Evaluating the Benefits of Urban Greenery in UHI Mitigation: Methods, Indicators, and Gaps

Abstract

Urban Heat Island (UHI) effects pose a significant environmental challenge in contemporary urban planning, driven by accelerating climate change, rapid urban development, and changes in land use patterns. This study explores the potential of urban greenery as a mitigation strategy for UHI by conducting a systematic and bibliometric review of 42 peer-reviewed studies, selected using the PRISMA 2020 protocol. A mixed methods approach was employed, integrating qualitative synthesis with quantitative bibliometric mapping using VOSviewer (1.6.19). The findings indicate that urban greenery, including green roofs, street trees, and parks, effectively reduces surface and air temperatures through processes such as evapotranspiration, increased albedo, and shading. Widely used indicators in these studies include Land Surface Temperature, the Normalized Difference Vegetation Index, and canopy coverage. The bibliometric analysis reveals exponential growth in related publications between 2014 and 2024 is R² = 0.8263, along with emerging thematic clusters centered on thermal comfort modeling, nature-based solutions, and urban climate resilience. China, Australia, and the United States account for the majority of contributions, while tropical and lower-income regions remain underrepresented. The study emphasizes the importance of developing standardized evaluation methods, expanding geographic scope, and incorporating socioecological dimensions to support equitable and climate-sensitive implementation of green infrastructure for urban heat mitigation.