The prospect of solar geoengineering, which would entail reflecting a small fraction of incoming sunlight back to space to cool the planet, has been slowly but steadily rising on the climate policy agenda. Early research suggests that solar geoengineering could substantially reduce climate risks, but its development and potential use would be accompanied by an array of ecological and sociopolitical risks and governance challenges. Here we reflect on our participation in a solar geoengineering governance scenario exercise conducted at the 2019 International Summer School on Geoengineering Governance. In the scenario with which we engaged, a group of ‘middle powers’ intend to force the issue of solar geoengineering onto the international agenda after decades of deadlock and in the face of intensifying climate impacts. As participants in this exercise, we confronted a range of problems and issues we judged likely to arise. In this article, we discuss a number of these, including the manner in which political considerations are likely to influence the physical and technical aspects of deployment schemes, as well as ways in which emergency framing may undermine political legitimacy. These and other aspects of possible future deployment of solar geoengineering warrant additional targeted scenario analysis.

太阳能地球工程需要将一小部分入射阳光反射回太空以冷却地球，其前景一直在气候政策议程上缓慢但稳步上升。早期研究表明，太阳能地球工程可以大幅降低气候风险，但其开发和潜在用途将伴随着一系列生态和社会政治风险以及治理挑战。在这里，我们反思我们参与了在 2019 年国际地球工程治理暑期学校进行的太阳能地球工程治理情景演练。在我们参与的情景中，在数十年的僵局和日益加剧的气候影响之后，一群“中等强国”打算将太阳能地球工程问题强加到国际议程上。作为本次练习的参与者，我们遇到了一系列我们认为可能出现的问题。在本文中，我们讨论了其中的一些问题，包括政治考虑可能影响部署方案的物理和技术方面的方式，以及紧急情况框架可能破坏政治合法性的方式。未来可能部署太阳能地球工程的这些和其他方面需要额外的有针对性的情景分析。