By Lara Williams / Bloomberg Opinion
Solar geoengineering, a bunch of techniques that aim to mask some effects of climate change by blocking sunlight, isn’t on the agenda for this month’s COP30, the U.N. climate conference. It ought to be. A record-breaking funding round for companies doing this stuff shows people are getting serious about trying to artificially cool the planet. That’s terrifying, especially when these businesses are largely unregulated.
In a recent poll of climate researchers, two-thirds said they thought there’d be an attempt to deploy large-scale solar radiation modification (SRM) by 2100. Only 9 percent said there wouldn’t be. That’s a worrying reflection of woeful progress on cutting emissions, and pessimism about the future. After all, solar geoengineering can only act as painkiller, not cure, for the climate crisis. And it comes with a range of poorly understood potential side effects.
What’s even more bone-chilling about the New Scientist poll is that more than half of researchers reckon deployment will be driven by a “rogue actor” such as a private company, billionaire or nation state going it alone.
Although the idea was once on the scientific fringes, it’s gaining traction among tech bros. Elon Musk recently posted on X that “a large solar-powered AI satellite constellation would be able to prevent global warming by making tiny adjustments in how much solar energy reached Earth.” I guess he means his own enormous fleet of Starlink satellites.
Millions have been spent on academic research into methods like stratospheric aerosol injection (SAI), in which a reflective material such as sulfur dioxide is sprayed into the stratosphere, and space mirrors, which are exactly what they sound like. Led by the United Kingdom’s Advanced Research and Invention Agency’s £56.8 million ($75 million) investment, this research can make a positive contribution as long as it’s transparent and not tied to a guarantee of eventual deployment.
But a surge of cash is heading toward profit-seeking ventures. Between 2007 and 2024, just $17.6 million in funding went to commercial solar geoengineers, according to non-profit SRM360, a fraction of the sector’s $185.7 million total funding. This year a single U.S.-Israeli start-up, Stardust, has raised $60 million from investors, PitchBook data shows. The funding was led by tech billionaire Chris Sacca’s venture firm Lowercarbon Capital and joined by others including Italy’s wealthy Agnelli family and Matt Cohler, an ex-Facebook executive.
Stardust is pursuing SAI, and wants to use a better particle than sulfates, which come with serious downsides. They cause acid rain, bring on asthma attacks and could damage the ozone layer, as a Royal Society briefing points out.
The perfect particle would be completely safe, robust, non-reactive and trackable. Does such a miracle item exist? Stardust is seeking a patent for something it believes fits the bill. But scientists are skeptical. Claims of an inert stratospheric particle are “nonsense,” according to an piece published this month by David Keith, professor of geophysical sciences at the University of Chicago, and Daniele Visioni, head of data for Reflective, a nonprofit that supports solar geoengineering research. Even diamonds, famously non-reactive, would alter chemistry 50 kilometers (31 miles) above our heads.
Transparency is vital with geoengineering, to cultivate public trust and make sure we’re not ignoring risks. Yanai Yedvab, Stardust’s co-founder and chief executive officer, told me he’s “fully committed” to this. Academic research on its technology will be published early next year in peer-reviewed journals, he says. To those who doubt that a safe, inert particle could exist, Yedvab invited them to look at the evidence before making up their minds.
Stardust isn’t the first business to chase commercialization of solar geoengineering. It arguably has a better approach than Make Sunsets, a two-person SAI startup that started releasing sulfur-filled weather balloons to generate “Cooling Credits” to sell, drawing the ire of the U.S. Environmental Protection Agency. One of the Make Sunsets duo, Luke Iseman, wrote to me that, “Neither of us is a climate scientist, so we don’t do original research or make unsupported claims.” He pointed to a web page that explained the math, with citations.
Yedvab assures me that governments will decide whether, when and how to deploy Stardust’s technology. The company has published some guiding principles, including a commitment to disclose “unfavorable results as well as favorable ones” and declining cooperation from anyone likely to engage in reckless deployment. This is laudable, but commercialized solar geoengineering still makes me very uneasy.
Companies exist to sell their products at a profit, which always creates incentives to downplay risks and talk up benefits. That’s a far worse problem when your technology comes with impacts that aren’t easily reversible or evenly distributed. The Royal Society notes that SRM may ameliorate many bad impacts of climate change, but not all of them, including drought and ocean acidification. If deployed without proper diligence, solar geoengineering might even worsen regional climate change, raising the risk of conflict.
And once humanity starts solar-radiation modification, it’ll be hard to stop. SRM merely masks the impact of greenhouse gas concentrations, in the absence of being able to do it via decarbonization. If it’s then halted or reined in, we’d experience termination shock, a rapid warming over the course of a decade or so. That could push our ability to adapt to climate change beyond its limits.
To work, the technology would also need to remain absolutely stable for potentially hundreds of years. Can any private company promise that in the face of economic downturns, wars, pandemics, sanctions and any other shocks that may come our way? In a free market, businesses don’t tend to survive forever. The average lifespan of a U.S. S&P 500 company is 15 years, down from 67 eight decades ago. That’s proof of a ferociously innovative country. It’s also a blink of an eye when you’re messing with nature.
In fairness, many great technologies have come out of a nexus of private company and academia, as Yedvab pointed out. Genome sequencing, space exploration and medical breakthroughs are all examples. The corporate world is better at incentivizing talent and building multi-disciplinary teams.
But a lack of the type of rigorous regulation you get in space or medical research is alarming. Some U.S. states have banned solar geoengineering based on chemtrail conspiracies. Mexico has barred experiments after Make Sunsets’ activities. The UN Convention on Biological Diversity puts a moratorium on geoengineering, but the U.S. hasn’t ratified the treaty. And it’s not legally binding.
The European Union issued a scientific opinion in December saying global governance is needed, but “no such framework exists, and it’s not clear how one could be created.” Hardly reassuring.
And while Stardust’s putting in the effort to legitimize its work, not everyone will do the same unless forced. Just as it isn’t the first solar geoengineering company, it won’t be the last. Governments need to act now.
Lara Williams is a Bloomberg Opinion columnist covering climate change.
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