In March 2025, reports emerged about US-Israeli start-up Stardust Solutions pitching its plans to develop and commercialise a highly controversial solar geoengineering technology. It immediately faced objection from the Centre for International Environmental Law (CIEL), as the latter cited the experimentation as a likely violation of the de facto moratorium on geoengineering at the Convention on Biological Diversity.
Stardust is reportedly planning to conduct outdoor tests in Israel, and a governance report commissioned and now endorsed by the start-up disclosed that the company had initiated the process of filing for “relevant intellectual property” rights.
The report further outlined that the company is “developing and testing both a particle and a dispersal system and plans to upgrade the prototype airborne dispersion system to an operational level, enabling dispersion at the required capacity from a future operational aircraft in the coming year.”
The Convention on Biological Diversity, which Israel has been a party to since 2008, has been issuing a series of decisions relating to geoengineering, including a de facto moratorium because of its implications for biodiversity. The moratorium was reaffirmed by consensus at CBD COP16 in Colombia in October–November 2024, with parties citing concern about the increase in outdoor solar and marine geoengineering experiments.
While the moratorium has an exemption for small-scale research, a commercial factor is a key aspect of determining whether or not a project meets the criteria for this exemption. It now remains to be seen whether Stardust’s experimentation will be “small-scale” or not, because if it is not, then it has all the possibilities of being considered a violation of the Convention on Biological Diversity.
What is geoengineering?
The term represents intentional and large-scale manipulative acts committed on our planet Earth. The term is most commonly discussed in the context of climate change. One such technique, “ocean fertilisation,” is the best-studied technique and is the one that is clearly regulated.
The method deals with adding nutrients to ocean waters to increase the phytoplankton population, with the theory propagating that the plankton will absorb carbon dioxide, just as plants do on land. However, ocean fertilisation has been discredited as a climate change response in the scientific literature. Why? Because it is too risky, the effects on the marine food web are unknown, and there is little evidence to prove successful sequestration.
Both the UN Convention on Biological Diversity and the London Convention on Dumping of Waste at Sea prohibit large-scale, open-ocean and/or commercial ocean fertilisation. Only small-scale, legitimate scientific research is allowed, and that too after the successful completion of environmental assessments.
However, Stardust’s geoengineering goals are more ambitious, developing proprietary geoengineering technology that would help block sun rays from reaching the planet.
The start-up, formed in 2023, has a novel approach to private companies, driving the development and deployment of technologies that experts say could have profound consequences for the planet, while going against the trend of most geoengineering research being led by scientists at American universities and federal agencies, and while keeping public scrutiny out of the picture.
Geoengineering projects, even those led by climate scientists, have previously drawn the ire of environmentalists and other groups. In the words of Ramin Skibba, a space writer whose work covers space science, environmentalists, politics, conflicts, and industry, “Such a deliberate transformation of the atmosphere has never been done, and many uncertainties remain. If a geoengineering project went awry, for example, it could contribute to air pollution and ozone loss, or have dramatic effects on weather patterns, such as disrupting monsoons in populous South and East Asia.”
Geoengineering under scrutiny
Global warming has become a hot topic in the current century. As global temperatures rise, public and scientific sentiments are shifting as well. If those temperature trends continue, governments and private entities may ultimately use geoengineering to alleviate or avoid the worst impacts of extreme weather, including deadly heat waves, firestorms, and hurricanes. Whoever deploys the technology will need to maintain it for decades while pent-up greenhouse gases gradually dissipate or are removed.
“Its approach is novel: Most geoengineering research today is led by scientists in the US at universities and federal agencies, and the work they are doing is more or less accessible to public scrutiny. Stardust is at the forefront of an alternative path—one in which private companies drive the development, and perhaps deployment, of technologies that experts say could have profound consequences for the planet,” Skibba noted.
However, environmentalists are sceptical, as a deliberate transformation of the atmosphere has never been done, and from that angle, geoengineering contains many uncertainties. If a project went awry, for example, it could contribute to air pollution and ozone loss, or have dramatic effects on weather patterns, such as disrupting monsoons in populous South and East Asia.
“Few outsiders have gotten a glimpse of Stardust’s plans, and the company has not publicly released details about its technology, its business model, or exactly who works at the company. But the company appears to be positioning itself to develop and sell a proprietary geoengineering technology to governments that are considering making modifications to the global climate—acting like a kind of defence contractor for climate alteration,” Skibba added.
While Stardust is moving ahead with an experiment that has uncertain implications for biodiversity, a lack of rules and limited oversight gives it an upper hand. A recent report by the company’s former climate governance consultant, Janos Pasztor, called for the venture to increase its transparency, engagement, and communication with outsiders.
However, Pasztor also told Undark that the company did not meet all of his requests.
He continued, “Stardust still needs to implement his recommendations, be as transparent as possible, be available proactively to respond to questions people may have, and also engage with other actors, because they do not, or not yet, have a social license for geoengineering activities.”
Stardust solar research
The company discussed by International Finance is led by its CEO and cofounder, Yanai Yedvab, who is also a former deputy chief scientist at the Israel Atomic Energy Commission, which oversees the country’s clandestine nuclear programme. When Undark tried to reach out to Yedvab, he issued an emailed statement, which read: “Stardust is a startup focused on researching and developing technologies that may potentially stop global warming in the short term. The company is studying and developing safe, responsible, and controllable solar radiation modification, and our goal is to enable informed and responsible decision-making by the international community and governments.”
Yedvab further refused to admit that his company is “secretive,” while adding that the startup is “unwaveringly committed to publishing results as one of the measures to gain public trust.”
While Stardust did not publish any of its research data or reports in March 2025, Yedvab stressed that it would do so once “scientific validation is concluded” on all of its results.
When it comes to solar geoengineering, the most common approach has been flying high-altitude aircraft or balloons to release reflective particles in the upper atmosphere, well above the flight paths of commercial planes. The technique, known as stratospheric aerosol injection, requires deploying tiny, carefully chosen particles in precise amounts. To work effectively, the particles need to be periodically replenished. Scientists have accumulated evidence for this approach by studying natural events that have flung small particles into the atmosphere.
The eruption of Mount Pinatubo in 1991 is a good case study, as sulphur dioxide and hydrogen sulphide generated from this phenomenon hung in the atmosphere and measurably cooled the planet for more than a year.
However, research by a team from NASA’s Goddard Institute for Space Studies (GISS) and Columbia University in New York claimed that the sunlight-blocking particles from an extreme eruption would not cool surface temperatures on Earth as severely as previously estimated.
Some 74,000 years ago, the Toba volcano in Indonesia exploded with a force 1,000 times more powerful than the 1980 eruption of Mount St. Helens. What happened afterwards, and to what degree that extreme explosion might have cooled global temperatures, remains a mystery. When it comes to the most powerful volcanoes, researchers have long speculated how post-eruption global cooling, sometimes called volcanic winter, could potentially pose a threat to humanity.
Previous studies agreed that some planet-wide cooling would occur but diverged on how much. The GISS and Columbia University researchers used advanced computer modelling to simulate super-eruptions like the Toba event. They found that post-eruption cooling would probably not exceed 2.7 degrees Fahrenheit (1.5 degrees Celsius) even for the most powerful blasts.
“The relatively modest temperature changes we found, most compatible with the evidence, could explain why no single super-eruption has produced firm evidence of global-scale catastrophe for humans or ecosystems,” said lead author Zachary McGraw, a researcher at NASA GISS and Columbia University.
To qualify as a super-eruption, a volcano must release more than 240 cubic miles (1,000 cubic kilometres) of magma. These eruptions are extremely powerful and rare. The most recent super-eruption occurred more than 22,000 years ago in New Zealand. The most famous example is the eruption that devastated Yellowstone Crater in Wyoming roughly 2 million years ago.
Is deliberately strewing sulphates in the atmosphere a risk worth taking? While some scientists argue that there are indeed risks, they are small in comparison to the health risks from climate change.
“We know that sulphuric acid air pollution causes mortality, and we roughly know how much. There’s more than a century of studies. We’re very unlikely to be wrong about that,” said David Keith, head of the Climate Systems Engineering initiative at the University of Chicago and an advocate of geoengineering research.
Stardust plans to distribute the particles through a machine mounted on an aircraft, according to Pasztor, a veteran climate diplomat and policy expert at the United Nations and elsewhere.
According to Pasztor’s report, the company is engineering the particle and a prototype of the aircraft mount, as well as developing a system for modelling and monitoring the climatic effects. Over the coming year, Pasztor wrote, the company was planning on advancing those technologies and testing those particles in the stratosphere.
In his emailed reply to Undark, Yedvab confirmed that they are working on the technologies and that experiments would be done in a “contained, non-dispersive manner,” meaning that its particles would not be strewn over a wide area.
While reiterating Stardust’s commitment to publishing information about any such outdoor geoengineering tests, the CEO further added that the company has not performed any such outdoor experiments, but has done “a few outdoor aerial checks.” That meant that they have tested their dispersal system “under flight conditions,” but they haven’t yet scattered their aerosols in the atmosphere.
According to Yedvab, Stardust is now testing nonsulfate particles. He continued, “The ability to tailor particle properties to meet a broad set of requirements—safety, effectiveness, cost, and dispersibility—is a key advantage of our approach, giving it a distinct edge over sulphates and other candidate particles.”
Doubts still remain
While the concerns around Stardust’s work may seem justified to some extent, there are no international rules or treaties that put obvious limits on experiments like geoengineering, which could affect billions of lives. Pasztor is advocating for a rule-based order in which more informed experts and stakeholders will be involved in decision-making before the experiment proceeds.
He also believes Stardust has a moral obligation to inform the public about what it is doing and ensure it is receiving input from a wide variety of groups before tinkering with the planetary thermostat. In fact, he stated that Stardust agreed to publish a public website, including a copy of Pasztor’s report, and to develop a voluntary code of conduct.
This would have publicly laid out how they intend to conduct their research and development, including agreeing not to be involved in large-scale implementation, which would instead be under the purview of government agencies. Pasztor expected Stardust to publish this information in September 2024 or soon afterwards. However, the whole plan was “delayed.”
In February 2025, Undark’s website emerged with only three sections to display: Home, Our Principles, and Contact Us. The site also has links to Pasztor’s report and lists seven principles, including “prioritising safety and scientific integrity,” publishing “unfavourable results as well as favourable ones,” and “supporting comprehensive regulation of this emerging field.”
Stardust, however, has not yet released a code of conduct, despite Yedvab stressing that the company complies with all applicable governmental and international regulations.
Stardust’s global role
In Stardust’s portfolio of technologies, Yedvab added, they “could be deployed following decisions by the US government and international community,” suggesting that the startup’s prospective clients will be governments. Even experts believe that Stardust will become a go-to provider for countries considering geoengineering.
The company is attempting to patent its geoengineering technology.
“We anticipate that as US-led geoengineering research and development programmes advance, the value of Stardust’s technological portfolio will grow accordingly,” Yedvab wrote.
Pasztor’s report, however, states that if governments decide not to pursue geoengineering, investors “risk not receiving a return on their investment.”
Other experts have also questioned Stardust’s conduct so far. Among them is Shuchi Talati, founder of The Alliance for Just Deliberation on Solar Geoengineering, a Washington–based nonprofit: “When it comes to principles of governance, like transparency and public engagement, they’re not adhering to any of them. Pasztor’s report is the only public thing we know about them.”
In Talati’s opinion, the lack of transparency could have consequences for the company, as Stardust’s approach may spark conspiracy theories about what a “secret Israeli company” is doing, and, down the road, it will be much harder for people to trust Stardust.
People at Friends of the Earth, an environmental group that has long dismissed geoengineering as a “dangerous distraction,” echo Talati’s concerns and go further with their critiques of Stardust.
“I don’t think it’s compatible to have venture capital funding and to be committed to scientific ideals,” said Benjamin Day, FOE’s senior campaigner on geoengineering.
He believes the problem lies in Stardust’s engineers having a vested interest in finding that stratospheric geoengineering can and should be done.
“If governments choose to use geoengineering, they may become heavily dependent on Stardust if they’re ahead of the competition, of which there currently is none. There’s no private market for geoengineering technologies. They’re only going to make money if it’s deployed by governments, and at that point they’re kind of trying to hold governments hostage with technology patents,” Benjamin Day added.
Talking about government-level projects, the United States government is developing an early warning system that could detect geoengineering in the stratosphere. Furthermore, deploying geoengineering means using and monitoring it for as long as a century, while any abrupt adjustment or end of that deployment could be disruptive, with “termination shock” potentially triggering dangerous global warming within months.
“Geoengineering research has long been entangled with national defence,” said Kevin Surprise, a professor of environmental studies at Mount Holyoke College who studies the economics and geopolitics of geoengineering.
“Some of the first geoengineering papers in the late 1990s came from institutions with Pentagon ties, like Lawrence Livermore National Lab and the Hoover Institution. High-profile geoengineering meetings with the George W Bush administration and the Council on Foreign Relations, as well as a mention in a Department of Defence report, soon followed, and the CIA reportedly funded the first geoengineering report from the National Academies of Sciences, Engineering, and Medicine. Because of the long-standing connections between geoengineering research and development, the military, and Silicon Valley, Surprise argues, Stardust shouldn’t be viewed as a rogue actor. This isn’t out of the blue,” he noted.
In Stardust’s case, they’ve received an estimated $15 million in venture capital funding, mainly from Awz Ventures, a Canadian-Israeli VC firm, in addition to a small investment from SolarEdge, an Israeli energy company. Despite the startup claiming that it has received no monetary help from the Israeli Defence Ministry, Awz’s partners and strategic advisers have strong ties to Israeli military and intelligence agencies, as well as the CIA and FBI, according to its website. Awz also invests in AI-based surveillance and security tech in Israel, such as through the company Corsight, which has provided facial recognition technology for Israel’s war in Gaza.
“Defence scholars and security experts don’t see geoengineering technology as a potential weapon, but they do view it as something a government might use for its advantage, and as something that would disrupt international relations,” said Duncan McLaren, a researcher with the Institute for Responsible Carbon Removal at American University.