We do have a study case in the paper where we inject in the upper troposphere rather than at the surface, for which the load necessary is much lower and the surface concentrations of COS result to be lower. As Alan said, this still needs a lot of research in various fields (ecology especially), but it might have some potential overall if higher altitudes result to be unreachable.
> On 26 Jun 2022, at 02:17, Michael MacCracken <[email protected]> wrote: > > > But it also does not have to be released at surface to be effective--release > it from remote mountain tops or otherwise at elevated levels. Also, the study > here was for a rather high loading--if the world would get busy on emissions > reductions and the desired effect were to shave off peak warming, the > concentrations would be lower. There is no perfect situation and the question > is the relative tradeoffs for realistic applications. And if one could > combine it with something less toxic that would only dissociate with high UV, > the COS would end up primarily in the stratosphere. So, chemists need to keep > searching. > > Mike > >> On 6/25/22 9:56 PM, Ron Baiman wrote: >> Thanks Alan. Yes, more investigation on this is needed, as noted in my >> blurb as well. I'm adding the lead author to this discussion in the event >> that she might be interested in participating in this discussion and is not >> in any of the lists. >> >> Below is a snippet from the paper (p. 57580 that I think is relevant to your >> point. >> >> Ron >> >> >> "In quiescent volcanic conditions, COS is the main contributor >> of sulfate aerosols in the Junge layer (Brühl et al., 2012), >> where, after photodissociation by ultraviolet light and oxidation >> processes, it is turned into SO2 and subsequently oxidized >> into sulfuric acid, forming sulfate aerosols (Crutzen, >> 1976). It is naturally produced by various biological processes >> and environments, such as saline ecosystems, rainwater >> (Mu et al., 2004), and biomass burning. Furthermore, it is >> also produced in various industrial processes (Lee and Brimblecombe, >> 2016) after CS2 is oxidized. Its chemical life is >> very long (35 years; Brühl et al., 2012), and thus, its main >> sink is the uptake from oxic soils (Kuhn and Kesselmeier, >> 2000; Steinbacher et al., 2004) and vegetation (Sandoval- >> Soto et al., 2005). In the concentrations found in the atmosphere, >> it is not a toxic gas for humans; negative effects >> have not been found even at around 50 ppm (parts per >> million), which is 100 000 times more than the background >> mixing ratio, and for long exposure times in mice and rabbits >> (Svoronos and Bruno, 2002). Higher concentrations than >> that can, however, be harmful (Bartholomaeus and Haritos, >> 2006). Not much is known, however, about the response of >> ecosystems in the presence of high concentrations of COS. >> Stimler et al. (2010) showed that high levels of COS enhance >> the stomatal conductance of some plants, which might >> in turn have other unforeseen effects; furthermore, Conrad >> and Meuser (2000) proposed that high COS concentrations >> may interact with soils and possibly change soil pH. For the >> reasons listed above, Crutzen (2006) discarded the idea of >> using surface emissions of COS to increase the stratospheric >> aerosol burden. >> In this work, we use the University of L’Aquila Climate >> Chemistry Model (ULAQ-CCM) to perform simulations to >> verify if the increase in surface emissions of COS would be a >> viable form of sulfate geoengineering, by obtaining a stratospheric >> aerosol optical depth (AOD) similar to that obtained >> with the injection of 8 TgSO2 in the stratosphere. We also >> perform simulations where the release of COS is localized >> in the tropical upper troposphere. This allows us to investigate >> whether the increase in surface concentrations of COS >> can be avoided, while, at the same time, circumventing the >> need to reach altitudes that are currently unattainable with >> modern aircraft (Smith et al., 2020). Together with assessing >> the resulting aerosol cloud, we also explore the eventual side >> effects on key chemical components in the atmosphere in order >> to determine how the side effects from COS-induced sulfate geoengineering >> compare with those from SO2-induced sulfate geoengineering." >> >> On Sat, Jun 25, 2022 at 2:22 PM Alan Robock ☮ <[email protected]> >> wrote: >>> But it's nasty stuff. Please keep in mind the last sentence of the >>> abstract, "However, our assumption that the rate of COS uptake by soils and >>> plants does not vary with increasing COS concentrations will need to be >>> investigated in future work, and more studies are needed on the prolonged >>> exposure effects to higher COS values in humans and ecosystems." >>> >>> From the National Library of Medicine, >>> https://pubchem.ncbi.nlm.nih.gov/compound/Carbonyl-sulfide : >>> >>> "Carbonyl sulfide is a colorless, poisonous, flammable gas with a distinct >>> sulfide odor. The gas is toxic and narcotic in low concentrations and >>> presents a moderate fire hazard." >>> >>> Alan >>> >>> Alan Robock, Distinguished Professor >>> Department of Environmental Sciences Phone: +1-848-932-5751 >>> 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 >>>> On 6/25/22 2:25 PM, Ron Baiman wrote: >>>> Dear Colleagues, >>>> >>>> FYI, if you haven't heard or seen this. >>>> >>>> Carbonyl Sulfide (COS) aerosols released from the earth's surface and in >>>> models appear to have a cooling impact similar to SO2 released in the >>>> stratosphere. More research on the potential impacts of increased COS >>>> released from the surface into the troposphere, that (as I recall from the >>>> podcast) rises and stays in the stratosphere for an extended period of >>>> time, for example on soil and plant uptake is needed, but as Andrew >>>> opines, this method may be an "Sulfate Geoengineering COS Surface >>>> Radiative Forcing" (SG-COS-SRF) surface aerosol release breakthrough as >>>> it requires no aviation (conventional or other) or advanced injection >>>> technology. >>>> >>>> Listen here: >>>> https://podcasts.apple.com/us/podcast/using-tropospheric-cos-emissions-for-srm-quaglia/id1529459393?i=1000565776236 >>>> >>>> Paper Abstract: >>>> An approach to sulfate geoengineering with >>>> surface emissions of carbonyl sulfide >>>> Ilaria Quaglia1, Daniele Visioni2, Giovanni Pitari1, and Ben Kravitz3,4 >>>> 1Department of Physical and Chemical Sciences, Università dell’Aquila, >>>> 67100 L’Aquila, Italy >>>> 2Sibley School for Mechanical and Aerospace Engineering, Cornell >>>> University, Ithaca, NY 14853, USA >>>> 3Department of Earth and Atmospheric Science, Indiana University, >>>> Bloomington, IN, USA >>>> 4Atmospheric Sciences and Global Change Division, Pacific Northwest >>>> National Laboratory, >>>> Richland, WA, USA >>>> Correspondence: Ilaria Quaglia ([email protected]) >>>> Received: 29 September 2021 – Discussion started: 11 October 2021 >>>> Revised: 16 March 2022 – Accepted: 28 March 2022 – Published: 3 May 2022 >>>> Abstract. Sulfate geoengineering (SG) methods based on lower stratospheric >>>> tropical injection of sulfur dioxide >>>> (SO2) have been widely discussed in recent years, focusing on the direct >>>> and indirect effects they would have on >>>> the climate system. Here a potential alternative method is discussed, >>>> where sulfur emissions are located at the >>>> surface or in the troposphere in the form of carbonyl sulfide (COS) gas. >>>> There are two time-dependent chemistry– >>>> climate model experiments designed from the years 2021 to 2055, assuming a >>>> 40 Tg−S yr−1 artificial global flux >>>> of COS, which is geographically distributed following the present-day >>>> anthropogenic COS surface emissions >>>> (SG-COS-SRF) or a 6 Tg − S yr−1 injection of COS in the tropical upper >>>> troposphere (SG-COS-TTL). The >>>> budget of COS and sulfur species is discussed, as are the effects of both >>>> SG-COS strategies on the stratospheric >>>> sulfate aerosol optical depth (∼ 1τ = 0.080 in the years 2046–2055), >>>> aerosol effective radius (0.46 μm), surface >>>> SOx deposition (+8.9 % for SG-COS-SRF; +3.3 % for SG-COS-TTL), and >>>> tropopause radiative forcing (RF; >>>> ∼ −1.5 W m−2 in all-sky conditions in both SG-COS experiments). Indirect >>>> effects on ozone, methane and >>>> stratospheric water vapour are also considered, along with the COS direct >>>> contribution. According to our model >>>> results, the resulting net RF is −1.3 W m−2, for SG-COS-SRF, and −1.5 W >>>> m−2, for SG-COS-TTL, and it is >>>> comparable to the corresponding RF of −1.7 W m−2 obtained with a sustained >>>> injection of 4 Tg − S yr−1 in the >>>> tropical lower stratosphere in the form of SO2 (SG-SO2, which is able to >>>> produce a comparable increase of the >>>> sulfate aerosol optical depth). Significant changes in the stratospheric >>>> ozone response are found in both SG-COS >>>> experiments with respect to SG-SO2 (∼ 5 DU versus +1.4 DU globally). >>>> According to the model results, the >>>> resulting ultraviolet B (UVB) perturbation at the surface accounts for >>>> −4.3 % as a global and annual average >>>> (versus −2.4 % in the SG-SO2 case), with a springtime Antarctic decrease >>>> of −2.7 % (versus a +5.8 % increase >>>> in the SG-SO2 experiment). Overall, we find that an increase in COS >>>> emissions may be feasible and produce a >>>> more latitudinally uniform forcing without the need for the deployment of >>>> stratospheric aircraft. However, our >>>> assumption that the rate of COS uptake by soils and plants does not vary >>>> with increasing COS concentrations >>>> will need to be investigated in future work, and more studies are needed >>>> on the prolonged exposure effects to >>>> higher COS values in humans and ecosystems. >>>> >>>> Full paper: >>>> https://acp.copernicus.org/articles/22/5757/2022/ >>>> >>>> Best, >>>> Ron >>>> -- >>>> 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/CAPhUB9DjU62gj9J5-wJZ4%3D%3Drku-8-_%2BQWPG%3D6NT5L3fDKB%2B%3Dow%40mail.gmail.com. >> -- >> You received this message because you are subscribed to the Google Groups >> "Healthy Planet Action Coalition" 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/healthy-planet-action-coalition/CAPhUB9Acn4TkjQ%3DeHT38k5MkDE%2Bz9cvMcXh5j5snBqaaahNboQ%40mail.gmail.com. >> For more options, visit https://groups.google.com/d/optout. > -- > 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/976f3f23-21fc-980e-b242-eb6b22b4a22d%40comcast.net. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. 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