Biophysical impacts of urbanization on climate change and vegetation in Borneo island

Urbanization causes compounding adverse impacts with climate change on regional ecology and society through biogeophysical processes. Borneo Island of Indonesia has been undergoing rapid urbanization under climate change, but the compounding impact of urbanization remains unknown. Here, we investigate how idealized urbanization affects regional climate and vegetation using Community Earth System Model version 2 (CESM2) simulations with two land cover scenarios for Borneo: 1) a control scenario and 2) an urbanization scenario for the 2025–2034 period. Results show that urbanization in Borneo alters surface biophysical properties, imbalancing the regional surface water budget and thus leading to a warmer (+0.25°C) and drier (−0.17 mm/day) climate across the island, with particularly pronounced effects on the dry period climate. Furthermore, these urbanization-induced climate responses contribute to additional vegetation loss. Moreover, vegetation in Kalimantan, the site of Indonesia’s new capital, is particularly sensitive to the combined impact of urbanization with climate changes. This study highlights the importance of considering biophysical climate effects when assessing the compounding impact of urbanization, which guides policy makers in updating current climate adaptation plans for sustainable urban development.