I've been thinking a bit more about the green movement. I know the vast majority of greens will object to geoengineering and, as someone who's personal beliefs resonate with the green movement, this is causing me significant unease (despite me not advocating geoengineering). That said, one argument presented by objectors to geoengineering seems exceptionally weak to me - 'hands of mother Earth'. The problem to me is that the Earth is not pristine, we've been altering climate for hundreds of years. Comparison of geoengineered scenarios surely has to be against the best predictions of climate change, not pre-industrial settings. Would we be making things better than they are likely to be without geoengineering, not some hypothetical utopia that no longer exists?
I think I can rationalise this with my beliefs. I would like the world's climate to return to pre-industrial balance, but this is impossible, there is neither the political or societal will or desire from the vast majority to do this - we enjoy the trappings of progress to much. Given this, and our inability to wean ourselves of carbon, geoengineering has to be considered as part of a broader adaption strategy.