Permafrost is a feature of the high-mountain landscape in Switzerland, where it forms a part of many attractive geological structures. Permafrost itself can not be seen, which is perhaps why mythical-like characteristics are sometimes attributed to it. Permafrost refers to a situation in which substrate material (e.g. rock, rubble) remains below 0°C all year round for at least two consecutive years. Permafrost usually has an active layer of ground above it that displays sharp temperature fluctuations throughout the year and can thaw during the warmer months. Permafrost can be found in many different types of areas, whereby its presence depends heavily on topography, climate conditions and subsoil properties. Permafrost is almost always to be found above the tree line outside of shady forest areas. Permafrost accounts for approximately 4%-6% of the total land area of Switzerland. The calculated distribution of permafrost shown on the map here takes into account the factors of elevation, slope exposure and terrain. These factors determine whether permafrost will form in loose material, with ice content ranging from low to very high, or in bedrock with ice-filled joints. Ground ice can form when ground water freezes or when water from melted snow refreezes. In some cases, it can result from the remains of an avalanche or small glaciers.

Because of its heavy dependence on temperature conditions, permafrost reacts very sensitively to climate changes. Construction projects in high-mountain regions therefore need to take permafrost factors into account as early as the design stage. Permafrost itself is not considered a natural hazard, but temperature changes in permafrost areas can influence the frequency and intensity of mudslides and landslides, rock slides, avalanches, etc.

Data basis
The modelling of the potential distribution of permafrost in 2005 was conducted by the Federal Office for the Environment with a 25x25m grid. The grid data were vectorised and straightened (edges rounded) for this map in order to achieve a more natural effect. The underlying data show a probability of occurrence of permafrost of between 1% and 99% for each 25x25m square. For this map, the subdivision was merged into four stages in order to enable a clear categorisation. The map therefore can not be used as a basis for planning construction projects in high-mountain regions but is instead meant to serve as a rough depiction of the situation in the Swiss Alps.