Foundation calls for international rules on solar radiation management as global investments rise

As global funding for solar radiation management (SRM) has increased more than tenfold in the past six years, the international community should agree on rules to prohibit the development and use of these technologies, said the German Heinrich-Böll-Foundation – a think tank closely affiliated with the Green Party. 

“These are high-risk technologies with potentially catastrophic global consequences,” said climate policy officer Linda Schneider. She added that solar radiation management efforts deliberately interfere with the Earth's climate system, but that the impact on weather patterns, ecosystems and societies is difficult to predict. Given the current geopolitical reality, internationally coordinated use of SRM “is extremely unlikely” and individual governments could attempt to use such technologies at the expense of others, Schneider said. “That is why we now need clear international rules that rule out further development and possible use of these technologies.”

An analysis by the Böll Foundation said funding for solar geoengineering has increased significantly, but total spending was difficult to estimate, because much of the funding for solar geoengineering came from philanthropic organisations “with minimal regulation on the disclosure of their funding.” More than 128 million US dollars was spent on solar geoengineering activity from 2020 to 2025, with the majority coming from the US and UK, said the report. 

Solar radiation management (or modification) is a form of geoengineering. It aims to reduce incoming solar radiation to help cool the atmosphere at ground level, for example by releasing aerosols into the upper atmosphere. Geoengineering refers to the application of large-scale technical measures that directly intervene in the climate system to limit human-made global heating – but do not actually reduce emissions. A 2024 report by the German Environment Agency (UBA) outlined the risks of SRM for water resources, food security, and the environment. “An unpredictable new global climate would emerge, accompanied by significant regional impacts,” the agency said. 

Researchers and companies are increasingly looking into “futuristic” technologies to address the climate crisis – such as geoengineering, large-scale carbon removal, or nuclear fusion. Israeli-US startup Stardust Solutions last year announced the largest-ever fundraising round for any company that aims to cool the Earth by spraying particles into the atmosphere. The German government under chancellor Friedrich Merz meanwhile reiterated its stance against SRM as a way to combat the effects of climate change.