航空运输脱碳：准实验的启示（英）

Decarbonizing Air Transport Insights from a Quasi-Experiment Megersa AbateAlessandro BarattieriAlberto BrugnoliFlavio Porta East Asia and the Pacific RegionOffice of the Chief EconomistAugust 2025 Policy Research Working Paper11183 Abstract The US-China direct flights in mid-2023 were only 7 per-cent of those available in mid-2019. This quasi-experimentinforms the debate on air transport de-carbonization. Anestimated structural model shows that re-establishing thepre-pandemic direct connectivity could increase passengersby 387 percent and reduce prices by 63 percent. Moreover,due to the suppression of flights, carbon dioxide emissions decreased by 80 percent. A counterfactual exercise showsthat maintaining pre-COVID connectivity and achievingthe same emissions reduction through a market mechanism(i.e. offsetting), would have resulted in more passengers(+365 percent), lower prices (−60 percent), and lower reduc-tion in consumer surplus (−40 percent) than observed inthe post COVID-19 equilibrium. The Policy Research Working Paper Series disseminates the findings of work in progress to encourage the exchange of ideas about developmentissues. An objective of the series is to get the findings out quickly, even if the presentations are less than fully polished. The papers carry thenames of the authors and should be cited accordingly. The findings, interpretations, and conclusions expressed in this paper are entirely thoseof the authors. They do not necessarily represent the views of the International Bank for Reconstruction and Development/World Bank andits affiliated organizations, or those of the Executive Directors of the World Bank or the governments they represent. Decarbonizing Air Transport: Insights from a Quasi-Experiment∗ MegersaAbate1,AlessandroBarattieri2,AlbertoBrugnoli3,andFlavioPorta3 1WorldBank2WorldBank&ESGUQAM3UniversityofBergamo JELclassification:F10,Q56,R41Keywords:Airtransport,CO2emissions,structuralestimation 1Introduction The growing concern over greenhouse gas (GHG) emissions has positioned the aviation industryat the center of global climate discussions.While aviation accounts today for approximately2.5% of global carbon emissions (Ritchie, 2024), projections estimate that aviation could consti-tute around 22% of global emissions by 2050 (Cames et al., 2015). The industry has committedto achieving “net zero” carbon emissions by mid-century, but the path to decarbonization re-mains highly debated, with policymakers and industry stakeholders discussing the effectiveness,feasibility, and fairness of various interventions. On one end of the spectrum are market-basedmechanisms, such as emission offsetting schemes like CORSIA (Carbon Offsetting and Reduc-tion Scheme for International Aviation), which allow airlines to compensate for their emissionsby investing in projects that reduce carbon elsewhere.1On the other end, are more stringentregulatory measures, such as flight bans or caps on air traffic, which target emissions by re-stricting high-emission activities. Countries like France, for instance, have introduced bans onshort-haul domestic flights where high-speed rail alternatives exist. Recent proposals have alsoaimed at reducing long-distance, high-emission flights (e.g., Van Minder and Milieumaatregelen(2023)), since they contribute significantly more to carbon emissions. These stricter approachesraise concerns about economic disruptions, consumer welfare, and equitable access to air travel.Balancing these competing priorities presents a significant challenge for global aviation policyas the industry strives to align with international climate goals.In this paper, we offer novelinsights on these issues exploiting a recentquasi-experimentand a structural econometric model. Figure 1 reports the dynamics of seats on direct flights connecting the US and China to severalother regions: Europe, Sub-Saharan Africa, and the Middle East. After the global disruptionsdue to COVID-19, the recovery of direct air transport connectivity is observed everywhere, exceptbetween the US and China. The reasons explaining this pattern are potentially related to both supply and demand factors.The closure of Russian airspace to many international carriers in retaliation to Western sanctionsthat closed Western airspace to Russian carriers might play a role as well.2The closures did notapply to all carriers, thus creating potential asymmetries in terms of costs and time involved inconnecting the US and China with direct flights.3These asymmetries, combined with the lackof an “open skies” agreement between the US and China4, are likely important factors explaining the patterns presented in Figure 1. Table 1 shows how the total number of passengers traveling between the US and China inthe second and third quarter of 2023 was 17% of the pre-pandemic level. Importantly, before thepandemic, about half of the travelers between these two countries was using direct connections.In the post pandemic period