Downtown in central Seoul / gettyimagesbank

Korea's population is projected to continue on a downward spiral over the next 50 years, declining to 36.2 million by 2072 from the current 51.7 million, according to Statistics Korea's latest report released on Thursday.

The report by the state-run statistics agency suggests three different population projections, depending on the country's fertility rates in the near future. Under the most optimistic scenario of the three that posits maintaining a higher fertility rate than the current level, the Korean population is expected to log 42.82 million by 2072.

When calculated from an only slightly higher fertility rate than the current level of 0.7, as of the third quarter, the country's population in 2072 is forecast to fall to 36.2 million, while the projected number could reduce to as low as 30.1 million in the next five decades under the least optimistic scenario of the three possible trajectories.

With the generally gloomy projections, the country's year-on-year population is expected to fall by as much as 1.31 percent in 2072 from the 0.19 percent contraction in 2022.

By the age groups of the population composition, the proportion of economically productive population — those aged 15 to 64 — is expected to be lowered to 45.8 percent by 2072, a huge drop from 71.1 percent logged last year.

While the working-age population will be on a downward path, the proportion of the elderly population aged 65 or higher would increase to 47.7 percent by 2072, from 17.4 percent in 2022, outnumbering that of the productive population by then.

The elderly population aged 70 or higher is expected to increase from 5.92 million in 2022 to over 10 million in 2033, reaching over 14.7 million or 40.7 percent of the entire population projected in 2072.

In contrast, the proportion of the youth population aged 0 to 14 is projected to decrease to 6.6 percent from last year's 11.5 percent during the next fifty years. The youth population in 2072 would stand at approximately 2.38 million, which is only about 40 percent of the same demographic in 2022.

The statistics agency explained that the projections are the result of factoring in the 2022 population census as well as the recent trends of population change factors — such as births, deaths and increased immigration.

"Since the population estimates are calculated based on certain assumptions about future population changes, the actual population of the future could be different from the projections, depending on changes in the economic and social environment, government policies, or values of the society. The uncertainty of the estimation will increase as time passes," the report stated.

Meanwhile, another population projection made by the United Nations last year forecasts a population decline in 10 OECD countries — including Japan, Italy, Greece, Spain and Germany — during the 50 years from 2022 to 2072. Ten other countries — including the U.S., Canada, Australia, Sweden and Israel — are expected to continue increasing, while 16 countries — including Mexico, France and Colombia — are expected to fall after their periods of population increase for a while during the next 50 years.