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Geoengineering startup’s claim it got ‘OKs to launch’ from the FAA doesn’t stand up to scrutiny

Geoengineering startup’s claim it got ‘OKs to launch’ from the FAA doesn’t stand up to scrutiny


A couple dudes want to cool the planet by releasing balloons filled with sulfur dioxide. They say they got ‘OKs to launch’ from officials; officials say otherwise.

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Bright orange sunshine pokes through dark clouds in the sky at sunset.
Photo by George Rose / Getty Images

Controversial solar geoengineering startup Make Sunsets says it released three balloons carrying atmosphere-altering particles in Reno, Nevada, this month. It’s an escalation of the company’s questionable climate change-fighting tactics, which got it banned from launching balloons in Mexico in January. And while the company says it got the green light from the FAA and local authorities, officials say no such authorization was granted.

The way Make Sunsets explains it, this kind of geoengineering is a solution to humanity’s epic failure to stop planet-heating pollution. But experts say Make Sunsets has jumped the gun with its experiments — even those who are optimistic about solar geoengineering. There are still way too many questions over whether the tactic might help or cause more harm to our planet. Nevertheless, the company is making claims about its work that it hasn’t been able to back up. 

The company is making claims about its work that it hasn’t been able to back up

Make Sunsets is attempting to replicate the way volcanic eruptions have temporarily cooled the planet in the past. Volcanoes often spew sulfur dioxide, which combines with water in the stratosphere to create a hazy layer of sulfuric acid droplets that can reflect solar radiation. Mimicking this process artificially, called stratospheric aerosol injection (SAI) or solar geoengineering, has been a hot topic for years. The two-person team at Make Sunsets is just the first company to throw caution to the wind and go for it regardless of the potential consequences. 

The irreverence with which Make Sunsets tackles such a loaded topic is easy to see from its website. “We’ll happily debate anyone on this, just confirm an audience of at least 200 people and we’ll find the time to try and convince you,” the FAQ page says with a winking emoji in a section underneath the subtitle “I would like you to stop doing this.” The company blog post attempting to explain what SAI is was mostly written using ChatGPT. Make Sunsets co-founder Andrew Song tells Time he got a potential new sales slogan, “sunscreen for the Earth,” by similarly querying the chatbot to explain geoengineering to a five-year-old.

The startup’s rough-and-tumble experiments are even more telling. Song and co-founder Luke Iseman lit up fungicide on a grill to create the sulfur dioxide gas in a cringey scene Time describes as a “sulfur barbecue” in a Reno parking lot with families passing by cluelessly. Make Sunsets then funnels the gas into three weather balloons to unleash the small amount of sulfur dioxide on the stratosphere. 

Two guys stand in a parking lot with a small blue charcoal grill between them.
Make Sunsets co-founders Luke Iseman and Andrew Song in a parking lot where they’ll light up sulfur-based fungicide for their experiment.
Screenshot by The Verge of a video Make Sunsets uploaded to YouTube.

Make Sunsets did the same with two balloons in Mexico last year. At the time, they lacked tracking devices capable of checking whether the balloons even got high enough to deliver the sulfur particles to the stratosphere. The company also failed to consult with local authorities. In January, Mexico’s Secretariat of Environment and Natural Resources said it would bar future experiments to protect nearby communities and prevent any unintended environmental fallout.

This time, in Reno, Make Sunsets proudly says in a blog post that it received “OKs to launch” from the Federal Aviation Administration and Reno International Airport prior to the experiment — claims The Verge was unable to verify. 

“In spite of being the most huggable objects in the sky, many people have been nervous about balloons lately. Fortunately, aviation officials kept clear heads and were examples of government working to facilitate safe, small-scale, innovative experimentation,” Make Sunsets says in the blog.

Officials might have kept clear heads, but they don’t seem to have given Make Sunsets any official “OK.” Public affairs coordinator for the Reno-Tahoe Airport Authority Nicolle Staten said in an email that the agency “did not give any permissions or approvals … We are not certain on our authority to give approval on something like this, however if asked, our answer would be no.” The Airport Authority says it received a call from Make Sunsets and referred the company to the FAA. In an email to The Verge, the FAA says it doesn’t need to approve an unmanned free balloon flight unless it requires a waiver from regulations. 

When asked about the discrepancy between Make Sunsets’ blog post and the Reno-Tahoe Airport Authority’s response, Iseman points to an FAA NOTAM alert issued to notify pilots of potential flight hazards. “Perhaps the discrepancy is that they just confirmed receipt of the NOTAM and did not issue any kind of official approval, as there was none to be issued?” Iseman writes in the email.

The FAA also notes in an email that it “is an aviation safety agency and our regulations pertain to aviation safety.” In other words, it’s not in charge of monitoring any attempted geoengineering. Policy just hasn’t caught up with that kind of atmospheric tampering. While there’s a quasi-de facto moratorium on large-scale geoengineering from a 2010 United Nations biodiversity conference, it’s vague and excludes small-scale scientific research.

What Make Sunsets is attempting, however, is far from scientific, experts tell The Verge. “I don’t even know what to call it,” Paul Newman, Chief Scientist for Earth Sciences at NASA’s Goddard Space Flight Center, told The Verge in a January interview. “Science is about numbers. If you got no numbers, there’s no science. So even as a technology demonstration, it was nothing.” 

“Science is about numbers. If you got no numbers, there’s no science.”

Unlike its experiment in Mexico, Make Sunsets did attach tracking devices to two of the balloons it launched in Reno. But that still didn’t work too well. They were able to track the flight path but didn’t get consistent readings on altitude. Because of that, Make Sunsets was unable to make good on the purported climate service it’s already trying to sell to consumers. The company sells “cooling credits” at $10 per gram of sulfur dioxide. The credit is supposed to represent the cooling effect that sulfur dioxide might have in the stratosphere. But it doesn’t work if the sulfur dioxide never gets that far. 

Since Make Sunsets couldn’t confirm whether its two tracked balloons reached an altitude greater than 20km, it decided not to count them towards fulfilling cooling credit orders. But the company was haphazard with that decision, too. “A friend who is also a customer” released the third balloon in Reno without any tracking device at all, according to Make Sunsets’ blog. Per the friend / customer’s wishes, that balloon counted despite lacking any concrete data on its success. “They decided to count this as fulfilling their order of 1 Cooling Credit: first paid deployment done!” the blog says.

For now, Make Sunsets’ experiments are so minuscule anyway that they’re unlikely to have any kind of meaningful impact, good or bad. Each balloon carries less than 10 grams of sulfur dioxide. The US emitted about 1.8 million tons of sulfur dioxide in 2021 alone, mostly from burning fossil fuels. That figure has fallen over the decades, thanks to policies under the Clean Air Act. As a pollutant, sulfur dioxide can cause acid rain and breathing it in can have harmful effects on the lungs. 

A man stands in the middle of a grassy field carrying a large white weather balloon.
Make Sunsets CEO Luke Iseman stands with a balloon just before releasing it.
Screenshot by The Verge of a video Make Sunsets uploaded to YouTube.

Scientists are also studying the impact SAI might have on Earth’s ozone layer as it changes the chemistry of the stratosphere. “We’re confident that you would probably make the Antarctic ozone hole worse, and significantly worse if you began to do [stratospheric] aerosol injections,” Newman tells The Verge

Even so, with climate change quickly escalating, some research groups and even the Biden administration are cautiously assessing solar geoengineering as a way to cool the planet. But even some of the most ardent advocates for solar geoengineering research are pissed about Make Sunsets’ haphazard foray into it.

“This isn’t like a technical problem that we didn’t know how to put sulfur in the stratosphere that needs to be solved by some bright entrepreneurs,” says David Keith, a professor at Harvard University and faculty director of the school’s solar geoengineering research program. “The challenge is understanding what the risks are, predicting the side effects, figuring out the most effective ways to use these technologies in a way that would give the maximum human benefit with a minimum risk.” 

The other major challenge, he says, is making collective decisions on how to deploy this kind of planet-altering technology. That’s just the opposite of a couple guys grilling sulfur in a parking lot, letting their balloons fly, and trying to turn a profit from it.