I research a wide variety of issues relevant to global health and development. I also consult as a researcher for GiveWell. I'm always happy to chat - if you think we have similar interests and would like to talk, send me a calendar invite at karthikt@berkeley.edu!
Interestingly, metaculus forecast on this was off by an order of magnitude (15% vs 300-400%). Only three people forecasted, so I wouldn't read too much into it, but it is a wide gap.
The CE of redirecting money is simply (dollars raised per dollar spent) * (difference in CE between your use of the money vs counterfactual use). So if GD raises $10 from climate mitigation for every $1 it spent, and that money would have otherwise been neutral, then that's a cost-effectiveness of 10x in GiveWell units.
There's nothing complicated about estimating the value of leverage. The problem is actually doing leverage. Everyone is trying to leverage everyone else. When there is money to be had, there are a bunch of organizations trying to influence how it is spent. Melinda French Gates is likely deluged with organizations trying to pitch her for money. The CEAP shutdown post you mentioned puts it perfectly:
The core thesis of our charity fell prey to the 1% fallacy. Within any country, much of the development budget is fixed and difficult to move. For example, most countries will have made binding commitments spanning several years to fund various projects and institutions. Another large chunk is going to be spent on political priorities (funding Ukraine, taking in refugees, etc.) which is also difficult for an outsider to influence.
What is left is fought over by hundreds, if not thousands of NGOs all looking for funding. I can’t think of any other government budget with as many entities fighting over as small a budget. The NGOs which survive in this space, are those which were best at getting grants. Like other industries dependent on government subsidies, they fight tooth and nail to ensure those subsidies stay put.
This doesn't mean that leverage is impossible. It just means that leverage opportunities tend to be specific and limited. We have to take them on opportunistically, rather than making leverage a theory of impact.
During the animal welfare vs global health debate week, I was very reluctant to make a post or argument in favor of global health, the cause I work in and that animates me. Here are some reflections on why, that may or may not apply to other people:
I'm deliberately focusing on emotional/psychological inhibitions as opposed to analytical doubts I have about animal welfare. I do have some analytical doubts, but I think of them as secondary to the personal relationship I have with GHD.
Cash transfers are not targeted (i.e. lots of households receive transfers that don't have young children) and are very expensive relative to other ways to avert child deaths ($1000 vs a few dollars for a bednet). The latter varies over more orders of magnitude than child mortality effects, so it dominates the calculation.