Scientists Warn Solar Geoengineering Faces Major Practical Hurdles Beyond Climate Models

The Reality Gap in Solar Geoengineering

Solar radiation management, once considered a fringe concept, is now gaining serious scientific attention as a potential climate intervention strategy. However, according to reports from Columbia University researchers, the practical challenges of implementing stratospheric aerosol injection (SAI) are being dramatically underestimated. While hundreds of studies have modeled how SAI might work to offset global warming, sources indicate there’s a significant gap between idealized simulations and real-world implementation.

The Reality Gap in Solar Geoengineering
Deployment Complexities and Climate Impacts
Material Limitations and Supply Chain Challenges
Technical Challenges and Performance Concerns
Governance and Implementation Realities

Deployment Complexities and Climate Impacts

Analysts suggest that even sophisticated climate models present idealized scenarios that don’t account for practical limitations. “When simulations of SAI in climate models are sophisticated, they’re necessarily going to be idealized,” says V. Faye McNeill, an atmospheric chemist and aerosol scientist at Columbia’s Climate School and Columbia Engineering. “Researchers model the perfect particles that are the perfect size. And in the simulation, they put exactly how much of them they want, where they want them. But when you start to consider where we actually are, compared to that idealized situation, it reveals a lot of the uncertainty in those predictions.”

The report states that latitude appears to be the most significant variable in deployment strategy. SAI concentrated in polar regions would likely disrupt tropical monsoon systems, while equatorial releases could affect the jet stream and atmospheric circulation patterns. “It isn’t just a matter of getting five teragrams of sulfur into the atmosphere,” McNeill emphasizes. “It matters where and when you do it.”

Material Limitations and Supply Chain Challenges

Beyond deployment strategies, researchers have identified serious material constraints that could undermine SAI efforts. While volcanic eruptions like Mount Pinatubo in 1991 have demonstrated the cooling potential of stratospheric aerosols, they also caused unintended consequences including monsoon disruption and ozone depletion. The use of sulfates for SAI could pose similar risks, leading scientists to explore alternative mineral aerosols., according to industry experts

According to the analysis, proposed alternatives include calcium carbonate, alpha alumina, rutile and anatase titania, cubic zirconia, and even diamond. However, sources indicate that material availability presents a major obstacle. “Scientists have discussed the use of aerosol candidates with little consideration of how practical limitations might limit your ability to actually inject massive amounts of them yearly,” says Miranda Hack, the paper’s lead author and an aerosol scientist at Columbia University.

The research suggests that diamond, while optically suitable, is insufficiently abundant. Cubic zirconia and rutile titania might theoretically meet demand, but economic modeling indicates increased demand would strain supply chains and dramatically increase costs. Only alpha alumina and calcium carbonate appear to exist in sufficient quantities without driving prices to prohibitive levels.

Technical Challenges and Performance Concerns

Even with available materials, analysts suggest significant technical hurdles remain. At the sub-micron particle size required for effective SAI, mineral alternatives tend to clump into larger aggregates that are less effective at reducing sunlight. “Instead of having these perfect optical properties, you have something much worse,” Hack explains. “In comparison to sulfate, I don’t think we would necessarily see the types of climate benefits that have been discussed.”

These practical considerations—spanning deployment strategies, governance, material availability, and physical properties—make SAI even more uncertain than previously acknowledged, according to the researchers. The study, coauthored by Daniel Steingart of the Columbia Electrochemical Energy Center, emphasizes that these limitations should be fully considered when evaluating solar geoengineering as a climate solution.

Governance and Implementation Realities

Given the complex variabilities in SAI deployment, researchers suggest that effective implementation would require centralized, coordinated efforts. However, geopolitical realities make such coordination unlikely. Climate economist Gernot Wagner from Columbia Business School, who collaborated on the research, notes that “it’s all about risk trade-offs when you look at solar geoengineering.”

Wagner adds that given the messy realities of SAI implementation, “it isn’t going to happen the way that 99% of these papers model.” The researchers conclude that while solar radiation management continues to gain traction as a climate intervention, the practical challenges extend far beyond what current simulations capture, requiring more comprehensive consideration of real-world limitations.