Could brightening clouds combat global warning?

Researchers have revived the idea of brightening clouds to cool down the Earth.

Researchers have revived the idea of brightening clouds to cool down the Earth.

This type of geoengineering is designed to combat global warming by pumping salt water into the sky over the ocean. Dubbed "marine cloud brightening", scientists at the University of Washington including Rob Wood have described the experiment in the journal Philosophical Transactions of the Royal Society.

By using ships perhaps more suited to a science fiction novel, the vehicles would shoot salt water over the ocean. The water droplets would then form clouds that in theory would reflect more sunlight into space and lower Earth's temperature.

"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.

Wood believes that with enough interest from the scientific community, funding such an experiment would be possible. A small-scale trial would be the first step to ensure that there are no unwanted, long-term side effects.

Geoengineering uses technology to manipulate our environment. However, experiments including brightening remain controversial. Wood says that this is not a good enough reason to prevent studying the concept -- preferring "responsible scientists [to] test the idea than groups that might have a vested interest in proving its success."

The proposed small-scale experiment would involve deploying sprayers on a ship or barge to trial whether enough particles could be elevated in order to impact the cloud cover. An aircraft would then be used to monitor the physical and chemical characteristics of the particles and how they disperse, and afterwards, a fleet would be used to study cloud development. Finally, five to ten ships would spread out across 100km (62 miles) to track resultant clouds in partnership with satellite technology.

However, Wood acknowledges that any experiments would not a long-term solution to global warming. He said:

"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. I think we ought to know about the possibilities, just in case."

Image credit: John McNeill

(via The University of Washington)

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