Alteration of Carbon Fluxes in Cities during Urbanization: Methodology and a Global Investigation

Cities are increasingly important drivers in altering global biogeochemical cycles. Yet, we still have a limited understanding of the magnitudes and patterns of carbon profile in urban areas. The modelling of carbon profile enables the determination of the interactions between urban systems and natural ecosystems. In this study, we develop a systems approach to accounting for both economic and natural sources and sinks of carbon emissions. We quantify the carbon emissions associated with each economic sectors and household consumers and assess how these emissions changes with different climatic and socio-economic conditions between urban systems. In addition, the relationship between ecosystem services and carbon emissions is analyzed. The case study of a set of major global cities indicates that the value of ecosystem services has a negative correlation with carbon emissions. We argue that the modelling of urban carbon profile is vital not only for guiding cities towards more effective actions towards reducing carbon footprint, but also for looking into the changing ecosystem function and services in urban systems during urbanization. Keywords: carbon emissions, ecosystem services; urbanization; global cities