London (CNN) Ahead of this weekend's G20 summit in Japan, an elderly idol group called Obachaaan released a music video welcoming the new visitors to their city, Osaka.

The energetic seniors dance and rap through the port city in the slapstick rap-style video, called "Oba Funk Osaka" -- which charmed at least one world leader.

"Like Japan, Singapore too has an aging population," Singaporean Prime Minister Lee Hsien Loong wrote in a Facebook post in reference to the demographic issue being on the global agenda at the G20 for the first time this year.

"Staying active and engaged with current affairs is certainly one lesson we can learn from these obachans (grandmothers)."

Policy-makers, like Lee, are puzzling over how to deal with world's aging population . The over-60s are growing faster than all younger age groups, thanks to people living longer, healthier lives and declining birth rates in many countries.

It's an issue that is feared to have a swathe of socio-economic consequences -- such as lower economic growth , high public debt burdens, intergenerational tensions, higher health care or pension costs.

And if you delve into the regional data, it is Europe that is leading the demographic change.

According to United Nations population data , the continent is home to the oldest populations in the world where one in four of all Europeans are aged 60 and over.

The European Union's birth rate is at 1.6 , far below the average 2.1 births per women needed for a population to sustain itself from one generation to the next.

A gendered issue

According to Umberto Cattaneo, an economist at the International Labor Organization (ILO), the rise in short-term employment contracts, the gender pay gap and lack of affordable childcare are some of the reasons why couples are opting against having children in Europe.

And the situation poses a Catch-22 for women, with the burden of elderly care potentially falling on them if policy-makers fail to provide long-term programs for the elderly.

"In Europe and Central Asia women perform 67% of the total care in unpaid care work in the region," Cattaneo said. "The risk is that if there is not enough investment in this sector basically women will take up the additional unpaid care work."

The aging population feeds into a broader trend in Europe, the only region in the world whose population is falling.

In the next 30 years, the United Nations projects t he global population will reach nearly 10 billion people; in Europe though it will fall by as much as 26 million by 2050.

According to UN projections, between 2015 and 2017 countries in eastern Europe saw the biggest decreases in population -- with Bulgaria, Latvia, Ukraine, Poland and Hungary falling the most.

"I would say it's dire in eastern Europe," said Brienna Perelli-Harris, a lecturer in demography at the University of Southampton, adding that the trend began after the collapse of socialism in eastern Europe -- with fertility rates declining to 1.3 or lower.

"Eastern European countries have the added burden of emigration," where people are moving to richer European nations for work, she said.

But financial incentives and public awareness campaigns can come across as overbearing. A Polish government public awareness campaign, which called on couples to "breed like rabbits," was widely criticized in Poland, according to AFP.

While a 2007 policy in Russia, which gave maternity capital of up to $10,000 for mortgages for mothers with a second child resulted in black market trading of the capital. "Many of the couples just wanted the cash," Perelli Harris said.

Immigration has been cited as a way to plug the elderly care gap and even out population decline, but it has turned into too toxic an issue for governments to advocate for in recent years.

"Germany allowed refugees in partially because there is awareness they needed more workers and higher labor force," Perelli Harris said, but the issue has faced backlash from more nativist elements in Europe.

The far-right Alternative for Germany, or AfD, made ethno-nationalistic appeals in a 2017 election poster that showed a pregnant white woman with a caption, "New Germans? We'll make them ourselves." It was a campaign that was criticized for echoing Germany's Nazi past.

But aging should not be cause for pessimism, said Lars Sondergaard, the World Bank's program leader for education, health social protection and jobs for EU member states.

It is instead an "opportunity," he said. "At the heart, you've got to make individuals more productive to offset aging," he said.

The ILO estimates that doubling investments into the care economy by European and Central Asian countries would be lucrative. "It would result in 83 million jobs, with 70 million in care sector and 30 million indirect jobs by 2030," ILO economist Cattaneo said. "But they need to start investing now."

Sondergaard said a holistic approach is needed for an individual country's needs. Solutions could include keeping the older population in the labor force with greater skills training, ensuring pension inequality does not crop up and raising the retirement age.

All of which could prove -- as the Osaka-based Obachaaan dancing group already knows -- that life certainly does not stop at 60.