Can radical ‘cloud-brightening’ proposal help curb global warming?

Monsoon clouds loom over the Kathmandu skyline, August 12, 2012. The monsoon season in Nepal typically last from …Geoengineering — the use of technology to make large-scale changes to the environment — has been making the news lately.

Similar to a previous idea, a new proposal for "marine cloud brightening" suggests using a network of remote-controlled, self-sustaining Flettner ships to spray salt water into the upper atmosphere over the oceans. This would create long-lasting clouds which would reflect more sunlight back into space and help cool the planet. Using salt water — instead of the previously-proposed sulphur dioxide — would prevent potential damage to the ozone layer.

Methods like these could have unexpected effects, with some scientists saying that cloud brightening over the Atlantic Ocean could cause the South Atlantic to cool, which would mean less evaporation of ocean water into the air and less rainfall over the Amazon rainforest, turning the area into a desert. However, according to the lead author of the paper, Jonathan Latham of the National Center for Atmospheric Research in Boulder, Colorado, this new study shows that marine cloud brightening would actually lead to more rainfall over land.

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General criticisms of geoengineering include just how effective any of these methods would be, the costs involved, potential weaponization, the moral hazard of working on a stop-gap method instead of dealing with the real problem of carbon emission, and even termination shock — the rapid heating of the planet that could occur if we were to suddenly stop using these methods (due to breakdown or lack of resources).

Possibly the most important fact acting against us is that we don't have a complete understanding of the atmosphere and how everything interconnects. Going ahead with any of these projects is seen by many as irresponsible without knowing more about the potential side-effects.

The authors of the paper — led by Latham, who first proposed geoengineering back in 1999 — are not ignorant to these issues, though. The paper apparently uses very cautious wording, and asks other scientists to consider the idea and try to pick it apart. Also, the experiment outlined in the paper moves in small steps, from choosing a very small area to conduct the experiment with one ship, to see what happens, and then expanding the area with more ships as they learn more, all while emphasizing international cooperation.

The paper will be published this month in the journal Philosophical Transactions of the Royal Society.

(Photo courtesy Reuters)