Frank Keutsch

Irvine, Peter, Elizabeth Burns, Ken Caldeira, Frank Keutsch, Dustin Tingley, and David Keith. “Expert judgments on solar geoengineering research priorities and challenges.” EarthArXiv (2021). Publisher's VersionAbstract
Solar geoengineering describes a set of proposals to deliberately alter the earth’s radiative balance to reduce climate risks. We elicit judgements on natural science research priorities for solar geoengineering through a survey and in-person discussion with 72 subject matter experts, including two thirds of all scientists with ≥10 publications on the topic. Experts prioritized Earth system response (33%) and impacts on society and ecosystems (27%) over the human and social dimensions (17%) and developing or improving solar geoengineering methods (15%), with most allocating no effort to weather control or counter-geoengineering. While almost all funding to date has focused on geophysical modeling and social sciences, our experts recommended substantial funding for observations (26%), perturbative field experiments (16%), laboratory research (11%) and engineering for deployment (11%). Of the specific proposals, stratospheric aerosols received the highest average priority (34%) then marine cloud brightening (17%) and cirrus cloud thinning (10%). The views of experts with ≥10 publications were generally consistent with experts with <10 publications, though when asked to choose the radiative forcing for their ideal climate scenario only 40% included solar geoengineering compared to 70% of experts with <10 publications. This suggests that those who have done more solar geoengineering research are less supportive of its use in climate policy. We summarize specific research recommendations and challenges that our experts identified, the most salient of which were fundamental uncertainties around key climate processes, novel challenges related to solar geoengineering as a design problem, and the challenges of public and policymaker engagement.

Frank Keutsch – laboratory studies of stratospheric aerosol: a critical gap for reducing uncertainties of radiative and chemical impact of geoengineering and non-geoengineering aerosol under UT/LS conditions

Solar radiation management (SRM) via stratospheric aerosol injection could in principle have a faster response than emissions cuts and even aggressive carbon capture in order to achieve the IPCC 1.5°C target, although fast changes would have significant associated risks. Some of the risks of SRM using sulfate aerosol, the aerosol until recently believed to be the only naturally occurring aerosol in the stratosphere, carries significant risks. Besides the risk of ozone loss, stratospheric heating is a leading risk, as it...

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Frank Keutsch — Stratospheric Controlled Perturbation Experiment (SCoPEx)

SCoPEx is a scientific experiment to advance understanding of stratospheric aerosols that could be relevant to solar geoengineering. It aims to reduce the uncertainty around specific science questions by making quantitative measurements of some of the aerosol microphysics and atmospheric chemistry required for estimating the risks and benefits of solar geoengineering in large atmospheric models. SCoPEx will address questions about how particles interact with one another, with the background stratospheric air, and with solar and infrared radiation. Improved understanding of these...

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