From 23% less in the northern Alps to a decrease of almost 50% on the southwestern slopes: Between 1920 and 2020, snowfall across the entirety of the Alps has decreased on average by a significant 34%. The results come from a study coordinated by Eurac Research and were published in the International Journal of Climatology. The study also examines how much altitude and climatological parameters such as temperature and total precipitation impact on snowfall.
The data on seasonal snowfall and rainfall was collected from 46 sites throughout the Alps, the most recent of which was collected from modern weather stations, and the historical data was gathered from handwritten records in which specially appointed observers recorded how many inches of snow were deposited at a given location.
By collaborating with numerous meteorological offices, environmental agencies, volunteer associations, and the University of Trento, it was possible to combine all this information, which was then interpreted by the Eurac Research-led team, who created a comprehensive picture of snowfall in the Alps between 1920 and 2020.
“There is a markedly negative trend in terms of fresh snowfall in the Alps with an overall decrease of about 34%. In particular, a notable decrease was observed after 1980. This date also coincides with an equally sharp increase in temperatures,” explains Michele Bozzoli, environmental meteorologist at Eurac Research and first author of the study. “The most negative trends concern locations below an altitude of 2,000 meters and are in the southern regions such as Italy, Slovenia and part of the Austrian Alps.
In the Alpine areas to the north such as Switzerland and northern Tyrol, the research team observed the extent to which altitude also plays a central role. Although there has been an increase in precipitation during the winter seasons, at lower altitudes, snowfall has increasingly turned to rain as temperatures have risen. At higher elevations, however, thanks to sufficiently cold temperatures, snowfall is being maintained. In the southwestern and southeastern areas, temperatures have risen so much that even at higher elevations, rain is frequently taking over snowfall.
“Snow is crucial as a water reservoir. It feeds glaciers, mountain streams, and as it melts slowly in spring, replenishes water reserves gradually. The decrease in snow has an impact not only on winter sports, but also on all activities and processes that rely on water. This aspect can no longer be ignored in the policy planning of water management,” Bozzoli concludes.
More information: Michele Bozzoli et al, Long‐term snowfall trends and variability in the Alps, International Journal of Climatology (2024). DOI: 10.1002/joc.8597
Provided by Eurac Research