> the regulation needs to leave enough room to allow airlines to avoid emission taxes by using carbon-neutral fuel. Where exactly do you expect this carbon neu

> the regulation needs to leave enough room to allow airlines to avoid emission taxes by using carbon-neutral fuel. Where exactly do you expect this carbon neutral fuel to come from? Fuel=energy, and energy doesn't grow on trees. Well technically biofuel can grow on trees but whatever. What seems to be forgotten by many "optimistic" folks is that we NEED to cut emissions TODAY, and reduce them by ~7% a year for the next 30 years, to avoid catastrophic warming and feedback loops. By many measures, today is already too late. Now tell me how we are going to turn these planes carbon neutral today, or even next year, without turning to hypothetical abundant solar energy that will turn atmospheric CO2 into fuel, or turning half of Indonesia's rainforest into palm trees (note that this is not CO2 neutral at all, land change use is one of the biggest culprits today). The only solution available today is grounding some of those planes. They can take off again when magical carbon neutral fuel is abundant enough that we can afford using it to fly at 850km/h.