Occasional Reason contibutor and Harvard University physicist Russell Seitz proposed a novel mechanism—microbubbles—for cooling the earth at the Asilomar International Conference on Climate Intervention Technologies at Asilomar in California last week. PhysOrg.com reports:
The bubbles in turbulent water already provide "undershine" beneath the surface, and these contribute around 0.1% of the Earth's reflectivity, or albedo. Harvard University scientist Russel Seitz's proposal is to use ships to pump tiny "microbubbles," about 0.05 0.002 mm* in diameter, into the sea as they travel, in a strategy he terms "Bright Water". Seitz said the bubbles would, in effect, act as tiny mirrors containing air, and could be created by mixing water supercharged with compressed air with swirling jets of water. This would emulate and amplify a naturally occurring phenomenon.
Using computer modeling, Seitz discovered that a concentration of only one part per million of microbubbles can double the reflectivity of water, and could cool Earth by up to 3°C if the system could be deployed. Adding microbubbles to a square kilometer of ocean is feasible, but Seitz admitted that scaling it to cover an entire ocean would be technically difficult, not because of the energy requirement, which he said would be equivalent to about 1000 windmills, but because of the fact that the bubbles may not last long enough to effectively spread over large areas.
*Correction: Seitz tells me that PhysOrg reported the wrong size for the microbubbles in his proposal. Instead of 0.05 mm, they should be 0.002 mm.