A new analysis of over 27 million flights has found that global aviation emissions could be slashed by 50-75% through three straightforward efficiency measures.
The study, co-led by the University of Oxford, examined every commercial flight in 2023 and found that emissions per passenger varied by nearly 30 times between the best and worst routes, with a global average of 84.4 grams of CO₂ per passenger-kilometre.
The research identifies three powerful levers for change. First, aircraft model choice is critical. Emissions range from 60 to 360 grams per passenger-kilometre depending on the plane. By flying only the most efficient models, such as the Boeing 787-9 for long-haul and Airbus A321neo for shorter routes, airlines could achieve fuel savings of 25-28%.
Second, seat configuration has a major impact. Premium seats are up to five times more carbon-intensive than economy seats and removing them to create all-economy layouts could cut emissions by 22-57% on some flights by carrying more people in the same space.
Third, filling planes matters. The average global passenger load in 2023 was 79%. Increasing this to 95% would deliver a further 16% emissions reduction.
Co-author Dr Milan Klöwer (Department of Physics, University of Oxford) said: ‘Our results clearly show that efficiency-focused policy could swiftly reduce aviation emissions by more than half, without reducing flight numbers or waiting for future fuels. These are tools that we can use right now.’
Combined, these measures could reduce aviation’s carbon footprint by half to three-quarters. Crucially, the study highlights a fast-start opportunity: airlines could cut emissions by approximately 11% immediately by simply deploying their most fuel-efficient aircraft on the routes they already fly, without purchasing new planes.
The researchers propose policy tools to drive this shift, such as airline emissions ratings, landing fees based on aircraft efficiency, and carbon intensity caps – —similar to standards used for cars and appliances. The least efficient flights were found in Africa, Oceania, and North America, while Brazil, India, and Southeast Asia operated the most efficient networks.
This data-driven roadmap suggests that deep emissions cuts in aviation are achievable with current technology, requiring smarter operations rather than a complete technological overhaul.
Dr Klöwer added: ‘While economically and practically unfeasible to replace all older aircraft short term, this analysis shows the potential more efficient aircraft have in comparison to other efficiency gains. Realistically, this would be a long-term transition – one that could be promoted by policies that reward efficiency, so that the most efficient aircraft are favoured whenever replacement decisions are made.’
The full research can be read here
Photo: Andrés Dallimonti
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