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Cost and emissions pathways towards net-zero climate impacts in aviation

Nature Climate Change volume 12, pages 956–962 (2022)Cite this article

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Abstract

Aviation emissions are not on a trajectory consistent with Paris Climate Agreement goals. We evaluate the extent to which fuel pathways—synthetic fuels from biomass, synthetic fuels from green hydrogen and atmospheric CO2, and the direct use of green liquid hydrogen—could lead aviation towards net-zero climate impacts. Together with continued efficiency gains and contrail avoidance, but without offsets, such an energy transition could reduce lifecycle aviation CO2 emissions by 89–94% compared with year-2019 levels, despite a 2–3-fold growth in demand by 2050. The aviation sector could manage the associated cost increases, with ticket prices rising by no more than 15% compared with a no-intervention baseline leading to demand suppression of less than 14%. These pathways will require discounted investments on the order of US$0.5–2.1 trillion over a 30 yr period. However, our pathways reduce aviation CO2-equivalent emissions by only 46–69%; more action is required to mitigate non-CO2 impacts.

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Fig. 1: Model outputs for single-fuel pathways in the middle-demand scenario.
Fig. 2: Middle-demand scenario related model outputs for two combined pathways aimed at minimizing year-2050 aviation climate impact.

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Data availability

The datasets generated during the current study are available from the corresponding authors on reasonable request.

Code availability

A version of the open-source code of the Aviation Integrated Model AIM2015, adjusted to remove confidential data, underlying this study can be downloaded at http://www.atslab.org/data-tools/

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Acknowledgements

A.W.S. and L.D. acknowledge funding from the UK Engineering and Physical Sciences Research Council, research grant EP/V000772/1. Some MIT contributions to this paper were funded by the US Federal Aviation Administration Office of Environment and Energy through ASCENT, the FAA Center of Excellence for Alternative Jet Fuels and the Environment, project 1, 52 and 58 through FAA Award Number 13-C-AJFE-MIT under the supervision of Anna Oldani, Daniel Jacob and Nate Brown. Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the FAA. C.G. acknowledges fellowship and travel support from the Martin Family Fellowship and the Council for Scientific and Industrial Research (CSIR) in South Africa.

Author information

Authors and Affiliations

  1. Air Transportation Systems Laboratory, School of Environment, Energy and Resources, University College London, London, UK

    Lynnette Dray & Andreas W. Schäfer

  2. MIT Laboratory for Aviation and the Environment, Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, MA, US

    Carla Grobler, Christoph Falter, Florian Allroggen & Steven R. H. Barrett

  3. Department of Civil and Environmental Engineering, Imperial College London, London, UK

    Marc E. J. Stettler

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  1. Lynnette Dray
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Contributions

A.W.S., L.D., S.R.H.B. and F.A. conceived and conceptualized the study. C.F., A.W.S. and F.A. conducted the fuel pathway analyses. C.G., M.E.J.S. and S.R.H.B. conducted analyses of climate assessments and contrail avoidance. L.D. led the scenario analysis and integration of technologies into AIM2015. All authors commented on the results and contributed to the manuscript.

Corresponding authors

Correspondence to Andreas W. Schäfer or Steven R. H. Barrett.

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Nature Climate Change thanks Jörgen Larsson and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data

Extended Data Fig. 1

Fuel burn penalty for contrail length avoided related to a fuel-optimized flight baseline.

Extended Data Fig. 2

Middle demand scenario projections of aviation system characteristics with individual technology pathways.

Extended Data Fig. 3

High demand scenario projections of aviation system characteristics with individual technology pathways.

Extended Data Fig. 4

Low demand scenario projections of aviation system characteristics with individual technology pathways.

Extended Data Fig. 5

Middle demand scenario projections of aviation system characteristics with individual technology pathways and fuel mandates, high LH2 and PTL cost sensitivity case.

Extended Data Fig. 6

Relative contribution of each climate forcing pathway for the combined biofuel and LH2 scenario, capturing emissions from 2015 to 2050, radiative forcing (left), temperature change (right).

Extended Data Fig. 7

Relative contribution of each climate forcing pathway for the combined biofuel and PTL scenario, capturing emissions from 2015 to 2050, radiative forcing (left), temperature change (right).

Extended Data Fig. 8

Middle demand scenario projections of aviation system characteristics with biofuel-only and biofuel as a bridging fuel to PTL and LH2.

Extended Data Fig. 9

High demand scenario projections of aviation system characteristics with biofuel-only and biofuel as a bridging fuel to PTL and LH2.

Extended Data Fig. 10

Low demand scenario projections of aviation system characteristics with biofuel-only and biofuel as a bridging fuel to PTL and LH2.

Supplementary information

Supplementary Information

Supplementary discussion, Figs. 1–18 and Tables 1–15.

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Dray, L., Schäfer, A.W., Grobler, C. et al. Cost and emissions pathways towards net-zero climate impacts in aviation. Nat. Clim. Chang. 12, 956–962 (2022). https://doi.org/10.1038/s41558-022-01485-4

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