Whether a nuclear war could become an existential catastrophe is highly uncertain — but it remains a possibility. What’s more, we think it’s unclear whether the world after a nuclear conflict would retain what resilience we currently have to other existential risks, such as potentially catastrophic pandemics or risks from currently unknown future technology. If we’re hit with a pandemic in the middle of a nuclear winter, it might be the complete end of the human story.
I think nuclear war becoming an existential catastrophe is an extremely remote possibility:
I estimated an annual extinction risk from nuclear war of 5.93*10^-12.
I believe the chance of an existential catastrophe conditional on a nuclear war causing extinction is quite low.
The most severe nuclear winters are way less severe than the above event. Xia 2022 considers a maximum soot injection into the stratosphere of 150 Tg. I believe this is pessimistic, but it is still only 1 % of the 15 kTg estimated by Bardeen 2017for the above event.
I would say accounting for indirect effects should not change much your overall assessment of the pressingness of nuclear risk:
In 80,000 Hours’ nuclear war profile, you say “the indirect existential risk [from nuclear war] seems around 10 times higher [than the direct one]”. So, if you agreed (I am not saying you do!) with my points above suggesting direct existential risk from nuclear war is astronomically low, then the indirect one would also be astronomically low.
My sense is that 80,000 Hours puts significant weight on Toby Ord’s views, and he commented the following yesterday (I am quoting the 2 paragraphs of his comment below):
“For what it’s worth, my working assumption [in The Precipice] for many risks (e.g. nuclear, supervolcanic eruption) was that their contribution to existential risk via ‘direct’ extinction was of a similar level to their contribution via civilisation collapse. e.g. that a civilisation collapse event was something like 10 times as likely, but that there was also a 90% chance of recovery. So in total, the consideration of non-direct pathways roughly doubled my estimates for a number of risks”.
“One thing I didn’t do was to include their roles as risk factors. e.g. the effect that being on the brink of nuclear war has on overall existential risk even if the nuclear war doesn’t occur”.
Thanks Vasco! I’m working on a longer article on exactly this question (how pressing is nuclear risk). I’m not quite sure what I’ll end up concluding yet, but your work is a really helpful input.
Thanks for the update, Ben!
I think nuclear war becoming an existential catastrophe is an extremely remote possibility:
I estimated an annual extinction risk from nuclear war of 5.93*10^-12.
I believe the chance of an existential catastrophe conditional on a nuclear war causing extinction is quite low.
I calculated there would only be a 0.0513 % chance of a repetition of the last mass extinction 66 M years ago, the Cretaceous–Paleogene extinction event, being existential.
The most severe nuclear winters are way less severe than the above event. Xia 2022 considers a maximum soot injection into the stratosphere of 150 Tg. I believe this is pessimistic, but it is still only 1 % of the 15 kTg estimated by Bardeen 2017 for the above event.
I would say accounting for indirect effects should not change much your overall assessment of the pressingness of nuclear risk:
In 80,000 Hours’ nuclear war profile, you say “the indirect existential risk [from nuclear war] seems around 10 times higher [than the direct one]”. So, if you agreed (I am not saying you do!) with my points above suggesting direct existential risk from nuclear war is astronomically low, then the indirect one would also be astronomically low.
My sense is that 80,000 Hours puts significant weight on Toby Ord’s views, and he commented the following yesterday (I am quoting the 2 paragraphs of his comment below):
“For what it’s worth, my working assumption [in The Precipice] for many risks (e.g. nuclear, supervolcanic eruption) was that their contribution to existential risk via ‘direct’ extinction was of a similar level to their contribution via civilisation collapse. e.g. that a civilisation collapse event was something like 10 times as likely, but that there was also a 90% chance of recovery. So in total, the consideration of non-direct pathways roughly doubled my estimates for a number of risks”.
“One thing I didn’t do was to include their roles as risk factors. e.g. the effect that being on the brink of nuclear war has on overall existential risk even if the nuclear war doesn’t occur”.
Thanks Vasco! I’m working on a longer article on exactly this question (how pressing is nuclear risk). I’m not quite sure what I’ll end up concluding yet, but your work is a really helpful input.