By John Feeney:
Update #2: For a correct, non-deceptive comparison of population growth and consumption growth, click here for a recent example from former AAAS president, John Holdren.
Sometimes I read something, such as a recent article by George Monbiot (whose work I’ve often admired, by the way), and realize the basics bear repeating.
Environmental and other writers speak often about resource consumption. On occasion they write something about population growth. Once in a while they tackle the whole package – population and consumption. When they do, they often make a simple error and come to the wrong conclusion.
Typically, it goes something like this: “Yes, population growth is a problem. But growth in consumption is occurring faster, so it’s an even bigger problem.”
Total resource consumption (of one or all resources) is the product of population size and average per person consumption. Naturally, we would expect the growth of the product to exceed that of either of two growing factors driving it! As an example, 2*2=4 and 4*4=16. Here the factors have increased by the same amount; they’ve doubled. But the product has quadrupled. A factor and the product are not comparable elements.
The more appropriate comparison is between the factors, population and per person consumption. There the data tell us the differences are not so pronounced, and it’s clear we cannot prioritize and say it is more urgent to address one than the other.
It’s the same error if you see a comparison suggesting economic growth far outweighs population growth as an environmental problem. Economic growth can, after all, be understood (PDF) as closely overlapping total consumption. It’s held to be driven by population multiplied by per person consumption. George Monbiot certainly sees it that way as he equates economic growth and total consumption in his fourth paragraph.
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