Correlation between climate and grain harvest fluctuations and the dynastic transitions and prosperity in China over the past two millennia

The social impacts of climate change constitute an important field within the study of global change. The impacts of historical climate change on dynastic transitions and prosperity in China from a food safety perspective is a helpful research topic that contributes to a better understanding of the impacts, process, and mechanism of climate change, as well as a reference for projecting the impacts of climate change in the future. This study defined the periods of dynastic transitions and prosperity in China from 210 BC to AD 1910 and analyzed the relationships among dynastic transition or dynastic prosperity, climate change, and grain harvests. From 210 BC to AD 1910, dynastic transitions mostly coincided with cold ages or the periods that changed from warm to cold and dry or wet-to-dry periods when there was relatively poor harvest. In contrast, dynastic prosperity mostly coincided with warm ages or the periods that changed from cold to warm and wet or dry-to-wet periods when there was relatively bumper harvest. Meanwhile, the dynastic transitions from a divisive dynasty to a unified dynasty often came with a progressively warm phase on the century scale when grain harvests increased. Interestingly, the division of a unified dynasty often came with a progressively cold phase and poor harvests. Furthermore, changes in temperature and agricultural production may be one of the most important factors leading to the collapse of Tang Dynasty. In conclusion, the fluctuation of grain harvests and climate change correspond with the transitions between a tumultuous society and an ordered one, which reveals that the social sensitivity periods were often a result of a change to a colder climate on the century scale.