Many of today’s most-respected thinkers, from Stephen Hawking to David Attenborough, argue that our efforts to fight climate change and other environmental perils will all fail unless we “do something” about population growth. In the Universe in a Nutshell, Hawking declares that, “in the last 200 years, population growth has become exponential… The world population doubles every forty years.”

But this is nonsense. For a start, there is no exponential growth. In fact, population growth is slowing. For more than three decades now, the average number of babies being born to women in most of the world has been in decline. Globally, women today have half as many babies as their mothers did, mostly out of choice. They are doing it for their own good, the good of their families, and, if it helps the planet too, then so much the better.

Here are the numbers. Forty years ago, the average woman had between five and six kids. Now she has 2.6. This is getting close to the replacement level which, allowing for girls who don’t make it to adulthood, is around 2.3. As I show in my new book, Peoplequake, half the world already has a fertility rate below the long-term replacement level. That includes all of Europe, much of the Caribbean and the far east from Japan to Vietnam and Thailand, Australia, Canada, Sri Lanka, Turkey, Algeria, Kazakhstan, and Tunisia.

It also includes China, where the state decides how many children couples can have. This is brutal and repulsive. But the odd thing is that it may not make much difference any more: Chinese communities around the world have gone the same way without any compulsion—Taiwan, Singapore, and even Hong Kong. When Britain handed Hong Kong back to China in 1997, it had the lowest fertility rate in the world: below one child per woman.

So why is this happening? Demographers used to say that women only started having fewer children when they got educated and the economy got rich, as in Europe. But tell that to the women of Bangladesh, one of the world’s poorest nations, where girls are among the least educated in the world, and mostly marry in their mid-teens. They have just three children now, less than half the number their mothers had. India is even lower, at 2.8. Tell that also to the women of Brazil. In this hotbed of Catholicism, women have two children on average—and this is falling. Nothing the priests say can stop it.

Women are doing this because, for the first time in history, they can. Better healthcare and sanitation mean that most babies now live to grow up. It is no longer necessary to have five or six children to ensure the next generation—so they don’t.

There are holdouts, of course. In parts of rural Africa, women still have five or more children. But even here they are being rational. Women mostly run the farms, and they need the kids to mind the animals and work in the fields.

Then there is the middle east, where traditional patriarchy still rules. In remote villages in Yemen, girls as young as 11 are forced into marriage. They still have six babies on average. But even the middle east is changing. Take Iran. In the past 20 years, Iranian women have gone from having eight children to less than two—1.7 in fact—whatever the mullahs say.

The big story here is that rich or poor, socialist or capitalist, Muslim or Catholic, secular or devout, with or without tough government birth control policies in place, most countries tell the same tale of a reproductive revolution.

That doesn’t mean population growth has ceased. The world’s population is still rising by 70m a year. This is because there is a time lag: the huge numbers of young women born during the earlier baby boom may only have had two children each. That is still a lot of children. But within a generation, the world’s population will almost certainly be stable, and is very likely to be falling by mid-century. In the US they are calling my new book “The Coming Population Crash.”

Is this good news for the environment and for the planet’s resources? Clearly, other things being equal, fewer people will do less damage to the planet. But it won’t on its own do a lot to solve the world’s environmental problems, because the second myth about population growth is that it is the driving force behind our wrecking of the planet.

In fact, rising consumption today far outstrips the rising headcount as a threat to the planet. And most of the extra consumption has been in rich countries that have long since given up adding substantial numbers to their population, while most of the remaining population growth is in countries with a very small impact on the planet. By almost any measure you choose, a small proportion of the world’s people take the majority of the world’s resources and produce the majority of its pollution.

Let’s look at carbon dioxide emissions: the biggest current concern because of climate change. The world’s richest half billion people—that’s about 7 per cent of the global population—are responsible for half of the world’s carbon dioxide emissions. Meanwhile, the poorest 50 per cent of the population are responsible for just 7 per cent of emissions. Virtually all of the extra 2bn or so people expected on this planet in the coming 30 or 40 years will be in this poor half of the world. Stopping that, even if it were possible, would have only a minimal effect on global emissions, or other global threats.

Ah, you say, but what about future generations? All those big families in Africa will have yet bigger families. Well, that’s an issue of course. But let’s be clear about the scale of the difference involved. The carbon emissions of one American today are equivalent to those of around four Chinese, 20 Indians, 30 Pakistanis, 40 Nigerians or 250 Ethiopians. A woman in rural Ethiopia can have ten children and, in the unlikely event that those ten children all live to adulthood and have ten children of their own, the entire clan of more than a hundred will still be emitting less carbon dioxide than you or me. It is over-consumption, not over-population that matters.

Economists predict the world’s economy will grow by 400 per cent by 2050. If this does indeed happen, less than a tenth of that growth will be due to rising human numbers. True, some of those extra poor people might one day become rich. And if they do—and I hope they do—their impact on the planet will be greater. But it is the height of arrogance for us in the rich world to downplay the importance of our own environmental footprint because future generations of poor people might one day have the temerity to get as rich and destructive as us. How dare we?

Some green activists need to take a long hard look at themselves. We all like to think of ourselves as progressives. But Robert Malthus, the man who first warned 200 years ago that population growth would produce demographic armageddon, was in his time a favourite of capitalist mill owners. He opposed Victorian charities because he said they were only making matters worse for the poor, encouraging them to breed. He said the workhouses were too lenient. Progressives of the day hated him. Charles Dickens attacked him in several books: when Oliver Twist asked for more gruel in the workhouse, for instance, that was a satire on a newly introduced get-tough law on workhouses, known popularly as Malthus’s Law. In Hard Times, the headmaster obsessed with facts, Thomas Gradgrind, had a son called Malthus. In A Christmas Carol, Ebenezer Scrooge was also widely seen at the time as a caricature of Malthus.

Malthus, it should be remembered, spent many years teaching British colonial administrators before they went out to run the empire. They adopted his ideas that famine and disease were the result of overbreeding, so the victims should be allowed to die. It was Malthusian thinking that led to the huge and unnecessary death toll in the Irish potato famine.

We must not follow the lure of Malthus, and blame the world’s poor for the environmental damaged caused overwhelmingly by us: the rich. The truth is that the population bomb is being defused round the world. But the consumption bomb is still primed and ever more dangerous.

Fred Pearce is author of Peoplequake (Eden Project Books)





Read what James Lovelock, Bjorn Lomborg, Ed Miliband and many other experts have to say about climate change in Prospect’s Copenhagen special