[en] Simulation results from two global atmospheric tracer/climate models in the interior of the two major ice sheets at high northern and southern latitudes are presented and discussed. The models are based on two existing general circulation models (GCMs) of the atmosphere, complemented with tracer formulations (sources, transport, mixing, deposition, etc.). The seasonal and shorter term variability of desert dust, sea salt, ²²²Rn, ²¹⁰Pb, and ⁷Be has been studied at the South Pole in Antarctica and at Summit in Greenland. This choice of tracers and test regions serves to focus on the interactions between atmospheric parameters (e.g. the strong and durable surface inversions characteristic of the ice sheets) and tracers, and to limit other influences such as source variability and chemistry. Comparison with available observations is not consistently favorable. Short-term variability in the atmosphere (²²²Rn and ²¹⁰Pb) appears qualitatively reasonable. Seasonal cycles are in some instances opposite to those observed, and mean deposition is clearly too high. The coarseness of model resolution at the high latitudes and the difficulty of setting up efficient formulations for microphysical tracer processes (e.g. dry and wet deposition) are major sources of problems. If these obstacles are overcome, the combined tracer/climate modelling approach can offer quantitative interpretation of the observed features of atmospheric contaminants, or sensitive tests of GCM simulated atmospheric circulation

[en] A first report proposes an overview of the situation and perspectives related to climate change in the Provence-Alpes-Cote-d'Azur region. Based on various publications, it comments climate predictions for this region, proposes an overview of the situation of the water resource and of its necessary protection, describes various disturbances of the environments, effects of climate change on economic sectors and productive areas, and more particularly on town planning and building, discusses the objectives of an energy transition, and also health risks related to climate change. The second report presents some characteristics of the Mediterranean climate and stakes related to climate change (notion of climate-related risks). It proposes an overview of the past and present regional climate (main evolutions of the past climate, refined knowledge of the present climate with instruments and techniques of data spatialization), and proposes prospective elements (understanding of emission scenarios, climate trends for the region, first indicators for four towns of the region, examples of recent thematic studies). The third report proposes a focus on the situation of the regional agriculture in front of climate change (phenology of sustainable plants, risks and opportunities for agriculture, wheat cultivation, innovative practices to improve the sustainability of agricultural systems, scenarios to anticipate the adaptation of Camargue rice production systems, a multidisciplinary initiative for a better assessment of stakes of climate change in mountain pastures), and a discussion of the new constraint on the Mediterranean forest due to climate change (operation of Mediterranean forest systems, adaptive forestry, impact of climate change on forest health and fire risk, the difficult interpretation of signs of climate change in coastal forests, the future of mountain forests, and the impact of ozone on the Mediterranean forest).