> So, to me,the dominant effect here is less demand for air travel->fewer flights. Fewer flights means less carbon emitted. Any knock-on effects seem to pale in comparison because air travel is so carbon intensive.
> If fewer flights is a "second order" effect here, I'd struggle to name anything that is a first order effect. I don't really think this is what the person I was responding to was talking about when they mentioned second order effects. But if it was then I question the usefulness of the terminology.
I'm confused; I don't see how your interpretation arises from what I laid out.
I'll see if I can rephrase and clarify.
The first order effect is that less people are flying specifically because of the pandemic. This doesn't immediately result in fewer flights because air schedules are meticulously planned in order to maintain specific routes, which is why oftentimes at the beginning of the pandemic many planes were flying almost entirely devoid of passengers. In essence, the airlines were hemorrhaging money because their flight schedules were planned months/years in advance by anticipating certain flight loads, and all of that was turned sideways in less than 6 weeks.
The second order effect is that airlines start factoring in the risk of a protracted outbreak with no foreseeable end and therefore start making longer-term strategic decisions adjusting to the sustained (years-long) impact of less flights being booked. New routes, canceled routes, different purchasing decisions for planes, different decisions around how to equip those planes and for which classes of clients, folding some operations in some cities altogether, consolidating operations, etc., and these changes will likely result in airlines having to extract more value from the fewer passengers who do have to fly....
> ...which loops (to the OP's point) back into keeping more people from flying as a third-order effect.
...and therefore potentially contributes towards sustained reduced impact on the environment due to less flights being flown globally, greater fuel efficiency of new jets, and less fuel being burned as a result of both.
Hope this helps.