Many actors perceive and describe air travel as the most harmful mode of transport, based on carbon intensity, i.e. in g CO2e per kilometer and per passenger. Figures vary widely: for example, 55 g CO2/passenger.km for a car, and 285 for an airplane1 . Perceptions of the real situation built on these figures lead to information flows and influence operations targeting the airline industry. The British government presents other figures: 246 g CO2/passenger.km for a domestic flight, 170 for a petrol car, 148 for a long-haul flight, or 47 for an electric car2 , these figures being corrected to take account of the non-CO2 radiative effects of aircraft, such as condensation trails3 . According to these figures, the carbon intensity of a long-haul flight would therefore be lower than that of a petrol car.
However, far greater disparities exist, since descriptions based on carbon intensity mask a reality that is inescapable when it comes to reducing teleological degeneracies and setting priorities for energy transition policies: the actual quantities of greenhouse gases (GHGs) emitted by the different modes of transport.
For France, the Citepa 2024 report indicates that domestic road transport in France emitted 119.2 million tonnes of CO2e in 2023, and domestic air transport 4.5 (Figure 1), while international air transport departing from or arriving in France emitted 16.3 million tonnes of CO2e. However, these international emissions include both freight and passenger emissions, with the DGAC indicating4 that 56% of passengers on international flights reside in France, and 44% abroad. The emissions attributable to freight and to the 44% of passengers residing abroad should therefore be subtracted from these 16.3 million tonnes of CO2e.
Furthermore, the Citepa report follows UNFCCC reporting requirements, and does not take into account the climatic effects of contrails: the assessment of radiative forcing due to non-CO2 effects is uncertain, with some authors considering that it could represent 66% of total aviation forcing5 . Finally, taking all these details into account, it appears that air transport actually emits considerably less GHG than road transport, and cannot be described as the most harmful mode of transport.
In addition, a proposal to limit each individual to four air trips in a lifetime, based on the idea that air travel is the privilege of a certain elite, has created controversy. In practice, such a measure would be detrimental to many people: once the quota had been reached, humanitarian workers would no longer be able to work on missions, and expatriates and diasporas would not be able to see their families again. As far as France is concerned, it would generate major conflictuality with overseas France: the Baku initiative group6 would no doubt immediately use this measure to reinforce its retro-colonialist discourse and exacerbate divergences and conflictuality in the West Indies and New Caledonia. And indeed, the General Secretariat for Ecological Planning, aware of the importance of territorial continuity with overseas territories, has wisely reiterated the need to maintain and develop7 flights to these destinations.
On the other hand, private jet users would be the first to escape these quotas, since it is currently possible to build light electric aircraft, which is impossible for commercial aviation due to the battery weight. Hence the need to step up policies to develop the hydrogen sector, which is essential to the development of low-carbon commercial aviation, and, moreover, to a real energy sovereignty.
Measures as extreme as banning air travel are based on a partial, ideologized representation of reality (i.e. an axiological subjunction). This kind of discourse can damage the overall image of energy transition actors and generate divergences which could undermine public support for the transformation policies needed to combat global warming, which could reduce the power of the political actors in charge of the transition.