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WEEKLY SUMMARY (15 JANUARY - 21 JANUARY 2024) <https://substack.com/app-link/publications/1346479/drafts/cb9b3cfc-a516-4367-b3ab-f864ca032617?publication_id=1346479&post_id=140935232&utm_source=post-email-title&utm_campaign=email-post-title&isFreemail=false>Links to recent scientific papers, web posts, upcoming events, job opportunities, podcasts, and event recordings, etc. on Solar Radiation Management Technology. RESEARCH PAPERSSensitivities of Large Eddy Simulations of Aerosol Plume Transport and Cloud Response <https://essopenarchive.org/doi/full/10.22541/essoar.170365352.28240067/v1> Dhandapani, C., Kaul, C. M., Pressel, K. G., Wood, R., & Kulkarni, G. (2023). Sensitivities of Large Eddy Simulations of Aerosol Plume Transport and Cloud Response. *Authorea Preprints*.*Abstract*Cloud responses to surface-based sources of aerosol perturbation depend in part on the characteristics of the aerosol transport to cloud base and the resulting spatial and temporal distribution of aerosol. However, interactions among aerosol, cloud, and turbulence processes complicate the prediction of this aerosol transport and can obscure diagnosis of the aerosols' effects on cloud and turbulence properties. Here, scenarios of plume injection below a marine stratocumulus cloud are modeled using large eddy simulations coupled to a prognostic bulk aerosol and cloud microphysics scheme. Both passive plumes, consisting of an inert tracer, and active plumes are investigated, where the latter are representative of saltwater droplet plumes such as have been proposed for marine cloud brightening. Passive plume scenarios show a spurious in-plume cloud brightening due solely to the connections between updrafts, cloud condensation, and scalar transport. Numerical sensitivities are first assessed to establish a suitable model configuration. Then sensitivity to particle injection rate is investigated. Trade-offs are identified between the number of injected particles and the suppressive effect of droplet evaporation on plume loft and spread. Furthermore, as the in-plume brightening effect does not depend significantly on injection rate given a suitable definition of perturbed versus unperturbed regions of the flow, plume area is a key controlling factor on the overall cloud brightening effect of an aerosol perturbation. Validating a microphysical prognostic stratospheric aerosol implementation in E3SMv2 using the Mount Pinatubo eruption <https://egusphere.copernicus.org/preprints/2024/egusphere-2023-3041/> Brown, H. Y., Wagman, B., Bull, D., Peterson, K., Hillman, B., Liu, X., ... & Lin, L. (2024). Validating a microphysical prognostic stratospheric aerosol implementation in E3SMv2 using the Mount Pinatubo eruption. *EGUsphere*, *2024*, 1-46.*Abstract*This paper describes the addition of a stratospheric prognostic aerosol (SPA) capability – developed with the goal of accurately simulating aerosol formation following explosive volcanic eruptions – in the Department of Energy (DOE) Earth Energy Exascale Model, version 2 (E3SMv2). The implementation includes changes to the 4-mode Modal Aerosol Module microphysics in the stratosphere to allow for larger particle growth and more accurate stratospheric aerosol lifetime following the Mt. Pinatubo eruption. E3SMv2-SPA reasonably reproduces stratospheric aerosol lifetime, burden, and aerosol optical depth when compared to remote sensing observations and the interactive chemistry-climate model, CESM2-WACCM. *Global stratospheric aerosol size distributions identify the nucleation and growth of sulfate aerosol from volcanically injected SO2 from both major and minor volcanic eruptions from 1991 to 1993. *Modeled aerosol effective radius is consistently lower than satellite and in-situ measurements (max differences of ~30 %). Comparisons with in-situ size distribution samples indicate that this underestimation is due to both E3SMv2-SPA and CESM2-WACCM simulating too small of accumulation and coarse mode aerosol 6–18 months post-eruption, with E3SMv2-SPA simulating ~50 % the coarse mode geometric mean diameters of observations 11 months post-eruption. Effective radii from the models and observations are used to calculate offline scattering and absorption efficiencies to explore the implications of smaller simulated aerosol size on the Mt. Pinatubo climate impacts. Scattering efficiencies at wavelengths of peak solar irradiance (~0.5 µm) are 10–80 % higher for daily samples in models relative to observations through 1993, suggesting higher diffuse radiation at the surface and a larger cooling effect in the models. Absorption efficiencies at the peak wavelengths of outgoing terrestrial radiation (~10 µm) are 15–40 % lower for daily samples in models relative to observations suggesting an underestimation in stratospheric heating in the models. The similar performance of CESM2-WACCM and E3SMv2-SPA makes E3SMv2-SPA a viable alternative to simulating climate impacts from stratospheric sulfate aerosols. Volcanic forcing of high-latitude Northern Hemisphere eruptions <https://www.nature.com/articles/s41612-023-00539-4> Fuglestvedt, H. F., Zhuo, Z., Toohey, M., & Krüger, K. (2024). Volcanic forcing of high-latitude Northern Hemisphere eruptions. *npj Climate and Atmospheric Science*, *7*(1), 10.*Abstract*High-latitude explosive volcanic eruptions can cause substantial hemispheric cooling. Here, we use a whole-atmosphere chemistry-climate model to simulate Northern Hemisphere (NH) high-latitude volcanic eruptions of magnitude similar to the 1991 Mt. Pinatubo eruption. Our simulations reveal that the initial stability of the polar vortex strongly influences sulphur dioxide lifetime and aerosol growth by controlling the dispersion of injected gases after such eruptions in winter. Consequently, atmospheric variability introduces a spread in the cumulative aerosol radiative forcing of more than 20%. We test the aerosol evolution’s sensitivity to co-injection of sulphur and halogens, injection season, and altitude, and show how aerosol processes impact radiative forcing. Several of these sensitivities are of similar magnitude to the variability stemming from initial conditions, highlighting the significant influence of atmospheric variability. We compare the modelled volcanic sulphate deposition over the Greenland ice sheet with the relationship assumed in reconstructions of past NH eruptions. Our analysis yields an estimate of the Greenland transfer function for NH extratropical eruptions that, when applied to ice core data, produces volcanic stratospheric sulphur injections from NH extratropical eruptions 23% smaller than in currently used volcanic forcing reconstructions. Furthermore, the transfer function’s uncertainty, which propagates into the estimate of sulphur release, needs to be at least doubled to account for atmospheric variability and unknown eruption parameters. Our results offer insights into the processes shaping the climatic impacts of NH high-latitude eruptions and highlight the need for more accurate representation of these events in volcanic forcing reconstructions. [image: figure 1] <https://www.nature.com/articles/s41612-023-00539-4> ------------------------------ WEB POSTSCould giant underwater curtains slow ice-sheet melting? <https://www.nature.com/articles/d41586-024-00119-3> (Nature)Make Sunsets Monthly 9,036 Ton-Years <https://makesunsets.com/blogs/news/make-sunsets-monthly-9-036-ton-years> (Make Sunsets) ------------------------------ BOOK CHAPTERGeoengineering and Public Policy—Routledge Handbook of Environmental Policy <http://edepot.wur.nl/634326> ------------------------------ POLICY DIGESTA New Era of Policy in Solar Geoengineering <https://kleinmanenergy.upenn.edu/research/publications/a-new-era-of-policy-in-solar-geoengineering/> <https://kleinmanenergy.upenn.edu/research/publications/a-new-era-of-policy-in-solar-geoengineering/> ------------------------------ JOB OPPORTUNITYUCL Earth Sciences PhD Scholarship | Deadline: 05 February 2024 <https://www.ucl.ac.uk/earth-sciences/news/2023/dec/ucl-earth-sciences-phd-scholarship> *“If you're from an under-represented group and would like to work on an under-represented field, you could apply to do a PhD on Solar Geoengineering & various other topics.”* ------------------------------ UPCOMING EVENTS(NEW) Solar radiation modification in the United States: a discussion by Climate Overshoot Commission <https://mailchi.mp/overshootcommission/climate-overshoot-commission-press-conference-invite-12660642?e=da98907665> | 24 January 2024(NEW) Researching Solar Geoengineering: A Necessary Climate Approach or Dangerous Distraction by Harvard John A. Paulson School of Engineering and Applied Sciences <https://events.seas.harvard.edu/event/researching_solar_geoengineering_a_necessary_climate_approach_or_dangerous_distraction> | 26 January 2024(NEW) Gideon Futerman on SRM and Global Catastrophic Risk bu HPAC <https://us02web.zoom.us/j/88954851189?pwd=WVZoeTBnN3kyZFoyLzYxZ1JNbDFPUT09> | 08 February 2024*104th Annual Meeting by American Meteorological Society <https://ams.confex.com/ams/104ANNUAL/meetingapp.cgi/Program/1743> | 28 January 2024 - 01 February 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* ------------------------------ PODCASTSBlocking the Sun Is NOT a Climate Solution! | Organic Consumer Association <https://www.spreaker.com/episode/blocking-the-sun-is-not-a-climate-solution--56142166> *“[W]hen you start to reflect light away from the planet, you can easily imagine a chain of events that would extinguish life on earth.”**That’s what David Keith, one of the world’s top solar engineering scientists, told the New Yorker about his own life’s work.**With a warning like that, it’s easy to see why Mexico is banning solar geoengineering. That, and the fact that a start-up called “Make Sunsets” was caught trying to block the sun in Baja California Sur—without permission from, or even notifying, the government!**Moving in the other direction, the Biden Administration is officially exploring ways to stop sunlight from reaching the Earth, while the European Union has recently floated “a potential international framework” for going forward with research into this misguided and ineffective attempt to address the global climate crisis.**Few policy makers in the U.S. have tried to wrap their heads around this issue, but a group of Rhode Island state legislators have drafted a bill, the Atmosphere Protection Act that’s a great introduction.”* ------------------------------ YOUTUBE VIDEOSLeon Simons: "Aerosol Demasking and Global Heating" | The Great Simplification #105 <https://www.youtube.com/hashtag/105> | Nate Hagens <https://www.youtube.com/watch?v=RPAnoSt6FnY> *“On this episode, Nate is joined by climate researcher Leon Simons to unpack recent trends in global heating during 2023 and potential explanations and subsequent projections for the coming year. While the connection between human emitted greenhouse gasses and global warming is scientifically agreed upon, the other complexities and feedbacks of our climate system are still just beginning to be understood. Today, Leon theorizes on the intensity of aerosol masking from particulates such as sulfur, based on the connection between recent changes in marine fuel sulfur requirements and corresponding climate data. How will the global trend towards aerosol reductions affect near and long term global heating? What does this catch-22 mean for potential future climate action and policy? How should we be thinking about creating a more simplified global system in response to the unknown unknowns of our potential future climate?”* *Revolution Wrap-Up: Conclusion & Next Steps | Roger Hallam* <https://www.youtube.com/watch?v=yybxae3DYj8>Can solar geoengineering help undo climate change? | The State of Knowledge <https://www.youtube.com/watch?v=y5x33DbGUOI> *“One of the more controversial solutions to the effects of the climate crisis is geoengineering, that is according to Harvard’s geoengineering research program, ‘a set of emerging technologies that could manipulate the environment and partially offset some of the impacts of climate change’. But what is the field's current state?”* Geoengineering: Who Should Control Our Atmosphere? | Climate One <https://www.youtube.com/watch?v=iCgWwv1Hu_o> *“According to the latest IPCC Assessment Report, we’re currently on course for at least 3°C (5.4°F) of warming by 2100 even if all of the voluntary Paris Agreement emissions pledges are fulfilled. Clearly the world needs to do more to reduce emissions. But what if that’s still not enough?”* ------------------------------ *DEADLINES**Call for Papers: Special Collection-Towards a Risk-Risk-Assessment of Solar Radiation Modification <https://academic.oup.com/oocc/pages/solar-radiation-modification?login=false> | Deadline for manuscript submissions: 31 May 2024**The Climate Intervention Environmental Impact Fund (CIEIF) announced another round of three grants for the first half of 2024 with increased award amounts of $65,000 each <https://cieif.org/new-global-climate-restoration-fund-announces-first-grant-cycle/> | Application Deadline: 01 June 2024* ------------------------------ -- 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]. 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