Bay Area City Orders Scientists To Stop Controversial Cloud Brightening Experiment

Last month, researchers from the University of Washington started conducting an experiment on a decommissioned naval ship in Alameda to test if spraying salt water into the air could brighten clouds and cool the planet. However, their project was forced to stop this month after the city got word of what was going on. SFGate reports: According to a city press release, scientists were ordered to halt the experiment because it violated Alameda's lease with the USS Hornet, the aircraft carrier from which researchers were spraying saltwater into the air using "a machine resembling a snowmaker." The news was first reported by the Alameda Post. "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," the press release states. Specifically, chemicals present in the experiment's aerosol spray are being evaluated to study whether or not they pose any threats to humans, animals or the environment. So far, there isn't any evidence that they do, the city stated. The prospect of a city-conducted review was not unexpected, the University of Washington said in a statement shared with SFGATE. "In fact, the CAARE (Coastal Aerosol Research and Engagement) facility is designed to help regulators, community members and others engage with the research closely, and we consider the current interactions with the city to be an integral part of that process," the statement reads. "We are happy to support their review and it has been a highly constructive process so far." The marine cloud brightening (MCB) technique involves spraying fine particles of sea salt into the atmosphere from ships or specialized machines. These sea salt particles are chosen because they are a natural source of cloud-forming aerosols and can increase the number of cloud droplets, making the clouds more reflective. The particles sprayed are extremely small, about 1/1000th the width of a human hair, ensuring they remain suspended in the air and interact with cloud droplets effectively. By reflecting more sunlight, these brightened clouds can reduce the amount of solar energy reaching the Earth's surface, leading to localized cooling. If implemented on a large scale, this cooling effect could potentially offset some of the warming caused by greenhouse gases. You can learn more about the experiment here.

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