SOLAR GEOENGINEERING WEEKLY SUMMARY (08 APRIL - 14 APRIL 2024) Subscribe to our newsletter to receive monthly updates on Solar Geoengineering: Solar Geoengineering Updates <https://solargeoengineeringupdates.substack.com?utm_source=substack&utm_campaign=publication_embed&utm_medium=email> Monthly news summaries about solar geoengineering. Links to scientific papers, news articles, jobs, podcasts, and videos. <https://solargeoengineeringupdates.substack.com?utm_source=substack&utm_campaign=publication_embed&utm_medium=email> By Andrew Lockley <https://solargeoengineeringupdates.substack.com?utm_source=substack&utm_campaign=publication_embed&utm_medium=email> ------------------------------ RESEARCH PAPERSSubstantial cooling effect from aerosol-induced increase in tropical marine cloud cover <https://www.nature.com/articles/s41561-024-01427-z>
Chen, Y., Haywood, J., Wang, Y., Malavelle, F., Jordan, G., Peace, A., ... & Lohmann, U. (2024). Substantial cooling effect from aerosol-induced increase in tropical marine cloud cover. *Nature Geoscience*, 1-7. *Abstract* With global warming currently standing at approximately +1.2 °C since pre-industrial times, climate change is a pressing global issue. Marine cloud brightening is one proposed method to tackle warming through injecting aerosols into marine clouds to enhance their reflectivity and thereby planetary albedo. However, because it is unclear how aerosols influence clouds, especially cloud cover, both climate projections and the effectiveness of marine cloud brightening remain uncertain. Here we use satellite observations of volcanic eruptions in Hawaii to quantify the aerosol fingerprint on tropical marine clouds. We observe a large enhancement in reflected sunlight, mainly due to an aerosol-induced increase in cloud cover. This observed strong negative aerosol forcing suggests that the current level of global warming is driven by a weaker net radiative forcing than previously thought, arising from the competing effects of greenhouse gases and aerosols. This implies a greater sensitivity of Earth’s climate to radiative forcing and therefore a larger warming response to both rising greenhouse gas concentrations and reductions in atmospheric aerosols due to air quality measures. However, our findings also indicate that mitigation of global warming via marine cloud brightening is plausible and is most effective in humid and stable conditions in the tropics where solar radiation is strong. G6-1.5K-SAI: a new Geoengineering Model Intercomparison Project (GeoMIP) experiment integrating recent advances in solar radiation modification studies <https://gmd.copernicus.org/articles/17/2583/2024/> Visioni, D., Robock, A., Haywood, J., Henry, M., Tilmes, S., MacMartin, D. G., ... & Egbebiyi, T. S. (2023). G6-1.5 K-SAI: a new Geoengineering Model Intercomparison Project (GeoMIP) experiment integrating recent advances in solar radiation modification studies. *EGUsphere*, *2023*, 1-21. *Abstract* The Geoengineering Model Intercomparison Project (GeoMIP) has proposed multiple model experiments during phases 5 and 6 of the Climate Model Intercomparison Project (CMIP), with the latest set of model experiments proposed in 2015. With phase 7 of CMIP in preparation and with multiple efforts ongoing to better explore the potential space of outcomes for different solar radiation modifications (SRMs) both in terms of deployment strategies and scenarios and in terms of potential impacts, the GeoMIP community has identified the need to propose and conduct a new experiment that could serve as a bridge between past iterations and future CMIP7 experiments. Here we report the details of such a proposed experiment, named G6-1.5K-SAI, to be conducted with the current generation of scenarios and models from CMIP6 and clarify the reasoning behind many of the new choices introduced. Namely, compared to the CMIP6 GeoMIP scenario G6sulfur, we decided on (1) an intermediate emission scenario as a baseline (the Shared Socioeconomic Pathway 2-4.5), (2) a start date set in the future that includes both considerations for the likelihood of exceeding 1.5 °C above preindustrial levels and some considerations for a likely start date for an SRM implementation, and (3) a deployment strategy for stratospheric aerosol injection that does not inject in the tropical pipe in order to obtain a more latitudinally uniform aerosol distribution. We also offer more details regarding the preferred experiment length and number of ensemble members and include potential options for second-tier experiments that some modeling groups might want to run. The specifics of the proposed experiment will further allow for a more direct comparison between results obtained from CMIP6 models and those obtained from future. Climate engineering by Passive daytime radiative cooling: Moving beyond materials towards real-world applications <https://doi.org/10.1016/j.nxener.2024.100121> Aili, A., Jiang, T., Chen, J., Wen, Y., Yang, R., Yin, X., & Tan, G. (2024). Passive daytime radiative cooling: Moving beyond materials towards real-world applications. *Next Energy*, *3*, 100121. *Abstract* Passive daytime radiative cooling has emerged as a promising sustainable technique for meeting ever-growing demand for cooling across multiple sectors. Although a number of review articles have reported fundamental mechanisms and materials developments of daytime radiative cooling, reviews on its current and potential applications have been limited to specific scenarios such as building energy saving. Thus, to the best of our knowledge, here we summarize and discuss a comprehensive list of most current and potential applications of passive daytime radiative cooling to broaden horizons in this technology. First, from a materials perspective, we briefly summarize approaches to creating high solar reflectance and high emissivity in the atmospheric window of 8–13 µm. We then present applications in five major categories, each with several sub-categories, and discus each application with selective articles. Based on the availability of real-world demonstrations and developments in commercialization, we qualitatively assess the technology readiness levels of these applications, highlighting future directions that need more attention. This review offers one-stop access to a comprehensive summary of passive radiative cooling applications along with recent progress and future opportunities. Rethinking the susceptibility-based strategy for marine cloud brightening climate intervention: experiment with CESM2 and its implications <https://essopenarchive.org/doi/full/10.22541/essoar.171201044.45268441/v1> Chen, C. C., Richter, J. H., Lee, W., MacMartin, D. G., & Kravitz, B. (2024). Rethinking the susceptibility-based strategy for marine cloud brightening climate intervention: experiment with CESM2 and its implications. *Authorea Preprints*. *Abstract* Previous modeling studies indicate that even though marine cloud brightening under a susceptibility-based strategy is effective in reducing the global average surface temperature, it triggers a La Niña-like sea-surface temperature response with cooling mostly confined within lower latitudes. Here we explore a different cloud seeding strategy involving seeding of regions with low susceptibility. Simulations with the Community Earth System Model, version 2 (CESM2) reveal that because the regional forcing is weaker and more widespread, cooling is more evenly distributed over the globe. This new strategy also does not result in the La Niña-like state seen in the other strategies. Moral hazards and solar radiation management: Evidence from a large-scale online experiment <https://www.sciencedirect.com/science/article/pii/S0272494424000616> Schoenegger, P., & Mintz-Woo, K. (2024). Moral hazards and solar radiation management: Evidence from a large-scale online experiment. *Journal of Environmental Psychology*, 102288. *Abstract* Solar radiation management (SRM) may help to reduce the negative outcomes of climate change by minimising or reversing global warming. However, many express the worry that SRM may pose a moral hazard, i.e., that information about SRM may lead to a reduction in climate change mitigation efforts. In this paper, we report a large-scale preregistered, money-incentivised, online experiment with a representative US sample (N = 2284). We compare actual behaviour (donations to climate change charities and clicks on climate change petition links) as well as stated preferences (support for a carbon tax and self-reported intentions to reduce emissions) between participants who receive information about SRM with two control groups (a salience control that includes information about climate change generally and a content control that includes information about a different topic). Behavioural choices are made with an earned real-money endowment, and stated preference responses are incentivised via the Bayesian Truth Serum. We fail to find a significant impact of receiving information about SRM and, based on equivalence tests, we provide evidence in favour of the absence of a meaningfully large effect. Our results thus provide evidence for the claim that there is no detectable moral hazard with respect to SRM. Australia, we need to talk about solar geoengineering <https://www.tandfonline.com/doi/full/10.1080/10357718.2024.2333811> Symons, J., Fung, C., Jayaram, D., Kabbej, S., & McDonald, M. (2024). Australia, we need to talk about solar geoengineering. *Australian Journal of International Affairs*, 1-6. *Abstract* Solar geoengineering is a deeply controversial idea. It is now well understood that growing atmospheric concentrations of greenhouse gases have placed the global climate in a perilous and unprecedented situation. Solar geoengineering is either a dangerous distraction from the urgent work of decarbonising economic process, or possibly a flawed, imperfect and partial response that might limit climate harms while the international community gets serious about urgent mitigation action. While Australia and its neighbours are among the most climate-vulnerable countries, they are currently among the least informed about the possible consequences of solar geoengineering. Australian climate scientists are well represented among scholars modelling solar geoengineering scenarios. However, to date there has been no effort to detail implications for Australia. Regardless of whether Australia and its Pacific neighbours ultimately support or oppose climate interventions, Australian policy-makers and researchers need to start taking the potential implications and governance of solar geoengineering seriously. Side Effects of Sulfur-Based Geoengineering Due To Absorptivity of Sulfate Aerosols <https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023GL107285> Wunderlin, E., Chiodo, G., Sukhodolov, T., Vattioni, S., Visioni, D., & Tilmes, S. (2024). Side effects of sulfur‐based geoengineering due to absorptivity of sulfate aerosols. *Geophysical Research Letters*, *51*(4), e2023GL107285. *Abstract* Sulfur-based stratospheric aerosol intervention (SAI) can cool the climate, but also heats the tropical lower stratosphere if done with injections at low latitudes. We explore the role of this heating in the climate response to SAI, by using mechanistic experiments that remove the effects of longwave absorption of sulfate aerosols above the tropopause. If longwave absorption by stratospheric aerosols is disabled, the heating of the tropical tropopause and most of the related side effects are strongly alleviated and the cooling per Tg-S injected is 40% bigger. Such side-effects include the poleward expansion of eddy-driven jets, acceleration of the stratospheric residual circulation, and delay of Antarctic ozone recovery. Our results add to other recent findings on SAI side effects and demonstrate that SAI scenarios with low-latitude injections of absorptive materials may result in atmospheric effects and regional climate changes that are comparable to those produced by the CO2 warming signal. Solar Geoengineering, Free-Driving and Conflict: An Experimental Investigation <https://link.springer.com/article/10.1007/s10640-024-00854-1> Cherry, T. L., Kroll, S., McEvoy, D. M., & Campoverde, D. (2024). Solar Geoengineering, Free-Driving and Conflict: An Experimental Investigation. *Environmental and Resource Economics*, 1-16. *Abstract* As the international community continues to fall short on reducing emissions to avoid disastrous impacts of climate change, some scientists have called for more research into solar geoengineering (SGE) as a potential temporary fix. Others, however, have adamantly rejected the notion of considering SGE in climate policy discussions. One prominent concern with considering SGE technologies to help manage climate change is the so-called “free driver” conjecture. The prediction is that among countries with different preferences for the level of SGE, the country that prefers the most will deploy levels higher than the global optimum. This paper tests the free-driver hypothesis experimentally under different conditions and institutions. We find that aggregate deployment of SGE is inefficiently high in all settings, but slightly less so when players are heterogeneous in endowments or when aggregate deployment is determined by a best-shot technology. Despite persistent inefficiencies in SGE deployment, free-driver behavior, on average, is less extreme than the theoretical predictions. <https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F3eae9bd3-b0cb-45d9-97e3-7ba6d29c1940_2497x1287.png> Visioni, D., Robock, A., Haywood, J., Henry, M., Tilmes, S., MacMartin, D. G., ... & Egbebiyi, T. S. (2023). G6-1.5 K-SAI: a new Geoengineering Model Intercomparison Project (GeoMIP) experiment integrating recent advances in solar radiation modification studies. <https://gmd.copernicus.org/articles/17/2583/2024/>*EGUsphere <https://gmd.copernicus.org/articles/17/2583/2024/>*, <https://gmd.copernicus.org/articles/17/2583/2024/>*2023 <https://gmd.copernicus.org/articles/17/2583/2024/>*, 1-21. <https://gmd.copernicus.org/articles/17/2583/2024/> [image: figure 4] <https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fe38c9c41-6565-41f8-98c8-5744833b2414_685x424.png> Chen, Y., Haywood, J., Wang, Y., Malavelle, F., Jordan, G., Peace, A., ... & Lohmann, U. (2024). Substantial cooling effect from aerosol-induced increase in tropical marine cloud cover. <https://www.nature.com/articles/s41561-024-01427-z>*Nature Geoscience <https://www.nature.com/articles/s41561-024-01427-z>*, 1-7. <https://www.nature.com/articles/s41561-024-01427-z> <https://www.sciencedirect.com/science/article/pii/S2949821X24000267?via%3Dihub#fig0010> [image: Image 1] <https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F79a27398-b7a7-424e-9743-4f8a81126078_732x708.jpeg> Aili, A., Jiang, T., Chen, J., Wen, Y., Yang, R., Yin, X., & Tan, G. (2024). Passive daytime radiative cooling: Moving beyond materials towards real-world applications. <https://www.sciencedirect.com/science/article/pii/S2949821X24000267?via%3Dihub#fig0010>*Next Energy <https://www.sciencedirect.com/science/article/pii/S2949821X24000267?via%3Dihub#fig0010>*, <https://www.sciencedirect.com/science/article/pii/S2949821X24000267?via%3Dihub#fig0010>*3 <https://www.sciencedirect.com/science/article/pii/S2949821X24000267?via%3Dihub#fig0010>*, 100121. <https://www.sciencedirect.com/science/article/pii/S2949821X24000267?via%3Dihub#fig0010> ------------------------------ WEB POSTSThe inadvertent geoengineering experiment that the world is now shutting off <https://www.technologyreview.com/2024/04/11/1091087/the-inadvertent-geoengineering-experiment-that-the-world-is-now-shutting-off/> (MIT Technology Review)What values do SRM researchers share? (Plan A+) Plan A+ What values do SRM researchers share? <https://peteirvine.substack.com/p/what-values-do-srm-researchers-share?utm_source=substack&utm_campaign=post_embed&utm_medium=email> What motivates researchers studying SRM and what values do they bring to their work? There are different kinds of researchers with different kinds of motivations working on SRM, but here I’ll focus on what I consider to be mainstream SRM scientists. These are researchers, like myself, who are working to develop an evidence base on which future decisions… Read more <https://peteirvine.substack.com/p/what-values-do-srm-researchers-share?utm_source=substack&utm_campaign=post_embed&utm_medium=email> 5 days ago · 2 likes · 1 comment · Pete Irvine Staring at the Sun <https://www.epfl.ch/schools/cdh/alice-bucknell-staring-at-the-sun/> (EPFL) "Staring at the Sun is a research project and multimedia “sci-fi documentary” that’s rooted within an urgent unfolding dialogue around planetary-scale climate modification projects. Toggling across scales, political agendas, technologies, and temporalities, it aims to critically examine contemporary solar geoengineering proposals including stratospheric aerosol injection (SAI) that are currently undergoing research development in both the United States and the European Union." ------------------------------ *UPCOMING EVENTS*(NEW) Dr Alan Gadian on Marine Cloud Brightening by HPAC <https://groups.google.com/g/geoengineering/c/G8Q1jYlj7d0> | 18 April 2024*Solar Radiation Modification, Clouds, Aerosols, and their Impacts on the Biosphere and Earth System | EGU General Assembly <https://meetingorganizer.copernicus.org/EGU24/session/49142> | 18 April 2024**Fourteenth GeoMIP Workshop | Ithaca, USA <https://climate.envsci.rutgers.edu/GeoMIP/2024.html> | 10-12 July 2024* Solar Geoengineering Events Calendar <https://teamup.com/ks64mmvtit583eitxx> *GUIDELINES:**Sync selected events to your default calendar in these simple steps:**1) Click on the event you want to sync.**2) Tap the menu icon (three vertical lines) at the top left.**3) Choose 'Share.'**4) Pick your default calendar.**5) Save the event.* *Sync the entire Teamup Calendar to your default calendar with these simple steps:**1) Tap the menu icon (three vertical lines) at the top right.**2) Choose 'Preferences.'**3) Click 'iCalendar Feeds.'**4) Copy the URL shown for 'Solar Geoengineering Events / SRM Deadlines.'’**5) Paste the URL into your default calendar settings (Open Google Calendar in your web browser if you are using Gcal).**6) Click 'Subscribe' or 'Add Calendar.'* *For more detailed instructions, visit: https://calendar.teamup.com/kb/subscribe-to-teamup-icalendar-feeds/ <https://calendar.teamup.com/kb/subscribe-to-teamup-icalendar-feeds/>* *You can directly sync all Solar Geoengineering events to your default calendars by pressing the link below:* Sync SG Events to your Default Calendar <https://ics.teamup.com/feed/ks64mmvtit583eitxx/0.ics> <https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2Fd7600ecb-75e0-42fd-9fb0-b3e9614a6b08_720x597.jpeg> Solar Geoengineering Events Calendar <https://teamup.com/ks64mmvtit583eitxx> ------------------------------ *DEADLINES*(NEW) DSG's Early Career Researchers Network <https://docs.google.com/forms/d/e/1FAIpQLSfrW3sFDl7XjJ3jB6oMEMj2CBTfAPHQSklnAbnDeU_1quwYHQ/viewform> | Survey Closes on 19 April 2024 "DSG’s Youth Engagement program seeks to provide young people, especially those from climate-vulnerable regions, with access to diverse and science-based information to enable constructive engagement in deliberation about solar geoengineering. Their first step in building the Early Career Researchers Network is to understand how it would be most useful to young researchers. To that end, they’ve developed a survey to gather information on ideas and needs." ------------------------------ YOUTUBE VIDEOSSandro Vattioni: Risks and benefits of climate intervention via stratospheric aerosol injection | NCAR Atmospheric Chemistry Observations & Modeling <https://www.youtube.com/watch?v=GaPhaqsqGrw> "Abstract: Recent studies have suggested that injection of solid particles such as alumina and calcite instead of SO2 for climate intervention via stratospheric aerosol injection (SAI) could reduce some of the adverse side effects of SAI such as ozone depletion and stratospheric heating. However, the expected improvements are subject to large uncertainties. We constrain some of these uncertainties by experimental work on calcite particles using elastic recoil detection analysis and in-situ X-ray photoelectron spectroscopy. Subsequently, we use a global aerosol-chemistry-climate model that, for the first time, interactively couples microphysical and chemical processes of solid particles as well as sulfuric acid aerosols with model radiation and transport. Notably, SAI by solid particles only leads to more effective radiative forcing per aerosol burden compared to sulfur-based SAI, not per injected mass. However, reduced stratospheric warming remains a major advantage of solid particles. Furthermore, different assumptions on the heterogeneous chemistry of solid particles, based on the available experimental data, result in drastically different impacts on stratospheric ozone layer. For alumina particles, which are thought to not undergo chemical aging in the stratosphere we present a sensitivity analysis of the ozone response to quantify uncertainty. For the alkaline calcite particles, which are thought to undergo chemical aging in the stratosphere via reaction with acids we find even larger uncertainties due to unknown reaction pathways and highly uncertain rates under stratospheric conditions. Uncertainty in predicted stratospheric ozone changes can only be reduced via additional laboratory experiments under stratospheric conditions." The USA's first solar geo-engineering test | The Laughington Post <https://www.youtube.com/watch?v=W6wvHo0M3c4> "The first outdoor test to limit global warming by increasing #cloud cover. The experiment, which organizers did not widely announce to avoid public backlash, marks the acceleration of a contentious field of research known as “solar radiation modification”. The concept involves shooting substances such as aerosols into the sky to reflect sunlight away from the Earth." Marine Cloud Brightening - Tribute to Stephen Salter | Climate Emergency Forum <https://www.youtube.com/watch?v=clYtK2tuCmU> "The Climate Emergency Forum hosts a discussion about the late Stephen Salter, a pioneering professor of engineering at the University of Edinburgh, and his work on marine cloud brightening (MCB) as a potential solution for mitigating global warming. This video was recorded on March 27th, 2024, and published on April 14th, 2024. The participants reflect on Salter's innovative ideas and creative mindset. A key focus is Salter's proposal to use a fleet of unmanned ships to spray fine sea water droplets into marine clouds to increase their reflectivity and albedo, thereby reflecting more sunlight back into space and cooling the planet. Salter provided calculations on the number of ships needed for different cooling goals, such as reversing sea level rise or preserving Arctic ice. The dialogue highlights the relatively low cost and scalability of this approach versus other geoengineering methods. The participants emphasize the need for solutions like MCB, given the rapidly worsening climate crisis. However, they also acknowledge the public opposition and lack of media coverage around such unconventional approaches. They stress the importance of engaging in broader conversations, good governance, and bringing the public on board through strategic communication efforts to explain the vision and overcome the code of silence around these topics in mainstream discourse. Overall, the dialogue serves as a tribute to Salter's innovative work while underscoring the potential of marine cloud brightening as a viable, affordable, and environmentally-friendly way to help mitigate global warming, if implemented responsibly and with proper public support." Can Mirrors on the Ground Cool the Earth? w/ Dr. Ye Tao, Founder of MEER.org | Climate Chat <https://www.youtube.com/watch?v=39kBw4UiN0o> "In this Climate Chat episode, we interview Dr. Ye Tao, the founder and Executive Director of MEER.org. MEER stands for "Mirrors for Earth's Energy Rebalancing." Dr. Tao proposes deploying mirrors on the ground (or oceans) to reflect sunlight back into space in order to reduce Earth's Energy Imbalance and cool the Earth. We will discuss the scale of mirrors needed to reverse the impacts of greenhouse gas warming as well as feasibility, cost, and side effects of implementing MEER. Besides full-scale deployment, Dr. Tao believes there are benefits to deploying smaller scale mirror systems. Dr. Tao also has interesting takes on other climate-related issues such as the side effects of renewable energy systems, low cost ways to implement Carbon Dioxide Removal (CDR), and the climate path we are on if we do not implement MEER or some other form of Sunlight Reflection Methods (SRM)." <https://carbonremovalupdates.substack.com/account> -- 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/CAHJsh9-1qoA_-jgyotd8TMR%3D5iE%3DmUSS%2BnWP3BqpKndNOPsT4Q%40mail.gmail.com.
