Startup Claims It's Sending Sulfur Into the Atmosphere to Fight Climate Change

Make Sunsets sells "cooling credits" for $10 and alleges that 1 gram of sulfur particles offsets the impacts of 1 ton of carbon emissions.

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Stock photo of weather balloon in clouds
Make Sunsets claims it released weather balloons full of sulfur particles into the atmosphere. It’s part of a divisive, potentially dangerous, and unproven strategy for combatting climate change.
Photo: Tobias Lohf (Shutterstock)

A startup says it has begun releasing sulfur particles into Earth’s atmosphere, in a controversial attempt to combat climate change by deflecting sunlight. Make Sunsets, a company that sells carbon offset “cooling credits” for $10 each, is banking on solar geoengineering to cool down the planet and fill its coffers. The startup claims it has already released two test balloons, each filled with about 10 grams of sulfur particles and intended for the stratosphere, according to the company’s website and first reported on by MIT Technology Review.

The concept of solar geoengineering is simple: Add reflective particles to the upper atmosphere to reduce the amount of sunlight that penetrates from space, thereby cooling Earth. It’s an idea inspired by the atmospheric side effects of major volcanic eruptions, which have led to drastic, temporary climate shifts multiple times throughout history, including the notorious “year without a summer” of 1816.

Yet effective and safe implementation of the idea is much less simple. Scientists and engineers have been studying solar geoengineering as a potential climate change remedy for more than 50 years. But almost nobody has actually enacted real-world experiments because of the associated risks, like rapid changes in our planet’s precipitation patterns, damage to the ozone layer, and significant geopolitical ramifications.


Make Sunsets did not respond to an emailed request for comment on this story.

Though we know that sulfur particles can reflect sunlight away from Earth and cool the planet, the unintended consequences of such an action are less understood and potentially catastrophic. Some studies suggest that sulfur injection over the northern hemisphere would lead to massive droughts in the Sahel, Amazon rainforest, and elsewhere. Conversely, adding sulfur over the southern hemisphere could dramatically increase the number of Atlantic hurricanes in the northern hemisphere.


Plus, if and when we get enough sulfur into the atmosphere to meaningfully cool Earth, we’d have to keep adding new particles indefinitely to avoid entering an era of climate change about four to six times worse than what we’re currently experiencing, according to one 2018 study. Sulfur aerosols don’t stick around very long. Their lifespan in the stratosphere is somewhere between a few days and a couple years, depending on particle size and other factors.

Presumably, while this theoretical geoengineering is happening, we’d still be adding greenhouse gases into the atmosphere as well as sulfur particles. If, at any point, the sulfur delivery system were to break down, all that CO2 and methane would rapidly catch up with us—heating up the planet super quickly, all at once. Ecosystems would be thrown extra out of whack, as animals and plants would’ve stayed in place under the artificially cooled climate. Ocean acidification would continue unabated. TLDR; it would be a clusterfuck.


Now, Make Sunsets founder, Luke Iseman, is apparently walking all of us Earthlings toward the edge of that proverbial plank without any sort of regulatory approval or international permission.

Rogue agents independently deciding to impose geoengineering on the rest of us has been a concern for as long as the thought of intentionally manipulating the atmosphere has been around. The Pentagon even has dedicated research teams working on methods to detect and combat such clandestine attempts. But effectively defending against solar geoengineering is much more difficult than just doing it.

In Iseman’s rudimentary first trials, he says he released two weather balloons full of helium and sulfur aerosols somewhere in Baja California, Mexico. The founder told MIT Technology Review that the balloons rose toward the sky but, beyond that, he doesn’t know what happened to them, as the balloons lacked tracking equipment. Maybe they made it to the stratosphere and released their payload, maybe they didn’t. The weather balloon method has been previously proposed but not tested or demonstrated to be effective, according to an earlier 2019 MIT Technology Review report. Regardless, some scientists are alarmed by the attempt.


“To go ahead with implementation at this stage is a very bad idea,” Janos Pasztor, head of the Carnegie Climate Governance Initiative and a trained nuclear engineer, told MIT Technology Review. “The current state of science is not good enough,” to justify such experiments or predict their outcome, he explained.

Iseman and Make Sunsets claim that a single gram of sulfur aerosols counteracts the warming effects of one ton of CO2. But there is no clear scientific basis for such an assertion, geoengineering researcher Shuchi Talati told the outlet. And so the $10 “cooling credits” the company is hawking are likely bunk (along with most carbon credit/offset schemes.)


Even if the balloons made it to the stratosphere, the small amount of sulfur released wouldn’t be enough to trigger significant environmental effects, said David Keith to MIT Technology Review. Keith is one of the most well-known names in geoengineering and is part of a Harvard research team that’s been trying to get its own sulfur tests off the ground for years. Nonetheless, Keith is worried by the prospect of privatized, for-profit geoengineering. “Doing it as a startup is a terrible idea,” the scientist said, highlighting the risks of runaway financial motivations.

Geoengineering will almost certainly be part of future climate-focused efforts, whether every expert gets on board or not. The Biden Administration officially approved research funds for solar geoengineering earlier this year. And as the consequences of unabated climate change accelerate, the idea has transitioned from the realm of speculation and science fiction into mainstream discussion. But to prevent solar geoengineering from becoming yet another human-caused climate disaster, much more (and much more careful) research into the strategy is needed.


The solution to climate change is almost certainly not a single maverick “disrupting” the composition of Earth’s stratosphere. But that hasn’t stopped Make Sunsets from reportedly raising nearly $750,000 in funds from venture capital firms. And for just ~$29,250,000 more per year, the company claims it can completely offset current warming. It’s not a bet we recommend taking.