Campaigners working to limit the use of controversial sun-dimming technology have praised the Europe’s foreign ministers for warning of the risks such technology poses, but opinions remain split over whether it merits more research, with the European Union keeping its position open for now.
At a joint council meeting in Luxembourg, ministers representing the EU’s 27 member states signed off on a statement agreeing for the first time that they were “concerned that large-scale climate interventions, in particular solar radiation modification (SRM), pose significant risks for the climate, the environment, security and geopolitics”.
Their statement, issued in late April, called for a moratorium on deployment of SRM technologies, as well as “the full application of the precautionary principle to geoengineering” and for the EU to engage in international talks on international governance arrangements, including those related to research.
SRM refers to any deliberate attempt to reduce the amount of heat which reaches the Earth from the sun. This could be carried out by artificially brightening clouds or injecting aerosols into the atmosphere, which could reduce or reverse global warming but risk severe and unpredictable side-effects.
The risks of carrying out SRM are widely acknowledged but climate campaigners and scientists remain divided on to what extent and how its effects should be researched, with some arguing that such work normalises it and encourages its deployment.
Experts on both sides of the debate welcomed the EU’s statement but made contrasting calls on what should happen next. A more pro-research group said the EU should encourage responsible research into SRM’s effects while more anti-research campaigners said the EU should prevent research that could lead to SRM’s deployment and agree not to use it.
Responsible research
Giulia Neri, the interim director of climate interventions at the Brussels-based think-tank Centre for Future Generations (CFG), which supports research into SRM, told Climate Home News that the EU’s statement sends “an important and timely signal on the need for rules governing SRM”.
She added that the fact it was issued by foreign – not climate – ministers shows “a growing recognition that SRM is a geopolitically relevant technology and not merely a climate-related issue”.
Her colleague, CFG adviser on climate interventions, Matthias Honneger added that the EU nations’ ministers in charge of research “might also consider how responsible public research under European oversight can help maintain Europe’s influence”.
This is especially important, Honneger said, as “private and global actors increasingly dominate what we know about this technology and its risks and benefits”.
A well-funded US-Israeli company Stardust claims to be developing the ability to carry out SRM and is seeking customers – including the US government – to pay for them to do so.
Impossible to test
Mary Chuch, who campaigns against geoengineering for the Center for International Environmental Law, also welcomed the foreign ministers’ statement.
She said it was right to emphasise “the risks of highly speculative geoengineering technologies, centre the precautionary principle and reinforce the longstanding moratorium under the Convention on Biological Diversity”.
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But, rather than calling for more research, she and political scientist Frank Biermann called for the EU to join governments in Africa and the Pacific in calling for an international non-use agreement on solar geoengineering.
“As an immediate first step, the European Union must prevent research that could lead to the development and use of solar geoengineering technologies,” Biermann said.
Church said that solar geoengineering is “inherently unpredictable” and that it was “impossible to fully test for intended and unintended impacts without prolonged large-scale implementation”.
De facto moratorium
The council’s conclusion did not weigh in on the research debate, only resolving to engage in talks on the governance of research.
But European Commissioner for Startups, Research and Innovation Ekaterina Zaharieva said in 2024 that research should continue although it should be “rigorous and ethical, and it must take full account of the possible range of direct and indirect effects”.
Also in 2024, the Swiss government attempted to get countries at the United Nations Environment Assembly (UNEA) to set up an expert group on SRM. But this failed due to opposition from the African Group, Colombia, Mexico and others, and Switzerland did not try again at the last UNEA in December 2025.
SRM is currently legal in most nations. But there has been a de facto global moratorium in place on geoengineering – which includes SRM – since 2010, when it was agreed by governments under the Convention on Biological Diversity, with exceptions for small-scale scientific research studies.
