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 <[email protected]> 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, <[email protected]> > 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 <[email protected]> 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 >> 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 >>> <(848)%20932-5751> >>> Rutgers University E-mail: >>> [email protected] >>> 14 College Farm Road http://people.envsci.rutgers.edu/robock >>> New Brunswick, NJ 08901-8551 ☮ https://twitter.com/AlanRobock >>> >>> [image: Signature] >>> >>> >>> 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 >>>> <(848)%20932-5751> >>>> Rutgers University E-mail: >>>> [email protected] >>>> 14 College Farm Road http://people.envsci.rutgers.edu/robock >>>> New Brunswick, NJ 08901-8551 ☮ https://twitter.com/AlanRobock >>>> >>>> [image: Signature] >>>> >>>> >>>> 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 [email protected]. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/geoengineering/8d0d8c0a-0f0d-440c-9bb5-f8641560e4a0n%40googlegroups.com >>>> <https://groups.google.com/d/msgid/geoengineering/8d0d8c0a-0f0d-440c-9bb5-f8641560e4a0n%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>>> >>>> -- >>> 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 [email protected]. >>> >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/geoengineering/b541017e-b87b-4492-b840-91e39d0b0601n%40googlegroups.com >>> <https://groups.google.com/d/msgid/geoengineering/b541017e-b87b-4492-b840-91e39d0b0601n%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >>> >>> -- >> 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 [email protected]. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/geoengineering/419bee77-0d9a-416a-9b38-5fc6f584ba3cn%40googlegroups.com >> <https://groups.google.com/d/msgid/geoengineering/419bee77-0d9a-416a-9b38-5fc6f584ba3cn%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> >> -- > 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 [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/geoengineering/CAK73TM%2BA0dvOcYEOQd1_CKFE6YM1KZjTSQUo2HvZqhvRY4HMUw%40mail.gmail.com > <https://groups.google.com/d/msgid/geoengineering/CAK73TM%2BA0dvOcYEOQd1_CKFE6YM1KZjTSQUo2HvZqhvRY4HMUw%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- 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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/geoengineering/CAGQ2tEqL6%2BWSDBBQZnGjVwgPLz81mW7-hMjuRih_e6u9naRGcw%40mail.gmail.com.
