Experiment would test geoengineering

An experiment is being proposed to test the idea of pumping seawater into the sky to create clouds that would reflect sunlight and counter global warming.

A group of scientists, led by Professor John Latham at the University of Manchester, have suggested a three-stage test to see whether the geoengineering scheme could help to alleviate climate change.

In a report, published in the journal Philosophical Transactions of the Royal Society, they suggest that the first stage of such a test could involve deploying sprayers on a ship or barge to check that they can inject enough particles of the target size to the correct altitude. An aircraft equipped with sensors would also study the physical and chemical characteristics of the particles and how they disperse.

The next step would involve additional aircraft to study how the cloud develops and how long it remains. In the final phase, five-10 ships would be sent out across a 100km stretch of water to pump out particles. Satellites could then examine how much light the resulting clouds reflect.

“I would rather that responsible scientists test the idea than groups that might have a vested interest in proving its success,” says atmospheric physicist Rob Wood at the University of Washington, one of the other authors of the journal paper. The danger with private organisations experimenting with geoengineering is that “there is an assumption that it’s got to work,” he said.

Knowing that geoengineering is a controversial subject, the researchers are treading carefully: “We stress that there would be no justification for deployment of [marine cloud brightening] unless it was clearly established that no significant adverse consequences would result. There would also need to be an international agreement firmly in favor of such action,” they write in the research paper’s summary.