>If you seriously believe that rising carbon levels constitute a catastrophic (or even existential) threat, then you should be open to these approaches.

My feeling is that a lot of environmentalists see climate change on the same way that fundamentalists see sexually transmitted diseases: as God (or nature’s) punishment for our immoral ways. Thus the solution is always change your behavior and stop doing the things that you like to do( for example have sex or live in too big of a house or eat meat or have too many kids). I think a lot of environmentalists would be disappointed if we could come up with a technical solution to global warming that allowed us to continue our lifestyle pretty much unchanged, just like a lot of fundamentalists were disappointed that condoms, antibiotics, and birth control allowed people to have sex without a lot of the consequences they had been warning people about.