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Pathways to net-zero emissions from aviation

Nature Sustainability volume 6, pages 404–414 (2023)Cite this article

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Abstract

International climate goals imply reaching net-zero global carbon dioxide (CO2) emissions by roughly mid-century (and net-zero greenhouse gas emissions by the end of the century). Among the most difficult emissions to avoid will be those from aviation given the industry’s need for energy-dense liquid fuels that lack commercially competitive substitutes and the difficult-to-abate non-CO2 radiative forcing. Here we systematically assess pathways to net-zero emissions aviation. We find that ambitious reductions in demand for air transport and improvements in the energy efficiency of aircraft might avoid up to 61% (2.8 GtCO2 equivalent (GtCO2eq)) and 27% (1.2 GtCO2eq), respectively, of projected business-as-usual aviation emissions in 2050. However, further reductions will depend on replacing fossil jet fuel with large quantities of net-zero emissions biofuels or synthetic fuels (that is, 2.5–19.8 EJ of sustainable aviation fuels)—which may be substantially more expensive. Moreover, up to 3.4 GtCO2eq may need to be removed from the atmosphere to compensate for non-CO2 forcing for the sector to achieve net-zero radiative forcing. Our results may inform investments and priorities for innovation by highlighting plausible pathways to net-zero emissions aviation, including the relative potential and trade-offs of changes in behaviour, technology, energy sources and carbon equivalent removals.

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Fig. 1: Decomposition parameters and emissions trajectories.
Fig. 2: Decomposition parameters for changes in emissions in GtCO2eq from 2021 to 2050.
Fig. 3: Projected demand for SAFs.
Fig. 4: Costs of near-commercial sustainable aviation fuels with and without CDR.

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Data availability

Data were compiled from open sources (except for aviation’s energy consumption), and the references are mentioned in Supplementary Table 1. The open-source data are available at https://doi.org/10.5281/zenodo.7187059. The only exception is the IEA proprietary data for aviation’s energy consumption65. Historical emissions are from IEA66 and CMP68, while future emissions are calculated based on equation (1). Historical demand is from ICAO73,74, while freight demand is from the World Bank69 and IATA22. Future aviation demand follows assumptions with data from the International Monetary Fund76, ICAO8 and IEA25. Historical energy-intensity values were calculated based on demand data and fuel consumption data from IEA65. Future energy-intensity estimates follow assumptions from Zheng et al.26, ICAO72 and IEA7. Historical carbon intensity is calculated with data from Bosch et al.50, and carbon equivalent intensity is calculated based on Lee et al.6. Future carbon intensities are calculated based on penetration of different SAFs and electric/hydrogen-powered planes.

Code availability

Data processing was done in Excel. The generation of Fig. 4 and Supplementary Fig. 7 of this manuscript were done in R version 4.1.0 and are available at https://github.com/CandeBergero/Code-Fig4-Net-zero-emissions-aviation.git.

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Acknowledgements

C.B. and S.J.D. were supported by the US National Science Foundation and US Department of Agriculture (INFEWS grant EAR 1639318).

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Authors and Affiliations

  1. Department of Earth System Science, University of California, Irvine, Irvine, CA, USA

    Candelaria Bergero & Steven J. Davis

  2. Division of Economics and Business, Colorado School of Mines, Golden, CO, USA

    Greer Gosnell

  3. Innovation and Technology Center, International Renewable Energy Agency, Bonn, Germany

    Dolf Gielen & Seungwoo Kang

  4. The Payne Institute for Public Policy, Colorado School of Mines, Golden, CO, USA

    Morgan Bazilian

  5. Department of Civil and Environmental Engineering, University of California, Irvine, Irvine, CA, USA

    Steven J. Davis

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  1. Candelaria Bergero
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Contributions

C.B. and S.J.D. conceived the study. C.B. performed the analyses with support from G.G., D.G., S.K., M.B. and S.J.D. The writing of the manuscript was done by C.B. and S.J.D., with inputs and revisions from G.G., D.G., S.K. and M.B.

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Correspondence to Candelaria Bergero or Steven J. Davis.

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Bergero, C., Gosnell, G., Gielen, D. et al. Pathways to net-zero emissions from aviation. Nat Sustain 6, 404–414 (2023). https://doi.org/10.1038/s41893-022-01046-9

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