1. It introduces unknown climate risks. Geoengineering projects could alter Earth systems in unintended ways. · 2. It may be ineffective.
An example of natural geoengineering, volcanic eruptions emit sulfur dioxide, which can cause cooler temperatures. (US Geological Survey).
On the one hand, SG may provide a cooling effect to offset global warming, reducing the risk of adverse climate change effects. On the other
Geoengineering is fraught with risks, uncertainties, and dangers that threaten to delay real climate action and cause more harm than good.
Central to the promise of geoengineering is its ability to deliver extremely large emissions reductions and/or displace or avoid large degrees of climate change
Our paper, *Impact of solar geoengineering on temperature-attributable mortality*, is a first effort to provide a quantitative risk-risk comparison for any solar geoengineering method. David was part of prior collaboration with Gabe Vecchi which produced an important estimate of solar geoengineering’s potential to reduce regional climate hazards. * Many groups have called for risk-risk analysis of solar geoengineering including the National Academy, NASEM 2021, The Carnegie Climate Governance Initiative, C2G and the call-for-balanceletter with Peter Singer, James Hansen, and Bjorn Stevens, as signatories, see paper. * The air pollution mortality estimate by Eastham combines the direct impacts of injected aerosol that makes it to the surface with climate-mediate changes in the amount of surface ozone and particulate air pollution produced from given industrial emissions. While not comprehensive, these are important risk pathways: temperature-attributable mortality may account for more than half of the monetized harms of climate change, and air pollution and ozone loss are among the most salient impacts of stratospheric sulfate geoengineering.
They find the mortality benefits of injecting the sulfate aerosols outweigh the costs by a factor of ten. The study also shows that the benefits
Alan Robock Benefits and Risks of Stratospheric Solar Radiation Management for Climate Intervention (Geoengineering) The BRIDGE 60 Definition of Terms Ideas for removing carbon dioxide from the atmosphere or reflecting sunlight to cool Earth used to be called geoengineering or climate engineering, but the favored term nowadays (e.g., AGU 2018; NRC 2015) is climate intervention. Volcanic stratospheric clouds are produced by injections of SO2, so that might be the gas of choice, but some have suggested H2SO4 to reduce growth of aerosol particles (e.g., Pierce et al. Outdoor research, which involves injecting salt par ticles into marine clouds or various substances into the stratosphere, requires governance, including review of potential environmental impacts, monitoring of the experiments, and sanctions if the researchers break the rules (e.g., Shepherd et al. Future research is planned with scenarios that might involve credible deployments, such as balancing over shoot scenarios to keep global warming at less than 1.5– 2.0 K above preindustrial temperatures (e.g., Tilmes et al.