A team of UK scientists is exploring whether spraying fine salt water into the sky could brighten clouds and reflect more sunlight back into space, potentially helping to cool parts of the planet. The technique, known as marine cloud brightening, is being tested at the University of Manchester as part of the REFLECT project, funded by the UK's Advanced Research and Invention Agency (ARIA).
Led by Professor Hugh Coe, the researchers are using a three-storey stainless-steel cloud chamber to study how seawater mists interact with clouds. The goal is to determine whether the approach can effectively reflect sunlight and mitigate extreme heat, such as that threatening the Great Barrier Reef. Potential real-world trials could begin as early as 2028, pending safety and community approvals.
ARIA has allocated £57m to 22 geoengineering schemes under its Exploring Climate Cooling programme. The initiative aims to provide objective evidence on whether such techniques are safe, effective, and governable. However, researchers stress that decarbonisation remains the only sustainable solution to the climate crisis.
Mark Symes, ARIA's programme director, said: “Decarbonisation is the only sustainable route out of the climate crisis. However, decarbonisation is not happening quickly enough to protect many parts of the world from the worst effects of global heating.” He added that the programme seeks to fill the gap in objective data needed for informed decisions.
The REFLECT team is currently developing bespoke sprayers and computer models to optimise droplet sizes, while engaging with coastal communities that could host future tests. No outdoor experiments are planned before 2028, and any trials would be small-scale, short-term, and closely monitored, using only seawater to mimic natural sea spray.
ARIA, inspired by the US agency DARPA, was established in 2022 with cross-party support. It has an initial budget of £800m, rising to £400m per year by 2030. The REFLECT project aims to build a transparent framework for evaluating whether marine cloud brightening could play a role in managing extreme heat as global temperatures rise.
