The aviation industry is more than just a transport sector. It’s a powerful global network that shapes societies, drives economies, and has the potential to be a vital catalyst in our journey towards a more sustainable future.
It is also a major global employer, supporting a total of 87.7 million jobs worldwide and providing 11.3 million direct jobs. According to ATAG figures, aviation enables US$ 3.5 trillion in global GDP. If aviation were a country, it would be the 17th largest economy in the world.
But this contribution to the global economy has its environmental cost: Aviation is responsible for nearly 2% of global greenhouse gas (GHG) emissions and 2.5% of energy-related CO2 emissions, translating to about 1 billion tons of CO2 in 2018. While these figures might appear less significant when compared to road transportation (11.9% of GHGs) or livestock farming (5.8%), the impacts of these emissions are disproportionately magnified in the aviation sector.
The effects of flight extend beyond the burning of fuel. Airplanes alter the concentration of several gases and pollutants in the atmosphere, influencing short-term and long-term ozone levels, decreasing methane, and producing water vapor, soot, sulfur aerosols, and contrails (condensation trails). While some of these effects cause cooling, the overall outcome results in a warming effect. Consequently, the aviation sector is believed to account for 3.5% of global warming.
So, this is the challenge we face: maintain the contribution that aviation makes to the world economy, while at the same time reducing, if not eliminating, its contribution to global warming.
Committed to the challenge
The aviation sector already recognizes these problems and is prepared to accept the challenge.
In October 2022, the industry pledged it would reach net zero CO2 emissions by 2050 at the 41st Assembly of the International Civil Aviation Organization (ICAO).
This move followed its pioneering work in 2016 when the ICAO – a UN specialized agency – introduced the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA), under which an airline must offset emissions beyond a baseline by buying credits, with the split based on the airline’s share of total industry emissions.
For the pilot stage, which runs until the end of 2023, the baseline is industry emissions in 2019 and then, from 2024, the baseline will be lowered to 85% of emissions in 2019. Critics have pointed out that airlines may be able to avoid buying carbon credits at all by using a small proportion of sustainable aviation fuel (SAF), made from waste cooking oil, which is heavily subsidized in the US.
But that misses an important point: CORSIA was the first time a single industry sector had agreed to a global market-based measure in the climate change field.
Applauding progress at the global level is not to ignore the contribution that individual countries and associations can make. The European Union (EU), for example, brought aviation into its Emission Trading Scheme (ETS) in 2022. Free allowances that enable airlines to avoid paying for carbon emissions will be phased out by 2026, one year earlier than was envisaged in the European Commission’s original proposal. A decrease of 25% in free allocations is planned for 2024 and 50% for 2025.
Critics of CORSIA point out that carbon credits are far more expensive in the EU scheme than those issued under CORSIA, costing around €90 (US$ 96) a ton, rather than US$ 3 under CORSIA. But the EU scheme is limited by trade concerns, while CORSIA covers most of the world (see graphic) and is expanding. Britain and Switzerland are included, but flights to other countries outside the bloc will remain exempt. This is mostly the result of a stand-off in 2012 when China threatened to stop buying planes from Airbus, a European firm, and America threatened non-compliance if the EU required all flights to take part in its scheme.
The lesson from this may be that initiatives led by the aviation industry itself are more likely to win widespread adoption, rather than geographically based schemes. Yet the industry’s ability to control key aspects of this transformation is limited. Whether it be fuel production, aircraft manufacturing, or the management of airports and air traffic, each component is controlled by separate entities within the complex web of aviation operations. Without coherent agreement between all these different elements, decarbonization is significantly more challenging, but if true collaboration is possible, the aviation industry and its individual players could reap the benefits of scale and synergy to make a real difference.
The signs here are encouraging. Over the past several decades, slower growth in aviation emissions indicates significant improvements in aviation efficiency. In fact, the CO2 emitted per RPK, a measure of aviation efficiency, dropped to around 125 grams in 2018, from a figure twenty times larger in 1950, and eleven times higher in 1960.
The leaps in efficiency over the past half-century are credited to technological and design advancements in aircraft, larger aircraft sizes carrying more passengers per flight, and increased ‘passenger load factors’—the percentage of available seat kilometers (ASK) utilized. In simpler terms, flights today are fuller than before.
Already many companies across the aviation value chain have pledged to a variety of environmental targets. These range from commitments to emission-reduction targets and the adoption of sustainable aviation fuels (SAF), to membership of sustainability-driven coalitions.
One significant example is the Science Based Targets initiative (SBTi), which has a critical role in keeping the aviation industry’s environmental goals in line with the net zero objectives of the Paris Agreement.
SBTi is a joint effort by four influential non-governmental organizations: the Carbon Disclosure Project (CDP), the United Nations Global Compact, the World Resources Institute (WRI), and the World Wildlife Fund for Nature (WWF).
Its mission is to align corporate emission-reduction targets with the scientific consensus for achieving net-zero emissions by 2050. The SBTi has rolled out guidance for an interim aviation 1.5°C pathway. This entails ambitious emission-reduction targets for airlines, demanding a CO2 reduction per revenue ton kilometer (RTK) of more than 30% by 2030 and over 50% by 2035, compared to 2019 levels. This is closely aligned with the targets set by the International Energy Agency Net Zero Emissions pathway.
Currently, 25 airlines have pledged to set or have already established SBTs, though these are predominantly based in the Americas and Europe. Representing over 30% of global passenger traffic, this group’s commitment signals a significant shift towards sustainable practices within the industry. Simultaneously, aerospace and defense companies, accounting for about 20% of the global value pool, have also pledged to align their objectives with the SBTi.
Focus on efficiency
Much of the discussion around curbing CO2 emissions centers around fuel, replacing aviation fuel with SAF or powering airplanes by battery or hydrogen. Yet there are other measures to consider that can be highly effective if stakeholders are prepared to collaborate. For instance, according to a McKinsey analysis, carriers reduced their fuel consumption per passenger-kilometer by approximately 39% between 2005 and 2019 (pre-COVID-19), a compound annual growth rate of about 3.4% per year through fleet renewal, load factor, seat density and fuel efficiency programs.
Already there are two major initiatives underway that will cut emissions through modernizing the air traffic control infrastructure: NextGen in the US and the Single European Sky program. Overseen by the United States’ Federal Aviation Administration, NextGen will introduce ‘performance-based navigation’ to select shorter, more precise flight paths that save fuel. While the EU program removes the national boundaries over shared EU airspace, it calculates adds an extra 49 kilometers to most journeys.
Willie Walsh, Director General, IATA, said:
“You could reduce CO2 in Europe by 10% to 12% through Single European Sky, and it could be done overnight. You don’t need any investment in technology.
We have the technology already in the aircraft to fly the most efficient routes.”
Innovation in aircraft
Another way for airlines to reduce their carbon footprint is by updating their fleets more frequently with newer, more efficient aircraft. This approach, especially when taking into account possible future regulations like obligations to use sustainable aviation fuel or taxes on kerosene, can lower emission levels at a reduced, or even negative, cost.
With the aircraft models available today, airlines can cut their carbon emissions by up to 15% to 20%, depending on the current state of their fleet. In the next 10 years, a significant number of older aircraft will be replaced with next-generation models like the Airbus A320neo and the Boeing 777-X family that are far more environmentally friendly. For example, the A320neo is currently the most fuel-efficient aircraft of its size, offering a 20% reduction in fuel usage and carbon emissions, while the Boeing 777X promises to reduce both fuel consumption and carbon emissions by 10%.
Removing emissions from aviation fuel would contribute to a 65% reduction in carbon emissions from the sector, according to the International Air Transport Association (IATA).
If it were possible, using SAFs would be the most straightforward manner of achieving net-zero emissions by 2050. SAFs can be integrated into existing fuel systems without changing aircraft design or airport infrastructure and compared to conventional fossil-based jet fuel, they can reduce aviation’s lifecycle emissions by up to 80% if they are the sole fuel, rather than being blended with conventional jet fuel as they are at present.
SAFs, as defined by ICAO, are renewable or waste-derived fuels that adhere to sustainability criteria but the definition of an SAF is very important, as recent EU legislation shows. It has set a green fuel mandate for aviation, ReFuelEU, that requires all flights departing from an EU airport from 2025 to use a minimum share of SAFs, starting at 2% in 2025, 6% by 2030, and gradually increasing to 70% by 2050. The mandate prioritizes synthetic fuels (e-kerosene) and excludes controversial biofuel feedstocks like food crops and palm oil by-products, because this could push up food prices or speed up deforestation.
Despite the benefits of SAFs, the economic viability of these fuels remains a challenge – synthetic fuels can be up to 10 times as expensive as jet fuel. As Boeing’s CEO, David Calhoun, says: “There is no cheap way of decarbonizing air travel.”
Some fuel suppliers are already committed to the SAF challenge. For example, Shell has invested in a range of technologies to produce SAFs and is building a biofuels facility in Rotterdam that will produce SAF and renewable diesel from waste, expected to start production in 2025.
Despite these advances, research indicates that SAF supply, even with significant investment and progress in technology, may not meet aviation fuel demand by 2050. The consultancy Bain expects hydro processed esters and fatty acids (HEFA), a type of SAF made from cooking oil and animal fats, to satisfy a maximum of about 8% of jet fuel demand in 2050 due to its limited feedstocks. Synthetic or e-fuels, produced by combining green hydrogen with carbon dioxide, could theoretically offer unlimited capacity, but have not yet been proven at scale, it concludes.
Many hopes for a decarbonized air sector are pinned on hydrogen, a fuel with zero emissions. Green hydrogen—produced via water electrolysis using renewable energy — stands out as a sustainable alternative to kerosene yet, despite its promise and rapidly decreasing production costs, the transition from concept to aviation reality remains challenging.
Airbus raised hopes in 2020 when it announced it would develop a hydrogen-powered aircraft, the ZEROe by 2035.
It was followed by several other companies, including Rolls-Royce, easyJet, and Boeing, that also dipped their toes into hydrogen technology development.
For example, Rolls-Royce and easyJet have initiated ground tests of a hydrogen-combustion aircraft engine, while Airbus collaborated with GE and Safran to equip an A380 superjumbo with a hydrogen combustion engine.
Airbus has even announced plans for a hydrogen fuel cell-powered engine, potentially capable of powering a 100-passenger aircraft, to begin flight tests around 2026.
Electric aviation has a great role to play in the decarbonization of aviation, although not, for the moment, for long-haul flights. It is currently only feasible for relatively short journeys of up to 400 miles.
Dale Vince, the founder of UK energy company Ecotricity, is set to launch Britain’s first electric airline, Ecojet, in 2024. Positioned as the “flag carrier for green Britain”, the airline plans to debut with a 19-seater plane flying between Edinburgh and Southampton.
Initial flights will use kerosene-based fuel, switching to engines powered by green hydrogen in subsequent years.
Meanwhile, Rolls-Royce’s ‘Spirit of Innovation’ aircraft has made significant strides in electric aviation. The company says its all-electric aircraft is the world’s fastest all-electric vehicle, reaching top speeds of 555.9 km/h over three kilometers, and clocking a maximum speed of 623 km/h. The aircraft is part of the ACCEL (Accelerating the Electrification of Flight) project and propelled by a 400kW (500+hp) electric powertrain and propulsion battery pack.
Similarly, Joby Aviation, a California-based startup backed by Abdul Latif Jameel Investment Management Company (JIMCO), the investment arm of Abdul Latif Jameel, has raised significant capital for its piloted, all-electric, vertical take-off and landing aircraft. The four-seater aircraft, which can reach speeds of 320 km/h and cover 240km on a single charge, is intended to offer affordable air taxi services worldwide while generating zero emissions and making little or no sound.
“Air taxi service is still in the early stages of commercialization, but one that has the potential to completely transform the future of mobility,” commented Hassan Jameel, Deputy President and Vice Chairman of Abdul Latif Jameel. “Simultaneously reducing carbon emissions makes this a compelling proposition.”
The mission to decarbonize aviation is undoubtedly difficult and problematic but far from impossible.
The incentives for action are growing as regulation gets tighter while all the stakeholders – fuel suppliers, manufacturers, airports, airlines and freight operators to name just a few – are united in working towards this goal. Meanwhile, technology continues to advance, producing ever more efficient craft that will contribute to the success of this mission. Together these various strands can be plaited together to pull aviation into the carbon-free future that is so urgently needed.