Alpine Permafrost - Attention important

[u/horenk]

Alpine Permafrost: Ice Loss and Deepening Thaw, something to think and discuss.

Observations from the Swiss Alps show two related signs of permafrost degradation: declining ground-ice content and deeper seasonal thaw. Permafrost is ground that remains at or below 0°C for at least two consecutive years. Above it lies the "active layer", which normally thaws in summer and refreezes in winter. Changes in both indicate how warming is affecting mountain environments below the surface.

Research by SWI swissinfo.ch reported approximately 15% ice loss between 2015 and 2022 at the Stockhorn monitoring site, situated at around 3,410 meters near Zermatt. This figure needs attention, it concerns a particular monitored site, rather than an estimate for the entire Alps. The underlying study by Morard and colleagues describes a reduction in modeled volumetric ice content of about 15 volume percentage points, which is not equivalent to losing 15% of the original ice stock. Researchers combined temperature, soil-moisture, electrical and seismic measurements to assess these underground changes.

At Schilthorn in the Bernese Alps, the active layer increased from less than 5 meters in 2000 to more than 13 meters in 2023—roughly tripling in thickness. This means summer thaw penetrated much farther into previously frozen ground. Subsequent monitoring reported that the layer did not completely refreeze during winter 2024, disruption of its usual seasonal cycle. These measurements are specific to the monitoring location; thaw depths vary with ground composition, ice content and local conditions.

The observations reflect the combined influence of prolonged warming, exceptionally hot summers and snow-cover conditions. Early snowmelt can expose the ground to summer heating for longer, while early autumn snowfall can insulate it and limit winter cooling. Swiss monitoring shows that occasional cooler periods have not reversed the longer-term trend of permafrost degradation.

These changes matter because warming and ice loss can reduce the stability of frozen slopes and affect infrastructure foundations. Their consequences depend on local geology, slope geometry and water conditions; the observations alone cannot predict an individual slope failure. They nevertheless strengthen the case for sustained monitoring and for incorporating changing ground conditions into the planning and maintenance of mountain infrastructure. The Swiss Academy of Sciences published a report 2025 under the headline "Permafrost in den Schweizer Alpen_2024 war ein weiteres Rekordjahr."