16 September 2011

The population debate – A few facts please

Head, Division of Earth and Environmental Sciences, Australian Museum, Sydney

January 2000 © On Line Opinion

The global population is now six billion, having doubled since 1960 and trebled since 1927. While there has been much progress in health and living standards for some, the environmental consequences of this explosive growth are devastating; every minute 27 hectares of tropical forest are cut down, every day possibly 100 living species become extinct, every year 26 billion tonnes of topsoil are lost.

Humans now account for a staggering 40% of terrestrial net primary production. Productive land per capita has fallen by 70% since 1900 and water tables are falling. The quality and quantity of freshwater are often at crisis point and the consequences of the greenhouse effect, while uncertain, may be devastating. The ecological capital that is the basis of life is being depleted. Unless some major reductions in anthropogenic environmental impact occur soon, the writing is on the wall for our children or grandchildren.

These facts have led to international action to slow population growth. The Secretary General of the United Nations, Kofi Annan, said in June that nothing could be more important than helping the world’s people to control their numbers. It now seems possible that the global population will stabilise at about 9 billion. Australia’s growth rate is also slowing and may stabilise below 30 million.

Surely we don’t have a population problem in this huge continent? In fact, we do, but the problem is perceived in diametrically opposed ways by different groups of people.

Business people and some politicians seek to boost our population size. They are driven by fears for national security and a lust for economic growth – populate or perish! Alternatively, many scientists and some community groups seek to stabilise or even reduce our population. They are driven by the documented knowledge of unsustainable ecological degradation caused largely by overpopulation and overconsumption – populate and perish!

What makes me one of the latter is to do partly with facts and partly with values. As for values, I believe that to bequeath a viable life-support system (ie, healthy ecosystems) to our descendants is a responsibility. As well, to maintain biodiversity is intrinsically a good thing. These values are not only personal but are held nationally, being endorsed by the Council of Australian Governments in their 1992 document on ecologically sustainable development.

There are three key scientifically-accepted facts underlying this issue. Firstly, human survival is dependent on biodiversity because it provides life-support (resources and waste assimilation). Secondly, biodiversity is not being sustained, and third, population size is one of the key drivers of environmental degradation and biodiversity loss. Total environmental impact is the product of per capita impact multiplied by population size.

While the population boosters are entitled to their own values, they should be careful to avoid false claims. Some, like the economist John Nieuwenhuysen, still claim that much of the environmental damage was done in the first century of white settlement when the population was much smaller. Hence human numbers aren’t the problem.

The truth is otherwise. The authoritative Australia: State of the Environment 1996 (SoE) report makes it clear that the situation for two key issues – land clearance and water diversion – is worse now than ever before. As much land has been cleared in the last 50 years as in the previous 150 years; and over 80% of the Murray River’s flow is now diverted for human use compared with 15% in 1920. The effects on native fish have been devastating, a problem heightened because over 90% of our freshwater animal species occur only in Australia.

The boosters claim that Australia is a huge empty land and there’s something wrong if we can’t support a greatly increased population, but this is an elementary error in geography. The carrying capacity of a region depends on its productivity, not its acreage. Only 6% of Australia is arable, the soils are shallow and infertile, and rainfall is both poor and variable.

In fact, the basic viability of Australian agricultural practices has been questioned by the Prime Minister’s Science and Engineering Council who said in 1995 ‘Agriculture’s future survival will depend on agricultural producers paying significant attention to sustainability, and fundamentally changing the way they manage the whole farm system’. In 1998, the Council found that dryland salinity affects 2.5 million hectares of land with potential for this to increase to 15 million hectares. Moreover, concerning biodiversity, the SoE report says ‘the situation continues to deteriorate as population and demands on natural resources increase.’ In the words of its Chair, Professor Ian Lowe, ‘There is no prospect – even in principle – of a sustainable pattern of development unless we devise a socially acceptable way of stabilising the human population.’

There is also the claim that we can resuscitate our environment through better technologies and reduced per capita consumption without needing to constrain population. We could, but would we?

Technological possibilities certainly exist but they need to be paid for. For example, the Prime Minister’s Science and Engineering Council found that between 50% and 70% of existing agricultural producers may not have the financial resources to make the fundamental and far-reaching changes necessary for sustainable production.

Reducing per capita consumption is another big ask because it is rising sharply, not falling. For example, in Sydney since 1970, per capita consumption of water, energy and food has risen by 25%, 37% and more than 70%, respectively (SoE report).

To promote an ecologically sustainable future, the SoE report recommended a decision-making model that recognises the economy as a subset of society which in turn is totally constrained by the ecology of the planet. But these constraints are not accepted by the boosters who consider ever more economic growth the holy grail. Growth is even claimed to be necessary for funding environmental protection. Social economist Ted Trainer says this is like an obese person needing to eat more chocolate cake to raise the energy to go jogging to lose weight.

The boosters’ position depends heavily on undocumented assertions that population growth is good for our economy, security and independence. Environmental and other problems can be solved or, as economist Glenn Withers recently claimed, are either ‘wrong’ or ‘myths and frights unworthy of a young, clever and vigorous nation.’

To be credible, the boosters need to support their claims with evidence rather than assertions. They need to show why a much larger population would be sustainable rather than accelerating our well-documented ecological decline. Those in doubt would do well to read Mark O’Connor’s recent bookThis Tired Brown Land. Sifting the evidence, it offers, in Bob Carr’s words, ‘a robust demolition job on all the arguments for population growth.’

This issue is no trivial matter; the future of our children and the natural environment is at risk. It is they who will pay the price for of all this long-term destruction for short-term gain. Managing this risk demands our best scientific assessment, political commitment and informed debate. If you believe the growth boosters, we need at least 50 million to be influential and secure. If you believe the scientists, 50 million of us will blow that future away like eroded topsoil.

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