Mark Twain is famous for many a quote. In issues having to deal with climate changes, one of the more apt is: “A lie can travel halfway around the world while the truth is putting on its shoes”.
This weekend saw the truth finally finishing with her boots, when Phil Jones, former head of CRU, admitted to the BBC that there has been no statistically-significant global warming.
I also calculated the trend for the period 1995 to 2009. This trend (0.12C per decade) is positive, but not significant at the 95% significance level. The positive trend is quite close to the significance level.
There is much goodness to be had from that Q&A, among others Jones’ admission that the Medieval Warm Period was probably real. This would imply that the warming of the nineties is hence not human-induced. (see also WUWT here (original reporting) and here (commentary).
But as someone with a bit of statistical schooling, the quote given above proves to me the decrepit state of climate ‘science’ (and it infuriates me no end in the process).
Proper statistical hypothesis testing means formulating a null-hypothesis (H0) and an alternative hypothesis (Ha). The H0, for statistically technical reasons, is usually framed as a negative, while the Ha is expressed positively. As an example: If one would like to test the differences in IQ between a sample group of men and one of women, the H0 would be ‘There is no difference in IQ between men and women’, while the alternative Ha would be ‘There is a difference between the IQ of men and women’.
The way hypothesis testing works is showing that H0 cannot hold and therefore Ha, by inference, must be true. In fact, statistical hypothesis testing is only able to reject (or not) the null-hypothesis. In science, a threshold of 95% significance is used, meaning there is a probability of 5% or less that H0 is true, given the data. Or, in slightly more technical terms (but the importance if this is considerable): It means there is a probability of 5% of observing Ha when if fact H0 is true.
In terms of the trend in global temperatures, the H0 must have been ‘There is no trend in global temperatures between 1995 and 2009’, while the Ha would have been ‘There is a positive trend in global temperatures between 1995 and 2009’. The admission by Phil Jones that that he wasn’t even able to reject the H0 hypothesis (let alone demonstrating that we humans are responsible) is a HUGE admission.
It doesn’t matter a damn if he saw a positive trend, or that it was ‘quite close to the significance level’. The simple fact is that the trend he observed was NOT significant, was not conclusive proof that H0 should be rejected. By his own admission he was not able to show that H0 does not hold. Ergo H0 does still hold, ergo there is no trend, positive or otherwise, to global temperatures between 1995 and 2009. Had he been a scrupulous, conscientious scientist he would have reported the fact and that would have been the end of the matter. But instead he chose to ignore his own calculations and latch on to the UN induced panic for ideological reasons and/or precious grant money.
This admission alone should be reason enough to cast Phil Jones (and all those like him) outside, where there is much wailing and gnashing of teeth. Phil Jones is a charlatan, as are all those like him.