Bjørn Lomborg writes today at Forbes.com:

Evidence is growing that relatively cheap policies like climate engineering and non-carbon energy research could effectively prevent suffering from global warming, both in the short and long term. Unfortunately, political leaders gathering at a special meeting of the United Nations in New York this week will focus on a very different response.
They will make many of the most important decisions on how to respond to climate change over the next decade. They are expected to thrash out political disputes like how much carbon rich and poor nations should agree to cut. The real question that must be addressed is: Do we want to be the generation that promised so much but failed to solve global warming? We will not be judged by our descendants on our rhetoric, nor on the scale of our promises. We will be judged on what we deliver.
We have failed to rein in emission rises despite sincere and well-meaning promises made in Kyoto in 1997 and earlier, because carbon cuts are expensive to enact. That problem is only going to grow as our promises become more ambitious.

The rest here.