Variations in Surface Urban Heat Island and Urban Cool Island Intensity: A Review Across Major Climate Zones

The climate has an impact on the urban thermal environment, and the magnitude of the surface urban heat island (SUHI) and urban cool island (UCI) vary across the world’s climatic zones. This literature review investigated: 1) the variations in the SUHI and UCI intensity under different climatic backgrounds, and 2) the effect of vegetation types, landscape composition, urban configuration, and water bodies on the SUHI. The SUHI had a higher intensity in tropical (Af (tropical rainy climate, Köppen climate classification), Am (tropical monsoon climate), subtropical (Cfa, subtropical humid climate), and humid continental (Dwa, semi-humid and semi-arid monsoon climate)) climate zones. The magnitude of the UCI was low compared to the SUHI across the climate zones. The cool and dry Mediterranean (Cfb, temperate marine climate; Csb, temperate mediterranean climate; Cfa) and tropical climate (Af) areas had a higher cooling intensity. For cities with a desert climate (BWh, tropical desert climate), a reverse pattern was found. The difference in the SUHI in the night-time was greater than in the daytime for most cities across the climate zones. The extent of green space cooling was related to city size, the adjacent impervious surface, and the local climate. Additionally, the composition of urban landscape elements was more significant than their configuration for sustaining the urban thermal environment. Finally, we identified future research gaps for possible solutions in the context of sustainable urbanization in different climate zones.