Consequences of Climate Change

Climate change will have both negative and positive consequences, although the positive are largely ignored in the public discussion. There is no a priori reason to expect an average global temperature a few degrees warmer to be worse for humans than the current climate, although it might be. I will run through positive and negative effects, arguing that their size is sufficiently uncertain that we cannot sign the sum — the same conclusion I argued for the effect of population growth fifty years ago when it played a similar role in public discussion.