2026-07-12

How bad are planes?

In 2019, I read There Is No Planet BThere Is No Planet BMike Berners-Lee’s 2019 handbook on climate priorities — where flying lands among the high-impact personal choices.theresnoplanetb.net by Mike Berners-Lee a couple days before a trip I took to Asheville, North Carolina to visit my mom. I learned not just that planes are bad for the environment, but the magnitude.

One of my favorite philosophies in life is the Pareto PrinciplePareto PrincipleAlso called the 80/20 rule: a small share of causes often drives most of the effect. Named for Vilfredo Pareto’s observation about wealth concentration.Wikipedia: don't waste all your time and effort on the minutiae. Find the points of highest impact. What I discovered is that, among the people I know and myself historically, flying planes eclipses almost all of our other habits. I would say for most people I know, four domestic flights (round trip) each year is quite typical, with international trips at least once every 2-3 years. I personally feel this calculator typically illustrates why I think most flights are simply not worth it.

I also know people who have essentially never been on planes. Most of them simply can't afford it, often to the extent that they haven't even considered traveling for leisure.

Commercial consumer flying accounts for about 2% of the world's CO₂about 2% of the world's CO₂All aviation is ~2.5% of global CO₂ (fossil + land use). With non-CO₂ effects — mainly contrail cirrus — it’s ~3.5% of warming to date. Of that CO₂, ~88% is commercial, ~8% military, and ~4% private; within commercial, ~81% is passengers and ~19% freight. Passenger flying alone is therefore ~2% of global CO₂.Our World in Data Gössling & Humpe 2020 despite benefiting a sliver of the populationsliver of the populationGössling & Humpe (2020): about 11% of the world flew in 2018, at most 4% internationally. The most frequent 1% of people account for more than half of passenger-aviation CO₂.Gössling & Humpe 2020. A huge portion of the global south have either never flown on a plane or it's a very rare, very expensive privilege used for special circumstances such as migrating between countries. Flying and travel to this extent has only been in human lives for the last ~80 years~80 yearsMass commercial jet travel starts in the 1950s (Comet, then the Boeing 707). Aviation CO₂ has roughly quadrupled since the mid-1960s, and its share of global emissions is still rising.Our World in Data, and it's ramped up significantly and isn't stopping. Our great-great-grandparents had to take ships to get across the Atlantic Ocean.

Upsides exist: cultural diffusion, collaboration across borders, a smaller world. If you want to argue that the pros of commercial travel outweigh the cons, fine — but let's at least get the cons right first.

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