*WEEKLY SUMMARY (11 SEPTEMBER - 17 SEPTEMBER 2023)* ------------------------------ RESEARCH PAPERSImportance of microphysical settings for climate forcing by stratospheric SO2 injections as modelled by SOCOL-AERv2 <https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1726/>
Vattioni, S., Stenke, A., Luo, B., Chiodo, G., Sukhodolov, T., Wunderlin, E., & Peter, T. (2023). Importance of microphysical settings for climate forcing by stratospheric SO 2 injections as modelled by SOCOL-AERv2. *EGUsphere*, *2023*, 1-25. *Abstract:* Solar radiation management as a sustained deliberate source of SO2 into the stratosphere (strat-SRM) has been proposed as an option for climate intervention. Global interactive aerosol-chemistry-climate models are often used to investigate the potential cooling efficiencies and side effects of hypothesised strat-SRM scenarios. A recent strat-SRM model intercomparison study for composition-climate models with interactive stratospheric aerosol suggests that the modelled climate response to a particular assumed injection strategy, depends on the type of aerosol microphysical scheme used (e.g., modal or sectional representation), alongside also host model resolution and transport. Compared to short-duration volcanic SO2 emission, the continuous SO2 injections in strat-SRM scenarios may pose a greater challenge to the numerical implementation of of microphysical processes such as nucleation, condensation, and coagulation. This study explores how changing the timesteps and sequencing of microphysical processes in the sectional aerosol-chemistry-climate model SOCOL-AERv2 (40 size bins) affect model predicted climate and ozone layer impacts considering strat-SRM SO2 injections of of 5 and 25 Tg(S) yr-1 at 20 km altitude between 30° S and 30° N. The model experiments consider year 2040 boundary conditions for ozone depleting substances and green house gases. We focus on the length of the microphysical timestep and the call sequence of nucleation and condensation, the two competing sink processes for gaseous H2SO4. Under stratospheric background conditions, we find no effect of the microphysical setup on the simulated aerosol properties. However, at the high sulfur loadings reached in the scenarios injecting 25 Mt/yr of sulfur with a default microphysical timesetp of 6 min, changing the call sequence from the default "condensation first" to "nucleation first" leads to a massive increase in the number densities of particles in the nucleation mode (*R* < 0.01 μm) and a small decrease in coarse mode particles (*R* > 1 μm). As expected, the influence of the call sequence becomes negligible when the microphysical timestep is reduced to a few seconds, with the model solutions converging to a size distribution with a pronounced nucleation mode. While the main features and spatial patterns of climate forcing by SO2 injections are not strongly affected by the microphysical configuration, the absolute numbers vary considerably. For the extreme injection with 25 Tg(S) yr-1, the simulated net global radiative forcing ranges from -2.3 W m-2 to -5.3 W m-2, depending on the microphysical configuration. “Nucleation first” shifts the size distribution towards radii better suited for solar scattering (0.3 μm < *R* < 0.4 μm), enhancing the intervention efficiency. The size-distribution shift however generates more ultra-fine aerosol particles, increasing the surface area density, resulting in 10 DU less ozone (about 3 % of total column) in the northern midlatitudes and 20 DU less ozone (6 %) over the polar caps, compared to the "condensation first" approach. Our results suggest that a reasonably short microphysical time step of 2 minutes or less must be applied to accurately capture the magnitude of the H2SO2 supersaturation resulting from SO2 injection scenarios or volcanic eruptions. Taken together these results underscore how structural aspects of model representation of aerosol microphysical processes become important under conditions of elevated stratospheric sulfur in determining atmospheric chemistry and climate impacts. No Emergency Brake: Slow Ocean Response to Abrupt Stratospheric Aerosol Injection <https://essopenarchive.org/doi/full/10.22541/essoar.169447423.32818318/v1> Pflüger, D., Wieners, C. E., van Kampenhout, L., Wijngaard, R., & Dijkstra, H. A. (2023). No Emergency Brake: Slow Ocean Response to Abrupt Stratospheric Aerosol Injection. *Authorea Preprints*. *Abstract*: Given the possibility of irreversible changes to the Earth system, technological interventions such as solar radiation management (SRM) are sometimes framed as possible climate emergency brakes. However, little knowledge exists on the efficacy of such disruptive interventions. To fill in this gap, we perform Community Earth System Model 2 (CESM 2) simulations of a SSP5-8.5 scenario on which we impose either gradual early-century SRM to stabilise surface temperatures or a rapid late-century cooling, both realised via stratospheric aerosol injection (SAI). While both scenarios cool Earth’s surface, we find that ocean conditions differ drastically. The rapid-cooling scenario fails to dissipate sub-surface ocean heat content (OHC), ends up in a weaker AMOC state and does not restore an ailing North Atlantic deep convection. Furthermore, the weakened AMOC state mediates the climate response to rapid SAI, thus inducing an interhemispheric temperature asymmetry. Our results advise caution when considering SAI as an emergency intervention. ------------------------------ THESISA Discourse Analysis of the Debate on Geoengineering in Japan <https://studenttheses.uu.nl/handle/20.500.12932/44895> ------------------------------ REPORTSReducing the Risks of Climate Overshoot <https://www.overshootcommission.org/_files/ugd/0c3b70_bab3b3c1cd394745b387a594c9a68e2b.pdf> <https://www.overshootcommission.org/_files/ugd/0c3b70_bab3b3c1cd394745b387a594c9a68e2b.pdf> ------------------------------ WEB POSTSDesperate Measures: Geoengineering as Humankind's Last Climate Gamble <https://thesunflowerparadigm.blogspot.com/2023/08/desperate-measures-geoengineering-as.html> (The Sunflower Paradigm)Empowering Youth for Climate Intervention: Insights from the 2023 Global Youth Summit on Near-term Climate Risks and Interventions <https://www.silverlining.ngo/insights/empowering-youth-for-climate-intervention-global-youth-summit-2023> (SilverLining)Dear Colleague Letter: CO2 Removal and Solar Radiation Modification Strategies: Science, Governance and Consequences <https://www.nsf.gov/pubs/2023/nsf23151/nsf23151.jsp?org=NSF> (NSF)Experts call for a global moratorium on efforts to geoengineer climate <https://www.theguardian.com/environment/2023/sep/14/experts-call-for-global-moratorium-on-efforts-to-geoengineer-climate?CMP=Share_iOSApp_Other> (The Guardian)EarthShine Geoengineering Inc. Awarded Patent for Groundbreaking Climate Crisis Solution <https://www.einnews.com/pr_news/655691573/earthshine-geoengineering-inc-awarded-patent-for-groundbreaking-climate-crisis-solution> (Newswires)Global SRM Technologies - A Tier List (Plan A+) Plan A+ Global SRM Technologies - A Tier List <https://peteirvine.substack.com/p/global-srm-technologies-a-tier-list?utm_source=substack&utm_campaign=post_embed&utm_medium=email> Stratospheric Aerosol Injection (SAI) geoengineering is my main research focus and the focus of this substack, but why? There are several other SRM technologies, what makes SAI special? In this post I’m going to populate a “Tier List” of global SRM technologies (Figure 1), i.e., I’m going to rank them as means of counteracting global climate change. Let… Read more <https://peteirvine.substack.com/p/global-srm-technologies-a-tier-list?utm_source=substack&utm_campaign=post_embed&utm_medium=email> 5 days ago · 1 comment · Pete Irvine ------------------------------ *UPCOMING EVENTS*(NEW) Professor Chris Field in conversation on the Climate Overshoot Commission at the Healthy Planet Action Coalition <https://groups.google.com/g/geoengineering/c/ML8O-ULnDp0> | 21 September 2023*Solar Climate Intervention Virtual Symposia <https://sites.google.com/view/solargeo-symposium/home> | 22 September 2023* (NEW) Making well-informed decisions about solar radiation modification by Carnegie Climate Governance Initiative (C2G), UNESCO, The Energy and Resources Institute (TERI), The Degrees Initiative <https://sciencesummitunga78.sched.com/event/1O4is> | 26 September 2023*Solar Geoengineering Futures: Interdisciplinary Research to Inform Decisionmaking by Resources for Future <https://www.rff.org/events/conferences/solar-geoengineering-futures-current-research-and-uncertainties/> | 28-29 September 2023**Conference—Solar Geoengineering Futures: Current Research and Uncertainties by Resources for the Future (RFF) <https://www.rff.org/events/conferences/solar-geoengineering-futures-current-research-and-uncertainties/>| 28-29 September 2023*(NEW) Perspectives on Solar Radiation Management Governance by Geneva Environment Network <https://www.genevaenvironmentnetwork.org/events/perspectives-on-solar-radiation-management-governance/> | 12 October 2023*Climate Engineering (GRS) <https://www.grc.org/climate-engineering-grs-conference/2024/>| 17-18 February 2024**GRC Climate Engineering 2024 <https://www.grc.org/climate-engineering-conference/2024/>| 18-23 February 2024* ------------------------------ PODCASTSPutting a halt to geoengineering — by accident | Catalyst with Shayle Kann <https://www.canarymedia.com/podcasts/catalyst-with-shayle-kann/putting-a-halt-to-geoengineering-by-accident> *“In this episode, Shayle talks to Dan Visioni <https://dan-visioni.github.io/>, a climate scientist and assistant professor at Cornell University’s Department of Earth and Atmospheric Sciences. They cover topics including**-The mechanism behind marine cloud brightening and how it differs from stratospheric sulfate injection.**-Why the warming effect was so strong in the North Atlantic in particular.**-What we still don’t understand about the impact on global mean temperatures and regional weather, such as heat waves and hurricanes.**-What this accidental experiment teaches us about how to conduct a deliberate geoengineering experiment.”* ------------------------------ YOUTUBE VIDEOSOvershooting 1.5°C: the latest science on the risks and action needed | Climate Analytics <https://www.youtube.com/watch?v=z1NqMDRD0XU> *“This webinar, hosted by the Horizon Europe project looking at climate overshoot (PROVIDE), features presentations and expert discussion on what the latest science suggests overshoot of 1.5°C could look like, what the implications are for our planet and societies, and how this should inform climate action today.**Implications for the speed of emissions reductions, impacts and adaptation efforts, loss and damage are touched on, as well as expert views on untested technologies such as solar geoengineering.”* 2023 UN 8th STI Forum - Solar Radiation Modification and youth perspectives on its governance | Clara Botto <https://www.youtube.com/watch?v=mskvJM6E6Rg> *“Brief presentation of our science-policy brief published at the 8th STI Forum.”* Youth Summit 2023: Youth in Pakistan Call for Increased Research into Climate Interventions | SilverLining <https://www.youtube.com/watch?v=esDHWoKZ3Io> *“SilverLining’s Global Young Leaders Initiative (GYLI) hosted its annual youth summit - “Can We Keep 1.5°C Alive?” - on May 4, 2023. The event brought together young leaders, advocates, policymakers, and climate scientists, as well as global experts on climate intervention research and international governance, in order to facilitate an open and interactive dialogue in which young people’s voices are central.”* Youth Summit 2023: Climate Intervention Research A Necessity for Science-based Decision-making | SilverLining <https://www.youtube.com/watch?v=Az-FuGlH1_Q>Solar Radiation Modification: How do we plan to govern discussions? | SRM Youth Watch <https://www.youtube.com/watch?v=NiJQOiCHhDk> *“This animation is brought to you by Solar Radiation Modification Youth Watch (SRM Youth Watch), as an artistic contribution regarding the necessity to enhance inclusive, transparent and accountable global governance frameworks around Solar Radiation Modification (SRM). **At SRM Youth Watch, we are all about youth engagement! We provide accessible learning resources and share captivating creative content, inviting young minds to immerse themselves in the science, governance, and diverse stakeholder viewpoints surrounding SRM. Our platform is a dynamic space where the younger generation collaborates and contributes their insights to the discourse on Solar Radiation Modification. We're here to raise awareness, foster collaboration, and amplify youth voices in the governance of emerging technologies that has the potential to alter our Earth’s temperature.”* ------------------------------ *DEADLINES**PhD opportunity at University of Tasmania | Research Title: Solar Radiation Management in Antarctica: International Law and Policy Implications <https://www.utas.edu.au/research/degrees/available-projects/projects/law/antarctic-solar-radiation-management> | Deadline: 25 September 2023**(NEW) The Climate Intervention Environmental Impact Fund <https://cieif.org/> | Application Deadline: 01 November 2023* -- 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/CAHJsh9_2SXcRrog5shzaO%3DeeMke_0oHuQr%3DD7ORkdJi0k74QNw%40mail.gmail.com.
