Assessing urban carbon metabolism using network analysis across Chinese and European cities

Urban metabolism uses the idea that cities are resource consuming systems that are supported by flows of energy and materials, and they produce goods and wastes, which generate greenhouse gas emissions both directly and indirectly. This research builds on other recent applications of input-output and ecological network analyses to urban metabolism with added value of comparing in one study both approaches across Europe and China specifically at the city scale. We use input-output (IO) and ecological network analyses (ENA) in a study of the urban metabolism of four cities, Vienna, Austria, Malmö, Sweden, Beijing and Shanghai, China. Based on economic input-output tables and environmental weighting coefficients, we create a connected network of flows between 17 economic sectors that captures the carbon emissions from transactions in a producer orientation. Ecological network analysis is conducted to identify the main sectors contributing to the direct and indirect carbon emissions in the four cities. Our results reveal these to be Transportation, Manufacturing, and Electricity production. Furthermore, we show that final demand in terms of domestic export is the highest contributor in each city, indicating that each city is a producer overall in the countries' economies generating carbon flows that are consumed elsewhere.