Tree rings, ice cores and marine sediments, to name just a few sources for paleoclimate research, leave no doubt that climate changed over the past millennia. However, they say very little about the impacts of climate change on human societies over that time. Intuitively and faced with the threats that Global Warming poses to humankind in the 21^st century, we might assume a determining role of climate in the fate of past civilizations. Whether it is the Mayas, the Roman Empire, or the city of Angkor, it seems widely accepted that their rise and fall were linked to beneficial and adverse climate eras. However, we must avoid taking the easy road of environmental determinism. Complex societies never were passive subjects to environmental forces. Moreover, progress in paleoclimate studies over the past decade has fundamentally changed our views on how climate changed over the past millennia, offering nuance to the climate eras that dominated earlier discussions. Paleoclimatology has also shown that current Global Warming is much more extreme than any previous changes in the later Holocene. This lecture seeks to find insights in a comparative approach, arguing that the link between weather, climate, crops food supply, and political stability is not so straightforward. The main conclusion will be that among complex past societies, the long-term impact of climatic changes on population and resources is predominantly determined by and in interaction with societal factors.