Glacier of the Year 2025 – South Cascade Glacier, US

The WGMS objective of this activity started on the first World Day for glaciers on March 21, 2025 to highlight the beauty of glaciers around the world and honor the dedication of glaciologists who have been observing them for decades as a contribution to an internationally coordinated monitoring effort.

South Cascade Glacier is located in the Cascade Range in Washington, United States. It has been continuously monitored since 1952 and provides one of the longest uninterrupted records of glaciological mass balance in the Western Hemisphere.

Sunset illuminated Sentinel Peak with South Cascade Glacier, located in the Cascade Range, USA. South Cascade Glacier has the longest mass-balance record within the USGS Benchmark Glacier monitoring programme. Photograph from October 6, 2020: Source: U.S. Geological Survey.

“South Cascade Glacier exemplifies both the beauty of glaciers and the long-term commitment of dedicated scientists and volunteers who have collected direct field data to quantify glacier mass change for more than six decades”, says Caitlyn Florentine, Co-Investigator of the glacier from the U.S. Geological Survey.

The United States has a variety of natural resource assets, including glaciers in the states of Alaska, Washington, Oregon, California, Montana, Idaho, Wyoming, and Colorado. These frozen reservoirs produce cold meltwater that influences streamflow and can mitigate drought. Understanding glacier mass change requires direct field observations, because patterns of snow accumulation are complex and cannot be measured remotely at timescales relevant to decision making.

Glaciological research at South Cascade Glacier initiated during the International Geophysical Year (July 1957 to December 1958) and continues as part of the U.S. Geological Survey’s Benchmark Glacier Project (Florentine and Mckeon, 2021; (U.S. Geological Survey, Benchmark Glacier Program, 2016).

Research at South Cascade Glacier has produced technological and scientific breakthroughs in glaciology (e.g., Fountain, 1993; Hodge, 1976; Meier and Tangborn, 1965), provided a training ground for students, and involved scientists recognized by the International Glaciological Society, including Wendell Tangborn and Mark Meier. Current data collected at South Cascade Glacier continue to provide observational constraints that support modeling and remote-sensing studies.

References:

Florentine, C. E. and Mckeon, L. A.: U . S . Geological Survey Benchmark Glacier Project, U.S. Geol. Surv. Fact Sheet 2022-3050, 2021.

Fountain, A. G.: Geometry and flow conditions of subglacial water at South Cascade Glacier, Washington State, USA; an analysis of tracer injections, J. Glaciol., 39(131), 143–156, doi:10.1017/S0022143000015793, 1993.

Hodge, S. M.: Direct Measurement of Basal Water Pressures: a Pilot Study, J. Glaciol., 16(74), 205–218, doi:10.3189/s0022143000031543, 1976.

Meier, M. F. and Tangborn, W. V.: Net Budget and Flow of South Cascade Glacier, Washington, J. Glaciol., 5(41), 547–566, doi:10.3189/s0022143000018608, 1965.

U.S. Geological Survey, Benchmark Glacier Program, 2016, Glacier-wide mass balance and compiled data inputs (ver. 9.0, December 2024): U.S. Geological Survey data release, https://doi.org/10.5066/F7HD7SRF. [C:40, D:40]