Geoengineering: the last resort nobody wants to talk about

In late 2022, a former tech entrepreneur named Luke Iseman started launching weather balloons filled with sulfur dioxide from a truck in Mexico’s Baja California, on the theory that the particles would drift into the stratosphere and reflect a sliver of sunlight back into space. He sold “cooling credits” online for about $10 each. No peer review, no environmental impact study, no permission from the Mexican government - just a guy with balloons and a Stripe account, unilaterally running the first known open-air solar geoengineering deployment on Earth. Mexico found out from press coverage, not from Iseman, and moved within weeks to ban the practice outright. I bring this up first because I think it’s the single most important fact in this entire topic: the barrier to entry for altering the planet’s atmosphere on purpose is currently roughly the same as the barrier to entry for a weather balloon and a chemistry supply order.

That’s the part that makes “nobody wants to talk about it” not quite true anymore. Solar geoengineering - deliberately reflecting sunlight to cool the planet, most commonly discussed as stratospheric aerosol injection - has been the subject nobody in mainstream climate policy wanted to touch for exactly the reason you’d expect: even raising it as a serious option sounds like giving up on cutting emissions, or worse, like handing a permission slip to keep burning fossil fuel because there’s now a backup plan. But the backup plan is being built anyway, right now, mostly outside any government’s direct control, and pretending otherwise doesn’t slow it down. It just means the people doing it aren’t accountable to anyone.

Stardust Solutions is the more serious version of the same instinct, and in some ways it worries me more precisely because it’s more serious. Founded in 2023 by Yanai Yadov, a former deputy chief scientist at the Israeli Atomic Energy Commission, alongside Amiad Spektor and Eli Waxman, the company has raised $75 million total, including a $60 million round in October 2025 that’s the largest ever raised by a solar radiation management company. It’s pursuing aircraft-based aerosol deployment, has been notably tight-lipped about its actual methods and materials, and as of recent reporting had published no peer-reviewed research on its approach, despite claiming a peer-reviewed publication was coming in early 2026. A for-profit company, backed by venture capital that presumably wants a return, developing a technology whose entire value proposition is altering global climate patterns, without the normal scientific transparency that would let outside experts actually evaluate what it’s doing - that’s a genuinely uncomfortable combination, and it’s happening with real money behind it, not as a thought experiment.

Government involvement exists, but it’s thin and inconsistent in a way that tells its own story. The UK’s Advanced Research and Invention Agency has committed £57 million to a program called “Exploring Climate Cooling,” reportedly the first Western government funding for outdoor solar geoengineering experiments - a meaningful step toward bringing this research into public, accountable hands rather than leaving it to founders with balloons. Harvard’s own SCoPEx experiment, by contrast, spent years stuck in planning and community consultation before being shelved in 2024 without ever launching a single test flight, undone by exactly the public trust problems that a company like Stardust seems inclined to skip past entirely. And in the US, the response has been to ban rather than study: Florida passed SB 56 in 2025, criminalizing weather modification and geoengineering activity in state airspace, joining a handful of states moving to prohibit the practice outright rather than fund research into it. So within the same few years you get a serious, funded UK government research program, a US state making it a crime, a secretive Israeli-founded startup with $75 million, and a solo operator who got an entire country to change its law by launching balloons out of a truck. That’s not a coordinated global approach to a planetary-scale technology. That’s not really an approach at all.

The genuinely alarming part, to me, is the total absence of binding international governance sitting underneath all of this activity. There is no treaty that specifically covers stratospheric aerosol injection. The London Protocol touches ocean-based geoengineering like iron fertilization, and a 2019 push at the UN Environment Assembly to establish some kind of oversight framework failed to reach agreement at all. The EU’s own scientific advisors called for a moratorium on solar geoengineering deployment this year, precisely because they see the same gap I’m describing: real deployments already happening, real money flowing into the technology, and no enforceable global rule about who’s allowed to do it, at what scale, with what oversight, or who’s liable if something goes wrong at a scale that, by design, doesn’t respect national borders.

The core scientific worry isn’t really about whether the sunlight-reflecting part works - the physics of aerosols scattering solar radiation is well understood, going back to what’s observed after large volcanic eruptions. It’s about what happens afterward: modeling suggests stratospheric aerosol injection could meaningfully disrupt the Asian and African monsoon systems that hundreds of millions of people’s agriculture depends on, and it creates something researchers call termination shock - if a large-scale deployment ever had to stop suddenly, for funding, political, or technical reasons, the suppressed warming would come back extremely fast, faster than ecosystems or agriculture could adapt to. A single company’s funding running out, or a war disrupting a supply chain, becomes a climate event in its own right. That’s an enormous amount of irreversible planetary risk to have concentrated in the hands of whoever happens to be funding the aircraft that year.

I don’t think the honest position here is “ban all research,” and I don’t think it’s “let the market figure it out” either - both of those are the easy version of an argument that deserves a harder one. Given that this is already happening, unilaterally, with balloons and with venture capital, the actual choice in front of us isn’t whether solar geoengineering research proceeds. It’s whether it proceeds inside a framework with real transparency, real international oversight, and real accountability for what happens if it goes wrong - or whether it keeps proceeding the way it has so far, which is: whoever moves first and doesn’t ask permission gets to set the terms for everyone else on the planet.