A VC-backed Venture Is Spreading Pollutants into the Stratosphere to Partially Block Sunlight: What Could Possibly Go Wrong?
When Luke Iseman and Andrew Song founded Make Sunsets, they didn’t wait for permission to start "cooling the planet." From a patch of land in California and the back of an RV they call “Hotpot Song Force One,” the duo began launching balloons filled with sulfur dioxide (SO₂) into the stratosphere, claiming each release would reflect sunlight and combat global warming.
Fueled by nearly $1 million in venture capital from heavyweights like Draper Associates and Boost VC, Make Sunsets embodies a bold, dangerous, approach to climate activism. Their product? Unverified "cooling credits," sold to customers eager to offset carbon footprints with a technology many scientists warn is experimental at best, catastrophic at worst.
What began as a rogue startup’s attempt to hack the climate has now drawn the scrutiny of the U.S. Environmental Protection Agency (EPA), which says it never approved such efforts and is demanding answers.
EPA Investigates Make Sunsets: The Agency Has No Clear Understanding of the Startup’s “Questionable” Activities
On April 14, 2025, the EPA issued a formal investigation letter to Iseman and Song, citing potential violations of the Clean Air Act. The agency’s concerns center on Make Sunsets’ multiple balloon launches, which exceed 130 balloons, conducted without permits, environmental review, or coordination with federal authorities.
In its statement, the EPA made clear that sulfur dioxide isn’t a harmless tool for climate intervention; it’s a regulated pollutant known to harm human health and the environment. EPA Administrator Lee Zeldin called the company’s actions "deeply irresponsible," emphasizing that "unauthorized geoengineering experiments pose unpredictable risks."
Zeldin was quoted on the EPA’s website,
“The idea that individuals, supported by venture capitalists, are putting criteria air pollutants into the air to sell ‘cooling’ credits shows how climate extremism has overtaken common sense,” said EPA Administrator Zeldin. “Based on Make Sunsets’ responses to our information request, we will look into all our authorities to ensure that we continue maintaining clean air for all Americans.”
The agency’s inquiry letter to the startup demands everything from chemical data and launch logs to evidence of safety protocols. Failure to comply could result in hefty fines or legal action.
On their website, the EPA cites Section 114 of the Clean Air Act as their legal authority to investigate,
This isn’t the first time Make Sunsets has faced backlash. After early launches in Mexico, the country swiftly banned all geoengineering experiments, citing national security concerns and environmental dangers. Now, U.S. regulators are questioning how a VC-backed startup has assumed free rein to tamper with natural atmospheric systems.
“Under Section 114 of the Clean Air Act (CAA), EPA is authorized to require facilities to provide information about their operations.
“The agency is requesting a response within 30 days.
“Sulfur dioxide has been regulated by EPA since 1971 as part of the National Ambient Air Quality Standard (NAAQS) program. Sulfur dioxide can harm human health and the environment. Short-term exposures to SO2 can harm the human respiratory system and make breathing difficult. People with pulmonary diseases, particularly children, are sensitive to the effects of SO2. Additionally, SO2 can react in the atmosphere leading to acid rain or form particles that harm health and impair visibility.”
(Below) The EPA Office of Air and Radiation's letter to Make Sunset's founders Luke Iseman and Andrew Song. Click image to read.
“This company is polluting the air we breathe”
In a separate post on X.com, Zeldin openly chastises the company, stating:
“Make Sunsets is a startup that is geoengineering by injecting sulfur dioxide into the sky and then selling “cooling credits.” This company is polluting the air we breathe. I’ve instructed my team that we need to quickly get to the bottom of this and take immediate action.”
Make Sunsets is a startup that is geoengineering by injecting sulfur dioxide into the sky and then selling “cooling credits.” This company is polluting the air we breathe. I’ve instructed my team that we need to quickly get to the bottom of this and take immediate action. pic.twitter.com/9b6xPzMf4v
— Lee Zeldin (@epaleezeldin) April 15, 2025
Silicon Valley’s “Move Fast and Break Things” Ethos Goes Global
Make Sunsets is a textbook case of Silicon Valley ambition colliding with law and ethics. Backed by Tim Draper and his son Adam Draper, and investors from Pioneer Fund, the startup secured funding before it even had paying customers.
Their pitch was simple: for a few dollars, companies could buy cooling credits by paying Make Sunsets to inject sulfur dioxide into the stratosphere. The founders claim this process mimics volcanic eruptions like Mount Pinatubo’s in 1991, which temporarily cooled global temperatures.
But scientists warn that imitating nature isn’t so straightforward. Unlike a one-time volcanic event, stratospheric aerosol injection (SAI) would require constant, indefinite deployment to maintain cooling effects. Sudden cessation could trigger what's known as termination shock, a rapid spike in global temperatures with devastating consequences.
Despite these warnings, founders of Make Sunsets remain defiant. They argue that doing nothing is more dangerous and they dismiss critics who label their work as ‘reckless.’
Playing Russian Roulette with the Earth's Climate: Critics Sound the Alarm
Environmental experts and policymakers are raising serious concerns about the precedent Make Sunsets is setting. Professor David Keith, a vocal figure on the idea of solar geoengineering, has cautioned that while SAI might reduce temperatures, it also risks disrupting weather patterns, including monsoons and food production systems.
The lack of international governance adds fuel to the criticism. With no global framework to regulate geoengineering, small companies like Make Sunsets are effectively making planetary decisions on behalf of billions of people and doing so without consent.
Another critic calls it climate “colonialism,” where entrepreneurs in privileged nations gamble with technologies that could disproportionately harm vulnerable regions.
The Bloomberg Originals report,“The Risky Business of Geoengineering,” highlighted how Make Sunsets’ venture blurs the line between innovation and environmental recklessness, noting that the company’s only barrier to scaling operations is "demand." It seems they currently have a lack of it.
Climate "Innovation" Without Oversight: A Warning Sign for the Rest of Us
As federal investigators begins to scrutinize, Make Sunsets increasingly resembles a pair of high-tech snake oil salesmen, selling slick promises without any tangible product. Their so-called “Cooling Credits” have no grounding in any recognized market, no regulatory oversight, and no proven environmental benefit.
Is this a reckless scheme guised in climate rhetoric?
The venture flirts with fraud. In Silicon Valley, they have a name for this kind of scheme: “vaporware.” It’s a fitting term in this case since Making Sunsets is literally selling aerosol.
In the meantime, as the company continues to play Russian roulette with the world’s atmosphere, the rest of us are left to wonder: will the next balloon launch be the one that goes disastrously wrong?
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