You'd think the search for a solution to bleaching coral in the Great Barrier Reef would have scientists looking down into the ocean, rather than up at the sky. But clouds could be key to combating warming ocean temperatures blamed for the bleaching, say Australian researchers. They believe that "brightening" low-level clouds over the 1,400-mile stretch of coral reef—boosting their ability to reflect the sun's rays back into space—could "cool the water a degree or two, which is enough to prevent most of the damage," Daniel Harrison of the University of Sydney tells Australia's ABC News. It could work like this: Salt particles from the ocean would be directed at the clouds, triggering more water droplets to form and thus creating larger, denser clouds.
Cloud brightening was first proposed as a way to cool the planet some 30 years ago and one study claims it could offset the ensuing global warming if carbon dioxide doubled in the atmosphere, reports MIT Tech Review. But though research is ongoing—one company has spent seven years developing a nozzle to shoot the salt spray—trials have been few and far between. Australian researchers—who stress the need to reduce carbon emissions—now hope to determine, through computer modeling, if cloud brightening on a small scale would make a real difference. And there's a lot riding on the research. "Cloud brightening is the only thing we've identified that's scalable, sensible, and relatively environmentally benign," Harrison says. (A total wipeout of coral is possible.)