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Article | WTW Research Network Newsletter

The Sky’s the Limit: Sustainable Aviation

Towards Zero Carbon Aviation

By Daniel Bannister , Hélène Galy and Lucy Stanbrough | March 23, 2023

While there is no silver bullet or one-size-fits-all solution that can switch aircraft manufactures, airlines, and airports to net zero within the next 10 years, the time for planning is disappearing.
Aerospace|Environmental Risks|ESG and Sustainability|Willis Research Network
Climate Risk and Resilience|ESG In Sight

The path to net zero for the aviation sector is a complex yet necessary challenge that no single stakeholder can solve on their own. Direct aircraft emissions alone, globally, account for approximately 3% of all anthropogenic carbon dioxide (CO2) emissions, and while regulators and consumers have raised ambition within the sector, a rapid lift off is needed to meet the goals of the Paris Agreement. A whole host of different measures are required to overhaul both the direct and indirect emissions produced by the entire aviation system (aircraft manufactures, airlines, and airports). With changes needed to: aircraft design, development, testing, and certification, airport vehicular operations and waste management, sustainable clothing for aircraft crew and airport staff, and more.

Towards Zero Carbon Aviation

To support the industry with this challenge – and bringing our clients perspectives to the table – the WTW Research Network (WRN) have been supporting the 3-year Towards Zero Carbon Aviation (TOZCA) project led by Professor Andreas Schäfer at the Air Transportation Systems Lab, University College London. In last year’s review, we shared details on TOZCA, which will examine how the sector can realistically move towards a net zero climate impact global aviation system by 2050, and the costs and emissions trajectories associated with such transitions, looking at changes in technology, fuels, operations, competition, and consumer behaviour that can lead to drastic CO2 emission reductions.

One year on, the team has provided an insightful update of their progress in a peer-reviewed article in Nature Climate Change: “Cost and emissions pathways towards net-zero climate impacts in aviation” (Dray et al., 2022). The key finding from the paper is that while demand for aviation will increase by as much as 3-fold by 2050, 90% decarbonization can still be achieved through continued efficiency gains in aircraft and operations, and using ultra-green fuels derived from biomass or clean electricity. This is encouraging, and yet, the challenge is immense, requiring much coordination and investment (e.g., Figure 1).

Projections (2000 - 2050) of number of production plants required for different alternative fuel types
Middle demand scenario projections of the number of alternative fuel (biofuel-only, purple; biofuel as a bridging fuel to power-to-liquids, yellow; biofuel as a bridging fuel to liquid hydrogen, red) production plants required to achieve net-zero climate impacts in 2050. See Dray et al. (2022) for further details.

Source: 1Cost and emissions pathways towards net-zero climate impacts in aviation. Nature Climate Change, 12(10), 956-962. 2022

Enabling Discussion to Accelerate Action

By design, the TOZCA project has the active support of several industrial partners in the aviation sector. In this group, WTW brings insights on risk management, insurance, and finance. In addition to joining the TOZCA advisory board, the WRN has organised a series of roundtables for a growing community of aviation and aerospace executives.

In March 2022, the first roundtable focussed on the opportunities and risks in transitioning to a net zero-carbon aviation system. This was the first opportunity for a community, led by the science developed under the TOZCA project, to focus and discuss the ambitious, yet realistic, action plans needed for this industry to undergo an orderly transition.

In November 2022, a second roundtable with over 30 experts and leaders from across the industry (insurance, finance, services, public sector, energy, legal, airlines, airports, and academia) focused on how to overcome to hurdles to the transition, and the relative contributions of science, policy, and markets to support the transition to a net-zero aviation system.

Three key areas, vital in driving and advancing change, emerged from the discussion:

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    more meaningful collaboration within the sector and across sectors (e.g., academia, policies),

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    improved communication on the sector’s endeavours to reach its Paris-aligned emission goals and targets, and

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    additional support in the investment and development of methods and technology to deliver such changes.…

While there is no silver bullet or one-size-fits-all solution that can switch aircraft manufactures, airlines, and airports to net zero within the next 10 years, the time for planning is disappearing and the industry will need to instigate take-off on decisions. Figure 1 helps to demonstrate the scale of the energy transition and required infrastructure for commercial-scale synthetic-fuel plants and the underlying renewable-power-generation system – the next 10 years are critical in driving this transition. In 2023 WTW will be doing our part to support the industry in making decisions on investing in the right technologies and understanding factors such as changing consumer behaviours. These decisions as necessary and open the door to some of the most exciting transformation opportunities for the industry – the sky’s the limit for those bold enough to embrace risk and turn it into opportunity.


1 Dray, L., Schäfer, A. W., Grobler, C., Falter, C., Allroggen, F., Stettler, M. E., & Barrett, S. R. (2022). Cost and emissions pathways towards net-zero climate impacts in aviation. Nature Climate Change 12(10), 956-962.


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