The environmental impact was one concern raised by readers following our post detailing the hurricane-supression system proposed by Bill Gates, former Microsoft chief techology officer Nathan Myhrvold and others. In response, one of the people working on the project in Myhrvold's Intellectual Ventures Lab has posted an explanation on the company's site.

"This type of technology is not something humankind would try as a 'Plan A' or 'Plan B,' " writes Paul "Pablos" Holman in the Intellectual Ventures post. "These inventions are a 'Plan C' where humans decide that we have exhausted all of our behavior changing and alternative energy options and need to rely on mitigation technologies. If our planet is in this severe situation, then our belief is that we should not be starting from scratch at investigating mitigation options."

Pablos also posted that as a comment on our original post.

David Nolan, the University of Miami professor we spoke with for the initial post, has since expressed additional doubt about whether the concept would work at all. The plan, as outlined in patent filings by Gates, Myhrvold and others, appears to rely largely on a technique for pushing warm water down to alter the surface temperature of the ocean, rather than bringing cold water up.

Here's what Nolan says:

If that's the case, it's even less likely to work. Some of the warm water would be replaced by cold water coming up from below, but some of it would be replaced by warm water converging from outside the region. Also, it's very hard for cold water to come up from below, as it is cooler and therefore more dense than the warm water above. (When warm fluid lies over cold fluid, as in 99.99% of the ocean, vertical motions are strongly suppressed. This is called "stratification.") Similarly, it's hard for warm water to go down. The idea of using breaking waves to make a column of water that is slightly higher than sea level is a good one, but because it is warmer, the whole column may not even weigh more than the surrounding water even if it is taller.

Pablos from Intellectual Ventures Lab notes that the company will be providing more information about the project later this year, so apart from the environmental questions, it will be interesting to see how they address the issues Nolan raises.