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Cost Effectiveness of Climate Change Interventions

No worries! I'm glad you found the paper useful and interesting!

The mortality cost of carbon is just the number of excess deaths from temperature-related mortality in units of excess deaths from emitting one metric ton of CO_2. So it's just excess deaths and nothing else. The social cost of carbon is the full monetized value of all climate impacts from emitting one ton of CO_2, which includes the monetized value of those excess deaths in addition to other sources of climate damages. You can see that before the model accounted for temperature-related mortality, the social cost of carbon was $37, but after accounting for temperature-related mortality, it is $258. However, note my caveat from the conclusion: "It is important to note that recent literature has identified other shortcomings in the DICE model including other issues with the climate-economy damage function and the climate module. Besides adding the effect of climate change on mortality and subsequent feedbacks, DICE-EMR takes the rest of the DICE model as given without updating other factors."

It's hard for me to determine how much the different simplifying assumptions from your back-of-the-envelope formula are affecting your estimate. The linearity assumption is certainly causing a big difference because the system is highly convex. Also, the DICE-EMR model has the DICE climate model built into it that can show the climatic effect of changes in emissions. I'm not sure how much error you're introducing with the back-of-the envelope climate assumptions, but that could also be an issue.

All this to say, if estimating the marginal impact (either the mortality cost of carbon or the full social cost of carbon) were as simple as a back-of-the envelope calculation, then there wouldn't be a need to give William Nordhaus the Nobel Prize for his work on the original DICE model (the first one for environmental economics), nor for me to do this work. I think Louis Dixon's original post is basically all you need to do for this exercise (at least for leveraging my paper's results). Or as @jh suggested above, a $1/ton estimate just gets you to $4.4K per life saved using my paper's results.

Also, see this one quote from the end of the paper: "Separate from policy, the MCC and SCC can be useful in informing the decision-making of individuals, households, companies, charities, and other organizations in determining the social impact of the emissions generated by their activities. The emissions contributions of these groups are usually marginal relative to the aggregate emissions of the world economy from the industrial revolution through the twenty-first century. Therefore, the social impact of changes in their activities that either reduce or increase emissions should be quantified using estimates of marginal impacts: i.e. the SCC and the MCC." 

Cost Effectiveness of Climate Change Interventions

Thank you for this post on a very important topic! And thank you for the kind words on my Mortality Cost of Carbon paper. 

I think that, at least from the perspective of using my paper, the analysis is actually much simpler than what you do above.  Instead of using the 83 million cumulative 2020-2100 excess deaths, use the mortality cost of carbon itself: i.e. the number of lives saved per ton of carbon dioxide reduced, which is provided by the paper. So instead of the equation you show above, the equation now becomes:

Marginal Cost Per Life Saved = (Marginal Cost Per Ton CO_2 reduced)/(The Mortality Cost of Carbon)

@Louis_Dixon   performed this analysis before in a really nice post Does using the mortality cost of carbon make reducing emissions comparable with health interventions? - EA Forum (effectivealtruism.org) and found that using carbon dioxide reduction estimates from a Founder's Pledge report:

  • Future pessimistic - $5.50 per tonne, so $23,400 to avert 4,255 tons*
  • Future realistic - $0.29 per tonne, so $1,234 to avert 4,255 tons
  • Future optimistic - $0.03 per tonnes, so $127 to avert 4,255 tons

The issue with your original equation above is that you are implicitly assuming linearity, i.e. assuming that the marginal cost of saving a life from marginally reducing emissions is equivalent to the average cost of saving a life if we were to reduce emissions all the way to zero. However, one of the findings of the Mortality Cost of Carbon paper is that the system is actually nonlinear and highly convex, so the number of lives saved from marginally reducing emissions is actually much greater than the average number of lives saved that you would get per ton if you were to reduce all the way to zero (see figure 4). This is all a fancy way to say that there are diminishing marginal returns in terms of saving lives from reducing carbon dioxide on a planetary scale. So to determine the marginal impact of reducing emissions, use the marginal estimates provided by the paper (the mortality cost of carbon).

And of course, as you mention above, the mortality cost of carbon is just the projected number of excess deaths from 2020-2100 caused by marginal emissions due to temperature-related mortality - i.e. the net effect of more hot days (bad for mortality) and fewer cold days (good for mortality). It leaves out potentially important climate-mortality pathways such as the effect of climate change on infectious disease, civil and interstate war, food supply, flooding, as well as the co-benefit from less air pollution. Despite these limitations, Louis was still finding that these projections were cost-competitive with Givewell's top recommendations.


*Note that Louis was using the 2020 Working Paper version of the Mortality Cost of Carbon, which included all mortality sources from the 2014 WHO paper (one of three papers used to construct the mortality damage function, which Andrew also mentions in the post), whereas the 2021 published version of the paper in Nature Communications used just the temperature-related mortality estimates from the 2014 WHO report. This ends up leading to a slight difference in the mortality cost of carbon estimate, from 1/4255 in the working paper version to 1/4434 in the published paper version. Recalculating Louis's analysis with the published paper version numbers yields:

  • Future pessimistic - $5.50 per tonne, so $24,387 to avert 4,434 tons*
  • Future realistic - $0.29 per tonne, so $1,286 to avert 4,434 tons
  • Future optimistic - $0.03 per tonnes, so $133 to avert 4,434 tons
The NPT: Learning from a Longtermist Success [Links!]

Yes, I think it is. There is a literature on whether nuclear assistance  and technology sharing for peaceful uses tends to promote or hinder nuclear proliferation, that I mention and cite a bit in my second CSIS piece.

The NPT: Learning from a Longtermist Success [Links!]
  1.  One piece of info related to the NPT that might be helpful: The NPT does contain an article (article VI) in which the the P5  (the 5 current permanent members of the UN Security Council, who at the time the NPT was made were the only countries who had successfully tested nuclear weapons) as well as all of the parties agree to participate in good-faith negotiations to pursue nuclear disarmament, but it does not specify a time-table and the language is deliberately vague. I think the NPT has done a good job of doing what its main goal is and what its name implies: limiting nuclear proliferation. It has clearly not been able to get existing nuclear powers to get rid of all of their nuclear weapons (although it's hard to know if the NPT has not played a significant role in reducing the arsenals of the nuclear powers relative to a counterfactual world in which there was no NPT... perhaps in a counterfactual world without the NPT, the US and USSR would not feel compelled to engage in the SALT and START negotiations without officially committing in Article VI of the NPT). Luisa has done a lot more thinking about the Nuclear Ban treaty, so I'll defer to her on that. 
  2. Jeffrey Ohl is going to look into this question as part of a summer project for the Stanford Existential Risk Initiative, and I'll be mentoring him. We literally just started talking about the project last week, so more to come on that! For now, I'll say the characteristics of the technology itself that you are trying to regulate (e.g. fissile material vs.  inputs to the creating of AGI for instance) is very important in terms of how a successful treaty could be constructed. This aspect is important in terms of the mechanisms that must be put in place to verify compliance with the treaty. I co-wrote an article with Chris Bakerlee on engineered pathogens for Vox a few years ago that discusses, among other things, some of the challenges around regulating biotechnology that make verifying compliance with the Biological Weapons Convention difficult https://www.vox.com/future-perfect/2018/12/6/18127430/superbugs-biotech-pathogens-biorisk-pandemic
  3. What time range are you looking at when it comes to forecasts, and what sort of things do you have in mind? I recall when I read Superforecasting a few years ago that forecasts aren't particularly reliable beyond a few years even for Superforecasters (though correct me if I'm wrong/maybe views on that are different now than they were then?). These treaties operate on pretty long time-scales... e.g. the NPT was conceived of in the mid 1960s, it was signed in 1968, it went into force in 1970, and then countries joined over the course of a few decades. https://en.wikipedia.org/wiki/List_of_parties_to_the_Treaty_on_the_Non-Proliferation_of_Nuclear_Weapons
The NPT: Learning from a Longtermist Success [Links!]

One other reason why I think that understanding the NPT is important for longtermists: As the world decarbonizes to address climate change (my other big area of research), nuclear electricity generation may increase substantially into more countries, and in particular to countries with lower levels of development/technology. It's crucial to know if the existing nonproliferation regime can ensure that this doesn't cause proliferation, and what sorts of investments must be made to ensure that nonproliferation regime continues to work.

N-95 For All: A Covid-19 Policy Proposal

This is a really good point!

I think you're right that the magnitude of the benefit from the program depends heavily on how many people end up choosing to use the mask, especially in situations where they are more likely to contract the disease. Individuals will ultimately make a personal decision based on trade-offs between the probability of contracting the virus, comfort, convenience, and even fashion.

I also think there is significant heterogeneity in terms of how people weigh these factors. I do think that there are a significant number of people who, net of these factors, would decide that the benefits of wearing a medical-grade respirator in situations where they are more likely to contract the virus outweighs the costs. These could be seniors, people with preexisting conditions,  people who don't find the respirator uncomfortable, or people who are just risk averse. 

I also think that there are currently significant numbers of people who would like to wear medical-grade respirators, but who are not currently able to get them. I have friends that are teachers that are required to teach in person that want a medical-grade respirator, but are not able to get one. As I noted above, there is still a shortage of respirators even for frontline medical workers (see https://www.washingtonpost.com/business/scarcity-of-raw-material-still-squeezes-n95-mask-makers/2020/09/10/94586834-f31e-11ea-8025-5d3489768ac8_story.html). I think there are probably enough people in this category, that you could make some dent in the infection rate with this policy, though how much depends on people's behavior.

Also, one of the general takeaways is that, even if the benefits end up being modest (e.g. you reduce the infection rate, but not below 1 in all areas), the relative cost is so cheap that I think it's worth it to give it a shot.


A few other points:

-As part of the program, it would be great to do randomized control trials with different types of respirators (e.g. different designs that meet the N-95 standard, enhanced N-99 or N-100 designs). There may be some sort of trade-off between comfort and protection (granted that the N-95 threshold is met), and perhaps going more on the side of comfort is optimal because the benefit from higher compliance outweighs the slightly lower protection. There may also be an N-95 design that is already produced (or gets produced for the program) that is just more comfortable and gets higher compliance, and we'd be able to figure that out. That face shield you mentioned is really cool! You could also pilot something like that as part of this program, and perhaps that wins out. 

-Along these lines, I also considered adding another point, which would be creating a program called  the "N-95 for all Studio," where fashion designers or people like that could add designs to the respirators to make them look cool. You could imagine charging someone $2 or something to get the "New York Yankees N-95" or the "Tom Ford N-95" or whatever. 

-Also as winter comes in the Northern Hemisphere and as more activity moves inside and the ability to ventilate rooms goes down, there will likely  be more spaces with a higher concentration of aerosols. The benefit of wearing a respirator vs. cloth mask or surgical mask goes up in this situation, so this would affect people's behavior.

-I'd also emphasize the benefits of this policy for preparing for future pandemics. It so happens that SARS-COV-2 has a case fatality rate ~1%, and this is quite heterogeneous depending on your age and existing health. If there is a respiratory-transmitted pandemic that has a 30% case fatality rate, then the benefits of wearing a respirator will be way higher versus the costs from inconvenience, discomfort, etc.

N-95 For All: A Covid-19 Policy Proposal

What I had in mind with this policy was that the government would contract directly with producers (using the defense production act where necessary) to procure enough N-95 respirators for everyone in the country, and the government would then distribute them to everyone. There would be some agreed upon price of procurement between the government and manufacturers that would be negotiated at the start of the process. If manufacturers want to produce more respirators than what they contracted for, they are welcome to do that and to sell it at a price they choose. 

What I mean by cannot buy is that N-95s are unavailable to nearly all people who may want to purchase them https://twitter.com/davidrliu/status/1319980228765274112?s=20. I've looked online throughout the pandemic, and they are usually unavailable for purchase. Sometimes, you can add them to your cart, but then you can't check out because you get a warning that they are being prioritized for frontline workers (that screenshot above is me doing exactly that).  Sometimes, you can buy more heavy duty P100 respirators that have traditionally been used for doing something like spray painting, but a lot of people prefer not to wear those regularly because they are more bulky. 

N-95 For All: A Covid-19 Policy Proposal

Thanks, John! I really like your distinction between the type (1) and type (2) "pernicious moral hazard."

Yes I agree that the moral hazard I mention here would not be large enough to outweigh the benefits of the policy, putting it in the category of (1). My goal in that "potential issues" section was to think about the universe of potential issues that people could raise about the policy and address them. As you can tell, I don't currently think any of the issues are significant enough to make the policy not worth it. 

Avoiding Munich's Mistakes: Advice for CEA and Local Groups

By the title, I thought this was going to be a discussion of the dangers of appeasing genocidal dictators (e.g. https://www.ynetnews.com/articles/0,7340,L-3476200,00.html) ... clearly I was wrong!

Does using the mortality cost of carbon make reducing emissions comparable with health interventions?

FYI, I gave a presentation on my Mortality Cost of Carbon paper at the UCLA Climate Adaptation conference two days ago, available here: https://event.on24.com/wcc/r/2688287/118B1E2E57B33A902FDE6CE95202DB34 This is a brief (~20 minutes) less technical overview of the paper. My presentation starts at 53:20.

Also, the other two speakers on the panel (Tamma Carleton and Ishan Nath) were both authors on the Climate Impact Lab paper that Louis had posted about earlier: https://forum.effectivealtruism.org/posts/PATHShQoxQLHoZ7rE/linkpost-global-death-rate-from-rising-temperatures-to

My Mortality Cost of Carbon working paper is here: https://ceep.columbia.edu/sites/default/files/content/papers/n11.pdf

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