I agree that the sign of the effect is unclear in addition to the magnitude, that is, nuclear winter + termination is “better” at first than nuclear winter alone, but “worse” afterwards if it is impossible to restart; that of course is all contingent on how bad the nuclear winter is, how much cooling is being offset, and your beliefs about how the use of SRM does or doesn’t affect mitigation (that is, the circumstances in which termination materially affects outcomes are those in which SRM is being used to offset significant warming – so from a risk perspective, if the counterfactual is that much warmer world, or the counterfactual a world that had more mitigation, is essential).
I agree that as researchers we should try to inform decisions, and hence risks, and be responsive to stakeholder concerns. In this case, I think the *much* bigger influence of SRM on nuclear winter comes from whether it increases or decreases the risks of nuclear war, and what we can do in terms of governance to affect that… From: Gideon Futerman <ggfuter...@gmail.com> Sent: Wednesday, July 27, 2022 6:10 PM To: Douglas MacMartin <dgm...@cornell.edu> Cc: gdebrou...@gmail.com; Daniele Visioni <daniele.visi...@gmail.com>; geoengineering <geoengineering@googlegroups.com> Subject: Re: [geo] Nuclear Winter and SRM (including termination shock) I think this is going to get into more general philosophy/ethics around Existential Risks, Longtermism and Global Catastrophic Risks, which whilst interesting and useful, probably a bit orthogonal to what people are turning to the geoengineering google group for. But basically, a difference between 6 billion and say 6.1 billion or 6.5 billion is firstly important from the perspective of deaths: that's still 100 million people. Secondly, climatic effects, excess deaths on top of the nuclear winter (or reduced severity!) etc are potentially relevant for whether it will "only" kill 6 billion and whether it will lead to irrecoverable (not merely awful) societal collapse, which from various longtermist perspectives is very bad. Given how hard it would be to recover anyway, a "double catastrophe" could make recovery much harder distinguish between a Global Catastrophic Risk and an existential risk, which from various philosophical viewpoints is very important. Thus, such a question ie whether SRM might increase/decrease the likelihood of a global catastrophic risk being converted to an existential risk (due to this Latent Risk of termination shock we have been discussing) is of serious interest to many people, including potentially major funders who are potentially interested in investing in SRM research. In that sense, this impacts some potentially very important decisions for the future of our field, and the distinction between 6 billion and say 6.5 billion, or even if it just makes societal recovery 10% less likely to happen, it may be absolutely vital. I am happy to explain this in more depth if people need, although what I was really wanting to ask the list for was fundamentally a question of physical science to try and answer this application. Even if none of this has convinced you of the moral importance of it, the question I was asking was fundamentally a physical one, responding to a scientific assumption in Baum et al 2013 that I thought seemed potentially unsound (that under nuclear war termination shock would lead to a double catastrophe and not a slight softening of the first catastrophe). Given that paper is one of only a handful papers published in this intersection between SRM and Global Catastrophic Risk studies, such a claim is, even from a physical/empirical rather than moral viewpoint, important to test. Hence why I have posed this question. On Wed, 27 Jul 2022 at 19:59, Douglas MacMartin <dgm...@cornell.edu<mailto:dgm...@cornell.edu>> wrote: All of the above, with qualifiers… yes the climatic response would be different, but personally I think 6B dead is so bad that whether it’s 6.01 or 6.1 or 6.5 isn’t something that I feel matters particularly (nor do I think it is particularly answerable). What decisions would depend on the answer to that question? From: Gideon Futerman <ggfuter...@gmail.com<mailto:ggfuter...@gmail.com>> Sent: Wednesday, July 27, 2022 1:31 PM To: Douglas MacMartin <dgm...@cornell.edu<mailto:dgm...@cornell.edu>> Cc: gdebrou...@gmail.com<mailto:gdebrou...@gmail.com>; Daniele Visioni <daniele.visi...@gmail.com<mailto:daniele.visi...@gmail.com>>; geoengineering <geoengineering@googlegroups.com<mailto:geoengineering@googlegroups.com>> Subject: Re: [geo] Nuclear Winter and SRM (including termination shock) Hi Doug, Apologies for misinterpreting. Its a statement like this that I have been looking for. When you suggest it isn't appreciably worse, is that a suggestion that either: - The death toll/ the ability for society to recover would be no different given the double catastrophe than the single catastrophe - The climatic response to the double catastrophe is no different than the single catastrophe - The difference in death toll may be, say (and these are made up numbers) 6 billion vs 6.01 billion Thank you so much for the clarification Best Gideon On Wed, 27 Jul 2022 at 17:58, Douglas MacMartin <dgm...@cornell.edu<mailto:dgm...@cornell.edu>> wrote: Of course there are more minor conflicts possible with less severe outcomes… though if it’s a regional war that doesn’t itself end civilization, I don’t see why one couldn’t restart SRM in a year or two if desired. Gideon, you write: “I understand why there is aversion to me exploring such risks;” I think you misunderstand everyone’s response here. It isn’t an aversion to exploring them, nor a belief that we don’t need to look at extreme but less likely scenarios, but rather, that this specific risk doesn’t seem to many of us like there’s anything that needs to be explored. That is, my view, and I think others, is that any nuclear war severe enough to result in losing the ability to even restart SRM is so severe that the nuclear war + termination isn’t appreciably worse than the nuclear war itself. I 100% agree with the need to think through low probability but high impact possibilities. d From: geoengineering@googlegroups.com<mailto:geoengineering@googlegroups.com> <geoengineering@googlegroups.com<mailto:geoengineering@googlegroups.com>> On Behalf Of Gilles de Brouwer Sent: Tuesday, July 26, 2022 11:11 PM To: ggfuter...@gmail.com<mailto:ggfuter...@gmail.com> Cc: Daniele Visioni <daniele.visi...@gmail.com<mailto:daniele.visi...@gmail.com>>; geoengineering <geoengineering@googlegroups.com<mailto:geoengineering@googlegroups.com>> Subject: Re: [geo] Nuclear Winter and SRM (including termination shock) FYI Updated nuclear winter analysis is so much worse than SAI that it's pointless to consider. Nuclear winter revisited with a modern climate model and current nuclear arsenals: Still catastrophic consequences Alan Robock,1 Luke Oman,1,2 and Georgiy L. Stenchikov1 Received 8 November 2006; revised 2 April 2007; accepted 27 April 2007; published 6 July 2007 https://climate.envsci.rutgers.edu/pdf/RobockNW2006JD008235.pdf Gilles de Brouwer On Tue, Jul 26, 2022 at 5:50 PM Gideon Futerman <ggfuter...@gmail.com<mailto:ggfuter...@gmail.com>> wrote: Apologies, you are correct, I was using the ECS values from AR5 and forgot it had reduced with AR6. I was also getting my range vs values mixed up. Nonetheless, a similar point still broadly stands- the ipcc suggests with only medium confidence that it is "very likely" that ECS is between 2K and 5K (not 6K as I had previously stated), putting a warming of anything above 5K therefore at between 0-5% probability with medium confidence. Whilst I appreciate the desire to focus on the median ECS, I think it is nonetheless important to consider the more extreme, fat tailed risks. Not because these will happen or are likely to happen, but because in general such worse case scenario, low probability high impact scenarios are neglected. This is the same reason I care about SRM in concert with a nuclear war. Not because I want to overplay how important SRM is under such a scenario, but merely want to explore the worse case scenarios. I don’t think (certainly hope not) that any of the scenarios the RESILIENCER Project explores are likely, certainly none are the median scenarios. Rather, they are those scenarios in the fat tails of the possible risks. I understand why there is aversion to me exploring such risks; I would hate people to think that I am claiming the research community at large should start focusing on such risks (which would be foolish). Nonetheless, it seems odd to not at least some degree look at these more extreme, much less likely, scenarios. On Tue, 26 Jul 2022, 22:33 Daniele Visioni, <daniele.visi...@gmail.com<mailto:daniele.visi...@gmail.com>> wrote: Dear Gideon, not to pile on but I feel like this should be corrected: none of the most current IPCC projections say that 550ppm have a 10% chance of leaving us with 6K of warming. Even the most high sensitivity models in CMIP6 only show a ECS of, at most, 5 per doubling of CO₂ (so 560), but the best estimate is still around 3K given a whole range of approaches to estimate it. For more relevant IPCC scenarios during this century, given transient sensitivity and more, scenarios that lead to 550ppm (considering also other GHG, LUC, aerosols) like SSP2-4.5 have a median warming of a bit less than 3K. How can surely say the IPCC is wrong and climate models are wrong, of course. (Ça vas sans dire, I’m not trying to downplay climate change! But being precise helps having better discussions :) ) On 26 Jul 2022, at 17:20, Gideon Futerman <ggfuter...@gmail.com<mailto:ggfuter...@gmail.com>> wrote: Dear Dr Robock, Whilst I would admit that 3K of cooling by SRM is unlikely, it is certainly not out of the range of possibility. Given CO2 concentrations of 550PPM have a 10% chance of leaving us with 6K of warming (and that certainly doesn't seem to be an unreasonable amount of emissions given mitigation trajectories), it certainly doesn't seem like there is a less than 10% probability of a given deployment scheme being 3K of forcing. Secondly, why care about this if there is a nuclear war. Maybe you are correct, and there is no worry. But if you care about post-nuclear war societal recovery, it may be important to know whether SRM-driven termination shock makes that more or less likely, or is entirely negligible. Of course, the primary worry here is avoid the initial catastrophe (nuclear war). Nonetheless, the question of whether SRM termination shock under nuclear war has any effect (even if only 10% of the magnitude of the effects of the nuclear war) is significant. I am trying to look at low probability, heavy tailed risks of SRM, including how it interacts with other risks. This is why I want to look at the (relatively unlikely) scenario which I have laid out. And apologies for the spelling mistake, spelling is certainly not my strong suit! Kind Regards Gideon Futerman He/Him www.resiliencer.org<http://www.resiliencer.org> On Tuesday, 26 July 2022 at 16:05:48 UTC+1 Alan Robock wrote: Dear Gideon, It is spelled "negligible." And nobody is suggesting enough SAI to produce 3K cooling, because that means there has been no mitigation. A nuclear war could kill billions of people from starvation, and would collapse civilization, surely reducing greenhouse gas emissions. Why would you even worry about global warming and geoengineering then? That's why I say your are comparing two things that are of completely different scales. Alan Robock Alan Robock, Distinguished Professor Department of Environmental Sciences Phone: +1-848-932-5751<tel:(848)%20932-5751> Rutgers University E-mail: rob...@envsci.rutgers.edu<mailto:rob...@envsci.rutgers.edu> 14 College Farm Road http://people.envsci.rutgers.edu/robock New Brunswick, NJ 08901-8551 ☮ https://twitter.com/AlanRobock On 7/26/2022 10:59 AM, Gideon Futerman wrote: Dear Alan Robock, When you say overwhelm, is the suggestion here that the increase in radiative forcing from the termination of aerosol injection would be entirely negligable compared to the nuclear winter scenario? If SAI were masking 3K of warming, and you got a nuclear winter driven cooling of say 7K, surely the impact of the termination of SAI would not be negligable, even if it would be significantly less than the cooling of nuclear winter (ie you still get a nuclear winter)? I am trying to work out if the "double catastrophe" as Baum calls it actually applies in the nuclear winter scenario. So the question of whether the removal of the contribution of SAI to radiative forcing (by termination) makes the nuclear winter (and the resulting warming afterwards) worse, less bad or is entirely negligable is important. Moreover might sunlight removal effects be important in the short term, particularly if it were a relatively high SAI radiative forcing and (relatively) minor nuclear winter (say about 6K of cooling)? Given up to 50% of sulfate aerosols remain in the stratosphere up to 8 months after termination, would the added impact of the sulfate aerosols on top of the significantly more soot aerosols have an effect of sunlight available for photosynthesis, so increase impact on food production in the early days of the nuclear winter? Or would this simply be negligable in the face of the radiation reduction from even a relatively minor nuclear winter? Kind Regards Gideon On Tuesday, 26 July 2022 at 15:20:44 UTC+1 Alan Robock wrote: Dear Gideon, A nuclear war would be orders of magnitude worse than any impacts of SAI or termination. Soot from fires ignited by nuclear attacks on cities and industrial areas would last for many years, and would overwhelm any impacts from shorter lived sulfate aerosols. Of course the impacts depend on how much soot, but a war between the US and Russia could produce a nuclear winter. For more information on our work and the consequences of nuclear war, please visit http://climate.envsci.rutgers.edu/nuclear/ Alan Robock Alan Robock, Distinguished Professor Department of Environmental Sciences Phone: +1-848-932-5751<tel:(848)%20932-5751> Rutgers University E-mail: rob...@envsci.rutgers.edu<mailto:rob...@envsci.rutgers.edu> 14 College Farm Road http://people.envsci.rutgers.edu/robock New Brunswick, NJ 08901-8551 ☮ https://twitter.com/AlanRobock On 7/26/2022 10:03 AM, Gideon Futerman wrote: As part of the RESILIENCER Project, we are looking at low probability high impact events and their relation to SRM. One important worry in this regards becomes termination shock, most importantly what Baum (2013) calls a "Double Catastrophe" where a global societal collapse caused by one catastrophe then causes termination shock, another catastrophe, which may convert the civilisational collapse into a risk of extinction. One such initial catastrophe may be nuclear war. Thus, the combination of SRM and nuclear war may be a significant worry. As such, I am posing the question to the google group: what would happen if SRM (either stratospheric or tropospheric- or space based if you want to go there) was terminated due to a nuclear war? What sort of effects would you expect to see? Would the combination worsen the effects of nuclear war or help ameliorate them? How would this differ between SRM types? -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to geoengineerin...@googlegroups.com<mailto:geoengineerin...@googlegroups.com>. 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