Aging Societies

Dynamics of Population Aging

Indicators of aging—such as the proportion of a population that is age 60 or over, or age 80 or over, and a population's median age—are commonly used to evaluate the population aging process.

By 2010, the population age 60 or over accounted for 11% of the world population, 3 percentage points higher than in the middle of the 20th century. This proportion is projected to double by 2050, a level that has already been achieved in the more developed regions (as classified by the United Nations). Such a high figure stands in stark contrast to the 5% level found among the least developed countries and 9% in the other less developed countries. As much as 33% of the population will be at least 60 years old in the more developed regions by 2050. The proportion age 60 or older in the less developed regions had not grown much since 1950 until entering the 21st century, and it is projected to more than double in next 40 years (United Nations, 2008).

As the more developed regions continue to age, the pace of aging has quickened. A single percentage point increase in the proportion of the population age 80 or over, otherwise known as the “oldest old,” from 1% to 2%, took 30 years to accomplish, between 1950 and 1980. Subsequently, it took only 15 years to surpass 3% in 1995 and another 15 years to reach 4.3% in 2010. It is now projected to take only 10 years to increase an additional percentage point for each decade until 2030, after which the time required to increase 1 percentage point will decline to only 5 years (Figure 1).

The eight most populous countries have distinct aging patterns. Japan saw its population age dramatically in the 20th century and will continue to see an aging trend, albeit at a reduced speed. The U.S. population rapidly grew older in the latter half of the 20th century, but that speed was tempered as it approached the 21st century. The pace of aging has increased in recent years but will likely decrease once again as we approach midcentury. Some countries, such as China, Brazil, [Page 35]Indonesia, and India, were quite “young” in the 20th century but have now begun to age much faster. Pakistan's population had been getting considerably younger in the 20th century, but the proportion age 60 or older has been rising and will eventually attain and then surpass the level witnessed in 1950. Nigeria is also expected to experience population aging in the next couple of decades.

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