'Demographic dividend'

Population growth continues to gain momentum in the world's developing countries, according to new figures from the United Nations Population Fund (UNFPA). But Michael Herrmann, the UNFPA's adviser on population and economic development, points out that there are more and more young people in the world's poorest countries.

Herrmann said that these societies could end up benefiting from a "demographic dividend," where the working age population is larger than the dependent population. According to figures from the State of the World Population 2014 report, released Tuesday, there are currently around 1.8 billion people in the world aged between 10 and 24 years.

"We often hear that young people represent the future," said Hermann. "Now we must invest in this future."

In the world's poorest countries, the proportion of young people is growing especially fast. Currently, the world's youth represent over a quarter of the total global population; in Chad or Sudan, however, that share is as high as a third. This means, according to UNFPA, that there will soon be many more people able to productively contribute to their society's prosperity.

In sub-Saharan Africa, there are expected to be twice as many people between the ages of 15 and 24 by mid-century. The dividend results when these people are well-educated, and resources are not depleted by higher numbers of offspring.

"We need to look at the development of human capital in its entirety," said Herrmann, adding that it's not just a matter of focusing on education and professional qualifications.

He pointed out that it was important to also take into account health and sexual education, early on.

Explosive population growth

The world is facing enormous challenges, according to Renate Bähr, executive director of the German Foundation for World Population, an NGO that works closely with the UN. "Too little is being done," she said, referring to the funds needed for education.

"In some regions, the number of students has grown by a third between 2000 and 2010. That means that funding must be increased by 30 percent, in order to meet the minimum standard." But the international development budgets have not been able to keep pace with demand.

Bähr believes it's particularly important to strengthen the role of women and girls. "In areas where equality between the sexes is high, we see a corresponding decline in birth rates," she said. Bähr reiterated that, according to UNFPA's report, one third of girls in the world's poorest countries are still forcibly married - "39,000 young girls every day."

If the necessary investments are not carried out, UNFPA foresees a bleak future. "All our projections, even the negative ones, assume that the birth rates will decline," said Herrmann. According to UNFPA's forecast, the global population will reach 9 billion by 2050, increasing to 10 billion by the end of the century.

"Now, if every second woman has one child more than our estimates, the world's population will increase to 17 billion by 2100," said Herrmann. He said that the right policies today will mean a "huge difference" in the future.

Germany: the other end of the spectrum

Bucking the global trend, the situation in Europe and Germany is marked by a steadily aging population. People in Germany live, on average, to a ripe old age: 78 in men, and 83 in women, compared to the global average of 68 and 72 years, respectively.

But the proportion of young people in Germany between the ages of 10 and 24 is only 15 percent, much lower than the global average of 25 percent, and even 2 percent lower than the average of other industrialized countries.

According to UNFPA's calculations, the German population will shrink by 0.1 percent from 2010 to 2015. However, the situation is even worse in many Eastern European nations characterized by negative population growth, such as Russia (-0.2 percent), Serbia (-0.5 percent), Latvia (-0.6 percent) and Moldova (-0.8 percent). Overall, the UNFPA's report highlights 18 countries with a shrinking population.