From the April 2007 Atlantic, Greg Easterbrook states the following...
"Why, ultimately, should nations act to control greenhouse gases? One reason is that the cost of control is likely to be much lower than the cost of rebuilding the World. Coastal cities could be abandoned and rebuilt inland, for instance, but improving energy efficiency and reducing greenhouse gas emissions in order to stave off rising sea levels should be far more cost effective."

Makes sense to me. The National Academy of Sciences, hardly a liberal think-tank, has come down on the side of the fact of Global Warming, and of human-produced greenhouse gases having a significant impact on the phenomenon. Forgive me if I give more credibility to their findings than the posts of beardedbruce and a BBC science/opinion documentary.