Targeting green space accessibility gaps to mitigate urban heat island risk in rapidly urbanizing megacities

This study integrates urban heat island (UHI) risk assessment with green space accessibility analysis to locate mismatches between heat risk mitigation need and green provision, and identifies the most vulnerable populations. Using Chengdu, China as a case study, we found that UHI risk in Chengdu over the past two decades followed a non-linear trajectory, driven by the evolving and compounding dynamics of surface urban heat island (SUHI) intensity, population exposure, and vulnerability, with population aging significantly contributing to increased risk.

While average green accessibility increased by ∼60% (from 0.32 to 0.51) and inequality declined (population-weighted Gini index decreased from 0.46 to 0.13), green space accessibility gap areas expanded from 173.81 km² in 2000 to 704.28 km² in 2020, concentrating in newly urbanized districts where greening lagged behind expansion. Our findings underscore the importance of prioritizing aging populations and areas with the greatest green space accessibility gaps in socially equitable urban green planning, in order to effectively mitigate UHI risk.