| SOLAR GEOENGINEERING WEEKLY SUMMARY (16 DECEMBER - 22 DECEMBER 2024) Subscribe to our newsletter to receive monthly updates on Solar Geoengineering:
RESEARCH PAPERSStefanetti, F., Vattioni, S., Dykema, J., Chiodo, G., Sedlacek, J., Keutsch, F., & Sukhodolov, T. (2024). Stratospheric injection of solid particles reduces side effects on circulation and climate compared to SO2 injections. Environmental Research: Climate. Abstract Most research of stratospheric aerosol injection (SAI) for solar radiation modification (SRM) has focused on injection of \ce{SO2}. However, the resulting sulfuric acid aerosols lead to considerable absorption of terrestrial infrared radiation, resulting in stratospheric warming and reduced cooling efficiency. Recent research suggests that solid particles, such as alumina, calcite or diamond, could minimize these side effects. Here we use, for the first time, the atmosphere-ocean-aerosol-chemistry-climate model SOCOLv4.0, incorporating a solid particle scheme, to assess the climatic impacts of SAI by these injection materials. For each substance, we model tropical SAI by means of constant yearly injection of solid particles, aimed to offset the warming induced by a high-GHG emission scenario over the 2020-2100 period by 1 K. We show that solid particles are more effective than sulfur at minimising stratospheric heating, and the resulting side-effects on the general atmospheric circulation, stratospheric moistening, and tropopause height change. As a result, solid particles also induce less residual warming over the Arctic, resulting in greater reduction of GHG-induced polar Amplification compared to sulfuric acid aerosols. Among the materials studied here, diamond is most efficient in reducing global warming per unit injection, while also minimizing side effects.
VanDeveer, S. D., Biermann, F., Kim, R. E., Bardi, C., & Gupta, A. Three Pathways to Nonuse Agreement (s) on Solar Geoengineering. Ethics & International Affairs, 1-12. Abstract Recent years have seen increasing calls by a few scientists, largely from the Global North, to explore “solar geoengineering,” a set of speculative technologies that would reflect parts of incoming sunlight back into space and, if deployed at planetary scale, have an average cooling effect. Numerous concerns about the development of such speculative technologies include the many ecological risks and uncertainties as well as unresolved questions of global governance and global justice. This essay starts with the premise that solar geoengineering at planetary scale is unlikely to be governable in a globally inclusive and just manner. Thus, the ethically sound approach is to pursue governance that leads to the nonuse of planetary solar geoengineering. Yet is such a prohibitory agreement feasible, in the face of possible opposition by a few powerful states and other interests? Drawing on social science research and a host of existing transnational and international governance arrangements, this essay offers three illustrative pathways through which a nonuse norm for solar geoengineering could emerge and become diffused and institutionalized in global politics: (1) civil society-led transnational approaches; (2) regionally led state and civil society hybrid approaches; and (3) like-minded or “Schengen-style” club initiatives led by states.
Harding, A., Vecchi, G. A., Yang, W., & Keith, D. W. (2024). Impact of solar geoengineering on temperature-attributable mortality. Proceedings of the National Academy of Sciences, 121(52), e2401801121. Abstract Decisions about solar geoengineering (SG) entail risk–risk tradeoffs between the direct risks of SG and SG’s ability to reduce climate risks. Quantitative comparisons between these risks are needed to inform public policy. We evaluate idealized SG’s effectiveness in reducing deaths from warming using two climate models and an econometric analysis of temperature-attributable mortality. We find SG’s impact on temperature-attributable mortality is uneven with decreases for hotter, poorer regions and increases in cooler, richer regions. Relative to no SG, global mortality is reduced by over 400,000 deaths annually [90% CI: (−1.2 million,2.7 million)] for cooling of 1 °C from 2.5 °C above preindustrial in 2080. We find no evidence that mortality reduction achieved by SG is smaller than the reduction from equivalent cooling by emissions reductions. Combining our estimates with existing estimates of sulphate aerosol injection direct mortality risk from air quality and UV-attributable cancer enables the first quantitative risk-risk comparison of SG. We estimate with 61% probability that the mortality benefits of cooling outweigh these direct SG risks. We find the benefits outweigh these risks by 13 times for our central estimates, or 4 deaths per 100,000 per 1 °C per year [90% CI: (−11,23)]. This is not a comprehensive evaluation of the risk–risk tradeoffs around SG, yet by comparing some of the most consequential impacts on human welfare it is a useful first step. While these findings are robust to a variety of alternative assumptions, considerable uncertainties remain and require further investigation.
Duffey, A., & Irvine, P. J. (2024). Accounting for transience in the baseline climate state changes the surface climate response attributed to stratospheric aerosol injection. Environmental Research: Climate. Abstract Stratospheric aerosol injection (SAI) is a proposed means of climate intervention that could halt global temperature rise, though it would imperfectly offset climate change. To estimate this imperfection, it is common to compare the simulated climate under SAI against that of a baseline state at the same global mean temperature without SAI. Here, we combine a recent set of SAI simulations (ARISE-SAI-1.5) in the earth system model UKESM1, with simulations of idealized abrupt and transient warming scenarios, to assess the impact of transient warming through this baseline state on surface climate changes attributed to SAI. We quantify the effect of temperature stabilisation as the expected change in surface climate between a climate state under warming and one in quasi-equilibrium at the same global mean temperature. We estimate that accounting for temperature stabilisation eliminates the land-sea warming ratio change attributed to SAI. However, relative to the hypothetical scenario with lower CO2 concentrations that would achieve a stabilised climate at the same temperature, SAI produces a 69% larger reduction in global precipitation. Accounting for stabilisation can also meaningfully change the spatial pattern of surface temperature response attributable to SAI. We repeat our analysis for the GeoMIP G6sulfur scenario, to show that effects qualitatively consistent with these findings are seen when comparing the SAI state against the faster and slower warming baselines of the SSP5-8.5 and SSP2-4.5 scenarios. The changes in climate state attributable to temperature stabilisation are generally small compared to changes due to warming since pre-industrial. However, these differences can be significant in the context of assessing residual changes under SAI because these residuals are themselves roughly an order of magnitude smaller than the effects of warming. Our findings have implications for the design and assessment of future SAI simulations, and for the attribution of changes in surface climate to SAI.
Oomen, J. Producing the Inevitability of Solar Radiation Modification in Climate Politics. Ethics & International Affairs, 1-15. Abstract This essay investigates the fit between solar radiation modification (SRM) and climate politics. Researchers, activists, and politicians often present SRM technologies as “radical.” According to this frame, SRM comes into view as a last-ditch effort to avoid climate emergencies. Such a rationale may be applicable to the scientists researching the potential of SRM, yet it only partially accounts for political and policy interest in SRM. In this contribution, I argue that there is an increasingly tight fit between the promise of SRM technologies and the global regime of climate politics. Within this regime, SRM may not be a radical option but is more of a logical extension of current rationales. I argue that SRM corresponds to tightly controlled discursive rules within which climate politics operates, leading to a shifting narrative on the feasibility, desirability, and necessity of SRM. The ethical implications of this tight fit are threefold. First, it implies that SRM might be an instrument of mitigation deterrence, implicitly as much as explicitly. Second, ethical responsibility and political value debates are at risk of becoming invisible once SRM becomes embedded in the prevailing regime. Third, SRM use might become inevitable, despite the good intentions of most people involved.
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THESISShahrasebi, M. (2024). Design, Development, and Evaluation of Splash-Plate Atomization for Marine Cloud Brightening (Doctoral dissertation, UNIVERSITY OF BRITISH COLUMBIA (Vancouver). Abstract Marine Cloud Brightening (MCB) has been proposed as a technique to produce local or regional cooling over remote oceans. The underlying principle of MCB is to artificially enhance the reflectivity and longevity of the maritime stratocumulus clouds by injecting seawater aerosols at low elevations (~ 1 km), where they act as cloud condensation nuclei. However, the presence of giant (1-10 microns) cloud condensation nuclei (CCN) within the seeded size spectrum expedites precipitation, which may break up the cloud layer. A critical challenge in MCB is the development of energy-efficient methods for generating and dispersing CCN of the optimal size range (30-500 nm). This thesis investigates the potential of splash-plate atomization (SPA) as a novel and efficient technique for MCB applications. SPA utilizes jet impingement on an inclined plate to generate a thin liquid sheet that subsequently breaks into droplets of a size comparable to the sheet thickness, rather than the orifice diameter, offering control over droplet size distribution. An experimental setup has been developed, including a SPA unit, a sampling room, and instrumentation for characterizing particle size distribution. To complement the aerosol size measurements, shadowgraph imaging has been performed, allowing for the visualization and analysis of the spray dynamics. The performance of the SPA system has been evaluated under various operating conditions, including different pumping pressures (1000, 1400, and 2000 psi), different spray deflection angles (75, 60, 45, and 30 degrees jet deflections), and different plate lengths (edgeproximal and edge-distant).
UPCOMING EVENTSSolar Geoengineering Events Calendar
PODCASTSNews Roundup: Live from the American Geophysical Union | Climate Reflections: The SRM360 Podcast | News Roundup: Live from the American Geophysical Union Climate Reflections: The SRM360 Podcast 30:46 |
"Host Pete Irvine is joined by SRM researchers Lili Xia, Chris Lennard, and Tyler Felgenhauer for a live recording from the American Geophysical Union conference in Washington D.C. They discuss the latest SRM news including: the New York Times article on U.S. efforts to develop an early warning system to detect SRM deployment; Florida senator Ileana Garcia's bill to ban all "weather modification" activities; takeaways from the UNFCCC COP related to SRM; the latest research on the impacts of SAI to human health; the European Commission's chief scientific advisory recommendations on SRM; and more!"
Simon Woods: Real Ice co-founder on the plan to re-freeze the Arctic | The Sunday Session with Francesca Rudkin"A UK-based startup is working on carrying out a bold plan to fix the decline of sea ice in the Arctic. Real Ice's ultimate plan is to re-freeze the Arctic by thickening ice to slow down the damage caused by climate change. Co-founder Simon Woods says this is their third winter of research - and it's promising so far. "We're chasing a moving target here - but at current levels, 1.2 meters of ice should survive the summer, and that's what we want."
Geoengineering through solar radiation modification - a last chance option? | TRACK CHANGES - climate change and sustainability interviews | Geoengineering through solar radiation modification - a last chance option? TRACK CHANGES - climate change and sustainability interviews 56:31 |
"There is no doubt that we have the means and the knowledge to rapidly decarbonise, reach net zero, and become net negative. But success is not guaranteed. If we falter over the coming years, could geoengineering through solar radiation modification be a last chance option? Might we reach the point where we need to cool the planet, to give us a bit more breathing space while we decarbonise? Is it possible, or is it too dangerous? Would it undermine efforts to rapidly decarbonise? Would the benefits outweigh the risks, taking into account the harm already being done due to global heating? How would the world decide whether to deploy solar radiation modification (SRM), or even whether to conduct research? Who would make these decisions and what would the guardrails be? These questions are terrifying to contemplate. But so is the prospect of temperature rise beyond 1.5 degrees. Not surprisingly, there are deep divisions among the scientific community. Some scientists - including high-profile climate scientist James Hansen - consider our current situation is so dire that there should be a rigorous, rapid scientific assessment of the feasibility and impacts of SRM approaches. There are other scientists who are resolutely opposed to SRM, and consider it a dangerous distraction from a focus on decarbonisation and greenhouse gas drawdown. In this episode, I talk to Janos Pasztor who for seven years worked with the Carnegie Climate Governance Initiative, which took neither a pro- or anti- approach to SRM, instead focusing on governance issues around solar radiation management. He also talks about a new report on SRM issued by the EU Commission's top scientific advisory body. Janos's previous roles include UN Assistant Secretary General for Climate Change and senior advisor on climate change to then UN Secretary-General Ban Ki-Moon, in the lead-up to the 2015 Paris climate COP that led to the Paris Agreement. He has also held senior executive roles with environment group WWF International, the UN Environment Programme (known as UNEP), and with the secretariat to the UN Framework Convention on Climate Change."
Solar Geoengineering and Climate Justice | Climate on the Edge | Solar Geoengineering and Climate Justice Climate on the Edge 1:11:31 |
"In this episode of Climate on the Edge, host Susan Su sits down with Andrew Parker, founder and CEO of the Degrees Initiative, and a global leader in the field of Solar Radiation Management (SRM). Degrees uniquely focuses on SRM research for and by the Global South, and has pioneered groundbreaking research grants and initiatives from South Africa to Thailand."
YOUTUBE VIDEOSReducing Mortality in a Future with Extreme Heat: Part II | SilverLining "During the 2024 American Geophysical Union Conference, SilverLining and NYU Grossman School of Medicine, held "Reducing Mortality in a Future with Extreme Heat," at the Kimpton Hotel Monaco in Washington, DC. This conversation, titled "Research on Climate Intervention," was the second panel of the event, focused on research, governance and equity considerations for global-scale interventions in climate. The panelists engaged on topics including a discussion of the research needed to evaluate solar radiation modification (SRM) interventions, the practical and urgent considerations for governance and global participation and what’s at stake for younger generations."
Webinar: Stratospheric Aerosol Injection: A Pathway to Cooling the Planet | Healthy Climate Initiative "In this webinar, Dr. MacMartin will:
• Explain the science behind SAI
• Discuss its potential benefits and risks
• Highlight the role of informed preparation for society’s climate response"
Meer: Reflecting Sunlight to Cool the Planet | Healthy Climate Initiative "Abstract: As global temperatures rise, millions worldwide struggle with a lack of affordable cooling solutions. MEER, an innovative NGO, has developed low-cost reflectors that harness the power of sunlight reflection to cool households, buildings, and potentially entire cities. This groundbreaking approach offers a scalable pathway to cooling the planet and addressing urgent climate challenges.
Join Dr. Ye Tao, Founder and Executive Director of MEER, as he presents the science behind MEER reflectors, shares insights from pioneering projects in India, and Sierra Leone, and outlines an inspiring vision for scaling these transformative solutions worldwide."
Marine Cloud Brightening to Cool the Planet | Healthy Climate Initiative "Abstract: As the planet faces accelerating climate impacts, Marine Cloud Brightening (MCB) emerges as a promising, cost-effective solution to rapidly cool the Earth. By reflecting more sunlight back into space, MCB has the potential to slow global temperature rise, refreeze polar ice, and mitigate devastating weather events such as hurricanes, typhoons, droughts, and floods.
Join Dr. Brian von Herzen, Executive Director of Climate Foundation and Vice Chairman of HCI, as he explains the science behind MCB, and the potential for cooling the planet, including its benefits and risks. Learn about a groundbreaking intervention that could reshape our response to the climate crisis. Don't miss this opportunity to engage with cutting-edge climate solutions"
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