The forecast by Park Myung-soo, a researcher at the Korea Employment Information Service, is based on assumptions that the country's falling birthrate and rapidly aging population will continue into the next decade.
"If the current trend of low births and aging population continues, the rate of workforce growth is likely to drop to 1 percent or lower from 2018 while economic expansion may post minus figures," the researcher said in his report that analyzes the correlation between workforce growth and economic growth.
"After the mid 2020s when the country enters into 'the 100 age era,' even the workforce growth may turn negative, further worsening minus growth of the economy," the researcher said, defining the era as the time the population's average age of death extends into their 90s.
Park also said in the report that the average age of the working population is likely to rise rapidly down the road amid falling birthrates.
The average working age reached 40.5 in 2000 before rising to 43.7 in 2010, the researcher said. The average is expected to go up to 46.3 in 2020 and 49.2 in 2030, respectively, he projected.
In order to prepare for the grim growth forecast, the country needs to encourage the economic participation of youth and women as well as the older population and foreign workers, he said.
South Korea's fertility rate remained at one of the lowest levels in the world with 1.2 children per woman in 2010.