If you want a well-worked-out cost/benefit analysis of action on climate change, watch this:
It's somewhat simplified, but it doesn't make any of the idiotic mistakes and assumptions that Lomborg makes. It's entirely rational, and would meet with an approving nod from any competent game theory-aware economist.
Most importantly, it separates out the things that we know and can control (our response to climate change) and those things we can't know for certain (what climate change will consist of.) Lomborg's mistake is that he pretends to know what's going to happen, and makes a prediction based on that; where this video is smart is showing that even if you aren't sure what's going to happen, you can make your decision based on the expected outcomes.
If you act and there was no climate change, there might be a global recession. That would be bad. Very bad. If you don't act, though, and it is true, the economic, political, and social side effects will absolutely dwarf anything that the economic hit could consist of. The point (which is absolutely valid) is that because we don't know whether or not global warming will happen, and the consequences of inaction if it DOES happen are so disastrous, we should act even if it turns out that nothing was going to happen. The possible negative side-effects of inaction are simply too much greater than the possible negative side-effects of action for inaction to be a rational choice.
(It's a little bit like a modern-day Pascal's Wager, without the "which god?" cutout.)
Now, like most game theory, this video doesn't really address the central problem here: cost/benefit distribution. The wealthy stand to take a disproportionate hit from action, whereas the worst suffering from global warming will almost certainly be by the poor: the wealthy can insulate themselves from the side effects.
Yes, the economic hit may be disastrous for large capital-holders. Whereas labour's pretty much stuck where it is, capital can range pretty much as freely as is necessary. Because of the ease of moving capital these days, it's not tremendously difficult to move your capital away from regions disproportionately affected by global warming, and maybe even make a buck or three from the panicked spending that is sure to arise when the real side-effects of global warming start hitting the globe in earnest.
And, naturally, it ain't the poorest and most vulnerable that Beijing, Washington, Ottawa, Mexico City, Moscow, London, Paris, and all the other big polluters are listening to. It isn't the poorest that are employing hired-gun economists like Lomborg to provide cover fire. It's the large capital holders that want to extract as much wealth as they can before the music stops.
Said it before, I'll say it again: I'm not anti-capitalist or anti-market. Far from it. It's just that any political or economic analysis needs to take these things into account when deciding on who to pressure, how, and why. The video doesn't take that into account, but it's still a damned good analysis of the situation, and I'd recommend it to everyone.