This question is really important for us at Lowimpact.org, because we’re all about providing information and other resources on ways that people can live in a less environmentally-damaging way. So I was very interested to see that researchers at Lund University in Sweden recently put the hours in to get figures alongside the various things that you can do to reduce your impact on the environment.

The figures they came up with were tonnes of carbon dioxide equivalent per year that could be saved by giving up a certain activity. This means the effect on global warming of the emissions associated with the activity, but translated into the effect that carbon dioxide would have. So for example, if the activity involved releasing methane, the figure would have to be increased, because methane is a more potent greenhouse gas than CO2, and so more CO2 would have to be emitted to have the same effect.

Carbon emissions aren’t the only thing that are damaging the biosphere, but they’re certainly important, and so I was very curious to see what the most effective actions might be to reduce them. I thought it would be close, and that the candidates would be driving, flying, eating meat, living and working in concrete buildings, waste generation, energy use etc. But I was wrong, apparently – it was none of those things, and it really wasn’t close. The most damaging thing that anyone can do causes more (several times more) carbon equivalent emissions than all the other activities mentioned combined.

The ‘winner’ was the cute little elephant in the room – kids. Having an extra child is the most environmentally-damaging thing that you can do, by a long, long way. An extra child means on average, an extra 59 tonnes of CO2 equivalent per year. The next largest figure was for having a car, 2.4 tonnes; then flying (although just one transatlantic flight per year), 1.6 tonnes; and eating meat, 0.8 tonnes. The figure for the extra child is so high because all the things that we do as individuals are doubled, as there’s another person to do them – and that person could well go on to generate more people, and so on. The argument often put forward by environmentalists – that they’re going to educate their little darlings to live sustainably – doesn’t wash because a) there’s no guarantee (at all) that children are going to have the same values as their parents, and b) how many Western young people don’t fly, drive or consume many times more than the average Indian or African?

This research reflects the fact that we ourselves are the source of the ecological damage causing the current wave of extinctions that threatens our future, and therefore every extra human on the planet exacerbates the problem. Every other species is forced to live in harmony with its environment because overpopulation will very quickly be accompanied by a reduction in the species that it eats and an increase in the species that eat it – which will mean that its numbers fall back to sustainable levels very quickly. But humans don’t live by the same rules. For a start, nothing eats us – well, not regularly, anyway. No-one really expects to end their life by being eaten by a predator. And we’re not restricted by a reduction in locally-available food when our numbers increase, because we’ve developed technologies to help us get food from elsewhere, at a rate that nature doesn’t usually provide. We trawl oceans all over the world; we spray chemicals to kill ‘weeds’; we add petrochemicals to the soil to increase short-term fertility; we clear forests to produce more agricultural land; and we poison, trap and shoot any wildlife that has the temerity to try to grab a share of our crops or livestock.

This means that our numbers are not limited locally, and that millions of humans can live in cities in deserts or other areas that produce very little food – because that food can be shipped in from the other side of the world. But it also means that the biosphere is slowly being degraded globally. Look outside your door and you’ll see grass and trees, and hear birds singing (if you’re lucky), and so for a lot of people, there really doesn’t appear to be any problem, environmentally-speaking. But listen to ecologists (which most people don’t), and you’ll understand that damage to the global biosphere, unless stopped, is going to mean the end of us.

Now I’m assuming that the study isn’t meant to make us want to stop having kids altogether. Two kids per woman will at least ensure that we continue as a species. But if the global average is more than two, that’s not sustainable either. In the long term, we have to hover around the two-kids-per-woman mark – too few and we start to disappear; too many and we undercut our life-support system. However, at the moment, an extra child in a Western country will have a much greater effect than a child in sub-Saharan Africa, because the Western child’s consumption will be so much higher.

The topic appears to be taboo for a lot of environmentalists, who prefer to focus on the effect of attempting to achieve perpetual economic growth on a finite planet. And they’re right – the world could (possibly) cope with 20 billion people if we all lived like the average Tanzanian; but perhaps only one billion if they all wanted to live like the average American. It’s what that extra child will consume in its lifetime that’s the problem, not its mere existence – although there are some basic necessities required to keep anyone alive at all.

For example, George Monbiot says that focusing on population is just shifting the blame for ecological damage from rich to poor. Population growth is highest in poor countries, and so this makes them a handy scapegoat, while we in the West continue with our high-consumption lifestyles. He’s right about that, but what he misses is that fact that people in poor countries don’t want to stay poor – they also aspire to high-consumption lifestyles. Tanzanians want to live like Americans, not the other way round. As the flow of people from rural to urban in Asia accelerates, and the overall population increases too, a network of megacities of over 30 million people is developing, all of them geared to maximise consumption and growth. The real ecological damage associated with overconsumption is yet to happen, and it’s difficult to envisage how a booming human population and a dwindling nature can co-exist. It’s a struggle that one side has to lose, and in the long-term at least, it won’t be nature.

Having said all that, human population increase is slowing down as birth rates fall, and the number of humans should stabilise before the end of this century. Economic growth, however, is being chased by every government on the planet, and represents a far greater threat, utlitmately, to our survival – mainly because so few are questioning it (and virtually nobody in positions of power).

Apart from environmentalists who would rather focus on economic growth than population growth, most people who are vehemently opposed to population control also argue that we’re not damaging the biosphere at all – or at least not to the extent that we should be worried. They tend to be corporate apologists, and frankly, they’re cretins. Their arguments can be torn apart in seconds by anyone with an internet connection and an IQ higher than their shoe size. Sorry to be so blunt, but arguments that we are not damaging nature are ideological, intellectually on a par with young-earth creationism, and not something we need to get embroiled in. Just point to the science.

Population is falling in some countries, where birth rates per woman are below (and often well below) 2. For example, Germany (1.44), Japan (1.41), Poland (1.34) and South Korea (1.25). But the global figure is still around 2.3, and in sub-Saharan Africa, it’s closer to 5, and not really falling very much at all. The population of Africa is 1.2 billion, but it’s projected to more than double by 2050, and not to stabilise until it’s closer to 4 billion (which is more than half the current world population). At the same time, deserts are advancing at around 5km per year in West Africa, half of its 220 million hectares of agricultural land is losing at least 30kg of nutrients per hectare per year, and 80% of its farmland is experiencing soil loss, which means that per capita food production in Africa is declining. I’ll let you try to imagine what booming population, desertification and declining food production is going to mean for Africa and for the world.

A few other thoughts:

1. ‘You can start by committing suicide’? Possibly the stupidest response imaginable to any mention of population control, and yet (online at least) a very common one; population reduction (or at least stabilisaton) is (of course) about having fewer kids, not killing people who are already alive.
2. Environmentalists with lots of kids? Difficult to square this one, I think, as an extra child (i.e. over and above the two that will replace you) will wipe out every single thing you try to do to live sustainably.
3. Adoption rather than fertility treatment? There are apparently over 150 million children without parents worldwide, so why the boom in fertility treatments? Do people find it difficult to imagine loving something that doesn’t share their genes? Or do people think that their genes are so special that they absolutely have to be passed on to the next generation?