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Marine Cloud Brightening: Shooting Saltwater at The Sky to Reduce Warming


Scientists have long thought using ships to shoot saltwater into the sky to form clouds that in turn have to ability to reflect sunlight back into space, thus cooling the atmosphere. Although this only sounds like a small patch to a much bigger hole, they are now considering their options, just in case.

Rob Wood, from the University of Washington, has recently published a paper where he describes the best possible way to test this concept and the ship they would have to use to spray water. The study also looks at the potential climatological impacts, as this kind of experiment has never been done before and uses climatology not just as an observatory science, but also intervenes on the processes that should take place naturally.

Their theory behind marine cloud brightening is that by shooting salt-rich water particles in the sky, long-lasting clouds could get formed because the particles would be smaller than normal water droplets, and would have a greater surface area.

“It turns out that a greater number of smaller drops has a greater surface area, so it means the clouds reflect a greater amount of light back into space,” Wood said. That creates a cooling effect on Earth. Marine cloud brightening is part of a broader concept known as geoengineering which encompasses efforts to use technology to manipulate the environment. Brightening, like other geoengineering proposals, is controversial for its ethical and political ramifications and the uncertainty around its impact. But those aren’t reasons not to study it, Wood said.

“I would rather that responsible scientists test the idea than groups that might have a vested interest in proving its success,” he said. The danger with private organizations experimenting with geoengineering is that “there is an assumption that it’s got to work,” he said. Wood and his colleagues propose trying a small-scale experiment to test feasibility and begin to study effects. The test should start by deploying sprayers on a ship or barge to ensure that they can inject enough particles of the targeted size to the appropriate elevation, Wood and a colleague wrote in the report.

A sensor-equipped aircraft would later on study the particles and the way they disperse in the air. The final phase of Wood’s experiment would be to send out 5 to 10 ships spread out across a 100 kilometer (62 mile) stretch to spray saltwater. The light reflection effects would be measured using satellites.

“It’s a quick-fix idea when really what we need to do is move toward a low-carbon emission economy, which is turning out to be a long process,” Wood said. “I think we ought to know about the possibilities, just in case.”

[via phys.org]

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