The population bomb goes PFFT

 kw: book reviews, nonfiction, population, demographics, futuristics

As Yogi Berra (probably) said, "Prediction is hard, especially about the future." That doesn't seem to stop anyone. When I was growing up, projections of future gloom and doom, particularly about population, were periodical literature. Paul Ehrlich's book The Population Bomb was a best-seller in 1968. The Club of Rome issued Limits to Growth in 1972.  As recently as 2015 we have The End of Plenty by Joel Bourne. Much further back, the "granddaddy of gloomy prophets" is probably Thomas Malthus, with An Essay on the Principle of Population as it Affects the Future Improvement of Society, in 1798.

All of these based their predictions on the fact that population grows exponentially while agricultural productivity grows linearly. Each author called on us to expect disaster within a generation. However, 8 or 9 generations have passed since Malthus wrote, and about 2 generations since Ehrlich. Not only haven't we starved to death, the population has risen from just under a billion in 1798 to almost 7.8 billion today (late 2020), yet the proportion of that population who are starving is at a historic low, and there is actually abundant food for all, but corrupt governments and failed states are responsible for every food shortage that currently exists.

What happened to all the predictions? This chart, from The World in Data, sums up one factor nicely:

The curves after 2019 are a projection. Note the peak of the pink curve, which shows the global rate of population growth. That peak was in 1968, when Dr. Ehrlich's book was published. I wonder if he takes credit for the dramatic reduction in growth rate that followed. Had a growth rate of 2.1%/year (actually 2.08%) continued for the next 52 years, world population today would be not 7.8 billion but nearly 10.4 billion.

However, it is critical to understand that 2.1%, or any other figure on this chart, is not the birth rate, but births minus deaths. In those years, birth rate was around 3.7%/year, but that is not the criterion that economists use to calculate future population. That is fertility, or the number of births per woman, a lifetime figure. Projecting the chart above further into the future, its authors would conclude that the global population growth rate would reach zero about the year 2130, and then go into negative territory, meaning that population would begin to fall below a peak that they expect to be just above 11 billion.

The fertility of the whole world expected by the chart's authors in 2130 would be 2.1 births per woman, which is called "replacement rate". If nobody died before adulthood, a fertility of 2.0 would provide full replacement, but of course some do. In a much safer world, perhaps replacement fertility could be 2.05 or less.

The second factor is, I would say, a series of "white swans" (as opposed to "black swans", which are unpleasant surprises) in agriculture. In the Parable of the Soils (Matthew 13:1-23), Jesus speaks of the "good ground" yielding fruit 30-, 60-, or 100-fold. Thirty-fold harvests were good for the time, and 60- to 100-fold harvests must have seemed incredible to the disciples. Grain harvests today exceed 300-fold. That is just one element in the agri-revolution that can feed 8 billion right now. Another is factory farming; some hate it but you can't argue with the results. Land that once couldn't be farmed, is now arable, cranking out those huge harvests.

One final point before getting to the current book. The wiggles in the growth curve above represent generational trends. The upward burst after 1910 shows the effect of public health measures that led to safer water and less cholera and malaria; a steepening in the 1940's is the "baby boom" that affected mainly the West; the near-plateau about 1950-55 shows the "birth dearth" after decolonization and the breakup of the British, French, Portuguese and other empires; the "pop-up" that peaked in 1968 and then fell just as rapidly shows the twin effects of the X Generation's births followed by "the pill"; and then the blips in the 1980's and early 2000's are late "echoes" of the Baby Boom, which produced the Millennials (Y Generation) and the Z Generation. But the continuing trend of lower growth rate remains to be explained, and that is the job of today' authors.

Authors Darrell Bricker and John Ibbitson are not economists, but they think like economists. Their book Empty Planet: The Shock of Global Population Decline analyzes the data used by the authors of the above chart, and even more the data and reports published by the United Nations, on the population trends that the U.N. expects for the rest of this Century. To be blunt, Bricker and Ibbitson claim the above chart is incorrect, that the growth rate is most likely to fall to zero and below by about 2050, and that world population will barely exceed 9 billion in that year, and perhaps not even that. They expect world population in 2100 to be close to what it is today, or a little less, and that it will continue to fall.

They base their contentions on a thorough study of trends in many regions and countries. The biggest factor in fertility is education, particularly education of women. The big trend that underlies access to education is urbanization. In 2007, for the first time, more than half the world population lived in cities on in major urban areas. By 2050, this proportion could reach 2/3 (67%) or more. The US and other Western nations hit 50% in the 1920's. Quite a number of countries, mostly smaller ones, are 100% urban, which means they import all their food.

The two biggest countries, by population, are China and India. Chinese urbanization is 61.4% as of early 2020, and India's is 34.9; both are rising fast. Urban, educated people have low fertility; in nearly all nations with large urban populations, fertility is between 1.5 and 1.9. Even in rural areas, which show higher fertility, education is spreading such that there are few places with fertility greater than 3.

The authors write of many things, but emphasize just a few: educated women learn how to control the number of children they have and more of them aspire to a career, so they put off having children, which also reduces the number of children they might bear; and while children on a farm are a benefit—grow your own farm workers!—in a city they are unproductive mouths to feed and their post-secondary education is very costly. For urban people, small families are a survival strategy. Talk to ten millennials; it will be hard to find more than two who think they will have any children, and certainly not before age 30 or 35.

What will happen in the long run? Let us suppose that the year 2100 is ushered in by just 7 billion earthlings, and with a fertility well below replacement, in the range of 1.6, population will continue do decrease. It's not a bad picture, actually. There will be less pollution, global warming will be (or will soon be) a thing of the past, and less of the Earth will be needed for farmland.

Until then, for some countries at least, immigration can ameliorate the problems of an aging population. But eventually there will be few immigrants. However, is decreasing population a disaster, as the authors claim? The biggest problem with a decreasing population is that it is an aging population, and old people need more services, and not just medical. When there aren't enough younger folk available to perform those services, then what?

I expect a "gig economy" to arise for the semi-retired. The healthy ones can do things for those who need it (or are willing to pay for things they just don't want to do). For example, we have a neighbor, a widow in failing health, aged 81. She has a caretaker to lives with her part of the time, for a few days at a time, a woman aged 83 in robust good health! If my wife and I get too frail (or too fed up) to mow our lawn any more, we might employ a lawn care company, or we might look on Craigslist or a similar place for a retiree who likes mowing lawns for a fair price. He or she may be slower at it than the young fellow with a 48-inch riding mower, but I bet more careful. In their dotage, my parents employed a gardener who was older than they, but healthier. I could go on…

Every book I've read on these subjects is based on the premise that continued growth is a requirement for economic health. Where are the economists who are planning what is needed for a future in which the "growth rate" of a country's or planet's GDP is negative? We do have a couple of points of reference. One is the Black Death that removed a third of the population of Europe. Once the survivors got everyone buried and began to pick up the pieces, they found lots of land and "stuff" left behind for the taking, and there was an economic boom. The current Covid pandemic isn't likely to have nearly as great an effect (death rate overall is less than 1%, not 35%), and we don't expect any sudden drop in population to disrupt society the way the Black Death did. With a slower, gradual decrease we can adapt, and it is likely that we are adaptable enough to adjust and thrive.

One production value I must commend: the end notes are all references, with hardly any "extended explanations." I prefer that; if an author has something worth writing about, it is worth putting in the text. When I find that a book's end notes are full of added material, I put a second book mark there, so I can refer to an end note on-the-spot to see what else was written, and read it while the referring material is fresh in my mind. I prefer not to have to do that.