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“I am increasingly becoming irrelevant in the public conversation,” says Kate Marvel, a climate scientist who until recently worked at NASA’s Goddard Institute for Space Studies. “And I love it.”
For years, such an exalted state was denied to Marvel. Every week, it seemed, someone — a high-profile politician, maybe, or a CEO — would say something idiotic about climate science. Journalists would dutifully call her to get a rebuttal: Yes, climate change is real, she would say, yes, we’re really certain. The media would print the story. Rinse, repeat.
A few years ago, she told a panel, half as a joke, that her highest professional ambition was not fame or a Nobel Prize but total irrelevance — a moment when climate scientists would no longer have anything useful to tell the public.
That 2020 dream is now her 2023 reality. “It’s incredible,” she told me last week. “Science is no longer even a dominant part of the climate story anymore, and I think that’s great. I think that represents just shattering progress.”
We were talking about a question, a private heresy, I’ve been musing about for some time. Because it’s not just the scientists who have faded into the background — over the past few years, the role of climate science itself has shifted. Gradually, then suddenly, a field once defined by urgent questions and dire warnings has become practical and specialized. So for the past few weeks, I’ve started to ask researchers my big question: Have we reached the end of climate science?
“Science is never done,” Michael Oppenheimer, a professor of geosciences and international affairs at Princeton, told me. “There’s always things that we thought we knew that we didn’t.”
“Your title is provocative, but not without basis,” Katharine Hayhoe, a climate scientist at Texas Tech University and one of the lead authors of the National Climate Assessment, said.
Not necessarily no, then. My question, I always clarified, had a few layers.
Since it first took shape, climate science has sought to answer a handful of big questions: Why does Earth’s temperature change so much across millennia? What role do specific gases play in regulating that temperature? If we keep burning fossil fuels, how bad could it be — and how hot could it get?
The field has now answered those questions to any useful degree. But what’s more, scientists have advocated and won widespread acceptance of the idea that inevitably follows from those answers, which is that humanity must decarbonize its economy as fast as it reasonably can. Climate science, in other words, didn’t just end. It reached its end — its ultimate state, its Really Big Important Point.
In the past few years, the world has begun to accept that Really Big Important Point. Since 2020, the world’s three largest climate polluters — China, the United States, and the European Union — have adopted more aggressive climate policies. Last year, the global clean-energy market cracked $1 trillion in annual investment for the first time; one of every seven new cars sold worldwide is now an electric vehicle. In other words, serious decarbonization — the end of climate science — has begun.
At the same time, climate science has resolved some of its niggling mysteries. When I became a climate reporter in 2015, questions still lingered about just how bad climate change would be. Researchers struggled to understand how clouds or melting permafrost fed back into the climate system; in 2016, a major paper argued that some Antarctic glaciers could collapse by the end of the century, leading to hyper-accelerated sea-level rise within my lifetime.
Today, not all of those questions have been completely put aside. But scientists now have a better grasp of how clouds work, and some of the most catastrophic Antarctic scenarios have been pushed into the next century. In 2020, researchers even made progress on one of the oldest mysteries in climate science — a variable called “climate sensitivity” — for the first time in 41 years.
Does the field have any mysteries left? “I wouldn’t go quite so far as angels dancing on the head of a pin” to describe them, Hayhoe told me. “But in order to act, we already know what we need.”
“I think at the macro level, what we discover [next] is not necessarily going to change policymakers’ decisions, but you could argue that’s been true since the late 90s,” Zeke Hausfather, a climate scientist at Berkeley Earth, agreed.
“Physics didn’t end when we figured out how to do engineering, and now they are both incredibly important,” Marvel said.
Yet across the discipline, you can see research switching their focus from learning to building — from physics, as it were, to engineering. Marvel herself left NASA last year to join Project Drawdown, a nonprofit that focuses on emissions reduction. Hausfather now works at Frontier, a tech-industry consortium that studies carbon-removal technology. Even Hayhoe — who trained as a climate scientist — joined a political-science department a decade ago. “I concluded that the biggest barriers to action were not more science,” she said this week.
To fully understand whether climate science has ended, it might help to go back to the very beginning of the field.
By the late 19th century, scientists knew that Earth was incredibly ancient. They also knew that over long enough timescales, the weather in one place changed dramatically. (Even the ancient Greeks and Chinese had noticed misplaced seashores or fossilized bamboo and figured out what they meant.) But only slowly did questions from chemistry, physics, and meteorology congeal into a new field of study.
The first climate scientist, we now know, was Eunice Newton Foote, an amateur inventor and feminist. In 1856, she observed that glass jars filled with carbon dioxide or water vapor trapped more of the sun’s heat than a jar containing dry air. “An atmosphere of that gas,” she wrote of CO₂, “would give to our earth a high temperature.”
But due to her gender and nationality, her work was lost. So the field began instead with the contributions of two Europeans: John Tyndall, an Irish physicist who in 1859 first identified which gases cause the greenhouse effect; and Svante Arrhenius, a Swedish chemist who in 1896 first described Earth’s climate sensitivity, perhaps the discipline’s most important number.
Arrhenius asked: If the amount of CO₂ in the atmosphere were to double, how much would the planet warm? Somewhere from five to six degrees Celsius, he concluded. Although he knew that humanity’s coal consumption was causing carbon pollution, his calculation was a purely academic exercise: We would not double atmospheric CO₂ for another 3,000 years.
In fact, it might take only two centuries. Atmospheric carbon-dioxide levels are now 50 percent higher than they were when the Industrial Revolution began — we are halfway to doubling.
Not until after World War II did climate science become an urgent field, as nuclear war, the space race, and the birth of environmentalism forced scientists to think about the whole Earth system for the first time — and computers made such a daring thing possible. In the late 1950s and 1960s, the physicists Syukuro Manabe and Richard Wetherald produced the first computer models of the atmosphere, confirming that climate sensitivity was real. (Last year, Manabe won the Nobel Prize in Physics for that work.) Half a hemisphere away, the oceanographer Charles Keeling used data collected from Hawaii’s Mauna Loa Observatory to show that fossil-fuel use was rapidly increasing the atmosphere’s carbon concentration.
Suddenly, the greenhouse effect — and climate sensitivity — were no longer theoretical. “If the human race survives into the 21st century,” Keeling warned, “the people living then … may also face the threat of climatic change brought about by an uncontrolled increase in atmospheric CO₂ from fossil fuels.”
Faced with a near-term threat, climate science took shape. An ever-growing group of scientists sketched what human-caused climate change might mean for droughts, storms, floods, glaciers, and sea levels. Even oil companies opened climate-research divisions — although they would later hide this fact and fund efforts to discredit the science. In 1979, the MIT meteorologist Jules Charney led a national report concluding that global warming was essentially inevitable. He also estimated climate sensitivity at 1.5 to 4 degrees Celsius, a range that would stand for the next four decades.
“In one sense, we’ve already known enough for over 50 years to do what we have to do,” Hayhoe, the Texas Tech professor, told me. “Some parts of climate science have been simply crossing the T’s and dotting the I’s since then.”
Crossing the T’s and dotting the I’s—such an idea would have made sense to the historian Thomas Kuhn. In his book, The Structure of Scientific Revolutions, he argued that science doesn’t progress in a dependable and linear way, but through spasmodic “paradigm shifts,” when a new theory supplants an older one and casts everything that scientists once knew in doubt. These revolutions are followed by happy doldrums that he called “normal science,” where researchers work to fit their observations of the world into the moment’s dominant paradigm.
By 1988, climate science had advanced to the degree that James Hansen, the head of NASA’s Goddard Institute, could confidently warn the Senate that global warming had begun. A few months later, the United Nations convened the first Intergovernmental Panel on Climate Change, an expert body of scientists asked to report on current scientific consensus.
Yet core scientific questions remained. In the 1990s, the federal scientist Ben Santer and his colleagues provided the first evidence of climate change’s “fingerprint” in the atmosphere — key observations that showed the lower atmosphere was warming in such a way as to implicate carbon dioxide.
By this point, any major scientific questions about climate change were effectively resolved. Paul N. Edwards, a Stanford historian and IPCC author, remembers musing in the early 2000s about whether the IPCC’s physical-science team should pack it up: They had done the job and shown that climate change was real.
Yet climate science had not yet won politically. Santer was harassed over his research; fossil-fuel companies continued to seed lies and doubt about the science for years. Across the West, only some politicians acted as if climate change was real; even the new U.S. president, Barack Obama, could not get a climate law through a liberal Congress in 2010.
It took one final slog for climate science to win. Through the 2010s, scientists ironed out remaining questions around clouds, glaciers, and other runaway feedbacks. “It’s become harder in the last decade to make a publicly skeptical case against mainstream climate science,” Hausfather said. “Part of that is climate science advancing one funeral at a time. But it’s also become so clear and self-evident — and so much of the scientific community supports it — that it’s harder to argue against with any credibility.”
Three years ago, a team of more than two dozen researchers — including Hausfather and Marvel — finally made progress on solving climate science’s biggest outstanding mystery, cutting our uncertainty around climate sensitivity in half. Since 1979, Charney’s estimate had remained essentially unchanged; it was quoted nearly verbatim in the 2013 IPCC report. Now, scientists know that if atmospheric CO₂ were to double, Earth’s temperature would rise 2.6 to 3.9 degrees Celsius.
That’s about as much specificity as we’ll ever need, Hayhoe told me. Now, “we know that climate sensitivity is either bad, really bad, or catastrophic.”
So isn’t climate science over, then? It’s resolved the big uncertainties; it’s even cleared up climate sensitivity. Not quite, Marvel said. She and other researchers described a few areas where science is still vital.
The first — and perhaps most important — is the object that covers two-thirds of Earth’s surface area: the ocean, Edwards told me. Since the 1990s, it has absorbed more than 90% of the excess heat caused by greenhouse gases, but we still don’t understand how it formed, much less how it will change over the next century.
Researchers also know some theories need to be revisited. “Antarctica is melting way faster than in the models,” Marvel said, which could change the climate much more quickly than previously imagined. And though the runaway collapse of Antarctica now seems less likely, we could be wrong, Oppenheimer reminded me. “The money that we put into understanding Antarctica is a pittance compared to what you would need to truly understand such a big object,” he said.
And these, mind you, are the known unknowns. There’s still the chance that we discover some huge new climatic process out there — at the bottom of the Mariana Trench, perhaps, or at the base of an Antarctic glacier — that has so far eluded us.
Yet in the wildfires of the old climate science, a new field is being born. The scientists who I spoke with see three big projects.
First, in the past decade, researchers have gotten much better at attributing individual weather events to climate change. They now know that the Lower 48 states are three times more likely to see a warm February than they would without human-caused climate change, for instance, or that Oregon and Washington’s record-breaking 2021 heat wave was “virtually impossible” without warming. This work will keep improving, Marvel said, and it will help us understand where climate models fail to predict the actual experience of climate change.
Second, scientists want to make the tools of climate science more useful to people at the scales where they live, work, and play. “We just don’t yet have the ability to understand in a detailed way and at a small-enough scale” what climate impacts will look like, Oppenheimer told me. Cities should be able to predict how drought or sea-level rise will affect their bridges or infrastructure. Members of Congress should know what a once-in-a-decade heat wave will look like in their district five, 10, or 20 years hence.
“It’s not so much that we don’t need science anymore; it’s that we need science focused on the questions that are going to save lives,” Oppenheimer said. The task before climate science is to steward humanity through the “treacherous next decades where we are likely to warm through the danger zone of 1.5 degrees.”
That brings us to the third project: That climatologists must create a “smoother interface between physical science and social science,” he said. The Yale economist Richard Nordhaus recently won a Nobel Prize for linking climate science with economics, “but other aspects of the human system are still totally undone.” Edwards wanted to get beyond economics altogether: “We need an anthropology and sociology of climate adaptation,” he said. Marvel, meanwhile, wanted to zoom the lens beyond just people. “We don’t really understand ... what the hell plants do,” she told me. Plants and plankton have absorbed half of all carbon pollution, but it’s unclear if they’ll keep doing so or how all that extra carbon has changed how they might respond to warming.
Economics, sociology, botany, politics — you can begin to see a new field taking shape here, a kind of climate post-science. Rooted in climatology’s theories and ideas, it stretches to embrace the breadth of the Earth system. The climate is everything, after all, and in order to survive an era when human desire has altered the planet’s geology, this new field of study must encompass humanity itself — and all the rest of the Earthly mess.
Nearly a century ago, the philosopher Alexander Kojéve concluded it was possible for political philosophy to gain a level of absolute knowledge about the world and, second, that it had done so. In the wake of the French Revolution, some fusion of socialism or capitalism would win the day, he concluded, meaning that much of the remaining “work to do” in society lay not in large-scale philosophizing about human nature, but in essentially bureaucratic questions of economic and social governance. So he became a technocrat, and helped design the market entity that later became the European Union.
Is this climate science’s Kojéve era? It just may be — but it won’t last forever, Oppenheimer reminded me.
“Generations in the future will still be dealing with this problem,” he said. “Even if we get off fossil fuels, some future idiot genius will invent some other climate altering substance. We can never put climate aside — it’s part of the responsibility we inherited when we started being clever enough to invent problems like this in future.”
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A U.S. firm led by former Israeli government physicists, Stardust seeks to patent its proprietary sunlight-scattering particle — but it won’t deploy its technology until global governments authorize such a move, its CEO says.
The era of the geoengineering startup has seemingly arrived.
Stardust Solutions, a company led by a team of Israeli physicists, announced on Friday that it has raised $60 million in venture capital to develop technological building blocks that it says will make solar geoengineering possible by the beginning of next decade.
It is betting that it can be the first to develop solar geoengineering technology, a hypothetical approach that uses aerosols to reflect sunlight away from Earth’s surface to balance out the effects of greenhouse gases. Yanai Yedvab, Stardust’s CEO, says that the company’s technology will be ready to deploy by the end of the decade.
The funding announcement represents a coming out of sorts for Stardust, which has been one of the biggest open secrets in the small world of solar geoengineering researchers. The company is — depending on how you look at it — either setting out a new way to research solar radiation management, or SRM, or violating a set of informal global norms that have built up to govern climate-intervention research over time.
Chief among these: While universities, nonprofits, and government labs have traditionally led SRM studies, Stardust is a for-profit company. It is seeking a patent for aspects of its geoengineering system, including protections for the reflective particles that it hopes governments will eventually disperse in the atmosphere.
The company has sought the advice of former United Nations diplomats, federal scientists, and Silicon Valley investors in its pursuit of geoengineering technology. Lowercarbon Capital, one of the most respected climate tech venture capital firms, led the funding round. Stardust previously raised a seed round of $15 million from Canadian and Israeli investors. It has not disclosed a valuation.
Yedvab assured me that once Stardust’s geoengineering system is ready to deploy, governments will decide whether and when to do so.
But even if it is successful, Stardust’s technology will not remove climate risk entirely. “There will still be extreme weather events. We’re not preventing them altogether,” Yedvab said. Rather, tinkering with the Earth’s atmosphere on a planetary scale could help preserve something like normal life — “like the life that all of us, you, us, our children have been experiencing over the last few decades.” The new round of funding, he says, will put that dream within reach.
Yedvab, 54, has salt and pepper hair and a weary demeanor. When I met him earlier this month, he and his cofounder, Stardust Chief Product Officer Amyad Spector, had just flown into New York from Tel Aviv, before continuing on to Washington, D.C., that afternoon. Yedvab worked for many years at the center of the Israeli scientific and defense establishment. From 2011 to 2015, he was the deputy chief research scientist at the Israeli Atomic Energy Commission. He was also previously the head of the physics division at the highly classified Israeli nuclear research site in Negev, according to his LinkedIn.
Spector, 42, has also spent much of his career working for the Israeli government. He was a physics researcher at the Negev Nuclear Research Center before working on unspecified R&D projects for the government for nearly a decade, as well as on its Covid response. He left the government in December 2022.
Stardust’s story, in their telling, began in the wake of the pandemic, when they and their third cofounder — Eli Waxman, a particle physics professor at the Weizmann Institute of Science — became curious about climate change. “We started [with a] first principles approach,” Yedvab told me. What were countries’ plans to deal with warming? What did the data say? It was a heady moment in global climate politics: The United States and Europe had recently passed major climate spending laws, and clean energy companies were finally competing on cost with oil and gas companies.
Yet Yedvab was struck by how far away the world seemed to be from meeting any serious climate goal. “I think the thing that became very clear early on is that we’re definitely not winning here, right?” he told me. “These extreme weather events essentially destroy communities, drain ecosystems, and also may have major implications in terms of national security,” he said. “To continue doing what we’re doing over the next few decades and expecting materially different results will not get us where we want to be. And the implications can be quite horrific.”
Then they came across two documents that changed their thinking. The first was a 2021 report from the National Academies of Sciences in the United States, which argued that the federal government should establish “a transdisciplinary, solar geoengineering research program” — although it added that this must only be a “minor part” of the country’s overall climate studies and could not substitute for emissions reductions. Its authors seemed to treat solar geoengineering as a technology that could be developed in the near term, akin to artificial intelligence or self-driving cars.
They also found a much older article by the physicist Edward Teller — the same Teller who had battled with J. Robert Oppenheimer during the Manhattan Project. Teller had warned the oil industry about climate change as early as 1959, but in his final years he sought ways to avoid cutting fossil fuels at all. Writing in The Wall Street Journal weeks before the Kyoto Protocol meetings in 1997, an 89-year-old Teller argued that “contemporary technology offers considerably more realistic options for addressing any global warming effect” than politicians or activists were considering.
“One particularly attractive approach,” he wrote, was solar geoengineering. Blocking just 1% of sunlight could reduce temperatures while costing $100 million to $1 billion a year, he said, a fraction of the estimated societal cost of paring fossil fuels to their 1990 levels. A few years later, he wrote a longer report for the Energy Department arguing for the “active technical management” of the atmosphere rather than “administrative management” of fossil fuel consumption. He died in 2003.
The documents captivated the two scientists. What began to appeal to Yedvab and Spector was the economy of scale unlocked by the stratosphere — the way that just a few million tons of material could change the global climate. “It's very easy to understand why, if this works, the benefit could be enormous,” Yedvab said. “You can actually stop global warming. You can cool the planet and avoid a large part of the suffering. But then again, it was a very theoretical concept.” They incorporated Stardust in early 2023.
Economists had long anticipated the appeal of such an approach to climate management. Nearly two decades ago, the Columbia economist Scott Barrett observed that solar geoengineering’s economics are almost the exact opposite of climate change’s: While global warming is a “free rider” problem, where countries must collaborate to avoid burning cheap fossil fuels, solar geoengineering is a “free driver” problem, where one country could theoretically do it alone. Solar geonengineering’s risks lay in how easy it would be to do — and how hard it would be to govern.
Experts knew how you would do it, too: You would use sulfate aerosols — the tiny airborne chemicals formed when sulfur from volcanoes or fossil fuels reacts with water vapor, oxygen, and other substances in the air. In a now classic natural experiment Teller cited in his Journal op-ed, when Mount Pintabuo erupted in 1991 in the Philippines, it hurled a 20 million ton sulfur-dioxide cloud into the stratosphere, cooling the world by up to 1.3 degrees Fahrenheit before the sulfates rained out.
But to Yedvab, “sulfates look like a poor option,” he told me. Sulfates and sulfur oxides are nasty pollutants in their own right — they can cause asthma attacks, form acid rain, and may damage the ozone layer when in the stratosphere. For this reason, the International Maritime Organization adopted new rules restricting the amount of sulfur in cargo shipping fuels; these rules — in yet another natural experiment — seem to have accidentally accelerated global warming since 2020.
Yedvab and Spector anticipated another problem with sulfates: The atmosphere already contains tens of millions of tons of them. There is already so much sulfate in the sky from natural and industrial processes, they argue, that scientists would struggle to monitor whatever was released by geoengineers; Spector estimates that the smallest potential geoengineering experiment would require emitting 1 million tons of it. The chemical seemed to present an impossible trade-off to policymakers: How could a politician balance asthma attacks and acid rain against a cooler planet? “This is not something that decisionmakers can make a decision about,” Yedvab concluded.

Instead, the three founders tried starting at the end of the process, as they put it. What would an ideal geoengineering system look like? “Let’s say that we are successful in developing a system,” Yedvab said. “What will be the questions that people like you — that policymakers, the general public — will ask us?”
Any completed geoengineering system, they concluded, would need to meet a few constraints. It would need, first, a particle that could reflect a small amount of sunlight away from Earth while allowing infrared radiation from the planet’s surface to bounce back into space. That particle would need to be tested iteratively and manufactured easily in the millions of tons, which means it would also have to be low-cost.
“This needs to be a scalable or realistic particle that we know from the start how to produce at scale in the millions of tons, and at the relevant target price of a few dollars per kilo,” Yedvab said. “So not diamonds or something that we've done at the lab but have no idea how to scale it up,” Yedvab said.
It would need to be completely safe for people and the biosphere. Stardust hopes to run its particle through a safety process like the ones that the U.S. and EU subject food or other materials to, Yedvab said. “This needs to be as safe as, say, flour or some food ingredient,” Yedvab said. The particle would also need to be robust and inert in the stratosphere, and you would need some way to manage and identify it, perhaps even to track it, once it got there.
Second, the system would need some way to “loft” that particle into the stratosphere — some machine that could disperse the particle at altitude. Finally, it would need some way to make the particles observable and controllable, to make sure they are acting as intended. “For visibility, for control, for, I would say, geopolitical implications — you want to make sure you actually know where, how these particles move around, Yedvab said.
Stardust received $15 million in seed funding from the venture firm AWZ and Solar Edge, an Israeli energy company, in early 2024. Soon after, the founders got to work.
The world has come close to solving a global environmental crisis at least once before. In 1987, countries adopted the Montreal Protocol, which set out rules to eliminate and replace the chlorofluorocarbons that were destroying the stratospheric ozone hole. Nearly 40 years later, the ozone hole is showing signs of significant recovery. And more to the point, almost nobody talks about the ozone hole anymore, because someone else is dealing with it.
“I would say it was the biggest triumph of environmental diplomacy ever,” Yedvab said. “In three years, beginning to end, the U.S. government was able to secure the support of essentially all the major powers in solving a global problem.” The story is not quite that simple — the Reagan administration initially resisted addressing the ozone hole until American companies like DuPont stood to benefit by selling non-ozone-depleting chemicals — but it captures the kind of triumphant U.S.-led process that Stardust wouldn’t mind seeing repeated.
In 2024, soon after Stardust raised its seed round, Yedvab approached the Swiss-Hungarian diplomat Janos Pasztor and invited him to join the company to advise on the thicket of issues usually simplified as “governance.” These can include technical-seeming questions about how companies should test their technology and who they should seek input from, but they all, at their heart, get to the fundamentally undemocratic nature of solar geoengineering. Given that the atmosphere is a global public good, who on Earth has the right to decide what happens to it?
Pasztor is the former UN assistant secretary-general for climate change, but he was also the longtime leader of the Carnegie Climate Governance Initiative, a nonprofit effort to hammer out consensus answers to some of those questions.
Pasztor hesitated to accept the request. “It was a quadruple challenge,” he told me, speaking from his study in Switzerland. He and his wife frequently attend pro-Palestine demonstrations, he said, and he was reluctant to work with anyone from Israel as long as the country continued to occupy Gaza and the West Bank. Stardust’s status as a private, for-profit enterprise also gave him pause: Pasztor has long advocated for SRM research to be conducted by governments or academics, so that the science can happen out in the open. Stardust broke with all of that.
Despite his reservations, he concluded that the issue was too important — and the lack of any regulation or governance in the space too glaring — for him to turn the company away. “This is an issue that does require some movement,” he said. “We need some governance for the research and development of stratospheric aerosol injection … We don’t have any.”
He agreed to advise Stardust as a contractor, provided that he could publish his report on the company independently and donate his fee to charity. (He ultimately gave $27,000 to UNRWA, the UN agency for Palestinian refugees.)
That summer, Pasztor completed his recommendations, advising Stardust — which remained in stealth mode — to pursue a strategy of “maximum transparency” and publish a website with a code of conduct and some way to have two-way conversations with stakeholders. He also encouraged the company to support a de facto moratorium on geoengineering deployment, and to eventually consider making its intellectual property available to the public in much the same way that Volvo once opened its design for the three-point seatbelt.
His report gestured at the Stardust’s strangeness: Here was a company that said it hoped to abide by global research norms, but was, by its very existence, flouting them. “It has generally been considered that private ownership of the means to manage the global atmosphere is not appropriate,” he wrote. “Yet the world is currently faced with a situation of de facto private finance funding [stratospheric aerosol injection] activities.”
Pasztor had initially hoped to publish his report and Stardust’s code of conduct together, he told me. But the company did not immediately establish a website, and eventually Pasztor simply released his report on LinkedIn. Stardust did not put up a website until earlier this year, during the reporting process for a longer feature about the company by the MIT-affiliated science magazine Undark. That website now features Pasztor’s report and a set of “principles,” though not the code of conduct Pasztor envisioned. They are “dragging their feet on that,” he said.
As news of the company trickled out, Stardust’s leaders grew more confident in their methods. In September 2024, Yedvab presented on Stardust’s approach to stratospheric researchers at the National Oceanic and Atmospheric Administration’s chemical sciences laboratory in Boulder, Colorado. The lab’s director, David Fahey, downplayed the importance of the talk. “There’s a stratospheric community in the world and we know all the long-term members. We’re an open shop,” he said. “We’ll talk to anyone who comes.” Stardust is the only company of its size and seriousness that has shown up, he said.
Stardust is the only company of its size and seriousness working on geoengineering, period, he added. “Stardust really stands out for the investment that they’re trying to make into how you might achieve climate intervention,” he said. “They’re realizing there’s a number of questions the world will need answered if we are going to put the scale of material in the stratosphere that they think we may need to.” (At least one other U.S. company, Make Sunsets, has claimed to release sulfates in the atmosphere and has even sold “cooling credits” to fund its work. But it has raised a fraction of Stardust’s capital, and its unsanctioned outdoor experiments set off such a backlash that Mexico banned all solar geoengineering experiments in response.)
Pasztor continued to work with Stardust throughout this year despite the company’s foot-dragging. He left this summer when he felt like he was becoming a spokesperson for a business that he merely advised. Stardust has more recently worked with Matthew Waxman, a Columbia law professor, on governance issues.
Today, Stardust employs a roughly 25-person team that includes physicists, chemists, mechanical engineers, material engineers, and climate experts. Many of them are drawn from Yedvab and Spector’s previous work on Israeli R&D projects.
The company is getting closer to its goals. Yedvab told me that it has developed a proprietary particle that meets its safety and reflectivity requirements. Stardust is now seeking a patent for the material, and it will not disclose the chemical makeup until it receives intellectual property protection. The company claims to be working with a handful of academics around the world on peer-reviewed studies about the particle and broader system, although it declined to provide a list of these researchers on the record.
As Yedvab sees it, the system itself is the true innovation. Stardust has engineered every part of its approach to work in conjunction with every other part — a type of systems thinking that Yedvab and Spector presumably brought from their previous career in government R&D.
Spector described one representative problem: Tiny particles tend to attract each other and clump together when floating in the air, which would decrease the amount of time they spend in the atmosphere, he said. Stardust has built custom machinery to “disagglomerate” the particles, and it has made sure that this dispersion technology is small and light enough to sit on an aircraft flying at or near the stratosphere. (The stratosphere begins at about 26,000 feet over the poles, but 52,000 feet above the equator.)
This integrated approach is part of why Stardust believes it is much further along than any other research effort. “Whatever group that would try to do this, you would need all those types of [people] working together, because otherwise you might have the best chemist, or make the best particle, but it would not fly,” Spector said.
With the new funding, the company believes that its technology could be ready to deploy as soon as the end of this decade. By then, the company hopes to have a particle fabrication facility, a mid-size fleet of aircraft (perhaps a fraction of the size of FedEx’s), and an array of monitoring technology and software ready to deploy.
Even then, its needs would be modest. That infrastructure — and roughly 2 million tons of the unspecified particle — would be all that was required to stop the climate from warming further, Spector said. Each additional million tons a year would reduce Earth’s temperature about half of a degree.
Yet having the technology does not mean that Stardust will deploy it, Yedvab said. The company maintains that it won’t move forward until governments invite it to. “We will only participate in deployment which will be done under adequate governance led by governments,” Yedvab told me. “When you're dealing with such an issue, you should have very clear guiding principles … There are certain ground rules that — I would say in the lack of regulation and governance — we impose upon ourselves.”
He said the company has spoken to American policy makers “on both sides of the aisle” to encourage near-term regulation of the technology. “Policymakers and regulators should get into this game now, because in our view, it's only a matter of time until someone will say, Okay, I'm going and trying to do it,” Yedvab said. “And this could be very dangerous.”
There is a small and active community of academics, scientists, and experts who have been thinking and studying geoengineering for a long time. Stardust is not what almost any of them would have wished a solar geoengineering company to look like.
Researchers had assumed that the first workable SRM system would come from a government, emerging at the end of a long and deliberative public research process. Stardust, meanwhile, is a for-profit company run by Israeli ex-nuclear physicists that spent years in stealth mode, is seeking patent protections for its proprietary particle, and eventually hopes — with the help of the world’s governments — to disperse that particle through the atmosphere indefinitely.
For these reasons, even experts who in other contexts support aggressive research into deploying SRM are quite critical of Stardust.
“The people involved seem like really serious, thoughtful people,” David Keith, a professor and the founding faculty director of the Climate Systems Engineering Initiative at the University of Chicago, told me. “I think their claims about making an inert particle — and their implicit assumption that you can make a particle that is better than sulfates” are “almost certain to be wrong.”
Keith, who is on the scientific advisory board of Reflective, a San Francisco-based nonprofit that aims to accelerate SRM research and technology development, has frank doubts about Stardust’s scientific rationale. Sulfates are almost certainly a better choice than whatever Stardust has cooked up, he said, because we have already spent decades studying how sulfates act. “There’s no such particle that’s inert in the stratosphere,” he told me. “Now maybe they’ve invented something they’ll get a Nobel Prize for that violates that — but I don’t think so.”
He also rejects the premise that for-profit companies should work on SRM. Keith, to be clear, does not hate capitalism: In 2009, he founded the company Carbon Engineering, which developed carbon capture technology before the oil giant Occidental Petroleum bought it for $1.1 billion in 2023. But he has argued since 2018 that while carbon capture is properly the domain of for-profit firms, solar engineering research should never be commercialized.
“Companies always, by definition, have to sell their product,” he told me. “It’s just axiomatic that people tend to overstate the benefits and undersell the risk.” Capitalistic firms excel at driving down the cost of new technologies and producing them at scale, he said. But “for stratospheric aerosol injection, we don’t need it to be cheaper — it’s already cheap,” he continued. “We need better confidence and trust and better bounding of the unknown unknowns.”
Shuchi Talati, who founded and leads the Alliance for Just Deliberation on Solar Geoengineering, is also skeptical. She still believes that countries could find a way to do solar geoengineering for the public good, she told me, but it will almost certainly not look like Stardust. The company is in violation of virtually every norm that has driven the field so far: It is not open about its research or its particle, it is a for-profit company, and it is pursuing intellectual property protections for its technology.
“I think transparency is in every single set of SRM principles” developed since the technology was first conceived, she said. “They obviously have flouted that in their entirety.”
She doubted, too, that Stardust could actually develop a new and totally biosafe chemical, given the amount of mass that would have to be released in the stratosphere to counteract climate change. “Nothing is biosafe” when you disperse it at sufficient scale, she said. “Water in certain quantities is not biosafe.”
The context in which the company operates suggests some other concerns. Although SRM would likely make a poor weapon, at least on short time scales, it is a powerful and world-shaping technology nonetheless. In that way, it’s not so far from nuclear weapons. And while the world has found at least one way to govern that technology — the nonproliferation regime — Israel has bucked it. It is one of only four countries in the world to have never signed the Nuclear Nonproliferation Treaty. (The others are India, Pakistan, and South Sudan.) Three years ago, the UN voted 152 to 5 that Israel must give up its weapons and sign the treaty.
These concerns are not immaterial to Stardust, given Yedvab and Spector’s careers working as physicists for the government. In our interview, Yedvab stressed the company’s American connections. “We are a company registered in the U.S., working on a global problem,” he told me. “We come from Israel, we cannot hide it, and we do not want to hide it.” But the firm itself has “no ties with the Israeli government — not with respect to funding, not with respect to any other aspect of our work,” he said. “It’s the second chapter in our life,” Spector said.
Stardust may not be connected to the Israeli government, but some of its funders are. The venture capital firm AWZ, which participated in its $15 million seed round, touts its partnership with the Israeli Ministry of Defense’s directorate of defense R&D, and the fund’s strategic advisors include Tamir Pardo, the former director of the Israeli intelligence agency Mossad. “We have no connection to the Israeli government or defense establishment beyond standard regulatory or financial obligations applicable to any company operating in Israel,” a spokesperson for Stardust reiterated in a statement when I asked about the connection. “We are proud that AWZ, along with all of our investors, agrees with our mission and believes deeply in the need to address this crisis.”
One of Stardust’s stated principles is that deployment should be done under “established governance, guided by governments and authorized bodies.” But its documentation provides no detail about who those governments might be or how many governments amount to a quorum.
“The optimal case, in my view, is some kind of a multilateral coalition,” Yedvab said. “We definitely believe that the U.S. has a role there, and we expect and hope also the other governments will take part in building this governance structure.”
Speaking with Pasztor, I observed that the United States and Israel’s actions often deviate sharply from what the rest of the world might want or inscribe in law. What if they decided to conduct geoengineering themselves? “This gets into a pretty hairy geopolitical discussion, but it has to be had,” Pasztor told me. He had discussed similar issues with the company, he said, adding that “at just about every meeting he had” with the team, Stardust’s leaders hoped to “disassociate and distance themselves” from the current Israeli government. “Even when there were suggestions in my recommendations that the first step is to work through ‘your government’ — their thinking was, Okay, we will do it with the Americans,” he said.
He also discussed with the team the risks of the United States going it alone and pursuing stratospheric aerosol injection by itself. That would produce an enormous backlash, Pasztor warned, especially when the Trump administration “is doing everything contrary to what one should do” to fight climate change. “And then doing the U.S. and Israel together — given the current double geopolitical context — that would be even worse,” he said. (“Of course, they could get away with it,” he added. “Who can stop the U.S. from doing it?”)
And that hints at perhaps the greatest risk of Stardust’s existence: that it prevents progress on climate change simply because it will discourage countries from cutting their fossil fuel use. Solar geoengineering’s biggest risk has long seemed to be this moral hazard — that as soon as you can dampen the atmospheric effects of climate change, countries will stop caring about greenhouse gas emissions. It’s certainly something you can imagine the Trump administration doing, I posed to Yedvab.
Yedvab acknowledged that it is a “valid argument.” But the world is so off-track in meeting its goals, he said, that it needs to prepare a Plan B. He asked me to imagine two different scenarios, one where the world diligently develops the technology and governance needed to deploy solar geoengineering over the next 10 years, and another where it wakes up in a decade and decides to crash toward solar geoengineering. “Now think which scenario you prefer,” he said.
Perhaps Stardust will not achieve its goals. Its proprietary particle may not work, or it could prove less effective than sulfates. The company claims that it will disclose its particle once it receives its patent — which could happen as soon as next year, Yedvab and Spector said — and perhaps that process will reveal some defect or other factor that means it is not truly biosafe. The UN may also try to place a blanket ban on geoengineering research, as some groups hope.
Yet Stardust’s mere existence — and the “free driver” problem articulated by Barrett nearly two decades ago — suggests that it will not be the last to try to develop geoengineering technology. There is a great deal of interest in SRM in San Francisco’s technology circles; Pastzor told me that he saw Reflective as “not really different” from Stardust outside of its nonprofit status. “They’re getting all the money from similar types of funders,” he said. “There is stuff happening and we need to deal with it.”
For those who have fretted about climate change, the continued development of SRM technology poses something of a “put up or shut up” moment. One of the ideas embedded in the concept of “climate change” is that humanity has touched everywhere on Earth, that nowhere is safe from human influence. But subsequent environmental science has clarified that, in fact, the Earth has not been free of human influence for millennia. Definitely not since 1492, when the flora and fauna of the Americas encountered those of Afro-Eurasia for the first time — and probably not since human hunters wiped out the Ice Age’s great mammal species roughly 10,000 years ago. The world has over and over again been remade by human hands.
Stardust may not play the Prometheus here and bring this particular capability into humanity’s hands. But I have never been so certain that someone will try in our lifetimes. We find ourselves, once again, in the middle of things.
Much of California’s biggest county is now off limits to energy storage.
Residents of a tiny unincorporated community outside of Los Angeles have trounced a giant battery project in court — and in the process seem to have blocked energy storage projects in more than half of L.A. County, the biggest county in California.
A band of frustrated homeowners and businesses have for years aggressively fought a Hecate battery storage project proposed in Acton, California, a rural unincorporated community of about 7,000 residents, miles east of the L.A. metro area. As I wrote in my first feature for The Fight over a year ago, this effort was largely motivated by concerns about Acton as a high wildfire risk area. Residents worried that in the event of a large fire, a major battery installation would make an already difficult emergency response situation more dangerous. Acton leaders expressly opposed the project in deliberations before L.A. County planning officials, arguing that BESS facilities in general were not allowed under the existing zoning code in unincorporated areas.
On the other side, county officials maintained that the code was silent on battery storage as such, but said that in their view, these projects were comparable to distribution infrastructure from a land use perspective, and therefore would be allowable under the code.
Last week, the residents of Acton won, getting the courts to toss out the county’s 2021 memorandum allowing battery storage facilities in unincorporated areas – which make up more than 65% of L.A. County.
Judge Curtis Kin wrote in his October 14 ruling that “such expansive use of the interpretation runs contrary to the Zoning Code itself,” and that the “exclusion” of permission for battery storage in the code means it isn’t allowed, plain and simple.
“Consequently, respondents and real parties’ reliance on the existence of other interpretive memos and guidance by the [Planning] Director is beside the point,” Kin stated. “There is no dispute the Director has the authority to issue memos and interpretations for Zoning code provisions subject to interpretation, but, as discussed above, such authority cannot be used in such a way as to violate the provisions of the Zoning Code.”
The court also declared the Hecate project approval void and ordered the company to seek permits under the California Environmental Quality Act if it still wants to build. This will halt the project’s development for the foreseeable future. Alene Taber, the attorney representing Acton residents, told me she has received no indication from Hecate’s legal team about whether they will appeal the ruling.
Hecate declined to comment on the outcome.
Taber’s perspective is unique as a self-described “rural rights” attorney who largely represents unincorporated communities with various legal disputes. She told me this ruling demonstrates a serious risk regulators face in moving too fast for a host community, especially given rising opposition to battery storage in California. Since the Moss Landing fire, opposition to storage projects has escalated rapidly across the state – despite profound tech differences between more modern designs proposed today and the antiquated system that burned up in that incident.
I asked Taber if she thought California enacting a new law last week to beef up battery fire safety oversight could stem the tide of concerns about battery storage. In response, she railed against a separate statute giving energy companies – including battery developers – the ability to work around town ordinances and moratoria targeting their industry.
“Even though the county didn’t consider the community input — which it should’ve — the county process at least still allowed for communities to appeal the project. And they’re also at least supposed to consider what the local zoning code said,” Taber told me. “Local communities are now sidelined all together. They’re saying they don’t care what the concerns are. Where’s the consideration for how these projects are now being sited in high fire zones?”
I was unable to reach Los Angeles County officials before press time for The Fight, but it’s worth noting that, amid the battle over Hecate’s approval, L.A. County planning officials began preparing to update their renewable energy ordinance to include battery storage development regulation – an indication they may need new methods to site and build more battery storage. There’s no timeline for when those changes will take place.
And more of the week’s top news about renewable energy conflicts.
1. Benton County, Washington – A state permitting board has overridden Governor Bob Ferguson to limit the size of what would’ve been Washington’s largest wind project over concerns about hawks.
2. Adams County, Colorado – This is a new one: Solar project opponents here are making calls to residents impersonating the developer to collect payments.
3. Lander County, Nevada – Trump’s move to kill the Esmeralda 7 solar mega-project has prompted incredible backlash in Congress, as almost all of Nevada’s congressional delegation claims that not a single renewables project in the U.S. has gotten a federal permit since July.