• You are here: 
  • Home
  • Understanding the Dangers of Unlimited Population Growth | Promoting Good Health

Seven Billion and Counting

Posted on December 6th, 2011 by Stephen Hardy | Print

A month ago we hit an important milestone as a species. It wasn’t some startling new discovery, a medical breakthrough or the completion of a massive engineering project. It was a quiet milestone receiving barely a mention on the evening news. Nevertheless, it was highly significant. With very little fanfare, the world’s human population reached seven billion.

No one knows exactly who the seventh billion person to be born was or where or when they were born. So to mark the event, the United Nations chose October 31 as the date and identified babies in various countries around the globe to act as symbolic heralds for the milestone.

How did we get to this milestone? It’s an important question with a very interesting answer.

It took all of human history to reach 1 billion people in 1800.

It was another 127 years before we reached 2 billion in 1927.

It took 33 more years to reach 3 billion in 1960.

Another 14 years to reach 4 billion in 1974.

Only 13 years to reach 5 billion in 1987.

12 years to reach 6 billion in 1999.

And in 2011 – another 12 years later – we passed 7 billion.

Figures courtesy of the United Nations Population Fund (1).

Look at how fast the population is growing. While it took two human lifetimes to go from 1 to 2 billion, it now takes little more than a decade for the population to increase by the same number. In my lifetime, the world’s human population has increased by over 4 billion.

But growth is a good thing, isn’t it? Shareholders want their stocks, investments and superannuation to go up; we want our houses to increase in value; business owners want greater productivity; employees want more take-home pay and economists and politicians constantly tell us we must have a growing economy to guarantee our future prosperity. So an increasing population must also be good? More people to do the work; more people to buy the goods we make and more people to pay taxes and contribute to the economy. So the faster we grow the better off we are, right? While it sounds great on paper, does it really work that way?

Seven billion people, even living modest lives, need a lot of resources. Eight billion people will need even more and nine billion even more again, when we reach that number by 2050 (1). And what happens to the resources we need when the growing population in the third world wants the same luxuries and lifestyle we enjoy in the first world? And who can blame them?

So what human population can the Earth support and how will we know when we get there? Some believe we have already gone past the Earth’s capacity to cope and we are living on borrowed time.

Economists love growth curves and economic growth is the new religion. Biologists, however, see through different eyes. The same graphs that excite economists make biologists very afraid. Why?

At the same time as human population and economic prosperity have exploded, the speed at which the planet is losing other species has grown alarmingly. Something is wrong. The rate of extinction is already over 1,000 times the historical average and shows no signs of slowing down (2 and 3). In the past 500 million years there have been five great mass extinctions of plants and animals on Earth. Many believe humans and human activity are causing a sixth. The scientists Eugene Stoermer and later the Nobel Laureate Paul Crutzen even coined a phrase to describe our effect on the planet: “Anthropocene” – The age of man (4).

This is not mere coincidence. There are numerous examples in nature where the success of one organism or species happens at the expense of others. If a bacterial infection or a cancer goes unchecked it will eventually kill its host. If a predator eats all its prey, it will starve. Nothing in nature goes on growing forever. Nature has ways of restoring the balance, of putting an upstart back in its place. Indeed, unlimited growth does not occur in nature – ever. So while economists are getting excited over ever-increasing growth, biologists are wondering how much longer it can go on. If nature does not allow other species to have unlimited growth, why are humans any different? What makes us so special? Why do we believe the rules of nature won’t apply to us? Some argue it is our birth right. That we have been chosen by either evolutionary superiority or God, depending on your personal beliefs, to dominate and rule this planet and through our ingenuity and technological genius, fulfil our potential and take our rightful place in the grand cosmic order.

To put the arrogance and danger of this thinking into perspective, I need the help of astronomer Carl Sagan. At Sagan’s suggestion, the Voyager I spacecraft, having completed its mission and nearing the edge of the solar system, was instructed by NASA to turn around and photograph the planets of our solar system as it sped off into interstellar space. In the images Voyager I sent back between February and June 1990, 12 years after it was launched, was a portrait of the Earth from 6 billion kilometers (3.7 billion miles). On those images the Earth is less than the size of one pixel. A Pale Blue Dot. Of it Sagan said:


“Consider again that dot. That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every ‘superstar’, every ‘supreme leader’, every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.

The Earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds.

Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.

The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand.

It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we’ve ever known.” (5)


For us, everything that ever was and everything that is, exists on this Pale Blue Dot. So aside from cosmic dust, the occasional passing asteroid and the particles and energy we receive from the sun, what we have now is all we will ever have. No one is coming to our rescue. No one is coming to bring us fresh supplies. No more water, no more minerals, no more continents to discover and no more of the atoms that make up our food, our technologies, our bodies and the air we breathe.

Nature is very good at recycling. In nature, nothing is wasted; everything is re-used. What is the waste of one species is the food or raw materials for another. And because nothing is wasted and everything is recycled, the systems are sustainable. They keep on going, keep on cycling, keep on renewing themselves, over and over again. Our technology isn’t based on the same thinking however. Our technology is based on consumption, not on fair exchange. So while the Earth may seem vast to us, it has limits. And one day, if we continue to grow in number and continue to consume, consume, consume with no thought for the future, we will start to run out of things. Things that give us the standard of living we now enjoy. Things that make our lives comfortable. Things we need to survive. And the more of us there are, the faster it will happen.

Warnings about the danger of runaway population growth are nothing new. In 1798, just as the population was approaching 1 billion, the English scholar, Reverend Thomas Robert Malthus FRS said population growth would eventually outstrip our ability to grow enough food in “An Essay on the Principle of Population” (6). In the 1940’s others revived this thinking, most famously in 1948 with “Our Plundered Planet” written by the long-time President of the New York Zoological Society, Fairfield Osborn Jr (7) and “Road to Survival” written by the ecologist William Vogt (8). It was further popularised and politicised in 1968 by the ecologist and demographer Paul Ehrlich in his book “The Population Bomb” (9) and the 1972 think-tank report “The Limits to Growth” by Meadows and colleagues (10). Most recently in Australia we had the television documentary, “Population Puzzle” by businessman and philanthropist Dick Smith (11).

If these warnings are to be taken seriously, why haven’t we already drowned in the sea of humanity? Why do we keep on going? Keep on growing? Why does our population continue to increase?

The answer lies in human ingenuity. Malthus, Osborn, Vogt and Ehrlich all under-estimated the extent of human ingenuity. Following World War II, the increasing industrialisation of agriculture and the use of artificial fertilizers and pesticides led to the “Green Revolution,” which has fed our ever growing population.

Some, notably the economists Julian Simon and Friedrich Hayek, have argued that because of our intelligence we are separate from nature and population growth is the solution to both environmental problems and resource scarcity because human ingenuity, market forces and technological progress will increase efficiencies and find new ways of doing things. With such ingenuity we can continue to grow, potentially indefinitely (12 – 14).

In the short term, this may be true. The same human ingenuity and technological progress that fed the world through the “Green Revolution,” has also created the high level of affluence and standard of living many now enjoy. Sadly however, this prosperity has not been equally distributed. Over 80 % of the world’s population – 5.6 billion people – currently survive on less than $10.00 per day (15). The inequality of this situation I shall leave for another time.

While it would be easy to believe in a bright future created through similar advances in human ingenuity, it is a deception – a fool’s paradise. What is not obvious – or discussed – or even understood – is the environmental cost of these advances and how much of the limited Earth’s resources we are using up in the process. There will come a time when the environmental impact of more and more people living on Earth will outweigh the economic contribution they make.

There are fatal flaws in Simon’s arguments that our ingenuity and a growing population will solve everything. However, given many still believe in these theories, we need to look at them.

The first fatal flaw is there will always be a technological solution for every problem. While it might be true in the mechanical or physical world, it isn’t nature’s way. Mechanical systems often degrade slowly and give warning of an impending failure. Living systems don’t work that way and often give no warning at all they are about to fail. They adapt, they adapt, they adapt and when they can’t adapt any more they fail catastrophically. A heart attack is often the first sign you have a cardiovascular disease. The problem is 50 % of people die from their first heart attack, so you may never get the opportunity to “fix” it later. And even if you are one of the lucky ones and survive your first heart attack, the damage done may be too great to fix. In the natural world it is better to prevent a problem from occurring in the first place than come up with a solution when the problem is real, scary and in your face.

Unlimited Growth CurveThere is also the question of timing. As the population grows and grows, the size and scale of the population-related problems we have to solve also grow. It means the problems get bigger and bigger. As the rate of population growth increases, it also means the time you have to come up with a solution gets shorter and shorter. Eventually, you need to come up with massive solutions that needed to be in place yesterday. To give the necessary lead-time to deal with the really big issues you need to start putting the solutions in place long before it ever becomes obvious you have a problem. Sadly, we don’t have a very good track record of doing this. One day we will strike a problem so big we either won’t know how to solve it or won’t have enough time or resources left to solve it. And the bickering of politicians and the failure of nations to agree, act on, or even acknowledge the global issues we are now facing does not give confidence. We are facing issues that are bigger than any one country and go across national boundaries. Yet our political system isn’t designed to handle it.

The next problem with technological solutions is one of accessibility. How much high technology can you buy or access if you are living on less than $10.00 a day?

The biggest problem with finding new technological solutions is they only work for technological problems. If the problems are caused by our attitude, then no machine or sophisticated technology will help. “Change your outlook and you change your world” is not a shallow New Age catch phrase. And no machine can do it for you.

The second fatal flaw in the arguments of Simon and his supporters is the belief that anything affecting human affairs always has a higher value than things that don’t. Indeed, Simon was often quoted (and likely misquoted) as regarding human environmental impacts that did not have direct and measurable economic impacts as “trivial”. To believe economic value is the only valid measure of worth or importance is naïve, arrogant and dangerous. It’s also scientifically wrong and a moral obscenity. It ignores our humanity. It ignores our place on the Pale Blue Dot. And it ignores how absolutely dependent we are on the other inhabitants of the Pale Blue Dot if we are to survive. It isn’t called the “Web of Life” for nothing!

Fortunately, later researchers have taken a more enlightened view. In “Collapse: How Societies Choose to Fail or Survive”, scientist and award-winning author Jared Diamond looks at how several ancient societies, considered advanced at the time, collapsed because they ignored their environmental impacts or did not fully appreciate their reliance on a healthy and stable environment for their survival (16).

I have no doubt these ancient civilizations had lots of human ingenuity. But when their ingenuity ran out, so did their options.

No one questioned chopping all the trees down on Easter Island. If anyone did, the decision-makers weren’t listening. And the giant stone statues that still stare out to sea on those treeless islands are all that remain of the civilisation that once flourished there and the arrogance and folly that ended it.

The “We must have growth” mantra of business as usual is not an option. If we keep going as we are and the 9 billion people living on the planet in 2050 all achieve a standard of living to match the OECD nations, we will need an economy 15 times the size of the one we have today and 75 times what it was in 1950 (17). How is this possible on a planet with limited resources? How is this possible when so many of the crucial resources we need are already over-exploited? (3, 17 and 18).

So are Malthus, Osborn, Vogt, Ehrlich, Dick Smith and others wrong? No, the fundamental principals they describe are sound. You cannot have unlimited growth on a planet with limited resources. What human ingenuity has done is buy us time. Without a change of attitude, however, all human ingenuity can ever do is postpone the impending disasters first predicted by Malthus in 1798. It cannot stop them. History has shown us that.

We need to start talking about the “elephants in the room”. The first is population. The second is our relationship to the natural world and how we use the limited resources on it. And the third is our relationship to each other and to ourselves.  We need to start having the debate now, while we still have time to explore options. We also need to involve everyone in the debate because we are all part of the problem and must all learn how to be part of the solution.

With so many “elephants in the room” why aren’t the politicians doing anything? It is likely because these issues are such political hot potatoes. To deal with these issues we will have to make big changes – changes that will affect every aspect of our lives. People don’t like change, especially changes that may directly affect them and their quality of life. The problem with political hot potatoes is they get hotter and hotter. And the longer you leave them, the hotter they become.

Nevertheless, it is a debate we must have. And it is a debate we must have now.

Scientist and award-winning author Jared Diamond says societies choose to survive or fail (16). Our future and the future of our children will be determined by the choices we make. What will they be?


(1) United Nations Population Fund. http://www.unfpa.org
(2) International Union for Conservation of Nature (IUCN) Red List of Threatened Species. http://www.iucnredlist.org
(3) Rockström. J.; Steffen, W.; Noone, K.; Persson, A.; Chapin, F. S. 3rd; Lambin, E. F.; Lenton, T. M.; Scheffer, M.; Folke, C.; Schellnhuber, H. J.; Nykvist, B.; de Wit, C. A.; Hughes, T., van der Leeuw, S.; Rodhe, H.; Sörlin, S.; Snyder, P. K.; Costanza, R.; Svedin, U.; Falkenmark, M.; Karlberg, L.; Corell, R. W.; Fabry, V. J.; Hansen, J.; Walker, B.; Liverman, D.; Richardson, K.; Crutzen, P. and Foley, J. A. (2009) A safe operating space for humanity. Nature, 461 (7263), 472-475, 2009.
Comment in: Nature, 461 (7263), 447-448, 2009.
A more readable critique of the above paper can be found at: Gaffney, O.; A Planet on the Edge. Global Change, 74, 10-13, Winter 2009. Available online at: http://www.igbp.net/download/18.1b8ae20512db692f2a680007163/1376383104139/NL74-web.pdf
(4) Steffen, W., Grinevald, J., Crutzen, P. and McNeil, J.; The Anthropocene: Conceptual and historical perspectives. Phil. Trans. R. Soc. A, 369, 842 – 867, 2011. Full article available online at: http://biospherology.com/PDF/Phil_Trans_R_Soc_A_2011_Steffen.pdf
(5) Sagan, C.; Pale Blue Dot: A Vision of the Human Future in Space. Random House, New York, USA, 1994.
More information on ‘The Pale Blue Dot’ can Be found at:
and here
The cited text, taken from the audio book spoken by Carl Sagan, together with some matching images is available as a YouTube clip at: https://www.youtube.com/watch?v=x2Wi464rp4c
(6) Malthus, T. R.; An Essay on the Principle of Population, 1798.
(Six updated editions were published through his life, the last one in 1826).
Available online at: http://www.esp.org/books/malthus/population/malthus.pdf
(7) Osborn, H. F. Jr; Our Plundered Planet. Faber and Faber, London, England, 1948.
(8) Vogt, W.; Road to Survival. Sloane Associates, New York, USA, 1948.
(9) Ehrlich, P.; The Population Bomb. Ballantine, New York, USA, 1968.
(10) Meadows, D. H.; Meadows, D. L.; Randers, J. and Behrens, W. W. III; The Limits to Growth. Universe Books, New York, USA, 1972.
Two follow up reports have been published, expanding on the original:
Meadows, D. H.; Randers, J. and Meadows, D. L.; Beyond the Limits. Chelsea Green Publishing, Vermont, USA, 1993.
Meadows, D. H.; Randers, J. and Meadows, D. L.; Limits to Growth: The 30 Year Update. Chelsea Green Publishing, Vermont, USA, 2004.
In 2008, Graham Turner from the Australian CSIRO Sustainable Ecosystems Division published A Comparison of ‘The Limits to Growth’ with Thirty Years of Reality, where he checks the predictions made in the original 1972 book.
Available online at: http://www.ecsim.org/Vista/archivos/TURNER%20G%20-%20TLG%2030%20years%20comparison%20to%20reality.pdf
(11) Smith, D.; The Population Puzzle. First broadcast on ABC TV (Australia) in August 2010.
Available on DVD from: http://dicksmithpopulation.com
A companion book Dick Smith’s Population Crisis was published in May 2011. Allen and Unwin, Sydney, Australia.
(12) Simon , J. L.; The Ultimate Resource. Princeton University Press, Princeton, New Jersey, USA, 1981.
(13) Simon, J. L.; The Ultimate Resource 2. Princeton University Press, Princeton, New Jersey, USA, 1996.
(14) Hayek, F. A.; The Constitution of Liberty. Routledge and Kegan Paul Ltd, London, England, 1960.
(15) Shah, A.; Global Issues: Poverty Facts and Stats. http://www.globalissues.org/article/26/poverty-facts-and-stats
(16) Diamond, J.; Collapse: How Societies Choose to Fail or Survive. Allen Lane, London, England, 2005.
(17) Jackson, T.; Prosperity Without Growth. Economics For A Finite Planet. Earthscan, London, England, 2009.
(18) Cohen, D.; Earth’s natural wealth: An audit. New Scientist, May 23, 2007.
Full article available online at: http://www.fraw.org.uk/library/tech/new_scientist_2007.pdf


  1. Posted by Ben H at 12:07 pm on January 11th, 2012

    An excellent and thought provoking post!

  2. Posted by Sonia at 3:19 am on February 4th, 2012

    Your blogs are always thought-provoking and scientifically sound. If only there were more voices of warning out there to compel every person to engage in these necessary conversations! Thank you for your efforts on the world’s behalf!

  3. Posted by Stephen Hardy at 7:07 pm on February 11th, 2012

    Thanks for the kind comment Ben,

    Glad you’ve got your mind working on the Big Picture!


  4. Posted by Stephen Hardy at 7:23 pm on February 11th, 2012

    Thanks Sonia,
    The problems of human population won’t be solved until everyone gets involved in the debate. So Welcome!