Patterns and contradictions in the environmental history of Northern China in different periods

Background. Northern China’s environmental history has been shaped by cycles of drought, flood, and famine, yet past studies often relied on single sources—either natural proxies or historical records—leaving contradictions unresolved. Objectives. This study develops a multi-proxy framework to reassess Qing-era hydroclimatic stress by integrating tree-ring precipitation reconstructions, documentary drought reports, and regional PDSI data. We aim to measure both coherence and divergence among proxies and to link these signals to known historical crises. Methods. Proxies were standardized into z-scores and combined into a composite Environmental Stress Index (ESI) through averaging and principal component analysis. A novel Contradiction Index (CI) was introduced to quantify divergence across sources. Statistical analyses included correlation and lag tests, change-point detection, and rolling-window correlations to capture structural shifts in climate–society dynamics. Results. Proxies broadly aligned in detecting major droughts, particularly the 1876–1878 Great North China Famine , but annual correlations were modest. Impacts were largely contemporaneous , reflecting agricultural vulnerability to monsoon failures. Change-points in the early and late 19th centuries marked rising baseline stress and weakening resilience. Rolling correlations revealed stronger climate–famine coupling in the 19th century than in the High Qing. High CI years, such as 1877 and 1910, exposed contradictions that signaled localized impacts and governance failures. Conclusions. Northern China’s crises arose not from climate variability alone, but from the intersection of extreme drought and fragile social systems. The ESI and CI offer new tools for integrating proxies and identifying both coherence and contradiction in climate history.