Permafrost in the Alps – Long-term monitoring and evolution over two decades:
In cold mountain regions, permafrost exists above the forest line hidden in scree slopes, rock glaciers and steep bedrock slopes, where the ground temperature does not exceed 0°C all year round. Permafrost in mountain regions has been studied for some 40 years, especially in the European Alps and in Scandinavia. Long-term climate related monitoring is based on permafrost temperatures measured in boreholes, geo-electric surveys to detect changes in ground ice content and terrestrial geodetic surveys of rock glaciers to determine their creep velocity. Even though many of the time series only cover about two decades, the above methods have shown a spatially and temporally variable but consistent increase in permafrost temperatures, decrease in ground ice content and an increase in creep velocities at many sites in the European Alps. Events from permafrost regions such as rockfalls are documented for re-analysis for a better understanding of the relationship between permafrost degradation and instabilities of steep mountain flanks. Maintaining long-term measurements under the extreme conditions found in high mountains is a major challenge. In the future, new measurements and methods will complement the scientific observation strategies and coverage should be improved – both by means of simulations and by obtaining data from locations with difficult access as well as from less explored conditions and mountain regions.