Urban green and blue infrastructure and microclimate regulation: a systematic review of urban heat island and urban planning strategies

Urbanization has exacerbated urban heat island (UHI) effects, posing challenges to thermal comfort, energy efficiency, and urban resilience. Urban green and blue infrastructure (UGBI) offers effective cooling solutions; however, their performance varies significantly across urban morphology, climate zones, and local contexts. This review synthesized 203 empirical studies conducted in 102 cities across 43 countries and 23 Köppen climate zones, offering a comprehensive evaluation of UGBI cooling intensity, spatial reach, and influencing factors. We provide three key recommendations to enhance climate adaptation: (1)establish a standardized evaluation framework for UGBI cooling effects, integrating data collection, modeling approaches, and indicator systems to enhance cross-study comparability; (2)analyze variability in UGBI performance across diverse climatic and urban contexts, highlighting how factors such as vegetation density, urban geometry, and socioeconomic constraints influence cooling intensity and attenuation; (3) explore synergistic interactions between UGBI, urban morphology, and innovative materials, proposing integrated strategies for sustainable urban planning. By bridging critical gaps in cross-climatic comparisons and offering actionable insights, this review provided practical guidance for enhancing urban resilience to climate change.