Re: "the backlash is a wee bit overdone"
"initial value problem, which chaos theory in the layman's sense is mostly about"
Then the person, having studied the subject for their degree, should know better.
"attractor"
Ok, so we are agreed then that the atmosphere is a chaotic system, and climate modelling is building on top of a key feature that differentiates a chaotic system from a purely random system; the existence of attractors in the phase space?
If so, perhaps you could answer this question for me... I'll use the Lorenz attractor as a simple discussion point, since that is rather poetically shaped like a butterfly's wings :). The evolution of through the phase space orbits around one of the attractors (one of the 'wings') and at some point will switch to the other attractor and orbit that for a while before switching back etc. When switches back and forth will occur is unpredictable due to the chaotic nature of the equations. If climate is changing we must presumably be moving from one attractor to another, otherwise the system will just settle back into the current attractor's orbit. So given a chaotic system is generally characterised as one switching between quasi-stable sates, how appropriate would it be to use statistical methods on such a system? In general I would have thought such methodology would need to assume a simplified model behaving in a more linear manner, and would such a simplified model be sufficiently representative to make sensible predictions? I don't know the answer to this. I do know that, as with all model representations of physical systems, the only way to prove whether a model is a good fit (or not) with reality is to run actual physical experiments. Computer simulations are just fancy models, so anyone claiming to 'prove' (in the scientific sense of the word) anything with a computer simulation really does need a reality check. They have their place, but proof they are not.
Biting the hand that feeds IT
