Solar geoengineering research and development

Research into solar geoengineering, specifically stratospheric aerosol injection (SAI), has highlighted both technical risks and proposed frameworks for future development.

Initial studies published in Geophysical Research Letters identified potential aviation safety risks associated with injecting sulfur compounds into the stratosphere. The research suggests that such methods could increase sulfuric acid concentrations along passenger flight paths, particularly near polar regions, potentially exceeding safe limits within aircraft cabins.

Following these findings, the nonprofit Reflective released a research roadmap for SAI. The proposal suggests that a coordinated global effort could complete necessary studies in roughly 10 years at a cost of $370 million, whereas uncoordinated efforts could take 20 years and cost $1.4 billion. The roadmap includes controversial recommendations for outdoor experiments involving sulfur dioxide release. While Reflective CEO Dakota Gruener stated the mission is to provide data fast enough to matter, many scientists and governance experts have raised concerns regarding the lack of international frameworks and the implications of testing technology that could alter the entire planet.

In September 2026, Reflective updated its research plan, detailing a process that mimics the cooling effects of volcanic eruptions through particle release. The organization maintains that a coordinated effort could reach a decision on the safety and viability of SAI in approximately 10 years at a cost of 322 million euros. However, the United Nations Environment Programme noted in 2026 that current scientific knowledge does not yet support solar radiation modification as a viable solution, emphasizing that such measures do not address the root cause of warming: rising greenhouse gas concentrations. Uncertainties remain regarding regional rainfall patterns, atmospheric chemistry, and the ozone layer.