Naomi Oreskes, a renowned and politically engaged Harvard historian, recently published something curious — and inadvertently revealing — in Scientific American. “We ought to have a plan for slowing the destructive surge in human population,” she wrote. “But we don't.”
Oreskes blamed this failure on “Cornucopian” thinking, a school of thought that came to prominence in the 1980s, when it was led by the economist Julian Simon and the physicist and strategist Herman Kahn. Cornucopianism said population growth was not a threat at all, no matter how rapidly or steadily human populations grew: More people doesn’t merely mean more mouths to feed; it means more hands for work and, more importantly, more brains for invention. Thanks to human ingenuity, the Cornucopians argued, there was no limit to how much the human population could comfortably grow. Literally. “We now have in our hands—really, in our libraries—the technology to feed, clothe, and supply energy to an ever-growing population for the next seven billion years,” Simon wrote with characteristic bombast.
The extreme claims of Simon et al were themselves a reaction to equally extreme claims by Malthusians like Paul Ehrlich, who insisted in the 1960s that populations had already grown much too large to sustain themselves. In the decade ahead, they said, it was inevitable that the world would suffer catastrophic environmental degradation and nation-collapsing famines.
The inevitable turned out to be quite evitable and the failure of Malthusians’ dire predictions in the 1970s gave prominence to the Cornucopians in the 1980s.
But now — in 2023 — Oreskes writes that we need to finally get serious about curtailing population growth in order to stave off environmental disaster.
…there are reasonable ways to slow growth. For one, women and girls should have greater access to education. Studies show opportunities to learn are an effective means to slow population increases. Focusing on that goal—which has many other benefits—most likely will produce the fresh energy and ideas that we need across the globe. It is much more realistic than fatuously assuring listeners that in the future, somehow, all will be well.
What’s strange about Oreskes’s article is that it could have been written, word for word, in 1987.
That’s also what is inadvertently revealing.
I’ve written a great deal about demography over the past twenty years and I know from feedback that both Malthusian and Cornucopian thinking is alive and well, among activists and think tanks but also the public at large. Does human population growth need to be curtailed or reversed? Can our numbers rise forever without sacrificing health, prosperity, and the environment? Mention demography and lots of people will speak their minds — and reveal that what is in their minds is the world as it was in the 1980s, not today.
With the help of the wonderful Our World In Data, let me walk you through the demographic facts. (Note that all the graphs below are interactive on the Our World In Data website, so you can add or subtract countries and regions. And there are so many subjects covered. I spend hours there, clicking on this and that. It’s geeky fun.)
First, global population growth. It is indeed up.
Way, way up.
The human brain is an extrapolation machine and it’s a struggle to look at a chart like that and not see that line continue to soar far into the future. What will it get to? Maybe 10 or 11 billion people by 2050? How about 15 billion by 2100? The Julian Simons of the world may be fine with that. But hardcore Corucopians aside, it’s difficult for people to contemplate a future like that without hyperventilating into a paper bag.
But here’s the tricky thing about demography: Like tectonic plates, it’s powerful but slow. What happens today shapes the demographic facts many, many decades from now. Or to put that the other way around: The numbers we see now were largely determined many, many decades ago.
Population is the ultimate lagging indicator. We need to look at the leading indicators.
Human population is the product of two things: births and deaths.
That giant rise in the global population? It didn't happen because people suddenly started having far more babies. It happened because far more of the babies people had were surviving into adulthood than ever before, and adults lived longer than ever before: When people stop dying as much, you get more people.
It works the other way, too. Reduce the birth rates and, other things being equal, you get fewer people. And birth rates (or “fertility rates”) have been changing just as dramatically as death rates.
See where the rate is now? A little above two. That’s extremely significant. For a population to replace itself — that is, merely to avoid population decline — the average woman must have two children. And to account for the occasional salmon in the ocean who never makes it back to spawn in the river, that number needs to be nudged up a little. Hence, 2.1 children per woman is considered the “replacement rate.”
That’s almost where the world is. Now.
This is why it’s so weird to hear Malthusians rail against soaring populations while Cornucopians insist populations can soar forever. Global population is going to stop soaring no matter what anyone thinks or wants. Malthusians arguing with Cornucopians about whether the human population can grow forever is as dated and irrelevant today as Miami Vice.
Or perhaps you are thinking that the global number fertility number masks the underlying reality — rich countries may be below the replacement level but all those poor countries are still churning out hordes of babies.
So let’s break this out.
Here are the fertility rates in leading developed countries — aka “the rich.”
They are indeed low. In fact, they are all substantially below the replacement rate.
Now here are the fertility rates in the major developing countries — the so-called “poor” countries — plus the US for comparison.
As the late, great Hans Rosling so memorably illustrated, mentally dividing the world between rich countries and poor countries ceased to make sense long ago.
The “population explosion” of the 20th century was the function of what demographers call the “demographic transition.”
For most of human history, people had high death rates and high fertility rates. When high death rates started falling, the high fertility rates sent populations soaring. But then the fertility rates fell, too. To be modern, in a demographic sense, is to have both low death rates and low fertility rates. And when you have that, populations do not explode. They lie flat. Or they decline.
The vast majority of the world is either well along in that transition or has completed it.
In fact, large numbers of countries have been well below “replacement level” fertility for decades. In some (the US, Canada, Australia, Spain, etc.) immigration has masked that reality and kept populations rising, if slowly. In others (Japan, Italy, Poland, etc.) the math is on full display and the overall population is falling. Want to buy a lovely vacation home in the countryside but don’t have much money? Go to the rural regions of these countries. There are scads of unbelievably cheap houses for sale.
Lots more countries are at the tipping point of absolute population decline, or soon will be. South Korea recently recorded its first population decrease and given how disastrously low its fertility rate is — 0.92 — its coming decline will more accurately be described as a plunge. Even China will soon join the club. Mao once shrugged at the prospect of nuclear war on the grounds that if China lost a hundred million citizens the Chinese people would just have more children and replace them. Very soon, China will lose far more than a hundred million people without war. And they won’t be replaced.
United Nations projections have global population peaking in 2100, or a little sooner, but past UN projections have tended to exaggerate population growth and some observers think the peak will come decades earlier. One of the UN’s projections, which assumes lower-than-expected fertility, has global population peaking at just under nine billion in mid-century and falling to seven billion by 2100. That’s a net population decline from present of one billion people.
But in any event, barring an unimaginable change of cultures and lifestyles around the world, the peak is coming. And for much of the world, it will come a lot sooner than most people imagine.
This chart shows population growth from 1950 to today, plus the projections to 2100 made by the United Nations using their medium fertility estimate.
In that chart, India’s peak population declines by a tenth, Brazil’s and Germany’s by a fifth, China’s by almost half, and South Korea’s by more than half.
Does it look like what the world urgently needs right now is “a plan for slowing the destructive surge” in the human population?
Of course no reasonable person would disagree with Naomi Oreskes that boosting education levels, particularly for girls, is a wise policy with loads of positive benefits.
But, again, this isn’t 1987.
Education rates have soared around the world over the past half century. And while significant gender inequality continues in some regions, there have been enormous improvements everywhere.
All that said, there is one word Oreskes didn’t mention in her article which I must. It is “Africa.”
Africa remains a demographic outlier, with much of the continent lagging behind in the demographic transition. You can see that vividly here.
Because of this, regional shares of the global population are likely to shift considerably.
The world needs Africa to progress and prosper because, in the future, much of the world will be Africa. So if someone wants to argue that the world should be doing more to help boost education in Africa, particularly for girls, I will happily nod along. (A big boost in African agricultural productivity is also urgently needed.) But it’s important to keep this in perspective. Africa may not have advanced nearly as much as other regions, but it has made considerable progress. In many countries, education rates are way up while both death rates and fertility rates have fallen substantially.
I am neither a Malthusian nor a Cornucopian. Such single-lens visions have little appeal for me, whatever it is they see.
I simply think we must grasp and respond to the facts on the ground, as best we can, not the impressions in our heads. Too many of us are stuck in the past. The reality of human population is not what it was in the 20th century.
This is not 1987. Let’s move on.
UPDATE: Reader Max More shared an excellent comment below. And he’s absolutely right about another chart from Our World In Data I should have included. Here it is
Great article! I think that a big problem about the future demographics is the % of the world population that will be elderly could increase substantially. This will deplete retirement plans and healthcare plans if there are not enough young people to replace retirees in the workforce.
This is a good article. For your growth curves, some people don't see to understand the difference between velocity and acceleration. I also appreciate that you try to be an empiricist. As for quoting articles from Scientific American, indeed, it isn't the 80s any longer (when Scientific American was good). Today SA is replete with political nonsense, so seeing a dumb article such as the one you describe, is today, par for the course.