How Much is 12 Euros? Understanding Alpine Snowfall Projections
The European Alps, a crucial source of freshwater and a popular tourist destination, are experiencing significant changes in snowfall patterns due to climate change. Utilizing high-resolution regional climate model (RCM) data from the EURO-CORDEX initiative, researchers have projected substantial alterations in snowfall across the Alps by the end of the 21st century. This data, with a 12 km resolution, encompasses fourteen different global and regional climate model combinations and two emission scenarios: RCP4.5 and RCP8.5.
Projecting Snowfall in the Alps: Methodology and Findings
Due to inconsistencies in raw snowfall data availability from all RCMs, a novel method was employed to distinguish snowfall from total precipitation. This method leverages near-surface temperature conditions and accounts for subgrid-scale topographic variations. Validation against observational data demonstrates the RCMs’ capability to accurately simulate the seasonal cycle of snowfall and its dependence on elevation. However, a notable positive bias, particularly at higher elevations, was observed. This bias was partially mitigated through a specialized RCM bias adjustment targeting temperature and precipitation discrepancies.
Decreasing Snowfall Trends Across the Alps
Projections indicate a consistent decline in snowfall across most of the Alps under both emission scenarios. By the end of the century, the average September-May snowfall is projected to decrease by 25% under RCP4.5 and 45% under RCP8.5. Low-lying areas in the Alpine forelands could experience reductions exceeding 80%. These declines are primarily attributed to projected warming, resulting in a significant decrease in snowfall frequency and the proportion of precipitation falling as snow, even impacting heavy snowfall events.
Elevation-Dependent Variations in Snowfall Projections
Despite the overall decreasing trend, high-elevation regions may experience slight snowfall increases in midwinter under both scenarios. This seemingly paradoxical outcome is explained by increased winter precipitation and the upward shift of climatologically cold areas into temperature ranges conducive to higher snowfall intensities. While the overall fraction of precipitation falling as snow decreases, the increased total precipitation leads to more snow in these specific high-altitude zones.
Robustness of Snowfall Projections Across Different Methods
The percentage changes in snowfall indices remain consistent across different RCM postprocessing techniques, including raw, separated, and separated-bias-adjusted snowfall amounts. However, the absolute changes in snowfall can vary depending on the method used. This highlights the robustness of the overall trend while acknowledging the nuances in quantifying the precise magnitude of change. The projected changes underscore the need for adaptation strategies to address the potential impacts of reduced snowfall on water resources, tourism, and ecosystems in the Alps.