Projections of Mountain Snowpack Loss for Wolverine Denning Elevations in the Rocky Mountains

Abstract

Future reduction in mountain snowpack due to anthropogenic climate change poses a threat to many snow-adapted species worldwide. Mountain topography exerts a strong control on snowpack not only due to elevation but also through the effect of slope and aspect on the surface energy balance. We develop high-resolution projections of snowpack in order to provide improved, physically based estimates of the spatial distribution of future snowpack to inform species conservation efforts for the wolverine (Gulo gulo) in two study areas in the Rocky Mountains: one in Montana with known den sites and one in Colorado with recent wolverine activity and potential for reintroduction. Here we assess springtime snowpack loss in actual and potential denning areas under five future climate scenarios for the mid-21st century. Snowpack in April and May is likely to persist into the mid-21st century in the upper half of current denning elevations in all but the warmest future climate scenario, while large declines are projected for the lower half of the denning elevations. We gain new insight into the influence of topographical aspect on future snowpack and quantify the potential for enhanced snow persistence on north and east facing slopes under future scenarios that is only revealed in simulations where terrain slopes are resolved. Plain Language Summary Climate change and its effect on snow are a threat to high mountain ecosystems and species worldwide. The future of mountain snowpack is complex, with multiple drivers, and with a strong elevation dependence. What has received much less attention is the dependence on topographical aspect-how will the snowpack on north facing versus south facing slopes respond differently under climate change. In this paper we develop snow projections motivated by a conservation issue for the wolverine: the future of the springtime snowpack at elevations of observed and potential wolverine denning for two study areas in the Rocky Mountains by the mid-21st century. While there is significant snowpack loss in the lower half of denning elevations, the upper denning elevations retain springtime snowpack, supporting conservation actions through midcentury in these regions.

Projections of North American snow from NA-CORDEX and their uncertainties, with a focus on model resolution

“…Vavrus, 2007). It also provides an important habitat for wildlife that are adapted to living in snow conditions (Campbell et al, 2005;Barsugli et al, 2020). Seasonal snow accumulation is a natural reservoir for water storage and the timing and amount of snowmelt is critical for water supply (Barnett et al, 2005), agriculture (Qin et al, 2020) and hydropower production (Markoff and Cullen, 2008.…”

Uncertainty, Complexity and Constraints: How Do We Robustly Assess Biological Responses under a Rapidly Changing Climate?

“…For a topographically complex region, such as the Rocky Mountains, it is also important to run these models at a much finer spatial resolution to capture the true effects of elevation, slope, and topographical aspect. Barsugli et al [60] demonstrated enhanced snow persistence on the north and east facing slopes in the Rocky Mountains under future climate scenarios by mid-21st century by running a hydrological model at 250-m spatial resolution, which resolved the terrain slopes. In our projects, we often quantify future changes in mountain snowline based on a strong observed relationship between the atmosphere freezing level and surface air temperature.…”

Uncertainty, Complexity and Constraints: How do We Robustly Assess Biological Responses Under a Rapidly Changing Climate?

“…For a topographically complex region, such as the Rocky Mountains, it is also important to run these models at a much finer spatial resolution to capture the true effects of elevation, slope, and topographical aspect. Barsugli et al [44] demonstrated enhanced snow persistence on the north and east facing slopes in the Rocky Mountains under future climate scenarios by mid-21 st century when they ran a hydrological model at 250-m spatial resolution, which allowed them to resolve the terrain slopes. One aspect of snow-related information that we have developed in our projects is to assess future changes in mountain snowline based on a strong observed relationship between the atmosphere freezing level and surface air temperature.…”