Peak population

Fertility policies have failed to win favour among climate-change strategists but lowering the global birth rate is a workable way to cut emissions, argues Sara Parkin, kicking off a series of articles on demography.

At the time of the first United Nations World Population Year in 1974, there were 4 billion of us living on Earth. Today we number 6.8 billion and, according to the UN median projections, will number 9.5 billion by 2050. By the same date, however, we humans are committed to arresting global warming, collectively reducing emissions of greenhouse-gas emissions by 50% on 1990 levels. Yet rarely is the absolute number of people discussed as much as our affluence or our technological prowess in mitigation or (because we have left it so late) climate change adaptation strategies. 

Looked at from an ecological perspective, this is astonishing. We humans are well out of our “ecological niche”, with no other big, fierce, predatory animal claiming a population counted in more than millions (for example, the crabeater seal – a hugely successful species – only has an estimated population of 15 to 40 million). Already we “take” more biological resources from the Earth than it can renew each year and as well as turning carbon dioxide into a dangerous pollutant, we have become the main contributor to the Earth’s nitrogen cycle.

From the perspective of the human economy, however, it seems the more people there are, the better. Today, a successful economy is geared to produce ever more goods and services, requiring not only that today’s adults consume more, but that increasing numbers of new recruits join their ranks. It could be postulated that the model of an eternally growing economy geared to producing more food and more homes for more people began even before we humans took up agriculture. And that as we got better at preventing death – but invested vastly less in preventing births – the model “turned” and became omnivorous, consuming unsustainable volumes of resources and exploiting millions of people just to maintain growth of “consumable” goods and services. The environment and people now serve the needs of the economic model, rather than vice versa.

But nothing can grow forever. US economist Herman Daly points out that a tree, once mature, starts to give things back to nature and that, unless we can find a human economic model that does the same, disaster is certain. Such a model would certainly involve countries going through some sort of ecological demographic transition, where population numbers fall and eventually settle at a lower level, with recruitment equalling loss. Morally, we have to do this in a planned way, because if we don’t, resource constraints or climate change will do it for us brutally.

Already, the growth in the global population has slowed, with average fertility rates halving from five children per woman (cpw) in 1950 to 2.5 today and, in several countries, the ecological demographic transition is clearly underway, notably in Italy and the former Russian Federation where the fertility rate is under 1.4. But even though fertility rates are under replacement levels in countries as different as Brazil and Iran (1.7 cpw) and China (1.8), in many countries they are not, such as Ethiopia (4.8), the United States (2.02), Bangladesh (2.2), India (2.5) and Mali (5.7). The inbuilt increase of women of child bearing years, however, means world population is still growing at around 80 million a year, putting world population on target for the United Nation’s higher projection of over 10 billion by 2050.

So what needs to be done? From an ecological perspective, the further under the lower UN projection of 8 billion by 2050 global population comes in at, the better. Given the disparities in resource use and greenhouse-gas emissions (for example, the United States produces 24 tonnes of CO2 equivalent per person per year, China 5.5 tonnes and Ethiopia 1 tonne) preventing births in America would seem to give the best returns to the environment.

This argument, promoted by some development experts, has a perverse logic that says it is alright to have large families as long as you stay poor. The truth is that this is a challenge for both rich and poor. For example, even though China is on the world average for emissions per person, the size of her population means she is roughly on a par with the United States for total emissions. And although India’s greenhouse-gas emissions are 1.7 tonnes per person, her projected population increase by 2050 will mean a rise from 370 people per square kilometre to 490. Moreover, the additional benefits to poor women in charge of their own fertility – in health, education, ability to help their children thrive, contribution to environmental protection and food security for example – are well documented. See, for example, the 2008 and 2009 reports from the UN Family Planning Association (UNFPA).

The collective effort to reduce greenhouse-gas emissions distinguishes between countries with different emissions levels. The United Kingdom, for example, aims to reduce its current 11 tonnes per person emissions by 80% by 2050 as its contribution to the collective global target. Other contributions to keep the global population under 8 billion could follow a similar pattern. That global target means each woman having, on average, one child less. As fertility rates in many richer countries are stagnating or even slightly increasing, paralleling the justice built into variable contributions to reducing greenhouse-gas emissions would mean richer countries trying to meet or beat that average, while also ensuring the necessary investment to help poorer women halve their family size and feel confident the children they do have survive and thrive. Popular family-planning programmes in remote areas of Mexico, for example, pack contraceptives and vaccines onto the back of the same donkey.

Climate-change talks may be in the doldrums, but there is no reason for delay in realising the contribution 1.5 billion fewer people could make to greenhouse-gas emissions and to the overall welfare of women and children as well as local environmental and economic resilience, especially – though not uniquely – in the poorest countries.

It is estimated that well over 300 million women worldwide want contraceptive materials and advice but have limited or no access to them. Even in rich countries, 30% to 40% of pregnancies (in and out of marriage) are unplanned. Meeting these unmet needs should not be difficult, and is one of the more competitively priced strategies for reducing greenhouse-gas emissions.  

Policy resistance to considering population policies in the context of sustainable development has several causes. The first is the implication of fewer people consuming less for an economic model perversely constructed to thrive on the opposite. The second is the diffidence of policymakers when it comes to anything to do with sex. And the third is the bad reputation family planning gained from past heavy-handed programmes carried out by international agencies and in China and India. 

But as the soaring demand for food, water and energy is exacerbated by climate change, it is no longer legitimate to leave policies for lowering birth rates off the policy agenda. Adding family-planning information and materials to the list of fundable technologies for climate mitigation and adaption post-Copenhagen would be a good start. Moreover, there is no reason to wait until an international agreement is reached. Rich and poorer countries alike can simply get on, put their own houses in order and help others to do the same. For example, in its recent publication “Growing Pains, sustainable development charity Forum for the Future has made recommendations to the UK government on better ways to address population.

In the end, family planning is the responsibility of all of us, at an individual as well as at a global level. A 50% reduction in greenhouse-gas emissions by 2050 means we have to use fewer resources than we do now by an order of magnitude – on top of being ultra efficient in what we do use. Not one or the other, but both. As world-renowned environmentalist and broadcaster Sir David Attenborough points out: “I’ve never seen a problem that wouldn’t be easier to solve with fewer people, or harder, and ultimately impossible, with more.”


Sara Parkin is founder director of Forum for the Future. This article is based on parts of her new book The Positive Deviant: Sustainability Leadership in a Perverse World. To order the book with a 20% discount, enter code PD20 in the voucher box when you order online at

Homepage image from