Can climatology ever be considered a science? My favourite Richard Feynman quote.

You cannot prove a vague theory wrong. If the guess that you make is poorly expressed and the method you have for computing the consequences is a little vague then ….. you see that the theory is good as it can’t be proved wrong. If the process of computing the consequences is indefinite, then with a little skill any experimental result can be made to look like an expected consequence.

I would maintain that by its nature climatology will always be a vague theory. Climate consists of an infinite number of interrelationships that can only be loosely modelled by empirical generalisations. These can only ever be imperfectly measured, although that is improving both in scope and period of observations. Tweaking the models can always produce a desired outcome. In this sense climatology is never going to be a science way that physics and chemistry have become. But this does not mean that climatology cannot become more scientific. A step forward might be to classify empirical statements according to the part of the global warming theory they support, and the empirical content of those statements.

Catastrophic Anthropogenic Global Warming (CAGW) is a subset of AGW. The other elements of AGW are trivial, or positive. I would also include the benign impacts of aerosols in reducing the warming impacts. So AGW’ is not an empty set.

AGW is a subset of GW, where GW is the hypothesis that an increase in greenhouse gas levels will cause temperatures to rise. There could be natural causes of the rise in greenhouse gases as well, so GW’ is not an empty set.

GW is a subset of Climate Change CC. That is all causes of changing climate, both known and unknown, including entirely random causes.

In summary

CAGW ⊂ AGW ⊂ GW ⊂ CC

Or diagrammatically the sets can be represented by a series of concentric rings.

To become more scientific, climatology as an academic discipline should be moving on two complementary fronts. Firstly, through generating clearer empirical confirmations, as against banal statements or conditional forecasts. Secondly, for the statements to become more unambiguous in being ascribable solely to the CAGW hypothesis in particular rather being just as easily be ascribed to vague and causeless climate change in general. These twin aims are shown in the diagram below, where the discipline should be aiming in the direction of the red progressing arrow towards science, rather the green degenerating arrow.

Nullis in verba on a recent Bishop Hill discussion forum rightly points out the statement

“you acknowledge that scientists predicted warming. And warming is what we observed”

commits the fallacy of “confirming the consequent”.

If your definition of climate change is loose enough, the observed rise could be a member the CC set. But to infer it is not part of GW’ (outside of the GW set) requires more empirical content. As Nullis has shown in his tightly worded comment to prove this is impossible. But the greater empirical content will give more confidence that the scientists did not just strike lucky. Two years ago Roy Spencer did attempt just that. From 73 climate models the prediction was that between 1979 and 2012 average global temperatures would rise by between 0.3 and 1.5C, with an average estimate of 0.8C. Most were within the 0.6 to 1.2C, so any actual rise in that range, which is pretty unusual historically, would be a fairly strong confirmation of a significant AGW impact. The actual satellite and weather balloon data showed a rise of about 0.2C. The scientists got it wrong on the basis of their current models. At a minimum the models are running too hot, at a minimum failing to confirm the CAGW hypothesis.

By more clearly specifying the empirical content of statements the scope of alternative explanations is narrowed. In this case we have an explanation for someone using a more banal statement.

I would contend that to obtain confirmation of CAGW requires a combination of the warming and the adverse consequences. So even if the hurricanes had got worse after Katrina in 2005, with zero warming on its own it is just that an observation climate has changed. But together they form a more empirically rich story that is explained by CAGW theory. Still better is a number of catastrophic consequences.

In the next post I shall show some further examples of the discipline moving in the direction of degenerating climatology.

Kevin Marshall