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“It isn’t going to happen the way that 99 percent of these papers model.”

Published Nov 2, 2025 9:00 AM EST

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In an eleventh-hour attempt to slow down global warming, some scientists have been proposing — or even testing, at a small scale — whether releasing aerosolized particles into the atmosphere to dim the Sun could lower global temperatures, effectively mimicking the effects of volcanic eruptions.

It’s a controversial idea that has drawn plenty of criticism from the scientific community as well, with experts pointing out the substantial societal implications and effectiveness of turning down the Sun’s rays.

Researchers at the Columbia Climate School, for instance, say we haven’t even begun to explore the possible consequences of stratospheric aerosol injections (SAI) — and are making assumptions that could exacerbate the dangers of messing with the environment.

“Even when simulations of SAI in climate models are sophisticated, they’re necessarily going to be idealized,” said Columbia aerosol scientist Faye McNeill, author of a paper published in the journal Scientific Reports, in a recent statement, as spotted by ScienceAlert.

“Researchers model the perfect particles that are the perfect size,” she added. “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.”

“There are a range of things that might happen if you try to do this,” she added, “and we’re arguing that the range of possible outcomes is a lot wider than anybody has appreciated until now.”

In their paper, McNeill and her colleagues discussed the limitations of proposed SAI projects, pointing out the litany of ways aerosols can interact with ecosystems. For instance, releasing aerosols in polar regions could interrupt tropical monsoon systems. The jet stream could also be offset by offloading the particles in equatorial regions.

The most common form of SAI being proposed would use sulfates, emulating the chemicals released by volcanic eruptions. However, such an approach could pose other risks, from acid rain to soil pollution, the researchers argued.

Other researchers are searching for alternatives to sulfates, including diamond and calcium carbonate. Just last week, Politico reported that a geoengineering startup had raised $60 million to develop a new particle that could be used to reflect the Sun’s radiation back into space.

But even then, other limitations start to show.

“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,” said coauthor and Columbia University aerosol scientist Miranda Hack in the statement. “A lot of the materials that have been proposed are not particularly abundant.”

Scientists also have to contend with these particles’ tendency to clump together, which could greatly undercut their effectiveness.

In short, proponents of SAI still have a lot to prove before we can start dimming the Sun, a controversial alternative to attacking the root cause of global warming: reducing fossil fuel consumption and expediting clean energy development.

“It’s all about risk trade-offs when you look at solar geoengineering,” said coauthor and Columbia climate economist Gernot Wagner. “It isn’t going to happen the way that 99 percent of these papers model.”

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