'Invisible' Warming: Permafrost Decline

Hi all,

As usual, we're moving around the globe with these posts. So from the circumpolar arctic, back to the Swiss Alps. Today's topic of permafrost decline is obviously connected to cold regions and winter seasons, but not as visibly obviously impacted by climate change. Still, it's important to know of the various effects permafrost decline could have.

Permafrost is permanently frozen soil, which momentarily covers around 6% of the Swiss Alps (Schnee u. Lawinenforschung Schweiz), the majority of which is found at elevations of 2400 m. above sea level. The wording 'frost' implies the involvement of ice, but this is not necessarily the case because the classification of soil as permafrost solely depends on temperature ((Nyenhuis, 2005). The exact definition is disputed, but it is soil of any type that over the course of one year, according to Haeberli (1990) or two years, according to French (2007, first published 1996) has displayed continuous subzero temperatures (Nyenhuis, 2005).

If warming of these regions due to climate change continues, a rapid decline in permafrost cover will be observed in the next decade (Schuur et al., 2008). To correctly predict the development of permafrost cover, there is extensive monitoring in the Alpine countries. In Switzerland alone, data is collected since 1996, at over twenty monitoring stations located between Engadinn, over the Gotthart Area, and Wallis (SLF Permafrost Research Group). This research is lead by the SLF - the Snow and Avalanche Research Center in Switzerland. Their acquisition of correct data is essential to develop numerical models simulating future soil temperature. Since intensive monitoring, interesting patterns have been discovered, e.g. that observed temperature in permafrost, at a depth of at least 10 m. has a typical reaction time of six months. So a particularly warm summer such as the one in 2003 only has an effect the following winter. The yearly variation is very clear in figure 1.

Figure 1. Soil temperatures in several >10 m depth

boreholes in Switzerland, measured on 04.07 between 

1996 and 2008. Source: SLF Permafrost Research Group

So why is it even remotely interesting or important to monitor whether cold soil is staying cold? There are inevitable dangers resulting from the warming of permafrost (Haeberli and Beniston, 1998). "Permafrost degradation in fissured rock walls is likely to have long-term impacts on frost weathering and rock fall activity by reducing the strength and increasing the permeability at depths of meters to tens of meters." (Haeberli and Beniston). Especially when buildings stand on and are secured in a permafrost surface, there is an increased risk of collapse (SLF Research Group Permafrost). This can lead to dangerous situations, which is why research in this area is often passed on to instances responsible for alpine safety. Also, the Snow and Avalanche Research Centre has developed guidelines on permafrost avalanche building and since 2009, also for other types of building development in order to protect tourism and energy security in the Alps.

Finally, this small summary of permafrost shows once again that climate change in seemingly insignificant areas has physical as well as socioeconomic impact. Enjoy the cold in London and elsewhere, and see you here soon!