Sunday, January 08, 2006

Climate Predictability

Henk Tennekes has a skeptical take on climate predictions over at Roger Pielke Sr's blog. It's a digressive critique, but I think his main point is that we have little evidence for the reliability of climate models predictions. As far as I can tell, the only real evidence he presents is the fact that, as Lorentz has shown, long term predictions are highly uncertain in chaotic systems. In the comments, Roger Pielke gives a couple of examples of events that he claims climate models can't even postdict. Tennekes' conclusion is that we don't know enough about climate to attempt to manage it, and hence should concentrate on adapting to whatever changes occur.

“The constraints imposed by the planetary ecosystem require continuous adjustment and permanent adaptation. Predictive skills are of secondary importance.”

Today I still feel that way. I cannot bring myself to accept any type of prediction paradigm, and choose a adaptation paradigm instead. This brings me in the vicinity of Roger Pielke Sr.’s emphasis on land-use changes and Ronald Brunner’s modest bottom-up alternatives. It goes without saying that I abhor such dogmas as various claims to Manage The Planet or Greenpeace’s belief in Saving the Earth. These ideologies presuppose that the intelligence of Homo sapiens is capable of such feats. However, I know of no evidence to support such claims.
Plausible as this argument is, I can't accept it fully. Yes, we should prepare to adapt, but when we see an uncontrolled forcing being steadily increased, with additional evidence that it is already having significant effects, worrying about exctly how predictive our models are may be beside the point. When you smell smoke, it's not necessarily a good idea to wait until you see flame before evacuating the building.

If his point is merely that we need to try to assess how good (or bad) the models are, I'm with him 100%. That's a problem for mathematics, physics, climatology, and history.