In this Sunday's Washington Post, George Will excoriates the 1972 book, Limits to Growth (LtG) for making failed forecasts that we would run out of various nonrenewable natural resources by now, bringing up Paul Ehrlich's losing bet with the late Julian Simon about metals prices in the 1980s. He then argues that we can therefore pay no attention to anything anybody was worried about at the recent Rio Earth Summit, and, btw, that Obama's current science adviser, John Holdren, was once an adviser of Paul Ehrlich's, eeeeek!
First we should recognize that LtG was seriously flawed, and from Day One its problems were noted by such figures as Robert Solow and Joseph Stiglitz. The main flaw they pointed out, also argued by Simon, was the over-aggregation in the model: five variables at the global level, population, food, natural resources, industrial production, and pollution. Indeed, the model simply ignored the sorts of microeconomic adjustments that can occur for individual resources, such as mercury (demand for which has fallen 98% since 1972).
Second, they made their forecasts of running out of specific resources by simply looking at "measured reserves" and seeing how long those would last at then current usage rates. The problem with this, which they really should have known, is that those reserves are not at all estimates of how much of any resource there really is. They are what are known with high certainty to be there and also can be extracted profitably at current prices with existing technology. In fact, for most of these resources, measured reserves have risen over time.
But, this does not get Will off the hook, as this is all old news, and he has not caught up. Sure, Paul Ehrlich lost his bet with Simon in the 1980s, but he would have won the same bet if it had been made in 2000. Furthermore, at Rio and elsewhere it is now understood that the real problems are not that we are going to run of tin and mercury, but that we may deplete our fisheries and destroy our forests and croplands through such things as climate change. This latter was not discussed at all in LtG, and Will conveniently ignores it in his column. Amusingly, he cites Bjorn Lomborg in dumping on LtG about all those metals, but fails to mention that Lomborg has changed his position about climate change from it not being that big of a problem to that it is a serious problem.
Yes, the Limits to Growth presented a deeply flawed model that in retrospect looks pretty silly. But beating it over the head as a dead horse is seriously irrelevant to the current problems that we face. Unfortunately, this sort of approach to arguing is all too typical of Will.