The note by Nafeez Ahmed on the "Nasa-funded paper" (a term that went viral) on societal collapse was followed by a heated debate. In a previous post of mine, I noted how we were seeing again the debate that took place after the publication of the first "The Limits to Growth" study in 1972. Indeed, it is the same debate, complete with the mistakes and misinterpretations of that time.
Let me examine the rebuttal to Ahmed's post published by Keith Kloor. In it, Kloor seeks support for his arguments with a number of external opinion. For instance, he cites Mark Sagoff as stating
"At one point, I skimmed the article yesterday and saw that it was the Club of Rome all over again — the computer that cried wolf. [...] There is nothing here [in the paper] that was not presented in the 1960s and 1970s by Paul Ehrlich and other “Cassandras” as they called themselves. Their views, repeated in this [Guardian] article and study, have been completely discredited. [...] Nobody learns anything or bothers to try."
I would venture to say that, before criticizing a paper, one should examine it a little more in depth than simply "skimming" it. Indeed, here Sagoff justifies his stance simply on the basis of old legends that say that the views of the Club of Rome "have been completely discredited."
It is curious to note that the term "Club of Rome" is still so often automatically associated with the idea that "The Limits to Growth" study was completely discredited. It is not so, and there is a whole literature which shows how the results of the study turned out to be valid to describe the present situation (*). The "Computer that cried wolf" is just one of the many legends that went viral and still infect cyberspace. Indeed, Sagoff's statement "Nobody learns anything or bothers to try" better describes the critics of the study than its supporters.
Another author that Kloor cites in support of his thesis is Vaclav Smil. Kloor doesn't report what Smil told to him, but we can find Smil's opinion on this matter in a paper that appeared in "Population and Development Review", in 2005, where he criticizes "The Limits to Growth" mainly on the basis of statements of disbelief and on the fact that the model is too simple. To give you some idea of the tone and the substance of Smil's arguments, let me consider the following sentence:
[In the model] Declining arable land still keeps lowering food production, while in the real world there is, globally, an obscene surplus of food as epidemics of obesity affect more and more countries.
Can you see the problem, here? Smil mistakes a parameter for the model. "Arable land" is a parameter of the model. It is NOT the model. And, of course, declining arable land as a parameter has the effect of lowering food production: how could it be otherwise? But the model has other parameters related to food production: energy, fertilizers, technology and more. The result is that food production can keep increasing despite declining arable land. So, the model correctly describes the behavior of food production in the real world (alas, up to now; what will happen in the future is all to be seen).
It is almost incredible how easy it is to make this kind of mistake even for competent people, such as Vaclav Smil. But it happens all the time: it is the same mistake that William Nordhaus made back in 1973 when he criticized a model similar to the one used for the Limits to Growth. He took a single equation out of the model and showed that the equation - alone - couldn't reproduce the behavior of the real world. Of course: cut off a leg from a frog. Note that the leg, alone, can't jump. Then conclude that frogs can't jump. Impeccable logic. (see "The Limits to Growth Revisited" for details about this story).
There is much more to be said about the "Nasa-funded study" and it is perfectly possible to criticize it for sound reasons. Unfortunately, however, the "debates" on this subject seem to be mainly about showing the power of legends in affecting human minds. And we will see over and over the same position: since we don't like the results of the model, then the model can't be true. We never seem to be able to remember that models are just tools, and never prophecies.
(*)
"The Limits to Growth Revisited"
"Looking back on the limits to growth"
"The World model controversy"
"Revisiting the limits to growth"
.... and many more
