Saturday, December 01, 2018

No overpopulation threat

Overpopulation has proven to be a persistent fear — even as the evidence for it grows weaker and weaker.

There is no denying that the planet's current population is increasing. It’s easy to imagine the earth adding another billion inhabitants every 12 years or so in perpetuity — easy, but wrong. The world’s population growth will only continue its breakneck pace if fertility rates don’t drop. But that is exactly what’s happening. 

Total fertility rate,(TFR), the number of babies the average woman will bear over the course of her life, has decreased from nearly 5 in 1950 to 2.5 today. For context, a TFR of 2.1 is known as the replacement rate, or the rate at which the population remains steady. But this decline in TFR is more drastic than it seems at first sight. In regions the UN considers “more developed” (Europe, North America, Australia, and Japan), TFR declined from 2.8 in 1950 to under 1.7 today. Demographic momentum keeps these populations stable or growing for now, but in the coming years, the developed world will see their native-born populations shrink. Japan is already undergoing this shrinkage.

Now, the “more developed world” comprises just 17 percent or so of the world’s population, so this shrinkage will be more than cancelled out by growth elsewhere, where TFR remains above replacement. But fertility rates are declining even faster in the less developed world: from 6.06 in 1950 to under 2.6 today. Certain countries, mainly African nations such as Niger and Angola, maintain TFRs above 6, but these rates should follow the same pattern and fall precipitously as the countries develop. The case of Latin America is illustrative. Last: “The average fertility rate for Latin America in the 1960s was 6 children per woman; by 2005 that average had dropped to 2.5. Within a decade or two, every single country in Latin America will likely have a fertility rate below that of the United States.

The UN foresees a continued increase throughout this century, nearing stabilization around 11 billion in 2100. As far as rates of increase go, that’s much slower than our pace over the previous century, when world population nearly quadrupled. But that could still be a massive overestimation. An analysis by Sanjeev Sanyal, formerly of Deutsche Bank and now Principle Economic Adviser in India’s Ministry of Finance, forecasts that global population will peak in 2055 around 8.7 billion people, and decline to 8 billion by 2100.
And Sanyal’s estimate seems more credible given the UN’s history of overestimating fertility rates.

 The UN’s 2010 forecasts assumed nearly every industrialized nation would see its TFR increase to 2.0 over the next 70 years, magically settling near the replacement rate. This, despite no country ever transitioning back to replacement-level fertility (for any five-year period) once falling below it. The UN has since revised downward their predictions of future fertility rates, but their past record does not inspire confidence. Skewed gender ratios in China and India (i.e. an overabundance of single males) also suggest fertility rates will come in lower than raw population counts imply in the world’s two most populous nations. And even if the world decides it wants to re-inflate fertility rates, government efforts to do so have not met much success (though it will be interesting to see whether China’s attempt to reverse its one-child policy bucks this trend). In short, if fears of a population bomb hardly made sense in the 1970s, they make even less sense now.

The earth’s population will increase over the next few decades, but we know what that entails. The world has coped with not just population growth but a population explosion pretty well, despite the dire warnings of doomsayers from Thomas Malthus to David Attenborough What’s more worrying is the unknown. As Last writes, “Since the Industrial Revolution (at least) there is no model for a country experiencing a sustained, structural shrinking of its population” — a fate soon arriving for the developed world, and if Sanyal’s analysis is correct the rest of the world too. In a contest of horrors, the onset of a unique experience in the history of modern man would seem more concerning than the fevered fears of Paul Ehrlich.

From here

Global Fertility Rates 1960-2016 - World Bank

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