In a concerning development for global climate efforts, once-fringe ideas about artificially cooling the planet by blocking sunlight are attracting billions in funding and powerful backers. As climate action continues to stall and extreme heat accelerates worldwide, tech billionaires and startups are taking matters into their own hands with solar radiation modification technologies that could have irreversible consequences.
The Rising Tide of Solar Geoengineering
A record-breaking funding round for solar geoengineering companies signals that what was once considered scientific fantasy is becoming serious business. Recent data reveals that between 2007 and 2024, only $17.6 million in funding went to commercial solar geoengineers, representing just a fraction of the sector's total $185.7 million funding. However, this year alone, a single US-Israeli startup called Stardust has raised $60 million from investors, according to PitchBook data.
The substantial funding was led by tech billionaire Chris Sacca's venture firm Lowercarbon Capital and joined by other wealthy backers including Italy's Agnelli family and Matt Cohler, an ex-Facebook executive. This massive investment surge demonstrates growing confidence in technologies that aim to mask some effects of climate change by blocking sunlight.
Scientific Concerns and Rogue Actors
The rapid commercialization of solar geoengineering is raising alarm bells among climate researchers. In a recent poll of climate experts, two-thirds predicted an attempt to deploy large-scale solar radiation modification by 2100, with only 9% confident that no such attempt would occur. Even more concerning, more than half of these researchers believe deployment will be driven by a "rogue actor" such as a private company, billionaire, or nation state acting unilaterally.
Solar geoengineering can only serve as a temporary painkiller, not a cure, for the climate crisis. The technology comes with numerous poorly understood potential side effects that could have devastating consequences. Methods like stratospheric aerosol injection (SAI), which involves spraying reflective materials such as sulfur dioxide into the stratosphere, could cause acid rain, trigger asthma attacks, and damage the ozone layer.
Elon Musk recently added to the conversation by posting on X that "a large solar-powered AI satellite constellation would be able to prevent global warming by making tiny adjustments in how much solar energy reached Earth," potentially referring to his own Starlink satellite network.
The Corporate Rush and Governance Gaps
Stardust, the startup that recently secured $60 million, claims to be pursuing SAI with a better particle than sulfates, which come with serious downsides. The company is seeking a patent for what it believes could be the perfect particle—completely safe, robust, non-reactive, and trackable. However, scientists remain skeptical about these claims.
David Keith, professor of geophysical sciences at the University of Chicago, and Daniele Visioni, head of data for Reflective, have stated that claims of an inert stratospheric particle are "nonsense," noting that even diamonds would alter chemistry 50 kilometers above Earth's surface.
The average lifespan of a US S&P 500 company is just 15 years, down from 67 eight decades ago. This creates serious concerns about the long-term stability required for solar geoengineering technologies, which would need to remain absolutely stable for potentially hundreds of years to be effective and avoid catastrophic termination shock.
The current regulatory landscape is alarmingly inadequate. Some US states have banned solar geoengineering based on chemtrail conspiracies, while Mexico barred experiments after another startup, Make Sunsets, began releasing sulfur-filled weather balloons to generate 'Cooling Credits' for sale. The UN Convention on Biological Diversity has established a moratorium on geoengineering, but the US hasn't ratified the treaty, and it's not legally binding.
As the European Union noted in a scientific opinion issued in December, global governance is urgently needed for solar geoengineering, but "no such framework exists, and it's not clear how one could be created." This regulatory vacuum, combined with massive private investment, creates a perfect storm for potentially reckless deployment of technologies that could alter our planet's climate systems permanently.
