California Officials Halt Secretive Sunlight-Dimming Geoengineering Test

A University of Washington-led team attempted a solar geoengineering experiment last year in Alameda, California, using saltwater mist sprayed from a machine on a retired aircraft carrier to brighten clouds and reflect sunlight, aiming to cool the planet. The experiment, intended to last months, was abruptly halted after 20 minutes by city officials who were not informed beforehand, sparking criticism over the lack of transparency and local engagement. Internal documents reveal plans for a much larger follow-up test to cover 3,900 square miles off the coasts of North America, Chile, or Africa, which would have produced cloud changes detectable from space. The initiative, supported by billionaire backers and some federal funding, faced backlash due to ethical concerns and political opposition to weather manipulation. Researchers downplayed the potential weather impact, emphasizing the test's goal to demonstrate cloud-making technology, but critics highlighted secrecy and the risks of such geoengineering efforts. The status of the larger project remains unclear, with no indication it has been abandoned despite the Alameda setback.