Geoengineering is taking center stage in a new UK government initiative that funds real-world experiments across the globe—from the Arctic to the Great Barrier Reef—to explore sun-reflecting technologies that may temporarily cool the planet. Spearheaded by the Advanced Research and Invention Agency (Aria), the £56.8 million program aims to gather “critical missing scientific data” as the Earth approaches dangerous climate tipping points. The focus is on small-scale, rigorously assessed trials that could inform safe deployment if needed in the future.
Key techniques under study include stratospheric aerosol injection (releasing non-toxic particles to reflect sunlight), marine cloud brightening (spraying seawater to enhance cloud reflectivity), and sea ice restoration (pumping seawater to freeze and thicken ice). One such project involves launching weather balloons carrying mineral dust into the stratosphere above the US or UK to observe how particles behave in high-altitude conditions. Another experiment will enhance marine cloud brightness using seawater sprays and electrical charges from drones, potentially extending up to 100 square kilometers over the Great Barrier Reef. A similar approach will be tested off the UK coast.
In the Arctic, scientists will pump water onto sea ice during winter in Canada to encourage refreezing. This method could help preserve ice into the summer months, maintaining the reflective surface that deflects solar radiation and slows warming.
Despite the promise, geoengineering remains highly controversial. Critics argue that it distracts from urgent emissions reductions and poses significant risks of unintended climate consequences, such as altered precipitation patterns. Some scientists and environmental groups, including the Center for International Environmental Law and experts like Oxford’s Prof Raymond Pierrehumbert, warn that these experiments could normalize dangerous interventions and create momentum toward full-scale deployment without proper governance.
In response, Aria emphasizes transparency, local community engagement, and environmental assessments before conducting outdoor trials. An independent oversight committee, chaired by climate scientist Prof Piers Forster and featuring international members, is built into the process to ensure accountability.
Complementing the field trials, seven modeling teams will simulate the potential impacts of geoengineering on global climates and ecosystems, with particular focus on the Global South, where 85% of the world’s population resides. Five additional teams will delve into the ethical, legal, and governance challenges, exploring questions around consent, responsibility, and equitable access.
The initiative also explores futuristic ideas such as space-based solar reflectors and utilizes drones to study volcanic eruptions, which naturally emit reflective particles into the atmosphere. These diverse efforts reinforce the UK’s emerging leadership in climate intervention research.
While Aria stresses that reducing fossil fuel use remains the top priority, the program acknowledges the possibility that geoengineering could serve as an “emergency brake” if climate tipping points become unavoidable. “Life in the UK could become very difficult if any of these tipping points were triggered,” said Aria program director Prof Mark Symes. Thus, building a robust evidence base now may provide critical options for the future.