Evaluating trends, profits, and risks of global cities in recent urban expansion for advancing sustainable development

In recent decades, the world has witnessed a remarkable surge in urban expansion, leading to profound consequences for the global climate, biodiversity, and ecological environment. Despite the existence of numerous case studies, assessing the precise contributions of individual cities to this global trend has proven challenging, primarily due to the daunting task of collecting census data for thousands of cities. The study conducted a comprehensive analysis of the recent urban expansion in more than 6000 cities, utilizing state-of-the-art long-term datasets of urban impervious surface area (ISA), population, gross domestic product (GDP) data, and a global city boundary. By tracking the changes in ISA, population, and GDP, we assessed the magnitude and direction (increasing or decreasing) of these variables over time at both the global level and across different regions and countries. Through correlation analysis, we established statistical relationships between urban expansion and GDP growth as well as population change. Furthermore, we examined the profits of these cities and evaluated the projected flood risks they faced. Through the study, we conducted a comprehensive analysis and revealed detailed characteristics, patterns, and disparities in city development, economic output, population density, as well as the profits and projected flood risks across cities, countries, and regions. This in-depth understanding of recent urban expansion provides valuable insights for decision-makers and stakeholders to actively promote sustainable urban development and effectively manage associated risks in diverse geographical contexts.