City responds to questions

Published on May 04, 2024

City responds to questions about a University of Washington cloud brightening experiment on the U.S.S. Hornet

Following a series of recent news articles appearing in local and national headlines in early April, the City of Alameda was made aware of a University of Washington cloud brightening experiment that was taking place without the City’s knowledge on the deck of the U.S.S. Hornet involving spraying sea salt water with a machine resembling a snow maker. Upon learning of the spraying experiment, the City instructed the U.S.S. Hornet and the University of Washington to halt the experiment on the grounds that it was in violation of the City’s lease with the U.S.S. Hornet. The U.S.S. Hornet and the University of Washington have confirmed that they have stopped spraying in compliance with the City’s instruction.

City staff are working with a team of biological and hazardous materials consultants to independently evaluate the health and environmental safety of this particular experiment. In particular, the City is evaluating the chemical compounds in the spray to determine if they are a hazard either inhaled in aerosol form by humans and animals, or landing on the ground or in the bay. The findings from the evaluation will be provided to the public, and shared with the City Council for consideration in June. At this time, there is no indication that the spray from the previous experiments presented a threat to human health or the environment. 

This is a research project led by scientists from the University of Washington investigating the feasibility and potential impacts of reducing climate warming by intentionally increasing the reflection of sunlight by enhancing marine clouds (aka “cloud brightening”). You can find more information on the University of Washington Facility and the Marine Cloud Brightening Program on the USS Hornet’s website looking under "exhibits" https://uss-hornet.org/visit-hornet/exhibits.