The switch from ‘scepticism’ to an overtly anti-science, and anti-scientist, position has paid some dividends for the advocates of delusional views on climate change. Although the only wrongdoing in the CRU harassment/hacking campaign was that of the hackers and their allies (more on this soon), the false charges of scientific fraud got much more media attention than their refutation, and the early responses to alleged FOI breaches (including that of some pro-science writers such as George Monbiot) failed to recognise of the deliberately vexatious misuse of FOI by the anti-science group. In this context, the discovery of a genuine error in the 1700 page IPCC Fourth Assessment Report regarding projected changes in glaciers could easily be spun into something much bigger.

It seemed for a little while as if the delusionists had scored another win, when Phil Jones, the scientist who has been most viciously target by the hackers/harassers gave an honest answer to a deliberately loaded question prepared by them and put to him in a BBC interview

BBC: Do you agree that from 1995 to the present there has been no statistically-significant global warming? Phil Jones: Yes, but only just. 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. Achieving statistical significance in scientific terms is much more likely for longer periods, and much less likely for shorter periods…

This was headlined by the Daily Mail as “Climategate U-turn as scientist at centre of row admits: There has been no global warming since 1995?.

But, now it looks as if this is starting to backfire. Anyone who has successfully completed a basic course in statistics knows that “statistically significant” has a special meaning which bears almost no relationship to the usual sense of the term “significant”, and this fact is beginning to sink in.



The statement “there has no statistically significant warming since 1995” can better be stated as “if we ignore all the data before 1995, we don’t have enough data points to reject, with 95 per cent confidence[1], the hypothesis that the observed warming since 1995 has been due to chance variation”. That isn’t true if you replace 1995 with 1994 or any earlier date going back to 1970. It’s clear that those who dreamed up this talking point knew enough stats to realise that they were being deliberately deceptive, and that ignorant “sceptics” would read the statement as saying “no significant warming since 1995”. They were right and the talking point ran through the delusionist commentariat and blogosphere at record speed.

The only problem is that such an obvious lie can be, and has been called out, and is essentially impossible to defend, except by an admission of culpable ignorance or gullibility. Here’s The Economist (not exactly zealous on climate change) responding to the original Daily Mail article (h/t Tim Lambert)

This led to a Daily Mail headline reading: “Climategate U-turn as scientist at centre of row admits: There has been no global warming since 1995.” Since I’ve advocated a more explicit use of the word “lie”, I’ll go ahead and follow my own advice: that Daily Mail headline is a lie. Phil Jones did not say there had been no global warming since 1995; he said the opposite. He said the world had been warming at 0.12°C per decade since 1995. However, over that time frame, he could not quite rule out at the traditional 95% confidence level that the warming since 1995 had not been a random fluke. Anyone who has even a passing high-school familiarity with statistics should understand the difference between these two statements.

And here’s Brad DeLong skewering Russ Roberts as the lyingest economist alive, then downgrading the charge to one of reckless gullibility when it became clear that Roberts had relied on a Daily Mail headline, thereby making a complete fool of himself.

Looking at the responses of ‘sceptics’ to this episode we can distinguish four or five sets (depending on your views about set theory)

1. Those who originally designed the “no significant warming” talking point. Members of this set are deliberate liars playing on the ignorance and gullibility of their target audience. As far as I can tell, the first to put this line forward was Richard Lindzen of MIT, who put it up in early 2008, tied to the cherry picking “no warming since 1998” claim (see here). Lindzen certainly has the training to know how dishonest this is. More recently, it’s been pushed by Lord Monckton and others, who may perhaps fall into set 2.

2. Those who quoted the question and answer, and took “not statistically significant” to mean “insignificant”. Members of this set have demonstrated, first that they don’t know basic statistics and second that, despite claiming to “make up their own minds” about climate science, they haven’t bothered to acquire even the most basic knowledge necessary to such a task. At a minimum, members of this group are lying to themselves, in the same manner as other exemplars of the Dunning-Kruger effect

3. Those who relied either on the Daily Mail headline, or on the second-hand versions propagated by members of set 2. Members of this set have demonstrated both a high level of gullibility and ignorance of the basic data on climate change, which clearly shows a substantial increase in temperatures since 1995 (whether or not this is statistically significant). Again, they are lying to themselves if they think of what they are doing as “making up their own mind”. Here’s

a graph of the data.

4. Those who recognised the dishonesty of the Daily Mail line, but stayed silent out of loyalty. As far as I can tell, most of those on the delusionist side with even basic statistical knowledge (McIntyre, McKitrick and Wegman for example) have kept quiet, in McIntyre’s case linking to the BBC interview without comment and letting his audience draw the necessary silly inferences. If anything remotely comparable had been put forward by a supporter of mainstream science, they would have been all over it.

5. Those genuine sceptics who pointed out the dishonesty of the claim, and called out those on their own side of the debate who promoted it. Obviously, members of this set deserve some serious respect and attention in the future. Unfortunately, the intersection between this set and the set of “sceptics” in the currently prevailing sense appears to be the empty set[2]

So, a challenge to those who think there is a debate to be had here, as opposed to a series of silly talking points to be whacked down with greater or lesser success. Can you

A. Provide a coherent defence of the “no statistically significant warming since 1995” claim. To limit trollery, this should begin with a statement, in your own words, of the basic hypothesis testing framework in which this concept arises? ; or

B. Give an argument as to why anyone should pay any attention to those on the “sceptical” side who have formulated this claim, propagated it in some form or another, or allowed it to pass without comment?

I will award grades to the responses.

Diversions to other talking points, general delusionist rants and so on will be deleted.

fn1. “Reject with 95 per cent confidence” also has a special meaning, subtly different from “reject with 95 per cent probability of being right”, but the difference doesn’t matter much in the current context

fn2. Corrections on this point will be gratefully accepted and prominently publicised.