Past changes in natural and managed snow reliability of French Alps ski resorts from 1961 to 2019

Abstract

Abstract. Snow reliability is a key climatic impact driver for the ski tourism industry, although there are only a few studies addressing past changes in snow reliability in ski resorts accounting for snow management practices (grooming and snowmaking, in particular). This study provides an assessment of past changes in natural and managed snow cover reliability from 1961 to 2019 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, which we used together with a detailed snow cover modelling system driven by a local atmospheric reanalysis. 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 1991–2019 period increased in November and February to April compared to the 30-year 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.