The issue of overpopulation has been a bugbear of the popular imagination for decades, and remains so especially into the 21st century, when humanity crossed its seven billion mark — unprecedented in both size and scale of growth (consider that while it took millennia for humanity to finally reach a billion only in 1804, it took just another two centuries to hit seven times that number).
Given all that, it is perfectly understandable why people would be concerned about the impact such rapid growth is having on everything from the environment to global food supplies and energy resources (to say nothing of the subsequent social, political, and economic instability that results from such strains).
But as the following video from The Economist shows clearly, the global population — though set to grow by another two billion by 2042 — has already begun slowing down in its rate of expansion.
An excerpt from the original article nicely sums up the visual data:
The pyramid was characteristic of human populations since the day organised societies emerged. With lifespans short and mortality rates high, children were always the most numerous group, and old people the least. Now the shape of the global population is changing. Between 1970 and 2015 the dominating influence on the global population was the fertility rate, the number of children a woman would typically bear during her lifetime. It fell dramatically over the period, meaning that the world shifted from having larger to smaller families. The age groups start to become markedly smaller only about the age of 40, so the incline starts much further up the chart than with the pyramid. The shape looks more like the dome of the Capitol building in Washington, DC. Between 2015 and 2060 the biggest influence upon the population will be ageing. Small families are already becoming the norm, the fall in fertility is slowing down and now almost everyone is living longer than their parents—dramatically so in developing countries. So, by 2060, the dome will have come and gone and the shape of the population will look more like a column (or perhaps an old-fashioned beehive).
In other words, barring any sort of unlikely massive uptick in the global birthrate, humanity is currently entering its peak of population: shortly after hitting nine billion, growth will begin to stagnate as the number of people of childbearing age declines.
Indeed, a map of fertility rates by nation shows that most of the world’s countries (many of them developing) are already experiencing slowing, stagnating, or even shrinking populations.
Keep in mind that a fertility rate between 2-3 (green) is considered the sweet spot for stable growth: any lower and you face rapid population aging followed by, and concurrent with,population shrinking (unless immigration is high enough to offset the difference); any higher, and populations grow too quickly for resources and institutions to accommodate. Both circumstances bring their own challenges and issues, which in turn vary from country to country.
But note how the majority of the world’s population growth is taking place in the developing world, especially in Africa (where not a single country has a total fertility rate of less than 2. Indeed, as The Economist video showed, 90 percent of the world’s youth will be living in emerging economies, with Africa having more young people than any other continent.
Conversely, it is mostly mid- to high-income countries whose fertility and birth rates are low, and whose populations have already begun stagnating, if not shrinking. The few exceptions — namely the U.S., Canada, the U.K, Ireland, and France — are growing mostly due to immigration and the subsequent increase it brings to the birthrate (since immigrants tend to have more children than native-born individuals).
The following map shows the population growth of the world’s countries by percentage between 2000 and 2010.
Notice again a similar pattern: broken down by country, most of the world is seeing low to negative population growth, even if the world as a whole is growing. Basically, the global population is growing highly unevenly, with a relatively small number of countries making up the lion’s share of total growth.
Moreover, as the video showed, much of this population “growth” is really a reflection of more people living longer: previously, population stabilized or shrank because enough people would die by the time the next generation came of age to have children. But as more people stick around longer, even the effects of a low birthrate will not be felt since so many people remain.
Hence why countries like Germany and Japan — which have long had some of the lowest fertility rates, and thus fastest-aging populations, in the world — did not begin to experience stagnation or decline until decades later. Their peoples are also among the longest-lived (note that higher immigration as of late has lead to modest but noticeable growth in Germany).
So what is the significance of all this? Well, there are many issues and challenges facing the world now and in the future as population dynamics rapidly change. Frankly, I do not have time to get into the larger social and economic ramifications of having whole societies without enough working-age adults; too many older people strains social security systems
But with regards to the most commonly cited concern — that of overpopulation straining resources — the solution is simple to recognize but difficult to implement: more efficient allocation of resources on a global level.
There is plenty of capital, food, and energy in the world to go around, but most of it is concentrated in and consumed by a wealthy few nations (and within those nations in turn, by a wealthy few people). Finding a way to allocate such resources to where it is needed most would lift hundreds of millions from poverty.
Consider that food output is well above what is needed, but that chronic malnourishment afflicts hundreds of millions of people — especially in fast-growing populations — because much of that food does not go to the poorer parts of the world, and 40 percent is wasted altogether. (To further underline this misallocation, in recent years the number of overweight and obese people in the world has outnumbered the malnourished.)
Moreover, shrinking wealthy countries could benefit from taking in the younger workers overflowing fast-growing poorer nations — as several immigration-friendly nations are experiencing — but there is (and would be) much resistance.
Perhaps as the world continues to develop its global consciousness — and with it the necessary global institutions to implement such policies — we will find a mutually beneficial way address the mismatch in demographic changes. There is a lot more to this topic that I have not touched on given my time constraints, but as always I welcome your thoughts and feedback.