The Israeli-U.S. startup Stardust Solutions announced last week that it raised $60 million in venture capital in its latest funding round – the largest venture investment to date for a for-profit company developing solar geoengineering technology, particularly injection of reflective particles into the stratosphere.
Stardust’s team includes nuclear scientists who previously worked for the Israeli government at the Negev Nuclear Research Center and the Israeli Atomic Energy Commission. The company seeks to patent its reflective particles, and pursue government contracts to manufacture and deploy them. The rationale advanced appears to be inspired by a solutionist reading of the U.S. National Academy of Sciences report, portraying solar geoengineering as a relatively easy way to “stop global warming”. Stardust has raised seed funding from SolarEdge and Awz Ventures, a Canadian-Israeli venture capital firm with reported links to Israel’s Ministry of Defence; and most recently from several Silicon Valley firms as well as former Facebook executive Matt Cohler who has also previously supported other outreach initiatives such as the Degrees Initiative and SilverLining. Stardust’s invitation of Janos Pasztor – a former UN diplomat with long experience in solar geoengineering debates – to advise them on the governance implications of their work has not exercised any brakes.
A few days after the Stardust announcement, Elon Musk tweeted in support of what appeared to be geoengineering via space-mirrors, which even advocates for other solar geoengineering variants find implausible. Musk’s mercurial nature makes it difficult to gauge sustained interest. However, his agendas and ventures are a concerning context – including his role in cutting US government services, takeover of a leading online platform, and aspirations towards space colonization as an ostensible failsafe for human civilization. The tweet also connects solar geoengineering to frontier technology fields – from the space economy to artificial intelligence – where Musk has interest and investment.
Source: Screenshot from X, [@elonmusk], 3 November 2025.
In short: longstanding private sector interests in solar geoengineering have irrevocably surfaced – with for-profit motives, varying ties to frontier technology and defence industries, simplified and solutionist interpretations of technical assessments, and appeals to being transformative for climate action.
Solar geoengineering advocates have scrambled to respond. This repeats history from when Make Sunsets, a shoestring start-up selling spurious ‘cooling credits’ from launching weather balloons filled with sulphur dioxide, made the news in 2024. Despite the profound difference in capacity and funding between Make Sunsets, Stardust and Musk, the response of solar geoengineering advocates has remained the same. They begin by distancing themselves, by describing for-profit companies as rogue, isolated, or misguided. They portray commercial motives as irresponsible and short-sighted, positioning themselves as the guardians of ‘responsible’ solar geoengineering research. While implying a claim to representing science in the global public interest – by referencing principles of transparency and inclusion, or appealing to helping the world’s most vulnerable – they continue to call for more attention, more funding, more research, and more field-tests of solar geoengineering.
But why are advocates surprised?
A plea for political reality
Stardust, Make Sunsets, and Elon Musk’s signalling are not rogue exceptions. They are, as a group of researchers critical of solar geoengineering recently put it, “a predictable consequence of neoliberal climate politics dominated by market-driven policies, and the prominent role played by technology billionaires and Silicon Valley interests in advancing solar geoengineering research”.
As such, advocacy of ‘responsible’ planetary-scale solar geoengineering research remains divorced from political reality, no matter how many well-intentioned principles of good governance are rolled out. Despite advocates’ best hopes, solar geoengineering is not going to unfold through transparent public funding for mission-driven technical assessment, with perverse agendas held at bay by codes of conduct and (supportive) global public engagement, and geopolitical decision-making taking its cue from idealized modelling scenarios that presume centuries of stable multilateral cooperation around sunshade maintenance.
Instead, for-profit R&D in solar geoengineering reflects the political reality that high-stakes planet-altering technologies will become implicated in a multipolar world with troubling trends towards authoritarianism and populism, permissive regulations for frontier technologies, and insufficient decarbonization. Furthermore, any large-scale testing or deployment of solar geoengineering is inevitably a national security issue. Scholars have been warning for years that solar geoengineering has to be considered through the lens of securitization, diplomatic gamesmanship, and hybrid warfare. Yet despite these warnings, the main trunk of advocacy – particularly for stratospheric aerosol injection – has been driven by idealized modelling for most of the past 20 years.
In such a context, any push to introduce a climate lever described by solar geoengineering advocates as “cheap, fast, and imperfect” at, for example, the UNFCCC would likely disrupt longstanding negotiation agendas and factions on everything from emissions reduction targets to loss and damage, as exposed by clear tensions at the UN Environmental Assembly in 2019. Yet, efforts to parachute and promote solar geoengineering within UN bodies also persist.
The North-South perspective is also crucial here. There is little doubt that oversight over solar geoengineering will never be driven by – or even adequately include – the governments or citizens of the most vulnerable states. African states themselves recognize this reality and have called three times for the non-use of solar geoengineering – at the African Ministerial Conference on the Environment (AMCEN) in 2023, at the UN Environmental Assembly in 2024 and again during the 2025 AMCEN. These calls have recently been reiterated by Vanuatu and Fiji. Yet, advocates continue to rely on the moral ammunition of relieving climate harms for the most vulnerable.
Conspiracy theories already shape public understanding of solar geoengineering. Advocates lament the post-truth era of political discourse, particularly in the US – but seemingly mostly because this has led to proposals for banning solar geoengineering across multiple US states. Yet, there are far more concerning implications of misinformation. If Americans are already so thoroughly polarized or misinformed about solar geoengineering research in sub-national contexts in their own country, there will be fierce reactions to a federal program – or worse still, a program by a foreign power.
Politically aware, not anti-science
For decades, many critics of solar geoengineering have been arguing that politics matter. Solar geoengineering research and development cannot be separated from political decision-making and commercial intent. There are profound concerns regarding geopolitics, power, inequality, and justice. Despite this, optimistic conceptions of public-good oriented research and deployment are being marketed to policy-makers, implying long-term controllability and near-term necessity. Yet, the development of future solar geoengineering – regardless of the intentions of scientists – will be appropriated by corporate and political actors.
In this context, one also has to ask: whose research do these for-profit enterprises rely on? Make Sunsets has publicized on their website the research of prominent solar geoengineering advocates as providing the foundational research underpinning their scheme. In a recent critique of Stardust as “bad for science and public trust”, two solar geoengineering advocates conclude that “ultimately, we’re just two researchers” who cannot make investors or startups do anything differently. This highlights that research never lands in a political vacuum, even as it hammers home a core point that critics have long emphasized: that no matter how well-intentioned, scientists will not decide about the development and use of these high-stakes technologies.
And yet, if a scholar, practitioner, or activist critical of solar geoengineering uses these reasons to advance a judgement that solar geoengineering should not be considered as an option for addressing climate change, they are said to promote ignorance or restrict freedom of research.
The academic initiative calling for an International Non-Use Agreement on Solar Geoengineering is also accused of this. But it is not a matter of being anti-science – almost 600 academics, including many IPCC authors, support the non-use initiative. Rather, it is a reflection that scholars of every discipline and from across the world are aware of the political realities that will shape solar geoengineering, borne out by their research and experience in the governance of global issues.
As long as advocates ignore the politics of planetary solar geoengineering, they will continue to be surprised when events like Stardust unfold.
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This document can be cited as: SGNUA (2025). Solar Geoengineering for Profit. Initiative calling for an International Non-Use Agreement on Solar Geoengineering. Available at: https://www.solargeoeng.org/solar-geoengineering-for-profit/
This blog post is based on discussions within the initiative for an International Non-Use Agreement on Solar Geoengineering and has been written with contributions from Heleen Bruggink, Sean Low, Aarti Gupta, Frank Biermann, Kevin Surprise, Florian Rabitz, Rakhyun E. Kim, Mike Hulme, Peter Newell, Raymond Pierrehumbert, Louis Kotzé, Margaretha Wewerinke-Singh and Jennie C. Stephens. Views expressed here do not necessarily represent all signatories of the open letter calling for a non-use agreement.