Even if Korean reunification happens now, a declining population both in the South and the North is expected to lead to an overall drop in the population starting in 2034.
There have been expectations that North Korea's young population could solve South Korea's low birthrate following reunification. But the latest study by Choi Joon-wook at the Korea Institute of Public Finance pours cold water on such hopes.
The main reason for the population decline is that North Korea is already suffering from a low birthrate and aging population. As of 2015, North Korea's birthrate stood at 1.94 children by the UN tally. That is far less than the average birthrate of 4.75 in other underdeveloped countries.
"Countries with low per-capita GDP usually have high birthrates, but North Korea is unique by not being part of that trend," the study says.
The development is mainly due to the absurdly extended conscription of young North Korean men, which delays the marrying age, and a large number of North Korean women who work. The birthrate in the North declined much sooner than its economic level would suggest.
The report said South Korea and China saw rising populations in phases of high growth, which resulted in economic expansion. But that is unlikely to happen in North Korea.
The World Health Organization said the average life expectancy in North Korea as of 2015 was 70.6, which is also high compared to the country's income level and not far short of the global average of 71.4. North Korea has already had an aging population where people over 65 account for more than seven percent of the population since 2001. By 2027, elderly people are expected to account for more than 14 percent and by 2038 for more than 20 percent, or a super-aged society. That is less than 10 years later than South Korea.
If the two Koreas reunify, there is a high chance that the aging problem will grow worse. The former East Germany's birthrate was 1.5 children in 1989, prior to unification. By 1993, it had halved to 0.7.
Germany's birthrate increased afterward but still hovers below pre-unification levels. Other former communist countries saw similar trends.
On the other hand, advanced medical care in South Korea is going to ensure that people live longer and longer.
If the two Koreans were to reunify now, North Korea's population of an estimated 25.01 million is expected to rise to 26.39 million by 2036. But the South Korean population is expected to decline starting in 2032, and the combined population will peak in 2033 at 79.25 million. It is expected to shrink steadily to 69.67 million in 2061.
"There is actually a higher possibility that we will be saddled with an increased welfare burden to care for the elderly after reunification," Choi said.
North Koreans dance in a square in Pyongyang to celebrate the launch of a Hwasong-15 intercontinental ballistic missile, in this photo released by the [North] Korean Central News Agency on Nov. 30. /Yonhap