negative annual mass balance. This is only the second year in the 1970–2024 period with all negative annual balances, following 2023. The global average annual mass balance based on equal weighting of 19 regions is −1.30 m water equivalent (w.e.), the most negative value in the record

The 2024 dataset of submitted glaciological observations includes 142 glaciers from six continents and 27 nations, with 140 reporting a negative balance and 2 a positive balance. In 2024, the mean annual mass balance of the 58 global reference glaciers was −1.44 m w.e. and −1.36 m w.e. for all 142 reporting glaciers. This is a similar result to 2023, which saw a mean reference glacier balance of −1.62 m w.e. and −1.35 m w.e. for all 116 reporting glaciers.

The 2024 regionalized global average of −1.30 m w.e. exceeds the previous most negative year in 2023, which saw a regional-ized global average of −1.25 m w.e. This makes 2024 the 37th consecutive year with a global alpine mass balance loss and the 15th con-secutive year with a regionalized global mass balance below −0.5 m w.e. The acceleration of mass balance loss indicates that alpine glaciers are not approaching equilibrium. The acceleration of mass balance loss is apparent regardless of datasets used to determine it, including glaciological, geodetic, altimetry, and gravimetric observations (The GlaMBIE Team 2025). The intercomparison assessment identified that global glaciers annually lost 273+26 gigatons (Gt) in mass from 2000 to 2023, with loss having been 36% greater in the second half than in the first half of this period (The GlaMBIE Team 2025).

In the European Alps, all 49 glaciers reported negative mass balances, with 45 losing over 1 m w.e. All 10 Icelandic glaciers had negative balances. In Svalbard, all seven had negative balances exceeding an exceptional loss of 1.25 m w.e. This was the result of near complete snow cover loss across most glaciers (Fig. 2.20) following record temperatures in August (see section 7f5 for details). Twelve of the 13 glaciers from Norway and Sweden had mass losses of more than 1.0 m w.e.

High snow line persisted through the winter on Mount Everest glaciers.

Across High Mountain Asia, 20 of 21 glaciers, reporting from seven nations, had negative balances. The highest average losses were in the Himalayas of Nepal and the lowest in the Pamir Range of Tajikistan.

In the Andes Mountains of South America, all 14 glaciers, reporting from five nations, had negative balances. Conejeras Glacier (Colombia), following a 5.04 m w.e. loss in 2023, was declared extinct in 2024. The daily hydrograph below this glacier changed from a predominanceof days with a purely melt-driven hydrograph from 2006 to 2016 to an increase in the frequency of days with flows less influenced by melt after 2016 (Morán-Tejeda et al. 2018).

All 16 glaciers in North America had negative balances. All four glaciers in Arctic Canada had mass balance losses under 1 m w.e. In western Canada and Washington and Montana (United States), all 16 glaciers reporting had losses exceeding 1 m w.e. The Ice Worm Glacier (Washington) was listed as extinct in 2023 after 40 years of continuous observations (Pelto 2024). In 2024, loss from the relict ice (ice that is no longer moving or part of a glacier) was 2.4 m and melt runoff below the glacier had decreased similar to Conejeras Glacier (Pelto and Pelto 2025). In Alaska, all three glaciers had mass balance losses. Davies et al. (2024) examined the Juneau Icefield, the most observed icefield in Alaska in terms of mass balance, and found an acceleration of mass loss with a doubling after 2010 compared to 1979–2010.

Easton Glacier, Washington extensive retreat since 1990, with last five years being the most rapid. Terminus and mass balance surveyed annually and reported to WGMS.

Alpine annual mass balance glaciological observations are reported to the World Glacier Monitoring Service (WGMS) by national representatives with a 1 December annual submission deadline. WGMS reference glaciers have at least 30 continuous years of mass balance observa-tion. Benchmark glaciers have at least a 10-year mass balance record and are in regions that lack sufficient reference glaciers. The combination of benchmark and reference glaciers is used to generate regional averages (WGMS 2023). Global values are calculated using a single averaged value for each of 19 mountain regions, limiting bias from observed regions (WGMS 2023). As this dataset expands, the annual values are reanalyzed and updated.

The lack of snow pack at the end of summer is evident across Edgeoya in Svalbard, blow a closeup of Digerfonna further illustrates with lettered points indicating new bedrock areas that are expanding amidst the ice cap.

Grosser Aletsch Glacier Rapid Snow Loss June 2026

On By mspeltoIn climate change glacier retreat, switzerland glacier retreatLeave a comment
Snow line in Sentinel images from June 2026 at 2450 m on June 11 and at 2850 m on June 27th.

In June of 2025 heat waves combined with limited winter snowpack set the stage for significant glacier loss, 3% of the volume of Swiss Glacier. This followed on the exceptional losses in 2022 and 2023.

This same story in playing out through June of 2026, which will lead to this being the fourth year in the last five with exceptional glacier mass balance loss. On Grosser Aletsch Glacier on June 11th the snow line on the glacier was at 2450 m. By June 24th it had risen to 2800 m and by June 25th/27th 2850-2900 m. This is similar to the rapid rise of 400 m observed on Argentiere Glacier, France.

Grosser Aletsch Glacier snow line on June 25, 2026 averages 2850 m in this Landsat image.

The snow line rose to a record high 3200 m in 2022, and reached in 3100 m in 2025. Will 2026 set a new record? The snow line is not as high as the same date in 2022, though within ~25 m, but higher than late June 2025.

Above the late June snow line on Grosser Aletsch Glacier in 2022 and 2025 in Sentinel images. These two years had extensive June heat waves after winters with low snowpack. At the end of summer the snow line had risen to 3200 m in 2022 and 3100 m in 2025.

Argentiere Glacier, France Rapid Snow Line Rise June 2026

On By mspeltoIn france glacier retreat, Heat waves glacier melt1 Comment
On June 1, 2026 the snowline is near the terminus of Argentiere Glacier at 2300 m, by June 24, 2026 the snowline has rise upglacier 3.3 km to 2700 m.

The French Alps have expereienced a significant June heat wave that has driven a rapid rise in glacier snow lines. Rabatel et al (2013)  examined the equilibrium line altitude (ELA) of glaciers in the region from 1984-2010.  The ELA is the snowline at the end of the summer melt season.   Rabatel et al (2013) found the average snow line of 3000 m on Trient Glacier, 2900 m on Tour Glacier, and 2800 m on Argentiere Glacier.  

On June 1st and 7th 2026 the snow line on Argentiere Glacier was near the terminus at 2300 m, by June 24th the snow line risen to 2700 m. This is 100 m shy of the average end of summer snow line, with 25% of the glacier losing its snowcover in this period. In 2015 and 2017 the snowline reached a record height of 2950 m in late August. This snow line rose to 3000 m again in August of 2022 and to 2900 m in August 2023. The snow lines from these years are in images below

The high snow lines result in a limited accumulation zone and an expanded ablation area leading to mass balance losses and terminus retreat. Argentiere Glacier is a World Glacier Monitoring Service reference glacier, with the data indicated in the images below. The glacier advanced from the early 1960s to early 1990s and since driven by negative mass balances in all but one year this century has retreated ~ 1 km. The mass balance loss has exceeded 1 m in most years this century and will again this year.

Annual mass balance reported to WGMS for Argentiere Glacier.
Terminus change reported to WGMS for Argentiere Glacier.
Argentiere Glacier snow line at end of 2015 melt season at 2950 m in Landsat image.
Argentiere Glacier snow line at end of 2017 melt season at 2950 m in Landsat image.
Argentiere Glacier snow line at end of 2022 melt season at 3000 m in Sentinel image.
Argentiere Glacier snow line at end of 2023 melt season at 2900 m in Sentinel image.

Bear Glacier, Alaska October 2025 Lake Outburst

On By mspeltoIn alaska glacier retreat
Bear Glacier ice dammed lake filled on Oct. 10th and drained on Oct. 17th, 2025. The Sentinel images also illustrated rifts.

Bear Glacier, Alaska on the Kenai Peninsual due to retreat developed an ice dammed proglacial that periodically drains. An August drainage in 2014 and 2018 were noted by Kurtz and Wolken (2019). Recent increases in kayaking and standup paddle boarding has led to this lakes drainage posing a recreational hazard. In 2024 the lake drained between 8/14 and 9/7. It then had filled by July and remained filled into October. On October 10th the lake had an area of 0.85 km2. On October 17th, the lake had drained to an area less than 0.18 km2. Their are a series of rifts extending across the glacier that represents flexure of the ice due to water level/flotation changes of this ice tongue. The ice is lifted when the lake is full and then is let down during drainage.

Bear Glacier ice dammed lake filled on Aug. 14th and drained on Sept. 7th, 2024 The Sentinel images indiate glacier rifts.

On June 4, 2026 the lake has begun to refill with an area of 0.55 km2 It is evident that this lake that had emptied periodically now empties annually. The date of drainage has been later in the melt season in 2024 and 2025. The continued retreat of the glacier that averaged 160 m/year from 2005-2019 (NPS, 2019), will lead to continued changes in drainage of this lake. The thinner ice is more easily lifted via flotation allowing for drainage with a more limited lake volume. The rapid lake development is a frequent pattern in the region we have observed at Excelsior Glacier Pederson Glacier and Ellsworth Glacier.

Bear Glacier ice dammed lake filled on Oct. 10th and drained on Oct. 17th, 2025. The Sentinel images indiate glacier rifts. Note increased icebergs after drainage.

Bear Glacier dammed lake filling in June of 2025 and 2026 with an area of 0.5-0.6 km2.

North Cascade Glacier Accumulation Season 2025/26

On By mspeltoIn Glacier Observations, North Cascade Glaciers
View from Heather Meadows to Table Mt on May 2, 2026 (Jill Pelto photo)

Since 1984 we have measured glacier mass balance on North Cascade glaciers every year. Mass balance is the difference between accumulation (income) and melt (expenses). The accumulation season typicallys ends around May 1. In 2026 it ended on April 19.

In early December snowpack was average above 1500 m (5000 feet) and limited below. The region was then impacted by a historic atmospheric river from Dec. 8-12. that led to flooding and landslides closing I-90 and Highway 2. Snowpack was completely lost at most locations below 1500 m including the Mount Baker station in Heather Meadows (1285 m). Above 1500 m at Lyman Lake (1825 m) SWE increased by 15 cm, which was 50% of the 30 cm of precipitation that fell in this period. The last half of December snow depth increased from 0 to 1.5 m at Heather Meadows. Snowpack built to 1.2 m w.e. at Lyman Lake by March 15, and then hovered around this peak until mid-April. At Heather Meadows snowpack depth peaked at 2.8 m on March 15th and was at 2.7 m on April 15th. This April 15th represented the maximum snowpack for elevations at 1500 m and above. The snowpack was less than 50% of normal below 1800 m. Above 2000 m warm wet winter events did deliver snowfall that was rain below and the situation is likely better. Working with Snowgoat Skimo as they prepare for the Kulshan Randoneee has noted snowpack of over 6 m at the 2000 m level.

The transition to melt season was rapid with a particularly warm period from April 26-May 4 has led to rapid melt off of snowpack. At Lyman Lake a third of the snowpack was lost by May 8th. At Heather Meadow 50% of snowpack depth was lost by May 8th.

Mount Baker snow depth station indicating loss of snow in December atmospheric river, then rapid development and finally the unusually rapid drop in late April. WSCO graph.


View toward lower Heather Meadows and Baker ski area-snowline above 1200 m on 5-2-26.-where the snowpack is already thin. (Jill Pelto photo)

Sentinel Image from 5-7-2020 a normal snow year-snow line 850 m.

Sentinel image from 5-4-2026 illustrating regional snow line at 1200 m. The limited winter snowpack indicates that in 2026 we have a low accumulation/income for glaciers and melt/expenses already underway. Coleman Glacier terminus (E) is already exposed ice the first week in May. We will be in the field this summer to measure the details. We are expecting more bare ice and rockfall during our work.

Sentinel image from 5-6-2025 snow cover- snow line 975 m.

Sentinel image from 5-9-2024 with snow line at 975 m.

Looking from Austin Pass across to Shuskan on 5-3-26 (Jill Pelto photo)

The outlook is poor for glaciers and snowpack in the Pacific Northwest in 2026. How this measures up with the snow drought of 2015 that we reported on in a project with NASA will be important to observe.

Occidental Glacier, Chile Terminus Tongue Poised to Collapse

On By mspeltoIn chile glacier melt, chile glacier retreat
Occidental Glacier in Sentinel images from Dec. 2024 and March 2026 indicating the rapid narrowing of the terminus tongue A, that from the numerous icebergs is actively underway.

Occidental Glacier is an outlet glacier draining west from the Southern Patagonia Icefield. In 2015 the glacier terminus rested on the western shore of a proglacial lake where it bends to the northwest. At Point B a glacier lake was dammed by the ice front. From 2015 to 2021 the northwestern margin of the terminus retreated along the northern shore of the lake. By 2021 the lake at Point B was no longer ice dammed and its water level had declined. The terminus tongue (A) continued to extend to the western shore providing a stable pinning point through 2025.

In 2026 the connection to the western shore has narrowed with the embayment at Point B extending north and east. The terminus tongue (A) on March 22, 2026 is just 850 m wide and actively narrowing, note fresh icebergs. This connection is not stable and will not endure, which will generate significant terminus retreat. This glacier follows neighbors to the north Tempanos and Bernardo Glacier in this process each retreat leading to lake expansion, but also drainage of ice dammed lakes.

Occidental Glacier in Landsat images indicating the retreat of the terminus along the northern shore, the drainage of the embayment at B indicating diminished connection to the western shore of the lake.
In 2020 Bernardo, Tempanos and Occidental Glacier had wide terminus tongues terminating in proglacial lakes.
By 2026 Bernardo, Tempanos and Occidental Glacier terminus tongues had retreated and narrowed leading to both expansion of proglacial lakes and drainage of a couple ice dammed lakes that the terminus had impounded.

North Cascade Glacier Climate Project Year of Glacier Preservation Observations

On By mspeltoIn glacier climate change, Glacier Observations, glaciers salmon, North Cascade Glaciers

March 21, 2026 was World Day for Glaciers, telling this story is an ongoing four decades long project for us. The North Cascade Glacier Climate Project began in 1984 to identify the response of Washington’s North Cascade glaciers to climate change. The 2026 field season will mark our 43rd year of observations.

I  co-direct the project as the science director, with Jill Pelto as the art director. We strive to create a diverse and collaborative portfolio of impactful observations connecting people to science through art and data publication. Our theory of change is that art has the power to inspire people by including the emotional context behind the science research. We seek collaborators who are passionate about contributing to and sharing this work. Here we reflect on some of the stories we have shared in the last 12 months that chronicle the rapidly melting reality of glaciers.

In April, 2025 the “Shaped by Ice” exhibit coordinated by Jill Pelto opened at the Slip Gallery in Seattle. This featured work from nine artists, eight of whom had been in the field with us and was the focus of a Seattle Magazine article.

In May we worked with Protect Our Winters to explore what the loss of glaciers, “Beyond the Ice” means for specific regions.

In June, High Country News focused on the use of art to preserve the legacy of glaciers, given the glaciers themselves are not being preserved.

In March through July we worked with the Global Glacier Casualty List to the tell the story of specific glaciers in the United States that are disappearing, including Ice Worm Glacier in the North Cascades, Darwin Glacier in the Sierra Nevada, Twins Glacier in Wyoming and Burroughs Glacier in Alaska.

In August our field season coincided with a Seattle Time report, on Melting Mountains in the Pacific Northwest means, that we collaborated on.

Joining us in the field on the Lower Curtis Glacier, Mount Shuksan was KING5 NBC-Seattle affiliate, led by Meteorologist Leah Pezzetti who backpacked with us into her first glacier. The logistical preparation for this by KING5 was thorough, and we provided guidance and support to them. The resulting feature was released while we were still in the field.

Upon returning to the trailhead from Lower Curtis Glacier a CBS Sunday Morning News team met us and travelled into the field with us to Sholes Glacier, Mount Baker. The overnight trip into the backcountry was a first for this news team and required extensive collaborative support. The results were shared just two weeks after the filming, and right after our field season.

We worked for a second year with Dan MacComb on a short film for the UN International Year of Glaciers’ Preservation called “Shaped by Ice”. This film published by Protect our Winters has been featured in tfour film festivals during 2025.

In January through February a second “Shaped by Ice” gallery event was held in at the Confluence Gallery in Twisp WA. This was spearheaded by Jill Pelto, Margaret Kingston, and Claire Waichler.

A poor winter snowpack will certainly lead to another year of extensive glacier loss across the Pacific Northwest and we will be there to observe it.