Dr Roger Pielke Sr on Climate Models & Predictions -- One Example

by Liberty and Power

Apropos of climate studies: Here is Dr Roger Pielke Sr on a recent paper in the Journal of Climate. The paper used “high resolution weather prediction models”. For “the eastern United States”, these regional models “predicted” very much higher temperatures “for five future summers” than did the global model from which the regional models were derived.

Dr Pielke listed some “remarkably serious shortcomings of the model study”. His final para reads:

“Equally disturbing (or it should be to anyone who values scientific credibility) is that a peer reviewed journal elected to publish this paper in this form in which untested predictions for decades into the future were presented, yet the global and regional model could not even skillfully simulate recent climate[emphasis added]. The publication of such clearly scientifically flawed research conclusions raises questions on whether the journal (in this case the American Meteorological Society Journal of Climate) is engaging in advocacy rather than being a balanced arbitrator of peer reviewed papers. Publishing predictions which are not tested, is not science.”
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I highlight two points: 1. Senior scientists -- not Dr Pielke alone -- have serious reservations about using global climate models 2. Some climate studies at least have to be taken with a pinch of salt. But only knowledgeable scientists can detect these. All that lay inquirers can do is remain aware that there do exist well-based problems in climate studies.

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William J. Stepp - 5/16/2007

I don't see how the law of large numbers underpins climate models.
That law assumes statistically independent observations (like the throws of a die, which should average 3.5 for enough throws to satisfy the law). Observed temperatures are not statistically independent. The temperature on June 30 in Chicago will be a lot closer to the temperature on June 29 than to that on January 1. Temperatures also appear to move in 1500 year cycles, with ice ages, little ice ages, and warming trends.

Here is a GIGO article, by a professor of statistics no less:

http://privatizationofrisk.ssrc.org/Chichilnisky/

Note the full-bore call for lots of statism.

Sudha Shenoy - 5/16/2007

Tim:

I refer you to Dr Pielke's comments (via the link.) He has a paper in which he argues that global climate models (the current ones) are much _less_ reliable -- if at all -- than local/regional ones. He is a strong advocate of looking at climate regionally.

Dr Pielke's main objection is to _untested_ predictions, _not_ to the direction of the predictions.

Undoubtedly warmer periods have clear advantages. The real problem is that the _IPCC_ insist that: increasing use of fossil fuels leads to undesirable levels of CO2 & therefore to undesirable heat. Hence the political attempts to 'reduce' the use of such fuels. Dr Pielke's paper (above) details the grave shortcomings of the models they use. There are other problems with the other components of their case.

Tim Sydney - 5/16/2007

Sudha,

1. Law of Large Numbers

My layman's understanding of climate models is that their statistical reliability is based upon the law of large numbers. See "The Basics of Climate Prediction" for an introduction).

So it would seem to me that there are at least prima facie grounds for taking "global" climate models and their most general predictions with a much greater degree of confidence than specific regional predictions. The later would presumably require at least an order of magnitude more data to deliver an equally confident result.

I suppose an analogy would be national versus municipal demographic forecasting. It's possible to make actuarially sound forecasts based on the first but the second is probably more of a gamble.

2. Icehouse is dry, Greenhouse is wet

Paleo-climatologists and geologists, for example, the University of Melbourne geologist, Ian Plimer in his article "The Past is the Key to the Present: Greenhouse and Icehouse over Time" (available online in PDF format here) have pointed out that in the deep history of the planet, "ice age" periods are usually dry periods and "hot house" periods the wet periods.

I don't think climate or earth scientists less skeptical of GW than Ian Plimer (a noted GW skeptic) would disagree with his generalisation here.

So all told AGW should make the earth on average wetter. The incidence of drought all told should be less. This would seem to be both a logically and empirically (ie from paleo data) well established finding.

Of course regions will vary, (in a sense there is no 'global climate' only lots of local climates), and maybe the distribution of 'wet' and 'dry' areas will change, but my guess is that we are still a very long way from being able to make any local forecasts.

For modern commercial farmers regional climate change uncertainty is just another source of uncertainty. Pricing , market and government policy uncertainties are all part of their business life. In all likelihood the later will almost certainly be more of a worry for farmers than the former.