Projections of urban climate in the 2050s in a fast‐growing city in Southeast Asia: The greater Ho Chi Minh City metropolitan area, Vietnam

Abstract

Future urban climates will be influenced by both global climate change and localized urbanization, especially in fast‐growing cities. This study provides regional climate projections for the 2050s for greater Ho Chi Minh (HCM) City, a fast‐growing megacity in Southeast Asia. These projections are generated through dynamical downscaling of three different Coupled Model Intercomparison Project Phase 5 (CMIP5) global climate models driven with two different representative concentration pathway (RCP) emission scenarios. Furthermore, this study numerically evaluates the impacts of future urbanization and global climate change on the thermal environment of this city. The Weather Research and Forecasting (WRF) model is used to produce these projections, having first been updated with current and future (master plan‐based) land use data with a horizontal resolution of 1 km. The results show that, in rural areas, the spatially averaged monthly mean air temperature in April is projected to increase by 1.2 and 1.7 °C by the 2050s under the RCP4.5 and RCP8.5 scenarios, respectively. In newly urbanized areas, an additional warming of 0.5 °C is expected under both scenarios, which corresponds to 20–30% of the global warming. In particular, the additional warming due to urbanization can exceed 0.8 °C at night. The impact of future urbanization (0.5 °C) is comparable to the difference in the temperature increases achieved under the different RCP scenarios. Thus, this impact should be considered in studies of the future urban climates of fast‐growing cities in developing countries.