Past changes in natural and managed snow reliability of French Alps ski resorts from 1961 to 2018

Abstract. Snow reliability is a key climatic impact driver for the ski tourism industry, for which there is more literature regarding future projections than past observed impacts. This study provides an assessment of past changes in natural and managed snow cover reliability from 1961 to 2018 in the French Alps. In particular, we used snowmaking investment figures to infer the evolution of snowmaking coverage at the ski resort scale for 16 ski resorts in the French Alps. We find different benefits of snow management to reduce the variability and long term decrease in snow cover reliability because of the heterogeneity of the snowmaking deployment trajectories across ski resorts. The frequency of challenging conditions for ski resort operation over the 1991–2018 period increased in November and February to April compared to the reference period 1961–1990. In general, snowmaking had a positive impact on snow reliability, especially in December to January. While for the highest elevation ski resorts, snowmaking improved snow reliability for the core of the winter season, it did not counterbalance the decreasing trend in snow cover reliability for lower elevation ski resorts and in the spring.