Permafrost (CLIM 011) - Assessment published Nov 2012

Key policy question: What is the trend in the temperature and the thawing depth of permafrost soils across Europe?

Observed permafrost temperatures from selected boreholes in European mountains

Note: The figure shows observed permafrost temperatures from 10 m (left) and 20 m (right) depth and their evolution for selected boreholes in European mountains: the sites of the PACE transect and two additional sites in Switzerland (Matterhorn and M.d. Barba Peider) and one in Norway (Dovrefjell).

Data source:

• Permafrost in the Swiss Alps provided by University of Zurich

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Comparison of active layer thickness from boreholes in the Alps, Norway and Svalbard

Note: The figure shows the comparison of the active layer thickness from boreholes in the Alps, Norway and Svalbard.

Data source:

• Permafrost in the Swiss Alps provided by University of Zurich

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Key assessment

Past trends

Permafrost data is collected through national networks as well as globally. This information shows the regional and seasonal variation as well as trends in permafrost temperatures. Changes in below-ground temperatures can be influenced as much by temporal variations of snow cover as by changes in the near-surface air temperature. It has also become evident that landform characteristics such as elevation, topography, surface cover and soil type also influence the effects of climate change on permafrost.

Data from three boreholes, to a depth of 100 m or more, extending from Svalbard to the Alps indicate a long-term regional warming of permafrost of 0.5–1.0 °C during the recent decade [i]. Continuous monitoring over 5–7 years shows warming down to 60 m depth and current warming rates at the permafrost surface of 0.04–0.07 °C/year, with greatest warming in Svalbard and northern Sweden [ii]. In Switzerland, some warming and increasing active-layer depths (top layer of the soil that thaws during the summer) have been observed [iii], but results vary between borehole locations and site characteristics such as different snow cover, surface cover, subsurface material, ice content in the underground and temperature conditions. (Figure 1)

In Europe data series with a length of more than 15 years are available from Greenland, Svalbard, northern Sweden and Switzerland. Active layer thickness has generally increased during the period of observation, but there is also significant variation due to site characteristics. (Figure 2)

Projections

Permafrost areas are affected by the rate of warming and will very likely continue to thaw across Europe, with the possible exception of Svalbard, where permafrost thaw can mainly be expected at low elevations close to the coast [iv] [v]. Projections have also shown that the palsa mires in Fennoscandia represent a special case of arctic permafrost where rapid responses can be expected. The probability of a complete loss of palsas in northern Fennoscandia during the 21st century is sensitive to the emissions scenarios.

[i] Charles Harris et al., „Permafrost and climate in Europe: Monitoring and modelling thermal, geomorphological and geotechnical responses“, Earth-Science Reviews 92, Nr. 3–4 (Februar 2009): 117–171, doi:10.1016/j.earscirev.2008.12.002.

[ii] Ketil Isaksen et al., „Recent warming of mountain permafrost in Svalbard and Scandinavia“, Journal of Geophysical Research 112 (Februar 8, 2007): F02S04, doi:10.1029/2006JF000522.

[iii] Jeannette Noetzli and Daniel Vonder Muehll, Permafrost in Switzerland 2006/2007 and 2007/2008 Glaciological Report Permafrost (Cryospheric Commission of the Swiss Academy of Sciences, 2010), http://www.institut-montagne.org/ori-oai-search/notice.html?id=institut-montagne-ori-wf-1-76787&format=dc_id.

[iv] Thomas Voigt et al., Impacts of climate change on snow, ice, and permafrost in Europe: Observed trends, future projections, and socioeconomic relevance, ETC/ACC Technical Paper 2010/13 (Copenhagen: European Topic Centre on Air and Climate Change (ETC/ACC), 2010), http://acm.eionet.europa.eu/reports/docs/ETCACC_TP_2010_13_Cryosphere_CC_impacts.pdf.

[v] B. Etzelmüller et al., „Modeling the temperature evolution of Svalbard permafrost during the 20th and 21st century“, The Cryosphere 5, Nr. 1 (helmikuu 2011): 67–79, doi:10.5194/tc-5-67-2011.