Global assessment in the effect of urban built-up environment on cooling efficiency of green spaces

Green space cooling is a nature-based solution to alleviate urban heat risk. However, the relationship between its cooling and urban development, particularly in the context of global economic differences, is poorly understood. Here, we examined the effect of the built-up environment on improving the cooling efficiency of green spaces in 1113 built-up areas. The average cooling efficiency of green spaces in the high-income countries globally is 1.64 times that in the low-income countries. In high-income countries, reducing built-up density and increasing building height can enhance the cooling efficiency of green spaces. Notably, maintaining built-up density below 20% enables relatively high cooling efficiency, regardless of variations in building height. In contrast, in most zones of low-income countries, controlling the low building height tends to achieve better cooling efficiency of green spaces. Our findings provide a scientific basis for optimizing green space layouts tailored to urban climate adaptation across different socio-economic regions. Green space cooling efficiency and its nonlinear links to built-up density and building height vary by income groups, as revealed by an analysis of multiple data from 1113 global built-up areas with generalized additive models.