Superconvergence to Lower Global Fertility Rates

Nearly half the world’s population resides in the five most populous countries. China, India, The United States, Indonesia, and Brazil contain 3.518 billion people. And, as it happens, there is a superconvergnece to a lower fertility rate in each, albeit from different starting points sixty years ago.

Wealth, and advances in health, are the twin drivers of lower fertility rates because together they allow parents to invest a greater amount of resources in a fewer number of children. When adults become confident that risks of child mortality will sustainably decline, those forward looking expectations trigger different decisions about family formation.

Because population growth rates have impact on economic growth, interest rates, and natural resource consumption, the issue of population has for many decades been included in most discussions of planet-level limits. Imagine, for example, placing yourself in the above chart between 1965 and 1970—with no data about the future to come—and you can readily see why population fears were rampant during that era.

We are no longer living in 1967. If, in 2017, half the world’s population is converging towards a low fertility rate (and it’s more than half, when you include Russia, Japan, and the rest of the OECD) then you are not going to be able, through higher rates in other countries, to halt the decline on a global level. Indeed, if we calculate a population weighted average of the big five countries, we are already at a 2.03 fertility rate. Why? Because China, with the highest population and a crashing rate, pulls down the average of the top five, in the same way the top five pull down the average globally.

As you might have guessed, the final domain where population alarmists are making their stand is in Africa. According to the UN Population Revision 2017 (the source of the most recent data) Africa, collectively, has a fertility rate of 4.72 through 2015. But which way do you think it’s headed? True enough, the UN is currently projecting that fertility rates will head lower in Africa—but not quickly. Indeed, one of the most outlying projections the UN makes is for population growth in Nigeria, from 185.99 million currently to 410 million by mid-century, and finally to 793 million by the end of the century.

The UN’s population projection for Nigeria, a medium variant, seems highly improbable. One would have to assume that advances in health care, nutrition, wealth and the deployment of solar power and technology will completely pass over this West African nation. Moreover, when we look at a comparative size of Nigeria, overlaid on the US mid-Atlantic states, it would seem quite unlikely to house nearly 800 million people in such a territory. One would have to further assume that, in Nigeria, all advances in technology will be leveraged to have as many children as possible. That’s just not the human experience.

More realistically, the challenge the world will increasingly face in the years ahead is slow population growth. Framed in this way, we should ask ourselves a higher level question: what can we do to more equitably distribute resources which are, increasingly, not scarce but quite obtainable.

–Gregor Macdonald

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Further reading: This 26 October Twitter thread by @Noahpinion on the topic of population. Also, this post by Dave Roberts at Vox: I’m an Environmental Journalist But I Never Write About Population. Here’s Why.

Further charting: Here is an interactive, Datawrapper version of the first chart in this post, using the same timeframe and data.