The Great Global Warming Blunder - Review

Using ordinary regression, this month-to-month line is wrong: that is, the negative feedback implied by it is false.BUT - and I want everybody to pay attention here - the ordinary regression line might very well be thewrong statistical model. That is, the month-to-month line-segments approach, at least to my ears, sounds like a better approximation to the physics than alinearregression. At the very least, more sophisticated time series models should be tried.

The data from month-to-month are correlated, obviously. But it is not clear to me that Spencer and other workers are properly accounting for this correlation when estimating feedback via regression. In my simulation I added in positively correlated data, to better approximate the real atmosphere. The situation is much the same: only in this case, we will be mis-estimating the actual regression line if we do not account for the correlation. There’s really no point in doing this, because methods for computing regressions in the presence of correlation are well known. Why they are so little used is anybody’s guess.

This doesn’t end it because Spencer, like many others, then decides the raw data looks too noisy - why oh why do people feel compelled to prettify their data! - and so smooths them with “running three-month averages” and then recomputes his feedback parameter.This unwise maneuver affects the regression estimates!The final results depend on the exact nature of the smoothing. Experiments I ran show the naive, regression-estimated feedback parameter can veer either direction, higher or lower depending on the amount of smoothing and correlation. The month-to-month line segments can, too. In other words, smoothing is nuts.

I want to stress - and stress again and stress some more - that even if Spencer and other workers used the correct statistical methods, a simple glance at the raw data is enough to convince us that any pronouncements about estimated feedback parameters must be accompanied by more than a healthy dose of uncertainty. This uncertainty is rarely given; Spencer does not give it. As it stands, it could be either negative or positive, each about equally likely.

Spencer realizes this in part, and so built a toy climate model (I use the word “toy” as physicists do, not as denigration, but as proof-of-concept) which incorporates his ideas about feedback to examine how the estimation methods work when the feedback mechanism is known exactly. What his result mean

for the diagnosis of feedbacks from satellite data is that when there is a mixture of radiative and nonradiative forcings of temperature occurring, natural cloud fluctuations in the climate system will cause a bias in the diagnosed feedback in the direction of positive feedback, thus giving the illusion of an overly sensitive climate system.[emphasis in original]

Very well. It’s Spencer’s model against the models of the IPCC. Who will win? Who knows? We do know that the IPCC models purposely incorporate positive feedback - and when the results are examined, they say, “Look at this dangerous positive feedback! Positive feedback, since it shows in the results of our models, must be real.” Circular thinking, of course.

PDO

Spencer, like many climatologists, indulges in some misplaced teleological language when discussing the PDO, the Pacific Decadal Oscillation, and its role in the climate. The PDO is - yes, it’s true - based upon a statistical model, a function of sea surface temperatures. Now, sometimes SSTs go up, sometimes they go down; the PDO attempts to capture these comings and goings in a single-number index. Experience has shown that the PDO oscillates in a rough, thirty-or-so-year cycle. Some have found that these oscillations are correlated with various changes in the climate: not just temperature, but other weather-important variables.

These correlations should not be surprising: whatever is causing the SSTs to change will be causing other changes in the climate system either directly or indirectly. It would be shocking if this were not so. But it would wrong to say, as many do say, that the PDO itselfcauseschanges in the climate. This admonition holds also for ENSO. Thus, it’s no good pursuing PDO or ENSO saying that they can account for the observed warming. They cannot. They might be used in a statistical predictive sense, but are of little use as explanations of why the climate changes.

Matters Miscellaneous

I can well understand Spencer’s frustration when encountering True Belief, a malignancy in activists and a near fatal affliction in some climatologists. But his frequent, plaintive reminders that nobody has yet acknowledged his work put me in the mind of the cry, “Fools! I’ll destroy them all!” I won’t say that Spencer is to climatology what Stephan Wolfram is to computer science or Gregory Chaitin is to information theory, but we get it already: climatologists are in love with their models and unfriendly towards the contrary evidence Spencer offers, evidence which may well prove true. A “little more humility might be appropriate” (p. 120) if he wants unconvinced audiences to take him seriously.

There’s a cute chapter on common logical fallacies rife in this heated science. My favorite is appeal to authority, most often invoked from the peanut gallery crying “Peer review!” when they hear a criticism they don’t like. To non-scientists, peer review must sound like magic, an assurance of correctness. But we on the inside know it for what it is: a weak filter of quality. It is a paper sword.

I wish Spencer would have left out the editorializing about matters economic and political. It’s unwise to commit resources to other fronts when the lines in front of you are not secure. Enemies will exploit the weaknesses of these secondary arguments and then trumpet their success in finding flaws. Ordinary observers will only hear that mistakes have been found and will dismiss the entire work, if that is most comforting to them.

Overall

This book isn’t the last word in climate science, nor can it be used as the only word, but it does contain some good words. Spencer’s climate theories cannot be ignored and should be understood by all modelers, and for that reason alone, the book is worth reading.