The USGS Benchmark Glacier Project

Climate change is altering Earth's glaciers. Mountain glaciers, especially in Alaska, contribute significantly to sea level rise. Before reaching the sea, their meltwater supplies water for drinking, agriculture, recreation and hydropower, and glacier change affects mountain hazards. This page summarizes a U.S. Geological Survey (USGS) fact sheet.

Why glaciers matter downstream

• Late-summer water: glaciers release meltwater in late summer, keeping streams flowing between spring snowmelt and fall rain.
• Cold water for wildlife: glaciers are linked to downstream ecosystems, providing cold water critical for salmon and other aquatic habitats.
• Changing rivers: glacier loss alters seasonal streamflow, water chemistry and temperature, challenging water managers, ecosystems and communities that depend on these frozen reservoirs.

For decades, key glaciers across western North America have been closely monitored, and their consistent records serve as benchmarks for understanding how glaciers respond to climate and affect ecosystems and hydrology.

The Wolverine Glacier research hut, Alaska. Photo by Louis Sass, USGS.

Five benchmark glaciers

The USGS Benchmark Glacier sites span middle to high latitudes and very different climates, from inland to coastal, giving a broad sample of how glaciers across the continent respond to climate. Four of them are reference glaciers in the World Glacier Monitoring Service's international network, and their data appear regularly in international climate assessments. The long records capture both seasonal and year-to-year variation.

USGS Benchmark Glaciers (black squares) across the glacier-covered regions of North America (blue). USGS figure; glacier extents from the RGI Consortium (2015).

In 2019 the project standardized its field practices and data processing, so estimates of glacier change can be compared across the continent — adding value beyond any single glacier's record. Decades of this research help project future glacier change, guiding sea level and water resource planning.

How glaciers are measured

• USGS scientists visit each site every spring and fall.
• Snow accumulation is measured in snow pits and snow cores.
• Summer melt is measured at stakes set into the glacier surface and revisited each year.
• Satellite imagery tracks change across whole mountain ranges.

Together these track yearly changes in both climate and glacier mass. Field measurements are costly and hard to make, but they are essential for continuity and for checking newer remote sensing methods.

Scientists measure snow accumulation and density at Gulkana Glacier, April 30, 2020. USGS photo.

Looking ahead

The USGS is layering new technologies — high-performance computing and satellite imagery — onto decades of field glaciology to understand glacier change across climate zones. The resulting information serves water resource planning and other scientists working on species habitat, ecosystem function, glacier geophysics, oceanography and resource management.

Sources

• U.S. Geological Survey: "U.S. Geological Survey Benchmark Glacier Project," Fact Sheet 2022–3050.
• Works cited include Zemp and others (2015, 2019); Fountain and others (1997); O'Neel and others (2019); Curran and Biles (2021); Wainwright and Weitkamp (2013); Giersch and others (2017); and Matthes (1939).