Revealing the urban heat exposure risk network: Exploring the possibility of mitigate heat-related risks form a network perspective

The exposure of urban residents to heat waves is expected to increase in the future. However, the analyses regarding the spread characteristics and trends of heat exposure risk in different cities are lacking. In this study, we proposed a framework to identify the network spread characteristics of heat exposure risk based on morphological spatial pattern analysis and applied it to 33 provincial capital cities in China. We explored the patterns and characteristics of heat exposure risk diffusion at different urbanization stages and for different urban sizes and in response to socioeconomic factors. The results show that network spread is common in all cities. From 2000 to 2020, heat exposure risk exhibited a strengthening diffusion trend, and Line to Surface accounted for the highest proportion and area. There are great differences in the degree of heat exposure risk expansion in different cities. Urban size determines the speed of expansion in heat exposure risk, and the proportion of risk areas indicates that some medium-sized cities, such as Haikou and Lanzhou warrant greater research attention. Socioeconomic factors, notably GDP, positively influence risk expansion, but their impact weakens over time and with urban size growth. The present research results provide evidence for the spread characteristics of heat exposure risk, and provide a new perspective for mitigating the heat-related risk.