World Population Won’t Stabilize This Century After All

By Ben Thomas | September 18, 2014 1:02 pm


It’s no secret that the world’s population is growing. The 7.2 billion humans currently on Earth may represent only a fraction of what’s to come. And although previous studies have predicted that the world’s population will stabilize around 2050, a new study projects that the population may continue to grow, to the end of this century and beyond: to 9.6 billion in 2050 and 10.9 billion in 2100.

The Problem of Projections

One of the landmark studies on population projections came in 2001, in which researchers projected that the world’s population would stop growing before the century was out. In 2012, a report from the United Nations tempered that projection, pointing to a stabilization point sometime after the year 2100. But these UN projections have drawn criticism from other population researchers, mainly because they’re a little clunky. For example, the UN gets its “high” and “low” predictions by adding or subtracting half a child from the mean fertility rate it projects — not exactly a precise formula for predicting the probability of population growth in individual areas.

And according to Patrick Gerland, a senior analyst at the UN’s Department of Economic and Social Affairs, there’s an even more significant problem with these projections: They depend on the false assumption that fertility rates in Sub-Saharan Africa will decline as the continent’s growing population gets more and more densely packed together.

This UN assumption is based on data from the 1970s population booms in Asia and South America, where fertility rates grew rapidly, then began to decline, then stabilized around an average of 1.5 to 2 children per woman. But while that may have been what happened in the past, Gerland says, it’s not an accurate representation of what’s happening with the Sub-Saharan population right now.

Assessing Africa

Although it’s true that fertility has been declining in Africa over the past ten years, it’s only declining at one quarter the rate it did in Asia and South America in the ’70s. That means the African population is likely to continue to grow much more rapidly than populations in other areas of the world — a fact, Gerland says, that the UN predictions don’t account for.

There are three reasons for Sub-Saharan Africa’s lower-than-expected rate of fertility decline: First, studies have found that social norms throughout the Sub-Saharan region idealize the average family as having 4.5 children — higher than family-size ideals in other parts of the world. Second, the supply of contraception in the Sub-Sahara has remained far below the demand for years. And third, improving medical conditions mean the spread of HIV has been slowed throughout the African continent.

Gerland and his research team used all these facts to construct a new mathematical model. The newer forecast uses Basyesian statistical methods — a first for the UN reports — to combine government data and expert forecasts for such things as mortality rates, fertility rates and international migration. According to this model’s results, there’s an 80 percent chance that the world population will increase from its current 7.2 billion to somewhere between 9.6 and 12.3 billion by the year 2100. The results are published this week in the journal Science.


Left, world population projected to 2100. Dotted lines are the range of error using the older scenario method, while shaded regions are the uncertainties using statistical methods. Darker shading=80 percent confidence; lighter shading=95 percent confidence. At right, the population projections for each continent. Credit: A. Raftery / Univ. of Washington

Hope for Help

These new projections bring some obvious concerns. The environmental impact of a growing Sub-Saharan population could be problematic — not only for the continent itself, but for other world regions such as China, which provides increasing amounts of infrastructure and other material resources to developing Sub-Saharan nations.

Although Gerland’s projection may sound sobering, the fact that it’s arrived so early in this century may mean there’s still time to stabilize the situation. The researchers suggest upping investment in Sub-Saharan girls’ education and in reliable contraception, which could help stabilize the region’s family sizes around a more typical international standard of 1.5 to 2 children per woman.

If an intervention like this can succeed, Sub-Saharan countries with high fertility rates may be able to achieve modern population sizes quickly without putting too much strain on the environment — and in a world where people on all continents contribute to the global economy, that could benefit growing populations everywhere.


Image by tai11 / Shutterstock

CATEGORIZED UNDER: Living World, top posts
MORE ABOUT: demographics
  • Enopoletus Harding

    This depends on plenty of variables: agricultural productivity, urbanization, consequences for male impregnation of multiple partners, cost of raising children, percentage of the labor force working full-time for an employer- it all matters.

  • Uncle Al

    Value was stolen from the productive then fed to the reproductive without limit, carte blanche. Did somebody bobble a sign in the prognosticative spreadsheeet?

    Go ahead, censor this post, too. Don’t change the course, rotate the compass.

    • lololololcaster

      What is with old white conservative men. Are you all mental ? Is there something in the water ?

      • Buddy199

        What is it with angry looney lefties?

        • colowww

          The looney conservatives have been fighting getting these people better access to contraception for decades.

        • lololololcaster

          Kettle meet pot.

  • Sally Bell

    We all want to improve health via medicine, hygiene, etc. But the unintended consequence has been overpopulation, leading to greater poverty, malnutrition, environmental degradation, etc. in many places. Personally, I believe birth control is as important as disease control, and education and action on that should be part of nearly all health efforts in overpopulated areas.

  • sam101200

    The ICC should idict the Pope for crimes against humanity.

    • Mark Miller

      A nurse once said to me (her self a Catholic mother of only 2) that she didn’t see what all this fuss about population was all about because inevitably a really nasty virus would come along and wipe out billions and we’ll be glad for all the people we have. In that case, the Pope should get a medal.

      • lololololcaster

        Wow a nurse ! Amazing. What else did this well of wisdom say ? Pray tell us so we may plan our future social policies based on her ideas.

        • Mark Miller

          Oh common chill out, it was an interesting observation and I’m sure she used birth control. And what makes you think we can plan anything?

          • lololololcaster

            Yeah, its a joke, lets yak it out. I don’t mind that at all.

            But then again these are the same dirt eaters who believe the earth is 6000 years old.

            At this point f*** laughing, I am ready to cry for humanity.

          • lololololcaster

            And let me point out to you, this isn’t a left or right politic issue. I have seen numbskull lefties who are anti-vaccine just as much as numbskull righties. Different beliefs, same anti-darwinian outcome.

            I wish we had IQ tests to prevent breeding these cattle.

          • lololololcaster

            Did you read about the Republican soon to be senator from the South who was talking about engaging in a little ‘laser war” against Mexico ? Wanted to send ‘them jets’ for a bit to teach them a lesson :(

            Forget chilling out, I am looking for the nearest exit off this idiotic planet.

          • Mark Miller

            Perhaps your lizard brain just overreacts.

    • Buddy199

      And the Hasidic Jews, and the Mormons, and the Amish, and of course all those dirty Mexicans and Guatemalans and Africans and…

    • M J

      If you think the existence of people is a problem, you might want to rethink what you value about your life! How lucky YOU are to have one… and you know what… more people means ecomonic boosts !!! The more people to buy, the more the companies will spend to supply…. Didn’t you hear in 2010, companies have money to spend, they just are not confident in the purchasing power of the demographics… why? Because too few 48 year olds… why? Because most people are rationale and save for the future, but families, they need to spend on the account of growing people .. i.e. education, new clothes, school supplies… and 48 is the age where the average parent has an 18 year old……. only if you knew !

      • Steve Potkanski

        you are a speck in a tick of time – dont get all uppity

      • rrocklin

        Less resources, more crowds, more environmental degredation, more poverty and malnutrition, decreased quality of life.

  • colowww

    Population growth has slowed down way too little, way too late. The world is already vastly overpopulated with 7 billion people. Three billion already live in extreme poverty and most of the future billions will fall into that category. Sure growth has slowed down substantially, but it is still growing very fast from a historic perspective. Its like an over loaded dump truck speeding through a school zone at 120 miles per hour, then slowing down to 80 MPH. “See its not speeding any more.”

    • Daniel LaLiberte

      Do you believe people living in poverty are having more babies and that is causing the population to grow? In fact everyone is having fewer babies, and fertility is declining, just not as fast as the decline in infant mortality. So education and empowerment of women is needed to reduce fertility even faster.

      But even after we all reach 2 children per family, population can grow because there are not as many older people dying to be replaced in equal numbers by new babies. It can take a couple generations for population to stabilize.

  • colowww

    400% more people in Africa = 400% fewer elephants, rhinos, lions, leopards, giraffes, hippos, and so on….. Of course many will go extinct all together.

  • M J

    Stop making the existence of people a bad thing!!!!!!!!!!!!!! “We love life, our life !! “” …..

  • madisontruth

    non-sustainable, thanks to human entitlement.

  • Brett Champion

    We have absolutely no idea what the world’s population will be in 2050, let alone 2100.

  • Brian Allan

    ebola or something similar will eventually reduce our numbers or we’ll simply all starve to death. It is the natural order, like it or not!

  • VideoGuy

    We all should be paying attention to “Demographics”.
    The U.S. Census Bureau has determined that the golden number for fertility is 2.1. Rates above for two generations and the population will grow. Below and the population will not. Current rates:
    America – 2.0
    Russia – 1.61
    China – 1.55
    Italy – 1.41
    Germany – 1.42
    Greece – 1.40
    Japan – 1.39
    More Japanese consumers are buying adult diapers the buying baby diapers. In 2013 a Japanese foreign minister urged the elderly to “Hurry up and die”. For every 10 births in Russia there are 13 abortions. America has more dogs that people. Pets outnumber children in America 4 to 1. As less people are born to replace those that die means less people to fill jobs. More taxes to support the programs that take care of the elderly. Think Social Security problems! Welfare, etc. Think you have high healthcare costs now? Wait! With fewer people in the workforce, technological and competitive advantages go into the tank. Fewer workers producing goods and providing taxes. There are many good things about a lower birth rate but beware of unintended consequences. Wars, abortions, ubiquitous contraception all have consequences. Just saying!

  • Fabrizio Brader

    The number of the world population isn’t a problem itself, the real problem is that it doesn’t exist a rational sharing of food, wealth and vital spaces. Too much food thrown, too much poverty and too much demographic concentration around the big cities. If we watch a 10 millions crowd from a satellite this becomes absolutely invisible if compared to the landscape which surrounds it.

  • Puzzleduck

    “The 7.2 billion humans currently on Earth may represent only a fraction of what’s to come.”
    There’s no “may” about it.


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