In the face of increasingly clear climate-change impacts and continued inadequacy of efforts to reduce greenhouse-gas emissions and adapt to ongoing climate changes, increasing attention has been directed to geoengineering: deliberate large-scale interventions in the Earth’s climate system to moderate global warming. Such interventions could reduce risks in novel ways, but are controversial because they present an uncertain, high-stakes mix of potential benefits and risks. Solar geoengineering poses especially acute international governance needs, particularly in the case of potential future demands to use it. Many aspects of geoengineering present deep, ill-structured uncertainties that carry high stakes for near-term decisions, and are thus suitable for exploration through scenarios. This collection of papers reports on a major scenario exercise examining governance challenges and potential responses for solar geoengineering, held at the International Summer School on Geoengineering Governance in Banff, Canada in 2019. This opening paper introduces geoengineering and the concerns it raises, particularly as they pertain to governance; reviews the design and use of scenario exercises to inform decisions under uncertainty, including their prior uses related to climate change and geoengineering; and outlines the aims, design, and process of this scenario exercise.

面对日益明显的气候变化影响以及减少温室气体排放和适应持续气候变化的努力持续不足，地球工程越来越受到关注：有意对地球气候系统进行大规模干预以减缓全球变暖. 此类干预措施可以以新颖的方式降低风险，但存在争议，因为它们呈现出潜在收益和风险的不确定性、高风险组合。太阳能地球工程提出了特别迫切的国际治理需求，特别是在未来可能需要使用它的情况下。地球工程的许多方面都存在深刻的、结构不良的不确定性，这些不确定性对近期决策具有很高的风险，因此适合通过情景进行探索。这本论文集报告了 2019 年在加拿大班夫地球工程治理国际暑期学校举办的一项重大情景演练，该演练检查了太阳能地球工程的治理挑战和潜在响应。这篇开场论文介绍了地球工程及其引起的关注，特别是当它们与治理有关；审查情景演练的设计和使用，以在不确定的情况下为决策提供信息，包括其先前与气候变化和地球工程相关的用途；并概述了此情景演练的目标、设计和过程。特别是因为它们与治理有关；审查情景演练的设计和使用，以在不确定的情况下为决策提供信息，包括其先前与气候变化和地球工程相关的用途；并概述了此情景演练的目标、设计和过程。特别是因为它们与治理有关；审查情景演练的设计和使用，以在不确定的情况下为决策提供信息，包括其先前与气候变化和地球工程相关的用途；并概述了此情景演练的目标、设计和过程。