Why we should calm down about the population explosion

You might have thought the eurozone deal would have left something of a hysteria gap in the newspapers. After all, whether it works in the long term or not (it won’t), it did at least ensure that this isn’t the week we have to deal with a global systemic banking crisis.

However in the end there was no gap. The outpouring of hysterical end-of-the-worldism was instead supplied by the news that at some point this week, the seven-billionth person in the world was born.

Read the articles on this, and it is clear that the only person who should feel any joy about this will be the babe’s mother. For the rest of us, it is nothing short of disaster.

According to the population forecasters, baby seven-billion is just a step on the road to baby eight-billion. Worse, by 2050, baby nine-billion will be born and the world will be the equivalent of two Chinas bigger than it is now.

And we will still have learned nothing: most forecasters assume that by 2070 there will be ten billion of us engaged in a Malthusian scrap over water, fertiliser, space and food. Disaster can only follow – unless we can somehow find a way, via a new green revolution or the total decarbonisation of our economies, to make more from less. It is compelling stuff.

However, the rarely-mentioned thing about it is that it is as likely as not to be nonsense.

A report published in May by Deutsche Bank made the case for the global population peaking far sooner than the UN and its like forecast.

Why? Because the whole idea rests on two unlikely assumptions.

The first is that everyone will end up living as long as the Japanese currently do. This seems unlikely (people who are old in Japan today have the kind of healthy diet that neither anyone in the West – or indeed their own children – are ever likely to have again).

The second is that all countries maintain “replacement level fertility”. But already this just isn’t happening. Not only is population growth slowing everywhere, but Japan and Germany have seen “almost zero population growth over the last decade”. The Chinese, Russians and Brazilians already fail to replace themselves (women have fewer than 2.3 children each) and fertility rates in India are falling fast.

The result? We might reach nine billion, but then global fertility will fall to the replacement rate within 15 years and “our species should no longer be expanding”. In the 20th century, the global population rose fourfold. It is unlikely to even increase by a half this century.

Of course, it might not even take that long for this would-be disaster to go away.

As professional optimist Matt Ridley points out, we haven’t the faintest idea how many people there are in the world anyway. Most countries only do a census every couple of decades, and they are very rarely accurate. Sometimes they are ludicrously low (people don’t fill in the forms in case they get taxed), and sometimes they are ludicrously high (politicians bump the numbers up to get more aid or government support). Overall, says Ridley, it is just silly to think we know how many people there are to more than the nearest couple of hundred million.

The fact is that the human race is the only one that “drops its birth rate when its food supply increases.” What Ridley means by this is that humans have fewer children as they get richer. Birth rates go down very very quickly as soon as prosperity in a country increases: where income and the availability of work increases and where child mortality and famine falls, the birth-rate falls.

That’s probably because humans – uniquely in the animal world – tend to focus on quality not quantity when it comes to children: as soon as they can, they are more interested in having and educating a few well, rather than creating a house full of spares.

Urbanisation has an effect too. As Fred Pearce, author of Peoplequake, points out, if you live on a peasant farm, kids are pretty useful from a young age – they are an economic asset you might as well keep making more of, particularly as they are all you are ever going to get in the way of life insurance. But in a city? They’re a cost.

That’s why urban people mostly have two children instead of six. All this comes with its own problems, of course. Not only do urban children use more resources than rural peasant children but, as Pearce says in the Mail, static or falling populations tend to mean the same for economic growth. Witness Japan.

• PS Matt Ridley is visiting me today in advance of a lecture he is giving in Edinburgh tonight– if you have any questions for him send them to me on my Twitter account. I’m at @merrynsw or you can just click on the button above.