The spatio-temporal evolution of the Chongzhen drought (1627-1644) in China and its impact on famine

Investigations of past extreme climate events offer insights into the interactions between natural forces, ecosystems, and human societies. The Chongzhen drought, which occurred from 1627 to 1644 CE, stands as possibly the most severe drought in central and eastern China over the last 1500 years, remarkable for its duration and extent and the vast number of people affected. Concurrently, a widespread famine emerged, triggering peasant uprisings that are argued as having contributed to the Ming Dynasty's downfall. This study extracted 1802 drought records and 1977 famine records from Chinese historical documents to reconstruct the spatio-temporal progression of the drought and its impact on famine. The records provided drought information of season, duration, and intensity, which enabled a classification of four drought severity levels. Then kernel density estimation reconstructed the spatial pattern of drought and the drought kernel density index (DKDI) series in sub-regions. Between 1627 and 1644, the drought affected most of central and eastern China. The severe drought zone was mainly located north of 29 degrees N, shifting from the northwestern region to the northern region and then expanding to the south. The development of drought in different regions was not synchronized. The northwestern region faced the earliest drought outbreak, which eased in the middle period and peaked in 1640. The northern region's DKDI series forms a single-peaked curve, indicating a gradual aggravation of the drought from 1633 to 1640. The Yangtze-Huai region's DKDI series shows a multi-peaked curve, with repeated cycles of worsening and easing drought, peaking in 1641. Furthermore, the reconstruction of the spatio-temporal progression of famine revealed overlapped ranges and similar development trends to that of the drought. The years marking the peak of the famine kernel density index (FKDI) in the northwestern region, northern region, and Yangtze-Huai region coincided with those of the DKDI. Regression analysis identified drought as the primary factor triggering famine, accounting for approximately 67.3 % of its occurrence. In the northern region, the contribution of drought was higher (73.4 %). Series and correlation analyses indicate a continuity in drought's impacts on famine. This paper further clarifies the dominant pathway of climate impact transmission in this case: extreme drought -> declining agricultural harvest -> food shortage -> famine. Other natural and socio-economic factors, such as locust infestations, nomadic invasions, and economic decline, also played a role in the occurrence of famine. Human response measures were instrumental in regulating the transmission of climate change impacts.