Argument: Geoengineering is just as likely to damage the environment as help
Ken Caldeira at the Carnegie Institution of Washington told New Scientist: "Personally, as a citizen not a scientist, I don't like geo-engineering because of the high environmental risk. It's toying with poorly understood complex systems. I think the Earth's system is so complicated that our interfering with it is very likely to screw things up and very unlikely to improve things," he says. "And this is the only planet we have."
Alan Robock. "20 reasons why geoengineering may be a bad idea". Bulletin of the Atomic Scientist. 2008: 20. Unexpected consequences. Scientists cannot possibly account for all of the complex climate interactions or predict all of the impacts of geoengineering. Climate models are improving, but scientists are discovering that climate is changing more rapidly than they predicted, for example, the surprising and unprecedented extent to which Arctic sea ice melted during the summer of 2007. Scientists may never have enough confidence that their theories will predict how well geoengineering systems can work. With so much at stake, there is reason to worry about what we don’t know.
Molly Bentley. "Guns and sunshades to rescue climate". BBC. 2 Mar. 2006: current computer models are not up to the task of predicting the consequences of large-scale plans such as Earth shades."
Alan Robock. "20 reasons why geoengineering may be a bad idea". Bulletin of the Atomic Scientist. 2008: "12. Human error. Complex mechanical systems never work perfectly. Humans can make mistakes in the design, manufacturing, and operation of such systems. (Think of Chernobyl, the Exxon Valdez, airplane crashes, and friendly fire on the battlefield.) Should we stake the future of Earth on a much more complicated arrangement than these, built by the lowest bidder?"