Population explosion

The United Nations on Thursday (13.06.2013) released revisions to its "World Population Prospects" report, which now predicts the world population will reach 9.6 billion by 2050. The UN's John Wilmoth talked to DW about the causes and consequences of increasing population growth.

DW: What factors or new information accounted for the revision? What are its most significant findings?

John Wilmoth: We only change things based on new information as it becomes available. In several of the least developed countries, many of them in sub-Saharan Africa, we found fertility levels higher than what we had expected. In fact, they've probably been higher than we thought in the last decade or so - the evidence for this sort of thing accumulates over time.

The impact of changing our current fertility estimates for many of these fast-growing countries is that we project the world population will be larger than what we had expected. By 2050, the middle-of-the-road scenario has increased from 9.3 to 9.6 billion. And in 2100, our medium variant projection has gone up from 10.1 to 10.9 billion. But I would emphasize that there's a lot of uncertainty about population projections.

The population is growing in poorer countries that consume fewer resources, and shrinking in wealthier countries where more resources are consumed. How could this affect the human footprint, and issues like climate change?

The ecological footprint in developed countries isn't going to shrink, unless they change their habits. Developing countries will also grow economically, and as a result their consumption of fossil fuels and other resources is increasing - also in large part as a result of changes in their consumption patterns. We can expect that will continue.

Africa's population is expected to more than double. What does it mean for the future of the continent, for example on issues like food security? What impacts could it have on development there?

Rapid population growth presents a challenge for development for several reasons. One is making available the necessary food, water, and other resources necessary for the population to live at an adequate standard of living, or in fact to improve it. The challenge is expanding the economic resources to support the population.

Another challenge beyond this numbers game is the age distribution, because populations that are growing rapidly have a high proportion of youth, who need to be educated, and eventually enter the labor market and find decent work. These are really important social challenges, as a "youth bulge" goes with rapid population development.

If fertility then falls, this can be a very beneficial time for countries - often referred to as the "demographic dividend" - because you have a high ration of workers. Many developing countries, China and India in particular, have begun to enjoy this dividend. If other developing countries can successfully reduce their fertility levels over the coming years, then they too could experience this benefit.

According to the report, some of the poorest countries are growing at the highest rates. What are the reasons for that, and what can be done to check such population growth?

The experience of many African countries in the 1990s seems to suggest that fertility was beginning to fall there, as it did in East Asia earlier. That was attributed to various factors, like changes in valuing education. This basically means people delay their entry into child bearing and parenting, which also prepares them for the work world where combining children and work is not so easy. Especially as women enter the workforce, the incentives shift even farther toward having smaller families.

At the same time, there was a cultural change about the value of small families, there was also a substantial effort to make modern contraception more available to people. So, you combine the changing economic incentives, which really go back to education and market-based economies, with the cultural changes and access to contraception, and that seemed to be leading to a reduction in fertility.

More recently, that seems to have slowed down, and more research is needed to find out why this has happened. Some people have argued that it's due to the reduction over the last two decades in the effort to broaden access to family planning. The "Family Planning 2020" initiative is one response to this.

Countries like Germany exhibit an inverted population pyramid structure, and soon countries like China will too. What problems are associated with this?

There are known and unknown problems. Known problems include social and financial arrangements for the elderly: as the older population grows, it becomes increasingly expensive to support it through health care and pensions. This is a major challenge. It's not just a question of how many older people there are; it's also a question of how much money is spent to support them. We know that one way to control this is for example to gradually shift the retirement age higher.

But one problem we haven't talked a lot about with countries that have a below-replacement level of about 2.1 children per woman - this inverted pyramid you mentioned - is this built environment we have. We've seen this a little bit in some cities that have become depopulated - the challenges of dealing with the built environment. How do you decommission buildings, how do you convert industrial areas back to green spaces, for example? The challenges of dealing with population decline I think are not very well understood, because it's really just starting with countries like Germany and Japan.

People often ask me, what's the best population trend? I do believe it's prudent to avoid these extremes, and be somewhere in the middle.

John Wilmoth is director of the population division at the United Nations. He was previously a professor of demography at the University of California at Berkeley.