A collaborative effort by the research community has enabled the very first Alpine-wide assessment of station snow depth – and found decreases in snow depth in spring across all altitudes and regions over the last 50 years.

New research published in the journal The Cryosphere evaluates snow data for the period 1971-2019 from more than 2000 measuring stations in Austria, France, Germany, Italy, Slovenia, and Switzerland, making it the first Alpine-wide assessment of station snow depth. The study, coordinated by Eurac Research, is the result of an international collaborative research effort contributed to by over 30 partners.

"This study analyses the snow cover in the Alps quantitatively, for the first time and for the entire mountain range. It shows the distribution of snow - which, we have seen, accurately reflects the major climatic zones in the Alps - and what has changed over the past 50 years," explains Michael Matiu, researcher at Eurac Research's Institute for Earth Observation, who conceived the study with colleague Alice Crespi.

The researchers manually collated the snow data and analysed the information using a uniform method in order to compare the changes in snow depths and snow cover over the last fifty years. According to the study authors, the results provide a reliable basis for describing snow trends up to an altitude of 2,000 meters; above this height, too few measuring stations are present to extract reliable information for the whole of the Alpine region.

A Consequence of Climate Change

The results show that snow in the European Alps is unevenly distributed and is not decreasing everywhere to the same extent. In the Southern Alps, which already have less snow than their northern counterparts, snow depth below 2000 meters decreased significantly more in most months than in the Northern Alps. However, while regional trends sometimes differ considerably, the study found that decadal variability is similar throughout the Alpine region: the 1970s and 1980s were generally snowy, followed by a period of snow scarce winters in the late 1980s and early 1990s. Since then, although snow depths have increased again to some extent, they have not reached the levels of the 1970s. What is more, almost all stations across all regions and altitudes recorded a decrease in snow cover in spring.

"While in winter there is a wide range of variation in trends depending on location and altitude, even with isolated increases in snow at higher altitudes, in spring, almost all the stations recorded decreases.” – Alice Crespi, Eurac Research Institute for Earth Observation.

Between 1971 and 2019, the winter snow season shrunk by an average of 22-34 days in Alpine areas below 2,000 metres. The researchers also found that snow on the ground tends to appear later in winter and disappear earlier in spring. This, Matiu says, can be attributed to climate change: “In this study we did not look explicitly at the formal attribution, but it is clear that snow melts earlier and faster due to higher temperatures and that precipitation occurs as rain rather than snow.”

This study was overseen by Eurac Research and involved more than thirty partners from Austria, France, Germany, Italy, Slovenia, and Switzerland. MRI SLC member Samuel Morin is among the paper's authors.

The data set resulting from this study has now been made freely accessible to support future research, and can be found here.

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Cover image by Jörg Vieli.

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