Promises of "cleaner" aircraft, alternative fuels, technological innovations... Over the past few years, the air transport sector has asserts that it will be able to decarbonize without giving up traffic growth. In other words, keep flying more and more, but with more efficient aircraft and less polluting fuels.
On paper, the idea is seductive. But when it comes to orders of magnitude, does it stand up to the physical reality of resources, energy and climate?
In a report published in February 2026, the associations The Shift Project and AÉRO DÉCARBO have put this issue under the microscope. And their conclusion is clear (spoiler: the problem isn't just fuel).
It's true, aviation is making progress in terms of energy efficiency. Aircraft today consume considerably less per passenger-kilometre than they did 20, 30 or 40 years ago, thanks to aerodynamic improvements, more efficient engines and better optimization of operations.
But the AÉRO DÉCARBO × The Shift Project report reminds us that expected future gains remain limited :
Above all, these improvements must be seen in the light of the air traffic dynamics much faster.
Mechanical result: the sector's emissions increased by a factor of around 3 over the period.
👉 In other words, aviation is improving on a technical level, but it's not the only one. traffic growth has so far largely offset these gains. But the climate doesn't wait. In these conditions, the gradual replacement of fossil kerosene by cleaner technologies alone will not be enough to offset emissions and traffic growth simultaneously.
In speeches, we talk a lot about sustainable fuels (SAF). In principle, these fuels offer an obvious advantage: the carbon emitted during combustion has been previously captured (by plants or industrial processes). But as the report shows, the term covers a wide range of technologies: some have real benefits, others much less so, and some are even more profitable than others. none can be produced on the scale needed without strong arbitration.
In practice, FAS remains a scarce resource, not a panacea. So, depending on the production chain used, the carbon footprint varies greatly, depending on :
The massive substitution of kerosene by SAF therefore implies :
👉 Some processes can significantly reduce emissions compared with kerosene, others much less so, even posing serious environmental problems. SAFs are not a magic solution, but a scarce, heterogeneous and highly constrained resource.
Even if each aircraft becomes cleaner, traffic is growing faster than climate gains. According to international projections, traffic is likely to grow by around +3% per year until 2050.
This represents a doubling of current traffic levels. Logical consequence: even with more efficient aircraft and alternative fuels, the growing volume of flights absorbs most of the emissions savings that could be expected from technological improvement or SAF.
👉 The report makes it abundantly clear: if traffic continues to grow, no technical scenario can sufficiently reduce cumulative emissions. To put it plainly: As long as the question of flight volume remains outside the debate, decarbonizing aviation will remain out of reach. Loïc Bonifacio, spokesman for the AÉRO DÉCARBO association, sums it up as follows: "no SAF, no growth".
The core of the report is based on concrete orders of magnitude based on verifiable physical calculations.
For a passenger to make a round trip Paris-Montreal (≈12,000 km) without fossil kerosene, it would take, per person :
| Alternative supply | Approximate quantity |
|---|---|
| Used cooking oil | ≈ 370 liters (~2 months' collection from a fast-food restaurant and 5 tons of French fries) |
| Low-carbon electricity | ≈ 8,000 kWh (≈ 2 years of household consumption) |
| Lignocellulosic crops | ≈ 1,000 m² (~4 tennis courts) |
👉 These figures, taken from the actual physical yields of the dies, are not remote hypotheses. And they show us that while flying "oil-free" remains possible on paper, it comes at a considerable material costinvisible in marketing speeches.
Another key finding of the report: airlines are not the only ones to covet these resources. Biomass, low-carbon electricity, agricultural or residual surfaces... All these resources are already mobilized by other sectors:
By 2050, global production of liquid biofuels should reach two to three times lower than cumulative demand areas that are difficult to electrify.
Even testing a scenario showing a high allocation to air (30 TWh and 30% of residual biomass mobilized), if traffic increases by 1% per year, Air travel could account for 37% of French emissions by 2050.
A staggering figure when you consider that :
👉 Allocating these resources on a massive scale to air transport necessarily involves trade-offs to the detriment of other essential usesAnd even by "feeding" the air with low-carbon resources, traffic growth makes the equation untenable.
Electric aircraft, hydrogen-powered aircraft... These solutions are regularly put forward to justify the continuation of traffic.
On this subject, the report is cautious but clear:
The hydrogen-powered aircraft, often presented as a solution for the future, is not an operational option today. And according to Safran CEO this is not not to be expected before the 22nd century !
The report does not deny the value of research and innovation. But it underlines a key point: climate trajectories are based on cumulative emissions, not on future promises. The longer action is delayed, the greater the effort required.
Betting solely on future technological solutions, without acting on volumes, means shifting the problem over time.
This is the key conclusion of the report: moderating air traffic is a necessary condition for meeting climate targets.
👉 It's not about abolishing the plane, it's about :
It's not directly in the report, but public data from ADEME, SNCF Voyageurs and other studies make it possible to situate the gap in terms of emissions. per person-kilometre :
| Mode of transport | Approx. CO₂e (g/passenger-km) | Source |
|---|---|---|
| TGV (France) | ~3,2-3,5 | SNCF Voyageurs / ADEME |
| TER | ~23,8 g | Our world in Data |
| Plane (average excluding long-haul) | ~154-246 g | Our world in Data |
| Long-haul aircraft | ~ 148-160 g | Our wolrd in data / Climatiq |
| Comparison | Plane/train ratio |
|---|---|
| Plane vs. TGV (excluding long-haul) | ×45 à ×75 |
| Plane long-haul vs TGV | ×40 à ×50 |
| Plane vs TER (excluding long-haul) | ×6 à ×10 |
| Long-haul aircraft vs. regional trains | ×6 à ×7 |
👉 The plane emits 45 to 75 times more CO₂e per passenger-kilometer than the TGV in France. Even on long-haul routes, airplanes emit around 40 to 50 times more CO₂e per passenger-kilometer than the TGV.
In light of the AÉRO DÉCARBO × The Shift Project report, the answer is unambiguous: no, not credible or compatible with climate objectives.
The report confirms this: relying solely on technical gains, efficiency improvements or alternative fuels, while continuing to increase traffic, is a mistake. physically unfeasible with today's resources.
Like as the Climate Action Network reminds us To focus on alternative fuels or energy efficiency without rethinking the volume of flights is to ignore the fact that resources are already limited, used by other sectors, and essential to a just transition.
👉 In other words: yes, air travel can be improved (and its decarbonization will indeed involve more sober aircraft and less carbon-intensive fuels). But not to the point of offsetting infinite traffic growth. And today, limiting traffic remains the unavoidable adjustment variable if we want to stay within planetary limits. The real question, then, is no longer "how to green the aircraft", but "what collective place we want to give it in a world of finite resources".
➡️ Can we decarbonize air travel without limiting traffic? No. As the report AÉRO DÉCARBO × The Shift Project "Being able to fly without oil: what energy supply for the airline industry?", technological advances and alternative fuels cannot compensate for the continuing growth in flights. Resources (low-carbon electricity, biomass) are too limited, and even if air travel were favored, emissions would remain massive. The report shows unequivocally that reducing air traffic is essential if we are to meet our climate objectives.
| Efficiency gains | Real improvements, but insufficient to offset growth. |
|---|---|
| Sustainable fuels | SAF is useful but very limited and not scalable. |
| Traffic | Projected growth of ~+3%/year cancels out a large part of the climatic benefits. |
| Resource requirements | Replacing kerosene requires large quantities of biomass/energy. |
| Industry competition | Air transport is not alone in needing these resources. |
| Rail comparison | The train emits much smaller orders of magnitude per passenger-km. |
To find out more, don't hesitate to download the full report "Flying without oil: what energy supply for the airline industry? or its synthesis by AÉRO DÉCARBO × The Shift Project!
Issue du monde de la communication et des médias, Sophie est Responsable éditoriale chez HOURRAIL ! depuis août 2024. Elle est notamment derrière le contenu éditorial du site ainsi que La Locomissive (de l'inspiration voyage bas carbone et des bons plans, un jeudi sur deux, gratuitement dans ta boîte mail !).
Convaincue que les changements d’habitude passent par la transformation de nos imaginaires, elle s’attache à montrer qu’il est possible de voyager autrement, de manière plus consciente, plus lente et plus joyeuse. Son objectif : rendre le slow travel accessible à toutes et tous, à travers des astuces, des décryptages et surtout, de nouveaux récits.
