Global trade network and CH emission outsourcing.

The intensifying globalization contributes to the anthropogenic methane (CH) emissions outsourcing, a strong greenhouse gas and harmful air pollutant, through the increasingly complex global trade network. However, the CH flow patterns embodied in global traded goods and services have not been interpreted from the perspective of a complex network. In this paper, we integrate global CH emission inventory from the EDGAR (the Emission Database for Global Atmospheric Research) databases, global multi-regional input-output model from the GTAP database, and complex network analysis to reveal the structural characteristics of the global CH flow network (GCFN). In the GCFN, more than one quarter of the global anthropogenic CH emissions in 2014 are associated with international trade. The top 20 economies contribute to about 70% of the total embodied CH emission flows. The GCFNs mainly consist of tripartite patterns centered on China, the USA and Russia. Some emerging countries, such as Thailand and Brazil, also exhibit dominated positions in different kinds of GCFNs. Moreover, the core-periphery structure of the GCFN confirms the existence of a few hub economies associated with a large amount of CH emissions. The results emphasize the multinational cooperation on global CH emission mitigation, and well-focused mitigation policies should be implemented on some key economies.