Dr Luke Buckmaster, Social Policy Section and Joanne Simon-Davies, Statistics and Mapping Section

How ‘big’ is Australia’s population likely to become by 2050?

Recently, the question of whether Australia’s future population should be ‘big’, ‘small’ or ‘sustainable’ has emerged as a political issue. Discussion of this issue has been stimulated, in part, by projections that Australia’s population may reach 35.9 million by 2050.

However, there has been some confusion in public debates about the precise status of these projections—are they based on formal population targets? How are population projections calculated? Is a population of 35.9 million by 2050 inevitable?

Current policy

Australia does not have a formal population policy that commits the country to a particular population target.

In April 2010, the Government established the new office of Minister for Population (later renamed Sustainable Population). The Minister’s main role will be to develop a sustainable population strategy through consideration of the likely size of Australia’s future population and the expected impact on areas such as transport, housing, infrastructure, employment and the environment.

The Minister is to be advised by three panels addressing the areas of demographic change and liveability, productivity and prosperity and sustainable development. The three panels have responsibility for providing advice that will form the basis of a public issues paper to be released in late 2010.

Population projections

Population projections produced by the Australian Bureau of Statistics (ABS) are not predictions or forecasts. Rather they illustrate growth and change in the population based on assumptions about future demographic trends. Broadly, these projections use assumptions about rates of fertility, mortality and net migration (incorporating current trends) and, by using different combinations of these assumptions, make estimates about the population into the future (currently to 2101).

ABS projections are presented in three series: A, B and C. Series B largely reflects current demographic trends, while Series A and C are based on high and low assumptions for each of the key demographic variables respectively.

The further the projections move into the future, the more speculative the assumptions they are based on. There is no certainty that the population projections will or will not be reached. One reason for this is that the assumptions cannot include unexpected events, social changes or government policy changes.

The ABS population projections are based on estimated resident population (ERP). The ERP is calculated by adding natural increase (the excess of births over deaths) and net overseas migration occurring during the period to the population at the beginning of the period.

The next ABS population projections will be released after the 2011 Census of Population and Housing and are not expected until 2013.

Australia’s projected population

As noted, recent debates about Australia’s population have centred on the projection that Australia’s population may reach 35.9 million by 2050. This figure comes from Treasury’s 2010 Intergenerational Report (IGR) (Australia to 2050: future challenges).

Under this projection, the population will continue to grow but annual rates of population growth would slow gradually. According to Treasury, the rate of increase will slow from 2.1 per cent in 2008–09 to 0.9 per cent in 2049–50.

The Treasury projection is also more or less consistent with the figure predicted by the ABS (35.5 million by 2056) in its middle range (Series B) projection for 2056. Whilst the ABS creates many alternative variations of the projections, Treasury used a combination of ABS and its own projections in the IGR.

According to the ABS, Australia’s estimated resident population at 30 June 2007 of 21.0 million people is projected to increase to between 30.9 and 42.5 million people by 2056; and to between 33.7 and 62.2 million people by 2101.

Interpreting the projections

As can be seen above, population projections vary widely depending on the assumptions used. The most widely used current figure, Treasury’s ‘35.9 million by 2050’ is a middle range projection largely reflecting current demographic trends. Nevertheless, even the ABS’s low growth (Series C) projection suggests that the population would reach 30 million by the middle of the century.

Population assumptions/projections can change markedly over even a relatively short period of time (for example, through changes in government policy). As a result, caution needs to be used when interpreting population projection data. For example, the 2004 ABS middle-range projection was for a population of 28.2 million by 2051—based on assumptions of a immigration rate of 110 000 and a fertility rate of 1.7. By 2008, the projection had increased to 35.5 million by 2056, with an immigration assumption of 180 000 and fertility rate of 1.8. This change reflected increases in the level of immigration and the birth rate over this time.

Therefore, a given population projection should not necessarily be taken as something ‘set in stone’. Rather, it should be seen as something that can change in a relatively short space of time in response to demographic changes (which themselves can be influenced by changes in the economy, public policy and the social environment).

Library publications and key documents

Australian Bureau of Statistics (ABS), Population Projections, Australia, 2006 to 2101, cat. no. 3222.0, ABS, Canberra, 4 September 2008, http://www.abs.gov.au/AUSSTATS/abs@.nsf/DetailsPage/3222.02006%20to%202101?OpenDocument

Treasury, Australia to 2050: future challenges, Intergenerational Report (IGR) Treasury, Canberra, 2010, http://www.treasury.gov.au/igr/igr2010/report/pdf/IGR_2010.pdf