In 2022, the International Civil Aviation Organization (ICAO), the UN agency governing civil aviation worldwide, agreed to a goal to achieve net-zero carbon dioxide (CO₂) emissions from international aviation by 2050. This ambitious goal will likely require up to US $5 trillion in investments in clean aircraft and fuels. Governments and industry have begun implementing the agreement. Since that work has started, how’s it going?

The ICCT’s Aviation Vision 2050 report analyzed the technologies and policies needed to achieve net-zero aviation by 2050. The study projected airline CO₂ emissions through 2050 under four scenarios:

1. Business As Usual (BAU): A continuation of the status quo.
2. Action: Coordinated efforts by governments and industry to cap aviation CO₂ below 2019 levels by 2050.
3. Transformation: Concerted efforts by governments and industry to shift from fossil fuel use starting in 2035 and nearly halve 2050 aviation CO₂ compared to 2019 levels.
4. Breakthrough: Early, aggressive, sustained government intervention that triggers widespread investments in zero-carbon aircraft and fuels, peaking fossil fuel use in 2025 and zeroing it out by 2050.

The figure below shows our projections through 2050 of annual CO₂ emitted by airlines (top) and cumulative CO₂ over time (bottom). The far-right scale on the lower chart shows how cumulative emissions relate to global temperature targets. Under the most ambitious Breakthrough scenario, airlines emit near-zero CO₂ by 2050 and hew to an emissions pathway consistent with 1.75 °C, assuming that airlines maintain their 2019 share of CO₂ (2.9% on a well-to-wake basis). In contrast, both the BAU and Action cases consume a 2 °C warming carbon budget by 2050, and emissions continue on an upwards trajectory. The Transformation case is largely consistent with a 2 °C budget.

Figure. Well-to-wake global aviation CO₂ emissions by scenario and traffic forecast, annual (top) and cumulative (bottom), 2020–2050. The solid lines depict the central traffic forecast, while the shaded areas depict the range between the low and high forecasts.

To understand how the sector is progressing two years later and what additional steps are needed, we need more background on how aviation emissions are calculated. Broadly, we project aviation emissions over time as a product of fuel carbon intensity (g CO₂/MJ of fuel), aircraft energy intensity (MJ/revenue passenger kilometer, or RPK), and traffic (RPKs):

Our report identified key measures that can influence these three factors. Broadly, these include sustainable aviation fuels (SAF), zero emission planes (ZEPs) powered by hydrogen or electricity, efficiency measures, traffic, and economic incentives like carbon pricing. SAFs and ZEPs work to cut fuel carbon intensity, while new efficiency measures like purchasing aircraft and improving load factors reduce aircraft energy intensity over time. Traffic is influenced by numerous factors, including economic growth, airline pricing strategies, and public policies like carbon pricing, which can modulate traffic growth by increasing ticket prices.

With these levers in mind, how are things going for aviation? In short, we’re starting to see some Action, especially in the European Union (EU), but there is no Breakthrough yet in sight.

Legally binding SAF requirements in Europe, Indonesia, and Brazil, along with mandates under development in the United Kingdom and Japan, are consistent with 2% global SAF uptake by 2030. Non-binding goals (including ICAO’s aspirational goal of 6% SAF in 2030, select carrier commitments, and the Inflation Reduction Act tax incentives in the United States) could potentially bring 2030 volumes up to the assumed Action level of 3% SAF by 2030.

Electric aircraft, which we project will potentially cover a small (up to 0.2%) share of aviation RPKs by 2050, have hit turbulence; many startups are pivoting to hybrid electric designs instead. Airbus has rolled back plans to develop a narrowbody hydrogen aircraft and is now focusing on putting a smaller regional aircraft into service by 2035. Generally, these developments are consistent with the expectations of our BAU and Action scenarios, which assume no ZEP penetration.

The International Air Transport Association projects no reduction in the energy intensity of airlines between 2019 and 2024 due to the lingering impacts of COVID-19. Longer-term, Airbus and Boeing are working to develop next-generation narrowbody planes that reduce fuel burn by 20%–25% relative to current (A320neo and 737MAX) aircraft types. This aligns with our Action case, assuming similar technologies would be applied to widebody aircraft soon thereafter.

Post-COVID traffic has rebounded faster than expected; it’s forecasted to have exceeded 2019 levels in the first quarter of 2024, almost a year earlier than anticipated.

Finally, on carbon pricing, the EU Emissions Trading System is the only game in town. It covers about 17% of global passenger aviation CO₂ and includes some recycling of revenue to support SAF deployment. Considering the system’s projected 2030 credit price of €147/tonne CO₂, a global average carbon price of $25 is dead on our Action case ($17 in 2030, rising to $33 in 2031). So, there is a mix of BAU and Action here.

The table below summarizes how these levers relate to our Vision 2050 scenarios. Overall, airlines seem to be hewing to our Action case, which implies they are cutting CO₂ below the BAU scenario but are still on a trajectory to consume a 2 °C warming emissions budget by 2050, with more warming afterwards. In other words, they are not yet on a net-zero pathway.

Table. Decarbonization lever versus Vision 2050 scenario

 

Metric	Measure	Vision 2050 scenario
		BAU	Action	Transform	Breakthrough
Fuel carbon intensity (gCO2/MJ)	Sustainable aviation fuel
	Zero emission planes
Aircraft energy intensity (MJ/RPK)	Fuel efficiency
Activity (RPK)	Traffic growth
	Carbon pricing

Clearly, governments and airlines need to do more to make the aviation sector compliant with the Paris Agreement. But what specifically could they do?

Options include broader moves to obligate SAF use outside of Europe via mandates or low-carbon fuel standards, with robust safeguards for feedstock integrity. Additional efforts would be needed to accelerate the development of short- and medium-haul hydrogen combustion aircraft, which could cover about one-third of global RPKs (a much larger share than regional aircraft). To address energy intensity, ICAO is already working to develop a stronger aircraft CO₂ standard by 2025: a proposal that is both ambitious and flexible could guide manufacturer investments toward developing more fuel-efficient aircraft. Finally, governments should consider expanding carbon pricing to cover more airlines, with revenue recycling to support technology development, if they hope to achieve net-zero aviation.

Without progress on these fronts, policymakers may need to think more broadly about how to shift airlines toward a Paris-compliant future. Additional tools that may need consideration include: 1) demand management to reduce traffic growth, 2) carbon capture to take CO₂ out of the atmosphere and permanently store it, or 3) work to reduce short-lived climate pollutants, notably contrails (we’ll share more on this soon).

So how’s the race toward net-zero aviation going? It’s off to a decent start in Europe, with the rest of the world mostly still limbering up at the start line. It’s time now for other governments to learn from the European Union’s experience, and for all of us to consider what supplemental measures will be needed.

Author

Dan Rutherford
Senior Director of Research

Related Publications

VISION 2050: ALIGNING AVIATION WITH THE PARIS AGREEMENT

Analyzes scenarios under which the aviation sector could achieve emissions reductions in line with the goals of the Paris Agreement.

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SectorAviation

SeriesVision 2050

RegionGlobal

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Sen and Miller (2023) demonstrated that a scenario of Ambitious ZEV Sales encompassing a full phaseout of sales of new non-ZEV vehicles globally by 2045 can ensure that the road transport emissions trajectory is compatible with a 67% likelihood of achievement of a below-2°C pathway without overshoot. This study shows that a combination of additional strategies in the “All Out” scenario could further reduce emissions in line with a well-below 2°C pathway with the same parameters. This is similar to what a previous ICCT study, Graver et al., (2022, found is achievable for the aviation sector, but is still far from a pathway that aligns with 1.5°C. The sizeable work that remains is underscored by another finding of this study, that projected CO2 emissions from vehicles that are already on the road today would exceed the limited carbon budget remaining to avoid overshoot of 1.5°C. Indeed, the cumulative emissions from selling no new vehicles going forward are only 10 billion tonnes lower than the All Out scenario when no other measures are implemented.

Ending all car sales tomorrow is not a feasible option, but the strategies identified in this paper are, and are nearly as effective. In particular, Ambitious ZEV Sales for new vehicles combined with restricting the age of used vehicle sales to no more than 5 years for light-duty vehicles and no more than 8 years for heavy-duty vehicles (both with a three-year dispensation for Africa) could avoid an additional 61 billion tonnes of cumulative CO2 emissions globally; this contributes 42% of the emission reductions in the All Out scenario, more than any other two strategies combined. But it also highlights the scale of the challenge in reducing emissions from new and used vehicles in time to avoid overshoot of 1.5°C. While some additional strategies could be considered in future studies, carbon removal technologies may also need to play a role if in-sector efforts are not able to bridge this gap.

Additional Materials:
Expanded Methodology: Data and methods of analysis used in developing strategies to align global road transport with well below 2°c

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The 2022 study identified a total cumulative mitigation potential of 100 Gt CO2 between the Baseline and Ambitious scenario in the 2020–2050 time frame, of which announced targets were projected to avoid about 20 Gt CO2; this resulted in an “ambition gap” of 80 Gt CO2. This updated modeling shows that recently adopted policies will avoid about 17 Gt CO2 and following through on proposals and announced EV targets would avoid an additional 25 Gt CO2. Combined, recently adopted policies and announced proposals and EV targets have shrunk the ambition gap to 53 Gt CO2. However, even if a ZEV transition were achieved in line with our Ambitious scenario, a further 62 Gt CO2 would still need to be avoided by 2050 to align with the best chances of limiting warming to 1.7°C. For 1.5°C, an additional 123 Gt CO2 would need to be avoided compared to our Ambitious scenario.

There is additional mitigation potential in a variety of other measures, including avoid-and-shift policies for passenger and freight travel, improving conventional vehicle fuel efficiency beyond current policy targets, accelerating the removal of older vehicles from the fleet, and adjusting used vehicle import policies to accelerate ZEV uptake. The ICCT is partnering with the International Energy Agency, the International Transport Forum, the Institute for Transportation and Development Policy, and the United Nations Environment Programme to research additional mitigation strategies that will build on this study.

The post Vision 2050: Update on the global zero-emission vehicle transition in 2023 appeared first on International Council on Clean Transportation.

Three decarbonization scenarios—Action, Transformation, and Breakthrough—are analyzed along with a Baseline scenario, each built around six important parameters: (1) traffic; (2) aircraft technology; (3) operations; (4) zero-emission planes (ZEPs); (5) sustainable aviation fuels (SAFs); and (6) economic incentives.

Detailed findings of the study include:

• In the most ambitious (Breakthrough) scenario, early and sustained government intervention triggers widespread investments in zero-carbon aircraft and fuels, peaking fossil jet fuel use in 2025 and zeroing it out by 2050. Aviation CO₂ is cut by more than 90% below 2019 levels in 2050; cumulative emissions are consistent with 1.75ºC pathway under which aviation doesn’t increase its share of a global carbon budget.
• SAFs account for the largest share of CO₂ reduction potential, varying between 59% and 64% across scenarios. Improvements in aircraft technical and operational efficiency contribute an additional one-third of CO₂ mitigation. Zero-emission planes powered by hydrogen account for up to 5% of emission reductions in 2050.
• Under all scenarios, fuel and ticket costs rise along with the introduction of SAFs. Under the Breakthrough scenario, fuel costs increase by 34% and 70% in 2030 and 2050, respectively, due to the adoption of these more expensive fuels. Thus, policies like a SAF mandate, low carbon fuel standard, carbon taxes, and/or a frequent flier levy will be needed to bridge the price gap between alternative and fossil jet fuels.

Overall, we conclude that new technologies under development can cut aviation CO₂ to near zero in 2050, but that immediate action is needed from governments to peak emissions this decade to put aviation on a 1.75ºC pathway. Either atmospheric carbon removals or curbs to traffic growth will be needed to meet a 1.5ºC temperature pathway.

Figure. Cumulative global aviation CO₂ emissions under various modeling scenarios, 2020-2050

This paper was revised on 30 June, 2023 to correct captions on Figures 10 (ES-2) and B-1 and to amend an estimate of projected ticket price increases. After taking into account fuel efficiency gains through 2050, ticket prices are expected to rise by about 6% under the Breakthrough case. The original can be found here.

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And greenhouse gas emissions do not even fully describe the environmental challenges posed by rising demand for transportation in a system that remains dependent on burning fossil fuel. The public health toll of air pollution, especially in large cities, remains unacceptably high. More than 90% of the world’s population lives in areas that do not meet the air-quality guidelines set by the World Health Organization—including places, like parts of the United States and Europe, that do not habitually think of themselves as suffering from air pollution.

Climate and health impacts are inherently coupled. The bottom line is that a sector almost exclusively dependent on a single energy source, petroleum, operating on infrastructure that represents trillions of dollars of investment, must change substantially in little more than a generation.

Many people have engaged these problems. Policymakers at all levels of government are working to implement new environmental protections and other measures. The automotive industry is investing in the development and deployment of new technologies. Philanthropies are directing large sums to support climate action. Advocacy and consumer groups are launching campaigns to raise awareness and put pressure on decisionmakers. Scientists and academic institutions are conducting research and analyses to support decision-making.

The ICCT works with all these stakeholders. This document summarizes our own vision, reached after long internal deliberation, for decarbonizing the transport sector. Vison 2050 addresses four central questions:

1. What is the baseline trajectory of global transportation emissions from 2020 to 2050 by country and by vehicle segment?
2. What is the magnitude of reductions needed if the global transport sector is to contribute to keeping global temperature rise below 1.5˚C?
3. What is an ambitious yet feasible set of policies and technologies for decarbonizing the transportation sector by mid-century?
4. What are the highest priority focus areas over the next five years?

For road, air, and maritime transportation it articulates a set of targets for greenhouse gas emissions that we collectively must reach if we are to keep global warming below 1.5º C, and a series of steps that we collectively can take to reach them. In short, it summarizes our strategic approach to meeting the climate crisis.

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