Here’s why…
The remaining global CO2 emissions budget, in 2022, for an 83% chance of holding warming to 1.7ºC was, according to the IPCC, 350 gigatonnes (Gt). [1]
Aviation’s share of this global total CO2 budget is 2.5%, or 8.75 Gt. [2]
Australian aviation, in turn, has a 2.7% share [3] of this global aviation total, or a 0.236 Gt CO2 budget.
Since 2022 domestic and international Australian aviation emissions have totalled 0.024 Gt. [4] So Australia’s aviation CO2 budget is now around 0.212 Gt.
If this is shared across the Australian population, we each get an aviation CO2 emissions budget of 8 tonnes, or not much more than a return economy to New York — until the day flying is emissions free. [5]
But — unfortunately — even that is a likely calamitous overestimate of the emissions we can still create and stay safe. For three reasons.
One, because it comes with a way too risky 17% chance of pushing warming past 2ºC, with associated life-as-we-know-it ending climate consequences for us all. [6]
Two, because the IPCC has miscalculated. They thought their budget allowing another 350 Gt of global emissions, would not cause warming of 1.5ºC until 2035 — at the very earliest. But global warming is at 1.5ºC right now. Mainly because the planet-cooling effect of commercial shipping aerosol emissions, that masked warming of around 0.5ºC, has vanished since shipping started burning cleaner, aerosol-free fuel. [7]
And three, because the aviation budget excludes the contribution to extra warming from non-CO2 aviation emissions. [8]
So… sad to say. We can’t fly and land safely.
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Footnotes
[1] https://essd.copernicus.org/articles/15/2295/2023/essd-15-2295-2023-t07.png [2] https://ourworldindata.org/global-aviation-emissions • https://www.iea.org/energy-system/transport/aviation# [3] Most recent non-Covid year reported global/Australian comparison 2016 • Global: 814 million tonnes CO2https://www.iata.org/contentassets/fb745460050c48089597a3ef1b9fe7a8/paper-offsetting-for-aviation.pdf#:~:text=In%202016%2C%20civil%20aviation%2C%20as%20a%20whole%2C,is%20roughly%202%%20of%20man%2Dmade%20carbon%20emissions.&text=On%206%20October%202016%2C%20the%2039th%20ICAO,to%20address%20CO2%20emissions%20from%20international%20aviation • Australia: 22 million tonnes CO2 (domestic & international) https://www.infrastructure.gov.au/sites/default/files/documents/managing-the-carbon-footprint-of-australian-aviation.pdf p11 • or Australian/Global = 2.7%
[4] International aviation emissions 2023 + 2024 https://www.dcceew.gov.au/sites/default/files/documents/national-inventory-report-2022-volume-1.pdf Fig 3.9: 5.5Mt in 2022 extrapolated @ 4.8% to 5.764 in 2023 & 6 in 2024, or 5.5+6 = 11.764 Mt • Domestic aviation emissions 2023 + 2024 https://greenhouseaccounts.climatechange.gov.au : 5.78Mt in 2022 extrapolated @ +3% to 5.95 in 2023 and + 5.95 @ 4.8% (Domestic aviation fuel +4.8% year to September 2024 https://www.dcceew.gov.au/sites/default/files/documents/nggi-quarterly-update-september-2024.pdf p18) to 6.24 Mt, or 5.95+6.24 = 12.19 Mt • 11.764+12.19 = 23.9 Mt or 0.024 Gt [5] https://co2.myclimate.org/en/ • 212,100,000 tonnes /26,660,000 Australian population = 8 tonnes per Australian. [6] https://www.breakthroughonline.org.au/_files/ugd/148cb0_085aaeb2f1a1481789014b8e895ad23b.pdf [7] https://www.tandfonline.com/doi/full/10.1080/00139157.2025.2434494 [8] https://www.transportenvironment.org/articles/airline-contrails-warm-planet-twice-much-co2-eu-study-finds
