Climates and human societies over the past two thousand years (continued)

Climatic variations over the last two millennia have had undeniable impacts on human societies. We will examine several emblematic cases that are the subject of major recent research, including the expansion of Viking societies during the medieval climatic optimum, the emergence and decline of the Roman Empire in Europe and the Mediterranean, and the Maya civilization in Mesoamerica. The reconstruction of climate series is based on the analysis of complex geochemical, geophysical and paleobiological parameters, measured in a variety of natural archives (trees, lake and marine sediments, stalagmites, polar ice and mountain glaciers). To complement the expertise developed on these indicators, it is often necessary to model past climates. These approaches, both empirical and numerical, make it possible to assess the links between climatic dynamics and socio-historical trajectories, particularly during phases of expansion, transformation or decline of the societies studied. These analyses thus provide a framework for assessing the sensitivity and resilience of populations to environmental constraints, and help to shed light on our contemporary choices in the face of climate change. However, comparisons should be made with caution, as today's globalized society differs profoundly from those of the past, particularly in terms of demographics and global connectivity.