Severe weather disasters to epidemics in China during low and high solar activities from 1 to 1911 Common Era

Historical records truthfully document human life and activities associated with climate and environmental changes. Based on the official historical records for the years 1–1911 Common Era (i.e., a period of 1911 years), we examine how the 408 epidemic events, occurring in 282 years, are related to solar activity, geographical locations, seasons, and natural disasters of anomalous temperature and irregular precipitation, in China. The epidemics occur more frequently during the low solar activity period. The inland area and area north to the climate boundary of Qinling–Huaihe Line along 35° geographic latitude, in particular, suffer epidemics more often during low solar activity periods. In fact, 45% or more epidemics occurred in summer, while less than 9% occurred in winter. The infection is highly related to social distancing, and therefore the epidemics also occur likely in areas with high-density population or heavy traffic. Statistical tests further demonstrate that natural disasters owing to anomalous temperature and irregular precipitation act as mediators which significantly cause the epidemics in ancient China.