China's population has more than doubled since 1950(1). In the 1950s and early 1960s the country's rapid population growth was fueled by Mao's pro-natalistic population policy. Since the introduction of a strict "one child" family planning program, China has brought its population growth under control. In the early 1990s China's Total Fertility Rate fell below the replacement level of about 2.1 children per woman. Currently, average fertility is far below replacement - possibly in the range of 1.3 to 1.5 children per women.(2) Most experts believe that by 2050 China's population will stabilize around 1.5 billion people and then begin to decline. However, the rapid fertility decline in the 1970s and 1980s will cause a very strong population aging in China after 2050.
With its 1.3 billion inhabitants, China is (or will be) a heavyweight in all global affairs - from global trade to environmental protection, from energy consumption to the international supply of labor. Whatever China's politicians decide in one of these sectors, it has implications for the whole world, because it immediately affects at least one fifth of the world's population.
Despite what critics may say, China has gained an enormous advantage by introducing the one-child family planning policy. With much smaller families parents and children of the post-fertility decline generation had unique advantages: The parents could invest more into the education and health of their children; women could concentrate more on their careers; and family income was shared among fewer family members, which increased living standards.(3) When the large generations from the 1950s and 1960s reached working age, China's economy as a whole benefited from an unprecedented demographic dividend. This large generation, together with massive rural-urban migration, fueled the urban labor markets with almost unlimited supply, which was essentially the basis of China becoming the global work-bench. The "golden years" of China in the 1990s were demographically defined by a large generation in working age, few children (thanks to the one-child policy) and still few older people due to previously high mortality. Essentially, China's population in the 1990-2010 period were young adults in prime working age - which was one of the main causes of the China's economic miracle.
China's greatest demographic risk is the unavoidable process of population aging, which will be one of the most drastic ever observed - both in terms of the speed and the absolute number of people affected. With the rapid decline of fertility within a few years from more than 6 children per women in the 1950s to less than 1.5 children per women in the 2010s the corresponding process of population aging, starting around 2030, will be equally rapid. When the "baby boom" generations from the 1950s and early 1960s begin to reach retirement after 2020 many people will face huge problems, because pension systems are absent or weak, and social security is lacking. Especially, the rural "baby boom" generation born under Mao will bear the burden of China's success. They had few children, worked hard all life, and will now face financial hardships or poverty in old age. Their only child (or very few children) will have moved away to some booming coastal city, while they will have to stay in the villages with little social and financial support. This abandoned (rural) generation will be the price of China's economic success.
Another demographic challenges in China is the extreme unequal sex ratio, which is now mainly caused by selective abortion carried out to ensure a male offspring under the pressure of the one-child family planning program. This is already causing a major marriage squeeze, which is amplified by women's increasing independence and growing expectations in their potential spouses (4, 5).