Early disaster response to extreme heat in modern Shanghai, 1873–1949: limited preparedness and unequal protection

As extreme heat has become one of the most deadly climate risks in cities today, a fundamental question is rarely asked: where does a city’s heat-disaster response capacity actually come from? Taking Shanghai from 1873 to 1949 as a case study, this study reconstructs summer extreme heat events by integrating Xujiahui Observatory temperature observations with modern newspapers and municipal archives. Focusing on three representative years (1894, 1934, and 1942), this study compares how heat shocks were transformed into social impacts and governance responses under different institutional contexts. The findings show that the early heat response in modern Shanghai did not arise from a mature policy system, but was rather a patchwork of limited preparedness cobbled together from existing channels of public communication, public health, municipal coordination, social relief, and administrative control. More importantly, this seemingly evolving response system was consistently accompanied by deep-seated unequal protection. Different social groups and urban districts faced vastly different levels of risk exposure and access to relief in the face of heatwaves. There was no linear relationship between heat intensity and social impact; governance interventions could buffer risk in some contexts, but unequal protection remained the norm. Limited preparedness and unequal protection, therefore, constituted the central features of early heat-disaster response in modern Shanghai. The historical experience uncovered in this study reminds us that the legacy of heat-disaster response is not merely a story of technological evolution, but also a long-term challenge concerning equity and governance capacity.