Evolution of the global coal trade network: A complex network analysis

摘要

The evolution of the global coal trade flow among countries impacts coal trade systems operation, coal resource exploitation and global carbon dioxide (CO2) emissions. Several strategies of sustainable development to counteract the impacts of the evolution of the global coal trade network (GCTN) have been proposed. However, the effective implementation of such strategies requires a clear understanding of the evolution of the GCTN and its impacts. This paper focuses on the analysis of the features of the evolution of the GCTN. It builds a complex network model of the global coal trade based on the international coal trade data from 1996 to 2015 and especially explores the evolution of the global coal trade from both continuous time series and comparative perspectives. Through network analysis, the main findings obtained are as follows. (1) The GCTN is scale-free, which means that a tiny minority of countries own many coal transportation partners, and a marked majority of countries own a few. (2) Although Japan, India and South Korea were the top three countries in terms of coal traffic volume in 2015, their intermediate function was weak; Russia and Italy lost their intermediate importance over time. (3) There existed an obvious alteration in that the centre of the network moved to Asia from North America and that the uneven flow distribution of the network became more intense. These results suggest that due to the scale-freeness of the GCTN, global policy makers should establish an international policy environment and strengthen the protection of countries that are important for coal trade, which are defined as key nodes in the GCTN and include the USA, China, and India, to ensure the stable operation of the network and maintain coal transport security. In addition, the findings indicate the huge effects of Asia's coal consumption on the global CO2 emissions in recent years. Policy aimed at reducing Asia's CO2 emissions should be adopted for the reduction of global emissions.