Vasco, I’ve read your post to which the first link leads quickly, so please correct me if I’m wrong. However, it left me wondering about two things:
(a) It wasn’t clear to me that the estimate of global heating damages was counting global heating damages to non-humans. The references to DALYs and ‘climate change affecting more people with lower income’ lead me to suspect you’re not. But non-humans will surely be the vast majority of the victims of global heating—as well as, in some cases, its beneficiaries. While Timothy Chan is quite right to point out below that this is a complex matter, it’s certainly isn’t going to be a wash, and if the effects are negative, they’re likely to be very bad.
(b) It appears you were working with a study that employed a discount rate of 2%. That’s going to discount damages in 100 years to 13% of their present value, and damages in 200 years to 1.9% of their present value—and it goes downhill from there. But that seems very hard to justify. Discounting is often defended on the ground that our descendants will be richer than we are. But that rationale doesn’t apply to damages in worst-case scenarios. Because they could be so enduring, these damages are huge in expectation. Second, future non-humans won’t be richer than we are, so benefits to them don’t have diminishing marginal utility compared with benefits to us.
The US government—including, so far as I know, the EPA—uses a discount rate that is higher than two percent, which makes future damages from global heating evaporate even more quickly. What’s more, I’d be surprised if it’s trying to value damages to wild animals in terms of the value they would attach to avoiding them, as opposed to the value that American human beings do. The latter approach, as Dale Jamieson has observed, is rather like valuing harm to slaves by what their masters would pay to avoid it.
(a) It wasn’t clear to me that the estimate of global heating damages was counting global heating damages to non-humans.
I have now clarified my estimate of the harms of GHG emissions only accounts for humans. I have also added:
I estimated the scale of the welfare of wild animals is 10.9 M times that of farmed animals. Nonetheless, I have neglected the impact of GHG emissions on wild animals due to their high uncertainty. According to Brian Tomasik:
“On balance, I’m extremely uncertain about the net impact of climate change on wild-animal suffering; my probabilities are basically 50% net good vs. 50% net bad when just considering animal suffering on Earth in the next few centuries (ignoring side effects on humanity’s very long-term future).”
In particular, it is unclear whether wild animals have positive/negative welfare.
I have added your name to the Acknowledgements. Let me know if you would rather remain anonymous.
(b) It appears you were working with a study that employed a discount rate of 2%. That’s going to discount damages in 100 years to 13% of their present value, and damages in 200 years to 1.9% of their present value—and it goes downhill from there. But that seems very hard to justify. Discounting is often defended on the ground that our descendants will be richer than we are.
Carleton 2022presents results for various discount rates, but I used the ones for their preferred value of 2 %. I have a footnote saying:
“Our preferred estimates use a discount rate of δ = 2 %”. This is 1.08 (= 0.02/0.0185) times the 1.85 % (= (17.5/9.72)^(1/(2022 − 1990)) − 1) annual growth rate of the global real GDP per capita from 1990 to 2022. The adequate growth rate may be higher due to transformative AI, or lower owing to stagnation. I did not want to go into these considerations, so I just used Carleton 2022’s mainstream value.
I used to think this was relevant, but mostly no longer do:
One should discount the future at the lowest possible rate, but it might still be the case that this is not much lower than 2 % (for reasons besides pure time discounting, which I agree should be 0).
I believe human extinction due to climate change is astronomically unlikely. I have a footnote with the following. “For donors interested in interventions explicitly targeting existential risk mitigation, I recommend donating to LTFF, which mainly supports AI safety. I guess existential risk from climate change is smaller than that from nuclear war (relatedly), and estimated the nearterm annual risk of human extinction from nuclear war is 5.93*10^-12, whereas I guess that from AI is 10^-6”.
I guess human extinction is very unlikely to be an existential catastrophe. “For example, I think there would only be a 0.0513 % (= e^(-10^9/(132*10^6))) chance of a repetition of the last mass extinction 66 M years ago, the Cretaceous–Paleogene extinction event, to be existential”. You can check the details of the Fermi estimate in the post.
If your worldview is such that very unlikely outcomes of climate chance still have meaningful expected value, the same will tend to apply to our treatment of animals. For example, I assume you would have to consider effects on digital minds.
I am open to indirect longterm effects dominating the expected value, but I suppose maximising more empirically quantifiable less uncertain effects on welfare is still a great heuristic.
Thanks, Vasco! You are welcome to list me in the acknowledgements. I’m glad to have the reference to Tomasik’s post, which Timothy Chan also cited below, and appreciate the detailed response. That said, I doubt we should be agnostic on whether the overall effects of global heating on wild animals will be good or bad.
The main upside of global heating for animal welfare, on Tomasik’s analysis, is that it could decrease wild animal populations, and thus wild animal suffering. On balance, in his view, the destruction of forests and coral reefs is a good thing. But that relies on the assumption that most wild animal lives are worse than nothing. Tomasik and others have given some powerful reasons to think this, but there are also strong arguments on the other side. Moreover, as Clare Palmer argues, global heating might increase wild animal numbers—and even Tomasik doesn’t seem sure it would decrease them.
In contrast, the main downside, in Tomasik’s analysis, is less controversial: that global heating is going to cause a lot of suffering by destroying or changing the habitats to which wild animals are adapted. ‘An “unfavorable climate”’, notes Katie McShane, ‘is one where there isn’t enough to eat, where what kept you safe from predators and diseases in the past no longer works, where you are increasingly watching your offspring and fellow group members suffer and die, and where the scarcity of resources leads to increased conflict, destabilizing group structures and increasing violent confrontations.’ Palmer isn’t so sure: ‘Even if some animals suffer and die, climate change might result in an overall net gain in pleasure, or preference satisfaction (for instance) in the context of sentient animals. This may be unlikely, but it’s not impossible.’ True. But even if it’s only unlikely that global heating’s effects will be good, it means that its effects on existing animals are bad in expectation.
There’s another factor which Tomasik mentions in passing: there is some chance that global heating could lead to the collapse of human civilisation—perhaps in conjunction with other factors. In some respects, this would be a good thing for non-humans—notably, it would put an end to factory farming. It would also preclude the possibility of our spreading wild animal suffering to other planets. On the flipside, however, it would also eliminate the possibility of our doing anything sizable to mitigate wild animal suffering on earth.
Now, while there may be more doubt about the upsides than about the downsides of our GHG emissions, that needn’t decide the issue if the upsides are big enough. But even if Tomasik and others are right that wild animal lives are bad on net, there’s also doubt about whether global heating will reduce the number of wild animal lives. And even if both are these premises are met, I’m not sure they’d outweigh the suffering global heating would inflict on those wild animals who will exist.
I think you have misinterpreted what my article about discounting is recommending. In contrast to some other writers, I’m not calling for discounting at the lowest possible rate. Even at a rate of 2%, catastrophic damages evaporate in cost-benefit analysis if they occur more than a couple of centuries hence, thus giving next to no weight to the distant future. However, a traditional justification for discounting is that if we didn’t, we’d be obliged to invest nearly all our income, since the number of future people could be so great. I argue for discounting damages to those who would be much better off than we are at conventional rates, but giving sizable—even if not equal—weight to damages that would be suffered by everyone else, regardless of how far into the future they exist. My approach thus has affinities with the one advocated by Geir Asheim here.
One implication is that while we’re under no obligation to make future rich people richer, we ought to be very worried about worst-case climate change scenarios, since in those humans could be poorer. Another is that since most non-humans for the foreseeable future will be worse off than we are, we shouldn’t discount their interests away.
Thanks for the follow up, Matthew! Strongly upvoted.
My best guess is also that additional GHG emissions are bad for wild animals, but it has very low resilience, so I do not want to advocate for conservationism. My views on the badness of the factory-farming of birds are much more resilient, so I am happy with people switching from poultry to beef, although I would rather have them switch to plant-based alternatives. Personally, I have been eating plant-based for 5 years.
Sorry! It sounded so much like you were referring to Weitzman 1998 that I actually did not open the link. My bad! I have now changed “That paper says one should discount” to “One should discount”.
a traditional justification for discounting is that if we didn’t, we’d be obliged to invest nearly all our income, since the number of future people could be so great.
I do not think this is a good argument for discounting. If it turns out we should invest nearly all our income to maximise welfare, then I would support it. In reality, I think the possibility of the number of future people being so great is more than offset by the rapid decay of how much we could affect such people, such that investing nearly all our income is not advisable.
I argue for discounting damages to those who would be much better off than we are at conventional rates, but giving sizable—even if not equal—weight to damages that would be suffered by everyone else, regardless of how far into the future they exist.
This rejects (perfect) impartiality, right? I strongly endorse expectedtotalhedonisticutilitarianism, so I would rather maintain impartiality. At the same time, the above seems like a good heuristic for better outcomes even under fully impartial views.
Thanks, Vasco! That’s odd—the Clare Palmer link is working for me. It’s her paper ‘Does Nature Matter? The Place of the Nonhuman in the Ethics of Climate Change’—what looks like a page proof is posted on www.academia.edu.
One of the arguments in my paper is that we’re not morally obliged to do the expectably best thing of our own free will, even if we reliably can, when it would benefit others who will be much better off than we are whatever we do. So I think we disagree on that point. That said, I entirely endorse your argument about heuristics, and have argued elsewhere that even act utilitarians will do better if they reject extreme savings rates.
Vasco, I’ve read your post to which the first link leads quickly, so please correct me if I’m wrong. However, it left me wondering about two things:
(a) It wasn’t clear to me that the estimate of global heating damages was counting global heating damages to non-humans. The references to DALYs and ‘climate change affecting more people with lower income’ lead me to suspect you’re not. But non-humans will surely be the vast majority of the victims of global heating—as well as, in some cases, its beneficiaries. While Timothy Chan is quite right to point out below that this is a complex matter, it’s certainly isn’t going to be a wash, and if the effects are negative, they’re likely to be very bad.
(b) It appears you were working with a study that employed a discount rate of 2%. That’s going to discount damages in 100 years to 13% of their present value, and damages in 200 years to 1.9% of their present value—and it goes downhill from there. But that seems very hard to justify. Discounting is often defended on the ground that our descendants will be richer than we are. But that rationale doesn’t apply to damages in worst-case scenarios. Because they could be so enduring, these damages are huge in expectation. Second, future non-humans won’t be richer than we are, so benefits to them don’t have diminishing marginal utility compared with benefits to us.
The US government—including, so far as I know, the EPA—uses a discount rate that is higher than two percent, which makes future damages from global heating evaporate even more quickly. What’s more, I’d be surprised if it’s trying to value damages to wild animals in terms of the value they would attach to avoiding them, as opposed to the value that American human beings do. The latter approach, as Dale Jamieson has observed, is rather like valuing harm to slaves by what their masters would pay to avoid it.
Nice points, Matthew!
I have now clarified my estimate of the harms of GHG emissions only accounts for humans. I have also added:
I have added your name to the Acknowledgements. Let me know if you would rather remain anonymous.
Carleton 2022 presents results for various discount rates, but I used the ones for their preferred value of 2 %. I have a footnote saying:
I used to think this was relevant, but mostly no longer do:
One should discount the future at the lowest possible rate, but it might still be the case that this is not much lower than 2 % (for reasons besides pure time discounting, which I agree should be 0).
I believe human extinction due to climate change is astronomically unlikely. I have a footnote with the following. “For donors interested in interventions explicitly targeting existential risk mitigation, I recommend donating to LTFF, which mainly supports AI safety. I guess existential risk from climate change is smaller than that from nuclear war (relatedly), and estimated the nearterm annual risk of human extinction from nuclear war is 5.93*10^-12, whereas I guess that from AI is 10^-6”.
I guess human extinction is very unlikely to be an existential catastrophe. “For example, I think there would only be a 0.0513 % (= e^(-10^9/(132*10^6))) chance of a repetition of the last mass extinction 66 M years ago, the Cretaceous–Paleogene extinction event, to be existential”. You can check the details of the Fermi estimate in the post.
If your worldview is such that very unlikely outcomes of climate chance still have meaningful expected value, the same will tend to apply to our treatment of animals. For example, I assume you would have to consider effects on digital minds.
I am open to indirect longterm effects dominating the expected value, but I suppose maximising more empirically quantifiable less uncertain effects on welfare is still a great heuristic.
Thanks, Vasco! You are welcome to list me in the acknowledgements. I’m glad to have the reference to Tomasik’s post, which Timothy Chan also cited below, and appreciate the detailed response. That said, I doubt we should be agnostic on whether the overall effects of global heating on wild animals will be good or bad.
The main upside of global heating for animal welfare, on Tomasik’s analysis, is that it could decrease wild animal populations, and thus wild animal suffering. On balance, in his view, the destruction of forests and coral reefs is a good thing. But that relies on the assumption that most wild animal lives are worse than nothing. Tomasik and others have given some powerful reasons to think this, but there are also strong arguments on the other side. Moreover, as Clare Palmer argues, global heating might increase wild animal numbers—and even Tomasik doesn’t seem sure it would decrease them.
In contrast, the main downside, in Tomasik’s analysis, is less controversial: that global heating is going to cause a lot of suffering by destroying or changing the habitats to which wild animals are adapted. ‘An “unfavorable climate”’, notes Katie McShane, ‘is one where there isn’t enough to eat, where what kept you safe from predators and diseases in the past no longer works, where you are increasingly watching your offspring and fellow group members suffer and die, and where the scarcity of resources leads to increased conflict, destabilizing group structures and increasing violent confrontations.’ Palmer isn’t so sure: ‘Even if some animals suffer and die, climate change might result in an overall net gain in pleasure, or preference satisfaction (for instance) in the context of sentient animals. This may be unlikely, but it’s not impossible.’ True. But even if it’s only unlikely that global heating’s effects will be good, it means that its effects on existing animals are bad in expectation.
There’s another factor which Tomasik mentions in passing: there is some chance that global heating could lead to the collapse of human civilisation—perhaps in conjunction with other factors. In some respects, this would be a good thing for non-humans—notably, it would put an end to factory farming. It would also preclude the possibility of our spreading wild animal suffering to other planets. On the flipside, however, it would also eliminate the possibility of our doing anything sizable to mitigate wild animal suffering on earth.
Now, while there may be more doubt about the upsides than about the downsides of our GHG emissions, that needn’t decide the issue if the upsides are big enough. But even if Tomasik and others are right that wild animal lives are bad on net, there’s also doubt about whether global heating will reduce the number of wild animal lives. And even if both are these premises are met, I’m not sure they’d outweigh the suffering global heating would inflict on those wild animals who will exist.
I think you have misinterpreted what my article about discounting is recommending. In contrast to some other writers, I’m not calling for discounting at the lowest possible rate. Even at a rate of 2%, catastrophic damages evaporate in cost-benefit analysis if they occur more than a couple of centuries hence, thus giving next to no weight to the distant future. However, a traditional justification for discounting is that if we didn’t, we’d be obliged to invest nearly all our income, since the number of future people could be so great. I argue for discounting damages to those who would be much better off than we are at conventional rates, but giving sizable—even if not equal—weight to damages that would be suffered by everyone else, regardless of how far into the future they exist. My approach thus has affinities with the one advocated by Geir Asheim here.
One implication is that while we’re under no obligation to make future rich people richer, we ought to be very worried about worst-case climate change scenarios, since in those humans could be poorer. Another is that since most non-humans for the foreseeable future will be worse off than we are, we shouldn’t discount their interests away.
Thanks for the follow up, Matthew! Strongly upvoted.
My best guess is also that additional GHG emissions are bad for wild animals, but it has very low resilience, so I do not want to advocate for conservationism. My views on the badness of the factory-farming of birds are much more resilient, so I am happy with people switching from poultry to beef, although I would rather have them switch to plant-based alternatives. Personally, I have been eating plant-based for 5 years.
Just flagging this link seems broken.
Sorry! It sounded so much like you were referring to Weitzman 1998 that I actually did not open the link. My bad! I have now changed “That paper says one should discount” to “One should discount”.
I do not think this is a good argument for discounting. If it turns out we should invest nearly all our income to maximise welfare, then I would support it. In reality, I think the possibility of the number of future people being so great is more than offset by the rapid decay of how much we could affect such people, such that investing nearly all our income is not advisable.
This rejects (perfect) impartiality, right? I strongly endorse expected total hedonistic utilitarianism, so I would rather maintain impartiality. At the same time, the above seems like a good heuristic for better outcomes even under fully impartial views.
Thanks, Vasco! That’s odd—the Clare Palmer link is working for me. It’s her paper ‘Does Nature Matter? The Place of the Nonhuman in the Ethics of Climate Change’—what looks like a page proof is posted on www.academia.edu.
One of the arguments in my paper is that we’re not morally obliged to do the expectably best thing of our own free will, even if we reliably can, when it would benefit others who will be much better off than we are whatever we do. So I think we disagree on that point. That said, I entirely endorse your argument about heuristics, and have argued elsewhere that even act utilitarians will do better if they reject extreme savings rates.
FYI the link doesn’t work for me either
Odd! Perhaps this one will work better.
That works!