Thus when Vergano explained his nut test, I accepted that as easy as the word of God is accepted by an elder, as the Dutch say. A typical case of confirmation bias. He writes:
"A decade after my first climate science epiphany, I was interviewing a chronic critic of global warming studies, particularly the 1998 “hockey stick” one that found temperatures in our century racing upward on a slope that mirrored a hockey blade pointed skyward. He argued vociferously that the study’s math was all messed up, and that this meant all of climate science was a sham.
I listened, and at the end of the interview, I gave him the nut test.
“What are the odds that you are wrong?” I asked, or so I remember.
“I’d say zero,” the critic replied. “No chance.”
That’s how you fail the nut test.
I had asked a climate scientist the same question on the phone an hour before.
“I could always be wrong,” the scientist said. Statistically, he added, it could be about a 20% to 5% chance, depending on what he might be wrong about.
That’s how you pass the nut test: by admitting you could be wrong.
And that’s how a climate denier finally convinced me, once and for all, that climate science was on pretty safe ground."
The problem of the test is, it is possible to be confident that a scientific statement is wrong. A scientific hypothesis should be falsifiable. One should mainly not be too confident that one is right. Making of positive claim about reality is always risky.
For example, you can be confident that someone cannot claim that all of climate science is a sham after studying temperature changes in the distant past ("hockey stick"). That is a logical fallacy. The theory of global warming is not only based on the hockey stick, but also on our physical understanding of radiative transfer and the atmosphere and on our understanding of the atmospheres of the other planets and on global climate models. Science is confident it is warming not only because of the hockey stick, but also because of historical temperature measurements, other changes in the climate (precipitation, circulation), changes in ecosystems, warming of lakes and rivers, decreases of the snow cover and so on.
So in this case, the mitigation sceptic is talking nonsense, but theoretically it would have been possible that he was rightly confident that the maths was wrong. Just like I am confident that many of the claims on WUWT & Co on homogenization are wrong. That does not mean that I am confident the data is flawless, but just that you should not get your science from WUWT & Co.
Three years ago Anthony Watts, host of WUWT, called a conference contribution a peer reviewed article. I am confident that that is wrong. The abstract claimed without arguments that half of the homogenization should go up and half should go down. I am confident that that assumption is wrong. The conference contribution offered a span of possible values. Anthony Watts put the worst extreme in his headline. That is wrong. Now after three years with no follow-up it is clear that the authors accept that the conference contribution contained serious problems.
Anthony Watts corrected his post and admitted that the conference contribution was not a peer reviewed article. This is rare and the other errors remain. Next to overconfidence, not admitting to be wrong is also common among mitigation sceptics. Anyone who is truly sceptical and follows the climate "debate", please pay attention, when a mitigation sceptic loses an argument, he ignores this and moves to the next try. This is so common that one of my main tips on debating mitigation sceptics is to make sure you stay on topic and point out to the reader when the mitigation sceptic tries to change the topic. (And the reader is the person you want to convince.)
Not being able to admit mistakes is human, but also a sure way to end up with a completely wrong view of the world. That may explain this tendency of the mitigation sceptics. It is also possible that the mitigation sceptic knows from the start that his argument is bogus, but hopes to confuse the public. Then it is better not to admit to be wrong, because then this mitigation sceptic runs the risk of being reminded of that the next time he tries his scam.
Less common, but also important is the second order nut test for people who promote obvious nonsense, claim not to know who is right to give the impression that there is more uncertainty than there really is. Someone claiming to have doubts about a large number of solid results is a clear warning light. One the above mitigation sceptic is apparently also guilty of ("chronic critic"). It needs a lot of expertise to find problems, it is not likely that some average bloke or even some average scientist pulls this off.
Not wanting to look like a nut, I make an explicit effort to not only talk about what we are sure about (it is warming, it is us, it will continue if we keep on using fossil fuels), but also what we are nor sure about (the temperature change up to the last tenth of a degree). To distinguish myself from the nuts, I try to apologize even when this is not strictly necessary. In this case even when the nut test is quite useful and the above conclusions were probably right.
Related readingScience journalist Dan Vergano wrote a nice article article on his journey from conservative Catholic climate "sceptic" to someone who accepts the science (including the nut test): How I Came To Jesus On Global Warming.
The three year old conference contribution: Investigation of methods for hydroclimatic data homogenization.
Anthony Watts calls inhomogeneity in his web traffic a success.
Some ideas on how to talk with mitigation sceptics and some stories of people who managed to find their way back to reality.
Falsifiable and falsification in science. Falsifiable is essential. Falsification not that important nor straightforward.