This project aims at better understanding the impact of the climate change on the morphologic and environmental processes in the Mont-Blanc Massif (MBM), with particular focus on the reduction of glacier surface-area, rock-fall increase related to permafrost warming and downstream changes of water and sediments fluxes. Adequately tackling the environmental and societal challenges arising from the acceleration of these processes requires 1) a documentation of the spatio-temporal evolution of each component, i.e. local climate, rock faces, glaciers, sediment production and hydrological regimes; and 2) an understanding of the complex interactions between these components. To address the two issues, we formed a team of climatologists, geomorphologists, glaciologists, permafrost specialists and hydrologists that will perform a systemic approach within five work-packages. The first one is dedicated to the coordination aspects; the other four focus on the study of the spatio-temporal changes of the different components influencing the evolution of the MBM: climate, hydrology, permafrost, erosion products, and present-day and Holocene glacier dynamics. In order to investigate the complex interplay between these parameters, active exchange between work-packages will assure cross-analysis of the resulting data. The project is based on both observations (field measurements, remote sensing and geochemistry) and modeling. Direct field observations will benefit from: 1) the contributions of the GLACIOCLIM observatory (LGGE-LTHE) regarding the glacio-hydrological processes; 2) the expertise of the EDYTEM lab in permafrost studies, and 3) the one of the ISTerre lab in erosional processes. Climate modeling will be handled by the “Centre de Recherche de Climatologie” of BioGeoscience. Remote sensing will benefit from the expertise of the LISTIC in satellite image processing while the study of long-term glacial and peri-glacial processes will be based on cosmogenic nuclides, including notably the new in-situ produced 14C dating tool currently implemented at CEREGE. Several modeling will be applied for the present-day (last ~50 years) period: the 1979-today regional climate variability around the MBM will first be analyzed through kilometer-scale numerical climate modeling and compared with statistically downscaled fields derived from atmospheric re-analyses and general circulation models. In addition to climate analysis (mostly focused on local orographic effects), the derived high-resolution data will be used to feed hydrological, permafrost and glacier models. Glacio-hydrological model will rely on a degree-day modeling. Glacier modeling will be based on functions linking mass balance and surface elevation changes, thermal evolution of the permafrost on physical modeling of rock surface temperature distribution, and sub-glacial erosion will be estimated as a function of the basal-ice velocity. Glacier fluctuations, including glacier retreat during the warm periods of the Holocene, will be studied using in-situ produced cosmogenic nuclides (14C and 10Be). An erosion/ice cover history will be deduced from modeled glacier mass balance and sub-glacial erosion functions will be calibrated with the present-day period and forced by different Holocene climate scenarii. Projections of future environmental evolutions will be achieved through a statistical downscaling of climate change simulations using the most recent IPCC scenarii. The reliability of the regionalized climate will be evaluated through comprehensive comparisons with observations under present conditions before applying the downscaling technique to a multi-model, multi-scenario (RCP2.6 and 8.5 radiative forcings) ensemble of global climate models throughout the 21st century. Projection of the glacier extents and permafrost changes till at least the mid-21st century will be statistically deduced from the multi-scenario climatic ensemble applied to the mass balance and thermal models.