Revealing the dynamic effects of land cover change on land surface temperature in global major bay areas

Comparative studies across national boundaries on urban heat islands (UHI) are lacking, especially comparative analyses among globally important bay area urban agglomerations at different levels of urbanizations. Bay areas around the world are currently experiencing different stages of urbanization, and the transformation of urban land cover into thermal environments varies significantly. This study investigated the spatial-temporal changes of land cover change (LCC) and the land surface temperature (LST) in four major bay areas (including the San Francisco Bay Area (SFBA), the New York Bay Area (NYBA), the Tokyo Bay Area (TBA), and the Guangdong-Hong Kong-Macao Bay Area (GBA)) from 2000 to 2020. Utilizing correlation analysis and the multiscale geographical weighted regression model (MGWR), the goal was to understand how LCC impact the thermal environmental regionally. The results showed that: (1) The main shift in land cover involved a decrease in forested and cultivated area and an increase in impervious surfaces, with deforestation and agriculture conversion being major factors in this increase. The GBA gave a significant 112% rise in impervious surface during this period. (2) The LST trended towards higher, medium LST zones, closely linked with urban impervious surface expansion. (3) The MGWR model highlighted the direct non-stationary relationship between land cover alterations and LST effects. It showed that conversion to impervious surfaces, particularly from water and cultivated lands, markedly intensified LST, whereas water bodies and forests demonstrated a substantial capacity to mitigate LST. Urban planners were advised to mitigate LST elevations stemming from the transformation of forest lands and aquatic environments into impervious areas, a change notably prevalent in highly urbanized regions. This study provides valuable perspectives on balancing the management of urban thermal environments and urbanization processes.