Elevation-dependent snow cover changes across Switzerland in the 21st century

Snow provides numerous ecosystem and economic services, such as hydropower generation, regulation of stream temperature, and winter tourism. Despite projected increases in winter precipitation, warming temperatures are expected to reduce snowfall and shift precipitation toward rainfall, fundamentally changing snowpack accumulation dynamics, and the associated hazards such as rain-on-snow flooding. This highlights the need for accurate snow projections at locally relevant spatial scales.

Here, we present novel high-resolution (1x1 km²) daily projections of snow water equivalent (SWE) and snow depth for Switzerland, based on the recently released Climate CH2025 scenarios. SWE is simulated for an ensemble of 12 bias-adjusted regional climate models from the EURO-CORDEX initiative using a distributed temperature-index snow model, which is statistically nudged toward a reference SWE dataset (SPASS) – derived from the same model but debiased using data assimilation with observations from 1998-2024.

We project widespread SWE declines across Switzerland, with the largest percentage reductions at low elevations (<1000 m a.s.l.), and a transition from seasonal to ephemeral snowpacks at intermediate elevations. We further assess the added value of high-resolution snow simulations by comparing them with physically-based, but coarser (~12 km) raw EURO-CORDEX SWE projections. While both show consistent large-scale patterns, our higher resolution simulations reveal clearer elevation-dependent signals, especially in topographically complex mountainous landscapes, enabling robust estimation of locally relevant snow indicators. These results offer actionable insights for managing future snow-dependent resources in a rapidly warming climate.