The stringency of the 1.5 degree goal under the Paris Agreement, coupled with the mismatch between that goal and domestic mitigation pledges, inevitably directs attention onto the potential future role of solar radiation management (SRM) technologies. Such technologies, however, remain controversial, and analysis of their environmental, social and ethical implications is at an early stage. In this context, this paper distils four key governance objectives and proposes three specific policy interventions for the near-term governance of SRM technologies. Specifically, we build from existing literature to argue that SRM governance must simultaneously: guard against the risks of uncontrolled SRM development; enable potentially valuable research; build legitimacy for research and any future policy through broad public engagement and ensure that SRM is only considered as one part of a broader mitigation agenda. We propose three interventions to work towards those objectives in the near term by: developing a transparency mechanism for research; creating a global forum for public engagement and including consideration of SRM in the global stocktake under the Paris Agreement. Finally, we argue that carrying out these interventions requires a shared or ‘polycentric’ SRM governance structure that can build on the site-specific capabilities and preferences of existing international institutions. Key policy insights

Two recently proposed solar radiation management (SRM) experiments in the United States have highlighted the need for governance mechanisms to guide SRM research. This paper draws on the literatures on legitimacy in global governance, responsible innovation, and experimental governance to argue that public engagement is a necessary (but not sufficient) condition for any legitimate SRM governance regime. We then build on the orchestration literature to argue that, in the absence of federal leadership, U.S. states, such as California, New York, and other existing leaders in climate governance more broadly have an important role to play in the near-term development of SRM research governance. Specifically, we propose that one or more U.S. states should establish a new interdisciplinary advisory commission to oversee and review the governance of SRM research in their states. Centrally, we propose that state-level advisory commissions on SRM research could help build legitimacy in SRM research decisions through the inclusion of, at minimum: meaningful public engagement early in the research design process; an iterative and reflexive mechanism for learning and improving both participatory governance mechanisms and broader SRM governance goals over time; as well as mechanisms for adaptation and diffusion of governance mechanisms across jurisdictions and scales.

Solar radiation management (SRM) technologies would reflect a small amount of incoming solar radiation back into space before the radiation can warm the planet. Although SRM may emerge as a useful component of a global response to climate change, there is also good reason for caution. In June 2017, the Academic Working Group on Climate Engineering Governance released a policy report, “Governing Solar Radiation Management”, which developed a set of objectives to govern SRM in the near-term future: (1) keep mitigation and adaptation first; (2) thoroughly and transparently evaluate risks, burdens, and benefits; (3) enable responsible knowledge creation; and (4) ensure robust governance before any consideration of deployment. To advance the governance objectives identified above, the working group developed twelve recommendations, grouped into three clusters: (1) create politically legitimate deliberative bodies; (2) leverage existing institutions; and (3) make research transparent and accountable. This communication discusses the rationale behind each cluster and elaborates on a subset of the recommendations from each cluster.

A prominent recent perspective article in this journal and accompanying open letter propose a broad international “non‐use agreement” (NUA) on activities related to solar geoengineering (SG). The NUA calls on governments to renounce large‐scale use of SG, and also to refuse to fund SG research, ban outdoor experiments, decline to grant IP rights, and reject discussions of SG in international organizations. We argue that such pre‐emptive rejection of public research and consultation would deprive future policy‐makers of knowledge and capability that would support informed decisions to safely and equitably limit climate risk, sustain human welfare, and protect threatened ecosystems. In contrast to the broad prohibitions of the NUA, we propose an alternative near‐term pathway with five elements: assess SG risks and benefits in the context of related climate risks and responses; distinguish the risks and governance needs of SG research and deployment; pursue research that treats uncertainties and divergent results even‐handedly; harness normalization of SG as a path to effective assessment and governance; and build a more globally inclusive conversation on SG and its governance. These principles would support a more informed, responsible, and inclusive approach to limiting climate risks, including judgments on the potential role or rejection of SG, than the prohibitory approach of the NUA.This article is categorized under: Climate and Development > Social Justice and the Politics of Development Policy and Governance > Multilevel and Transnational Climate Change Governance Policy and Governance > National Climate Change Policy

This article adds conceptual discipline to a well‐rehearsed but largely intuitive argument within the climate engineering community that carbon dioxide removal (CDR) and solar radiation management (SRM) should be treated separately – ‘split’ rather than ‘lumped’ – in policy discussions. Specifically, we build the first, theoretically derived argument for ‘splitting’. We do this by engaging a set of theoretical insights from the international relations literature, having to do with the relationship between problem structure and institutional design. Centrally, we apply some key elements of problem structure – which allows us to compare policy issues along variables such as geographic scope, costs, and actor number and asymmetries – to the cases of SRM and CDR. By analyzing their problem structures, we demonstrate that SRM and CDR are different in ways that are likely to yield different state preferences for institutional design, and thus policy proposals that split SRM and CDR are more likely to be adopted by states. In short, we construct a theoretical argument for ‘splitting’ SRM and CDR governance in global policy discussions.