Urban Affairs Review, Ahead of Print.
This paper analyzes case studies of Urban Metabolism (UM), an interdisciplinary field that studies the flow of materials and energy in cities. It focuses on global cases to help researchers identify research gaps. I have categorized the studies based on location, scale, and urban system. Two findings need to be specified: first, the geographic distribution of UM case studies is uneven. Only limited studies have been developed for emerging African cities despite expected large future populations. Second, neighborhood-scale cases do not use an appropriate local scale, primarily due to the lack of reliable data sources. Upon noticing concerns over (1) the evaluation of optimized metabolisms, (2) the effectiveness of knowledge transfer, and (3) the awareness of timeframe in delivering practical policy, researchers may now focus on developing more applicable planning and design guidelines while paying attention to the early communication of UM assessment results between scientists and practitioners.