A Nonprofit Wants to Spray 25,000 Tons of Sulfur Dioxide; It Calls That “Research,” Not Deployment

A San Francisco nonprofit called Reflective has published a plan to spray sulfur dioxide into the stratosphere, first by the ton and later by the thousands of tons, and to treat the result as a research step toward “monitored cooling” of the planet. The company said it does not advocate “deployment,” but they are advocating for research that includes 25,000 ton seasonal releases of sulphur dioxide as phase two of the process. Phase three would depend on how the results of the “research,” and would be a deliberate ramp-up of sulfur dioxide releases with an intention to cool the environment.

Wil Burns, a research professor and legal scholar at American University, warns of a termination shock if sulfur dioxide was released purposefully into the environment to mask the effects of continued emitting greenhouse gases. “What that would do, in my mind, is put a sword of Damocles over future generations,” he says. “So even if you could, quote-unquote, ‘prove it works,’ I don’t think from an intergenerational perspective it would ever be tenable.”

Burns is one of more than 650 scholars who have signed onto a global initiative calling for an International Non-Use Agreement on Solar Geoengineering. He said the research that Reflective is advocating for would give answers about the deployment of sulfur dioxide into the environment, but not the answers that are most relevant to the question.

Reflective released its roadmap on September 10, 2026, which would dramatically scale up the geoengineering efforts that are already being deployed on a much smaller scale. The EPA under the leadership of Administrator Lee Zeldin has released information that the agency has regarding solar geoengineering and issued a letter to a for-profit company called Make Sunsets, which has been releasing about 0.1 tons into the stratosphere. Zeldin was seeking answers on whether the EPA or other government agencies have the authority to halt the activity, but it doesn’t appear the agency has the authority based on the current information.

Reflective, meanwhile, has laid out a framework that looks to rapidly expand the “research” into the technology of solar geoengineering with a roadmap to deployment for “monitored cooling” of the atmosphere.

More than $20 million has been raised by Reflective since the company was incorporated in late 2023. Chief executive Dakota Gruener says the mission is “to equip the world with the data and tools required for informed decision-making about sunlight reflection fast enough to matter.” The roadmap does not name its donors.

The plan is staged like a drug trial. Phase 0 is models, laboratory work, and volcanic records. The next stage uses modified aircraft to release 10 metric tons of sulfur dioxide, four times over two seasons. Reflective says that is small enough to have no cooling effect, and less than 2 percent of one day’s aviation emissions.

The phase after that is 25,000 tons over a single season, at least once and possibly twice. The final phase is monitoring if full-scale spraying proceeds. Reflective estimates this will take a decade and about $370 million. Its own site puts an informed decision on “monitored cooling” at 10 to 22 years and $370 million to $1.36 billion. Gruener says the gates exist “precisely because there may be points where the answer is ‘You should stop.’” She also says the alternative is “decisions being made in a panic or on lack of evidence.”

Public consent is not named anywhere in the document. The roadmap makes no mention of government overview, liability, or who would authorize a release. The “stage gates” are scientific criteria set by the researchers with no public involvement. Aarti Gupta, a co-initiator of the Non-Use Agreement argues the open questions are who would control it and whose purposes it would serve. Burns said the Reflective’s roadmap and research would not answer the important questions regarding potential downsides, including ozone and regional rainfall, and the potential for termination shock.

These companies are arguing that solar geoengineering is a potential fix to a problem that many people say doesn’t even exist. Jefferey Jaxen reported for The HighWire in February about the claims that were made in Al Gore’s documentary “An Inconvenient Truth” that turned out to be false. That film was released 20 years ago and brought significantly more attention to the claims of global warming and climate change as an existential threat.

Bill Gates, in 2021, said he agreed with President Joe Biden who said the US “must lead the world to take on the existential threat” of climate change. Last year, Gates changed his tone and said, “it will not lead to humanity’s demise. People will be able to live and thrive in most places on Earth for the foreseeable future.” Gates said preventing disease and poverty should be the primary focus rather than emissions and temperature.

Make Sunsets sent an email to subscribers on October 1 stating, “Weather is getting even weirder, fast. And, we don’t have sensor infrastructure that’s cheap, accurate, and fast to deploy. Our first draft at fixing this is getting fabricated now and will be ready for sale within a few months. Let’s understand climate better as we fix it!”

While Make Sunsets only released 0.1 tons of sulfur dioxide as of May 2025, Reflective’s roadmap calls for four releases of 10 metric tons, which is 400 times larger than the amount the EPA said Make Sunsets released. The next phase after that is 25,000 tons in one season. Reflective says “Stratospheric Aerosol Injection (SAI) may be the only practical near-term option to mitigate many potentially devastating climate impacts in the next few decades, and allow the necessary time for more permanent climate solutions and decarbonization to take hold.”