28 May 2022

OneZero: “By the End of This Century, the Global Population will Start to Shrink”

The great defining event of the 21st century — one of the great defining events in human history — will occur in three decades, give or take, when the global population starts to decline. Once that decline begins, it will never end. We do not face the challenge of a population bomb, so rampant in the popular imagination, but of a population bust — a relentless, generation-after-generation culling of the human herd. Nothing like this has ever happened before.

If you find this news shocking, that’s not surprising. The United Nations forecasts that our population will grow from 7 billion to 11 billion in this century before leveling off after 2100. But an increasing number of demographers around the world believe the UN estimates are far too high.

More likely, they say, the planet’s population will peak at around 9 billion sometime between 2040 and 2060 and then start to decline. By the end of this century, we could be back to where we are right now and steadily growing fewer.

The demographic transition model, which was first developed in 1929, used to contain only four stages. Stage four, the final stage, envisioned a world in which life expectancy was high and the fertility rate was low, around the level needed to sustain the population: 2.1 babies per mother (one per mother, one per father, and an extra 0.1 to account for children who die in infancy and women who die before childbearing age). But as it turned out, there is a fifth stage: one in which life expectancy continues to slowly increase, even as fertility rates continue to decline below the replacement rate, eventually leading to a declining population. Just about the entire developed world is in stage five.

Darrell Bricker & John Ibbitson

Taking a break from the urgent issues of today, here’s a worldwide trend that will certainly reshape our societies in the coming century: the upcoming shift from the population growth we experienced since the dawn of civilization to a stagnating and shrinking population. There were of course numerous dips in various regions in times of famine and plague, but the overall trend was ascending owing to a high birth rate. Modern science and civilization have reversed both fundamentals: better healthcare has decreased child mortality and increased life expectancy, while increased urbanization, education and secularism have reduced previous pressures to have as many children as possible.

Large crowd of people seen from above
Paul Ehrlich warned in the late 1960s that the world’s population was growing faster than the Earth could sustain. Photograph: Dmytro Varavin/Getty Images

As always, it’s not straightforward to extrapolate trends far into the future, especially during dynamic times. Some studies suggest the peak could be reached sooner, with a maximum world population of 9.7bn in 2064. The ongoing coronavirus pandemic has taken a toll on life expectancy in many countries with older residents, and future pathogens could similarly impact population growth. Global warming will likely impact these trends as well, both directly through more intense heat waves and other climate disasters, and indirectly by accelerating the spread of diseases beyond their current ranges. On the opposite side of the spectrum, increased digitization and automation could allow groups of people to return to smaller, rural-like communities, and have more time available, which could mean more babies.

We know that urbanization changes the economic calculus of having children and leads to the empowerment of women through education. Recent research has shown that other factors are in play as well. One of them is the decline in the ability of kin to influence kin. If you live in a more rural, less developed society, your social environment most likely revolves around the family, in which the elders endlessly nag the young to get married and have kids. But as societies become more modern and urban, friends and co-workers replace siblings, parents, uncles, and aunts. This change is the critical factor in decreasing birth rates, writes psychologist Ilan Shrira, of Chicago’s Loyola University, because family members encourage each other to have children, whereas non-kin don’t.

Another factor is the declining power of religion in most parts of the world. There is no question that societies in which religion wields considerable influence over individual decisions have higher fertility rates than societies in which religious influence is minimal. Three WIN/Gallup polls, taken in 2008, 2009, and 2015, asked respondents whether they felt religious. In Malawi and Niger — which, as we’ve seen, have among the highest fertility rates in the world — 99 percent of those polled answered yes. Only 39 percent said yes in Spain, which is now considered one of the least religious countries in the world. (Interesting correlation: Societies where the power of the Catholic Church rapidly collapsed, such as Spain, Quebec, and Ireland, tend to go from having relatively high to relatively low fertility rates especially quickly.)

Personally, I’m not especially worried about a declining world population – and not only because I’m unlikely to live long enough to experience that shift myself. By all accounts the change should be gradual enough that we could naturally adjust to these new conditions, and enjoy some benefits in the process. Fewer people living in denser urban areas, coupled with technological advances, would mean less land used for agriculture and living space. These areas can be rewilded, improving the carbon balance and returning the environment to wildlife. The economy would need to undergo fundamental changes to care for the elderly and rely on fewer working-age people, but that could be managed with increased automation and better taxation policies – and raising the retirement age, not a popular policy, but one that will surely be implemented incrementally. Migration would likely continue to be a thorny issue, caught between a rational calculation to keep population growing through an influx from countries with high birth rates and the irrational fears of existing citizens. But ultimately even migration will prove insufficient to keep population up as birth rates fall in Africa and rising living standards reduce the incentives for people to emigrate.

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