The DICE-2023 model of the Social Cost of Carbon has revised up the harms of climate change, and down the costs. At what point does climate change become cost competitive with global poverty charities?
I think the estimated harms have gone up because they changed their modeling, and the estimated cost of carbon removal (and prevention) has gone down because of technology.
I think marginal climate interventions are in the conversation for being competitive on a global health and wellbeing basis. By that I mean ignoring the chance of existential risk from climate change, marginal climate interventions are in the conversation for being competitive just based on the expected impacts of climate change, which will be concentrated on the world's poorest people. This is provided that you can reduce marginal emissions on the order of ~$1 per ton (which I know some folks have said is a reasonable estimate for targeted marginal emissions reductions... my expertise is much more on the climate impacts side so I'll keep that as given for now).
Note that DICE-2023 has multiple aspects that cause it to understate the benefits of emissions reductions compared to, e.g. OP's Global Health and Wellbeing Framework:
-DICE counts a dollar to the poorest people on the planet the same as a dollar to a billionaire. Whereas if you are interested in determining the impact on wellbeing, you'd want to account for diminishing marginal utility -- i.e. a dollar of climate damages is much more harmful to a very poor person than to a very rich person. The way to do this in benefit-cost analysis is called distributional or welfare weighting, which is, e.g., what Open Philanthropy's Global Health and Wellbeing Framework does. Distributional weighting was just sanctioned by the US Government for use in benefit-cost analysis (provided that the new draft guidelines are not altered in the review and public comment process), and it is already used in the UK and Germany. Because climate change is projected to hurt the global poor much more than the rich, the SCC goes way up when you do distributional weighting.
-DICE continues to ignore the impact of climate change on temperature-related mortality. The latest IAMs that were used in the November 2022 EPA SC-GHG update suggest that ~50-80% of the SCC comes from temperature-related mortality. And this is when lives are valued proportionally to their income so that, e.g., 50 Congolese deaths are counted the same as 1 Belgian death. If you valued lives equally, this percentage would be much higher. The mortality damage functions in those studies are similar to the mortality damage function from my 2021 Mortality Cost of Carbon article, which finds that reducing 4,434 tons in a higher emissions scenario saves one life over the next 80 years and 9,318 tons in a lower emissions scenario (net zero by 2050). I.e. if you can remove a ton of carbon dioxide on the margin for $1, you would save one life in expectation for $4,434 in the high emissions scenario and $9,318 in the low emissions scenario. And this is only the benefit of reducing emissions on temperature-related mortality and ignores all of the other benefits from reducing emissions. Some of those benefits are captured in Social Cost of Carbon estimates (e.g. the projected impact of climate on staple crops is included in the GIVE and DSCIM models, as is sea level rise coastal impacts, and the impact on energy use), but many impacts that we have reason to believe could be large are not included (e.g. the impact of climate change on ocean acidification, biodiversity, conflict, and much more).
So these various factors I think put marginal climate interventions into the discussion as being cost-effective from a global health and wellbeing perspective.
