Bottom line: We simply cannot address climate change without including human population growth in the equation.
As I laid out in 'How We Did It', human population has simply exploded over the last two centuries. It took almost all of human history for human population to even reach 1 billion. But once this happened, around 1800, it only took a century for 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. Current population growth rate is estimated at 1.03%, 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.
Too many people?
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 not only informed policy but 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 fuelled in part 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 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: English chemist and futurologist Walter Greiling suggested that there were natural limits to human population expansion. His predictions came in the 1950s, when England was also experiencing rapid population growth. He estimated that 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. What is sometimes overlooked because their predictions of doom didn't come true is that their predictions about population numbers more or less did. Population continued to skyrocket, doubling from 3 billion in 1960 to 6.1 billion in 2000 — within a span of 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 in Africa.
Currently, the UN is 95% confident that the trajectory of population growth will fall between a well defined range. On the lower side, the UN predicts population peaking at 2070 before slowly declining; on the upper side, population could hit 13 billion in 2100 and continue to climb.
In other words, according to the UN, 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 — significantly.
Not so fast...
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 the Lancet 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. A number of 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 world population could actually shrink sooner than the UN's predictions might suggest.
Yes, shrinking. Fertility rates have been on a decline since the 1950s: in 1965, the average woman in the world had over 5 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% 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. Among those are the facts that women are getting more educated and contraception is becoming easier to access. Rapid urbanisation 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%, and in thirty years, it will be 67%. Women are also becoming more financially independent, and perhaps finding satisfaction and purpose outside of motherhood.
This all points to the fact that 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 scenario" ones. One of them is Norwegian academic Jørgen Randers, who believes that 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 urbanisation, better access to contraception, and continuing medical advancements. According to Randers, the effect of declining fertility rates outstrips that of rising life expectancy.
Similarly, the International Institute for Applied Systems Analysis (IIASA) predicted in 2015 that world population will peak in 2040 at around 8 billion, while a Deutsche Bank report projects a stabilising of world population at around 9 billion in the late 2050s before declining. The report also cites low birth rates in both developed and developing countries.
This is echoed by demographers from the Wittgenstein Center, who project that population will peak around 9.4 billion in 2070, before stabilising at around 9 billion in 2100, based on strides that are expected to be made in global education. In 2020, The Lancet published a study predicting that world population would peak at 9.7 billion in 2064 before declining to 8.8 billion in 2100.
Get to know the "demographic transition"
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; because of high infant mortality, people have more kids. Population likely remains stable at this stage.
- Stage 2: infant mortality falls but birth rate remains high; because people are still having many kids but most of them survive to adulthood, population rapidly increases. This lasts for around 1-2 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; 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 United Nations 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. This has been associated with errors in projections on these same indicators.
It's difficult to tell how quickly the fertility transition will proceed for those countries that are transitional or pre-transitional, 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 global population to peak sooner and/or lower than has been predicted (barring unanticipated fertility developments, of course, such as the World War II baby booms).
My view is that population is going to fall far faster than anyone has anticipated. And now we'll talk about why that is a really good thing.
Population growth is terrible for the planet
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. A growing population equals growing pressure on our planet. And, so far, we've pretty much done nothing but put growing pressure on our planet. That's not wise; the 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 4 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% by 2050, as a result increasing agriculture's environmental footprint by 50-90%. This greatly 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 Jevons Paradox chapter, 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 are going to 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 the earth could handle more people if we all collectively consume less?
That is definitely true — the 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 recognised. 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% by 2100 simply by improving women's access to contraception.
"We need smaller footprints, but we also need fewer feet." - Dietz and O'Neill (2013)
How I learned to embrace a shrinking population
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 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 have been frequently mentioned in the media: an aging population, shrinking tax base, dropping housing prices, decreasing GDP, a weaker military, et cetera. These are certainly challenges that require concerted and systemic effort to tackle. But upon closer scrutiny, some of these arguments against falling populations are overstated, lack substance or, in some cases, actually advantages.
Ageing 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, while improved 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 labour force even with an ageing 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. Any concerns about how GDP will be affected can only be justified if national power, defence, and international influence are prioritised over individual welfare. Though GDP does tend to increase with population, it has been recurrently criticised as being a poor indicator of individual welfare. There has been no association made between population size and GDP per capita. Economic growth measured simply as GDP growth, as opposed to increase in GDP per head, has no bearing on individual welfare either.
A shrinking population also means that resources can be channelled 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 improving quality of life instead of providing for a growing number of people on a finite planet.
Technology can help us survive and thrive
So the human population is, at some point, going to decline — and I'm here to tell you that's no cause for alarm. We will need to find better, more creative ways to fund social welfare programs and keep the workforce robust, rather than depend on unlimited population growth.
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 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 China's 20- to 64-year-olds will drop by around 20% 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 labour force participation rates of older workers, and improve overall productivity, by complementing and augmenting physical labour.
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
Of course we need better policies
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 through removing disincentives to work and adding benefits for returning to work after retirement. Upgrading workplaces to better accommodate older workers and improving working conditions can help as well. Seniors who have trouble finding work might also benefit from policies against age-related aversion 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 household in Asian economies can help increase female workforce participation and increase per capita income by 30%.
Introducing job quotas could also help counteract discrimination, while providing vocational training for women can provide an incentive for them to enter the workforce. Other initiatives could be rolled out as well, including policies on parental leave and childcare, or flexible work hours to accommodate for 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 end result is still positive: healthier families and happier people who have more autonomy on how to live their lives.
Let's remember — and applaud! — the WHY
A reminder that falling fertility rates are caused by better access to contraception, family planning, and more women being educated. All these point to the great strides that the world is taking (and has made), especially in developing countries, towards female empowerment and gender equality. Women have a choice in becoming mothers and then to intentionally walk down the path of motherhood. Women having the choice to have fewer or no children should not be framed as a failure of the state, but seen 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 the earth's population will begin its decline, it feels to me that it is inevitable; will happen sooner than we think; and we should embrace and applaud this decline. Below-replacement birth rates may sound scary, but are 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
- Blogpost | 6 Ways Technology Can Make a Big Difference for Aging Populations
Addressing both population and consumption