A new report from the nonprofit Reflective outlines the experiments needed to better understand solar geoengineering, a concept that involves releasing reflective particles into the stratosphere to counteract climate change. Reflective estimates that if all the work is done in a coordinated way, it would take about a decade and cost around $370 million. However, some argue that the first-order questions are not technical but about who would control such a powerful technology.

The report highlights the path to addressing uncertainties, from additional computer simulation studies and lab experiments to outdoor experiments releasing sulfur dioxide into the stratosphere. The initial phase, expected to last two to three years, is projected to cost between $30 and $75 million. The full research stage could cost between $70 and $150 million over four to eight years.

Reflective, a research organization that funds studies on solar geoengineering, has incorporated in late 2023 and has quickly become an important player in the field. It has raised over $20 million from prominent charities and individuals, and it has provided around $4 million to several dozen research groups. Reflective has also undertaken projects such as the development of an open-source solar geoengineering simulator and an online hub for collaborative research.

Despite the potential benefits, the report acknowledges the controversy. Academics have signed an open letter calling for a ban on outdoor experiments, arguing that such a powerful technology could never be governed in a globally equitable way. The core question, according to some, is not about the technology itself but about who would control and deploy it, and for whose benefit. The world may need to make very consequential decisions on timelines far shorter than our research system is prepared for.