Assessing the cooling potential of green and blue infrastructure from twelve US cities with contrasting climate conditions

Abstract

Rapid urbanization, coupled with climate change, has intensified the need for effective urban heat mitigation strategies. Urban green and blue infrastructure (UGBI), including green spaces and water bodies, plays a key role in mitigating the urban heat island effect and promoting urban resilience. This study analyzed 4617 urban green spaces (UGS) across twelve U.S. cities, representing a range of Köppen climate zones, to explore the structural and functional attributes that contribute to urban cooling. Using GIS and Generalized Linear Mixed Models (GLMM), we examined the interactions between UGS and blue spaces to better understand their combined effect on local temperature regulation. Our findings underscore the importance of vegetation density, proximity to water, and park size in reducing land surface temperature (LST), with average LST reductions of up to 3 °C in parks with denser vegetation. Greener parks, located near water bodies, were strongly associated with cooler temperatures, emphasizing the synergistic cooling effect of UGBI. Larger parks, particularly those around 350 ha, were more effective at reducing LST. Interestingly, taller buildings adjacent to UGS showed a slight increase in LST until a height of approximately 20 m, after which the effect plateaued. Proximity to water showed a strong cooling effect within 4 kilometers, beyond which the effect diminished and eventually reversed. These findings provide actionable insights for urban planners and policymakers, illustrating how strategic UGBI interventions—especially in cities with high-density urban forms—could reduce local temperatures, mitigate heat-related risks, and enhance urban resilience to climate change.