Why you should care
Because the world’s major demographic issue is not what you thought it was.
For decades we’ve read scary headlines about the consequences of overpopulation, from food shortages and wars to running out of water. But it turns out that the world’s population growth rate is now half of what it was forty years ago: 1.2 percent. After peaking at 2.1 in the 1970s, it hit the brakes – and at this pace the number of people on Earth should stop growing and start falling in less than 50 years.
Today the planet is home to 7.2 billion people — more than at any point in recorded history. Yet one hundred years from now, the number will be smaller. Back in 1950, the global fertility rate averaged about five children per woman, but today that global average is down to 2.58 (total fertility rate as of 2011).
- Fertility rate — Average number of children born per woman if she lived through her childbearing years
- Birth rate — Total average annual births per 1000 people
- Replacement rate — Average number of children born to each woman to maintain current population levels. In most industrialized countries it is 2.1: lower than that, population contracts, higher than that, it grows.
Of course, the drop in fertility varies from country to country and continent to continent. Asia, the world’s most crowded continent at 4.3 billion, had a fertility rate of 5.8 in 1960, but by 2014 it’s expected to fall to 2.1 percent. This represents a major milestone, since 2.1 percent is considered the magic “replacement rate” that, if sustained, creates long-term population equilibrium.
India, long-associated with high population growth, charted a fertility rate of 2.5 percent as of 2011, only a few ticks above the U.S. that year. In his analysis of the potential causes for India’s fertility decline, Stanford lecturer Martin W. Lewis notes that of all the possible correlations (women’s education, urbanization, spread of electricity), the one that matches fertility decline most closely is television ownership. Television, he theorizes, offers a model of families successfully transitioning into modernity — usually with few children to support.
By 2050 developed countries will have twice as many old people as young ones.
Fertility rates remain high across Africa, which is home to 29 of the 31 “high fertility” countries where the average women has 5 or more children. Niger ranks at the top with an average of 7 children per woman. Still, these “high fertility” regions account for just 9 percent of the world’s population: 48 percent live in “low fertility” countries (< 2.1 children), and another 43 percent live in “intermediate fertility” countries (between 2.1 and 5 children).
So is overpopulation a myth? Yes and no. Fertility rates continue to fall, yet the U.N. still predicts that the world will balloon to 10 billion inhabitants by the end of the century. That’s because the fall in fertility rates takes a long time to show up as a subsequent fall in birth rates. “Demographic momentum” wears on because there’s still a generation of people born in the previous echo baby boom who are just entering their reproductive years.
Which brings us to the issue of generational differences. As fertility falls, countries initially benefit from having a bulk of working-aged adults and relatively fewer dependent children and old people — known as a “demographic dividend.” Eventually that benefit reverses: By 2050 developed countries will have twice as many old people as young ones. As you see this situation spread across the map, you begin to understand the looming problem each country will have to manage on its own terms. It’s a difficult trend to reverse once it’s in motion, as Japan well knows after decades of unsuccessful state campaigns promoting having children.
So it turns out we do have a major population problem – it just may not be the one we thought.
Rebecca Moreno contributed to this report.