In any debate there are particular key arguments that are used to undermine the opponent. A debate as heated as that over the importance, or not, of population growth is sure to feature these. It should be clear to readers of my essay published last week that I regard population growth as the core issue in any discussion on sustainability. Many of the arguments used by those who wish to dismiss or lessen the importance of population growth are false, misleading or simply mental tricks allowing their advocates the comfort of self-deception.

Some of the main arguments refuting population growth as a problem are:

Consumption growth is more important than population growth

This argument is based on the idea that humanity’s impact on the environment is the product of both population size and the amount that each member of the population consumes (consumption per capita). Impact increases both with increasing population numbers and increasing individual consumption. We can have more people without increasing the stress on the environment if each person consumes less. Alternatively we can have more consumption per person but not increase our environmental impact if we reduce the number of consumers (i.e. the population).




Unfortunately we live in a world where most people consume very little (i.e. are in poverty) but want to consume more and where a privileged few (the industrialised nations) consume relatively huge amounts and will not willingly consume less. If an average citizen of Bangladesh moves to Australia then their environmental impact (ecological footprint) will increase by 13-fold. This is the same as giving birth to an additional 12 Bangladeshis (who remain in Bangladesh). Thus, it is true that consumption growth can have an impact that is equal to or more than the birth of an extra individual if that additional individual is poor.

However, there is one very important difference between growth of consumption and growth of population. Consumption growth is easily reversible but population growth is not. In other words, in a crisis where a resource (for example, energy) becomes limiting it is far easier to reduce use of that resource by reducing per capita consumption than it is to reduce it by reducing the number of consumers.

This may seem like a theoretical point but it becomes very important when efficiency gains are being used to allow continued population growth. For example, in the city where I live, Adelaide in South Australia, we are in a severe drought and we are all being encouraged to use less water. Our gardens are dying and it is difficult to grow one’s own food when watering is only allowed with a watering can and even that may be banned if things get worse. Obviously, Adelaide has reached the limit of population that is sustainable at current standards of living and that limit is set by the particular critical resource that is currently least available - water. However, the government has a plan to increase Adelaide’s population by 50 per cent by 2050. The only way they can do that is by making each person use water more efficiently and by using energy- and technology-intensive desalination to generate additional water (although the energy crises anticipated before 2050 throw the desalination plant’s future into doubt).

At Adelaide’s current population size there is obviously some degree of reserve capacity in our water use that allows us to continue to perform essential functions despite reducing consumption (if we do not regard keeping our gardens alive as important). The drought conditions have forced us to reduce consumption but we still have enough to survive on.

However, we can only increase our population if the current lower (more “efficient”) consumption levels are accepted as the new norm. If we now increase our population to the limit allowed by the new norm then, if the drought worsens, we will have to reduce our water consumption per person further but this will not be as easy to do as previously. There is, after all, a lower limit to the amount of water per person that we can consume and still have a functioning society. As we get closer to that limit it becomes harder and harder to reduce water use and so we become more and more vulnerable to the effects of reduced water availability.

In fact, a society operating at the maximum level of efficiency with respect to an essential resource (such as water, energy, phosphate and so on) is very vulnerable and will collapse if the essential resource is restricted further. To be truly sustainable and secure a society must operate well within its resource limits. In fact, the security and sustainability of a society is reflected by its capacity to waste resources. (This does not mean that it should waste resources, only that it has the capacity to do so if it wishes.) After all, one can only waste resources when the reserve capacity to do so exists and it is this reserve capacity that is the true measure of “sustainability”.




I should perhaps point out briefly that “sustainability” is, of course, a time-dependent concept. At any instant in time, everything is sustainable or it would not exist. When thinking of environmental impact sustainability is commonly used to mean the ability of an activity (such as a civilisation) to persist for a long period (indefinitely). Maybe if the environmental movement adopted the word “persistence” it might focus people’s minds more on the long-term survival of our society and be less prone to abuse by commercial interests wishing to greenwash their activities.

China’s one child policy is a violation of the human right to control ones own fecundity

We need to decide which human right is more important - the right to unrestricted reproduction or the right not to starve to death. People who reproduce at a rate that increases the population size threaten the survival of their own children and the children of all others.

People who oppose population growth are really just opposed to immigration (because they are racist)

Believe it or not, it is actually possible to have immigration without population growth. One simply operates a “one in, one out” policy. Immigrants are only allowed to enter an area if the population is kept stable by the death of inhabitants (without internal replacement) or by emigrants leaving the area. One example of such a policy in operation is for Norfolk Island (PDF 189KB) off the Australian east coast. (It is commonly said that people living on islands have a greater appreciation of the limitations imposed by finite resources.)