Assessing urban surface thermal environment and heat health risk in Chinese cities: A twenty-year study

With global warming and rapid urbanization, urban surface temperatures have risen significantly, challenging residents' health and urban sustainability. Prolonged or frequent high temperature exposure can cause various health issues, making the study of heat-related risks crucial. However, data accessibility issues and other factors limit the temporal and spatial scales of studies. This insufficiently considers intra-urban spatial heterogeneity, hindering detailed exploration of urbanization's impacts on heat risk. Therefore, this paper evaluates the surface thermal environment and heat health risks in Chinese urban areas from 2000 to 2020 using the IPCC's “hazard-vulnerability-exposure” framework. It proposes a method to analyze these patterns at a 100-m resolution among different LCZ types. Results show that heat risks have increased over the past 20 years, with higher risks in the northwest, southeast, and central regions. Built-type LCZs, especially those with high building density and height, have significantly higher heat risks than natural-type LCZs. LCZ 8 and LCZ 10 exhibit relatively high heat risk levels, though lower than dense building zones. In contrast, areas with vegetation (LCZ A-D) and water bodies (LCZ G) show significantly lower heat risks compared to other LCZ types. The paper proposes targeted heat adaptation strategies and planning recommendations based on these findings. • Land surface temperature and heat risk in China rose from 2000 to 2020, expanding outward from urban centers. • Urban heat risks vary across China's various regions, with higher risks in the northwest, southeast, and central areas. • Using LCZ theory allows precise assessment of temperature and heat risk relationships with urban structures. • Heat risk in natural LCZ types is significantly lower than in built-up LCZ areas.