Identifying channels of environmental impacts of transport sector through sectoral linkage analysis

Considering sectoral linkages with the transport sector during the process of its low-carbon transition is critical for meeting the emission reduction targets of the whole economy. However, the precise roles of different transport modals and their sectoral linkages and transfer mechanisms in driving carbon dioxide (CO₂) emissions are unknown. This study proposes a framework integrating the hypothetical extraction method (HEM) and structural path analysis (SPA) to explore the CO₂ emission characteristics of the transport sector. Based on the above framework, we not only identify the emission sources and destinations related to various transport sub-sectors, but also reveal key channels through which emissions are transmitted along the economic network. Taking China as an example, we find there are heterogeneous characteristics of CO₂ emissions in different transport modals, in which the railway passenger transport sector and the water passenger transport sector are CO₂ emissions importers while other transport sub-sectors are CO₂ emissions exporters. Furthermore, the transport sector mainly exports CO₂ emissions to the construction and service sectors and imports emissions from electricity and heat production and supply sector. From the perspective of transfer paths in forward linkages, the main intermediate sectors of passenger transport sectors are service sectors, while those of freight transport sectors are construction sectors. From the perspective of transfer paths in backward linkages, electricity and heat production and supply sector is the main emission source and intermediate sector. When developing sector-specific and supply chain-wide low-carbon policies, it is suggested to consider the sectoral carbon linkages of each transport sub-sector.