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Quantifying aviation’s contribution to global warming


Supplementary data and scripts for

M Klöwer, MR Allen, DS Lee, SR Proud, L Gallagher and A Skowron, 2021. Quantifying aviation’s contribution to global warming, Environmental Research Letters, accepted. Preprint 10.1002/essoar.10507359.1


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 0.3-0.8˚C to not exceed 1.5-2˚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 5 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.