Switzerland's permafrost keeps melting away
Unusually warm temperatures and a lack of snow have taken a toll on permafrost regions in Switzerland. The 12-month period from October 2022 to September 2023 saw some of the highest temperatures on record, with readings 1.5 to 1.9 degrees above average. This marks the warmest year since the weather records began in 1864.
Permafrost, referring to subsurface materials such as rock or gravel that remain frozen for several years, is experiencing retreat in many parts of the country. The Swiss Academy of Sciences in Bern highlights these worrying conditions, as Switzerland deals with extremely warm year after year. In light of these circumstances, it's worth noting that the country has seen an unusually warm October since 2022. Additionally, the winter set in late in high-altitude regions, adding to the lack of snow this season in comparison to previous years.
Usually, observations regarding permafrost take into account the "hydrological" year, which runs from October to September of the following year. This is because assessing precipitation levels is better with a complete year's worth of measurements. From October to the following winter, rain and snowfall typically result in meltwater flowing off during the next year. As of now, there's still no balance for the current hydrological year extending into September 2024, but it's clear that the thaw depth in Swiss permafrost zones hit record highs or came close to them in summer 2023.
Notable increases in thaw depth occur at specific locations. For example, Schilthorn in the Bernese Alps registered a thaw depth of approximately three times the level observed before 20 years ago, with a thaw depth of over 13 meters in 2023. Also, permafrost thawed to greater depths at locations like the Schafberg block glacier above Pontresina, reaching several decimeters, while at the Stockhorn above Zermatt, the thaw depth increased by a staggering two meters.
Oddly enough, a lack of snow cover in the early winter can actually benefit permafrost. As Jeannette Nötzli from the Institute for Snow and Avalanche Research in Davos put it to the German Press Agency, a lack of snow cover at the start of winter makes it easier for the ground to cool down. This was quite evident during the fall of 2023, when early snowfall in high-altitude areas stored heat in the ground. The result? Very high winter temperatures in the top layers that were then transported to deeper levels in the ensuing months.
