For those who worry about global warming and all the other damage humans are doing to our planet, the latest news on world population growth doesn’t seem good. Fortunately, however, the relationship between population and the environment is paradoxical.
The United Nations Population Division updated its projections in June. From its present 7.7 billion, the world’s population is projected to have grown by 2 billion in 2050. It should reach a peak of nearly 11 billion at about the end of this century, before it starts to fall.
Fortunately, projections are just projections, based on a lot of assumptions that may or may not prove to have been accurate. Some prominent demographers believe the UN’s assumptions are too pessimistic.
It’s a mistake to imagine that controlling world population growth is just a matter of access to effective contraception. Economic development also plays a big part.
It’s the activity of humans that generates greenhouse gas emissions and does other damage to the natural environment, using up non-renewable resources, over-using renewable resources such as fish stocks and forests, damaging soil and waterways, and making species extinct.
So the more people, the more damage. Most human activity is economic – people earning their living. And, the way economies are organised at present, the richer people become, the more damage they do.
But here’s the paradox: the richer people become, the fewer children they have.
As my favourite magazine, The Economist, noted in an article, before the Industrial Revolution the typical woman probably had seven or more children. In 1960, the global fertility rate was six children per woman. Today it’s 2.5.
Within that global average, the fertility rate in rich countries is 1.7 children, below the replacement rate for a stable population of 2.1. In middle-income countries it’s 2.4, not far above replacement. In poor countries, however, it’s 4.9 children.
The first economic factor to reduce family size is urbanisation. When you leave the farm, you don’t need as many kids to help with the work. (Both my parents grew up on farms early last century. Dad was one of 14, and Mum one of eight. Their four children, however, had an average fertility rate of 2.5.)
But perhaps the most important factor is the spread of education, particularly of girls. It’s well established that the more years girls spend at school, the fewer babies they have.
“Education reduces fertility by giving women other options,” The Economist says. “It increases their chances of finding paid work. It reduces their economic dependence on their husbands, making it easier to refuse to have more children even if he wants them.
“It equips them with the mental tools and self-confidence to question traditional norms, such as having as many children as possible. It makes it more likely they will understand, and use, contraception.
“It transforms their ambitions for their own children – and thus the number than they choose to have.”
Worldwide, the proportion of girls completing primary school has risen from 76 per cent in 1997 to 90 per cent today. The proportion completing lower secondary school is nearing 80 per cent.
Fertility rates are low in Europe – particularly in Italy (1.33) – and in Japan (1.37). They’re below replacement rate in New Zealand (1.9), Australia (1.83) and the US (1.78).
But the lowest fertility rates are in emerging Asia: Taiwan (1.15) and South Korea (1.11). In the world’s most populous country, China, it’s 1.69, thanks to the one-child policy. After the relaxation of that policy it rose only briefly. Flats are too small and childcare too limited.
By contrast, India’s rate is 2.24, pretty close to replacement. And it varies greatly from 1.8 in wealthy states such as Maharashtra, to more than 3 in poor states such as Uttar Pradesh. Even so, India's population is expected to overtake China’s in 2027.
Because fertility rates cover the whole child-bearing lives of women, it takes a long time for the population of a country that's a bit below the replacement rate to start falling – assuming they don’t top up with immigration, as we do.
Even so, 27 countries’ populations have fallen since 2010 – sometimes with low fertility rates reinforced by high emigration. Over the next 30 years, 55 countries’ populations are projected to fall – almost half of them by more than 10 per cent. China’s may fall by about 31 million, or 2 per cent.
So what’s the problem? In a word: Africa. Its painfully slow rate of economic development leaves it still with fertility rates of five or six, including big countries such as Nigeria, the Congo, Ethiopia and Tanzania.
The best hope that the world’s population will stop growing sooner than the UN projects is that it has underestimated the rise of girls’ education in Africa (and India and Pakistan).
Of course, economic development is two-edged. It may stop population growth, but it makes everyone else richer and thus makes more demands on the environment.
Just as we can limit climate change without reducing energy use by switching to renewable sources, so we could reorganise the economy in ways that ensured continued economic growth didn’t involve continued destruction of the environment. If we had the will.
