Quantifying aviation's contribution to global warming

Klöwer, M, Allen, MR, Lee, David ORCID: https://orcid.org/0000-0002-5984-8861, Proud, SR, Gallagher, L and Skowron, A ORCID: https://orcid.org/0000-0002-9522-3324 (2021) Quantifying aviation's contribution to global warming. Environmental Research Letters, 16 (10). 104027. ISSN 1748-9326

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Abstract

Growth in aviation contributes more to global warming than is generally appreciated because of the mix of climate pollutants it generates. Here, we model the CO2 and non-CO2 effects like nitrogen oxide emissions and contrail formation to analyse aviation's total warming footprint. Aviation contributed approximately 4% to observed human-induced global warming to date, despite being responsible for only 2.4% of global annual emissions of CO2. Aviation is projected to cause a total of about 0.1 °C of warming by 2050, half of it to date and the other half over the next three decades, should aviation's pre-COVID growth resume. The industry would then contribute a 6%-17% share to the remaining 0.3 °C-0.8 °C to not exceed 1.5 °C-2 °C of global warming. Under this scenario, the reduction due to COVID-19 to date is small and is projected to only delay aviation's warming contribution by about five years. But the leveraging impact of growth also represents an opportunity: aviation's contribution to further warming would be immediately halted by either a sustained annual 2.5% decrease in air traffic under the existing fuel mix, or a transition to a 90% carbon-neutral fuel mix by 2050.