Why 'The Population Bomb' Bombed

The Green Revolution defused the threat of mass starvation.

Wrong or just early?

Photographer: James D. Wilson/Getty Image

It is difficult to make predictions, especially about the future.

Any aphorism that gets attributed to both Niels Bohr and Yogi Berra (as well as Samuel Goldwyn, Mark Twain and others), has got to have something going for it. It is difficult to make predictions about the future.

That alone seems to be a good reason to cut some slack for Paul Ehrlich, whose 1968 bestseller “The Population Bomb” forecast the imminent breakdown of the world’s ability to feed itself.

Not that Ehrlich himself makes this easy to do. In a just-released New York Times mini-documentary on the book and its aftermath, the now-83-year-old Stanford biologist says insufferable things like, “One of the things that people don’t understand is that timing to an ecologist is very, very different from timing to an average person.” Uh, then why did you write a book clearly aimed at average people that confidently predicted that in the 1970s hundreds of millions would die of famine? “I expressed more certainty because I was trying to bring people to get something done.” (In that vein he also co-founded the activist group Zero Population Growth, rechristened in 2002 as Population Connection.)

Still, I figured I’d give the book itself a chance. I’ve had a copy for years, and thanks to a recent book-sorting project I was able to find it in a matter of seconds this morning. Because it’s not very long, I was able to read it in an hour or two. And I have to say it surprised me.

First of all, half of Ehrlich’s prediction came true. He forecast in the book that global population, about 3.5 billion at the time, would double by 2005. He was only six years off on that -- world population hit 7 billion in 2011 -- which I figure counts as getting it right.

What Ehrlich famously got wrong was the planet’s carrying capacity. Sure, global population doubled. But thanks to the Green Revolution, per-acre grain yields went up much faster than that. The inflection point in global agricultural productivity, in fact, came just as Ehrlich was finishing his book.

Here’s the interesting thing, though -- Ehrlich was well aware that this was a possibility. New rice, wheat and corn varieties, he wrote in 1968, “have the potential for at least doubling yields under proper growing conditions.” They were, he concluded, the world’s best shot at averting mass famine. But while he was “hopeful” about the prospects for an “agricultural revolution,” there were all kinds of things that could go wrong, so he didn’t think anybody should bank on it.

That’s a pretty reasonable position. Productivity bursts, in agriculture as in other economic endeavors, have always been hard to predict. You wouldn’t want to take the earliest signs of one as evidence that you could stop worrying.

The same goes for almost all the environmental concerns voiced by Ehrlich in the book. Sure, he’s awfully gloomy about the U.S.’s smoggy skies and befouled waterways. But the environmental laws that began to remedy these problems for the most part hadn’t been enacted yet in 1968 -- and I find it a little hard to fault a guy for not anticipating wise, forward-looking moves by Congress. All in all, he comes across as a reasonable pessimist about the environment.

It was only when he got around to people and their reproductive rates that Ehrlich went over the edge -- those sections of his book sound misanthropic and scarily authoritarian to modern ears. “Population control, of course, is the only solution to population growth,” Ehrlich wrote. Slowing population growth in a few developed countries was nothing more than “short-term fluctuations” in apparently inexorable demographic trends. He advocated luxury taxes on diapers and cribs in the U.S., and endorsed forced sterilization of fathers of three or more children in India, adding, “Coercion? Perhaps, but coercion in a good cause.” He did at least stop short at eugenics, saying that we knew way too little about “genetic quality” and who possessed it to try to build population control programs around it.

Still, population growth was the part of the equation that Ehrlich got right. Sure, he completely dismissed the possibility that populations might start shrinking in the absence of government coercion -- exactly what has since happened in Japan, Germany and a few other countries. But those population declines have been swamped by increases elsewhere, so overall Ehrlich still got it right. All he was doing was drawing a trend line forward, but that did the trick.

What if anything does this teach us about our current global population situation? My sense is that few are counting on another Green-Revolution-style leap in agricultural productivity, although sub-Saharan Africa -- which largely missed out on the last Green Revolution -- might still have potential for big gains. Yet there is little of the population angst that prevailed in the 1960s and 1970s, largely because of a widespread belief that global population will plateau this century as country after country becomes wealthier and birth rates plummet.

You can see this from the United Nations’ latest population projections -- if high fertility rates continue, global population will pass 10 billion in 27 years and 15 billion in 73 years. It is only if the trend toward having fewer children continues and spreads to many more countries that population will stabilize or even drop.

population correct

The idea, then, is that the spread of affluence will solve the world’s population dilemma. Instead of coercion, we can rely on college tuition and expensive urban real estate to keep fertility rates in check. This is a ton more attractive than Paul Ehrlich’s prediction of either chaos or government-imposed population control. Will it turn to out to be any more accurate? Not sure. Predicting is hard. Especially about the future.

This column does not necessarily reflect the opinion of Bloomberg View's editorial board or Bloomberg LP, its owners and investors.

    To contact the author on this story:
    Justin Fox at justinfox@bloomberg.net

    To contact the editor on this story:
    James Greiff at jgreiff@bloomberg.net

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