Seasonal and Regional Heterogeneity of Volcanic Impacts on Climate and Society in East Asia (1368–1912)

This study investigates how volcanic eruptions influence climate anomalies and climate-related societal stress in East Asia during 1368–1912(Ming and Qing Dynasty). Volcanic eruptions can loft sulfate aerosols into the stratosphere, reduce incoming solar radiation, cool the surface, and disrupt circulation and monsoon moisture transport; in agrarian economies, these shocks may propagate into harvest shortfalls, food-price spikes, famine, and political instability. We define eruption event years (t0) using an ice-core sulfate–based volcanic chronology. We use temperature and precipitation indices from the REACHES (Reconstructing East Asian Climate Historical Encoded Series, REACHES) database, which converts qualitative weather descriptions preserved in Chinese historical archives (e.g., local gazetteers, memorials, and official reports) into standardized, quantatative indices. We apply Superposed Epoch Analysis (SEA) to estimate mean anomalies within a t0±K-year window around eruptions, and we stratify results by season and sub-region to resolve when and where impacts are strongest. Results indicate that cooling is detectable but not spatially uniform: the magnitude, persistence, and timing of post-eruption cooling vary across regions and between warm- and cold-season windows, implying seasonally modulated pathways of volcanic forcing. Precipitation responses are more heterogeneous, showing regionally specific shifts and lags consistent with differing monsoon sensitivities. Building on these climate anomalies as a background stressor, we compile and align socio-economic indicators—grain-price fluctuations, famine reports, and records of social unrest—to assess whether post-eruption societal risks are amplified under particular seasonal–regional configurations. We further examine governmental responses to mounting pressures, including relief provisioning, granary operations, and price-management practices. By integrating documentary climate indices with historical socio-economic evidence, this study provides support and a historical interpretive framework for the eruption–regional climate response–societal vulnerability nexus.