Paleoclimatology

Keywords: Paléoclimat, archives climatiques, modèles paléoclimatiques, impact climatique sur les groupes humains passés.
Prerequisites: Bases en dynamique du climat mais non nécessaire

The knowledge of past climates at the global and regional scales is a key element for a better understanding of the present climate and for a better projection of its future evolution. The wide range of climates identified over the last few million years has been the result of changes in the different terrestrial boundary conditions (insolation, ice volume, greenhouse gas concentration, palaeogeography) and related feedback phenomena (albedo, oceanic and atmospheric processes, etc.). Past climates have not been affected by anthropogenic impact, but they represent a necessary reference to discriminate what is attributable to anthropogenic influence in the current variability and trend. Furthermore, knowledge of the magnitude, direction and frequency of these past changes is essential to constrain and assess the models used for climate projections of future climate change. This course on past climate change will begin with an introduction including a history of the discipline such as the origin of the theory of glacial ages and that of the astronomical theory of climates as well as the methods used to reconstitute past climates: a) Marine, continental and glacial archives with the study of micropaleontological, geochemical and sedimentological tracers preserved in these archives, (b) dating methods and comparison between archives, (c) the basis of paleoclimate modeling, and (d) model-data comparison. We will also present some examples of past long-term changes (glacial-interglacial cycles), the rapid events of the last climate cycle or the Phanerozoic climates. Finally, we will also discuss the impact of climate change on the evolution of human populations: migrations, expansion …. Practical work will complement this training offer: modelling practical exercises (simple models and complex models) and practical exercises based on data from the marine or continental archives.