Population growth, climate change and sustainability of the environment. Do/should Christians care?

Population growth, climate change and sustainability of the environment. Do/should Christians care?

By John Guillebaud

This is the full article – a shortened version appears in Green Christian – Spring/Summer 2008
Click for notes added in June 2015

About the author. I am, first, a committed Christian and member of the Christian Medical Fellowship (UK). Professionally, I am Emeritus Professor of Family Planning and Reproductive Health at University College, London. Born in Burundi of CMS missionaries and brought up in Rwanda (countries whose poverty and violence in subsequent years have indubitably been exacerbated by the fourfold population increase [1]), a single lecture in 1959 on human numbers and its inevitable impact on the finite planet from my then Tutor at St John’s Cambridge changed the course of my career. I concluded from this a very inconvenient truth, that doctors had been instrumental in generating the over-population problem, by doing a good thing (ie death control , chiefly by the public health revolution of 19 th and 20 th centuries) without simultaneously making a top tier priority of another essential thing: the availability to couples of the choice of voluntary birth control . So I decided, over 40 years ago and probably uniquely among doctors anywhere in the world, to specialise in contraception including surgery (our clinic in Oxford has done >39,000 vasectomies to date!) on environmental grounds.

F amily planning could provide more benefits to more people at less cost than any other single ‘technology’ now available to the human race”. [2]

Human numbers, trashing of the environment and poverty alleviation are linked


Unremitting population growth is simply not an option on a finite planet [3,4,5]. At Jesus’ birth, world population was around 200-250 million. It is now over 6700 million and is on track to exceed 9 billion by 2050.  The annual increment of about 79 million humans per year (all births c 139 million minus all deaths c 60 million) equates to a city for one million persons having to be built, somewhere, every 5 days. This is chiefly happening in the developing world, but poverty cannot be alleviated anywhere without using energy. Since energy mainly comes by burning oil, gas, coal or wood, a moment’s thought will reveal that each of these new cities – actually slums – not only eats up increasingly scarce land (often destroying habitats for other species than ours), but also means a million new makers of greenhouse gases GHGs, every 5 days. Nowhere near as much per person as we in the affluent world of course, but when (as in India and China) there are very large numbers seeking to get out of poverty – which is their right – the global impact is large and becoming very scary. In summary, climate change is very much linked to the number of climate chang ers [5] . Moreover shortages of water and now increasingly of food are primarily caused by ‘longages of people’ (too many needing the resource).


Since Malthus first highlighted population in 1798, humans have multiplied sevenfold. We have appropriated for our use virtually the entire planet, but it has limits: 3/4 is salt water and half of the rest is deserts and mountains. As all species learn, when you multiply beyond the capacity of your environment you reach the buffers. Unprecedented global disasters loom and we are the problem:

. the rich, because of our reasonable desire to stay out of poverty – though we over-consume per capita and that MUST change – multiplied by the increasing numbers of us and

. those of us who are poor, because of our equally reasonable aspirations to leave poverty – which can only be done by consuming more than now, meaning with existing technology producing yet more GHGs per person- multiplied by even greater numbers of persons.


Economists thought we had ‘disproved Malthus’ through Norman Borlaug’s green revolution, which ushered in a spectacular increase in food production. Yet that improved technology was and is wholly dependent upon fossil fuels for fertilizers, tractors, and transport. When our fossil fuels are gone, there will be a vast surplus population whose energy needs Earth will no longer be able to supply. Though it cannot help those already here, family planning can still minimise the number of new arrivals that must produce additional GHGs as they rise from poverty.


Borlaug was well aware of all this: in his Nobel Prize acceptance speech he talks of the Population Monster and – speaking in 1970 – he even predicted the 3 decade timescale before despite his best efforts it would be biting back!


The Population Monster

The Green Revolution has won a temporary success in man’s war against hunger and deprivation; it has given man a breathing space. If fully implemented, the revolution can provide sufficient food for sustenance during the next three decades. But the frightening power of human reproduction must also be curbed; otherwise the success of The Green Revolution will be ephemeral only. [6]


Biodiversity [7]

Today, according to the Global Footprint Network, out of all the vertebrate flesh (biomass) there is – 97% is human bodies plus the biomass of our cows, sheep, pigs, goats: leaving just 3 % for all the big game, indeed all other wild species on land [8]! As soon as 2025 our species is on track to have eliminated an estimated one-fifth of all the world’s life forms – a mass extinction of God’s creation-work. Most of this destruction is not so much wanton as thoughtless. It occurs through competition from sheer numbers of humans, leading to massive destruction of habitats (wetlands, woodlands, coral reefs) for other species.



There are only three available [9]:

1 Better technology, for energy, among many other related environmental challenges. Yet all the known renewable green energy sources (including wind, waves, tides, solar and biological) have snags:

•  they have their own adverse impacts (eg biofuel production using cropland and raising food prices)

•  they are plagued by intermittency: the sun may not shine, the wind may not blow

•  they are seriously deficient in power density so simply won’t deliver the profligate energy requirements of modern fossil-fuelled suburbia . Most utilise the sun’s energy as it arrives each day, unlike fossil fuels which provide energy that was concentrated over aeons of geological time.

No way can we rely solely on generating ever more energy from green sources, vastly increasing energy efficiency will be crucial (starting by properly insulating all buildings and forsaking cars wholesale for cycles and trains).


‘The very greenest energy is the energy you don’t use’


2 Reduced consumption . Since technology will not suffice, all Christians should ever more vigorously campaign for this vital solution in the Northern industrialised countries. Their (our) collective track record is dismal, to put it mildly. Some of us consider that since we are not all doing enough, and seem unlikely ever to do enough, voluntarily, rationing of crucial resources – as in time of war – should start now.



Figure 1


Indeed globally per-person consumption is actually certain to go the wrong way – UP: wrongly , through the already affluent not sufficiently reducing their per person consumption, but also rightly – as a human right indeed as an inevitable consequence of poverty relief for the poorest.


3 Fewer humans doing the consuming

If solution 1 cannot suffice and if solution 2 cannot be permitted to be fully effective since that would condemn the poor to unending and utterly unacceptable poverty (2.8 billion already living on less than $2 per day), what else but this solution remains? Since no-one has yet identified any other factors than these three that affect humanity’s environmental IMPACT, it seems odd to say the least that the only one left ‘Population’ is so neglected. Should not Christians like readers of this journal, worried about the disastrous future that looms for God’s green planet, therefore have a far more positive view on family planning?   Voluntary, available and accessible contraception is not a substitute for reduced per-person consumption assisted by technology: it’s just the much neglected other side of the same coin (Figure 1).


Yet in my experience both outside and especially within the Christian Church, highlighting population is largely taboo, it is the “elephant in the room that no-one talks about”; leave alone any talk about the vital importance of promoting contraception – always (in Jonathan Porritt’s words [10]) wisely, democratically and compassionately.



Sustainable Development – vicious circle or virtuous spiral?

Birth rates and average family sizes are declining in most countries, fortunately – small thanks to many vocal but sadly misguided opponents of voluntary family planning. Yet population growth continues. Why? Because of ‘demographic momentum’ [5], due to the large ‘bulge’ of around 2.5 billion who are teenagers (approaching 50% in many African countries. Hence nearly all of tomorrow’s parents are already born, so numerous that if their average family sizes were improbably to average two, population growth (despite the ravages of AIDS) would not cease until a total of about 9 billion was reached. This increase of 2.5 billion is more than the total population of the world as recently as 1950 [5]


By 2050, on current per-person consumption trends – according to the latest Living Planet Report [7] – circa 9 billion people will require over 200 percent of the biological capacity of the planet (meaning its forests, fisheries, croplands etc). This equates to humankind needing another planet! Or will half the population (4500 MILLION people) have to die? Because on a finite planet, t he choice about achieving stability is not whether? but when and how?


Is it to be through the benign route of voluntary contraception? or the only other option, a gigantic cull of half of humanity by the “Natural” causes: violence as humans fight over the last gallons of water or of oil; viruses such as HIV/AIDS and new strains of influenza; or sheer lack of victuals – all exacerbated by floods and droughts through climate change?


Mahatma Gandhi made two linked statements:

“The world has enough for everyone’s need

But not enough for everyone’s greed”


Gandhi’s second statement remains totally valid! Another version of it is: “let us learn to live simply, so that others may simply live”; and to be fair, Christians are prominent in that campaign. But if Gandhi were alive today and spoke with environmental scientists, I guarantee he would agree that the first statement is fast becoming UNTRUE. Why? Because there will soon be altogether too many everyone’s, for all to live a halfway decent life: as we face the greatest environmental crises yet !


So: we will never meet human needs without stabilisation of human numbers .




“Vicious Circle”














Two assertions are correct:


•  Population increase maintains poverty, [arrow (a) in Figure2], because the finite “cake” of any resource-poor country has to be divided among ever more individuals. Without stabilising the number of persons to share it, an increase in a country’s GDP can mean a fall in per-person GDP or per-person share of the land, where this is the chief resource: as in my home country of Rwanda in the years leading up to the genocide in 1994. Imagine trying to help your country out of poverty if it is India, where there are a million extra Indians ever 20 days. There and elsewhere, population increase keeps wiping out successes in poverty alleviation, whether in agriculture, housing, education and literacy, or healthcare.

•  Poverty maintained increases population, [arrow (b)], because in (rural) poverty, reduction of family size appears disadvantageous: “every mouth has two hands”. The labour of each new child in the family is welcomed, especially in the absence of social security for sickness and old age. High child mortality also tends, unsurprisingly, to reduce interest in birth planning until a relatively high average family size is achieved.

Both these are true [5]!

So what is the way forward? See Figure 3




Figure 3

“Virtuous spiral”














If we fight for

  • social justice (everything required to relieve present poverty including also women’s education and empowerment 11,12) AND

•  birth planning (voluntary, compassionate, available and accessible)

with equal vigour, the vicious circle of Figure 1 can become the “virtuous”, upward spiral of Figure 2. through reducing unplanned pregnancies, there is an incremental reduction in average family sizes, fewer to share the ‘cake’ of each family’s resources, hence less poverty, more children surviving so more acceptance of smaller family size through family planning, and ultimately less population growth. . Therefore

take care of the people and the population will take care of itself”

is a good slogan provided that this “care” is combined with the choice of affordable and AVAILABLE family planning services and supplies.


As Tear Fund said in 1994, ” stop counting people and ensure that people count !” But women are people. So this means removing the many barriers (often introduced by men!) to those women who wish to space or stop their childbearing. The removal of such barriers is the only consistent factor in common between the “success stories” where average family sizes came down rapidly (just as quickly as they did in China, by the way) towards the replacement level of around 2: countries which are as different as Korea, Thailand, Sri Lanka, Cuba and Iran. [5]



Coercion? No. Exclusive of other ways to help the poor? No

Many, Christians and others, continue to portray “any quantitative concern for population as necessarily and intrinsically coercive ” of poor people[2]. Not so. Compulsion in reproductive health, whether overt or covert, is wrong-headed and usually counter-productive anyway. Forget coercion, while we are not adequately doing the voluntary things. We know from large scale social surveys of 240,000 women in 38 countries [13] that it is now a myth that most women in the developing ‘South’ would not accept birth planning. I know a bit about this at first hand, being Africa-born and bred, and can confirm it from talking to women on the ground in Rwanda. We are failing to push at an open door marked “women’s choice in controlling their fertility”. Let’s just ensure that every woman on the planet who at time present wants a modern contraceptive method to be used by self or partner has easy access to it. Doing so could greatly reduce maternal mortality (still one a minute in the world today, you can’t die of a pregnancy you don’t have! and WHO says at least 1/3 of pregnancies were unwanted at conception.) not to mention the disaster of 50 million induced abortions. And to continue not doing so, ie inadequately resourcing that voluntary approach, choice-based with adequate services and maintained supply chain for all is, arguably, the best way to ensure that more future Governments will legislate for coercive birth control..the Chinese way we all rightly reject.


Others distrust this contraception concern as sure to be exclusive – of many other key interventions such as social justice, fairer trade, poverty relief, better education or improved child survival. Not so. Why should not a thinking Christian have deep concern for all these AS WELL?


The stakes are high

Ultimately, there could be unimaginable catastrophes for our descendants. Hence my 2044 Time Capsule [10] project in Kew Gardens, Sydney and other sites around the world, which included an apology to them.

We have not inherited the world from our grandparents, we have borrowed it from our grandchildren[Kashmiri proverb] .


My prayer is that our grandchildren should have no need to accuse us of damaging their ‘loan’ beyond repair.


How specifically should Christians respond?[14]

Christians should be enthusiastic supporters of voluntary birth planning, worldwide: hardly the case at present! They should be at the forefront of stressing that contraception is not just ‘permissible’, it can play a truly positive role within marriage . This does not stop Christians also pointing that it can be negative and even destructive to individuals and society when used outside such relationships, for “recreational” sex.


I further believe that contraception is not only OK by him, it must be squarely within his plans for these times. Contraception, from a truly Christian perspective, should be seen not just as “permissible” for believers but as something to praise God for: a technology that scientists (‘thinking God’s thoughts after him’) have devised in the nick of time, for the better welfare of each child, in African or Asian families where resources are scarce, as well as for the future sustainability of Creation on this finite planet.


Rich Christians in an overcrowded world should also think twice about having large families themselves, given that this will mean their large family will have a larger environmental “footprint” than a small one. It might be salutary for a couple to pray over the possibility of having one child less than their original plans! But this does not force everyone into the same family mould. A gentle decline in total population fertility can be achieved by, as exists in the UK at present, a total fertility rate (equates to average family size) of 1.8 children, which is an average of 18 children in every 20 families. This allows some to have more than 2 children if counterbalanced by others voluntarily choosing to have one or none – as is happening in the UK at time present.


Many non-Christians think that Judaeo-Christianity endorses pronatalism ad infinitum: “multiply .fill the earth” Genesis 1:26,28. Yet Genesis describes God commanding the plants and animals to be fruitful and multiply beforegiving that instruction to us humans. The Creator surely did not and does not intend us to multiply so much that we prejudice the fruitfulness of all his other creatures! This would be contrary to his immanent nature.


Added to God’s omnipotence, omniscience, and omnipresence, I believe there is implicit in the Bible another attribute of our God, namely: omni-common sense! So when he said “Fill the earth” he must have meant just that. Which includes, surely, ” when you’ve filled it, don’t overfill it! cease increasing and live sustainably “.


If obeying the “multiply” instruction would, when combined with vastly improved survival through modern medicine, but without adequate birth planning, lead to human numbers which exceed the carrying capacity of the land available – and so wipe out millions of his creatures including humans – godly common sense says this is hardly obeying his other instruction to us and the rest of creation, to “be fruitful”!



We must, surely, ask ourselves some new questions relating to the two great commandments of Jesus [Matthew 22:37-40]:

First, Love the Lord, your God: are we really doing that, if we do not cherish and care for His creation – just as we would for something made by a human loved one ? Our love for God should surely ensure, inter alia, that there are not more of one species (humans) than can possibly live full lives while permitting the survival of his other creatures.


Secondly: Love your neighbour as yourself: should we not more sacrificially a) love our overseas neighbour but also b) love our future neighbour? Can we do that without doing our bit to ensure there are not altogether so many future neighbours that God’s world becomes uninhabitable? [14]

















1 Gasana J. 2003. http://www.peopleandplanet.net/doc.php?id=1780

2 Grant J. In: The State of the World’s Children 1992; Oxford University Press for UNICEF: Oxford 1993: 58-60

3 British Medical Journal. Over-population, Over-consumption: Special issue to mark the arrival of the 6000 millionth human in 1999 (9 October). BMJ 1999; 319:931-34; 977-997

4 McMichael T, Guillebaud J, King M. Population – the two ‘wisdoms’. BMJ 1999;319:931-2

5 Guillebaud J. Youthquake. http://www.optimumpopulation.org/Youthquake.pdf

6 Borlaug N. Nobel Acceptance Speech 1970. http://www.theatlantic.com/issues/97jan/borlaug/speech.htm

7 www.panda.org/news_facts/publications/key_publications/living_planet_report

8 Wackernagel M. In: The Ecological Footprint 2005. Northcutt Productions for Global Footprint Network, Oakland, Ca 94610, USA. See also www.footprintnetwork.org

9 Ehrlich P & Ehrlich A. In: The Population Explosion. Arrow Books: London, 1991: pp 58-9

10 Porritt J. Letter in support of Time Capsule project. www.ecotimecapsule.com (in description of 10 th Anniversary)

11 Guillebaud J. After Cairo. Br J Obstet Gynaecol 1995; 102:436-438

12 Guillebaud J. After Cairo (Corresp). Br J Obstet Gynaecol 1996; 103:92-93

13 Alan Guttmacher Institute. Hopes and Realities : closing the gap between women’s aspirations and their reproductive experiences. Alan Guttmacher Institute: New York 1995: 1-49

14 Guillebaud J. Triple Helix. Christian Medical Fellowship: London, Winter 1999-2000: pp 4-5  


 Notes for 2015

See Post written in Green Christian in June 2015

See Population Matters for more on these issues

See John Guillebands Environment Time Capsule page



Author: Editor 1 | Date: 14 June, 2015 | Category: Uncategorized | Comments: 1

Comments on "Population growth, climate change and sustainability of the environment. Do/should Christians care?"

Environmentalism and the Old Testament | bibleguides:

July 6, 2015

[…] with the environment (go to the links tabs to find more helpful blogs). For example, this article, Do/Should Christians care, helps reason out why Christians need to get involved and how they can do […]

Add your own comment to "Population growth, climate change and sustainability of the environment. Do/should Christians care?"

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.