It's debatable. The IEA have an estimate of €190 per tonne. Which is €400 per passenger on a return transatlantic flight (assuming no mark-up). But there are a

It's debatable. The IEA have an estimate of €190 per tonne. Which is €400 per passenger on a return transatlantic flight (assuming no mark-up). But there are already some taxes and surcharges on flights, and some of that is carbon-related, so a "full cost" price wouldn't be €400 more than today's. AIUI they use a "harm" model to try and land on that number, i.e. X gigatons of carbon => Y amount of climate change => Z economic damage. Another way to look at it is "if each tonne of carbon can be burned only once, and in a scenario where future carbon is committed towards manufacture renewables (or nuclear capacity), how many kWh of renewable/nuclear electricity can be bought with 1t of carbon". That yields a much larger number. Or you can look at it through a carbon capture and storage lens. Industrial CCS yields a much lower number, but it's talking about capturing from factory boiler exhaust streams, where you can have the plant capture the CO2 at source. Not an option on a jet airliner. Direct air capture (ground-based stations mopping up aircraft exhaust) is an order of magnitude more expensive, currently in the $1000/tonne range, you're trying to vacuum gas out of the air that's at a 400ppm concentration by mass.