In February the United Nations Population Division released the 2004 revisions to its World Population Prospects publication, projecting how much further world population is likely to grow.
Under the UN’s medium variant scenario, world population will reach 9.1 billion in 2050. This represents a slight upward revision from more recent estimates that had world population reaching just 8.9 billion in 2050.
Almost all of that growth will occur in the developing world. Ninety-five percent of all population growth today is occurring in the developing world compared to just 5 percent in the developed world according to the UN Population Division. Of that estimated 9.1 billion, only slightly over 1.2 billion will live in countries that are currently designated as developed — about what the population of the developed world is today.
The medium variant assumes that the total fertility for women worldwide is going to drop from its current level of 2.6 to just slightly over 2 by 2050. If the worldwide TFR average were to only decline slightly to just over 2.5 — the high variant scenario — world population would reach 10.6 billion by 2050. If it were to decline faster, however, and fall to about 1.5 — the low variant — world population would reach just 7.6 billion in 2050.
Global life expectancy continues to rise. The Population Division reports that global life expectancy rose from an estimated 47 years in 1950-1955 to 65 years in 2000-2005. By 2045-50, global life expectancy is expected to rise to 75 years. In developed countries, where life expectancy averages 76 years today, it is expected to reach 82 years by 2045-50.
Those life expectancy projections assume that the developing world will be able to implement effective programs and policies to halt excess mortality due to HIV/AIDS. Whether or not this happens remains to be seen. As the Population Division reports, HIV/AIDS has taken a serious toll on life expectancy in some parts of Africa. In Southern Africa, for example, life expectancy fell from 62 years in 1990-1995 to just 48 years in 2000-2005, and is expected to drop even further to just 43 years over the next decade. The Population Division projects that 43 will represent a bottoming out of the crisis and that life expectancy in Southern Africa will then slowly begin to rise again.
One of the main effects of the worldwide decline in total fertility rates will be an aging of the population that is unprecedented in human history. According to the Population Division, the number of people over the age of 60 is expected to triple from an estimated 672 million in 2005 to a whopping 1.9 billion by 2050. There will also be a 4.5-fold increase in the number of people over the age of 80, from an estimated 86 million today to 394 million in 2050.
World Population Prospects: The 2004 Revision. (PDF) United Nations Population Division, February 2005.
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