Interplay between aridity changes and urban expansion across Chinese cities

Urban aridification has emerged as a significant challenge to the sustainable development of cities. Although China has experienced rapid urbanization and dryland expansion in recent decades, their relationship and potential challenges remains underexplored. To fill this gap, we conducted a national-scale analysis of spatiotemporal changes in dryland boundaries and urbanization patterns in Chinese cities between 1985 and 2022. Our findings reveal a significant eastward expansion of dryland boundaries beyond the Hu-Huanyong line, increasing the number of cities within dryland regions, particularly large urban agglomerations. Notably, urban growth in dryland areas has outpaced that in more humid regions, especially in cities located in the driest subtypes of these regions. Overall, a significant drying trend has been widely observed in about one-third of Chinese cities, impacting over 100 million people. These findings highlight the increasing vulnerability of urban populations to a drying climate, underscoring the need for climate-adaptive urban policies. Our results contribute to a deeper understanding of the interplay between urbanization and dryland expansion and offer critical insights for developing climate-resilient policies.