U.S. Glaciers Lost One-Third of Volume Since 1950
New research confirms widespread glacial decline across the contiguous United States, with severe losses in the Sierra Nevada.
Updated on Oct. 12, 2026 in Geography
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A study analyzing U.S. Geological Survey inventories and satellite imagery indicates that glaciers in the contiguous United States have lost one-third of their total volume and area since the mid-twentieth century. Researchers documented a net disappearance of 398 glaciers, leaving 1,331 remaining across the country.
Why it matters
The study highlights how warming temperatures are rapidly degrading glacial resilience, particularly in smaller, vulnerable sub-ranges like the Sierra Nevada. These findings underscore the accelerating trajectory of mass loss as glaciers adjust to current climatic conditions.
The study shows a 77% decrease in Sierra Nevada glacial volume since the 1970s and an 88% loss of total glacial area in the Trinity Alps. Nationally, while 398 glaciers vanished, the North Cascades bucked the trend by increasing from 668 to 706 glaciers over the same period.
The players
U.S. Geological Survey
The federal agency providing the scientific data and historical glacier inventories used to map current ice depletion.
The details
Researchers compiled the data by comparing historical U.S. Geological Survey records against modern aerial and satellite imagery taken between 2013 and 2019. By cataloging ice mass across the Western United States, the study identified that glaciers in the Sierra Nevada are increasingly fragile due to warmer, drier conditions. This approach allows for a precise regional accounting of physical ice decline by overlaying geographic data sets to map changes in perimeter and thickness over time.
Timeline
Mid-twentieth century serves as the baseline period for total U.S. glacial decline.
The 1970s marked the baseline period for the Sierra Nevada glacier count.
2013-2019 represents the most recent data range used in the study.
2020-2022 was identified as a drought period and excluded from the study data.
The Tech Race
This research provides an updated assessment of glacial stability relative to the baseline established by the U.S. Geological Survey glacier inventories. It establishes a new, comprehensive metric for quantifying ice mass loss that differentiates between the resilient North Cascades and the rapidly melting Sierra Nevada.
The findings primarily serve as a critical reference for environmental planners and water resource managers tracking regional hydrology. No immediate consumer-facing changes are expected, but the data informs long-term projections regarding water availability and ecosystem management.
The takeaway
The rapid loss of ice in the Sierra Nevada and Trinity Alps marks a significant departure from historical trends, indicating that smaller mountain glaciers are highly susceptible to warming. Watch for future assessments of the North Cascades to see if that region's recent glacial growth persists under continued climatic pressure.
Further reading
For more information on regional landscape changes and climate indicators, visit the Geography section.
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