In Slate, armchair economist Steven Landsburg examines the questions climate change policy advocates must answer. In particular, he notes that recognizing the fact of human influence on the global climate does not resolve the policy debate. There are many other scientific, economic, and ethical questions to resolve first, including the proper discount rate and level of societal risk aversion. I don't agree with every jot and tittle of Landsburg's piece, but I think it helps elucidate the complexity of climate change policy, even before one considers specific policy proposals and issues of institutional design.
Landsburg on Climate Economics: