Futurist Ray Kurzweil says that he's not worried about managing global warming because by 2035 the majority of our energy will come from solar energy.
Today, solar is still more expensive than fossil fuels, and in most situations it still needs subsidies or special circumstances, but the costs are coming down rapidly — we are only a few years away from parity. And then it’s going to keep coming down, and people will be gravitating towards solar, even if they don’t care at all about the environment, because of the economics.
Truly, once solar is cheap, nothing will come near it.
Once problem with Kurzweil's theory, which is quite optimistic, is it won't solve some of the other problems inherent in global warming including the changes that are already built into our planetary system. So it makes sense to be doing more even if solar looks good.