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Definitions and implications of climate-neutral aviation

Nature Climate Change volume 12, pages 761–767 (2022)Cite this article

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Abstract

To meet ambitious climate targets, the aviation sector needs to neutralize CO2 emissions and reduce non-CO2 climatic effects. Despite being responsible for approximately two-thirds of aviation’s impacts on the climate, most of aviation non-CO2 species are currently excluded from climate mitigation efforts. Here we identify three plausible definitions of climate-neutral aviation that include non-CO2 forcing and assess their implications considering future demand uncertainty, technological innovation and CO2 removal. We demonstrate that simply neutralizing aviation’s CO2 emissions, if nothing is done to reduce non-CO2 forcing, causes up to 0.4 °C additional warming, thus compromising the 1.5 °C target. We further show that substantial rates of CO2 removal are needed to achieve climate-neutral aviation in scenarios with little mitigation, yet cleaner-flying technologies can drastically reduce them. Our work provides policymakers with consistent definitions of climate-neutral aviation and highlights the beneficial side effects of moving to aircraft types and fuels with lower indirect climate effects.

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Fig. 1: Modelling approach used in this study.
Fig. 2: ERF components of aviation.
Fig. 3: Schematics of the three plausible definitions of climate-neutral emissions identified in this study.
Fig. 4: Changes in temperature by the year 2100 due to aviation emissions only under two different socioeconomic pathways.
Fig. 5: Changes in temperature throughout the twenty-first century under different socioeconomic pathways and technologies.
Fig. 6: CO2 removal rates and volumes contained in the different definitions of climate neutrality for SSP1–2.6 and SSP5–8.5 and different technology scenarios.

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Data availability

The input data to this analysis is publicly available at https://esgf-node.llnl.gov/search/input4mips/. The data output in this study, that is, the raw data of figures, can be accessed under the folder ‘Outputs’: https://github.com/nikibraz/definitions_climateneutral_aviation.git.

Code availability

The code used to generate figures and tables is available at https://github.com/nikibraz/definitions_climateneutral_aviation.git and will be made publicly available upon acceptance.

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Acknowledgements

N.B. is funded through a Doc.CH grant and acknowledges support from the Swiss National Academy of Science. J.W. was funded throughout the duration of this research through an ETH postdoctoral fellowship and thanks the ETH foundation and the Uniscientia Foundation for his funding.

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Author notes

  1. Jan Wohland

    Present address: Climate Service Center Germany (GERICS), Helmholtz-Zentrum Hereon, Hamburg, Germany

Authors and Affiliations

  1. Department of Environmental Systems Science, ETH Zurich (Swiss Federal Institute of Technology), Zurich, Switzerland

    Nicoletta Brazzola, Anthony Patt & Jan Wohland

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  1. Nicoletta Brazzola
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  2. Anthony Patt
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  3. Jan Wohland
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Contributions

N.B., A.P. and J.W. designed the study. N.B. performed the analysis with support from J.W. N.B. and J.W. wrote the manuscript. All authors edited the manuscript and engaged in ongoing discussions.

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Correspondence to Nicoletta Brazzola.

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

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Supplementary Information

Supplementary Methods (containing Supplementary Figs. 1–5 and Tables 1–4), References and Fig. 6.

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Brazzola, N., Patt, A. & Wohland, J. Definitions and implications of climate-neutral aviation. Nat. Clim. Chang. 12, 761–767 (2022). https://doi.org/10.1038/s41558-022-01404-7

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