Climate change is characterised by changes in mean climate, but also by changes in its shorter term variability. These changes in short-term (from intra-seasonal to interannual) variability are actually one of the aspects of climate change which are better perceived by the general audience and which can have large impacts on the environment. They raise the question of the link between changes in mean climate and changes in the variability around this mean change. The PhD subject we want to develop deals with this topic under the framework of palaeoclimate modelling and the way palaeoclimates are reconstructed from climatic indicators such as pollen or marine sediments. A first aspect of the research to be developed will be to study the modes of extratropical variability in an ensemble of palaeoclimate simulations performed at IPSL, encompassing the Last Glacial Maximum climate as well as the Holocene and, time allowing, the Eemian climates. Then, the impacts on vegetation and marine biogeochemistry will be investigated. A further development will consist in evaluating the response to the vegetation feedback in these different climate contexts.