As discussed in the Theia newsletter n°17 (available here in French), snow cover plays a fundamental role in the functioning of mountain ecosystems. In 2022, drought and heat waves considerably shortened the snow cover period at high altitudes.
To quantify this, Simon Gascoin, along with other experts from CNRS-CESBIO, used Theia snow products which give the snow-covered surface at 20 m resolution. They calculated the duration of snow cover between 1st June and 31th August, at 20 m spatial resolution, for each year since 2017, in the core areas of the four French high mountain National Parks: Pyrenees, Vanoise, Écrins, Mercantour (Figure 1).
Figure 1: Comparative Snow Cover in four French Natural Parks, 2018-2022, calculated from Theia Snow product.
The graph below (Figure 2) shows the average duration of snow cover above 2500m. In all four parks, the summer of 2022 was the least snowy since 2017. The anomaly in 2022 was slightly less pronounced in the Pyrenees (deviation from the median value = 51%) than in the Écrins (58%) or the Vanoise (56%). The Mercantour was almost devoid of snow this summer (difference from median value = 98%).