Although the global population reached 8 billion in 2022, population growth continues to slow down. While the populations in some regions of the world are declining due to low fertility rates, more regions may go through the same experience in the near future according to projections.

The global population will reach its peak sometime in the second half of the 21st century, after which it will start declining. Unlike a half a century ago, the main driver of population growth is not births alone, but also the longer life expectancy. With the total fertility rate falling below the replacement level in many countries, global population growth will further slow down, and the proportion of children in the total population will gradually decline and that of people aged 65 or above will increase.

Among the sub-regions of the world, the decline in the fertility rate in East Asia is particularly high. As a matter of fact, East Asia completed its demographic transition within half a century to enter an era of low fertility and population decline. The population growth rate in East Asia dropped below 1 percent in 1993, while the fertility rate fell below the replacement level. The prolonged low fertility rate has led to negative population growth in China and a couple of other East Asian countries, with features of the second demographic transition becoming prominent.

The rate of natural change of population in Japan has been negative since 2005. In 2023, when the total population of East Asia was 1.66 billion, the total fertility rate was only 1.01 and the average life expectancy reached 78.9 years. Although projections vary in details, the trend of demographic changes is clear. A low fertility rate, population aging and negative population growth have become the "new normal" in East Asia.

The fertility rate in East Asia fell below the replacement level in the early 1990s; it has fallen further. The total fertility rate fell below 1 in South Korea in 2018. Japan has a slightly higher total fertility rate of about 1.21 in 2023. People's decision to get married later and couples' reluctance to have more children, or no children at all, are the main reasons behind the declining fertility rate.

Many countries, including Japan and South Korea, with low fertility rates have taken measures to encourage couples to have more children since the late 20th century. That the result of such policy interventions and other efforts to increase the fertility rate has often not been satisfactory imply there is no single and simplistic solution to the issue. Another strategy to respond to low fertility and population decline of some high-income countries is welcome immigrants.

Since the developed countries started experiencing population aging and stagnant population growth a few decades ago, they had much more time to formulate response policies and take measures to mitigate the negative effects of declining populations. However, most developing countries with low fertility rates and rapidly aging populations in the 21stcentury have to adapt to the rapid changes in a shorter period of time. As such, low or negative population growth and population aging will create bigger challenges for developing countries.

The change in China's population in the first two decades of 21stcentury reflects a clear trend. The reduction in the number of births and increasing longevity are the main reasons behind population aging. Although fluctuations in annual population indicators are somewhat influenced by unexpected events, China's population peaked in 2022, after which it has been declining, a phenomenon that is expected to continue.

Compared with a slower decline in the total population in the near future, the change in the population's age structure will be more significant, and the percentage of children in the total population could soon be less than that of the elderly people.

The continuous decline in the number of births in recent years can be attributed mainly to women marrying at a later age and postponing childbirth. And with the number of women of childbearing age declining, the number of births per year will continue to decline.

The introduction of childbearing support policies, including longer paid maternity leave could encourage more couples to have more than one child. Yet since the factors behind the negative population growth have been at play for decades, a short-term increase in the fertility rate will not have a significant impact on the trend of declining population.

If the fertility rate remains below a certain level for long, the change in the population's size and structure would largely depend on migration. The migration of people, mainly young and middle-aged people for work, will significantly change the size and age structure of the working-age population in their places of origin and destination, and its impact on the social and economic development of different regions will be different. At the same time, it will affect the marriage and childbirth decisions of the people. While declining children's population and increasing elderly population have become the new normal, population mobility can alter the population structure and impact socioeconomic development of different regions.

With better understanding of the population dynamics of East Asia, and learning from the experiences of countries with low fertility rates, we can make long-term plans and policies to respond to the potential challenges brought about by population changes in the 21st century.

The author is a professor at the Institute of Population and Labor Economics, Chinese Academy of Social Sciences. The views don't necessarily reflect those of China Daily.

The views don't necessarily reflect those of China Daily.

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