Firstly, thanks to you and all of ALLFED for your willingness to let me prod and poke at your work in the past year.
You make some excellent points and I think they will help readers to decide where they stand on the important cruxes here.
We assign a higher probability that a nuclear conflict occurs compared to your estimates, and also assume that conditional on a nuclear conflict occurring that higher detonation totals are likely. This raises the likelihood and severity of nuclear winters versus your estimates.
For anyone wanting to get up to speed on my nuclear winter model, plus a quick intro to why nuclear cooling is so uncertain, see my just-released nuclear winter post.
Weightings of Metaculus, XPT vs individual estimates: we do place high weightings on individual’s estimates, which is not ideal. The main reason for this is that the Metaculus and XPT estimates are not calibrated to a 100+ detonation nuclear conflict involving US and/or Russia.
The Metaculus estimate still forms around 20% of the total weight. Overall, it seems credible that my final estimate (0.10%) is around a third of the Metaculus estimate (0.30%) for 100+ detonations, given that most experts I spoke to considered India/Pakistan to be one of the main threats of a 100+ detonation nuclear exchange.
The XPT estimate only forms around 2% of the total weight.
Distribution of the number of detonations in a 100+ detonation conflict. I have done my best to incorporate different sources of evidence. One expert I spoke to broadly agreed with you, Mike, and guessed that in a 100+ conflict involving US/Russia there would be 80-90% risk of over 1000 detonations. Another expert was less pessimistic and placed higher weight on the possibility of ‘moderate’ escalation involving hundreds of weapons.
I re-ran the numbers just looking at conflicts with over 1000 detonations and found that the cooling levels increase only modestly: the 75th-percentile cooling level increases from 0.66 degrees (100+ detonations) to 1.24 degrees (1000+ detonations). The initial assumption about soot volumes is far more important (see below)
Detonation-soot relationship: Yes, the results are extremely sensitive to the initial assumption about how much soot is produced in a small nuclear exchange targeting cities. When I re-ran the numbers under the more pessimistic assumption that soot levels were 10%-100% those predicted by Toon et al., 75th-percentile cooling increased from 0.66 degrees to 3 degrees.
We estimate that the expected mortality from supervolcanic eruptions (VEI 8+) would be comparable to VEI 7 eruptions, so their inclusion could increase cost effectiveness significantly.
I don’t exclude supereruptions; I estimate that the right tail of my volcanic cooling model already accounts for them.
We feel that you are selling short the importance of research in building resilience to nuclear winters in particular and ASRSs in general [...] Overall, we see research as the foundation on which you then build the policy work and other actions. Broadening and strengthening this foundation is therefore vital in allowing the work that finally effects change to occur—it isn’t an either/or.
I want to be clear that I recommend that funders prioritize policy advocacy over R&D on the margin at this point in time. I totally agree that advocacy on such an uncertain topic can only be effective if it is grounded in research, and that ALLFED’s research will very likely form the foundations of policy work in this area for years to come.
One key takeaway from my analysis is that mild and moderate scenarios form a larger proportion of the threat than the lore of nuclear winter might suggest. Resilient foods would likely have a role to play in these scenarios, but I think the calories at stake in distribution and adaptation are likely to be more pivotal.
One reason for my focus on resilient food pilot studies is that they are a possible next step for ALLFED if it were to receive a funding boost. ALLFED has been ticking along with modest but reliable core funding for some time now, and perhaps I am guilty of taking its theoretical research for granted.
Feel free to set the record straight and give some indication of the kinds of work ALLFED might be interested in accepting funding for.
Hi Mike,
Firstly, thanks to you and all of ALLFED for your willingness to let me prod and poke at your work in the past year.
You make some excellent points and I think they will help readers to decide where they stand on the important cruxes here.
For anyone wanting to get up to speed on my nuclear winter model, plus a quick intro to why nuclear cooling is so uncertain, see my just-released nuclear winter post.
Weightings of Metaculus, XPT vs individual estimates: we do place high weightings on individual’s estimates, which is not ideal. The main reason for this is that the Metaculus and XPT estimates are not calibrated to a 100+ detonation nuclear conflict involving US and/or Russia.
The Metaculus estimate still forms around 20% of the total weight. Overall, it seems credible that my final estimate (0.10%) is around a third of the Metaculus estimate (0.30%) for 100+ detonations, given that most experts I spoke to considered India/Pakistan to be one of the main threats of a 100+ detonation nuclear exchange.
The XPT estimate only forms around 2% of the total weight.
Distribution of the number of detonations in a 100+ detonation conflict. I have done my best to incorporate different sources of evidence. One expert I spoke to broadly agreed with you, Mike, and guessed that in a 100+ conflict involving US/Russia there would be 80-90% risk of over 1000 detonations. Another expert was less pessimistic and placed higher weight on the possibility of ‘moderate’ escalation involving hundreds of weapons.
I re-ran the numbers just looking at conflicts with over 1000 detonations and found that the cooling levels increase only modestly: the 75th-percentile cooling level increases from 0.66 degrees (100+ detonations) to 1.24 degrees (1000+ detonations). The initial assumption about soot volumes is far more important (see below)
Detonation-soot relationship: Yes, the results are extremely sensitive to the initial assumption about how much soot is produced in a small nuclear exchange targeting cities. When I re-ran the numbers under the more pessimistic assumption that soot levels were 10%-100% those predicted by Toon et al., 75th-percentile cooling increased from 0.66 degrees to 3 degrees.
I don’t exclude supereruptions; I estimate that the right tail of my volcanic cooling model already accounts for them.
I want to be clear that I recommend that funders prioritize policy advocacy over R&D on the margin at this point in time. I totally agree that advocacy on such an uncertain topic can only be effective if it is grounded in research, and that ALLFED’s research will very likely form the foundations of policy work in this area for years to come.
One key takeaway from my analysis is that mild and moderate scenarios form a larger proportion of the threat than the lore of nuclear winter might suggest. Resilient foods would likely have a role to play in these scenarios, but I think the calories at stake in distribution and adaptation are likely to be more pivotal.
One reason for my focus on resilient food pilot studies is that they are a possible next step for ALLFED if it were to receive a funding boost. ALLFED has been ticking along with modest but reliable core funding for some time now, and perhaps I am guilty of taking its theoretical research for granted.
Feel free to set the record straight and give some indication of the kinds of work ALLFED might be interested in accepting funding for.