Our Overpopulation Arugments: A Straw Man?

by Jay Johansen
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We recently received an email claiming that, well, let me give you the writer's own words:

... Your position against overpopulation, is what is known as a strawman, that is you are building a case against the incorrect overpopulation scenario. The fact is you are correct that the planet can sustain our current population, however, at current growth rates 96% of the livable land shall be used up by humans in approximately 100 years.

I will explain:

The history of the TRUE overpopulation statement started with a Canadian Dr. David Suzuki, who back in the early 1980's made the observation based on the known effects of sustained population growth in a closed environment. ... In the test tube, a single yeast is placed it divides, and continues to divide, the yeast take up more and more room in the tube. [Eventually it takes up 6%] ... The yeast culture will double every 4 hours therefore in 4 generations or 16 hours they will fill 96% of the tube.

When Dr. Suzuki presented this in the early 80's humans occupied 6% of the arable land on the planet we are at 8% now and double the human population every 30 years. ... At current growth rates 96% of the livable land shall be used up by humans in approximately 100 years. ...

To which I make this reply:

As I understand you, you are saying that we are attacking a strawman by claiming that people who warn of overpopulation say that the world is overpopulated now, while in reality, you say, they claim not that it is overpopulated now but rather that it will be overpopulated in 50 to 100 years.

While I do not doubt that some overpopulationists (if I may use this as a short-hand term) state the problem this way, surely you cannot mean that this is what all overpopulationists say. Paul Ehrlich is surely one of the best known overpopulationists in the U.S. In his 1990 book, The Population Explosion, the very first paragraph states, "In 1968, The Population Bomb [an earlier book of his] warned of impending disaster if the population explosion was not brought under control. Then the fuse was burning; now the population bomb has detonated. Since 1968, at least 200 million people -- mostly children -- have perished needlessly of hunger and hunger-related diseases ..." etc. Clearly Mr Ehrlich believes that the crisis is here now, not 100 years away. On the Web, "overpopulation.org"'s main page says, "Overpopulation is a serious problem getting worse every year". Again, they clearly think it is a problem now and not just a potential problem for the future.

If what you mean is that you agree that they are wrong, than surely you cannot fault us for saying so!

We do indeed acknowledge that this is not the position of all overpopulationists. I routinely point out these two distinct views in my lectures. I don't recall any place where we specifically spell this out on the Web site, but for example in our article The Food Crisis, we say "Population control activists routinely argue that the world cannot continue to support an ver-increasing population. Resources are finite, and they are starting to run out, or will run out soon." Note we acknowledge the distinction between the two positions.

Your statement that Dr. Suzuki started the "TRUE overpopulation" movement is surely rather parochial. People have been talking about overpopulation since at least Thomas Malthus in the 18th century. If you think they were wrong but Dr. Suzuki is right, I'm certainly happy to discuss that issue, but I really fail to see how you can fault us for rebutting ideas which have been made by many people repeatedly for at least two hundred years, which continue to be made by many influential people in the present, and which you yourself agree are incorrect. So I must in all humility reject your criticism of us in this regard.

But to deal with the substantive issue that you raise:

I don't know where you got 8% as your "present" figure. I'm not saying it's wrong, it's just hard to measure and depends a lot on definitions. Actually my sources give somewhat higher figures. One I often quote is a UN study of a few years back that says that people are presently farming about 11% of the world's total land. Farming is probably the major human use of land, cities and roads and mines take a pretty small amount of space compared to farmland, so that should be pretty close to the total. But hey, I'll use your figures, as they're even less favorable to the overpopulation argument than the ones I've been using. :-)

But how do you get from there to concluding that we will be using virtually 100% of the world's land in 50 to 100 years? Right now world population is growing at something like 1.5% per year. At that rate, in 50 years population will be somewhat over double what it is now. In 100 years, it will be a little under 4 1/2 times what it is now. Even if we assume the rate goes up to 2% for 100 years, the population would then reach about 7 times what it is now in 100 years. 7 times 8% is still only 56%. Or if you want to use the UN's 11%, 7 times 11% is 77%. Either way it's well under 96%. Of course it's still pretty high and if I really believed that was going to happen I might be concerned. But in fact growth rates are declining, and most demographers say that if present trends continue, world population will stabilize at around 9 billion by about 2030. Even Al Gore -- a staunch overpopulationist himself -- says in his book Earth in the Balance that "Although until recently experts were predicting that population would stabilize at 10 billion sometime in the next century, they now say the total could reach 14 billion or even higher before leveling off". (p 308) In context, he's clearly trying to stress the grave nature of the crisis, so we have to take this as the worst case. And so the worst case appears to be that world population might triple before leveling off. Assuming land use increased proportionately to population, that would put us using 24 to 33% of the world's land (depending on whether you start with your 8% or the UN's 11%).

And I can assure you that land use will not increase proportionate to population. The major use of land is farming, and historically we are not seeing more and more land going to farming. Quite the contrary, in the U.S. the amount of farmland has been steadily decreasing as farmers become more efficient faster than population can grow. I don't have figures on the rest of the world, perhaps in underdeveloped countries this is not the case, but as technology diffuses they should see the same results.

I've been accepting (and even raising) your 8% figure, but if we read your analogy closely, it is, in fact, wildly inflated. With the yeast culture, you are talking about how much space they actually fill with their bodies. Humans do not actually occupy anywhere near 8% of the world's land area. If we figure a round 6 billion people in the world today, if each one takes about 4 square feet to stand comfortably without rubbing shoulders, the total standing room required for them all is 24 billion square feet or 860 square miles. The world has about 53 million square miles of land (excluding Antartica), so in terms of standing room we're only using about .0016% of the world's land area.

Of course we use land for many purpose other than just to stand on it, like farms and mines and roads. But it does not at all follow that as population grows, that uses other than standing room must increase proportionately. With advancing technology we can make more efficient use of land.

It is also incorrect to say that human population is doubling every 30 years. Population growth peaked at a point where, if it had continued indefinately, the population could have doubled in about 30 years. But it's well down from that now. The figures I've seen recently are 1.5% to 1.7% depending on whose figures you take, which would give a doubling time of more like 45 years. And that's continuing to fall, as noted above.

Thus in real life, if present trends continue, 100 years from now humans might be using somewhere between a quarter and a third of the Earth's land surface, if there are absolutely no improvements in agricultural productivity between now and then. Based on past experience, the more likely scenario is that agricultural productivity will continue to improve faster than the population grows, so it is likley we will be using only marginally more land in 100 years than we use now.


A couple of final side notes. These aren't really relevant to the overpopulation issue, but rather are comments about debating in general.

The original email ended with two statements of a sort I have heard numerous times, and which I find to be unproductive in debates.

First, the writer said, "This model is agreed to by most of the scientific community world wide." In this particular case, I don't know of any surveys on the subject, but it is certainly not what one routinely hears from demographers, as noted in the main text above. But even if it was true, the obvious answer is, So what? Scientific truth is not determined by taking a vote, but by experimentation and observation. If it is really true that most scientists believe some theory, it may be because that is where the evidence really leads, or it may be because they are fallible human beings and have been swayed by political or social biases, or maybe they've never really studied the subject and just took the word of a few not-necessarily-infallible people who claimed to know. If they were convinced by the evidence, show me the evidence and not the poll results. If they were convinced by something else, than I simply don't care.

Second, the writer concluded with this statement: "Please update your web site to reflect the correct overpopulation position." Over the years we have received a number of emails which end with a similar comment. I don't wish to be rude, but let me give a word of friendly advice to anyone planning to engage in debate with us or anyone else: Skip the smug and arrogant remarks about expecting your opponent to retract everything they've ever said just because you told them they were wrong. Especially when you haven't even heard their reply to your arguments yet. If someone has taken the time to research and write a series of articles on a subject, it is likely that they have already heard arguments similar to any you might make, and they weren't convinced by them the first time around. You are much more likely to change someone's mind if you keep your comments polite and at least reasonably humble.


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Posted 10 Sep 2000.

Copyright ©1999 by Jay Johansen
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