Examining urban metabolism: A material flow perspective on cities and their sustainability
The resource challenge associated with anthropogenic forces gained attention in recent years. However, the pathways toward urban sustainability are complicated and depend on local conditions, which need an understanding of the characteristics of urban metabolism (hereafter referred to as “UM”). This study adopts the flow perspective and develops a methodological framework to conduct a local-scale assessment of resource input to an urban system and related consumption, stock, and output. Through categorizing human activities and describing inner flows, a model of urban metabolism is constructed to clarify interrelationships among different sectors within the urban system, enabling the estimation of material dynamics. By determining metabolism profile and resource scarcity, the results reveals how metabolism takes effect on surrounding environment and urban resilience. This methodological framework is demonstrated through a case study of Guangzhou, China. The main characteristics identified are diversified material consumption, high resource intensity, dependence on non-metallic material and fossil energy import, and a high percentage of CO2 emission associated with industrial production. This result is meaningful in understanding the local resource scarcity and driving a regenerative process in Guangzhou, which is an industry-based economy. Advanced policy is further suggested that refers to clean energy use, waste management techniques, rigorous population control, and advanced measures and data sharing platform in urban management. These findings suggest the need to rethink the trajectory of urban development and gain awareness of the need to focus on new local initiatives in resource use optimization.