The Guardian:Bjørn Lomborg: $100bn a year needed to fight climate change
The first thing to point out is that this story, which is all over the Internets, is false, as you can see from the description in the first sentence in the Guardian story above: "The world's most high-profile climate change sceptic". Here's what the "sceptic" has been saying from the start, according to the Guardian's own collection elsewhere:
Bjørn Lomborg in his own words:
"This chapter accepts the reality of man-made global warming." The Skeptical Environmentalist, 2001
"Global warming is real and man-made. It will have a serious impact on humans and the environment toward the end of this century." Cool It, 2007In other words, he's explicitly and quite clearly a believer in man-made climate change. What he is skeptical about is what follows from that, namely the net costs of the warming itself and the cost-benefit analyses involved in particular mitigation strategies now -- especially attempts to suppress carbon emissions through various taxation schemes, enough to make a significant impact on climate. From what I can see, this skepticism too largely continues -- meaning that it's false in the first place to claim he was ever a climate change skeptic, and then doubly false, in the second place, to claim that he's now made a "u-turn".
What has changed is that he's now recommending a relatively modest carbon tax be levied, not as a means of suppressing carbon emissions (which was always either futile or dangerous, or both) but simply as a means of raising funds for research on alternate energy sources, geo-engineering, and adaptation. If you add carbon-capture and either sequestration or carbon re-cycling (see this) as research targets, then this makes sense. The only thing to add is that it's always made sense and doesn't require global circuses like Kyoto or Copenhagen to implement. In fact, it doesn't require carbon taxes either -- it can or should be funded just as any other research initiative is funded. So maybe Lomborg is just throwing the True Believers a bone.