Materials Cycles Division, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
Graduate School of Environmental Studies, Tohoku University, 468-1 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8572, Miyagi, Japan.
Environ Sci Technol. 2024 Oct 29;58(43):19231-19242. doi: 10.1021/acs.est.4c05658. Epub 2024 Oct 18.
The transportation of freight by land, sea and air underpins the complex network of global trade in physical commodities. Greenhouse gas emissions from freight transportation are a significant component of global emissions and are predicted to grow in coming decades. However, the inclusion of freight transport in emissions accounts and environmental impact studies is often incomplete. Both data availability and difficulties in allocating freight emissions to specific commodity trades contributes to this. In this study, international freight movements by transport mode are estimated from the bottom-up by imputing global freight transport routes. Emissions are estimated from these freight movements and integrated with a global multiregional input-output model. This enables the calculation of carbon footprints that are complete with respect to freight emissions. We estimate that global freight transport emissions contributed 2.8 Gt CO-equiv in 2012, or about 41% of total transport emissions. In general, freight footprints contribute about 9% to national emissions footprints. While trade in physical commodities (such as construction materials, food and fossil fuels) are associated with the largest embodied freight emissions, services (such as public administration, education and health) also require significant freight transport. Using a consumption-based allocation of freight transport emissions allows the decarbonisation of other sectors to be complementary to the decarbonisation of transport through reduction in demand, for example through material efficiency strategies. To drive decarbonisation in maritime transport it is critical to include bunker emissions in national emissions inventories, thereby completing the system boundary.
陆路、海路和航空货运支撑着实物商品全球贸易的复杂网络。货运产生的温室气体排放是全球排放的重要组成部分，预计在未来几十年还将增长。然而，货运在排放账户和环境影响研究中的纳入往往并不完整。这既与数据的可得性有关，也与将货运排放分配给特定商品贸易的困难有关。在这项研究中，通过输入全球货运路线，从底层向上估算了按运输方式划分的国际货运量。从这些货运量估算排放量，并将其与全球多区域投入产出模型整合。这使得能够计算出完整的货运排放碳足迹。我们估计，2012 年全球货运排放贡献了 28 亿吨二氧化碳当量，约占总运输排放量的 41%。总体而言，货运足迹对国家排放足迹的贡献约为 9%。虽然实物商品（如建筑材料、食品和化石燃料）的贸易与最大的货运隐含排放有关，但服务（如公共行政、教育和卫生）也需要大量的货运。通过基于消费的货运排放分配，可以使其他部门的脱碳与通过减少需求（例如通过提高材料效率的策略）来实现运输脱碳相辅相成。为了推动海运脱碳，必须将燃料舱排放纳入国家排放清单，从而完成系统边界。
