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 Roadhttp://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−1artificial 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−1injection 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
SOxdeposition (+8.9 % for SG-COS-SRF;+3.3 % for SG-COS-TTL), and
tropopause radiative forcing (RF;
∼ −1.5 W m−2in 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−2obtained with a
sustained injection of 4 Tg−S yr−1in 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
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