One of the joint issues in archaeology and paleoenvironment is the impact of climate changes on human populations and their means of adaptation. Determining the impact of climatic changes on past human populations is difficult and needs to identify possible synchronicities between a climatic event and a cultural transition. However, the identification of a concomitance is undermined by the uncertainties inherent in the chronologies of archaeological sites (dating methods) and by the resolution of environmental data. Our study focuses on improving the temporal resolution of these environmental data for southwestern France, a region that has provided abundant studies on cultural traditions since the Middle Palaeolithic. Pollen grains and spores preserved in marine sediments are good tracers of environmental changes and our study was carried out using a deep-sea core collected in the Bay of Biscay. This analysis made it possible to study at very high-resolution (100-300 years), the environmental changes in southwestern France between 44,000 and 35,000 years before the present. We then compare our results with the chronology of cultural transitions in the southwestern France, allowing us to better understand whether climate changes may have been concomitants with the development of these cultural transitions. Our very high-resolution pollen study and other climate tracers preserved in the same samples allowed us to detect several climate phases and associate them with the main climate events in the North Atlantic Ocean and Greenland, i.e. Dansgaard-Oeschger cycles and Heinrich events. In addition, we were able to observe three phases during the Heinrich 4 stadial, which were identified in very high-resolution studies of Greenland ice cores, but also in deep-sea cores from the Iberian margin.