In the Alps, permafrost is generally found over 2300 m AMSL. It is estimated that about 15% of the Swiss alpine area or 4 to 6% of the Swiss territory is covered by permafrost (5).
Mountain permafrost is the dominating permafrost in Europe, because Arctic permafrost is found in Europe only in the northernmost parts of Scandinavia. Permafrost influences the evolution of mountain landscapes and affects human infrastructure and safety. Permafrost warming or thaw affects the potential for natural hazards, such as rock falls (e.g. at the Matterhorn in summer 2003) and debris flows (2). At least four large events involving rock volumes of more than 1 million m3 have occurred in the Alps during the past decade. Their effects on infrastructure have motivated the development of technical solutions to improve design lifetime and safety (3).
No specific projections on the behaviour of mountain permafrost are yet available, but changes in mountain permafrost are likely to continue in the near future and the majority of permafrost bodies will experience warming and/or melting (4). It is expected that the lower limit of permafrost in Switzerland will rise by 200-700 m if the temperature rises 1-2°C (6).
Systematic measurements have been carried out of European mountain permafrost temperatures from a latitudinal transect of six boreholes extending from the Alps, through Scandinavia to Svalbard. Boreholes were drilled in bedrock to depths of at least 100 m between May 1998 and September 2000. Geothermal profiles provide evidence for regional-scale secular warming, since all are nonlinear, with near-surface warm-side temperature deviations from the deeper thermal gradient (1).
Topographic effects lead to variability between Alpine sites. First approximation estimates, based on curvature within the borehole thermal profiles, indicate a maximum ground surface warming of +1°C in Svalbard, considered to relate to thermal changes in the last 100 years. In addition, a 15-year time series of thermal data from the 58 meter deep Murtèl–Corvatsch permafrost borehole in Switzerland, drilled in creeping frozen ice-rich rock debris, shows an overall warming trend, but with high-amplitude interannual fluctuations that reflect early winter snow cover more strongly than air temperatures (1).
Melting of permafrost destabilizes soils. In Switzerland, Engadine, Valais, Bernese Alps, and the Tödi region in Glarus are particularly affected (7). It is extremely likely that there will be problems related to infrastructure such as ski-lifts and protection against avalanches because these are fixed in the permafrost. For example, 15% of the Swiss mountain railways are built on permafrost (8). As a consequence, there will be a higher cost for repairs and restoration, in some cases causing the abandonment of the site. Moreover, hikers will be particularly affected by increased danger of falling rocks.
The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Switzerland.
- Harris et al. (2003)
- Noetzli et al. (2003); Gruber and Haeberli (2007), both in: EEA, JRC and WHO (2008)
- Philips et al. (2007), in: EEA, JRC and WHO (2008)
- EEA, JRC and WHO (2008)
- Keller et al. (1998), in: Matasci (2012)
- Bader and Kunz (2000), in: Matasci (2012)
- Matasci (2012)
- Noetzli and Vonder Mühll (2010), in: Matasci (2012)