I've seen a lot of discussion about plane travel from a climate perspective lately, with people arguing that we should try to restructure our lives to fly much less. Avoid business travel, vacation closer to home, visit relatives less, etc. After looking at the numbers, though, I think this mostly doesn't make sense.

Let's take an example round trip flight from Boston to LA. I've flown this many times for work and to visit relatives, and it's maybe on the long end for a vacation flight. Taking into account that emissions at high altitude are worse than at ground level, that's about 1.3T CO2e [1].

The thing is, 1.3T isn't that much! For example, carbon offsets are about $10/T, so this would add just ~$13 to your ~$500 round-trip flight. Or, if you don't trust offsets and would rather use the full social cost of carbon, that's ~$55/T (Wang et. al. 2019) or ~$72. Or, if you want to go all the way to direct air capture, that's ~$160/T (Keith et. al. 2018) or ~$210.

If you consider a typical BOS-LAX business trip, with, say, $500 for flights, $500 for lodging, $100 for food, and 14hr time lost to travel, a carbon cost of even $210 is rarely going to make the difference on whether the travel is worth it. Even for a vacation, where people tend to be more price sensitive, it's a factor but not nearly the biggest factor.

Climate change is a real problem, and I'm not saying we shouldn't change anything. I favor a stiff carbon tax, high enough to cover the full social cost of emissions. But even under a high tax, most of the things people fly for today would still be worth flying for.

[1] I tried three different calculators and got 1.16T, 1.4T, and 1.36T.

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This argument does make sense and makes me wonder what other reasons there are for me to avoid flying if I accept that the impact of CO2 is solvable without excessive additional costs. What comes up is :

  • Not trusting the bought compensation. [This does not hold up on reflection: Given some research, I am confident that I would find trustworthy organisations such that I could be confident that the social costs are being addressed]
  • The feeling that 'just paying for the costs' is only an excuse and that actually I would be defecting. [This seems to just be caused by my emotions not following the inferential steps needed to realize that 'the harm I inflict' is actually taken care of]
  • Signalling to others the willingness of accepting non-trivial inconveniences when it comes to my behaviour affecting climate. [This aspect seems to be the most important. Even though not flying might not actually be a good way of having a positive influence regarding climate change, it *is* a simple and clear signal that I care about my influence on climate change.]

To conclude, I will update towards 'flying can easily be worth the CO2' and keep an eye out for alternative ways of signaling 'this topic is important to me' ('I do not fly' has the convenient properties of being i) easy to understand, ii) fast to transmit and iii) neither trivial nor too radical).

My 2 cents.

Climate is a global problem. Can only be solved by governments - and multiple governments working to solve it.

Any private action is a waste of time. And contributes to the illusion that something has been done. Which has a massive negative value.

There might be social etc effects of private actions.

Solving a global problem by tilting once own nose in some direction is laughable.

The next question is, why aren't people buying the offsetting? I seem to remembering hearing that it was once an option in most ticket purchase processes, but it must have been an unpopular choice, because the option has disappeared and now offsetting is going to be legally mandated, but apparently the legal mandate does not require enough offsetting to be done (past discussion: https://www.lesswrong.com/posts/XRTiojqqJ3wrFFZAf/can-we-really-prevent-all-warming-for-less-than-10busd-with#EbEWLtgcLQXzHjzCb )

Has there been any discussions of the carbon costs of saving lives? e.g. you save an estimated 100 lives via AMF donations, how much do you need to donate to CATF to offset that? It might help people balance the causes they care about.

In some ways that's the opposite of how I think about it. If you're considering spending money to make the world better, my view is you should spend that money on whatever most improves the world. If you think that is AMF donations, you should just do that. If you think that is carbon offers, or carbon tax advocacy organizations, you should do that instead.

The main model I can think of where you should both give to AMF and also buy offsets for it is one where you're trying to promote a norm that everyone should offset the emissions that come from their decisions. I don't think this norm is likely to catch on, and I think a tax is a much better way to implement something similar.

Thanks for the helpful reply!

Quick estimate: Global average is 4.8 tons per person = $50 additional per year per life saved = ~$1500 total (over 30 additional years of life), so over the course of saving an average person's life the costs if you're buying offsets are the same order as the costs of saving a life via a Givewell charity (~half).

For the people helped by Givewell recommended charities, the additional CO2 emissions are probably lower; among the world's poorest, <1 tons of CO2 per capita per year is pretty common, which is <$300 over a lifetime, about an order of magnitude less than the cost of saving a life.

It sounds like you're assuming that averting the death of a child means there will be an additional person in expectation? Instead it looks more like parents have a target number of kids: https://davidroodman.com/blog/2014/04/16/the-mortality-fertility-link/

Thanks for the helpful reply!

Thanks for doing the math on that! That's really useful information. I was under the impression that flying was a bigger issue than those numbers suggest--I hadn't ever bothered to do the calculation myself.

One reason the low cost of carbon offsets might not make it feel okay to fly is if you're trying to think about what behaviors and habits would still be acceptable in a society that is already functioning carbon-neutrally. My intuition is that as regulations become stricter and greenhouse-gas-reducing projects need less crowdfunding, carbon offset prices will rise until they equal the cost of capturing and sequestering the CO2, which is on the order of several hundred dollars per tonne. So it's hard to imagine a future in which flying is still okay at prices even close to what they are today.

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If you have another look at the post, I talk about how flying would still make sense in many cases at carbon capture costs.

[+][comment deleted]3y1