Processes, spatial patterns, and impacts of the 1743 extreme-heat event in northern China: from the perspective of historical documents

The study of historical extreme heat is helpful for understanding modern heatwaves. By collecting 63 historical documents from three kinds of historical materials and using text analysis methods based on keywords, grading, and classification, this research recovered and analysed the processes of extreme heat over time, the spatial patterns of heat severity, and the impacts of extreme heat in northern China during 1743. The results show the following. (1) The extreme heat of 1743 began to be noticed by people on 22 June; began to kill people on 14 July; and was at its most severe, attracting great attention from the central government, between 14 and 25 July. (2) Extreme heat occurred on the plains of the provinces of Hebei and Shandong and in the valleys of southwestern Shanxi. Areas of the plains east of the Taihang Mountains, such as Baoding, Shijiazhuang, and Xingtai, experienced the worst heat. These areas are also at high risk for heatwaves on the North China Plain in modern times. (3) In 1743, heat affected people, animals, plants, and facilities and had the most severe impact on human deaths. The death toll in a single county reached dozens in a single day. Timely cooling and reducing exposure have been limited but necessary means of addressing extreme heat in both ancient and modern times.