How serious is the global warming threat?

Despite the media's and politicians' insistence that the science of global warming is "settled", there are good reasons to distrust climate model projections of future global warming. While the supposed scientific consensus is that mankind is very likely to blame for recent global warmth, this is mostly a statement of faith made from a position of relative ignorance about natural variability in the climate system. Since we do not understand what causes decadal- to century-scale natural climate variability, it has simply been assumed to either not exist, or to be relatively small. But even if predictions of catastrophic warming are accurate, the worldwide demand for energy is so large that there is little mankind can do without radically new energy technologies. Since it is only the wealthy countries of the world that can afford the R&D efforts to develop those technologies, punishing the use of fossil fuels, and the resulting negative impact on economies, might well delay the development of cost effective carbon-free energy sources that so many people are now calling for.