A Model Intercomparison of Stratospheric Solar Geoengineering by Accumulation-Mode Sulfate Aerosols

Weisenstein, Debra K.; Visioni, Daniele; Franke, Henning; Niemeier, Ulrike; Vattioni, Sandro; Chiodo, Gabriel; Peter, Thomas; Keith, David W.

doi:10.5194/acp-2021-569

Cited by 6 publications

(7 citation statements)

References 30 publications

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“…• Deployed material: (Lee et al 2021) assumes injections of SO 2 , which will oxidize into H 2 SO 4 (the sulfur species that is effective for radiative forcing) and coagulate into liquid super cooled aerosols after a month in the stratosphere. While recent studies have explored the direct injection of accumulation mode-H 2 SO 4 as an alternative to SO 2 (Vattioni et al 2019, Weisenstein et al 2021, neither the aeronautical tradeoffs associated with carrying this heavier substance nor the mechanics of venting it at the optimal particle size have been convincingly explored. Therefore, despite the prospective advantages of deploying other species of sulfur, we have retained the selection of SO 2 as made in (Lee et al 2021).…”

Section: Sai Subpolar Deployment Scenariomentioning

confidence: 99%

A subpolar-focused stratospheric aerosol injection deployment scenario

Smith

Bhattarai²,

MacMartin

et al. 2022

Environ. Res. Commun.

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Stratospheric aerosol injection (SAI) is a prospective climate intervention technology that would seek to abate climate change by deflecting back into space a small fraction of the incoming solar radiation. While most consideration given to SAI assumes a global intervention, this paper considers an alternative scenario whereby SAI might be deployed only in the subpolar regions. Subpolar deployment would quickly envelope the poles as well and could arrest or reverse ice and permafrost melt at high latitudes. This would yield global benefit by retarding sea level rise. Given that effective SAI deployment could be achieved at much lower altitudes in these regions than would be required in the tropics, it is commonly assumed that subpolar deployment would present fewer aeronautical challenges. An SAI deployment intended to reduce average surface temperatures in both the Arctic and Antarctic regions by 2 °C is deemed here to be feasible at relatively low cost with conventional technologies. However, we do not find that such a deployment could be undertaken with a small fleet of pre-existing aircraft, nor that relegating such a program to these sparsely populated regions would obviate the myriad governance challenges that would confront any such deployment. Nevertheless, given its feasibility and potential global benefit, the prospect of subpolar-focused SAI warrants greater attention.

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Section: Sai Subpolar Deployment Scenariomentioning

confidence: 99%

A subpolar-focused stratospheric aerosol injection deployment scenario

Smith

Bhattarai²,

MacMartin

et al. 2022

Environ. Res. Commun.

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“…Fixed SO2 and H2SO4 injections, 2040 conditions 3 Testbed Weisenstein et al (2021) for ODS and GHG, fixed SSTs at 1990 levels.…”

Section: H2so4mentioning

confidence: 99%

“…Pierce et al (2010) and following works (i.e., Benduhn et al (2016); Vattioni et al (2019)) have proposed direct injection of H 2 SO 4 particles into the accumulation mode, which would avoid H 2 SO 4 vapors formed from SO 2 oxidation from coagulating on pre-existing particles and having them grow too much. A testbed experiment was carried out Weisenstein et al (2021) comparing and contrasting the injection of SO 2 and H 2 SO 4 with the aim of observing the response of a subset of Ge-oMIP models with interactive aerosol microphysics. The injection of 5, 10 and 25 Tg of S in either form was simulated in two different injection strategies, one uniformly spreading the aerosols between 30 • N and 30 • S at all longitudes, and one injecting at 30 • N and 30 • S in only one gridbox.…”

Section: Past Progress In Official Geomip Experiments: Relevance In A...mentioning

confidence: 99%

Opinion: The Scientific and Community-Building Roles of the Geoengineering Model Intercomparison Project (GeoMIP) - Past, Present, and Future

Visioni

Kravitz²,

Robock³

et al. 2022

Preprint

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Abstract. The Geoengineering Model Intercomparison Project (GeoMIP) is a coordinating framework, started in 2010, that includes a series of standardized climate model experiments aimed at understanding the physical processes and projected impacts of solar geoengineering. Numerous experiments have been conducted, and numerous more have been proposed as "testbed'' experiments, spanning a variety of geoengineering techniques aimed at modifying the planetary radiation budget: stratospheric aerosol injection, marine cloud brightening, surface albedo modification, cirrus cloud thinning and sunshade mirrors. To date, more than one hundred studies have been published that used results from GeoMIP simulations. Here we provide a critical assessment of GeoMIP and its experiments. We discuss its successes and missed opportunities, for instance in terms of which experiments elicited more interest from the scientific community and which didn't, and the potential reasons why that happened. We also discuss the knowledge that GeoMIP has contributed to the field of geoengineering research and climate science as a whole: what have we learned in terms of inter-model differences, robustness of the projected outcomes for specific geoengineering methods and future areas of models' development that would be necessary in the future. We also offer multiple examples of cases where GeoMIP experiments were fundamental for international assessments of climate change. Finally, we provide a series of recommendations, regarding both future experiments and more general activities, with the goal of continuously deepening our understanding of the effects of potential geoengineering approaches, as well as reducing uncertainties in climate outcomes, important for assessing wider impacts on societies and ecosystems. In doing so, we refine the purpose of GeoMIP and outline a series of criteria whereby GeoMIP can best serve its participants, stakeholders, and the broader science community.

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“…Many chemical and aerosol processes (e.g., aerosol coagulation) are nonlinear processes that are highly dependent on concentration. Accurate estimation of nonlinear processes is essential in model simulations, which is especially true for the simulation of Accumulation‐Mode (AM) H 2 SO 4 injection for solar geoengineering (Weisenstein et al., 2022). Second‐order aerosol coagulation can greatly impact the particle size distribution of the injected AM H 2 SO 4 , which further influences the radiation transfer and climatic impacts of solar geoengineering in the simulation.…”

Section: Global Modelingmentioning

confidence: 99%

Developing a Plume‐in‐Grid Model for Plume Evolution in the Stratosphere

Hong-wei

Eastham

Keith

2022

J Adv Model Earth Syst

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Stratospheric emissions from aircraft or rockets are important sources of chemical perturbations. Small‐radius high‐aspect‐ratio plumes from stratospheric emissions are smaller than global Eulerian models' grid cells. To help global Eulerian models resolve subgrid plumes in the stratosphere, a Lagrangian plume model, comprising a Lagrangian trajectory model and an adaptive‐grid plume model with a sequence of plume cross‐section representations (from a highly resolved 2‐D grid to a simplified 1‐D grid based on a tradeoff between the accuracy and computational cost), is created and embedded into a global Eulerian (i.e., GEOS‐Chem) model to establish a multiscale Plume‐in‐Grid (PiG) model. We compare this PiG model to the GEOS‐Chem model based on a 1‐month simulation of continuous inert tracer emissions by aircraft in the stratosphere. In the PiG results, the final injected tracer is more concentrated and approximately 1/3 of the tracer is at concentrations 2–4 orders of magnitude larger compared to the GEOS‐Chem results. The entropy of injected tracer in the PiG results is 6% lower than the GEOS‐Chem results, indicating less tracer mixing. The total product mass from a hypothetical second‐order process (applied to the injected tracer) in the PiG results is 2 orders of magnitude larger than the GEOS‐Chem results. Increasing the GEOS‐Chem model's horizontal resolution 4‐fold is insufficient to resolve this product difference, while requiring over seven times the computational resources of the PiG model. This paper describes the PiG model framework and parameterization of plume physical processes. Chemical and aerosol processes will be introduced in the future.

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A Model Intercomparison of Stratospheric Solar Geoengineering by Accumulation-Mode Sulfate Aerosols

Cited by 6 publications

References 30 publications

A subpolar-focused stratospheric aerosol injection deployment scenario

A subpolar-focused stratospheric aerosol injection deployment scenario

Opinion: The Scientific and Community-Building Roles of the Geoengineering Model Intercomparison Project (GeoMIP) - Past, Present, and Future

Developing a Plume‐in‐Grid Model for Plume Evolution in the Stratosphere

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