HR: 10:40h
AN: C22A-02 INVITED     [Abstracts]
TI: Impacts of Climate Change on Permafrost in Mid-Latitude Mountain Regions
AU: * Frauenfelder, R
EM: regula.frauenfelder@geo.unizh.ch
AF: Department of Geography, University of Zurich, Winterthurerstrasse 190, Zurich, 8057 Switzerland
AU: Kaeaeb, A
EM: andreas.kaab@geo.uio.no
AF: Department of Geosciences, University of Oslo, Postbox 1047 Blindern, Oslo, 0316 Norway
AU: Roer, I
EM: I.Roer@giub.uni-bonn.de
AF: Department of Geography, University of Bonn, Meckenheimer Allee 166, Bonn, 53115 Germany
AU: Gruber, S
EM: stgruber@geo.unizh.ch
AF: Department of Geography, University of Zurich, Winterthurerstrasse 190, Zurich, 8057 Switzerland
AU: Noetzli, J
EM: jnoetzli@geo.unizh.ch
AF: Department of Geography, University of Zurich, Winterthurerstrasse 190, Zurich, 8057 Switzerland
AB: Global Climate Models (GCMs) predict significant warming through the 21st Century, with the amplitude of change generally increasing at higher latitudes and higher altitudes. Periglacial permafrost in the European mountains occupies today an area about twice as large as the glacierized area. In order to be able to anticipate and quantify the possible impact of forecast climatic change, it is important to investigate and understand the current conditions and dominant processes in these periglacial areas. In this presentation, we review latest findings about the impact of atmospheric warming in mid-latitude mountain regions, focussing on impacts on creeping debris-ice bodies (i.e. rockglaciers) and on the stability of steep rock faces. In debris covered areas, the reaction to warming temperatures is filtered and occurs through the increase in active layer thickness and melting at the top of the permafrost over periods of years. A warming of the temperature profile within permafrost occurs over the span of decades to centuries. Upward displacement of the base of permafrost to reach a new equilibrium thickness takes centuries to millennia. Spatial modelling of the distribution of permafrost suggest a rise of the lower limit of discontinuous Alpine permafrost of around 100 m during the last 150 years. Borehole measurements show a warming of the permafrost in the upper tens of meters of up to 0.5-0.8°C during recent decades. Rising of the permafrost limit leads to climatic inactivation of creeping bodies presently below the lower limit of permafrost. Warming of the permafrost temperature seems to increase creep rates of active rockglaciers. In comparison with debris-covered slopes, rock faces react quickly to climate change. This is due to the absence of a blocky layer and corresponding direct coupling of surface and sub-surface conditions, combined with a low water content and a small transfer of latent heat during melt. Rising temperatures or the complete thaw of permafrost in rock walls can affect their stability. Slopes that are stable when several degrees below freezing or when ice free could be destabilized in the temperature range close to zero. This enhances the risk of intensified rockfall activity and debris flows that threaten infrastructure, cultivated land and inhabited places.
DE: 0702 Permafrost (0475)
DE: 0722 Rock glaciers
DE: 1621 Cryospheric change (0776)
DE: 1630 Impacts of global change (1225)
SC: Cryosphere [C]
MN: Fall Meeting 2005