Something about global population trends seems to send otherwise sensible people over the edge. According to the United Nations, the planet’s population is due to reach 8bn on November 15th. Alarm bells are clanging. Population pessimists have long predicted mass famine. Now they add prophecies of environmental disaster as a result of too many people. Others worry about the opposite problem: “population collapse due to low birth rates”, tweeted Elon Musk, the self-proclaimed “chief Twit”, “is a much bigger risk to civilisation than global warming.” In fact, looking at population change during the past decade suggests neither of these mutually contradictory divinations of doom will prove correct.
It took a dozen years (from 1998 to 2010) for the global population to grow from 6bn to 7bn. It has taken the same length of time to notch up the next billion. Against the backdrop of catastrophising, it is worth recalling what is behind this growth: longer lives, improvements in nutrition and public health; falls in infant mortality, disease and maternal deaths in childbirth. The world’s population carried on growing even in the teeth of the co-19 pandemic, despite the virus killing—according to The Economist’s best estimates—between 16m and 28m people. That would represent as much as a fifth of all deaths over the period.
Not much eence, then, of a global demographic collapse. Nor is one coming soon. On current trends, the global population will reach 9bn in 2037 and peak at 10.4bn sometime between 2080 and 2100.
The spectre of overpopulation looks equally unthreatening. Even though the extra-billion milestones are passing with the same regularity, the global population growth rate is falling fast. In 1963 total population rose by 2.3%. In 2022 it grew by just 0.8%, the lowest rate since the 1950s.
How can growth be falling while the population rises steadily? The answer is that inertia and momentum matter hugely. The 1990s and 2000s were both decades of relatively fast population growth. The children born then are now reaching their child-bearing years. The number of adults aged between 18 and 49 was 2.2bn in 1987. It is 3.6bn now. But this bumper crop of potential parents seems to be choosing to have smaller families. The total fertility rate, which measures how many children a woman can expect to have in her lifetime, has plunged from 3.3 in 1990 to 2.3 now, only slightly above the “replacement rate”—at which the population stays constant—of about 2.1. Though the population continues to rise, the increase hardly seems uncontrolled.
As ever, the global average disguises big regional differences. About half the world’s projected population growth between 2022 and 2050 will occur in just eight countries. Five of those are in Africa (Congo, Egypt, Ethiopia, Nigeria and Tanzania). The other three are in Asia (India, Pakistan and the Philippines). India will probably overtake China as the world’s most populous country next year. Africa overtook the combined populations of Europe and North America this year (in 1980 it had just one-third of their total). That will have both environmental and social implications.
Start with the environmental consequences. People in India and Africa pollute far less than their counterparts in America, Europe or China. According to the UN, poor and lower-middle-income countries account for only a seventh of the world’s emissions of carbon dioxide. But 90% of population growth over the next decade will come from these less-polluting countries. Population growth can sometimes make environmental pressures worse: think of drought-stricken Somalia. But globally, there is little eence that population growth, in and of itself, contributes as much to global warming as rising living standards do.
A similar point can be made about ageing societies. Two-thirds of the world’s people live in countries where the population is flattening or falling and where the total fertility rate is below the replacement level. In 61 mostly rich countries, the UN reckons populations will fall by 1% or more between now and 2050. Shrinking societies certainly face social problems: one big one is that there are proportionately fewer people of working age to proe for those who have retired, implying higher taxes or lower spending on the elderly.
Whether this constitutes a threat to civilisation is not so clear. On pessimistic estimates, a rich country such as Germany could have roughly the same population in 2100 as it had in 1950 (and that assumes its very low fertility does not change). That would be a big change from today, but it is not clear that it would be catastrophic. Over the next eight decades rising productivity could well mean that fewer workers are needed to support a given number of retired people, in the same way that fewer are needed to grow crops or pour steel than would have been 80 years ago, in 1942.
None of this is to deny that the world faces big problems of environmental degradation and political upheaval. But the 8bn mark does not portend demographic disaster. Instead, Earth’s population growth seems to be having something of a Goldilocks moment: neither too hot nor too cold. ■
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