Climate change is anticipated to significantly alter snowfall patterns across the globe, and the European Alps, a region heavily reliant on winter tourism and water resources, are particularly vulnerable. A recent study leveraging high-resolution regional climate models (RCMs) within the EURO-CORDEX initiative provides a detailed look into these future changes, utilizing what can be termed “Euro Snow Models” to project snowfall trends throughout the 21st century.
This research employed fourteen different combinations of global and regional climate models, targeting a 12 km resolution, and considered two distinct emission scenarios to assess snowfall changes. Since raw snowfall data isn’t consistently available from all RCMs, a novel method was used to differentiate snowfall from total precipitation. This method factors in near-surface temperatures and accounts for the complex subgrid-scale topography of the Alps, enhancing the accuracy of snowfall estimations.
The reliability of these “euro snow models” was rigorously evaluated against observational data. The models demonstrated a good ability to capture the seasonal snowfall cycle and its variation with elevation. However, the evaluation also revealed a tendency for the models to overestimate snowfall, especially at higher altitudes. To address this, a specialized bias adjustment technique was applied, separately correcting for temperature and precipitation biases in the RCM outputs, leading to more refined snowfall projections.
Looking ahead, the projections consistently point towards a considerable decrease in snowfall across most of the Alps under both emission scenarios studied. Averaged across the entire domain and multiple models, the mean snowfall from September to May is projected to decline by 25% under the RCP4.5 scenario (moderate emissions) and a more drastic 45% under RCP8.5 (high emissions) by the end of the century. Lower elevation areas in the Alpine forelands are expected to experience even more severe reductions, potentially exceeding 80%.
These substantial decreases are primarily driven by rising temperatures due to climate change. This warming trend leads to a significant reduction in snowfall frequency and the proportion of precipitation falling as snow rather than rain. Heavy snowfall events are also projected to become less frequent.
Interestingly, the study highlights a nuanced picture at high elevations. Despite the overall decrease in snowfall fraction, these regions might see slight increases in snowfall during midwinter under both emission scenarios. This seemingly paradoxical increase can be attributed to a general rise in winter precipitation and a shift in temperature regimes. As temperatures increase, climatologically very cold areas transition into a temperature range that actually favors higher snowfall intensities, at least temporarily.
The study emphasizes that the percentage changes in snowfall are generally consistent regardless of the specific post-processing method applied to the RCM data, whether using raw snowfall, separated snowfall, or bias-adjusted snowfall. However, the absolute values of snowfall changes can vary depending on the method used.
In conclusion, “euro snow models” paint a concerning picture for the future of snowfall in the European Alps. While high-altitude regions may experience some short-term buffering, the overwhelming trend is a significant reduction in snowfall across the Alps, driven by climate change and rising temperatures. These findings have profound implications for water management, winter tourism, and the delicate ecosystems of this iconic mountain range.
