Urban Heat Island Intensity and adapted policy in Taiwan

The urban heat island (UHI) effect, exacerbated by climate change, poses a growing challenge to urban living conditions in Taiwan. With its unique topography featuring steep elevation changes—from sea level to 3950 meters within just 140 km—Taiwan requires tailored definitions of urban heat island intensity (UHII) to account for its diverse geographic and climatic characteristics.

This study employs 2-km resolution Taiwan ReAnalysis Downscaling data (TReAD) from the Taiwan Climate Change Projection Information and Adaptation Knowledge Platform (TCCIP) to analyze temperature trends over the past decade. Using geographic information system (GIS) analysis, UHII was calculated by integrating urban climate and topographical features. Low-temperature reference points were carefully selected based on stringent criteria, including their location within a 5-km rural buffer zone, an altitude below 100 meters, and limited mountain coverage (<10%). Cities were classified into basin-type and coastal-type based on their UHII characteristics.

Findings indicate significant variations in UHII by urban typology. Basin-type cities, like Taipei and New Taipei, experience heat accumulation due to enclosed terrain, with summer daytime UHII reaching 1.6°C and nighttime rising to 3°C. Coastal-type cities, such as Tainan, are influenced by land-sea breezes, leading to dynamic UHI patterns; inland areas reach 1.7°C during the day, while coastal regions experience up to 2.5°C at night. Spatial analyses further reveal high-temperature zones concentrated in densely developed or industrial areas.

This research provides a robust framework for understanding UHI under Taiwan’s distinct conditions, offering critical insights to support urban planning and targeted climate adaptation strategies for effective UHI mitigation.