Assessing the impacts of climate change on snow avalanche-induced risk in alpine regions

Climate change is a global challenge with serious impacts on human populations. Numerous studies have highlighted the impacts of climate change on natural hazard processes and associated risks for communities. Understanding future hazard and risks is crucial for effective risk management. This study focuses on assessing snow avalanche risks for inhabited areas in the context of climate-induced changes. By using hazard scenarios based on CH2018 climate projections and the RAMMS avalanche model, we generated large-scale hazard indication maps for future avalanche hazards. By employing the open-source probabilistic risk assessment platform CLIMADA, along with building data and vulnerability functions, we estimated risks for the present time and two future time frames: mid-century (2060) and the end of the century (2085). An uncertainty and sensitivity analysis complemented the study to account for potential fluctuations in model assumptions. Our mean-based approach, considering different CH2018 model chains, indicates an overall decline in avalanche risks for the future. The average annual impact for the medium (100-year return period) scenario decreases from 2.73 million CHF/Year to 1.75 million CHF/Year in mid-century, to 0.69 million CHF/Year by end of the century. This reduction is driven by assumed decreases in snow accumulation, rising snowpack temperatures, and a rising snowline. To cover more extreme developments, we have also examined boundary model chains, which suggest that future risks can both increase and decrease depending on minimum or maximum extreme precipitation. Within our model assumptions, both showed a general trend of decreasing affected objects towards the end of the century. In the extreme minimum snowfall scenario risk decreases from 1.85 of today to 0.3 million CHF/Year in mid-century and to 0.18 million CHF/Year by the end of the century. On the other hand, in the extreme maximum snowfall scenario risk increases to 4.29 million CHF/Year in mid-century but also decreases to 2.01 million CHF/Year by the end of the century. In the maximum snowfall scenarios, the reduction is mostly driven by a rising snowfall threshold and rising snow cover temperatures. It is worth noting that some individual objects depending on their location may remain at consistently high avalanche risk despite climate change. This study provides a valuable tool for decision-makers to compare future risk scenarios with the present situation, supporting effective mitigation and adaptation strategies to address the challenges of climate change. By providing risk maps and identifying potential future risk hot spots, our approach contributes to enhancing community resilience and protecting their assets in a changing climate.