COMMENTARY: Deconstructing the roadmaps – what to expect from aviation emissions reduction plans

Few industries have welcomed the end of Covid-related travel restrictions as much as the global aviation sector. After more than two years of pain, demand is returning, services are ramping up and revenue is flowing again. The recovery has begun, albeit tentatively. But the return to the skies has placed a renewed focus on the industry’s most pressing problem – the reduction of greenhouse gases. As one of the world’s biggest emitters of GHGs, the industry and its regulators have long been trying to address its sustainability issues. In recent years, this has increasingly included the publication of roadmaps to a greener future. These range from Waypoint 2050, by the global industry association ATAG, to the International Energy Agency’s Aviation report and Roland Berger’s Roadmap to True Zero. Some aim to significantly cut carbon levels, while the more ambitious promise a pathway to net zero or even climate neutrality. The question is, how effective are the roadmaps’ decarbonisation levers likely to be? Nikhil Sachdeva of Roland Berger deconstructs the published roadmaps, focusing on the levers they intend to utilise and their potential emissions-reduction impact, and also examines the significant but largely overlooked problem of non-CO₂ GHG emissions.

Global aviation CO₂ emissions plummeted after the outbreak of the coronavirus pandemic in early 2020. Even today, they remain far below Roland Berger’s pre-Covid forecast. Our latest post-Covid forecast shows they are expected to rebound as demand recovers, albeit to a considerably lower level. This is the first time in aviation history that predicted growth in air travel is forecast to become de-linked from a concomitant growth in emissions. This is due to efforts by the sector to decarbonise: investment in new technologies, such as sustainable aviation fuels and hydrogen, are forecast to make it possible.

Source: Roland Berger

However, the assumed effects of radiative forcing from non-CO₂ GHG emissions are even more significant. Like carbon, NO_x, SO₄, soot and contrails absorb energy and contribute to atmospheric warming. These must therefore also be removed if the aviation industry is to not just decarbonise but achieve ‘True Zero’ emissions. Although still poorly understood, with wide error bars and ongoing debate on how best to quantify CO₂ equivalence, the latest research suggests the total radiative forcing impact of non-CO₂ emissions could be three times that of carbon.

Clearly, something needs to be done to address the industry’s emissions problem. The roadmaps, produced by industry groups, regulatory bodies and third parties, have emerged as the basis of potential solutions. They tend to focus almost entirely on decarbonisation, usually citing a continued lack of hard evidence on the reduction of non-CO₂ emissions as the reason for their omission.

Waypoint 2050 (2021): Produced by the Air Transport Action Group, the global commercial aviation sector’s industry association, this roadmap outlines several decarbonisation scenarios that would result in net zero. The three most ambitious lean heavily on SAFs.   

International Civil Aviation Organization Long Term Aspirational Goal report (2022): ICAO, the United Nations’ aviation agency, presents three decarbonisation scenarios (IS1, IS2, IS3), with the most ambitious aiming to cut CO₂ emissions by 87% by 2050 (vs. 2019 levels). It relies mainly on SAFs.

Sustainable Aviation (2020): This is the UK aviation industry’s strategy to achieve net zero by 2050. It is currently focused on market-based measures, specifically the European Union’s Emissions Trading System and ICAO’s Carbon offsetting and reduction scheme for international aviation (CORSIA).   

Destination 2050 (2021): The European aviation industry’s route to net zero is primarily based on improvements in aircraft and engine technologies, especially hydrogen- and electric-powered aircraft. 

Transport & Environment Roadmap To Climate Neutral Aviation (2022): Transport & Environment is a Brussels-based NGO. It promotes zero-emission aircraft as a potential long-term solution, and demand management as the best way to cut emissions in the short term.

International Energy Agency Aviation report (2021): The roadmap of the IEA, a part of the Organisation for Economic Cooperation and Development, places an emphasis on ICAO’s CORSIA scheme and further carbon pricing measures. It has three scenarios, each more ambitious than the next: Stated Policies; Sustainable Development; and Net Zero Emissions.

Roland Berger Roadmap To True Zero (2020): Our roadmap acknowledges that there is no silver bullet to achieving ‘true zero’ emissions, including those from non-CO₂ GHGs. Instead, it offers a five-point plan, the most ambitious of which is investing in new propulsion technologies such as fully electric and hydrogen fuel cell aircraft. In contrast, Roland Berger’s Baseline forecast (2022) is built around evolutionary improvements that have already been announced by industry players, for example the entrance into service of hydrogen aircraft.

In general, the roadmaps agree on the same primary decarbonisation levers: operational and infrastructure improvements; development of aircraft technology (electric, hydrogen powered); uptake of SAF; and the use of market-based measures (offsetting, emissions trading). However, each takes a different view on future technologies, fuels and markets, and applies the levers to different degrees.

But they disagree on which levers, and the extent of decarbonisation, that is achieved. The roadmaps can be split into two categories, based on the effort required to implement them – and indeed the belief systems underlying them. The first are ‘art of the probable’ roadmaps, which present realistic pathways to significantly reduce aviation emissions. These focus on market-based measures and offsetting. The second are ‘art of the possible’ roadmaps. They lay out radical, optimistic strategies that would allow the aviation industry to make a substantial contribution to combating climate change, based largely on SAF and new technologies. This requires a dramatic ramp up of at least one decarbonisation lever.

Source: Roland Berger

As the name suggests, implementation of ‘art of the probable’ roadmaps is realistic as they are based on established or consensus expectations, though they will be challenging nevertheless.  ‘Art of the possible’ roadmaps, meanwhile, are more ambitious and uncertain, relying on the timely and successful development of new technologies. This places them at the very limit of what is possible and means their implementation will be extremely challenging.

So, what are the actual effects of the roadmaps on carbon emissions? In the case of the ‘art of the probable’ category, the roadmaps all lead to a flattening of net CO₂ emissions, typically by around 2040. They forecast emissions ranging from 66% to 160% of 2019-level CO₂ emissions by 2050. This means that in each case, there is a large amount of unmitigated emissions remaining (between 39% and 64% depending on the publication). All of the roadmaps in this category expect that these will have to be addressed through market-based measures and/or offsetting, making them the main decarbonisation lever (with SAF the leading alternative).

Source: Roland Berger

The 2050 forecasts of the ‘art of the possible’ roadmaps are much more optimistic. They range between 0% and 21% of 2019-level CO₂ emissions. The breakdown of emission reduction levers highlights the important role of SAF (ICAO, Waypoint 2050) and aircraft technology improvements (Destination 2050, Roland Berger) in achieving these reductions, as well as the limited need for market-based measures or offsetting.  

Source: Roland Berger

Time will tell which lever proves to be the most successful. Ultimately, commercial viability is likely to play the key role. Regulation and mandates can only carry an industry so far, and technological advancements are neither assured nor guaranteed to be viable in such a highly specialised industry. A combination may well prevail.

No matter what the levers, all emissions-reduction roadmap publishers need to place far more emphasis on the climate effects of non-CO₂ GHGs. These are likely to make a substantial contribution to global warming and the aviation industry ignores them at its peril. If non-CO₂ effects continue to be overlooked, plans to optimise decarbonisation risk worsening their impact.

About the author

Nikhil Sachdeva

Nikhil heads up Roland Berger’s Centre for Aviation Sustainability and is a leading voice in how the aerospace & aviation sectors can achieve climate neutrality.

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Top photo: Airbus

Views expressed in Commentary op-ed articles do not necessarily represent those of GreenAir.

Editor’s note: Nikhil will be making a presentation on roadmaps at the Aviation Carbon 2022 conference in London 17-19 October