Globalization: Global Population:

 

Quantitative Estimates

of the Future World Population Decline

 

by Dr. Julio A. Gonzalo¹ and Dr. Manuel Alfonseca²

¹ Escuela Politécnica Superior, Universidad San Pablo CEU, Montepríncipe, Bohadilla del Monte, 28668 Madrid, Spain. Departamento de Física de Materiales, Universidad Autónoma de Madrid, 28049, Madrid, Spain, e-mail: julio.gonzalo@uam.es

² Escuela Politécnica Superior, Universidad Autónoma de Madrid, Francisco Tomás y Valiente, 11. 28049, Madrid, Spain, e-mail: manuel.alfonseca@uam.es

 

Abstract

The extrapolation of the UN world population data up, and including to the first decade of our century, using the UN projections for a low fertility rate, point to a step down in population after 2050, which is analyzed using the rate equation approach. The large increase in world population after 1950 is shown to be due to the increase in life expectancy, rather than to an inexistent increase in fertility rate.

 

Introduction

As pointed out recently by Michael J. Kelly¹ a collapse of global civilization as predicted by Ehrlich² is unrealistic because a balanced assessment of the historical progress being made suggests otherwise. In his words:

The population explosion (and its Malthusian societal disruptions) that Ehrlich FRS predicted for the 1990s has not come about..., and the concerns in this present Ehrlich paper are not tempered by the mounting evidence of the demographic transition that occurs when the majority of people live in cities and have access to education. In Japan, Europe and North America the population, excluding immigration, is in decline. Some studies indicate that a peak of 9 billion people in 2050 will be followed by a decline to a population of approximately 6 billion in 2100—less than that in 2000... and bringing new problems of unwanted infrastructure assets! The UN is revising its future population estimates downward.... If we look at the waste in the contemporary food chain, at the point of growth, in transit to the market and into the homes of consumers, and compound that loss by the amount of food thrown out rather than consumed, we generate the quantity of food to feed the 9 billion today with the systems in place if we were less wasteful and could distribute it...

 

Previous work³ investigated claims (Science, 4 Nov. 1960) that world population would approach infinity in the third decade of the 21^st century. On the other hand, a plot of world population (1960-2010) as given by the UN shows clearly that it will approach a maximum about the year 2050, and then will start going down.

 

Improved solutions to the two complex rate equations describing world population trends have been shown to describe it well from 1950 to 2010 and can be used to estimate it reasonably beyond 2010. As global birth rate (BR) has decreased consistently in those years, a continued exponential growth of world population is certainly not realistic. Current population growth must be entirely due to global increase in life expectancy, i.e. the decrease in death rate (DR). This increase, which has been documented since the middle of the twentieth century, should not be expected to proceed beyond 85 years, as current data show for Europe and the U.S. In fact, the death rate has been growing in Europe and Japan for over a decade, due to the aging of the population.

 

As shown below, a large step-up in population, as what took place during the last century, can be characterized by a significant decrease followed by a subsequent decrease in birth rate.  This was evident in the early fifties, before anti-natalist policies became recommended or enforced by the UN and the governments of the leading countries in Europe, America and Asia. International groups like Planned Parenthood have carried out effective anti-natalist campaigns, intensifying abnormally the natural decrease in birth rate already under way, so that we are now facing a possible population decrease after 2050 with unwonted consequences.

 

A population step-up, followed by a subsequent step-down is in principle describable with the same kind of rate equations used previously (1) to describe an isolated step-up.

Around 1900, the death and birth rates were BR»DR»40´10^-3, leading to a stable population level.

 

Population step down

In ordinary circumstances, a population step-up is driven by an increase in life expectancy, followed (after a certain delay) by a decrease in birth rate. The characteristic time (t) is computed as the inverse of the square root of DR and BR, resulting, after the transient, in a new replacement level at a higher population. The analogous process of a population step-down also begins by an increase in death rate (which of course could, but should not be artificially induced) followed eventually, after a certain delay, by an increase in birth rate until a new stable level is reached. The longer the birth rate delay, the more serious the succeeding population decrease.

 

Our planet is a closed system, in the sense that we do not expect aliens to come to us as immigrants, or a massive migration of Earth people to far away planets. The total sustainable human population on Earth has been estimated² as one order of magnitude larger than the current 7 billion population.

 

Data analysis

Table I shows the world population U.N. data, where the three values in the world DR and BR columns after 2010 are projections corresponding to three different birth rate scenarios: low, medium and high fertility. For the other columns, only the low fertility scenario is shown. Given that the UN data are rounded to the nearest integer, in Table II we have slightly corrected those values, so as to obtain smoother graphics. It can be observed that both death rate (DR) and inverse life expectancy (LE^-1) have decreased simultaneously between 1950 and 2010. Table II shows some computations on the DR/BR values , extended to 2050 using the low fertility scenario. The two computed values are the following:

 

              

 

Table I: U.N. 2012 data (http://esa.un.org/wpp/Demographic-Profiles/index.shtm)

 

 

Table II: Some computations on the smoothed UN data

 

Figure 1 plots the death rate (DR) for the world (1960-2010) as a function of inverse life expectancy (1950-2000). It can be seen that DR seems to be approaching a minimum and may even be on the rise for Europe. This is an inevitable consequence of the fact that older generations are approaching their maximum life expectancy.

.

Figure 1. DR vs LE^-1 (DR delayed by 10 years).

 

Figure 2 shows world population growth rate (GR) for the lower fertility scenario. Figures before 1950 are scattered and unreliable, but they show that GR was significantly smaller than 1% by 1900.

Figure 2. Growth rate vs time for the low fertility scenario. Prediction begins at the right of the dashed vertical line (the 2005-2010 interval).

 

Figures 3 to 5 illustrate the population step-up as a function of time for the three different future scenarios. Figure 3 shows how the population step-up takes place through a pronounced decrease in DR followed, after some delay, by a similar decrease in BR. Figure 3a shows the low fertility scenario, where DR»BR by 2050-2055, a time at which a population step-down could start to take over (see figure 2). Figure 3b shows the same information for the medium fertility scenario, where this effect would be delayed by about 50 years.

 

Figure 4 shows a as a function of time for the three U.N. scenarios. It can be seen that a maximum was reached around 1985 (the population inflection point). The average of this variable between 1950 and 2010 is 2.48. For the low fertility scenario, x becomes 1 around 2050 and its decrease after 1985 is more pronounced than its increase before that date.

 

Figure 5 represents the characteristic time (t) in the same conditions. Its value goes up quite linearly from about 19 years by 1950 to about 40 years by 2010, but is supposed to stop growing by 2005-2010 in the high fertility scenario, and by 2020 in the medium and low scenarios.

Figure 3a. DR and BR vs time for the low fertility scenario. Red: BR; green: DR.

 

         

Figure 3b. DR and BR vs time for the medium fertility scenario. Red: BR; green: DR.

 

Figure 4. a vs time for the three future scenarios. Blue: lower fertility; green: medium fertility; red: high fertility.

Figure 5. t vs time for the three future scenarios. Blue: lower fertility; green: medium fertility; red: high fertility.

 

Figure 6 shows the birth and death rates for the world and Europe between 1950 and 2010, together with extrapolated values for the world according to the three alternative scenarios. For the low fertility scenario, the crossing of death and birth rates is to be expected by 2050, and the expected average of x=BR/DR between 2050 and 2100 would be between 0.75 and 0.85, implying a substantial decrease for the world population around 2010.

Figure 6. DR and BR vs time for the World and Europe. Dashed lines: Europe. Full lines: world. Blue: lower fertility; green: medium fertility; red: high fertility. Predictions begin at the right of the dashed vertical line (the 2005-2010 interval).

 

During the step-up, the world population can be represented¹ by the following equation:

                                                                    (1)

where  (replacement level of the world population around 1900), , t_i = 1985 (inflection time), and t_i = 33 years, resulting in .

 

During the step-down, we will consider two cases: x=BR/DR=0.85 and x=0.75. The appropriate equation for the step down would be:

                                                                     (2)

where  (world population around 2050), ,  (estimated inflection time for the step down), and , for ; or  for . This implies substantial world population decreases of almost half a billion (460 million) and about twice that (810 million) by 2100, respectively.

 

We can now estimate, using figures 3-5, what would have been the step-up in population in the interval 1950-2010 if a natural decrease in birth rate would have been allowed, i.e. a continuation of the birth rate decrease which had been taking place during the sixties and early seventies, before drastic anti-natalistic policies (chemical contraceptives, induced abortions, amoral sexual education and the like), supported by international pressure groups such as the UN, Planned Parenthood and the governments of the leading countries in Europe, America and Asia, had a substantial impact on world population trends. Introducing the pertinent changes in equation (1), we get table III.

 

Table III. Comparison of the effect of anti-natalistic policies.

 

 

Conclusions

We can reach the following conclusions:

·       The exponential growth in world population assumed for years by the UN and the leading countries of the world is unrealistic.

·       Human population trends should not be manipulated under the false assumption that anti-natalistic ideologues know better.

·       Today the world is not overpopulated and is unlikely to be so in the foreseeable future. In Asia, the most populated continent, many countries (Taiwan, South Korea, Japan, Hong Kong, Singapore...) have reached several times the average Gross National Income for the world.

·       Extrapolating present trends shows that total world population may reach a maximum of 7.74 billion by 2050, and by the end of the current century it may have decreased by half a billion to a billion.

·       Assuming that the relatively smooth natural decrease in birth rate underway by the mid-seventies had continued all the way towards a new replacement level, the estimated population maximum would have reached 8.4 billion by 2065, rather than 7.73 billion by 2050, and the now expected step-down by 2100 could have been avoided. Therefore the anti-natalistic policies supported by the UN should be reconsidered.

·       The population rising during this century (1950-2050) is due to the high and sustained decrease in death rate (and the corresponding high increase in life expectation) rather than an increase in fertility that actually never happened.

 

References

 

1.     Kelly, M.J., 2013. Why a collapse of global civilization will be avoided: a comment on Ehrlich & Ehrlich, Proc. R. Soc., V.282, I.1802, DOI:10.1098/rspb.2013.1193.

2.     Ehrlich, P.R., Ehrlich, A., 2013. Can a collapse of global civilization be avoided? Proc. R. Soc. B 280, 20122845, DOI:10.1098/rspb.2012.2845.

3.     Gonzalo, J.A., Muñoz, F.F., in press. Prospects of world population decline in the near future.

4.     Gonzalo, J.A., Muñoz, F.F., 2012. Using a rate equation approach to model world population trends. Simulation 89(2), 192-198, DOI:10.1177/0037549712463736.