Solar geoengineering is an emerging topic in climate-change discussions. To support future decisions on the deployment of this technology, society requires better estimates of its environmental impacts and limitations. As solar geoengineering has never been deployed, conclusions about its climatic effects are primarily obtained through models and natural analogues. As such, our confidence in projections of solar geoengineering, the basis for that confidence and how our confidence can be improved is limited. In this Perspective, we review our current understanding of uncertainty and risk in solar geoengineering via stratospheric aerosols. Using a risk-register framework, we illustrate key uncertainties, such as sub-grid-scale mixing or effects of stratospheric heating, investigations of which should be prioritized to transition the field to a mission-driven research agenda. We conclude with recommendations for possible avenues of research, including targeted model intercomparisons and appropriately governed small-scale field experiments.

太阳能地球工程学是气候变化讨论中的新兴话题。为了支持有关此技术部署的未来决策，社会需要对其环境影响和局限性进行更好的估算。由于从未进行过太阳能地球工程，因此有关气候影响的结论主要是通过模型和自然类似物得出的。因此，我们对太阳能地球工程预测的信心，这种信心的基础以及如何提高我们的信心是有限的。在此观点中，我们回顾了当前对通过平流层气溶胶进行的太阳地球工程不确定性和风险的理解。使用风险登记框架，我们说明了关键的不确定性，例如亚电网规模的混合或平流层加热的影响，应优先进行调查研究，以将该领域转变为任务驱动型研究议程。最后，我们为可能的研究途径提供了建议，包括有针对性的模型比对和适当控制的小规模现场试验。