Politico: Researchers quietly planned a test to dim sunlight. They wanted to ‘avoid scaring’ the public – ‘Failed to notify officials in California about a test of technology to block the sun’s rays’
https://www.politico.com/news/2025/07/27/california-sunlight-dimming-experiment-collapse-00476983
Hundreds of documents show how researchers failed to notify officials in California about a test of technology to block the sun’s rays — while they planned a much huger sequel.
By CORBIN HIAR
Excerpt:
A team of researchers in California drew notoriety last year with an aborted experiment on a retired aircraft carrier that sought to test a machine for creating clouds.
But behind the scenes, they were planning a much larger and potentially riskier study of salt water-spraying equipment that could eventually be used to dim the sun’s rays — a multimillion-dollar project aimed at producing clouds over a stretch of ocean larger than Puerto Rico.
The details outlined in funding requests, emails, texts and other records obtained by POLITICO’s E&E News raise new questions about a secretive billionaire-backed initiative that oversaw last year’s brief solar geoengineering experiment on the San Francisco Bay.
They also offer a rare glimpse into the vast scope of research aimed at finding ways to counter the Earth’s warming, work that has often occurred outside public view. Such research is drawing increased interest at a time when efforts to address the root cause of climate change — burning fossil fuels — are facing setbacks in the U.S. and Europe. But the notion of human tinkering with the weather and climate has drawn a political backlash and generated conspiracy theories, adding to the challenges of mounting even small-scale tests.
Last year’s experiment, led by the University of Washington and intended to run for months, lasted about 20 minutes before being shut down by Alameda city officials who objected that nobody had told them about it beforehand.
That initial test was only meant to be a prequel. Even before it began, the researchers were talking with donors and consultants about conducting a 3,900-square mile cloud-creation test off the west coasts of North America, Chile or south-central Africa, according to more than 400 internal documents obtained by E&E News through an open records request to the University of Washington.
“At such scales, meaningful changes in clouds will be readily detectable from space,” said a 2023 research plan from the university’s Marine Cloud Brightening Program. The massive experiment would have been contingent upon the successful completion of the thwarted pilot test on the carrier deck in Alameda, according to the plan. The records offer no indication of whether the researchers or their billionaire backers have since abandoned the larger project.
A section of the Marine Cloud Brightening Program’s 2023 research plan. | University of Washington
Before the setback in Alameda, the team had received some federal funding and hoped to gain access to government ships and planes, the documents show.
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Growing calls for regulation
Solar geoengineering encompasses a suite of hypothetical technologies and processes for reducing global warming by reflecting sunlight away from the Earth that are largely unregulated at the federal level. The two most researched approaches include releasing sulfate particles in the stratosphere or spraying saltwater aerosols over the ocean.