UW Researcher Part of Team That Finds Ice in Tetons’ Rock Glaciers Persisting Better Than on Exposed Glaciers, Snowfields

A University of Wyoming researcher was part of a team that determined ice found in rock glaciers in the Teton Range persists in a warming climate, providing a sustained cold-water streamflow, as opposed to exposed ice glaciers and snowfields, where ice melts more rapidly.

"The major crux is that rock glaciers are protected from rising atmospheric temperatures because they are insulated by debris that lies over the top of them. This is like throwing a down comforter over the top of an ice block on a hot day," says Lusha Tronstad, lead invertebrate zoologist with UW's Wyoming Natural Diversity Database (WYNDD). "An ice block in the sun will melt faster than one with the down comforter over the top because it is insulated from the warmer temperatures."

Tronstad was co-author of a paper titled "Accelerating Glacier Recession Contrasts Rock Glacier Stability in a Temperate Mountain Range" that was published today (July 1) in Science Advances, the American Association for the Advancement of Science's open access multidisciplinary journal. The journal publishes impactful research papers and reviews in any area of science, in both disciplinary-specific and broad, interdisciplinary areas.

The paper's lead author was Ashlesha Khatiwada, a Ph.D. candidate in the Department of Geosciences at Colorado State University. Other contributors to the paper were from Utah State University; Missouri State University; Utrecht University in Utrecht, Netherlands; the Swiss Federal Institute of Technology in Zurich, Switzerland; and Occidental College.

Simeon Caskey, physical science branch chief at Grand Teton National Park, and Madeline Grubb, a former physical science technician at Grand Teton National Park, also contributed.

Glaciers, rock glaciers and perennial snowfields are important components of mountain ecosystems that provide microclimates for animals and deliver critical nutrients and cold water to downstream habitats, according to the study. Summer snow and ice melt sustain these critical cold habitats.

However, the rapid retreat of glaciers and perennial snowfields in the Teton Range is altering alpine hydrology and ecosystem stability. Recent warming of meltwater sources has already contributed to the listing of bull trout and two stonefly species under the U.S. Endangered Species Act, according to the study.

The study used historical and contemporary data spanning from 1967-2024 to assess elevation change for glaciers, rock glaciers and perennial snowfields, as well as the thermal response in streams in the Teton Range, located in northwest Wyoming.

Tronstad and two of the paper's co-authors -- Scott Hotaling, an assistant professor of watershed sciences at Utah State University, and Deb Finn, an associate professor of biology and the Roy D. Blunt Life Science Endowed Professor at Missouri State University -- have been engaged in monitoring for the past 11 years.

"We have been monitoring 12 streams draining rock glaciers, exposed ice glaciers and perennial snowfield since 2015," says Tronstad, mentioning why she is involved with the paper. "We have been collecting continuous stream temperature data since that time."

According to study data, glaciers and snowfields thinned between 2014-2022 at a seven-fold increase compared to 1967-2014, with ice thinning driven by warming summer temperatures. In contrast, rock glaciers are near equilibrium and saw no change in the rate of ice melt from 1967-2022.

These results suggest that the recent acceleration in glacier thinning is primarily driven by warmer summers rather than a decrease in winter snowfall, the study says. As glaciers continue to diminish and disappear, the primary source of meltwater input is expected to shift from glacier to rock glacier sources, according to the study. This transition may alter streamflow timing, sediment and nutrition dynamics, and aquatic habitat stability.

"We have been saying that we predict rock glaciers and other forms of subterranean ice will remain on the landscape longer than exposed ice glaciers," Tronstad says. "But, until now, we did not have definitive data to support that statement. The lidar evidence we present in this paper now demonstrates that rock glaciers in the Teton Range are changing far less than exposed ice glaciers."

The research was funded by a National Science Foundation grant.

About the Wyoming Natural Diversity Database

WYNDD offers the most complete source of data for species and vegetation communities of management concern in Wyoming. Its mission is threefold: Identify and rank species that are priorities for management in Wyoming; amass existing data and develop new data for species needing management efforts, and for Wyoming vegetation types; and distribute these data upon request, under the philosophy that the best decisions regarding natural resources will be made only when everyone has access to complete and current scientific data.