Permafrost (CLIM 011) - Assessment published Nov 2012
Climate change (Primary topic)
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
- CLIM 011
Key policy question: What is the trend in the temperature and the thawing depth of permafrost soils across Europe?
- In the past 10–20 years European permafrost has shown a general warming trend, with greatest warming in the cold permafrost in Svalbard and Scandinavia. The depth of seasonal thaw has increased at several European permafrost sites. Some sites show great interannual variability, which reflects the complex interaction between the atmospheric conditions and local snow and ground characteristics.
- Recent projections agree on substantial near-surface permafrost degradation resulting in thaw depth deepening (i.e. permafrost degeneration) over much of the permafrost area.
- Warming and thawing of permafrost is expected to increase the risk of rock falls, debris flows and ground subsidence. Thawing of permafrost also affects biodiversity and can contribute to climate change through release of CO2 and CH4 from arctic permafrost areas.
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).
- Permafrost in the Swiss Alps provided by University of Zurich
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.
- Permafrost in the Swiss Alps provided by University of Zurich
Permafrost data is collected through national networks as well as globally through the Global Terrestrial Network for Permafrost (GTN-P). This information shows regional and seasonal variations as well as longer-term trends in permafrost temperatures. Changes in ground temperatures can be influenced as much by temporal variations of snow cover or surface and subsurface characteristics of the site as by changes in the near-surface air temperature. It has also become evident that the effects of climate change on permafrost depend on factors such as elevation, topography, surface cover and soil type. Partly different processes act between the atmosphere and the ground for bedrock, debris slopes, and rock glaciers.
Data from various boreholes, to a depth of 100 m or more, extending from Svalbard to the Alps indicate a regional warming of permafrost of 0.5–1.0 °C during the recent decade [i] (Figure 1). 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 depth of the active layer (the top layer of the ground that thaws during the summer) have been observed, particularly in the past 5 years, but results vary between borehole locations and site characteristics with different snow cover, surface cover, subsurface material, ice content in the underground and temperature conditions [iii].
In Europe data series with a length of more than 15 years are available from Greenland, Svalbard, northern Sweden and Switzerland. Active layer thickness (i.e. thawing depth) has generally increased during the period of observation, but there is also significant variation due to site characteristics (Figure 2).
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]. Projections for near-surface permafrost degradation continue to vary widely, but virtually all of them indicate substantial near-surface permafrost degradation and thaw depth deepening over much of the permafrost area. Projections based on the ensemble of CMIP5 climate models yield a reduction of near-surface permafrost area (continuous plus discontinuous near-surface permafrost) in the Northern Hemisphere between 37 ± 11% for RCP2.6 and 81±12% for RCP8.5 over the 21st century (Figure 3) [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 scenario [vi].
[i] Charles Harris et al., “Permafrost and Climate in Europe: Monitoring and Modelling Thermal, Geomorphological and Geotechnical Responses,” Earth-Science Reviews 92, no. 3–4 (February 2009): 117–171, doi:10.1016/j.earscirev.2008.12.002; D. G. Vaughan and Josefino C. Comiso, “Observations: Cryosphere (Final Draft Underlying Scientific-Technical Assessment),” in Climate Change 2013: The Physical Science Basis (Intergovernmental Panel on Climate Change (IPCC), 2013), Chapter 4, http://www.climatechange2013.org/images/uploads/WGIAR5_WGI-12Doc2b_FinalDraft_Chapter04.pdf.
[ii] Ketil Isaksen et al., “Recent Warming of Mountain Permafrost in Svalbard and Scandinavia,” Journal of Geophysical Research 112 (February 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; B. Etzelmüller et al., “Modeling the Temperature Evolution of Svalbard Permafrost during the 20th and 21st Century,” The Cryosphere 5, no. 1 (helmikuu 2011): 67–79, doi:10.5194/tc-5-67-2011.
[v] M. Collins and R. Knutti, “Long-Term Climate Change: Projections, Commitments and Irreversibility (Final Draft Underlying Scientific-Technical Assessment),” in Climate Change 2013: The Physical Science Basis (Intergovernmental Panel on Climate Change (IPCC), 2013), Chapter 12; Charles D. Koven, William J. Riley, and Alex Stern, “Analysis of Permafrost Thermal Dynamics and Response to Climate Change in the CMIP5 Earth System Models,” Journal of Climate 26, no. 6 (March 2013): 1877–1900, doi:10.1175/JCLI-D-12-00228.1.
[vi] Voigt et al., Impacts of Climate Change on Snow, Ice, and Permafrost in Europe: Observed Trends, Future Projections, and Socioeconomic Relevance.
Permafrost in the Swiss Alps
provided by University of Zurich
Observed permafrost temperatures in Norway
provided by Norwegian Meteorological Institute
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