Of course there is nowhere else to look but to history to constrain what might happen, than to the past. I am not sure how Revkin jumps to his “Greenland, despite all of its drama (moulins, for example) — drama that focused my attention for a few years too — is a sideshow in the sea level question.” We don’t have the complete correspondence with Professor Alley, so don’t know, but it seems Professor Alley was, with his “If anyone is thinking that this paper means we can crank up the temperature without worrying about sea level, they should seriously re-think. Overall, a great and successful scientific effort leaves us with the knowledge that warming does tend to melt ice, and that contributes to sea-level rise.”

There’s so much we don’t know. And, as I said, we are driving the climate REALLY HARD. See http://johncarlosbaez.wordpress.com/2012/11/06/mathematics-and-the-environment-part-5/ and subsequent posts for some of the dangers which haven’t been considered at all in the IPCC or anywhere else.