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Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: [4] Climatic consequences of regional nuclear conflicts (Robock et al., 2007), published by Will Aldred on July 15, 2022 on The Effective Altruism Forum. Will's quick summary and hot takes: I've heard this Robock et al. paper get cited a lot, including twice at the SERI Conference '22. This is unfortunate, because while the paper makes important claims relating to nuclear x-risk, these claims are probably wrong. To clarify, the paper being cited at all is not unfortunate, and the authors' writing of this paper started an important debate. For this, I commend them. However, I've almost always heard the paper's conclusion cited in isolation, without acknowledgement of the subsequent debate and counterconclusion. More on this below. Robock et al.'s, paper, published in 2007, concluded that there'd be significant global cooling effects resulting from a regional nuclear war, e.g., between India and Pakistan. "Significant global cooling effects" as Robock et al. refer to it means nuclear autumn bordering on nuclear winter. Reisner et al., a separate group from Los Alamos National Lab, in 2018 published a paper titled "Climate Impact of a Regional Nuclear Weapons Exchange: An Improved Assessment Based On Detailed Source Calculations." Given that the original Robock et al. paper was titled "Climate Impact of a Regional Nuclear Weapons Exchange," this was a spicy move. The Reisner et al. paper effectively reruns the modelling done by Robock et al., but with some different and arguably more sophisticated starting assumptions. Reisner et al. conclude that regional nuclear war would result in negligible global cooling. Robock et al. responded to Reisner et al.'s critique, and Reisner et al. responded to the response. Both groups make some valid arguments, but overall Reisner et al. are closer to the truth, according to me (or at least, the version of me at the time of writing). To explain the heart of the disagreement, I'll first lay out my 3-step model of where disagreement occurs when talking about nuclear winter effects: How much soot gets up into the stratosphere? Given x quantity of soot in the stratosphere, how much cooling occurs? Given y amount of cooling, i) how much crop failure? ii) how much human starvation? It turns out that 2 is pretty uncontroversial, and 1 and 3 are where disagreements lie. I'll return to 3 in other posts (e.g., I'll discuss Helfand, 2013 and Jagermeyr, 2020). 1 is what the Robock and Reisner groups are disagreeing over. Reisner et al. write: While our thorough simulations of the firestorm produce about 3.7 × 109 kg of black carbon, we find that the vast majority of the black carbon never reaches an altitude above weather systems (approximately 12 km). Therefore, our Earth system model simulations conducted with model-informed atmospheric distributions of black carbon produce significantly lower global climatic impacts than assessed in prior studies, as the carbon at lower altitudes is more quickly removed from the atmosphere. In addition, our model ensembles indicate that statistically significant effects on global surface temperatures are limited to the first 5 years and are much smaller in magnitude than those shown in earlier works. None of the simulations produced a nuclear winter effect. Thanks for listening. To help us out with The Nonlinear Library or to learn more, please visit nonlinear.org.