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West coast scientists experiment with reducing the amount of sunlight over American soil: report

April 10, 2024 | | Print Article

California scientists recently began an experiment to test whether they could reduce the amount of sunlight penetrating the Earth’s atmosphere.

Scientists say this unique geoengineering strategy, known as marine cloud brightening, could be the solution to slowing down climate change.

The way it works is that “researchers spray microscopic sea salt into the air over the ocean to boost clouds’ reflectivity,” meaning “less sunlight is absorbed,” according to a report from the San Francisco Chronicle.

The sunlight is instead reflected back into space, which, one, cools the Earth, and two, makes the clouds look brighter.

“A white car in a parking lot on a sunny day is going to be cooler than a black car … same idea, “Lynn Russell, an atmospheric chemist at UC San Diego’s Scripps Institution of Oceanography, told the Chronicle.

On Tuesday, April 2nd, scientists from the Marine Cloud Brightening Program boarded the decommissioned aircraft carrier Hornet in Alameda and began using it for their first-of-its-kind experiment.

“The scientists from the University of Washington are experimenting with the size and concentration of sea salt particles emitted from a spray machine,” according to the Chronicle.

“Cloud brightening has been simulated by computer models, but the fieldwork is the first of its kind in North America and only the second of its kind in the world. The foggy climate of the Bay Area, the researchers say, is ideal for these experiments,” the paper notes.

Because scientists are just now beginning to test marine cloud brightening, it’s not clear if it’ll even work.

“Simulations project that if 15% of Earth’s marine clouds were brightened, the globe would cool by roughly a degree, said Rob Wood, the lead scientist for the project and a professor at the University of Washington,” according to the Chronicle.

“If you increase the number of cloud droplets by increasing the number of sea salt particles, it’s like increasing the number of mirrors to reflect sunlight back to space,” Wood said.

The great, tragic irony is that human aerosol pollution HELPS this process — and since pollution has declined in the last few decades, the Earth has only gotten hotter and hotter.

“How much extra warming we get now from aerosol reductions is kind of telling us how much cooling we could have if those aerosols were somehow returned into the system,” Wood said.

One way to accomplish this, of course, is by spraying clouds with salt, which is exactly what the scientists aboard the Hornet did Tuesday. In the next few months, they’ll observe the atmosphere to see what happens.

“We take those measurements and the (weather) conditions on the flight deck … and we’ll see how the model simulations of the plume compares to what we measure,” Sarah Doherty, the director of the program and an atmospheric scientist at the University of Washington, said.

It’s a game of precision. If the salt is too big, it’ll create heavy clouds and produce rain. If the salt is too small, the brightening effect will be negligible.

Either way, local residents aren’t expected to notice anything different this week or, really, anytime soon.

That said, there are risks to this strategy.

“The way I usually sum it up is, every time this subject comes up, I simply ask people to tell me of a large-scale human modification of the environment that’s ever gone well,” Andrew Gettelman, a scientist specializing in clouds and climate change at the Pacific Northwest National Laboratory, told The Seattle Times.

“Nobody’s come up with a good example for me. It may have gone well for us, but not for the environment,” he added.

There are also concerns about the global outcomes of marine cloud brightening technology, according to Graham Feingold, the lead for the cloud, aerosol and climate program at the National Oceanic and Atmospheric Administration’s Chemical Sciences Laboratory.

“If we think we can cool the planet by half a degree centigrade, just as an example, on average, what does that mean for somebody living in the Amazon or in the United States or in Africa?” he said. “There’s a potentially big difference in how this might play out in different parts of the world.”

Vivek Saxena
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