A severe labor shortage will damage the economic stability of the capital of Guangdong Province within the next two to three decades, authorities have said.

According to a report on the city's current and projected population structure, released last week by the Guangzhou municipal statistics bureau, by 2034, the size of the workforce will be less than half the total population.

The report said the city has been on a fast economic development track over the past two decades, as the population structure was in a "bonus period". This means the workforce was larger than the proportion of people who need to be supported, such as children and seniors.

The report defines children as people under 14 and seniors as those aged over 65.

The bulk of the current labor force was born in the baby boom of 1950 to 1965. Most of them will reach retirement age in about 20 years' time.

The report predicts the size of the workforce will stop growing in 2013.

By 2024, it will comprise fewer people than the number needing support.

By 2034, the total labor force, including migrant workers, will be less than 50 percent of the whole population of Guangzhou, the report said, meaning the bonus period, which started in 1983, will be replaced by a "debt period".

In a debt period, the size of the labor force continues to decrease and there are less job opportunities, leading to a general economic slowdown or recession.

Zheng Zizhen, director of the population research institute of the Guangdong Academy of Social Sciences, said: "Debt periods replacing bonus periods are an inevitable result of social development.

"The country's family planning policy has helped to postpone the end of the current bonus period."

One way to postpone the arrival of the debt period is to attract more migrant workers, Zheng said.

Switching from a labor-intensive economic model to a technology-intensive one is another, he said.