As I laid out in How We Did It, the human population has simply exploded over the last two centuries. It took almost all of human history for the human population to reach the first billion. But once this happened, around 1800, it only took a century for the population to double.
The number of human beings on our planet exceeded 6 billion in 1999, and is projected to hit 9 billion before the middle of the 21st century. The current population growth rate is estimated at 1.03 percent, or 154 births every minute.
In this essay, I write about the history of population predictions and how and why we need to view population shrinkage as essential. Use the toggle switches below to expand each section.
Demographers have long attempted to model population growth, and their projections have been used to inform policy decisions. Historically population projections have differed in their estimates, which has informed policy and also influenced the public consciousness.
Concerns of overpopulation began taking hold in the mid-20th century. In my youth—which I admit feels like it could have been the 14th century but was more like the 1970s—this was an enormous fear. In the 50s and 60s, amid climbing population numbers, demographers and futurists concluded that we were on the route to a population explosion.
These fears were partly fueled by The Population Bomb, published by Paul and Ann Ehrlich in 1968. One of the most influential books of the 20th century, it spoke of the disasters that humanity would face on an overpopulated planet. The Ehrlichs projected that, because of the rapidly increasing population outstripping food supply, hundreds of millions of people would starve to death in the 70s and 80s.
The Ehrlichs weren't the only people theorizing about population. To pick a counterexample of sorts: German chemist and futurologist Walter Greiling suggested natural limits to human population expansion. His predictions came in the 1950s, when England was also experiencing rapid population growth. He estimated that the world population would balance out at about 9 billion, earlier rather than later in the 21st century. He argued that, in time, population growth would inevitably decline due to either a rise in death rates or a fall in birth rates.
While it is still yet to be seen if Greiling was right in his predictions, the Ehrlichs' pronouncement of mass starvation did not come to pass, partly because of the Green Revolution in the 1970s, which dramatically increased harvests. Because their predictions of doom didn't come true, it is sometimes overlooked that their predictions about population numbers more or less did. The population continued to skyrocket, doubling from 3 billion in 1960 to 6.1 billion in 2000—within just 40 years.
Estimates made in the 2000s tended to predict that Earth's population would hit its peak around 2070; this prediction that population would peak in the 21st century was later revised, with the UN projecting in 2015 that population would hit 11.2 billion in 2100. Continued population growth is attributed to high population growth rates in developing countries, particularly those in Africa, and to a lesser degree, significantly lower death rates most everywhere.
Currently, the UN is 95 percent confident that the trajectory of population growth will fall within a well-defined range. On the lower side, the UN predicts the population peaking around 2070 before slowly declining; on the upper side, the population could hit 13 billion by 2100 and continue to climb.
In other words, according to the UN, the population is going to continue growing for at least another 48 years. It makes sense to assume that they're right and start preparing for an increasingly overcrowded planet—after all, the UN does have a pretty decent track record. But there's reason to believe that current projections for the future might be off the mark— and significantly.
Although overall human population growth has been exponential, this is not the case all over the world. While some countries, particularly developing ones, are experiencing rapid population growth, others' growth rates are much slower; some, in fact, are experiencing contractions in population size.
China's population, for one, is shrinking by around 400,000 people a year. China still claims that its population is expanding, but even so, its population is expected to peak at 1.4 billion in only four years time and, according to one study, will almost halve by 2100 to around 700 million.
Population decline isn't a prospect that only China faces; many other countries are in a similar boat. Several East Asian countries' fertility rates hover around 1.0, and populations in Europe are shrinking as well. Likewise, fertility has fallen below replacement rates in the U.S. This means that the world population could actually shrink sooner than the UN's predictions might suggest.
Yes, shrinking. Fertility rates have been on the decline since the 1950s: in 1965, the average woman in the world had over five children, but today, the average per woman is below 2.5 children.
Sustained low fertility levels have resulted in 27 countries or areas experiencing a reduction in population size by 1 percent or more; this is expected to continue, with 55 countries or areas' populations projected by the UN to decrease by 2050. China, in particular, is estimated to face a population drop of 31.4 million, or around 2.2%.
There are many reasons for low fertility rates. Women are receiving more education, and contraception is becoming easier to access. Rapid urbanization has played a part, as it gives women better access to education and contraception—in 2007, for the first time in history, the majority of people in the world lived in cities. Today, that figure stands at 55 percent, and in thirty years, it will be 67 percent. Women are also becoming more financially independent, and in many cases, finding satisfaction and purpose outside of motherhood.
This all points to the fact that the global population will almost certainly start to decline—the only question is when.
Some analysts believe that fertility rates will experience a more dramatic drop than what's laid out in the UN estimates, even in the "low-fertility scenarios" depicted. Norwegian academic Jørgen Randers, for example, believes that the population will peak at 8.1 billion people in 2040.
Randers' prediction, significantly different from the UN's, is based on observations of falling fertility rates due to women's education, increased urbanization, better access to contraception, and continuing medical advancements. According to Randers, the effect of declining fertility rates outstrips that of rising life expectancy.
A Deutsche Bank report projects the stabilization of the world population at around 9 billion in the late 2050s, when it will then start declining. These projections are echoed by demographers from the Wittgenstein Center, who believe that the population will peak around 9.4 billion in 2070 and then stabilize at around 9 billion in 2100 due to strides in global education. In 2020, The Lancet published a study predicting that the world population would peak at 9.7 billion in 2064 before declining to 8.8 billion in 2100.
There is a framework for thinking about population dynamics as populations get more prosperous. It is called the demographic transition—in other words, when societies get richer and mortality falls, birth rates fall.
The demographic transition has five stages:
- Stage 1: both birth and death rates are high; people have more kids, but because of high infant mortality, population remains relatively stable at this stage.
- Stage 2: infant mortality falls but the birth rate remains high; because people are still having many kids, but most of them survive to adulthood, the population rapidly increases. This lasts for around one or two generations, and it's likely that many developing countries are in this stage.
- Stage 3: falling birth rates because of higher certainty that children will survive to adulthood. Family planning, more women getting educated, better access to contraception, and other factors also contribute to the decrease in births.
- Stage 4: birth and death rates are both low; the population falls and eventually stabilizes.
- Stage 5: this is more uncertain, as we don't know what "steady state" is: population might remain stable, shrink due to below-replacement reproduction, or slowly pick up again.
Today, most developed countries have joined Britain, the first country to enter the transition, with low birth and death rates. Other countries, most commonly developing ones, are experiencing falling death rates, with birth rates not yet following suit.
As mentioned, the UN actually has a history of making pretty accurate predictions. But like any projection of the future, these estimations also have flaws and shortcomings: UN data on indicators like fertility and life expectancy in China, Pakistan, and Bangladesh, among other countries, has been problematic in the past.
It's difficult to tell how quickly the fertility transition will proceed for transitional or pre-transitional countries—and when it will stop. On the other hand, for post-transitional countries, the challenge is predicting fertility fluctuations and what future trends will be.
But based on what we know now, it seems that falling fertility rates could actually cause the global population to peak sooner and/or lower than has been predicted (barring unanticipated fertility-boosting developments, of course, such as the World War II baby booms).
My view is that the population is going to fall far faster than anyone has anticipated. And now we'll talk about why that is a really good thing.
How does a shrinking population compare with a growing one? If policymakers keep going on about population growth and how important it is, there've got to be merits to adding more people to the planet, right?
The truth is, although population growth is associated with economic growth and is thus touted as highly desirable, limitless growth of population—and, subsequently, consumption—is unsustainable on a finite planet.
A growing population places enormous stress on the world's food and water resources, exacerbates losses of wild lands and biodiversity, and degrades life-supporting natural resources. A growing population equals growing pressure on our planet. And, so far, we've pretty much done nothing but put increasing pressure on our planet. That's not wise; Earth has a breaking point that we are rapidly approaching.
As biologist Edward O. Wilson put it:
"The pattern of human population growth in the 20th century was more bacterial than primate. When Homo sapiens passed the six billion mark we had already exceeded by as much as a hundred times the biomass of any large animal species that ever existed on the land. We and the rest of life cannot afford another 100 years like that."
At our current rates of consumption, we'd need four Earths to lift everyone alive today to the U.S.' standard of living. Just imagine the appalling amount of resources an even bigger population in the future would need—an amount that the planet is just unable to provide.
Food production, for one, would have to be scaled up to meet the massive spike in demand; if the UN's population projections come true, we'd have to increase agricultural output by at least 50 percent by 2050, as a result increasing agriculture's environmental footprint by 50-90 percent. This dramatically increases the threat to global biodiversity and ecosystem services.
Growing demand for energy and materials is just as much of a concern. Technological advancements in the past few centuries have led to dramatic increases in our quality of life, but also significant increases in energy consumption. And, as mentioned in the chapter on Jevons' Paradox, improvements in efficiency aren't going to solve the problem—if anything, they'll only worsen it. And, as also mentioned before, renewable energy comes with its own host of challenges to overcome.
Finally, with more people comes more demand for land. The new facilities and infrastructure that we're going to need for all these new people will require lots of land, which means further encroaching on the already diminishing natural land left on the planet. After agriculture, urban growth has been identified as one of the biggest causes of habitat destruction.
Of course, one might ask: if the problem lies in resource consumption, as discussed in previous chapters, why shouldn't we just focus on that instead? Surely Earth could handle more people if we all collectively consume less?
That is definitely true—Earth would, technically, be able to support more people if we all used fewer resources. But even if we all consumed at the scale that, say, France does, as opposed to the U.S, we'd still need two and a half Earths to support that lifestyle, as compared to four. Yes, reducing consumption should be our primary focus, but overpopulation certainly doesn't help the issue.
And this is becoming increasingly recognized. In fact, lower population growth is regarded as a requirement for meeting the UN Sustainable Development Goals. According to the International Panel on Climate Change (IPCC), we could lower greenhouse gas emissions by 30 percent by 2100 simply by improving women's access to contraception. As the scholars Rob Dietz and Dan O'Neill put it:
"We need smaller footprints, but we also need fewer feet."
Historically, large, growing populations have been seen as a sign of a successful society and economy. Periods of decline were associated with decadence or some kind of societal failing, resulting in falling birth rates being viewed as a problem. This still holds true today, where sluggish population growth remains a concern for policymakers, and the dangers of falling birth rates are continually bemoaned by writers and journalists.
A shrinking population comes with its own set of complications, many of which are frequently mentioned in the media: an aging population, shrinking tax base, falling housing prices, decreasing GDP, a weaker military, and so on. These are certainly challenges that require concerted and systematic effort to tackle. But upon closer scrutiny, some of these arguments against falling populations are overstated, lack substance, or in some cases, obscure actual advantages.
Aging populations, for one, shouldn't be considered a social problem—medical advancements that have allowed us to postpone death are one of the most important successes in human history. The real problem lies in how we have not yet assimilated this new reality and taken steps to cope with it.
The older workers of the future are likely to be healthier and better educated than today's workers, while improving healthcare and longevity are likely to translate into older workers retiring later or re-entering the workforce. This means that most economies should have a continuous supply of high-quality workers in the labor force even with an aging population, which buys time for governments to make technology and policy adjustments to accommodate this demographic shift.
Similarly, a shrinking tax base (i.e., fewer contributors to social security) has led to social scientists recommending increasing fertility rates, but what this does is just increase the number of contributors to social security in 30 years. This doesn't really solve the problem if the real goal is to have more contributors than pensioners. There are many solutions to this, including policies to reduce unemployment, increasing women's access to the workforce, and postponing retirement age, that could be implemented to ease the burden on taxpayers.
There also isn't much empirical evidence that modern population decline will negatively impact individual wealth. Most concerns about how GDP will be affected can only be justified if international influence and defense are prioritized over individual welfare. Though GDP tends to increase with population, it has been recurrently criticized for being a poor indicator of individual welfare. There has been no association proven between population size and GDP per capita.
A shrinking population also means that resources can be channeled towards improving the standard of living—when populations shrink, but the stock of capital goods doesn't, the average wealth per person should increase. This allows for investment in quality-of-life improvements instead of providing for a growing number of people on a finite planet.
So the human population is, at some point, going to decline—and I'm here to tell you that's no cause for alarm. Rather than depend on unlimited population growth, we will need to find better, more creative ways to fund social welfare programs and keep the workforce robust.
The short-term solution to a shrinking population has often been migration. But when every population in the world is shrinking or about to start doing so, migration will no longer be effective. That's not the point anyway—instead of trying to maintain population numbers, we should be thinking of long-term solutions to help us cope with declining birth rates. This has only placed the burden on women to continuously create new generations of workers.
One way of doing so is through technology, which has enormous potential in helping us deal well with declining populations and mitigate its impacts. In fact, the rise of automation makes too many workers, rather than too few workers, the bigger problem. Although the number of China's 20- to 64-year-olds will drop by around 20 percent in the next three decades, productivity and prosperity are still estimated to rise, partly due to investments in technology in the workforce.
New technologies can also raise labor force participation rates of older workers, and improve overall productivity, by complementing and augmenting physical labor.
This can be done through (this is one list—there are many other ideas):
- Skill substitution, such as through the use of robots and automation
- Supporting workers, such as with remote-office and collaboration tools and adaptive technologies, and machinery to make tasks less physically demanding and more accessible to older workers
- Skills upgrading and education, such as online learning platforms and skill development technologies to aid physical and cognitive capacities of older workers
- Matching workers to jobs that are most suitable for them, such as through job portals
- Improving health and extending life expectancy in general, such as through bioinformatics, biotechnology, and digital therapeutics
- Improving and transforming the workplace, such as through remote platforms, automation, AI and machine learning
In my writings, I usually don't talk about public policy and focus instead on individual behavior change. This is not because I don't believe policy changes are useful—it is because policy is way outside my knowledge base. But I can touch on a few things that are obvious.
In the case of an aging population, policy can help draw seniors back into the workforce, such as by removing disincentives to work and adding benefits for returning to work after retirement. Upgrading workplaces to accommodate older workers better and improving working conditions can help as well. Seniors who have trouble finding work might also benefit from policies against age discrimination in hiring.
Policy changes can help increase female participation in the workforce. Despite steady economic growth and better access to education, there are still much fewer women than men in the workforce. In particular, removing gender bias in education, the workforce, and households in Asian economies can help increase female workforce participation and increase per capita income by 30 percent.
Introducing job quotas could also help counteract discrimination while providing vocational training for women can incentivize them to enter the workforce. Other initiatives could be rolled out, including policies on parental leave and childcare or flexible work hours to accommodate domestic responsibilities for both men and women.
All of this should be accompanied by an intentional cultural shift that doesn't require women to sacrifice so much of themselves and their lives when they have children. Regardless of the impact of this cultural shift is on birth rates, the result is still positive: healthier families and happier people who have more autonomy on how to live their lives.
It's helpful to remember that falling fertility rates are largely caused by better access to contraception, family planning, and more women being educated. All these point to the great strides the world is making, especially in developing countries, towards female empowerment and gender equality. Women have the choice to walk down the path of motherhood intentionally. Women choosing to have fewer or no children should not be framed as a failure of the state but as the sign of a more open, flexible society.
This is objectively a cause for celebration.
Fewer people = a safer planet
While the jury is still out on when exactly Earth's population will begin its decline, it feels to me that it is inevitable and will happen sooner than we think. We should embrace and applaud this decline. Below-replacement birth rates may sound scary but are in fact manageable and desirable.
There is no other way to a sustainable planet.
The challenges of population growth
- Report | Demographic Vulnerability: Where Population Growth Poses the Greatest Challenges
- Interview | The Population Bomb, 50 Years Later: A Conversation with Paul Ehrlich
- Book chapter | The Consequences of Rapid Population Growth
How technology can help with a shrinking population
- Report | Asian Economic Integration Report 2019/2020: Demographic Change, Productivity, and the Role of Technology
- Blog post | 6 Ways Technology Can Make a Big Difference for Aging Populations
Addressing both population and consumption