An open access, peer reviewed, interdisciplinary journal exploring all aspects of the relationship between human numbers and environmental issues.


Population and sustainability: the most inconvenient truth

Aubrey Manning

Aubrey Manning is Professor Emeritus of Natural History at the University of Edinburgh. Always involved with conservation and the environment in the broad sense, he is a patron of Population Matters, was president of the Royal Society of Wildlife Trusts 2006-2010 and Goodwill Ambassador for UN International Year of Planet Earth 2008-2010. In 2011 he was awarded the Royal Society of Edinburgh’s Senior Beltane prize for Public Engagement.

Sustainability is applied anywhere and everywhere now but rarely has a term been used with such imprecise understanding of what is implied. However vague on the details, seeking ‘sustainability’ in so many aspects of human activity represents an important shift in the way we look at the world and our place in it. We may not know what is needed but the very fact that we talk about it reveals a recognition that current trends in how we operate are not going to yield it. We are beginning to accept that human activity is having global effects and impinges on the natural resources available to all of us. International action is beginning and currently climate change is the most prominent issue. Whatever the shortcomings of the recent Paris summit and those that preceded it, they represent a remarkable and consistent global consensus that if we go on as we have there will be severe penalties.

Way back in 1966 I joined the recently founded Conservation Society because as a biologist I was attracted by its slogan: ‘Population, Resources, Environment.’ Public concerns about ‘the environment’ were beginning to grow rapidly, especially around the pollution of soil and water, deforestation and the spread of urbanisation with all its associated infrastructure. So far as I could see, the Conservation Society was the only group which recognised explicitly that the number of humans was a key factor in all these problems. Then, populations were growing rapidly, especially in the poorer, so-called ‘developing nations’ and various initiatives were beginning to attract attention. In Britain the problems were seen almost exclusively as being ‘out there’ in the poor countries, although to its great credit the Conservation Society from its inception argued that the rich nations also had a population growth problem.

The message remained, but gradually the emphasis began to shift away from human numbers per se and towards the impact we were having on the planet. Some of the gloomier predictions, such as the Paddock brothers’ Famine 1975! (1967) and Paul Ehrlich’s The Population Bomb (1968) could be regarded as over dramatized. This was a period of sustained economic growth in the rich world bringing dramatic rises in the standard of living in Europe and North America. The effects soon became obvious, both in the damage caused to the environment and in the gross inequalities in consumption of all natural resources which were developing between the rich and poor nations. Even so, for most it seemed that, as always, the Earth could provide!

In 1972 came the UN Conference on the Human Environment in Stockholm, perhaps the first global recognition of that un-sustainability I mentioned at the outset. This meeting led to the UN Environmental Programme (UNEP) being set up. Twenty years later the meeting was in Rio de Janeiro and further meetings have followed at intervals since. Trawling the web will yield a whole range of reports from the UN and its branches and various development ‘think tanks’ across the years. There were a number of aspirational statements timed around the Millennium. The UN’s Millennial Development Goals (MDG) are from 2000:

1.Eradicate extreme poverty and hunger.

2.Achieve universal primary education.

3.Promote gender equality and empower women.

4.Reduce child mortality.

5.Improve maternal health.

6.Combat HIV/Aids, malaria and other diseases.

7.Ensure environmental sustainability.

8.Global partnership for development.

Each nation has particular targets and is expected to report on progress. There can be no question that the UN and its agencies accept the scale of the problems we face, and that in these aspirations they have ‘hitched their wagon to a star.’ The requirements are gigantic.

We must note that there is no direct mention of human numbers here. There is certainly some mention of family planning provision, but although it is obvious that advances in MDGs 1, 2 and 3 will be most likely to reduce birth rates, we do not find this result identified as an aim in itself. Indeed, population per se was rigorously kept off the agenda in earlier UN meetings under pressure from several powerful religious lobbies. It would not be addressed directly, and even then only in muted terms, until 22 years after Stockholm at the UN Cairo conference in 1994.

Biologists are likely to emphasize that without achieving MDG 7 on the environment the rest will become impossible. Even with the current maldistribution of resources, population problems will not end when growth stops as the Earth is already over-populated. We are grossly out of balance with the life support systems of the planet and effectively living off natural capital of soils, water and biodiversity systems. The balance would be far worse if every MDG were to be achieved and the poor of the world were to achieve living standards even approaching those of a middling rich country.

Whatever the concerns of biologists, progress has to begin from where we are now. While there is persistent recognition that much of human activity across our world is un-sustainable population growth has continued. In the 40 years between Stockholm 72 and Rio+20 in 2012, population grew from just under 4 billion to over 7 billion. However, despite this gigantic change, public emphasis had shifted from population itself to progress on all those other issues listed in the MDGs. There are obvious barriers to our success in achieving the environmental sustainability aspired to in MDG 7, with concern over climate change and the rapid loss of biodiversity currently two of the most prominent.

Why has population growth itself had a reduced profile since the scares of the 1970s? In part it must be accepted that some of the earlier calls for birth control were not well-handled and were easily vulnerable to accusations of neo-colonialism and racism. There were major advances in agricultural productivity involving new food plant varieties, increased nitrogen from cheap fossil fuels, and more irrigation. We did not experience famine in 1975 – at least not all over the world. Nor was there a perceptible explosion from the population bomb. Malthus was dismissed as obviously wrong. In this optimistic mood discussion about human numbers became awkward and seen as harsh and unattractive. Governments in the rich world developed overseas aid programmes and public opinion was generally enthusiastic about helping poor nations emerge from poverty.

In Britain a number of new and highly successful charities became prominent. Friends of the Earth (FoE) rapidly took over from the middle-aged, middle-class Conservation Society which vanished. It retains the earlier body’s emphasis on resources and environment, population is recognised as a factor, but is not directly part of its campaigning.   Other fund-raising charities such as OXFAM, Save the Children and CAFOD, stress only the most directly human-centred MDGs and never mention rising numbers as a problem. Of course, there remain groups which do continue to emphasise the problems associated with population growth and, like the Conservation Society, include the rich world in their considerations. Notable amongst these is the Optimum Population Trust, which metamorphosed into Population Matters, and has become increasingly effective in raising issues in a British and European context.

We are now well into the 21st Century and moving inexorably towards our 8th billion, with UN estimates of future population growth mostly being revised in an upward direction. In Britain, those of us who try to link human numbers to the actions required to achieve the Millennial Goals have come across a new barrier: there is a persistent and powerful dichotomy of views within what we might call ‘the environmental movement’ in the broad sense. If we engage activists in various groups, ranging from popular to academic, to express our concern about numbers, then the commonest response is: ‘It’s not population! It’s poverty, greed, inequality, the position of women etc….’. Such responses often carry the implication that to stress human numbers is somehow offensive, almost as if we blame the countries which are growing for their own predicament. There is an imbalance here which I experience personally, for if somebody approaches me and, for example, speaks of their concern about poverty in Africa, I do not respond: ‘It isn’t poverty, it’s population growth!’. Of course poverty is a huge problem requiring immediate direct action on many fronts. Reduction of the birth rate will offer no immediate relief – it would manifestly not be sufficient – but failing to recognise it as necessary is to pursue an illusion.

Africa is the most relevant example here because birth rates remain so high in comparison with other areas which have seen some remarkable declines. More and more African governments now accept that their population growth is too high and cripples their economic development. There are heroic efforts based locally and supported by outside aid groups and the UN, but they still lack sufficient funding or priority. Infrastructure development, food production and health attract the main attention. ‘Death control’ must always have a high priority, but reducing the birth rate will benefit development in every area and should be linked to overseas aid. Nor is this coercive since every survey shows that there is a huge unmet demand for contraception even before there has been sufficient progress on the empowerment of women. Providing the one will help to accelerate the other and offers extraordinarily good long-term value for money.

However diverse and complicated the contexts in which population growth occurs, it should be recognised as a truly global phenomenon. With every day that passes we add – net – about 200,000 more humans and because of the global age structure (with a great preponderance of young people) there is built-in growth momentum. None of the UN estimates predict stabilisation anytime soon. Could there be a more inconvenient truth?

Global estimates conceal diversity: predictions are that whilst Africa will continue to grow rapidly for decades, Europe will slow and soon begin to decline with birth rates below replacement level. But again there is diversity within Europe, and I want to argue that Britain’s population deserves close attention.

In 1969 the then Institute of Biology ran a symposium and published The Optimum Population for Britain (Taylor, 1970). Over 40 years on I believe it should be remembered as a significant event. Here was a distinguished group including demographers, biologists, medical scientists and economists discussing the future in relation to the number of people in a wealthy, developed Western country. It is no surprise that there was considerable disagreement and several argued that the idea of identifying an optimum population was meaningless: how could any generation decide an optimum for a Britain in which they would not be living? Again, no surprise that the biologists took a more pragmatic approach based around our natural resources in relation to the rest of the world. A poll of the speakers and their audience (mostly biologists) revealed 90% believed Britain, then at 55.6 million, was already overpopulated.

Since then we have added well over 9 million and, whilst population growth slowed during the 70s, it has risen again and is higher now than it was 50 years ago. We are adding nearly 500,000 extra people each year, about half from so-called ‘natural growth’ (the surplus of births over deaths) and half from net immigration. There is certainly no shortage of discussion about immigration, but what I find amazing is that there is no discussion or comment about the actual numbers of people: our population. Even if there were no net immigration Britain would grow by a million every 4 years; is that a good thing or a bad thing? Is it sustainable or are there limits?

Almost invariably when there is any report of some symposium or discussion on a sustainable path for Britain’s future then our population is mentioned but with no further comment: it is taken as ‘a given.’ There may be much advocacy of switching to renewable energy, accelerating house building, increasing food production etc., but no suggestion that we might also limit numbers.

There are always two obvious questions about population growth: first, should we take action at all, and second what could we do? There are many who oppose any attempt to influence numbers directly here or abroad. They argue that pushing for the MDGs will lead to falling birth rates as they already have in parts of south-east Asia and the Middle East. This is all we can or ought to promote, it is politically acceptable and few would dissent even if we do not regard it as sufficient.

When we turn attention to a wealthy country like Britain, densely populated by world standards, the issues are more complex. ‘Growth’ is sought always and everywhere. Of course it is economic growth to which we refer, but historically population growth has gone with it as part of the phenomenal success of the rich world since the industrial revolution. Increased production and consumption by a growing work force has led to increased wealth and living standards with it. Its advantages have gone unquestioned until recently, but the strains are now becoming obvious. However, those of us who criticise the continued pursuit of growth are duty bound to acknowledge the enormous benefits our fortunate part of the human race owes to the growth we have experienced until now.

The rich world continues the pursuit of what we might call ‘Plan-A’ economics as the only way to develop and bring prosperity to all. For all the gross inequalities which persist and the failure of growth alone to address them, it is easy to understand why so many still hold to the faith in Plan-A.

Some 50 years ago the economist and philosopher Kenneth Boulding was reported to have remarked:

Anyone who believes exponential growth can go on forever in a finite world is either a madman or an economist.[1] (United States. Congress. House (1973) p. 248)

Nevertheless there are still many who simply do not accept that there are any constraints on growth that innovation cannot overcome[2]. Population growth fits so easily into such a mind-set especially as it will yield more young producers to offset the ageing populations requiring wealth generation to support them in the future. But then these young will also age and require support from more young, and so on. Such population growth represents an economic Ponzi scheme with no closure. To get beyond this we shall be forced to accept that other things beyond economic growth must be encouraged. The distribution of wealth within the rich societies is the most obvious. If we can reduce inequality then there are many indicators that beyond a certain level material prosperity and quality of life are not closely linked. The measures we have to examine such quality are not yet precise, but surely they must form part of our search for sustainability.

As the Kenneth Boulding quote suggests, it is physical things which cannot grow indefinitely. Ideas certainly can and we shall need much innovation there. We cannot turn around Plan-A economics quickly, but after decades of neglect there are now some prominent economists contemplating an end to material growth and thinking about how to develop economies with a slowly declining population. For the present this is a rich world issue. Economic growth decoupled from population growth is essential for the developing world if any kind of equity is to be achieved.

Britain, already rich (the 5th largest economy worldwide) and densely populated, continues to add people. As Migration Watch (2016) points out, a high proportion of this growth is due to net immigration, a highly contentious topic. I suggest that this does not reflect an inherent xenophobia. We do not resent immigration because it makes us feel crowded, it is because we feel crowded already that immigration is resented.  Several opinion surveys over the past decade suggest strongly that people are indeed concerned about population growth here and abroad. References to ‘these crowded islands’ are common with a number of surveys revealing that a large majority believe Britain would be better with fewer people (Migration Watch 2016a). Now I concede that these may be snap judgements, the implications of which are not thought through, but surely it could be the basis for some new thinking. Yet although our large population is almost invariably mentioned when Britain’s future development is discussed, it remains part of the ‘predict and provide’ policies of our planning agencies. There is never a hint that we might try to influence population as a matter of policy. In part this is because our numbers are supposedly linked to our economic growth (Plan-A will not accept that there are limits), but it goes far deeper than this.

To follow through from that YouGov survey implies that too many children are being born, but such a suggestion remains totally unacceptable. The obvious benefits offered by a Britain with a stable or slowly declining population are familiar (they are well set out on the Population Matters website) but to link them explicitly to family size seems taboo. Universally this is regarded as a matter of intimate personal choice and hence untouchable.[3] Even groups who emphasise sustainability are evasive. Euphemisms creep in. One of the commonest is talk of ‘reproductive health’, which on one definition (derived from various UN declarations) implies, that people, ‘…have the capability to reproduce and the freedom to decide if, when and how often to do so’ (World Health Organization 2015).

This freedom is taken as one of the universal human rights. It is adopted by all shades of politics. However admirable its intent, I believe in the modern world this is a dangerous illusion and in a country like Britain it is downright wrong. Deciding to have a child is not just a personal choice because the state (i.e. all of us) effectively underwrites every such decision. It undertakes to provide an environment in which each child has reasonable life prospects and if things go wrong it will step in with direct help. Thus government has every right to try to influence the birth rate when seeking sustainability.

How could we translate this conclusion into an acceptable policy? After 50 years of concern about population growth I have learnt to suppress any radical thoughts about control. I would regard it as a major advance if government at all levels takes just the first very modest step to accept – explicitly – that numbers count. For example, the Office for National Statistics (ONS) (2016) predicts that by mid-2027 Britain’s population will pass 70 million. What are the implications for our future? Nothing could be more important, for while population growth is a global issue, if a rich developed nation begins to question its own growth it could become a powerful influence. It would really mean that Britain thinks globally and acts locally.

Yet we seem unwilling even to discuss possibilities. It would be easily possible to push for smaller families in an acceptable way if we were open about it. The state supports parenthood and it is right to do so, but from 2017 it will not do so beyond a second child[4]. Why not link this policy explicitly to our growth and to people’s sense of a crowded and unsustainable Britain? This link is particularly important because otherwise restriction of child allowances could suggest a 2-child policy for the poor while larger families for wealthier people are of no account.

For all the concerns about ever growing requirements we have to recognise that our culture remains strongly pro-natalist. Childless couples may, grotesquely, be called selfish and recently a woman who wished to be sterilized as she was sure she did not want children was bombarded by abusive messages (Gee 2015). Children are marvellous, essential and not going to go away anytime soon, but childbirth fills the popular media with perpetual sentimental chatter with so-called celebrity women and their ‘bumps’ displayed for adulation. At the other end of the market, in The Times we find a wealthy middle-class columnist agonising about her coming ‘empty nest’ and whether she was foolish not to have had a third child like some of her friends (Turner 2016). All of this gossipy stuff leaves the impression that one more child is neither here nor there and is always wonderful. We need to move to a mind-set which retains that wonder but acknowledges the truly global impact of growing ever more Britons. ‘Two will do’ and ‘every child a wanted child’ are slogans from the old days of family planning. In contrast a recent study suggests 40% of pregnancies are unplanned (Sedgh et al, 2014) (which of course is not to say that all the resulting children remain unwanted). In Britain these ideas will now have to be shared with the new immigrants who, because they are young and often from cultures which have traditionally larger families, contribute substantially to our rising numbers. We cannot ignore this, but we can try to change attitudes only if such efforts are seen, again explicitly, to be addressing the problem of too many births from all sections of crowded Britain.

I struggle to retain some optimism against a background of evasion and denial. Discussion of how to reduce birth-rates seems completely taboo. Amongst many of the public my comments above will automatically lead to cries of fascist, racist and anti-human. But it is even worse: over the past year or more I have approached five well organised academic/business/political ‘think tanks’ whose aims are to consider all aspects of how Britain should prepare for and adapt to the social and environmental future. They have covered education, employment, energy, food, transport and all aspects of the associated infrastructure. As a biologist, I have suggested in, I trust, moderate and rational terms, that Britain’s population – just the numbers – should come onto their programme. Two groups, reasonably enough, claimed other immediate priorities but three, even after repeated tries, did not reply. I was not even dignified with an acknowledgement. It is all too embarrassing and contentious – best to deny the issue altogether and just soldier on, working round the elephant in the room as best we can.

In conclusion, I have to concede that my prediction for the future is only one of many and has a biological bias. Thus I would hope our very limited number of great grandchildren could grow up in a world that still has elephants and all that their survival implies. There are alternatives: we could just let things go on as now or even concentrate on maximising humans (although they would have to accept many compromises in the way they lived). From a strongly left-wing perspective, in Population and Development (1997) the sociologist Frank Furedi argues that those in favour of population control erode the necessary confidence that we can tackle future problems and fail to accept that human life should always be treated as precious and special. He asks, ‘How can there possibly be too many of us?’ (2007). Any biologist could provide an answer.

Between the extremes there are an infinity of intermediates. At least a much lower population would leave our descendants with some alternatives for their future. As we are set at present we are trudging up a down escalator and we risk the Earth’s life support systems slowly being swept down with us. The technological innovations for recovery which we will need are relatively simple. It is the mindset within us that we must struggle to change and this will not be easy.


‘Go, go, go, said the bird: human kind
Cannot bear very much reality.’

                                    T.S.Eliot, Four Quartets


[1] Attributed to Kenneth Boulding by John S. Steinhart.

[2] My favourite quotation here is the title of a piece in The Times some 3 years back by Mark Littlewood, CEO Inst.of Economic Affairs, ‘Triple the population – we’ll all be better off.’ (2013)

[3] Cynics will note that throughout history governments have not infrequently exhorted people to have more children when the economics seems to require it – as Italy does at the moment (Badshah 2016).

[4] Changes in Child Tax Credit mean that from April 2017 support will be limited to two children.



Badshah, N. (2016) Italy bribes families to have babies. The Times 16 May 2016.

Ehrlich, Paul R. (1968) The Population Bomb. Ballantine Books, New York.

Furedi, F. (1997) Population and Development: A Critical Introduction. Polity, Cambridge.

Furedi, F. (2007) Population Control. [ONLINE] Available at: [Accessed 10 May 2016].

Gee, A., BBC News. (2015) The trouble with saying you don’t want children. [ONLINE] Available at: [Accessed 15 April 2016].

Littlewood, M, (2016) Triple The Population – We’ll All Be Better Off. The Times, 24 June 2013. 0.

Migration Watch. (2016) What is the problem?. [ONLINE] Available at: [Accessed 10 May 2016].

Migration Watch. (2016a) Opinion Poll Results on Immigration. [ONLINE] Available at: [Accessed 10 May 2016].

Paddock, W. and Paddock, P. (1967) Famine 1975! Little Brown & Co., Boston

Sedgh, G., Singh, S. and Hussain, R. (2014) Intended and Unintended Pregnancies Worldwide in 2012 and Recent Trends. Studies in Family Planning Vol. 45 Issue 3.

Taylor, L R (Ed.) (1970) The Optimum Population for Britain. Academic Press, London

Turner, J, (2016) The Living Doll Who Killed Off My Baby Pangs. The Times, 11 February 2016.

United States. Congress. House (1973) Energy reorganization act of 1973. Hearings, Ninety-third Congress, first session, on H.R. 11510 … November 27, 28, and 29, 1973 U.S. Govt. Print. Off., Washington, DC.

World Health Organization (2015) Reproductive Health. [ONLINE] Available at: [Accessed 15 April 2016].