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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 PAPERSA protocol for model intercomparison of impacts of Marine Cloud Brightening Climate Intervention <https://egusphere.copernicus.org/preprints/2024/egusphere-2024-1031/> Rasch, P., Hirasawa, H., Wu, M., Doherty, S., Wood, R., Wang, H., ... & Singh, H. (2024). A protocol for model intercomparison of impacts of Marine Cloud Brightening Climate Intervention. *EGUsphere*, *2024*, 1-43. *Abstract* A modeling protocol is introduced (defined by a series of model simulations with specified model output). The protocol is designed to improve understanding of climate impacts from Marine Cloud Brightening (MCB) Climate Intervention. The model simulations are not intended to assess consequences from a realistic MCB deployment intended to achieve specific climate targets but instead to expose responses produced by MCB interventions in 6 regions with pervasive cloud systems that are often considered as candidate regions for such a deployment. A calibration step involving simulations with fixed sea surface temperatures is first used to identify a common forcing, and then coupled simulations with forcing in individual regions and combinations of regions are used to examine climate impacts. Synthetic estimates constructed by superposing responses from simulations with forcing in individual regions are considered as a means to approximate the climate impacts produced when MCB interventions are introduced in multiple regions. A few results comparing simulations from 3 modern climate models (CESM2, E3SMv2, UKESM1) are used to illustrate similarities and differences between model behavior and the utility of estimates of MCB climate responses that have been synthesized by summing responses introduced in individual regions. There are substantial differences in the cloud responses to aerosol injections between models, but the models often show strong similarities in precipitation and surface temperature response signatures when forcing is imposed with similar amplitudes in common regions. Shedding light on the increased carbon uptake by a boreal forest under diffuse solar radiation across multiple scales <https://pubmed.ncbi.nlm.nih.gov/38624252/> Neimane‐Šroma, S., Durand, M., Lintunen, A., Aalto, J., & Robson, T. M. (2024). Shedding light on the increased carbon uptake by a boreal forest under diffuse solar radiation across multiple scales. *Global Change Biology*, *30*(4), e17275. *Abstract* Solar radiation is scattered by cloud cover, aerosols and other particles in the atmosphere, all of which are affected by global changes. Furthermore, the diffuse fraction of solar radiation is increased by more frequent forest fires and likewise would be if climate interventions such as stratospheric aerosol injection were adopted. Forest ecosystem studies predict that an increase in diffuse radiation would result in higher productivity, but ecophysiological data are required to identify the processes responsible within the forest canopy. In our study, the response of a boreal forest to direct, diffuse and heterogeneous solar radiation conditions was examined during the daytime in the growing season to determine how carbon uptake is affected by radiation conditions at different scales. A 10-year data set of ecosystem, shoot and forest floor vegetation carbon and water-flux data was examined. Ecosystem-level carbon assimilation was higher under diffuse radiation conditions in comparison with direct radiation conditions at equivalent total photosynthetically active radiation (PAR). This was driven by both an increase in shoot and forest floor vegetation photosynthetic rate. Most notably, ecosystem-scale productivity was strongly related to the absolute amount of diffuse PAR, since it integrates both changes in total PAR and diffuse fraction. This finding provides a gateway to explore the processes by which absolute diffuse PAR enhances productivity, and the long-term persistence of this effect under scenarios of higher global diffuse radiation. Speed of environmental change frames relative ecological risk in climate change and climate intervention scenarios <https://www.nature.com/articles/s41467-024-47656-z> Hueholt, D. M., Barnes, E. A., Hurrell, J. W., & Morrison, A. L. (2024). Speed of environmental change frames relative ecological risk in climate change and climate intervention scenarios. *Nature Communications*, *15*(1), 3332. *Abstract* Stratospheric aerosol injection is a potential method of climate intervention to reduce climate risk as decarbonization efforts continue. However, possible ecosystem impacts from the strategic design of hypothetical intervention scenarios are poorly understood. Two recent Earth system model simulations depict policy-relevant stratospheric aerosol injection scenarios with similar global temperature targets, but a 10-year delay in intervention deployment. Here we show this delay leads to distinct ecological risk profiles through climate speeds, which describe the rate of movement of thermal conditions. On a planetary scale, climate speeds in the simulation where the intervention maintains temperature are not statistically distinguishable from preindustrial conditions. In contrast, rapid temperature reduction following delayed deployment produces climate speeds over land beyond either a preindustrial baseline or no-intervention climate change with present policy. The area exposed to threshold climate speeds places different scenarios in context to their relative ecological risks. Our results support discussion of tradeoffs and timescales in future scenario design and decision-making. Regional Welfare Impacts from Options for Limiting Global Average Temperature <https://www.researchsquare.com/article/rs-4009794/v1> Ding, C., Kim, S., Singer, C., & Sriver, R. (2024). Regional Welfare Impacts from Options for Limiting Global Average Temperature. *Abstract* Extrapolation of historical trends in anthropogenic atmospheric carbon dioxide emissions is compared to results with new policy options. One approach is to multiply historical extrapolation of global emissions by a factor with a decline from 1 to a smaller multiple, e.g. on a timescale of about 30 years. Another allows for solar radiation management via anthropogenic stratospheric sulfur injection by one or more of sixteen geographic regions, in order to limit global average temperature to a chosen target level. An economic measure of impacts on human welfare is compared for different versions of these two approaches. That measure is time-integrated discounted utility of per capita consumption. That measure is computed with and without empathy, which involves geographical regions counting part of others’ welfare as part of their own. Inter-regional fund transfers that cover all or part of a region’s expenditures used for limiting carbon emissions can be used to encourage broader inter-regional cooperation. These exercises pose interesting questions about how choices will ultimately be made between use of one or both of carbon emissions limitations and solar radiation management. A fully coupled solid particle microphysics scheme for stratospheric aerosol injections within the aerosol-chemistry-climate-model SOCOL-AERv2 <https://egusphere.copernicus.org/preprints/2024/egusphere-2024-444/> Vattioni, S., Weber, R., Feinberg, A., Stenke, A., Dykema, J. A., Luo, B., ... & Chiodo, G. (2024). A fully coupled solid particle microphysics scheme for stratospheric aerosol injections within the aerosol-chemistry-climate-model SOCOL-AERv2. *EGUsphere*, *2024*, 1-41. *Abstract* Recent studies have suggested that injection of solid particles such as alumina and calcite particles for stratospheric aerosol injection (SAI) instead of sulfur-based injections could reduce some of the adverse side effects of SAI such as ozone depletion and stratospheric heating. Here, we present a version of the global aerosol-chemistry-climate model SOCOL-AERv2 and the Earth System Model (ESM) SOCOLv4 which incorporate a solid particle microphysics scheme for assessment of SAI of solid particles. Microphysical interactions of the solid particle with the stratospheric sulfur cycle were interactively coupled to the heterogeneous chemistry scheme and the radiative transfer code (RTC) for the first time within an ESM. Therefore, the model allows simulation of heterogeneous chemistry at the particle surface as well as feedbacks between microphysics, chemistry, radiation and climate. We show that sulfur-based SAI results in a doubling of the stratospheric aerosol burden compared to the same injection rate of calcite and alumina particles with radius of 240 nm, mainly due to the smaller density and the smaller average particle size of sulfuric acid aerosols and thus, slower sedimentation. Therefore, to achieve the same radiative forcing, larger injection rates are needed for calcite and alumina particle injection than for sulfur-based SAI. The stratospheric sulfur cycle would be significantly perturbed, with a reduction in stratospheric sulfuric acid burden by 53 %, when injecting 5 Mt/yr of alumina or calcite particles of 240 nm radius. We show that alumina particles will acquire a sulfuric acid coating equivalent of about 10 nm thickness, if the sulfuric acid is equally distributed over the whole available particle surface area in the lower stratosphere. However, due to a steep contact angle of sulfuric acid on alumina particles, the sulfuric acid coating would likely not cover the entire alumina surface, which would result in available surface for heterogeneous reactions other than the ones on sulfuric acid. When applying realistic uptake coefficients of 1.0, 10-5 and 10-4 for H2SO4, HCl and HNO3, respectively, the same scenario with injections of calcite particles results in 94 % of the particle mass remaining in the form of CaCO3. This likely keeps the optical properties of the calcite particles intact, but could significantly alter the heterogeneous reactions occurring on the particle surfaces. The major process uncertainties of solid particle SAI are 1) the solid particle microphysics in the injection plume and degree of agglomeration of solid particles on the sub-ESM grid scale, 2) the scattering properties of the resulting agglomerates 3) heterogeneous chemistry on the particle surface and 4) aerosol-cloud interactions. These uncertainties can only be addressed with extensive, coordinated, experimental and modelling research efforts. The model presented in this work offers a useful tool for sensitivity studies and impact analysis of new experimental results on points 1) to 3) for SAI of solid particles. Possible Mitigation of Global Cooling due to Supervolcanic Eruption via Intentional Release of Fluorinated Gases <https://essopenarchive.org/users/540715/articles/642445-possible-mitigation-of-global-cooling-due-to-supervolcanic-eruption-via-intentional-release-of-fluorinated-gases> Xu, Y., Ribar, N. P., Schade, G. W., Lockley, A. J., Zhang, Y. G., Sachnik, J., ... & Velders, G. J. (2023). Possible Mitigation of Global Cooling due to Supervolcanic Eruption via Intentional Release of Fluorinated Gases. *Authorea Preprints*. *Abstract* Supervolcanic eruptions induced abrupt global cooling (roughly at a rate of ~1ºC/year lasting for years to decades), such as the prehistoric Yellowstone eruption released, by some estimates, SO2 about 100 times higher than the 1991 Mt. Pinatubo eruption. An abrupt global cooling of several ºC, even if only lasting a few years, would present immediate and drastic stress on biodiversity and food production - posing a global catastrophic risk to human society. Using a simple climate model, this paper discusses the possibility of counteracting supervolcanic cooling with the intentional release of greenhouse gases. Although well-known longer-lived compounds such as CO2 and CH₄ are found to be unsuitable for this purpose, select fluorinated gases (F-gases), either individually or in combinations, may be released at gigaton scale to offset most of the supervolcanic cooling. We identify candidate F-gases (viz. C4F6 and CH3F) and derive radiative and chemical properties of ‘ideal’ compounds matching specific cooling events. Geophysical constraints on manufacturing and stockpiling due to mineral availability are considered alongside technical and economic implications based on present-day market assumptions. The consequences of F-gas release in perturbing atmospheric chemistry are discussed in the context of those due to the supervolcanic eruption itself. The conceptual analysis here suggests the possibility of mitigating certain global catastrophic risks via intentional intervention. ------------------------------ WEB POSTSLet’s talk about geoengineering! <https://www.linkedin.com/pulse/lets-talk-geoengineering-tamas-bodai-mynyf> (LinkedIn)Why We Need To Share Knowledge With Young People On The Ground: Lessons Learned From Nairobi And Mombasa <https://sgdeliberation.org/why-we-need-to-share-knowledge-with-young-people-on-the-ground-lessons-learned-from-nairobi-and-mombasa/> (DSG)Startups want to geoengineer a cooler planet. With few rules, experts see big risks <https://www.npr.org/2024/04/21/1244357506/earth-day-solar-geoengineering-climate-make-sunsets-stardust> (NPR) <https://www.npr.org/2024/04/21/1244357506/earth-day-solar-geoengineering-climate-make-sunsets-stardust> ------------------------------ *UPCOMING EVENTS**(NEW) Dr Alan Gadian on Marine Cloud Brightening by HPAC <https://groups.google.com/g/geoengineering/c/h0FQLRf9T3g> | 29 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%2F0fefc5de-0166-413e-aefb-3d1d069a0c72_720x597.jpeg> Solar Geoengineering Events Calendar <https://teamup.com/ks64mmvtit583eitxx> ------------------------------ PODCASTSAI and international conflict - Morrissey | Reviewer 2 does geoengineering SAI and international conflict - Morrissey Reviewer 2 does geoengineering 1:24:52 <https://podcasts.apple.com/us/podcast/sai-and-international-conflict-morrissey/id1529459393?i=1000652616830&uo=4> "William Morrissey explains how SAI could lead to conflict and counter-geoengineering. @geoengineering1 isn't convinced it will all end so badly. Avoiding atmospheric anarchy: Geoengineering as a source of interstate tension —William Morrissey https://doi.org/10.1177/27538796231221597"; ------------------------------ YOUTUBE VIDEOPlaying God? Weather Change Experiments in San Francisco | CBN News <https://www.youtube.com/watch?v=0vR2xcdu5Ac> "What are the consequences of this? Potentially catastrophic." Scientists onboard a decommissioned aircraft carrier are conducting marine cloud brightening experiments hoping to stop global warming. The CO2 Coalition's Greg Wrightstone says first, the scientists must consider the Hippocratic oath to "do no harm." -- 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/CAHJsh98PKUbdv%2BZxoCo9HPmRwu_Mf0-gJfcHXDL-UjY_sNNmRA%40mail.gmail.com.
