Population and environment – whats the connection?

Australia is a large country with a small population. In 2003 we had a population density of 2.5 people per square kilometre; by comparison, the figure for Japan was 338 people per square kilometre, for the United Kingdom 244 and for France 109. Of the world’s developed countries, only Canada (3.2) and Iceland (2.8) have comparable population densities (Box 1: Trends in world population).

A complex problem

While the global and local list of environmental problems is long and growing, it’s difficult to be certain of the extent to which population growth is a contributing factor. For example, land degradation in Australia is a major concern. Rabbits are a major cause of land degradation in some regions of the country, yet they were introduced to the country by just one person. This is a problem of too many rabbits, not too many people.

Clearly, the relationship between the environment and population is complex. To explore it further, we need first to look at population growth.


Population growth in Australia

Nobody knows how many indigenous people lived here before European settlement: estimates range between 300,000 and 1.5 million. It is known, however, that their numbers declined significantly after the arrival of the First Fleet in 1788.

Related site: AusStats: Population clock
Up to the minute projection of Australia’s resident population.
(Australian Bureau of Statistics)

By 1887 there were probably about 3 million people, of mostly European origin, living in the colonies. Australian Bureau of Statistics figures show that the 1901 census counted 3,773,801 people. One hundred years later, in 2001, the national census tallied 18,972,350 people. The estimated Australian population mid-2004 was 20,111,300.

The human population keeps growing

The human population at the global level has been growing exponentially over time (Box 2: Exponential growth). The absolute number of humans has continued to increase, and the distribution of the population has changed, due to differing birth and death rates and the movement of people from one region to another.

Australia’s population also continues to increase. The three factors which have the greatest impact on the population of any nation are birth rate (fertility), international migration and death rate (mortality rate).

The total fertility rate (TFR) is the average number of children a woman gives birth to in her lifetime. A TFR of 2.1 is considered to be the replacement rate, which is the fertility rate needed to keep the population stable if there is no net migration. Australia’s TFR in 2000 was 1.7. Most developed countries have TFRs below the replacement rate. The 2004 estimate of the world average TFR is 2.8, ranging from 1.2 to 8.

Immigration adds to the Australian population in two ways: firstly, the immigrants themselves; and secondly, their Australian-born children (Box 3: Immigration and population growth). The contribution of net overseas migration to Australia’s population growth has averaged about 39 per cent for the past 25 years. This is projected to increase as the Australian fertility rate decreases.

The age structure of a population can also contribute to its growth. A population with a large percentage of people in the child-bearing years (15-45) will continue to increase even if parents do not produce enough children to replace themselves. This is because there are a lot of young people yet to have children and a low number of old people who will die in the next few decades.

Related site: Australian social trends – population
Fertility, death rate and migration influence the size and structure of Australia’s future population.
(Australian Bureau of Statistics)

The combination of birth rate, migration and death rate affects both population size and the age profile. Australia’s population is steadily ageing. Over the next few decades in Australia, the number of people over 65 years of age is predicted to increase, and children will make up a smaller proportion of the population. Population ageing is mostly due to falling fertility rates and increasing life expectancy. An ageing Australian population has economic and social consequences.


Our consuming passion

Although some aspects of the Australian environment are in relatively good condition, Australia has many environmental problems: land degradation, endangered species, an increasing incidence of toxic algal blooms in our rivers, declining fish stocks, land clearing, air pollution, and vulnerable water supplies. There are more, but that will do for a start.

Many environmental problems can be attributed to poor management techniques, policy failure or even feral animals. Such factors are largely independent of population, but the sheer number of people can also contribute to the problems.

Consider, for example, the issue of consumption of material resources. On average, Australians have become steadily richer over the last few decades. As monetary wealth has increased, so has consumption. As a nation we now own more goods, use more energy, eat more processed food and have larger houses than ever before. All this consumption can create environmental problems. In effect, the populated areas of Australia are a sink for natural resources, draining the continent of nutrients, minerals and water. What we don’t consume we export, generating revenue which we use to buy consumer items from abroad. High levels of consumption help to deplete our store of resources, generate waste and increase the stress on the natural and agricultural environments.

The environmental impact of copious consumption may not be confined to the local area. For example, the use of fossil fuels for energy in Australia can have an impact on global carbon dioxide levels and resulting environmental effects.

When Australian consumption is viewed from a global perspective, we leave a large ‘ecological footprint’. The ecological footprint is a measure of how much productive land and water is needed to produce the resources that are consumed and absorb the wastes produced by a person or group of people. In 2001, there were 1.8 hectares of globally productive land per person. In 2004 Australia’s ecological footprint was calculated at 7.7 hectares per person (among the world’s top four resource-consuming nations) compared to the average global footprint of 2.2 hectares. Clearly, the consumption of resources at current levels is not sustainable.

The limits to growth

Some economists have described humans as the ‘ultimate resource’, because they can turn previously useless things into resources by being intelligent, adaptable and creative. Much of what we value and what makes life enjoyable is the product of human endeavour. However, something good can become a problem when in excess – when there is ‘too much of a good thing’.

Factors such as population growth, population distribution and migration combine with high-consumption patterns to put stresses on the environment. There is a limit to the environment in terms of supply of resources and the ability to absorb waste products. Examples include the rate of tree growth for timber harvesting, the available fresh water for irrigation and human consumption, and the time required for the recycling of organic waste. Land degradation, loss of forest cover, pollution of water and air, soil erosion and loss of biodiversity are all occurring at a fast pace, and are evidence of the impact of an increasing population on the environment.

Population and the environment

The maximum number of a particular organism that an environment can maintain indefinitely is often referred to as its carrying capacity. How do we calculate the human carrying capacity of the Earth? We can’t do it by numbers alone because the relationship between population and environment is neither simple nor straightforward.

To come up with the best solution, insights and ideas need to be drawn from many disciplines. These include, but are not limited to, environmental science, geology, economics, demography, human biology and health, geography and political science. The future of both the global human population and the global environment relies on bridging disciplinary divides.


1. Trends in world population

2. Exponential growth

3. Immigration and population growth

Related Nova topics:

Australia’s threatened species

Cleaner production – a solution to pollution?

Feeding the future – sustainable agriculture

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