UK scientists are set to conduct outdoor geoengineering experiments as part of a £50 million government-funded programme, the Advanced Research and Invention Agency (Aria) has announced. The small-scale trials aim to provide critical data on technologies that could temporarily slow climate change by blocking sunlight.
Geoengineering remains highly controversial, with previous outdoor plans cancelled due to opposition. Most proposals involve reflecting sunlight away from Earth, such as releasing reflective particles into the atmosphere or brightening clouds with seawater sprays. Supporters argue that research is vital given rising global temperatures and insufficient emissions cuts.
However, critics warn of unintended consequences, including disrupted rainfall patterns and reduced motivation to cut fossil fuel use. Professor Mark Symes, leading the Aria programme, said the threat of climate tipping points—such as collapsing ocean currents or ice sheets—necessitates real-world data. “Modelling and indoor studies can only tell us so much,” he noted.
The programme will publish environmental impact assessments and consult local communities before any experiments. No toxic substances will be released, Symes added. Separately, the UK’s National Environment Research Council announced a £10 million geoengineering research project, relying on modelling and natural analogues rather than outdoor tests.
Global funding for geoengineering remains modest, but the UK could become the leading funder as US research faces cuts under President Trump. Dr Pete Irvine from the University of Chicago stressed that geoengineering is not a substitute for emission reductions. Professor Jim Haywood of the University of Exeter said scaling up such projects could be feasible within a decade, adding that “recent global temperatures have been a real wake-up call.”
