By John Guillebaud | 10 June 2014

Ockham’s Razor

Many years ago, as a second year medical student, I attended a lecture on human population by my tutor at Cambridge, Colin Bertram. He argued as a biologist that relentless population increase by any species is always ultimately unsustainable; numbers increase to the limits of the carrying capacity of their environment and when they overshoot this, their numbers always collapse. If we allow unremitting population growth to continue we humans cannot escape the same fate; however cleverly we might adapt to all the different environments on earth, we only have one finite planet to live on and 70 per cent of it is salt water, and half of the remainder is desert, mountain, icecap or fast-disappearing forest.

Dr Bertram’s lecture startled me and established the direction of my medical career. I felt some guilt that doctors had inadvertently caused the population problem through vastly better death control while birth rates remained high. I decided that, as an about-to-be doctor, I should try to restore balance, and what more appropriate medical specialty could there be than family planning? So I arranged higher training in gynaecology (specialising in hormonal and intrauterine contraception) and also in surgery (hence my career total of 5000 vasectomies and ongoing research into a new male pill).

None of us in those days was worried specifically about climate change. As we’ve just been reminded by the Intergovernmental Panel on Climate Change, that environmental problem is terrifying enough, especially given the risk of runaway positive feedbacks, caused, for example, by methane release from permafrost. Even so, that is far from being the only life-threatening global problem. The UK government’s chief scientist and the last president of the Royal Society have highlighted the imminence of a ‘perfect storm’: water, food and fossil fuel scarcity. Reliable reports on the planet’s health such as The United Nations’ Global Environment Outlook have found water, land, plants, animals and fish stocks are all ‘in inexorable decline’. Already by 2002 it was calculated that 97 per cent of all vertebrate flesh on land was human flesh plus that of our food animals (cows, pigs, sheep etc), leaving just three per cent for all wild vertebrate species on land. Not to mention the obliteration of wild life in the oceans through acidification, pollution and massive over-fishing.

Regarding human numbers there is some good news: the total fertility rate or average family size of the world has halved since 1950, when it was over five, to about 2.5 (where 2.1 would be replacement level). The bad news is that despite this, the 58 highest fertility countries are projected to triple their numbers by 2100. In a majority of all countries there is also persistent population momentum created by ‘bulges’ of young people born in high fertility years.

Therefore, the UN warns bluntly that world population, now well over seven billion ‘has reached a stage where the amount of resources needed to sustain it exceeds what is available’. The annual population increase of over 80 million equates to a city for 1.5 million people having to be built, somewhere, every week—with, inevitably, ever more greenhouse gas emissions and the continuing destruction of forests and wetlands, with their multiple habitats for the web of life on which all species depend.

This is not exactly a bundle of laughs, yet it is solidly evidence-based, as any impartial scientific observer will attest. Those who are not so impartial routinely prefer to ‘shoot the messenger’ or behave like an ostrich.

The Worldwide Fund for Nature calculates that by 2050, humankind will need 100 per cent more of the planet’s total biocapacity (forestry, fisheries, croplands) than there is. What are the prospects of finding another planet for humans to plunder by 2050? On a finite planet sustainability is not an option, it’s just a matter of how it is achieved. Will the imbalance be corrected by literally billions of deaths or by fewer births? How strange, given the evidence, that population growth and contraception remain largely taboo.

Those who consume way beyond their share, the rich over-consumers in every country, must certainly massively reduce their environmental footprints, but the ‘number of feet’ is also relevant. Often statements like this are assumed to refer to the poor, but our organisation, Population Matters, stresses that affluent parents must also seriously consider having one less child than they may have planned. The guideline is just two for replacement.

All this is hardly rocket science: indeed you could hardly have a better example of Ockham’s razor. Surely, continuing business as usual involves far more unrealistically optimistic assumptions than the precautionary approach. The precautionary approach requires proper resourcing of voluntary family planning services, which still receive a derisory less than one per cent of world aid for reproductive health, and the removal through education and the media of the many barriers that continue to stop millions of women from having the choice to access methods of contraception. This is not an alternative to the other crucial precautionary measure: reducing the size of humanity’s mean environmental footprint. Both are vital; they are two sides of the same coin.

When the camel collapses with a broken back, the last straw did not really do it. It was the fault of all the straws. To achieve environmental sustainability, everyone must be involved.

When a field of common land is right at the point of being over-grazed, Garret Hardin called it ‘the tragedy of the commons’. This is because each herdsman continues to find it advantageous, personally and for his family, to put yet one more cow on the land, and another and another—even if the later new arrivals are thinner and less productive than before—right up to the point that the grazing limit is finally exceeded and all the cows die and all the families suffer. Fishermen behave similarly when there is a nearly over-exploited fishery. Given any resource that is held in common, the private gain of the individual is thus at the shared cost of the whole group, progressively and ultimately catastrophically.

Hardin said the way to avoid these tragedies was ‘mutual coercion, mutually agreed upon’, meaning everyone agreeing to be regulated by peer-pressure, along with agreed fiscal incentives and disincentives. So in the fishery example, each fisherman takes an agreed smaller quota, which is sustainable. However, not every relevant thing that happens in the environmental commons can be so regulated. The multiple decisions made by each individual about cycling or walking rather than going by car, switching off air conditioners or choosing to have a small family are difficult to influence. When push comes to shove—especially when we see so much continuing gluttony in energy use by large corporations—all of us can feel wonder what the point of helping the environment is when it seems like nobody else does.

John Guillebaud is Emeritus Professor of Family Planning and Reproductive Health at University College London.

Stephen Emmott’s Ten Billion, Trailer | The Future of Our Planet

How the world went from 170 million people to 7.3 billion, in one map

Al Bartlett – Democracy Cannot Survive Overpopulation

Sir David Attenborough: an interview with the Wellcome Trust

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