13 March 2007
NEW YORK, 13 March (United Nations Population Division) -- The world population continues its path towards population ageing and is on track to surpass 9 billion persons by 2050, as revealed by the newly released 2006 Revision of the official United Nations population estimates and projections.

The results of the 2006 Revision -- which provide the population basis for the assessment of trends at the global, regional and national levels, and serve as input for calculating many key indicators in the United Nations system -- incorporate the findings of the most recent national population censuses and of the numerous specialized population surveys carried out around the world.

According to the 2006 Revision, the world population will likely increase by 2.5 billion over the next 43 years, passing from the current 6.7 billion to 9.2 billion in 2050. This increase is equivalent to the total size of the world population in 1950, and it will be absorbed mostly by the less developed regions, whose population is projected to rise from 5.4 billion in 2007 to 7.9 billion in 2050. In contrast, the population of the more developed regions is expected to remain largely unchanged at 1.2 billion, and would have declined, were it not for the projected net migration from developing to developed countries, which is expected to average 2.3 million persons annually.

As a result of declining fertility and increasing longevity, the populations of more and more countries are ageing rapidly. Between 2005 and 2050, half of the increase in the world population will be accounted for by a rise in the population aged 60 years or over, whereas the number of children (persons under age 15) will decline slightly. Furthermore, in the more developed regions, the population aged 60 or over is expected to nearly double (from 245 million in 2005 to 406 million in 2050), whereas that of persons under age 60 will likely decline (from 971 million in 2005 to 839 million in 2050).

Realization of these projections is contingent on ensuring that fertility continues to decline in developing countries. According to the 2006 Revision, fertility in the less developed countries as a whole is expected to drop from 2.75 children per woman in 2005-2010 to 2.05 in 2045-2050. The reduction expected in the group of 50 least developed countries is even sharper: from 4.63 children per woman to 2.50 children per woman. To achieve such reductions, it is essential that access to family planning expands in the poorest countries. The urgency of realizing the reductions of fertility projected is brought into focus by considering that, if fertility were to remain constant at the levels estimated for 2000-2005, the population of the less developed regions would increase to 10.6 billion instead of the 7.9 billion projected by assuming that fertility declines. That is, without further reductions of fertility, the world population could increase by twice as many people as those alive in 1950.

The projected population trends also depend on achieving a major increase in the proportion of AIDS patients who get antiretroviral therapy to treat the disease, and on the success of efforts to control the further spread of HIV. In the 2006 Revision, 62 countries are considered to be highly affected by the HIV/AIDS epidemic, 40 of which are located in Africa. In projecting the effect of the disease, it is assumed that 31 of the most affected countries will manage to provide, by 2015, antiretroviral treatment to 70 per cent or more of the persons suffering from AIDS. In the rest of the affected countries, treatment levels are expected to be lower, reaching between 40 and 50 per cent by 2015. It is further assumed that persons receiving treatment survive, on average, 17.5 years instead of the 10 years expected in the absence of treatment. Mainly as a result of these assumptions, and owing to the downward revision of the prevalence of HIV/AIDS in countries where nationally representative data on the epidemic have become available, an estimated 32 million fewer deaths are projected to occur during 2005-2020 in the 62 most affected countries according to the 2006 Revision than would have occurred if death rates were the same as in the 2004 Revision. These changes also contribute to make the population projected to 2050 in the 2006 Revision larger than that in the 2004 Revision (9.2 billion vs. 9.1 billion).