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Highlights • We modified the CO 2 transfer in social-economic system as a metabolic process in ecosystem. • We utilized ecological network analysis to study the flow variation in global, national, and bilateral scale. • We put up a plan to adjust current mitigation targets set by Paris Agreement based on our study results. Abstract A large share of total global CO 2 emissions results from the production processes of internationally traded goods and services. Such emissions have been referred to as virtual or embodied CO 2 flows. Hence, it is important to understand the directions, locations, and drivers of carbon flows resulting from global trade. To analyze these flows, hotspots, divisions of labor, and directions of flows in the global production and consumption web, we applied a multi-national framework based on a combination of multi-region input-output tables with ecological network analysis. We found that the CO 2 flows between the 40 key countries within the network doubled between 1996 and 2011, and the trade-related emission hub shifted from Europe to Asia. We analyzed a large number of CO 2 transfer paths and their changes over time. We found that the United States participated the most in big paths, including those that represent carbon flows between the United States and both developed and developing countries, whereas developing countries such as China and India participated more in the fast-growing paths, and especially in paths between pairs of developing countries. In contrast, traditionally active countries, including Russia and Germany, grew at a slower rate, resulting in a progressively smaller share in the global system. Taking these large and important CO 2 transfers into consideration, we proposed adjustments to the national mitigation targets set by the Paris Agreement. [ABSTRACT FROM AUTHOR]

Abstract Based on framework of urban metabolism, we constructed the energy metabolism networks of the Jing-Jin-Ji region at two scales: urban and sectoral scale. We used ecological network utility analysis to study mutualism and synergism indices for networks at two scales. Analysis results provide theoretical and empirical support for the development of policies designed to promote healthy development of Jing-Jin-Ji region. [ABSTRACT FROM AUTHOR]

CO 2 emission induced by international trade brings a plenty of pressure on global warming. Hence, it is important to understand multi-regional CO 2 flows that result from global trade and flow variation of different paths. After transforming capital flows into CO 2 carbon flows, we built an ecological network model of the global trade system's carbon metabolism. Through ecological network analysis, we identified the direct and indirect effects of temporal CO 2 flows in the network. We found that the total integral flow through the network experienced a remarkable increase during the study period. In addition, total import and export flows of four countries, including US, China, Germany and Russia, turned out to be rather big. Direct flow share was usually beyond 50% between two geographical adjacent countries, while that share was below 50% when two countries are far away. This research reveals the importance role of indirect flows and can therefore provide an empirical basis for adjusting and optimizing global trade network. [ABSTRACT FROM AUTHOR]

With the increasing scale and scope of global trade, the magnitude of the CO 2 flows embodied in goods and services through international trade has aroused great concern among researchers and governments. In this study, we established a global network model of CO 2 transfers from 2001 to 2010 using ecological network analysis and data from the World Input-Output Database for 40 selected countries whose GDP accounted for more than 85% of the total global GDP. Based on the utility analysis, we determined the ecological relationships among the countries involved in the global trade network and their changes during the study period. The analysis revealed that competition and exploitation/control relationships dominated the global network, with each accounting for more than 40% of the total relationships throughout the study period; mutualism accounted for the smallest proportion (less than 4%). More than 80% of the competition and 75% of the exploitation/control relationships were within Europe or involved flows from Europe to North America or Asia. Finland, France, Japan, Greece, and Spain had the largest proportions of competition relationships. In Denmark, Luxembourg, Malta, and Switzerland, exploitation was dominant, whereas in Russia, Indonesia, and India, control was dominant. Our analysis identifies the key nodes of the many adverse ecological relationships within the global CO 2 network and those with more mutual relationships. Our work provides a scientific basis for developing more ecologically sustainable national and global CO 2 flows through trade. [ABSTRACT FROM AUTHOR]

• The hierarchical structure could give information to a low-carbon city. • Energy-related carbon emission of economic activities dominated the system. • Integrated flows indicated the importance of primary consumers and producers. • Beijing's spatial gradients transformed from single-center to multi-center. • Beijing's ecological hierarchy indicated a better organized metabolic structure. An integral analysis of urban carbon metabolism can support efforts to build a more sustainable city: the spatial gradients provide insights into how to guide future land use and cover change, while ecological network hierarchy provide insights into the self-mutualistic interactions of the city's carbon metabolic structure. In this study, we combined a spatially explicit network with carbon budget of energy consumption and land use and cover change in Beijing, China. From 1990 to 2010, energy related carbon emissions accounted for roughly 90% of the city's total. The network's integrated flux decreased at an average rate of 7.5%. The output flux primarily decreased when moving outward from the center through the periphery of southeastern plains and towards the northwestern mountains. In contrast, the input flux increased moving from the periphery to both the center and mountains. The ecological hierarchy was irregular based on both the driving and pull weights for the components of the model, with excessively small producer and decomposer layers and excessively large consumer layers. The changing structure of Beijing's carbon metabolism over time indicated a tendency to a better organized city. Understanding the evolution of these hierarchies during urban development provides a more solid empirical basis for improving use of the urban space and reducing carbon emission. [ABSTRACT FROM AUTHOR]