I have at times written about population growth control, sometimes humorously and at others with seriousness (https://trenzpruca.wordpress.com/2012/11/14/testosterone-chronicles-1/, https://trenzpruca.wordpress.com/2012/08/21/men-women-and-rebecca-solnit-is-10-mellenium-of-subjegation-enough/, https://trenzpruca.wordpress.com/2016/02/08/what-the-world-needs-now-is-fewer-men/), Most of the time I have connected it up with the climate crisis, as did Rachel Carson, Paul Ehrlich and ZPG in the 1960s and 70s. Even then, in a few countries around the world, population growth began to slow down or even halt due to lower fertility rates. For example, the total fertility rate in the US dropped from an average of 3.4 children per woman in the early 1960s to 1.8 by 1975. The doubling time of US population rose by 14 years between 1968 and 1975, and natural increase dropped from an annual growth of 1.1 percent to 0.9 percent. Nevertheless, the US population continued to grow at a faster rate than warranted by the drop in fertility rates due to immigration primarily from Asia and Mexico, Central and South America and the simultaneous increase in life expectancy.
More recently a new paradigm has emerged, due primarily to the effects of the emancipation and education of women. In 1950, women were having an average of 4.7 children in their lifetime. By 2017 researchers at the University of Washington’s Institute for Health Metrics and Evaluation found the global fertility rate nearly halved to 2.4 – and projected it will fall below 1.7 by 2100. (https://www.bbc.com/news/health-53409521,)As a result, these researchers expect the number of people on the planet to peak at 9.7 billion around 2064, before falling down to 8.8 billion by the end of the century.
According to the Washington University projections, 23 countries can expect their populations to halve by the end of the century, . Some you’d expect: Japan will shrink from 128 million in 2017 to 53 million, Italy, Spain and Portugal also are expected to lose half their populations. Others might surprise you: the number of Thais and South Koreans is forecast to halve too, and China will come very close to a halving – from a peak 1.4 billion to 732 million. (https://www.elfac.org/the-world-is-heading-for-a-population-crisis-but-not-the-one-it-was-expecting/)
This drop according to the researchers had little or nothing to do with sperm counts or the usual things that come to mind when discussing fertility. Instead it is being driven by women becoming educated, entering the work force, and having greater access to contraception, leading them to choose to have fewer children. In many ways, the falling fertility rates are a success story.
The study projects that the number of under-fives will fall from 681 million in 2017 to 401 million in 2100. The number of over 80-year-olds, however are expected to soar from 141 million in 2017 to 866 million in 2100.
Currently, fertility is below replacement among those native born, and above replacement among immigrant families, most of whom come to the United States from countries with higher fertility. However, the fertility rate of immigrants to the United States has been found to decrease sharply in the second generation, correlating with improved education and income.[ “How Fertility Changes Across Immigrant Generations.” Research Brief #58, Public Policy Institute of California, 2002.] In 2019, US TFR continued to decline, reaching 1.71.[“Expect a baby bust, not a boom, from the coronavirus pandemic”. Washington Post. 2020-06-16.]One would think this is a good thing, yes? Well, not so fast.
Although the potential worldwide fall in fertility rates may appear beneficial in dealing with some of the effects of climate change and loss of biosphere diversity, consider that the study mentioned above also projects the number of under-five-years-olds falling by over 1/3, from 681 million in 2017 to 401 million in 2001, while the number of 80-year-olds are projected to increase from 141 million in 2017 to 866 million in 2001, a sixfold increase in the 80 and older population. According to the OECD, the over 80-year-old cohort is expected to double within the next 30 years:
The growth in the share of the population aged 80 years and over will be even more dramatic… On average across OECD countries, nearly 5% of the population was 80 years old and over in 2015. By 2050, the percentage will increase to more than 10%. In Italy, Spain, Portugal, and Germany, the proportion of the population aged over 80 is expected to more than double between 2015 and 2050. The rise will be even faster in Korea, where the share of the population aged over 80 years will grow from 3% to 14% over the next four decades.
(Note the University of Washington’s projections place the percentage of the over 80s to be 15% or more of the world population by the end of the century.)
It should also be noted that we are talking about those people already living longer than the current average human life span living even longer. These figures do not take into account the current and future advances in geriatric medicine extending life expectancy of all and of over 80s specifically. The current life expectancy of an 80 year old is less than 10 years. It has increased by about a year or more in the last decade. Due to the expected advances in geriatric medicine it can be presumed to increase at the same rate or more for the next two decades or so..
Note: the percentage of Americans over 65 has increased from about 4% in 1900 to about 14% in 2020. I assume the percentage increase of the over 80 population in the US to have been equal to and probably larger than that.
Before proceeding to the potential social, economic, and political effects of the falling fertility rates, a little bit of history. Someone recently popularized the term, The Long 20th Century. It began in 1870 with the explosion of science. Engineering and commercial prowess pushed the Industrial revolution into high gear. It ended in 2016 with the collapse of the world order that had shepherded the brief explosion of intellectual scientific and commercial success along with the shocking cruelty, human slaughter and environmental degradation that marred those successes. It has been perhaps the most consequential period in human history since the Toba volcano eruption reduced the human population to a few thousand individuals 70,000 years ago.
During the long century, medical science perhaps advanced more than any other science except possibly for physics. From 1870 until a little after mid-century, medical advance focused on the maladies of children remarkably ending many of the scourges that had hounded humanity for over 100,000 years. To a great extent these advances in the survivability of infants and children are responsible for the explosive world-wide population growth that began in mid-century and has continued until today. More recently the focus of the medical community has shifted to addressing the problems of the elderly thereby mitigating to some extent the effect of falling fertility rates on population growth.
So, assume we miraculously come through to the impending climate catastrophe of the next 30 years or so with our economy intact and our societies relatively vigorous, what should we expect if worldwide fertility rates continue to decline below replacement level and the relative number of the elderly in our societies continue to increase?
Well, the first thing we should expect is to be surprised at quantity and scope of effects we did not expect. There are, however, a few additional things we should expect:
1. Massive and unpredictable political conflicts between the over 80 cohort and the younger cohorts over economic resources.
2. Since GDP does not directly measure population growth but increases in population generally are reflected in a nations GDP growth, falling populations and growing unproductive aged populations would be reflected in lower national GDP and per-capita GDP numbers (and similar statistics). This does not necessarily mean a worldwide trend to increasing poverty, but without the development of greater efficiency in production, transportation, and communication it would be likely.
3. Labor supplies will decline precipitously as populations age and fall at the same time.
4. Total energy use may fall as populations decrease and age. Energy use per capita, which over the past 100 years has doubled while total energy use has increased twelve-fold, probably will remain stable or fall, but may stagnate or perhaps even decrease as capital investment in energy and energy technology collapses.
5. A potential worldwide slowing of individual, national and international economic growth, beginning in about 2160 and extending through the end of the century will generate new pockets of poverty, population movements and increased political turmoil, ( all exacerbated by the lasting impacts of climate change even if we manage to address it in time)
It cannot be overemphasized that within the next 20 years we will be hit with at least two major worldwide crises. One, climate change, which for the past 20 years we have struggled to address and failed so far to do so. The second, the adverse effects of a worldwide collapse in fertility rates and the aging of its population, has not yet even been recognized as a potential problem.
True, the Climate Crisis is probably existential and to some extent fertility and aging crisis may alleviate some of its impacts, Nevertheless, the economic and political implications of the latter promises no bed of roses for the future of humanity even if we do survive.
Note: In 1916, Michael A. Genovese wrote about the same emerging problems (http://worldpolicy.org/2016/06/13/too-few-and-too-many-the-looming-population-crisis/). See also, https://www.un.org/en/global-issues/ageing.