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Understanding the socioeconomic effects of past climate change is valuable for sustainable social development. However, quantitative analyses of the long-term relationships between climate change and human society have been limited by a lack of long-term high-resolution data that indicate socioeconomic processes. Here, based on 1,091 records extracted from 25 books on Chinese history and economic history written by leading contemporary scholars, an economic proxy series for China with decadal resolution is presented that encompasses the period from BC 220 to AD 1910. A method for semantic differential and integrating descriptions with multi-time resolution is developed. The statistical results show that warm and wet periods were associated with above-average economic performance, while cold and dry climatic scenarios greatly increased the possibility of economic crisis. Temperature was more influential than precipitation in explaining the long-term economic fluctuations, whereas precipitation displayed more significant effects on the short-term macro-economic cycle. It is proposed that the climatic effects on agrarian economic development were highly dependent on the social vulnerability, which is determined by particular social, economic and political backgrounds. From a deep time perspective, our study may provide new insight into the current intense arguments regarding the economic effects of global warming.

Historical case studies of climate change impacts and the resulting social responses can provide analogies for better understanding the impacts of current and future climate changes. Around the turn of the 19th century, the climate of the North China Plain experienced a shift from a relatively warm stage in the 18th century to a colder stage in the 19th century, which was characterised by a much colder climate and more frequent and severe floods and droughts. Historical information about refugees, social disorder, grain transportation, and disaster relief on the North China Plain in 1780–1819 is collected from the Veritable Records of the Qing Dynasty (a collection of official records). The mechanism of climate change affecting the food security of the society, as indicated by the development of a refugee problem around the turn of the 19th century, is analyzed by examining the social vulnerability. There are four basic findings: (1) In the 40 years from 1780–1819, the society on the North China Plain was unstable and characterised by a significant deterioration of the refugee situation. The number of refugees increased markedly, and their behaviour became increasingly violent. In the 1780s, most of the disaster victims chose to stay at their residences waiting for relief. From 1790 to 1800, hundreds of thousands of refugees migrated to northeast China. In the 1810s, the frequency of farmer rebellions increased sharply. (2) The increase in instability corresponded to the climatic cooling over the same time period. The increased instability was a result of the negative impacts of climate change accumulating and transmitting to the social level. (3) For food security, a precondition for the negative impacts of climate change on human society was the vulnerability of the regional socioeconomic system, which had a high sensitivity and low capacity to respond. This vulnerability could be described by the following three observations: ① The regional balance of supply and demand for food was in a critical state, which led to a high sensitivity and dramatic reduction in yield that was caused by climate change; ② the capacity for disaster relief efforts by the government was too low to meet the needs of crisis management; ③ the capacity for refugees’ resettlement in eastern Inner Mongolia and northeast China, which both border the North China Plain, was severely restricted by climatic conditions or the quarantine policy. (4) It is estimated that climate change caused the social vulnerability to reach a critical level approximately 20 years earlier on the North China Plain.