Quantitative Analysis of Climate Change and Human Crises in History

Abstract

The association between climate change and human crises in history was conceived a century ago. Yet, it remained controversial and even questioned in academia for some time because it was usually substantiated with selective historical cases and verified by qualitative methods. The causal mechanism of the climate-crisis connection was rarely explored. Breakthrough did not occur until high resolution paleo-climate reconstructions become available in recent years. Based on high resolution paleo-climate reconstructions and fine-grained historical socio-economic datasets, we adopted a pioneering approach to examining quantitatively the climate-crisis relationship in pre-industrial societies. Our research findings demonstrated scientifically the association between climate change and various human crises (i.e., population checks, population collapses, and socio-political chaos) in China, Europe, and other countries/regions in the Northern Hemisphere in the pre-industrial era. Furthermore, we worked out a set of causal linkages showing how climate change is eventually translated into human crises. Those linkages were validated by statistical methods. Our results concluded that deteriorating climate, which led to reduced land carrying capacity, was the ultimate cause of human crises in pre-industrial societies. This challenges the Malthusian explanation for human misery. Our studies start a new page in climate change research. With the increasing availability and precision of paleo-climate reconstructions, the application of more sophisticated methods in the climate-crisis research is going to be facilitated. Hopefully, the role played by climate change in human history can be fully unveiled in the near future.