Ablation stakes on Gulkana Glacier, Alaska. Late summer fieldwork on Gulkana Glacier reveals ablation stakes emerging from the ice. Measurements of the change in the height of the snow and ice at these stakes is one aspect of determining glacier mass balance.
2025 USGS Benchmark Glaciers Executive Summary
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By Ecosystems Land Change Science Program
March 11, 2026
2025 Data Now Available: Explore how the USGS Benchmark Glaciers have changed in 2025
Return to Glaciers and Landscape Change
Explore the USGS Benchmark Glaciers mass balance methods for measuring glacier change
2025 Benchmark Glacier Results
Benchmark Glaciers in Alaska had variable (and modest) mass gains and losses (Fig. 1).
- Wolverine Glacier gained mass in 2025, the first time since 2012.
- Gulkana and Lemon Creek Glaciers lost mass for the 17th and 13th consecutive years, respectively.
Benchmark Glaciers in the contiguous states had record and near record mass losses
- Glacier mass loss at South Cascade Glacier (Washington) was the highest on record.
- Mass loss at Sperry Glacier (Montana) was the second highest on record.
Overall, 2025 was characterized by glacier mass loss driven primarily by warm summer conditions, with Wolverine Glacier as a notable exception.
Media
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Media
Sources/Usage: Public Domain. View Media Details
How did 2025 annual mass balances compare to previous years?
In Alaska, Gulkana and Lemon Creek glaciers experienced moderate mass loss, marking their 17th and 13th consecutive years of negative annual mass balance, respectively. Conversely, Wolverine Glacier experienced moderate mass gain — its first positive annual mass balance since 2012, ending a 12-year streak of negative balances. In the contiguous United States, Sperry Glacier in Glacier National Park, MT saw its second highest mass loss year since measurements began in 2005. South Cascade Glacier in the Cascade Mountains of Washington underwent the greatest mass loss year since measurements began in 1958 (Fig. 2.).
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How did winter snowfall contribute to each glacier's mass balance?
At Wolverine Glacier, winter precipitation exceeded normal levels beginning in November and remained above average throughout the remainder of the 2024 – 25 accumulation season. Lemon Creek Glacier experienced near-normal winter precipitation through the accumulation season. At Sperry Glacier, precipitation began accumulating approximately one month later than normal. Gulkana, Sperry, and South Cascade glaciers all ended the 2024 – 25 accumulation season with below-average winter precipitation (Fig. 3.).
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How did summer temperatures contribute to each glacier's mass balance?
All three Alaska glaciers experienced cooler than average temperatures during the first half of summer, limiting melt. Wolverine and Gulkana Glaciers had a delayed start to the ablation season. At Wolverine Glacier remained cooler than average through the end of summer, contributing to its positive mass balance. Gulkana and Lemon Creek glaciers ended the summer moderately warmer than average, offsetting some of the effects of the cool early season. In the contiguous United States, both Sperry and South Cascade glaciers experienced significantly warmer than average temperatures throughout the summer, driving the exceptional mass loss observed at both sites (Fig. 4.).
Explore the USGS Benchmark Glaciers in context of global glacier studies
Glaciers and Landscape Change
Mountain glaciers are dynamic reservoirs of frozen water, deeply interconnected with their surrounding ecosystems. Glacier change in North America has major societal impacts, including to water resources, natural hazard risk, tourism disruption, fisheries, and global sea level change. Understanding and quantifying precise connections between changing glaciers, the surrounding landscape and climate...
Aerial photographs of South Cascade Glacier represent 57 years of change
Aerial photograph of South Cascade Glacier, WA taken August 13th, 1958 (before image) and October 14th, 2015 (after image).
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Ablation stakes on Gulkana Glacier
Ablation stakes on Gulkana Glacier, Alaska. Late summer fieldwork on Gulkana Glacier reveals ablation stakes emerging from the ice. Measurements of the change in the height of the snow and ice at these stakes is one aspect of determining glacier mass balance.
Collecting Field Data at Gulkana Glacier
USGS scientists collect field data at Gulkana Glacier in the eastern Alaska Range. The checkerboard sampling pattern in the foreground indicates where snow pit density measurements were collected.
USGS scientists collect field data at Gulkana Glacier in the eastern Alaska Range. The checkerboard sampling pattern in the foreground indicates where snow pit density measurements were collected.
Gulkana Glacier weather station
A scientist checks data collection on multiple sensors at the Gulkana Glacier weather station where snow blankets the glacier surface.
A scientist checks data collection on multiple sensors at the Gulkana Glacier weather station where snow blankets the glacier surface.
View South from Wolverine Glacier
View South from Wolverine Glacier
Ablation Stake on Wolverine Glacier
An ablation stake which began the summer below the surface of the snow is shown here in the fall, extending far above bare ice surface of Wolverine Glacier, Alaska. A USGS scientist carries a portable steam drill, used to install the stakes in the glacier.
An ablation stake which began the summer below the surface of the snow is shown here in the fall, extending far above bare ice surface of Wolverine Glacier, Alaska. A USGS scientist carries a portable steam drill, used to install the stakes in the glacier.
Hydrologic Technician measuring discharge. South Cascade Glacier, WA.
Hydrologic Technician measuring discharge. South Cascade Glacier, WA.Hydrologic Technician Dan Restivo of the USGS Washington Water Science Center admires the view while measuring discharge at the base of the South Cascade Glacier station 12181090 South Cascade Middle Tarn near Marblemount, WA.
Hydrologic Technician measuring discharge. South Cascade Glacier, WA.
Hydrologic Technician measuring discharge. South Cascade Glacier, WA.Hydrologic Technician Dan Restivo of the USGS Washington Water Science Center admires the view while measuring discharge at the base of the South Cascade Glacier station 12181090 South Cascade Middle Tarn near Marblemount, WA.
Taku Glacier, Alaska retreat
2019 Juneau Icefield Research Program (JIRP) students during a four day and 83 kilometers ski traverse across Taku Glacier, carrying all their food, water, clothing, tents, and science gear as they help measure the mass balance along the way.
2019 Juneau Icefield Research Program (JIRP) students during a four day and 83 kilometers ski traverse across Taku Glacier, carrying all their food, water, clothing, tents, and science gear as they help measure the mass balance along the way.
Glacier mass balance measurements on Taku Glacier, Alaska
Glacier mass balance measurements on Taku Glacier, AlaskaStudents Stacey Edmonsond (left) and Audrey Erickson (right) of the Juneau Icefield Research Program, measuring glacier mass balance at the flow divide of Taku and Mendenhall glaciers during the summer of 2019
Glacier mass balance measurements on Taku Glacier, Alaska
Glacier mass balance measurements on Taku Glacier, AlaskaStudents Stacey Edmonsond (left) and Audrey Erickson (right) of the Juneau Icefield Research Program, measuring glacier mass balance at the flow divide of Taku and Mendenhall glaciers during the summer of 2019
Firn core with an ice lens collected on Gulkana Glacier, Alaska.
Firn core with an ice lens collected on Gulkana Glacier, Alaska.Firn core with an ice lens collected on Gulkana Glacier during spring 2019 mass balance field work. Gulkana Glacier is located along the south flank of the eastern Alaska Range.
Firn core with an ice lens collected on Gulkana Glacier, Alaska.
Firn core with an ice lens collected on Gulkana Glacier, Alaska.Firn core with an ice lens collected on Gulkana Glacier during spring 2019 mass balance field work. Gulkana Glacier is located along the south flank of the eastern Alaska Range.
Researcher on Sperry Glacier
Researcher holds an ablation stake and winter snow probe during spring mass balance field work on Gulkana Glacier, AK.
Researcher holds an ablation stake and winter snow probe during spring mass balance field work on Gulkana Glacier, AK.
View of Nellie Juan Glacier from Wolverine Glacier
View of Nellie Juan Glacier from Wolverine GlacierView of Nellie Juan Glacier from Wolverine Glacier
View from Wolverine Glacier from Helicopter
View from Wolverine Glacier from Helicopter
A windblown stand of hemlock trees at the Wolverine Glacier field site
A windblown stand of hemlock trees at the Wolverine Glacier field siteA windblown stand of hemlock trees at the Wolverine Glacier field site
A windblown stand of hemlock trees at the Wolverine Glacier field site
A windblown stand of hemlock trees at the Wolverine Glacier field siteA windblown stand of hemlock trees at the Wolverine Glacier field site
Satellite image of Taku Glacier in October 1, 2018
Satellite image of Taku Glacier in October 1, 2018Satellite image of Taku Glacier in October 1, 2018. The Norris Glacier can be seen on the lower left hand corner and the Hole-in-the-Wall Glacier in the upper center portion of the image. Citation: McNeil, C. J., and Baker, E.
Satellite image of Taku Glacier in October 1, 2018
Satellite image of Taku Glacier in October 1, 2018Satellite image of Taku Glacier in October 1, 2018. The Norris Glacier can be seen on the lower left hand corner and the Hole-in-the-Wall Glacier in the upper center portion of the image. Citation: McNeil, C. J., and Baker, E.
Scientists use ground penetrating radar on Wolverine Glacier, AK
Scientists use ground penetrating radar on Wolverine Glacier, AKResearchers use ground penetrating radar to determine the depth of the snow on Wolverine Glacier. Wolverine Glacier is in the Kenai Mountains on the coast of south-central Alaska. In 1966 scientists with the USGS began making direct measurements of surface mass balance at Wolverine Glacier, one of the "benchmark glaciers" in Alaska.
Scientists use ground penetrating radar on Wolverine Glacier, AK
Scientists use ground penetrating radar on Wolverine Glacier, AKResearchers use ground penetrating radar to determine the depth of the snow on Wolverine Glacier. Wolverine Glacier is in the Kenai Mountains on the coast of south-central Alaska. In 1966 scientists with the USGS began making direct measurements of surface mass balance at Wolverine Glacier, one of the "benchmark glaciers" in Alaska.
Sperry Glacier perimeter: 1966,1998, 2005, 2015.
This image shows the perimeter of Sperry Glacier in Glacier National Park in 1966,1998, 2005, and 2015.
This image shows the perimeter of Sperry Glacier in Glacier National Park in 1966,1998, 2005, and 2015.
Wolverine Glacier
A researcher locates an ablation stake near a crevasse on Wolverine Glacier. These collapsible poles are used to measure snow and ice melt on the glacier surface.
A researcher locates an ablation stake near a crevasse on Wolverine Glacier. These collapsible poles are used to measure snow and ice melt on the glacier surface.
Sperry Glacier snow core
Snow core measurements help scientists determine snow density, which is used to determine the mass balance of Sperry Glacier.
Snow core measurements help scientists determine snow density, which is used to determine the mass balance of Sperry Glacier.
Researchers on Sperry Glacier
Researchers get organized to begin mass balance field work after skiing to Sperry Glacier.
Researchers get organized to begin mass balance field work after skiing to Sperry Glacier.
Researchers at Sperry Glacier
Researchers get organized to begin mass balance field work after skiing to Sperry Glacier.
Researchers get organized to begin mass balance field work after skiing to Sperry Glacier.
Measurement stakes are carried across Sperry Glacier in Glacier NP.
Measurement stakes are carried across Sperry Glacier in Glacier NP.Measurement stakes are carried across Sperry Glacier in Glacier National Park, Montana, during spring mass balance field work in 2019.
Measurement stakes are carried across Sperry Glacier in Glacier NP.
Measurement stakes are carried across Sperry Glacier in Glacier NP.Measurement stakes are carried across Sperry Glacier in Glacier National Park, Montana, during spring mass balance field work in 2019.
2025 Data Now Available: Explore how the USGS Benchmark Glaciers have changed in 2025
Return to Glaciers and Landscape Change
Explore the USGS Benchmark Glaciers mass balance methods for measuring glacier change
2025 Benchmark Glacier Results
Benchmark Glaciers in Alaska had variable (and modest) mass gains and losses (Fig. 1).
- Wolverine Glacier gained mass in 2025, the first time since 2012.
- Gulkana and Lemon Creek Glaciers lost mass for the 17th and 13th consecutive years, respectively.
Benchmark Glaciers in the contiguous states had record and near record mass losses
- Glacier mass loss at South Cascade Glacier (Washington) was the highest on record.
- Mass loss at Sperry Glacier (Montana) was the second highest on record.
Overall, 2025 was characterized by glacier mass loss driven primarily by warm summer conditions, with Wolverine Glacier as a notable exception.
Media
Sources/Usage: Public Domain. View Media Details
Media
Sources/Usage: Public Domain. View Media Details
How did 2025 annual mass balances compare to previous years?
In Alaska, Gulkana and Lemon Creek glaciers experienced moderate mass loss, marking their 17th and 13th consecutive years of negative annual mass balance, respectively. Conversely, Wolverine Glacier experienced moderate mass gain — its first positive annual mass balance since 2012, ending a 12-year streak of negative balances. In the contiguous United States, Sperry Glacier in Glacier National Park, MT saw its second highest mass loss year since measurements began in 2005. South Cascade Glacier in the Cascade Mountains of Washington underwent the greatest mass loss year since measurements began in 1958 (Fig. 2.).
Media
Sources/Usage: Public Domain. View Media Details
How did winter snowfall contribute to each glacier's mass balance?
At Wolverine Glacier, winter precipitation exceeded normal levels beginning in November and remained above average throughout the remainder of the 2024 – 25 accumulation season. Lemon Creek Glacier experienced near-normal winter precipitation through the accumulation season. At Sperry Glacier, precipitation began accumulating approximately one month later than normal. Gulkana, Sperry, and South Cascade glaciers all ended the 2024 – 25 accumulation season with below-average winter precipitation (Fig. 3.).
Media
Sources/Usage: Public Domain. View Media Details
How did summer temperatures contribute to each glacier's mass balance?
All three Alaska glaciers experienced cooler than average temperatures during the first half of summer, limiting melt. Wolverine and Gulkana Glaciers had a delayed start to the ablation season. At Wolverine Glacier remained cooler than average through the end of summer, contributing to its positive mass balance. Gulkana and Lemon Creek glaciers ended the summer moderately warmer than average, offsetting some of the effects of the cool early season. In the contiguous United States, both Sperry and South Cascade glaciers experienced significantly warmer than average temperatures throughout the summer, driving the exceptional mass loss observed at both sites (Fig. 4.).
Explore the USGS Benchmark Glaciers in context of global glacier studies
Glaciers and Landscape Change
Mountain glaciers are dynamic reservoirs of frozen water, deeply interconnected with their surrounding ecosystems. Glacier change in North America has major societal impacts, including to water resources, natural hazard risk, tourism disruption, fisheries, and global sea level change. Understanding and quantifying precise connections between changing glaciers, the surrounding landscape and climate...
Aerial photographs of South Cascade Glacier represent 57 years of change
Aerial photograph of South Cascade Glacier, WA taken August 13th, 1958 (before image) and October 14th, 2015 (after image).
Filter Total Items: 77
Ablation stakes on Gulkana Glacier
Ablation stakes on Gulkana Glacier, Alaska. Late summer fieldwork on Gulkana Glacier reveals ablation stakes emerging from the ice. Measurements of the change in the height of the snow and ice at these stakes is one aspect of determining glacier mass balance.
Ablation stakes on Gulkana Glacier, Alaska. Late summer fieldwork on Gulkana Glacier reveals ablation stakes emerging from the ice. Measurements of the change in the height of the snow and ice at these stakes is one aspect of determining glacier mass balance.
Collecting Field Data at Gulkana Glacier
USGS scientists collect field data at Gulkana Glacier in the eastern Alaska Range. The checkerboard sampling pattern in the foreground indicates where snow pit density measurements were collected.
USGS scientists collect field data at Gulkana Glacier in the eastern Alaska Range. The checkerboard sampling pattern in the foreground indicates where snow pit density measurements were collected.
Gulkana Glacier weather station
A scientist checks data collection on multiple sensors at the Gulkana Glacier weather station where snow blankets the glacier surface.
A scientist checks data collection on multiple sensors at the Gulkana Glacier weather station where snow blankets the glacier surface.
View South from Wolverine Glacier
View South from Wolverine Glacier
Ablation Stake on Wolverine Glacier
An ablation stake which began the summer below the surface of the snow is shown here in the fall, extending far above bare ice surface of Wolverine Glacier, Alaska. A USGS scientist carries a portable steam drill, used to install the stakes in the glacier.
An ablation stake which began the summer below the surface of the snow is shown here in the fall, extending far above bare ice surface of Wolverine Glacier, Alaska. A USGS scientist carries a portable steam drill, used to install the stakes in the glacier.
Hydrologic Technician measuring discharge. South Cascade Glacier, WA.
Hydrologic Technician measuring discharge. South Cascade Glacier, WA.Hydrologic Technician Dan Restivo of the USGS Washington Water Science Center admires the view while measuring discharge at the base of the South Cascade Glacier station 12181090 South Cascade Middle Tarn near Marblemount, WA.
Hydrologic Technician measuring discharge. South Cascade Glacier, WA.
Hydrologic Technician measuring discharge. South Cascade Glacier, WA.Hydrologic Technician Dan Restivo of the USGS Washington Water Science Center admires the view while measuring discharge at the base of the South Cascade Glacier station 12181090 South Cascade Middle Tarn near Marblemount, WA.
Taku Glacier, Alaska retreat
2019 Juneau Icefield Research Program (JIRP) students during a four day and 83 kilometers ski traverse across Taku Glacier, carrying all their food, water, clothing, tents, and science gear as they help measure the mass balance along the way.
2019 Juneau Icefield Research Program (JIRP) students during a four day and 83 kilometers ski traverse across Taku Glacier, carrying all their food, water, clothing, tents, and science gear as they help measure the mass balance along the way.
Glacier mass balance measurements on Taku Glacier, Alaska
Glacier mass balance measurements on Taku Glacier, AlaskaStudents Stacey Edmonsond (left) and Audrey Erickson (right) of the Juneau Icefield Research Program, measuring glacier mass balance at the flow divide of Taku and Mendenhall glaciers during the summer of 2019
Glacier mass balance measurements on Taku Glacier, Alaska
Glacier mass balance measurements on Taku Glacier, AlaskaStudents Stacey Edmonsond (left) and Audrey Erickson (right) of the Juneau Icefield Research Program, measuring glacier mass balance at the flow divide of Taku and Mendenhall glaciers during the summer of 2019
Firn core with an ice lens collected on Gulkana Glacier, Alaska.
Firn core with an ice lens collected on Gulkana Glacier, Alaska.Firn core with an ice lens collected on Gulkana Glacier during spring 2019 mass balance field work. Gulkana Glacier is located along the south flank of the eastern Alaska Range.
Firn core with an ice lens collected on Gulkana Glacier, Alaska.
Firn core with an ice lens collected on Gulkana Glacier, Alaska.Firn core with an ice lens collected on Gulkana Glacier during spring 2019 mass balance field work. Gulkana Glacier is located along the south flank of the eastern Alaska Range.
Researcher on Sperry Glacier
Researcher holds an ablation stake and winter snow probe during spring mass balance field work on Gulkana Glacier, AK.
Researcher holds an ablation stake and winter snow probe during spring mass balance field work on Gulkana Glacier, AK.
View of Nellie Juan Glacier from Wolverine Glacier
View of Nellie Juan Glacier from Wolverine GlacierView of Nellie Juan Glacier from Wolverine Glacier
View from Wolverine Glacier from Helicopter
View from Wolverine Glacier from Helicopter
A windblown stand of hemlock trees at the Wolverine Glacier field site
A windblown stand of hemlock trees at the Wolverine Glacier field siteA windblown stand of hemlock trees at the Wolverine Glacier field site
A windblown stand of hemlock trees at the Wolverine Glacier field site
A windblown stand of hemlock trees at the Wolverine Glacier field siteA windblown stand of hemlock trees at the Wolverine Glacier field site
Satellite image of Taku Glacier in October 1, 2018
Satellite image of Taku Glacier in October 1, 2018Satellite image of Taku Glacier in October 1, 2018. The Norris Glacier can be seen on the lower left hand corner and the Hole-in-the-Wall Glacier in the upper center portion of the image. Citation: McNeil, C. J., and Baker, E.
Satellite image of Taku Glacier in October 1, 2018
Satellite image of Taku Glacier in October 1, 2018Satellite image of Taku Glacier in October 1, 2018. The Norris Glacier can be seen on the lower left hand corner and the Hole-in-the-Wall Glacier in the upper center portion of the image. Citation: McNeil, C. J., and Baker, E.
Scientists use ground penetrating radar on Wolverine Glacier, AK
Scientists use ground penetrating radar on Wolverine Glacier, AKResearchers use ground penetrating radar to determine the depth of the snow on Wolverine Glacier. Wolverine Glacier is in the Kenai Mountains on the coast of south-central Alaska. In 1966 scientists with the USGS began making direct measurements of surface mass balance at Wolverine Glacier, one of the "benchmark glaciers" in Alaska.
Scientists use ground penetrating radar on Wolverine Glacier, AK
Scientists use ground penetrating radar on Wolverine Glacier, AKResearchers use ground penetrating radar to determine the depth of the snow on Wolverine Glacier. Wolverine Glacier is in the Kenai Mountains on the coast of south-central Alaska. In 1966 scientists with the USGS began making direct measurements of surface mass balance at Wolverine Glacier, one of the "benchmark glaciers" in Alaska.
Sperry Glacier perimeter: 1966,1998, 2005, 2015.
This image shows the perimeter of Sperry Glacier in Glacier National Park in 1966,1998, 2005, and 2015.
This image shows the perimeter of Sperry Glacier in Glacier National Park in 1966,1998, 2005, and 2015.
Wolverine Glacier
A researcher locates an ablation stake near a crevasse on Wolverine Glacier. These collapsible poles are used to measure snow and ice melt on the glacier surface.
A researcher locates an ablation stake near a crevasse on Wolverine Glacier. These collapsible poles are used to measure snow and ice melt on the glacier surface.
Sperry Glacier snow core
Snow core measurements help scientists determine snow density, which is used to determine the mass balance of Sperry Glacier.
Snow core measurements help scientists determine snow density, which is used to determine the mass balance of Sperry Glacier.
Researchers on Sperry Glacier
Researchers get organized to begin mass balance field work after skiing to Sperry Glacier.
Researchers get organized to begin mass balance field work after skiing to Sperry Glacier.
Researchers at Sperry Glacier
Researchers get organized to begin mass balance field work after skiing to Sperry Glacier.
Researchers get organized to begin mass balance field work after skiing to Sperry Glacier.
Measurement stakes are carried across Sperry Glacier in Glacier NP.
Measurement stakes are carried across Sperry Glacier in Glacier NP.Measurement stakes are carried across Sperry Glacier in Glacier National Park, Montana, during spring mass balance field work in 2019.
Measurement stakes are carried across Sperry Glacier in Glacier NP.
Measurement stakes are carried across Sperry Glacier in Glacier NP.Measurement stakes are carried across Sperry Glacier in Glacier National Park, Montana, during spring mass balance field work in 2019.