Climate Change – Me, Trump, SWP, The Narrative and Thomas Bayes

On May 23, this letter appeared in the Australian Financial Review:

Can we risk denying climate science?

On March 9 this year Scott Pruitt, the new head of the US Environmental Protection Agency, said there was “tremendous disagreement” about the impact of carbon dioxide emissions on global warming.

The Australian Academy of Science (like pretty much every scientific institution in the world) doesn’t agree with Mr Pruitt and says on its website that: “… human activities … have sharply increased greenhouse gas concentrations … these gases have a warming effect … warming has been observed … continued reliance on fossil fuels would lead to greater impacts in the future … This understanding represents the work of thousands of experts …” You can see the details by googling “AAS and climate change”.

US geologist James Powell identified some 33,700 peer-reviewed climate scientists of whom some 9oper cent agree with the AAS.

So where does this view of “tremendous disagreement” come from? What people such as Mr Pruitt are often referring to is the online Global Warming Petition Project by which 31,487 scientists joined a petition to the US government that includes a statement that: “There is no convincing scientific evidence that human release of carbon dioxide, methane or other greenhouse gases is causing or will, in the foreseeable future, cause catastrophic heating of the Earth’s atmosphere and destruction of the Earth’s climate.” (See the website by googling “global warming petition”.)

So doesn’t 90per cent of 33,700 saying “yes” and 31,487 saying “no” justify a claim of “tremendous disagreement”? Not if you look more closely.

First, the 31,487 is out of a pool of some 11.5million relevant scientists in the US, according to the 2009 census. So not a big take-up.

Second, you don’t have to be a climate scientist to sign. All you need is a basic science degree, no matter in what discipline – even “general science” is enough.

Third, of the 31,487 signatories, just 39 claim to have scientific experience in climatology.

Fourth, the names, according to the website, were gathered between 1998 and 2007. So seven years without a new signatory?

Maybe there were more signatories after 2007 but in April 2013, when I looked at the website for a talk I was giving, the number of signatories was the same – 31,487 – and the number claiming climatology as their area of science was – you guessed it – 39!

Everyone has the right to an opinion. But who wants to punt their children’s and grandchildren’s future on the opinions of anyone other than the vast majority of peer-reviewed climate scientists and scientific institutions like our own highly respected Australian Academy of Science? Not me.

Jim Main

Cootamundra, NSW

I penned this reply soon after, and sent it in to the newspaper:

Dear Sir, 

Jim Main [Letters, May 24, 2017] makes a strong case in favour of taking action against carbon dioxide emissions. But his case is not unanswerable.

His argument relies heavily on the pronouncements of experts. However, arguments from authority arent really applicable in this field now. For thirty years, the public has heard dire warnings about climate change which have never come to pass. This is probably because the models used by the experts have been shown to be not reliable, with a heavy bias towards over-estimating the temperature and climate impacts of carbon dioxide emissions.

But even if the models had been correct, we would still be left with the question of how we should respond. Carbon abatement on the scale necessary to reduce emissions significantly is tremendously expensive, and even a successful abatement programme would only delay by a few years the forecast rise in temperatures. This would be a heavy cost to impose on society for negligible corresponding benefit.

Even then, should our abatement programmes succeed, we would then face the problem that the earth might continue warming anyway, due to influences on temperature other than carbon dioxide.

Given all this, the best response is, I think, to continue growing our economies as quickly as possible, so as to generate the resources needed to allow adaptation to any and all climate changes, regardless of their cause. After all, another ice-age glaciation is all but inevitable and that really will be transformational climate change.

My letter wasn’t published.

I thought this piece on Trump’s withdrawing from the Paris Climate Accord came closest to my own thoughts.

For the purposes of our interests, it seems to me that much of the misunderstanding and hysteria over global warming, on the part of the alarmists, is a failure of Bayesian updating. Since the warming scare began, around three decades ago, and the science has advanced tremendously in that time. From what I can see, what started off as a terrifying prognosis has turned out to have been grossly exaggerated: the early models misunderstood the interactions between carbon dioxide and temperature, and so greatly overstated the effects of ongoing global warming on the climate. In fact, what we actually discovered, through the ice core samples, is that carbon dioxide levels in the atmosphere actually lag temperature increases, rather than lead them. There is also the question of logarithmic absorption and saturation, and the estimates of costs to GDP of both no action and action, which show the costs of action to be many orders of magnitude greater than taking no action and just adapting.

All of this information is significant for our beliefs about global warming, and what to do about it. But the alarmists, for whatever reason, haven’t updated any of their beliefs to account for it. We can classify this error partly as slothful induction caused by an unwillingness to acknowledge unwelcome truths, and partly as Begging the Question in Induction [more the error of non-observation, but there may be some of the error of mal-observation in there as well].

A question for us to think about is: what is the difference between slothful induction and the error of non-observation?



About Stebbing Heuer

A person interested in exploring human perception, reasoning, judgement and deciding, and in promoting clear, effective thinking and the making of good decisions.
This entry was posted in Epistemic Rationality, Motivated Reasoning, Narrative and Taboo, The Mind & Society. Bookmark the permalink.

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