The message is finally getting through: the population bomb has fizzled out and fertility is falling nearly everywhere in the world.

Sometime in the next few years (if it hasn’t happened already) the world will reach a milestone: half of humanity will be having only enough children to replace itself. That is, the fertility rate of half the world will be 2.1 or below. This is the "replacement level of fertility", the magic number that causes a country’s population to slow down and eventually to stabilise… The move to replacement-level fertility is one of the most dramatic social changes in history.

This is the cheerful message delivered in the October 29 issue of The Economist. If the world’s leading news magazine has finally swung around, the day is not far behind when population controllers will be looking for jobs:

At a time when Malthusian worries are resurgent and people fear the consequences for an overcrowded planet, the decline in fertility is surprising and somewhat reassuring. It means that worries about a population explosion are themselves being exploded—and it carries a lesson about how to solve the problems of climate change. (The Economist, "Falling fertility")

What The Economist is responding to is frightening scenarios of environmental destruction brought about by swelling populations. Its reassuring message to those who fret about over-population is that the world’s population will grow from 6 billion to 9 billion in 2050. But then it will plunge. It is already dropping in some countries – Russia’s population will probably fall by one-third! So there is no population lever that environmentalists can shift to stop the degradation of the environment and climate change.

If population policy can do little more to alleviate environmental damage, then the human race will have to rely on technology and governance to shift the world’s economy towards cleaner growth. Mankind needs to develop more and cheaper technologies that can enable people to enjoy the fruits of economic growth without destroying the planet’s natural capital… Falling fertility may be making poor people’s lives better, but it cannot save the Earth. That lies in our own hands.

So far, so good. But astonishingly, The Economist fails to see that there are any problems with falling fertility. Instead, it emphasises the notion of a "demographic dividend". As fertility falls, a bulge of working adults appears on the population pyramid, like the tummy on a well-fed, prosperous banker. With a significant proportion of adults working and paying taxes, conditions are right for economic development. It is, says The Economist, "a Goldilocks moment".

However, bafflingly, what it fails to take account of is what happens after the bulge works its way towards the top of the pyramid. Then younger workers will be staggering under the load of supporting both their children and their parents. The good news is also bad news, very bad news indeed. In fact, The Economist’s analysis of falling fertility must rank amongst the shallowest analyses it has ever published.

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