Global assessment of drought risk to expanded urban land from 2020 to 2100

Urban land concentrates populations, buildings, and infrastructure, making cities highly susceptible to climate related risks. Drought is one of the most widespread extreme climate events and is expected to intensify with ongoing climate change. As emphasized by the COP29 theme of Resilient and Healthy Cities, it is crucial to understand how future climate change, worsening drought, and continued urban expansion jointly shape urban drought risk. In this study, we integrate future projections of urban land cover with climate, socioeconomic, and demographic datasets to assess drought risk for global expanded urban land from 2020 to 2100 and to identify the major contributing factors. The results show that drought risk will continue to increase across all future climate change scenarios, with developing countries facing higher levels of drought pressure in the future. The dominant roles of drought, urban expansion, and urban vulnerability vary substantially across scenarios and over time, with urban expansion driving risk under low forcing scenarios and drought becoming dominant under more severe ones. Enhancing urban climate resilience, therefore, requires coordinated efforts across climate mitigation, spatial planning, and socioeconomic development. Climate mitigation remains fundamental for limiting long-term risk, while guiding urban expansion and optimizing land use are especially critical for rapidly growing developing countries. Developed countries should reduce drought risk through sustained emissions reductions, urban renewal, nature-based solutions, and cooperation on water resources. Developing countries, in contrast, need to better manage expansion in high-risk areas and strengthen socioeconomic resilience. Building integrated strategies that combine mitigation, planning, and adaptive capacity is essential for enabling future cities to achieve sustainable and safe development under intensifying climate pressure.