For the price of a cheap coffee, you can help dim the sun — at least, that’s the pitch being offered by a California startup with a name that sounds more like a sci-fi novella than a climate intervention scheme: Make Sunsets.
In a move that blends entrepreneurial ambition with unsettling scientific boldness, founder Luke Iseman is selling “cooling credits” to fund a DIY approach to geoengineering.
The process? Drive a Winnebago into the California hills, launch weather balloons packed with sulfur dioxide — a substance best known for being belched into the sky during volcanic eruptions — and hope they burst high enough in the stratosphere to block a fraction of sunlight. His customers, numbering over a thousand, are placing faith in this climate intervention with the hopes of slightly nudging the global thermostat downward.
This is not theoretical. It’s already happening. Iseman claims his balloons have released more than 240 pounds of sulfur dioxide this year. Legally speaking, he’s operating in a gray zone. No country has officially authorized private solar geoengineering, but many have yet to write laws explicitly prohibiting it. In the vacuum of regulation, companies like Make Sunsets — and its more secretive competitor Stardust — are forging ahead.
Solar geoengineering, once the domain of speculative fiction and academic white papers, has rapidly crossed into commercial territory. Its premise is simple, if ethically fraught: reflect sunlight away from Earth to slow down or counteract global warming. It’s cheap compared to carbon capture or the total decarbonization of the world economy. But it’s also controversial, not just because of potential health or environmental risks, but because it opens the door for unilateral climate action.
The climate itself is global, but the authority to modify it is anything but. That’s where critics — and there are many — raise alarms. “I do not trust the private sector to make good decisions for people,” said Shuchi Talati, founder of a nonprofit dedicated to solar geoengineering governance. Others point to the tech world’s infamous “move fast and break things” ethos as precisely the wrong mindset for tinkering with planetary systems.
Enter Stardust, a far more well-funded entity (backed by $75 million in venture capital) aiming to introduce a safer alternative to sulfur dioxide. Their secret formula? A still-undisclosed, supposedly inhalable reflective particle they claim won’t harm the ozone or cause cancer. Scientists aren’t buying it. David Keith, one of the foremost researchers in geoengineering, called Stardust’s safety claims “total, unadulterated bulls—.”
Secrecy hasn’t helped. The company has yet to publish promised research or outline its code of conduct. It’s also been caught lobbying Congress behind the scenes without proper disclosures. Even if it waits for a government mandate before acting, as its founders insist, the opaque nature of its operations has left scientists and the public deeply uneasy.
The deeper concern, however, may not be the startups themselves — but the vacuum they’re stepping into. Geoengineering, for all its risks, is becoming increasingly attractive as climate impacts accelerate and traditional mitigation stalls. If democratic governments don’t take the lead on policy, testing, and ethical debate, private actors may rush in with solutions too powerful — and too irreversible — to ignore.
