Jim Manzi, who believes we have an anthropogenic climate change problem, (or at the least, someone unverifiably claiming to be Jim Manzi) nevertheless remains in the model-skeptic camp. He asks the following in response to Oreskes’ presentation:
Page 64 is pretty amateurish – “many model-based predictions have come true”. Really, I have a causal model for predicting the winner of baseball games – the team that bats first wins. Look at this long list of predictions that my model has made correctly.
Pages 65 – 69 use the intense 2005 hurricane season as confirmation of predictions. 1. Too bad about 2006. 2. There is a reason that hypotheses are subject to falsification tests rather than confirmation tests .
Let me take these in reverse order.
The latter criticism of Oreskes is relatively stronger. A fair consideration of the point requires understanding of a few things:
- The climate system doesn’t care very much about whether the tropical storms make landfall and 2006 was not unusually quiet
- Atlantic hurricanes correlate inversely with El Nino and 2006 was an el Nino year
- There are other components of tropical storm variability which are not known. The question of whether the 2005 Atlantic season was so anomalous as to require explanation is something of a judgment call. (The next few months will tell us something, as a negative El Nino anomaly, favorable to Atlantic hurricanes, has returned.)
As an aside I say that the lesson of New Orleans is not so much that the age of superstorms has arrived, though in fact it might be so. The lesson of New Orleans is that society should listen to well-informed people who say “listen to me before it’s too late!” before it is, actually, too late.
In summary, though, the very peculiar Atlantic tropical storm season of 2005 doesn’t constitute a trend in itself. It is however, part of a trend, and that trend is consistent with predictions. It certainly doesn’t argue against the climate change consensus, and the very high sea surface temperatures of late support it.
On the first point I must disagree with Jim and agree with Oreskes.
The list of validated predictions is long and extraordinary, in the context of the near-stationary climate of historical times. It can be argued that Oreskes missed a very important one: cooling of the stratosphere, which is inconsistent with solar forcing which would warm the entire depth of the atmosphere.
Polar amplification, nighttime amplification, these are robust (all models that can replicate contemporary climate from primitive equations do this) predictions of dramatic change matched by robust observations. This is not cherry picking as Manzi suggests. If it were cherry picking he (or anyone) could identify comparably robust comparably unprecedented changes that were predicted by most GCMs that didn’t happen at all.
Am I missing something? If so, please enlighten me.
So, Jim or some person claiming to be Jim, on what basis do you assert that you “don’t think the models are validated“? As for the necessity of the models to constrain the sensitivity, even that isn’t entirely crucial. We still have theory and (if you don’t go along with some of your ‘conservative’ allies in ignoring any evidence that implies the world is more than 10,000 years old) pretty extensive paleoclimate evidence.
By the way, testing models against paleoclimate is one of the best ways to validate them. For the most part it works out OK, though in very warm periods (the Eocene, notably) the results have been sort of funky. Sriver and Huber of Purdue claim to have worked this out, though. On their theory, it appears that the tropics are less heated than the poles in hot worlds because a good deal of heat is transported poleward by relatively more active tropical storms.
The sensitivity range question was handled admirably by Annan and Hargreaves. James Annan stops by occasionally and may want to elaborate. James is more concerned about tendencies to exagerate the high end, but I think even Lindzen, if pressed, doesn’t take a position much below the low end.