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The widespread concern that research into and potential implementation of climate engineering would reduce mitigation and adaptation is critically examined. First, empirical evidence of such moral hazard or risk compensation in general is inconclusive, and the empirical evidence to date in the case of climate engineering indicates that the reverse may occur. Second, basic economics of substitutes shows that reducing mitigation in response to climate engineering implementation could provide net benefits to humans and the environment, and that climate engineering might theoretically increase mitigation through strong income effects. Third, existing policies strive to promote other technologies and measures, including climate adaptation, which induce analogous risk-compensating behaviours. If the goal of climate policy is to minimize climate risks, this concern should not be grounds for restricting or prohibiting climate engineering research. Three potential means for this concern to manifest in genuinely deleterious ways, as well as policy options to reduce these effects, are identified.

In the last decade, solar geoengineering (solar radiation management, or SRM) has received increasing consideration as a potential means to reduce risks of anthropogenic climate change. Some ideas regarding SRM that have been proposed have receded after being appropriately scrutinized, while others have strengthened through testing and critique. This process has improved the understanding of SRM's potential and limitations. However, several claims are frequently made in the academic and popular SRM discourses and, despite evidence to the contrary, pose the risk of hardening into accepted facts. Here, in order to foster a more productive and honest debate, we identify, describe, and refute five of the most problematic claims that are unsupported by existing evidence, unlikely to occur, or greatly exaggerated. These are: (A) once started, SRM cannot be stopped; (B) SRM is a right-wing project; (C) SRM would cost only a few billion dollars per year; (D) modeling studies indicate that SRM would disrupt monsoon precipitation; and (E) there is an international prohibition on outdoors research. SRM is a controversial proposed set of technologies that could prove to be very helpful or very harmful, and it warrants vigorous and informed public debate. By highlighting and debunking some persistent but unsupported claims, this paper hopes to bring rigor to such discussions.

Although solar geoengineering (alternatively ‘solar radiation management’ or ‘solar radiation modification’) appears to offer a potentially effective, inexpensive and technologically feasible additional response to climate change, it would pose serious physical risks and social challenges. Governance of its research, development and deployment is thus salient. This article reviews proposals for governing solar geoengineering. Its research may warrant dedicated governance to facilitate effectiveness and to reduce direct and socially mediated risks. Because states are not substantially engaging with solar geoengineering, non-state actors can play important governance roles. Although the concern that solar geoengineering would harmfully lessen abatement of greenhouse gas emissions is widespread, what can be done to reduce such displacement remains unclear. A moratorium on outdoor activities that would surpass certain scales is often endorsed, but an effective one would require resolving some critical, difficult details. In the long term, how to legitimately make decisions regarding whether, when and how solar geoengineering would be used is central, and suggestions how to do so diverge. Most proposals to govern commercial actors, who could provide goods and services for solar geoengineering, focus on intellectual property policy. Compensation for possible harm from outdoor activities could be through liability or a compensation fund. The review closes with suggested lines of future inquiry.

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