Projections of North American Snow from NA-CORDEX
In a warming climate, the characteristic of snow will likely change in fundamental ways, therefore compelling societal need for projections of snow. However, many stakeholders require climate change information at finer scales than GCMs can provide. The North American Coordinated Regional Downscaling Experiment (NA-CORDEX) provides an ensemble of regional climate model (RCM) simulations at ~0.5º and 0.25º. This study examines differences in end-of-century projections of snow with an eye toward the role that model resolution plays in the climate change response and uncertainty. We consider three climate model ensembles 1) NA-CORDEX driving GCMs, 1) NA-CORDEX 0.5º simulations, and 3) NA-CORDEX 0.25º simulations. We first evaluate against an observational ensemble to assess bias. We then examine continental changes in snow cover extent, snow water equivalent, and snow cover duration over North America and within 3 sub-basins, the Northeast, Northern Canada, and the Intermountain West.
This work demonstrates that the broad patterns of change are similar across the RCMs and GCMs: snow cover retreats, snow mass decreases, duration of snow cover season decreases. But the spatial detail, magnitude, percent, and uncertainty of the change vary between the GCMs and RCMs, but not between the RCMs with different resolutions.
This study examines future changes in snow over North America from the North American Coordinated Regional Downscaling Experiment (NA-CORDEX) and their driving GCMs. NA-CORDEX provides an ensemble of climate simulations at 0.5º and 0.25º and is designed to help serve the climate impacts and adaptation communities. We find that the broad patterns of change are similar across RCMs and GCMs: snow cover retreats, snow mass decreases everywhere except at high latitudes, and the duration of the snow-covered season decreases. Regionally, the spatial details, magnitude, percent, and uncertainty of future changes vary between the GCM and RCM ensemble but are similar between the two resolutions of the RCM ensembles. An increase in winter snow amounts at high latitudes is a robust response across all ensembles. Percent snow losses are found to be more substantial in the GCMs than the RCMs over most of North America, especially in regions with high-elevation topography. Specifically, percent snow losses decrease with increasing elevation as the model resolution becomes finer.