Legitimacy and procedural justice: how might stratospheric aerosol injection function in the public interest?

This article investigates the feasibility of stratospheric aerosol injection (SAI) as a method of solar geoengineering to mitigate global heating. SAI, which mimics the cooling effect of volcanic eruptions, is a high-leverage approach with potential for rapid deployment. However, the numerous uncertainties associated with "hacking the planet" make it crucial to consider how SAI can be developed and implemented in a way that benefits humanity. The article examines SAI as an institution—including research, development, experimentation, and deployment—governed by norms, procedures, rules, and mechanisms. Given the urgency of the climate crisis and the inadequacy of current decarbonization efforts, SAI may become a necessary tool alongside mitigation and negative emissions technologies. While previous research has explored the normative desiderata of SAI, including effectiveness, efficiency, distributive justice, and political feasibility, this article focuses specifically on the critical role of legitimacy and procedural justice in ensuring its operation in the public interest. The authors emphasize the risk of SAI being captured by elites and manipulated to serve private interests; therefore, legitimacy and procedural justice are vital to avoid this and ensure the institution operates for the benefit of society as a whole. The public interest is defined as the yardstick to assess if public actions benefit society overall, prioritizing long-term social well-being and minimizing climate-related harm.

Existing literature examines the normative desiderata of SAI, focusing on effectiveness, efficiency, distributive justice, and political feasibility. While some works explore legitimacy, they employ varying perspectives and scopes. Few focus on procedural justice; a notable exception is Callies (2018, 2019a), but this work treats procedural justice as one among many criteria. The existing literature is divided on the establishment of new governance systems for solar geoengineering, with some advocating for leveraging existing structures and others proposing new systems. This article argues that legitimacy and procedural justice should be inherent to SAI itself, rather than imposed by external governance. Different perspectives on the definition of 'public interest' are also noted, with the paper adopting a view emphasizing long-term societal benefit and minimization of climate-related harm.

The article employs a normative analysis, drawing upon neo-institutional theory, evolutionary economics, and economic sociology. It distinguishes between criteria (long-term moral yardsticks) and standards (more concrete moral references that inform institutional functioning). Criteria are broad principles, while standards offer more practical indications and suggest governance options. The analysis focuses on two criteria of legitimacy (avoidance of serious injustice and provision of reliable information) and two criteria of procedural justice (impartiality and equality of opportunity). For each criterion, corresponding standards are developed, illustrating their implications and suggesting morally sound governance options. The concept of normative legitimacy, focusing on output legitimacy, emphasizes the institution's design and how its output serves the public interest. This contrasts with descriptive legitimacy, which relies on the acceptance of those involved. The article emphasizes the importance of prioritizing vulnerable populations and avoiding imposing disproportionate burdens upon them. Transparency is essential for maintaining public trust and preventing manipulation by elites. Procedural justice is addressed through impartiality (equal participation) and equality of opportunity (equal understanding of issues). The article specifically shapes and develops criteria and standards to maximize the likelihood that SAI functions in the public interest, given the high risk of capture by elites.

The article identifies four standards: Priority (for vulnerable populations), Transparency (ensuring access to reliable information and accountability), Involvement (impartial participation of all relevant agents), and Knowledge (equal opportunity for understanding SAI's functioning). The Priority standard proposes a social vulnerability-based approach to distribute benefits, mirroring the progressivity principle used in fiscal systems. The Transparency standard suggests establishing an independent consultative forum to monitor SAI's functioning and provide information to stakeholders. The Involvement standard advocates for a platform enabling impartial agent participation, monitoring, and revision of decision-making processes. The Knowledge standard emphasizes generating, integrating, and providing timely and fit-for-purpose knowledge to reduce complexity and inform decisions. The article highlights the necessity of continuously checking and recalibrating legitimacy and procedural justice in SAI due to the dynamic and evolving nature of the institution and its operating context. An independent consultative forum, external to any specific SAI initiative, is proposed as a mechanism for continuous operationalization and modification of standards. This forum should include diverse members (experts, practitioners, civil society representatives) to ensure inclusivity and effectiveness. The article concludes that incorporating and maintaining legitimacy and procedural justice in SAI would greatly increase its effectiveness and likelihood of operating in the public interest.

The findings address the research question by providing a framework for establishing and maintaining legitimacy and procedural justice in SAI. The significance lies in offering concrete criteria, standards, and governance options that enhance the likelihood of SAI serving the public interest. The framework's relevance stems from the urgency of climate change and the potential role of SAI in mitigation efforts, particularly in navigating the challenges of uncertainty, complexity, and the risk of capture by private interests. The proposed governance structures, such as the independent consultative forum, address concerns about accountability and transparency, fostering public trust and minimizing the risk of SAI being used for purposes other than the common good. The integration of social vulnerability principles into SAI design ensures fairness and prioritization of the most vulnerable populations.

This article provides a novel framework for ensuring the legitimacy and procedural justice of SAI, crucial for its effective functioning in the public interest. The proposed criteria, standards, and governance mechanisms address the complexity and uncertainties inherent in SAI. The iterative approach to checking, calibrating, and contextualizing standards ensures adaptability and long-term relevance. Future research could explore the practical implementation of these recommendations within different political and societal contexts, focusing on designing effective consultative forums and measuring the success of the proposed vulnerability-based benefit distribution models.

The article's normative approach inherently relies on subjective value judgments concerning the definition of 'public interest' and the prioritization of vulnerable populations. The practical implementation of the proposed governance structures might encounter challenges related to political feasibility and the coordination of diverse stakeholders. The effectiveness of the proposed framework depends on the commitment of relevant actors to uphold the principles of legitimacy and procedural justice. Further research is needed to assess the real-world applicability of the proposed framework and to address potential challenges in its implementation.