Jaca, March 30, 2026. A study by five scientists, published in the March issue of the journal Cold Regions Science and Technology, has concluded that avalanches in the Pyrenees are becoming smaller, but also more frequent. The researchers examined 57 avalanche events recorded between 1910 and 2014 in the Canfranc Valley and found that climate variability, defined by the North Atlantic Oscillation (NAO), affects precipitation and temperatures, and therefore the likelihood of avalanches.

The study was carried out במסגרת the European LIFE Pyrenees4Clima project, which brings together the seven regions covered by the mountain range (Andorra, Aragon, Catalonia, the Basque Country, Navarre, Nouvelle-Aquitaine, and Occitanie) and is led by the Pyrenean Climate Change Observatory (OPCC-CTP). It starts from the premise that the Pyrenees are among the mountain cryosphere regions with the highest levels of avalanche activity in the world (Eckert et al., 2024). The paper is authored by five experts: Jaime Boyano Galiano, Alberto Muñoz Torrero, and Juan Antonio Ballesteros Cánovas, all three from the National Museum of Natural Sciences (MNCN-CSIC); Juan Ignacio López Moreno, from the Pyrenean Institute of Ecology (IPE-CSIC); and Osvaldo Franco-Ramos, from the Institute of Geography at the National Autonomous University of Mexico. This report comes after a particularly tragic winter, in which avalanches have claimed the lives of at least eight people in the Pyrenees, the most recent on March 18.

The study provides valuable information for risk assessment and the development of adaptive hazard management strategies in mountain environments affected by climate change. Specifically, it analyses the relationship between climate change and snow avalanche activity along the Estiviellas and Rinconada paths. Using historical records, dendrochronological analysis, geomorphological mapping, and climate data, researchers reconstructed 30 avalanche events in Estiviellas and 27 in Rinconada. The results show that the largest avalanches occurred more frequently in the second half of the 20th century, whereas in recent decades smaller but more frequent events have been recorded, confined to the upper slopes.

The research also highlights the importance of reforestation practices and structural mitigation measures implemented in the area since the beginning of the 20th century, which have reduced the severity of avalanche risk, thereby demonstrating their effectiveness.

Juan Antonio Ballesteros, one of the five authors of the study, explains how they have identified a trend whereby “smaller avalanches, located in higher areas, are becoming increasingly frequent and may affect protective infrastructures (dams, nets, etc.) that are designed precisely to mitigate the effects of large avalanches.”

“Climate change creates more variable and more extreme situations.”

In avalanches, “the temperature variable has an effect. There is a trend toward an increase in the number of small avalanches, meaning they are becoming more frequent. That said, large avalanches, although less frequent, will continue to occur. In the 20th century there were already several major avalanches that reached the bottom of the valley. Every 20 or 30 years there is an avalanche of some significance,” Ballesteros points out.

Climate change “creates more variable and more extreme situations, as happens not only with rainfall and temperature, but also with snow. As a result, the snowpack becomes more unstable, especially toward the end of winter. A more unstable snowpack can particularly affect winter sports activities.”

In a similar vein, Juan Terrádez, project manager at the OPCC, states: “At certain altitudes in the Pyrenees there is still limited instrumentation in place, and the available data series on these phenomena are relatively short and heterogeneous. Therefore, more information is still needed to identify statistically significant trends that clearly link extreme events to climate change.”

In any case, he adds, “climate change and climate variability influence avalanche dynamics and risk in the Pyrenees in several ways. They change the frequency, type, and time of year in which avalanches occur. Natural climate variability, together with that induced by human activity, is making weather conditions during the avalanche season in the Pyrenees increasingly variable, depending on the state and stability of the snowpack. Depending on how the different snow layers are structured, problems of slippage between them may increase.”

Terrádez concludes that “climate change in the Pyrenees tends to reduce the total amount of snow, but at the same time it may increase the instability of the remaining snowpack and, therefore, the seasonal and typological variability of avalanches: there will be fewer events at lower elevations, but greater uncertainty and more episodes at higher altitudes, with a higher proportion of wet avalanches than dry ones.” Knowledge is the basis for acting more effectively, and we must continue working to define adaptation measures to climate change.

“Other studies from the Pyrenees4Clima project”

Another of the organisations working on the European LIFE Pyrenees4Clima project is Météo-France. Its Deputy Scientific Director, Jean-Michel Soubeyroux, points out that there are “very few specific studies on avalanches in the Pyrenees.” Nevertheless, beyond the question of how avalanche risks are evolving with climate change, “some research also focuses on mitigating their effects, reducing the vulnerability of critical infrastructure, exposure, and many other aspects.” Within the Pyrenees4Clima project, two lines of work are being developed: “the creation of snow-depth databases that make it possible to build more complete historical series on the evolution of the snowpack in the Pyrenees” and, on the other hand, “the updating of climate projections for snow cover in the Pyrenees.”

Another of the entities involved in the Pyrenees4Clima research is the European Grouping of Territorial Cooperation Pirineos-Pyrénées, which is responsible for the safety of the cross-border routes at El Portalet and the Bielsa-Aragnouet Tunnel. Santiago Fábregas, a member of the EGTC, echoes the work of the MCN researchers and the study’s conclusions, and stresses the “importance of collecting, interpreting and sharing snow and meteorological data with the different actors involved in the Pyrenees, in order to identify sites and situations that may pose an avalanche risk; passing this information on to meteorological services, road managers, ski resorts, mountain rescue services, municipal services, research bodies, federations, clubs, etc.”

He also points to the importance of understanding and recording the causes and effects of avalanches, “especially when they have caused injuries and/or significant damage to property and/or services. It is about carrying out something like an avalanche autopsy,” and learning from what happened in order to be better prepared for the immediate future.

En el marco del proyecto Pyrenées4clima, todos estos expertos siguen trabajando en ampliar el conocimiento sobre las nevadas y las avalanchas en los Pirineos, de modo que se puedan aumentar las medidas de adaptación y mejorar las condiciones de seguridad para las actividades humanas en la zona.