Building Footprint Has a Stronger Land Surface Temperature Signal than Building Height across Global Cities

Urban heat is a growing environmental challenge as cities expand and densify. The thermal meaning of added built volume depends on whether volume is produced through larger building footprint, greater building height, or both. Using 2020 hottest-month land surface temperature (LST) and global building data on a common 1 km grid for 1,480 cities, we quantified within-city spatial associations between LST anomalies and building-volume density. We defined the corresponding coefficient as the building volume response (BVR). We separated BVR into the footprint pathway response (BVR-F) and height pathway response (BVR-H). Across these cities, the median BVR was 4.6 × 10-3 °C per 1% difference in building-volume density, and BVR was estimated to be positive in 1,107 cities (74.8%). Median BVR-F and BVR-H were 5.1 × 10-3 °C and 1.3 × 10-3 °C. Under the prespecified near-equal band of ± 0.01 °C on the common 10% scale, 917 cities, or 62.0%, had a larger footprint response. The pathway contrast varied with vegetation structure, surface replacement, land cover, and climate context. These results provide a global basis for interpreting urban densification through land occupation and vertical stacking and for identifying surface contexts where footprint oriented growth is more closely associated with hotter urban land surfaces.