Permafrost and periglacial research activities were mainly conducted in several laboratories in France: GEOLAB (UMR 6042, CNRS-Clermont-Ferrand University), THEMA (UMR 6049, CNRS-Franche Comté University), M2C (UMR 6143, Caen University), IDES (UMR 8148, CNRS-Paris-Sud University) and SET (UMR 5603, CNRS-Pau University).
The periglacial group of the University of Caen continues to investigate the effects of climate warming on periglacial slopes. New experiments have been focused on the evolution of erosion processes and the changes in slope morphology, when water supply evolves as expected during climate warming.
The programme Laboratory simulation of solifluction processes associated with one-sided and two-sided active layer freezing from the Cardiff group lead by C. Harris is concluding. It provides new data on solifluction processes and soil behaviour in the presence of permafrost (see also the UK report).
The polar research group of the Laboratory of Physical and Environmental Geography of Clermont-Ferrand was involved in various activities of the periglacial community. Most of the fieldwork was carried out in Iceland, which is the main field area. The scientific collaboration between A. Decaulne and Þ. Sæmundsson, Natural Research Centre of Northwestern Iceland, Sauðárkrókur, continued on periglacial dynamics impact on slopes in northwestern, northcentral and southern Iceland, with specific emphasis on slope processes, slope deposit stratigraphy and dendrogeomorphology, and on the survey of the patchy permafrost and active layer in the Icelandic highlands. A. Decaulne also cooperates with S. Conway, J. Murray and M. Balme, from the Open University, UK, in studying debris-flow landforms in northwestern Iceland, and comparing the morphological properties of these slope landforms with those observed on the Mars surface.
Based on lab analyses by P. Bertran (INRAP-IPGQ, Bordeaux) and J. Arocena (UNBC, Canada), field observations previously carried out by M.-F. André and K. Hall (UNBC, Canada) on the Falklands “stone runs” resulted in the proposal of a new interpretation of these block streams. The different explanations suggested since Darwin, and during the past half-century, provide a good illustration of contemporary shifts in periglacial geomorphology. A more general historical overview of periglacial research, from the Climatic Geomorphology “golden age” to the current Global Change “fever”, was provided by M.-F. André at the joint periglacial meeting of the Geological Society of London and the Quaternary Research Association.
Research is also carried out on a glacier system of Svalbard. The objective of the Hydro-sensor-FLOWS project (IPY no. 16) is to investigate the hydrology of the Austre Lovénbreen glacier basin (Brøgger peninsula, Svalbard) by continuous monitoring in space and time of dynamics over a four-year period (2007-2010). The project is coordinated by M. Griselin (UMR Thema) and C. Marlin (UMR IDES) in association with SET (Pau) and FEMTO (Besançon). The main objective is to improve our understanding of the system response to contemporary climatic fluctuations (40 years). Different methods are used to study the glacier and its hydrology and its dynamics: image loggers (satellites and automatic cameras on the ground), loggers recording meteorological data, air temperature at 30 locations in the basin and hydro-geochemical data. The mapping of the top of permafrost and the base of the glacier by GPR is carried out by AWI scientists. The thinning of the glacier Austre Lovénbreen between 1995 and 2007 is 40 m at the front. An analysis of the meteorological data of the Ny-Ålesund station (1969-2006) compared with the first results obtained with the temperature loggers located on the glacier indicate anomalously warm conditions on the glacier during the beginning of August (average value up to 10 °C), implying a very high rate of melting. During the winter 2006-2007, at least 13 positive “warm” events were observed. This would indicate that melting could occur over the whole glacier surface even during the polar night.
A detailed analysis of the hydrology of the Lena was performed by E. Gautier and D. Brunstein at the Laboratoire de Géographie Physique (Meudon) in cooperation with F. Costard (IDES laboratory, Orsay University), A. Fedorov (Permafrost Institute, Yakutsk) and D. Yang (University of Alaska, Fairbanks). Three major changes since the 1990s has been reported: a reduction of the river ice thickness in winter, a pronounced increase of the water temperatures in spring, and a slight increase of the discharge during the break up (May-June). Recent climatic change in central Siberia and its impact on the fluvial thermal erosion has been reported. A GIS analysis based on aerial photographs and satellite images highlights the impact of the water warming on the frozen banks. The vegetated islands appear to be very sensitive to the water temperature increase, showing an acceleration of their headward retreat (21 to 29 %).
Physical modelling of Martian gullies continues (F. Costard, UMR IDES 8148). Small gullies observed on Mars could be formed by groundwater seepage from underground aquifer, or may result from the melting of near surface ground ice at high obliquity. To test these different hypotheses, a laboratory simulation within a cold room was performed. The experimental slope was designed to simulate debris flows over sand dunes with various slope angles, and different granulometry and permafrost characteristics. Various laboratory simulations bring new constraints on the triggering of Martian flows. Preliminary results suggest that the typical morphology of gullies observed on Mars can best be explained by the formation of linear debris flows related to the melting of the near-surface ground ice within silty materials.
Current research concerning the performances of the WISDOM Radar (Water Ice and Sub-surface Deposit Observation on Mars) on the ExoMars rover mission (European Space Agency) are in progress at the Laboratory IDES (Orsay University) in cooperation with V. Ciarletti (CETP). It concerns various simulations of the radar response to realistic geologic models of the Martian subsurface. The detection of discontinuities with a Ground Penetrating Radar (GPR) prototype is performed in a 0.7 m3 frozen soil in a cold room.
François Costard (firstname.lastname@example.org)