The ‘Aviation Net Zero CO₂ Transition Pathways Comparative Review’, which is a joint initiative of the International Air Transport Association (IATA – the global representative body for the airline industry), the Air Transportation Systems Laboratory of the University College London, the Air Transport Action Group, the International Council on Clean Transportation, and the Mission Possible Partnership, has been released. This compares the 14 main roadmaps for aviation’s transition to net-zero carbon emissions by 2050.

The various transition roadmaps are compared in terms of their scope, key assumptions regarding inputs, aviation energy demand modelling, respective CO₂ emissions, and the emissions-reduction potential of each ‘mitigation lever’ (such as new aircraft technologies, operational improvements, sustainable aviation fuels (SAF), and zero-carbon fuels). The review is the first publication to compare the 14 roadmaps. The aim is to provide airlines, policymakers, and all other aviation stakeholders with a convenient and comprehensive source that will give them an improved understanding of the important similarities and differences between the roadmaps, and their views on how aviation will reach net-zero by 2050.

“The ‘Aviation Net Zero CO₂ Transition Pathways Comparative Review’ demonstrates that there are multiple levers that can be used in different combinations to achieve the objective of decarbonising aviation by 2050,” points out IATA senior VP sustainability and chief economist Marie Owens Thomsen. “All these levers will be needed in aviation’s transition. While the impact of each varies across the roadmaps, all roadmaps expect the greatest decarbonisation in 2050 to stem from SAF.”

The contribution of SAF to decarbonisation varies across the roadmaps from 24% to 70%, with a median figure of 53%. The range is so wide because of the uncertainties regarding government support for SAF, investment levels, production costs, likely profits and feedstock availability.

“This report provides airlines, policymakers and all stakeholders with a useful tool to analyse and improve their policy, investment and business choices,” she highlights. “It is particularly important for SAF where strong and urgent public policy support is needed to increase production. Without that, no version of the roadmaps will get us to net-zero carbon emissions by 2050.”

All the roadmaps also forecast that technological developments and improvements in operational efficiency will together account for about 30% of the reduction in emissions by 2050. When it comes to hydrogen and battery-powered aircraft, the forecasts of their role in cutting emissions varies very widely across the different roadmaps, as a result of different assumptions regarding the adoption of pro-hydrogen policies, and the speed of reduction in renewable energy prices (the faster they fall, the more quickly electricity-based technologies can be taken up).

Finally, nearly all the roadmaps forecast that, to reach net-zero by 2050, aviation will need help from market-based measures and carbon capture, in order to deal with residual emissions. Although carbon capture technologies can be seen as ‘out of sector’ for aviation, they are urgently needed by aviation because the CO₂ they will capture will be needed as a feedstock for the production of power-to-liquid aviation fuels.