Preface

The Heinrich Böll Foundation has monitored solar geoengineering developments since 2010. This report highlights a sharp rise in funding for research, technology development, and advocacy, which has moved these high-risk technologies into mainstream climate policy discussions. The study aims to identify the economic and political interests shaping the field, raising concerns that rapid private-sector growth may sideline democratic deliberation.

Executive summary

Between 2020 and 2025, total known funding for solar geoengineering increased more than tenfold, rising from under $6 million in 2020 to over $60 million in 2025. Over this period, more than $128 million in constant dollars was spent on geoengineering activities, and the number of known payments grew from 16 to 100. Philanthropic foundations and government agencies are the primary sources of support. Real spending is estimated to be three to four times higher due to minimal regulation on disclosure.

Introduction

Solar geoengineering is described as a “techno-fix” that attempts to rectify ecological problems through technological innovation rather than addressing root social causes. High-profile tech billionaires, including Bill Gates, Chris Sacca, and Sam Altman, have advocated for the technology as an “insurance policy” or “Band-Aid” to buy time. Critics argue this approach serves the interests of industries requiring high energy consumption, such as artificial intelligence, by delaying necessary decarbonisation.

Critiques of solar geoengineering

The impacts of deployment remain largely unknown and could affect earth systems in unexpected ways. Key concerns include the risk of “termination shock”, where a sudden cessation of aerosol injection would cause rapid and catastrophic warming. Additionally, the prospect of a technological remedy may reduce the urgency for emissions reductions, an effect known as mitigation deterrence. Every decision regarding deployment represents a potential accumulation of power in the hands of those controlling the technology.

Methodology

Researchers constructed a database of 206 organisations, including 43 funders and 166 recipients, using news media, business databases, and public disclosures. The study identified 78 research grants for specific projects and 107 non-grant payments. All monetary values were unified by inflation-adjusting currencies to December 2024 values and converting them to US dollars to allow for consistent comparison between international funding sources.

Solar geoengineering funding

Funding is heavily concentrated in the Global North, with over 80% of funding organisations based in the US or UK. Regional analysis shows that 96% of total known funding flows ($123,872,000) are directed toward the US or Europe. While philanthropic foundations dominated the field for several years, a significant infusion of government funding occurred in 2025, particularly from the UK-based Advanced Research and Invention Agency (ARIA).

Known funding flows

Only 13 of the 43 known funders reported the monetary value of their contributions. The vast majority of organisations do not disclose specific payment values, meaning actual funding is likely much higher than reported. Philanthropic foundations such as the Quadrature Climate Foundation, Open Philanthropy, and the Simons Foundation have steadily supported advocacy and research, with a dramatic peak in activity recorded in 2024 and 2025.

Direct research grants

ARIA is a major contributor, granting over $56 million across 22 research projects in 2025, including five projects involving outdoor testing. The US National Science Foundation (NSF) contributed $4.6 million for seven research grants, while the National Oceanic and Atmospheric Administration (NOAA) provided nearly $4 million. Most research funding is directed toward modelling (64.1%), followed by laboratory experiments (16.7%) and governance research (7.7%).

General funding

Thirty-six funders provided general support that could not be tied to specific research grants. The Quadrature Climate Foundation provided over $35.8 million in general support, including $12.1 million to the NGO SilverLining. Other notable general funders include the LAD Climate Fund and the Pritzker Innovation Fund. SilverLining acts as both a recipient and a funder, distributing over $7 million in grants and directing a further $15 million toward solar geoengineering activities.

Ultra-rich individuals behind funder organisations

Of the 33 funders that are either philanthropic foundations or investment firms, more than half derive their capital from technology-related ventures. Key individuals include Bill Gates (Microsoft), Dustin Moskovitz (Meta), and George Soros (Open Society Foundations). Many of these funders maintain a techno-optimist outlook, betting on speculative technologies like carbon capture and advanced AI to avoid restructuring the existing social order.

Solar geoengineering startups

Two startups, Make Sunsets and Stardust Solutions, have emerged to monetise solar radiation management. Make Sunsets sells “cooling credits” for injecting sulphur into the stratosphere, claiming that one gram offsets one tonne of CO2. Stardust Solutions, an Israeli firm, received at least $15 million in funding from energy and venture capital firms to research and eventually deploy stratospheric aerosol injection technologies.

Summary of findings and synthesis

The data reveals four primary patterns: an uneven geography favouring North America and Europe; a focus on research, with nine-tenths of recipients being universities or governmental bodies; exclusive private support for awareness and advocacy groups; and the high-tech sector as a major source of capital. This persistently biased distribution runs contrary to the expressed goal of including Global South interests in geoengineering governance.

Conclusion: Some final considerations

Solar geoengineering is not a technological panacea and risks disrupting an already turbulent climate system. The report calls on funders to redirect resources toward proven, equitable climate solutions that address root causes. It concludes that those most responsible for historic emissions are those most aggressively pursuing these technologies, while nations in the Global South, which face the highest risks, remain largely opposed to their use.