Here is the story, via Megan McArdle; an excerpt:
“On global warming, the problem is
ideologically I suspect it did cause me to …discount evidence which cut
against the way I wanted it to be in that case. My justification to my
self would be that I had seen [the environmentalists] be so wrong so
many times before, why should I trust them this time?” he says.
But when the science appeared irrefutable, Bailey changed.
It is important to distinguish two claims. The first is that a revenue-neutral carbon tax is, in expected value terms, a good idea. If nothing else, we cannot emit accelerating rates of carbon forever.
The second and more dubious claim is "a carbon tax is likely to solve the problem." That’s not so clear. China and India may not follow suit, the oil may be pumped and used anyway, and the elasticities may be working against us. I give the carbon tax about a thirty percent probability of significantly ameliorating global warming and that is assuming that we engage China in a constructive manner. A pessimistic view, however, does not refute the case for trying.
Addendum: Here is an interesting post on whether more information about global warming causes people to worry about it less.