To defend himself, he argues that he has never denied the reality of climate change; he has just always contended that the cost of trying to cope with the problem outweighs the possible benefits. As new ideas have surfaced for how to cope, he has reconsidered, and apparently some solutions now meet his cost/ benefit criteria.
For me, the frustrating thing about Lomborg has always been that he assumes that the world has some set amount of money that it will devote to solving a few large scale problems, and therefore the choice for society is which problems deserve attention. This is of course foolish: the world can choose to address all or none of these macro-problems, while spending its collective time and energy on any of a variety of other pursuits. Why is the question, "Should we help people in Africa improve their access to drinking water or fight terrorism?" rather than, "Should we do both rather than investing in pills that make our poop glitter?"
I do like the fact that his latest book seems to be focused on, "How shall we best strive to cope with a problem?" rather than how to dismiss serious issues because others are allegedly more serious. Keep on this track, Bjorn, and I won't be embarrassed to bring up your work in class!
Hat tip to Marginal Revolution for noticing the Guardian piece.