ROCK GLACIERS ARE BUFFERING ALPINE STREAM TEMPERATURE AGAINST WARMING IN THE HIGH TETON RANGE, USA

Climate change is dramatically altering alpine regions in the Rocky Mountains through recession of mountain glaciers and declines in seasonal snowpack. As meltwater sources decline and air temperatures rise, headwater streams should also become warmer. However, rates of change will depend on many factors, including the degree to which perennial ice sources are vulnerable or resistant to change. Indeed, rock glaciers--large masses of debris-covered ice are common in the Rocky Mountains and should be particularly resilient to atmospheric warming due to their insulating rock cover. Based on this, we can predict that streams fed by rock glaciers will experience slower warming than those fed by surface ice features (e.g., glaciers and perennial snowfields). To test this, we analyzed 10 years of monitoring data (2015-2024) for alpine streams in the Teton Range of Wyoming, USA that are fed by three hydrological sources (glacier, snowpack, rock glacier). Specifically, we addressed three questions: (1) Are alpine streams in the Teton Range warming? (2) If yes, how quickly are they warming? And, (3) does the rate of warming depend on hydrological source? Our results indicate clear, anthropogenic warming of alpine streams in the Teton Range, however this trend is being driven primarily by rapid warming of snowmelt-fed streams. The two stream types with significant perennial ice feeding them—glaciers and rock glaciers—have exhibited little no indication of warming over the study period. This result, however, may reflect different mechanisms as glaciers are losing large amounts of ice each year while rock glaciers have remained largely stable over the study period.