Unfortunately, from there I think the authors went on an ill-advised over fitting expedition in order to make their models look better and explain more of the variance with the R^2 inflation. They played the volcano effects and lag and the temperature lags with little or no a prior reasoning for their actions.

I am guessing here and I need to read the paper again, but when one puts a model together like in this case and without regard to the dangers of over fitting and one gets a good fit it is difficult for the over fitter to understand how easy it can be to manipulate data to show something that might well not hold up out-of-sample.

Again as a layperson with one read of the paper I would have thought the authors would have better proceeded by simply explaining with a principled argument the data presented in Figure 1.

It is quite evident that a thorough audit of the McClean et al. (2009) paper — done in the same way as the audit CA-et-al did of the Steig Antarctica paper — would be most useful in constructively critiquing the McClean paper’s conclusions and in establishing the paper’s overall defensibility, or possible lack thereof, as the case may be. Lucia has started the auditing process over on her own blog with critical comments that echo some of the ones we see here.

(C H E [tongue] E K)

Careful. Taking the derivative doesn’t exactly “remove” a linear trend. Rather it transforms a linear function into a constant function, whose constant value shows the strength of the trend.

OTOH, unless I missed something, their study can only justify the conclusion that the derivative of the Southern Oscillation is a “dominant and consistent influence” on the derivative of mean global temperature.

The effect of this is to remove any linear trend. We know CO2 has been increasing approximately exponentially over the period of their data, which, according to the theory of climate sensitivity to greenhouse gas increases, should result in a linear increase in temperatures.

By eliminating any linear trends from the time series, all they’ve done is emphasise the effect of ENSO, already known to be the major influence on short-term variation. Their conclusion that “The findings presented here are consistent with the Southern Oscillation being a major driver of temperature anomalies,” is certainly not supported by their analysis.

They lucked out on scoring referees who’d dozed off during the first week of Calculus 101

I haven’t read the paper thoroughly, but I must admit that the first sentence in the Analysis and Results section gave me some pause: “We start by considering 12-month running averages of our data.” There seems to be widespread use of correlations later in the paper and I think that prior smoothing could make interpretation of results considerably more difficult.

I was going to suggest an audit of the paper, but then I noticed the following at the very end:

Acknowledgment. We thank Craig Loehle for comments on aspects of the statistical analysis used in the study.

I suspect that there will be a number of scientists who dispute that this paper “ends the debate.”