The uncertainty principle
Over Thanksgiving, Eli was out in Colorado visiting Ethon, [for those who don't know, a rather large bird specializing in liver pecking] who offered a ride in the mountains. Coming down the hill at lickety split units of distance per second, Eli wondered if Ethon knew where the cliff was, and if he had a clue where to start stopping to avoid going over the edge. Ethon pointed out that he could fly and wondered what Eli's problem was. Eli silently wrapped his ears around his eyes, you don't mess with a big liver pecker but you can prey.
This is the situation that Nicholas Stern identified, and that Marty Weitzman tip-toed up to but did not quite go over the edge on in his review of the Stern Review which Eli reviewed yesterday. Weitzman concludes that
In my opinion, public policy on greenhouse warming needs desperately to steer a middle course, which is not yet there, for dealing with possible climate-change disasters. This middle course combines the gradualist climate-policy ramp of ever-tighter GHG reductions that comes from mainstream mid- probability -distribution analysis (under reasonable parameter values) with the option value of waiting for better information about the thick-tailed disasters. It takes seriously whether or not possibilities exist for finding out beforehand that we are on a runaway-climate trajectory and –without “leaving it all up to geoengineering”– confronts honestly the possible options of undertaking currently politically incorrect emergency measures if a worst-case nightmare trajectory happens to materialize.This might have been a good policy ten or fifteen years ago, when some, including Eli were arguing for it, but today we are a lot closer to the cliff, wherever it may be, and probably closing rapidly on the beyond this point we are going over point (see for example the IPCC WGII take on where the cliffs might be) . Weitzman and other to be named later assume that there is lots of time to organize a response. Hansen and now Pachauri think not. The Roadrunner never tells.