The San Francisco-based nonprofit Reflective has released a comprehensive research roadmap aimed at guiding scientific efforts regarding solar geoengineering. The document outlines a series of studies and outdoor experiments intended to provide the data necessary for informed decision-making on stratospheric aerosol injection (SAI), a process that mimics volcanic cooling by releasing reflective particles into the atmosphere.

According to the report, a coordinated decade-long research effort would cost approximately $370 million. If the work remains uncoordinated, the organization estimates the timeline could extend to 20 years with costs reaching nearly $1.4 billion. The roadmap proposes a phased approach, beginning with computer simulations and laboratory studies, followed by small-scale outdoor releases of sulfur dioxide, and eventually larger-scale testing. Each phase includes “stage gates” intended to halt progress if experiments reveal significant risks or fail to provide expected insights.

The proposal has sparked debate within the scientific and policy communities. Proponents, such as former ARIA CEO Ilan Gur and Imperial College London’s Sebastian Eastham, argue that moving beyond computer simulations is essential to reduce uncertainty regarding the technology's effectiveness. Reflective CEO Dakota Gruener emphasized that the organization does not advocate for deployment but seeks to provide the tools for responsible evaluation, noting that the proposed sulfur releases are small compared to daily global aviation emissions.

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Conversely, critics remain skeptical of the research path. Many academics, including those supporting an international non-use agreement, argue that technical research fails to address fundamental governance questions, such as who would control the technology and how to ensure equitable outcomes. Legal scholar Wil Burns expressed concern that even if the technology is proven effective, it could create “termination shock”—a sudden surge in warming if the process were stopped—and raises issues of intergenerational equity.

Reflective, which has raised over $20 million since its 2023 inception, intends to treat this roadmap as a living document, updating it based on feedback from the research community and stakeholders.

Source: MIT Technology Review