It would be good to know if something about my calculations here are fundamentally wrong. I am no aerosol expert by any margins, and as seen, my model is pretty much the most simple possible thing that I could make on this, but it does seem to give an indication against the "double catastrophe" thesis. Please let me know if I am wrong on this
On Monday, 15 August 2022 at 16:15:09 UTC+1 Gideon Futerman wrote: > I've just tried running some really simple equations to look at forcing, > so I thought I would share my back of the envelope calculations and see > what you all think. > So I tried to calculate what would happen to forcing in a 5Tg of soot > released (likely due to a regional nuclear war) combined with a termination > shock, possibly due to cascading impacts of the nuclear war on the global > economy, for example. I used a value of -15Wm^-2 for the maximum forcing > from the soot, and a e-folding time of 4.6 years [Robock et al 2007]. I > then used a solar geoengineering forcing of -4Wm^-2 (the maximum forcing > from Pinatubo) and an e-folding time of 1 year. > I treated the forcing relative to the nongeoengineered world prior to the > nuclear winter, so treated that as 0Wm^-2 and the forcing of the > geoengineered world before the nuclear winter at 4Wm^-2. The soot was > injected at the end of year 1. Immediately after soot injection at the end > of year 1, the forcing(geo) is -19Wm^-2 and the forcing(nongeo) is > -15Wm^-2. At the end of year 2, so 1 year after the soot injection, the > forcing (geo) is 14Wm^-2 and the forcing(nongeo) is 12Wm^-2, so the delta > for the forcing(geo) relative to their initial values is 16.7% less than > the delta forcing (nongeo). > The two equations I used for year 1 were as follows: > y=0 (nongeo) > y=-4 (geo) > The two equations I used for the end of year 1 onwards were > y=-15e ^(-1/4.6 * (t-1)) [nongeo] > y=-15e^(-1/4.6 * (t-1)) -3e^(-(t-1)) [geo] > > The graph I got is here (https://www.desmos.com/calculator/duz3tlpkky) > It seems to me for a relatively small scale nuclear winter and a > moderately large SRM forcing that the forcing impacts of termination shock > are not negligable. This obviously doesn't necessarily translate to climate > respone > > I did a few others for other SRM and nuclear war scenarios, which I can > send through if people were interested. > Obviously these calculations are massively simplified, back of the > envelope calculations, but I would nonetheless be interested in peoples > thoughts on it. Apologies if I have messed up somewhere > Kind Regards > Gideon > > On Sunday, 7 August 2022 at 01:36:17 UTC+1 Russell Seitz wrote: > >> I'm surprised Alan should neglect to cite studies other than his own, as >> climate responses to carbon aerosols in the atmosphere vary greatly. The >> recent literature is illustrative- a growing concern is the impact of >> black carbon from satellite and spacecraft launches, which may warm the >> upper atmosphere rather than cool it: >> >> Journal of Geophysical Research: Atmospheres >> <https://agupubs.onlinelibrary.wiley.com/journal/21698996> 1June2022 >> >> The Climate and Ozone Impacts of Black Carbon Emissions From Global >> Rocket Launches >> Christopher M Maloney >> <https://agupubs.onlinelibrary.wiley.com/action/doSearch?ContribAuthorRaw=Maloney%2C+Christopher+M> >> , Robert W Portmann >> <https://agupubs.onlinelibrary.wiley.com/action/doSearch?ContribAuthorRaw=Portmann%2C+Robert+W> >> , Martin N Ross >> <https://agupubs.onlinelibrary.wiley.com/action/doSearch?ContribAuthorRaw=Ross%2C+Martin+N> >> , Karen H Rosenlof >> <https://agupubs.onlinelibrary.wiley.com/action/doSearch?ContribAuthorRaw=Rosenlof%2C+Karen+H> >> >> https://doi.org/10.1029/2021JD036373 >> >> Aerosol emissions from spaceflight activities play a small but increasing >> role in the background stratospheric aerosol population. Rockets used by >> the global launch industry emit black carbon (BC) particles directly into >> the stratosphere where they accumulate, absorb solar radiation, and warm >> the surrounding air. We model the chemical and dynamical response of the >> atmosphere to northern mid-latitude rocket BC emissions. We initially >> examine emissions at a rate of 10 Gg per year, which is an order of >> magnitude larger than current emissions, but consistent with extrapolations >> of space traffic growth several decades into the future. We also perform >> runs at 30 and 100 Gg per year in order to better delineate the >> atmosphere's response to rocket BC emissions. We show that a 10 Gg/yr >> rocket BC emission increases stratospheric temperatures by as much as 1.5 K >> in the stratosphere. Changes in global circulation also occur. For example, >> the annual subtropical jet wind speeds slow down by as much as 5 m/s, while >> a 10%–20% weakening of the overturning circulation occurs in the northern >> hemisphere during multiple seasons. Warming temperatures lead to a ozone >> reduction in the northern hemisphere by as much as 16 DU in some months. >> The climate response increases in a near linear fashion when looking at >> larger 30 and 100 Gg emission scenarios. Comparing the amplitude of the >> atmospheric response using different emission rates provides insight into >> stratospheric adjustment and feedback mechanisms. Our results show that the >> stratosphere is sensitive to relatively modest BC injections. >> >> On Tuesday, July 26, 2022 at 10:20:44 AM UTC-4 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: >>> rob...@envsci.rutgers.edu >>> 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 geoengineerin...@googlegroups.com. >>> 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 geoengineering+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/geoengineering/a44c6f86-8364-4d1b-9721-3d346af5a3d8n%40googlegroups.com.
