When Lin Xu, an office worker, crams himself into sardine-can-like bus every morning, sometimes with his face pressing against a window, he cannot see what could possibly be wrong with China's one-child policy.

The family-planning policy was introduced in the 1970s to rein in China's surging population by encouraging late marriages and late childbearing and limiting most urban couples to one child and most rural couples to two children.

It's estimated that without the policy, the country's population would be 400 million more than the current 1.3 billion people, according to the National Population and Family Planning Commission.

But there is a price to pay. Recently, the graying workforce and its subsequent social problems have plunged Shanghai into encouraging eligible couples to have two children, a move triggering widespread speculation of a policy shift.

China's family-planning authority refused to make comments on the prospect of a policy shift, but some scholars are advocating changes, because threats are real.

Workforce shortage

Across China, each couple has 1.6 or 1.7 kids on average, a fertility rate kept for 17 years. The number of offspring for population maintenance is a 2.1, according to Wang Guangzhou, professor with the Chinese Academy of Social Sciences (CASS).

At this rate, the working population will dwindle by 10 million each year after 2025, and the number of young people between 20 and 24 will drop by one-fourth in the next decade, estimated Zeng Yi, a population economist with the Peking University.

"Young people of this age group are most energetic, productive and willing to learn," said Ji Baocheng, president of the Renmin University of China.

For the past two years, he has submitted a proposal to reconsider the family-planning policy to China's top legislature.

Opponents argued the loss of workforce would be complemented by artificial intelligence, according to an article on an online forum bbs.uc.sina.com.cn.

But that takes time. China is already experiencing a shortfall of skilled workers starting from its southern economic powerhouse, the pearl river delta, in 2004.

About one-third of the region's employers said they had difficulties in recruiting enough people, according to Cai Fang, director of the Institute of Population and Labor Economics under CASS.

Some experts attribute the shortfall to fewer skilled workers available in the market. As the country enlarged its college enrollment scale since the 1990s and its people became more affluent, more parents choose to send their children to colleges -- instead of vocational schools -- for a better job prospect and better pay.

Graduates from vocational schools in China are popular with employers in recent years as they have practical skills and most often demand less pay than people with a college degree.

Cai, however, said "The population entering the workforce falls short of demand since 2004, and this gap is yawning if the current fertility rate remains unchanged."

While people still count on the surplus labor in the country's vast countryside, a report on China's population and labor issues published by the Social Sciences Academic Press said three-fourths of villages were running out of surplus labor.

Some scholars are concerned that the increasing labor costs in China might reduce its competitive edge. Peking University professor Zeng Yi feared China might fall behind India based on the projection the Indian workforce would double that of China in 20 years.

But Lin Xu doesn't care. Lin, a single-child at 25, interpreted the shrinking workforce as "less competition, hence more job opportunities and higher income."

"Chinese are used to dividing everything by 1.3 billion, and feel the pinch of everything 'per capita'," said Wang Guangzhou.

Perhaps rightly so. China feeds the world's 22 percent of people with 8 percent of world's arable land. Per capita resource of drinking water represents one-fourth of world's average, forestry one-eighth.