How urban sprawl patterns shape the thermal environment during hot summers: An empirical analysis of 338 Chinese cities

With accelerating global warming trends, urban sprawl has emerged as a key driver of thermal environment changes in urban areas. However, limited attention has been given to how sprawl patterns shape the thermal environment at the city level. This study sets out to reveal the heterogeneous relationship between the spatial patterns of urban sprawl and thermal environment by analyzing 338 Chinese cities during hot summers from 1990 to 2020. Multi-source data were employed to assess the spatial arrangement and temporal dynamics of four urban sprawl patterns (centering, clustering, fragmentation, and complexity) alongside thermal conditions. A geographically weighted regression model revealed spatially varying associations between sprawl patterns and thermal environment. Results indicate a northward gradient of thermal deterioration, with the most severe warming in Northeast and Northwest China, while some southern tropical cities exhibit localized cooling. Sprawl patterns vary across regions and exhibit dual heterogeneity in their thermal impacts. Fragmentation demonstrates cooling effects in the southeastern coast, eastern Northwest, and northeastern Southwest China. Clustering improves thermal conditions in the southeastern coast, Bohai Rim, and northeastern and northwestern China, but intensifies heat stress in the southwest. Complexity worsens the thermal environment in the Yangtze River Delta and the junction of eastern Northwest and northeastern Southwest China, while slightly mitigating the thermal environment in northern cities. Centering shows limited impact, with minor improvements observed in southeastern coastal cities. Based on these findings, seven optimization zones have been identified with tailored thermal-mitigation strategies, providing evidence to guide regionally adaptive planning for climate-resilient urban development. • Urban thermal environments in China worsen along a latitudinal gradient northward. • Urban sprawl exerts dual heterogeneous impacts on thermal environments in China. • Identified seven optimization zones in China. • Proposed tailored climate-resilient strategies for different zones in China.