Before The Wisdom of Crowds, of course, there was Extraordinary Popular Delusions and the Madness of Crowds. Delusions of which the recent, but now hopefully fading, AGW excitement is but one example. The point here, as the previous post tried to make clear, isn't that AGW isn't happening -- it probably is. The point is simply that the certainties of costs and the uncertainties of benefits from proposed carbon emission reduction schemes make the drive to implement them inexplicable on a rational basis.
If, on the other hand, this drive has more the character of a cultural fad, driven by irrational forces, , then it becomes more understandable, and the clues that this is the case with the AGW issue are everywhere. Note, for example, how its adherents tend to elevate it above the level of scientific theory to that of dogmatic doctrine, to the point where some have suggested criminalizing "heretics" who question it. Note too the way in which its adherents will refuse to countenance the possibility of any benefits to warming at all, as though the present climate is in such a Goldilocks condition of perfection that any deviation will lead to apocalypse. Or the way in which they refuse even to think about any other means of dealing with the potential problems of climate change -- e.g., carbon capture, geo-engineering -- than through huge forced reductions in global carbon emissions, regardless of the economic costs and questionable viability of such an approach. Or the way in which, at the first hint of rational skepticism, they lapse into irrelevant, moralistic rants about wasteful lifestyles, consumer societies, capitalist depradation, limits to growth, industrial civilization, technology, plastic, war, and humankind as a cancer on the planet, etc., etc.
So it's impossible to avoid the observation that, once we get beyond the immediate level of some degree of climatic warming resulting to some degree from human activity, we're in the realm of a quasi-religious belief system, defended with the sort of righteous intensity that we see in True Believers of all sorts. It's perhaps not surprising, however ironic, that we see this kind of phenomenon turning up in an age of supposed unbelief, particularly among those who tend to pride themselves on their freedom from religious superstition. We all need some source of meaning and value, after all, and in the absence of the old Gods, "going Green", "saving the planet", etc. can serve as well as any other New Age substitute. What's pernicious here, though, is the attempt to use science as cover -- that is, to try to make science serve one's religious and political ends. In attempting this, the Greens at one end of the political spectrum, including the AGW believers, make the same mistake as the creationists at the other end.
UPDATE: See the next post in the series for a test of whether AGW concern is rational or quasi-religious at base.