Focusing on the gaps in the governance of solar radiation modification

Jesse ReynoldsGuest post by Jesse Reynolds and Arunabha Ghosh 

[The views of guest post authors are their own and do not necessarily reflect any official positions of the authors’ organisations or C2G. We encourage a constructive conversation involving multiple viewpoints and voices] 

This blog is based on a new report published by Carnegie Climate Governance Initiative (C2G) Solar Radiation Modification: Governance gaps and challenges which has summary versions available in English中文Français and Español.


Although the international order has been particularly tested this year, it has always been diffused, with numerous countries and other actors pursuing diverse objectives that are negotiated and resolved via multiple decision-making sites and processes. Nevertheless, the Sustainable Development Goals provide a widely-supported framework for organising guiding collective decision-making and action. However, human-caused climate change presents a major obstacle to fulfilling the goals. The recent reports of the Intergovernmental Panel on Climate Change (IPCC) make this stark situation even clearer.  

Countries have taken action to reduce greenhouse gas emissions, but this continues to be insufficient. In this context, solar radiation modification (SRM) is an additional approach proposed to help lessen and manage climate change risks, typically by reflecting a small portion of incoming sunlight. According to current evidence, it could rapidly and reversibly reduce climate change, albeit imperfectly so. One suggested technique–stratospheric aerosol injection–seems to be technically feasible and have relatively low direct costs. At the same time, SRM’s research, evaluation, and possible use present numerous risks and diverse governance dimensions, some of which are challenging. Existing governance instruments, institutions, and processes address some, although not all, of these. 

Put together, SRM presents a high-stakes risk-risk trade-off with significant uncertainties, yet there are important gaps in its governance (here meaning the full range of means for deciding, managing, implementing, monitoring, and adjudicating policies and actions). Indeed, C2G’s mission is to catalyse the creation of effective governance, which would presumably be attentive of such gaps. To this end, we authored a recent paper identifying the governance gaps associated with SRM. One can approach these issues from many angles. We chose to divide SRM’s governance dimensions and challenges into those that would arise at various stages of its research, development, and possible use.  

The first set of issues are already salient during SRM’s indoor research. Here, the foundational question is whether it should be researched at all. If SRM is indeed to be investigated, then governance may need to enable research by funding, setting priorities, and coordinating efforts. The quality and reliability of research outputs could be ensured. Governance processes could also help legitimise research by, for example, keeping it consistent with widely held norms and principles; communicating the results and engaging with the public, thought leaders, and decision-makers; and internationally cooperating and building research capacity. How to address two particularly widespread concerns is unclear. One is that early research and evaluation activities might unduly bias future decisions in favour of SRM’s further development and use. The other widespread concern—indeed, the most influential one—is that SRM’s research, development, and evaluation could lessen and decelerate emissions reduction.  

Second, some governance dimensions and challenges primarily concern outdoors SRM research. These activities have been somewhat controversial, and some observers argue that this line of inquiry should remain indoors. Relatedly, the demands for legitimacy seem more stringent in the case of outdoor SRM research. Field tests and experiments could pose physical and environmental risks, which governance could aim to reduce. 

Looking toward SRM’s potential use, the question of whether to ever use SRM, and how such a decision could be legitimately made, have received much attention. But before approaching this matter, early international consultations could yield norms and objectives to guide SRM decision-making. Preventing and controlling unwanted SRM deployment may be its greatest governance challenge. States, intergovernmental organisations, and other actors could anticipate potential SRM contrary to international consensus. And along these lines is the need to legitimately enable operational SRM if and when international consensus is sufficient 

Finally, SRM’s use, if it ever happens, would engender other governance dimensions and challenges. The ongoing SRM would need to be managed, including preventing its sudden and sustained termination. Claims of unfair impacts may need to be adjudicated, and governance coils aim to prevent the undue use of SRM for political ends. Governance could strive to equitably share costs and burdens. 

Not all these governance dimensions and challenges would be left unaddressed. Instead, some governance relevant to SRM exists, although it is limited. Non-state actors can provide some guidance, particularly of small-scale SRM research and in the absence of action by countries and intergovernmental organisations. Indeed, several collections of scholars and others have put forth nonbinding principles for SRM research and possible use, which notably have several commonalities. National governance is diverse, but generally provides basic regulation of environmental risks through impact assessment, pollution, endangered species protection, and more. Currently, there are no international legal instruments with binding obligations that are specific to SRM. Some international governance rules, processes, and norms are directly applicable, while other multilateral environmental agreements could be adapted to govern SRM.  

Nevertheless, many governance gaps exist around SRM. Perhaps the most relevant is the current absence of a comprehensive international governance framework. This includes key questions on how choices on any potential deployment would be made, by whom, and in which forum or intergovernmental process. Others are facilitating responsible research, guiding outdoor experiments and engaging with the global public, integrating SRM with other climate responses, balancing commercial interests and governance concerns, and resolving any international disputes.

Many governance gaps exist around SRM. Perhaps the most relevant is the current absence of a comprehensive international governance framework.

Our paper offers potential means by which decision-makers could address them so that any research, evaluation, and possible use of SRM could be better aligned with widely held principles and objectives, such as the Sustainable Development Goals. 

Conversations about SRM governance are needed sooner rather than later. Governance gaps will likely evolve in the context of a rapidly warming world in which the risks faced are both known and unknown. SRM is not yet available as a deployable technique and its research is still at an early stage. Although the high-stakes choices surrounding whether to implement SRM remain distant, near-term steps could be taken so that in the future, highly consequential decisions are more likely to be relatively legitimate, effective, and less conflictual. Given that multilateral diplomacy takes time to develop, if governance gaps are to be addressed in time, then conversations between policymakers should begin now, not later. 


Jesse Reynolds is Executive Secretary, Global Commission on Governing Risks from Climate Overshoot; and Senior Policy Officer, Paris Peace Forum. 

Arunabha Ghosh is Chief Executive Officer, Council on Energy, Environment and Water (CEEW). 

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