Cloud Whitening Could be a Black Day for Global Warming

A study unveiled at the European Geosciences Union has revealed that whitening clouds by using drops of sea water in order to reflect sun shine away from the Earth could be more harmful than helpful in preventing climate change and global warming.

However, the study revealed that using drops of sea water that were not the right size would cause the opposite effect and lead to increasing global warming. Piers Foster who works with the University of Leeds and who is working on a project on geoengineering techniques said, "The trouble is that clouds are very complicated; as soon as you start manipulating them in one way, there are a lot of different interactions."

Foster went on to mention that it would be difficult to adopt cloud whitening into practice unless a study could be simulated on a large scale."We need real-world data and we need modelling that tries to simulate clouds on more appropriate scales, and that means less than 100m or so, because if you look at a deck of stratocumulus it's not one big thing, it has pockets and cells and other features. Far more uncertain is the idea that you'd inject a particular drop size, because it won't stay that size for long. It will spread out, and that would be uncertain."

The idea of using water to create denser clouds originated over two decades ago. Part of the proposals included placing air ships that could constantly spray clouds. However, with further studies it has come to light that specific amounts of water are needed in different regions and too much water could be problematic as Kari Altersjkaer of the University of Oslo told the BBC during the study, which was unveiled in Vienna.

Altersjkaer admitted that South and Central America as well as western Africa would be the best places to introduce cloud whitening, but warned that unless the correct amount of salt water was dropped, cloud cover could be reduced rather than becoming whiter and more expansive. The report also revealed that 70 times more salt would be need to be carried in the region than originally thought.

"If the particles are too small, they will not brighten the clouds - instead they will influence particles that are already there, and there will be competition between them," she said. "Obviously the particle size is of crucial importance, not only for whether you get a positive or negative effect, but also whether particles can actually reach the clouds if they're too large, they just fall to the sea," added Altersjkaer.

Professor Salter who is one of the leading experts in the field of energy and geosciences agreed that the amount of water and salt was crucial to the success of any initiative.
"I agree that the drop size has to be correct and that the correct value may vary according to local conditions. However, I am confident that we can control drop size by adjusting the frequency of an ultrasonic pressure wave which ejects drop from micro-nozzles etched in silicon. We can test this at very small scale in the lab,” he said.

Photo credit: GeographBot