Updated UN data on the world population

In a post published in this blog in December 2015, Julio A. Gonzalo and I analyzed the data on the world population provided in 2012 by the UN, along with their future forecasts until the year 2100. A few months ago, the UN has updated those data and forecasts with the figures available in 2019. As seven years have elapsed, it is possible to compare the forecasts made in 2012 with the real situation just now.

Data/forecasts for 2019	2012 forecasts			2019 real data
	Low birth rate	Medium birth rate	High birth rate
Birth rate	16	18	21	18,5
Death rate	8	8	8	7,5
World population (millions)	7487	7640	7793	7713
Life expectancy	71,03			72,28

When comparing data with forecasts, we must bear in mind that in these seven years the UN has improved the accuracy of the measurements. If in 2012 they approximated all figures to the nearest integer, they now dare to add a decimal digit. If we take this into account, we’ll see that the real data closely approximate the forecasts based on a medium decrease in birth rate. The forecasts of a faster decline (low birth rate) have not been met, nor those of a slower decline (high birth rate), whose figures were clearly higher than the current ones. On the other hand, world life expectancy has grown a year longer than expected, which explains that the mortality rate is a little lower, and that the world population has grown to about 7700 million, rather than 7640.

If we look now at future forecasts, we’ll see that things have not changed much, although they are slightly different.

Forecasts for	2050
Scenario	Low BR		Medium BR		High BR
Forecasted in	2012	2019	2012	2019	2012	2019
Birth Rate	11	11,6	15	14,6	18	17,5
Death Rate	11	10,1	10	9,4	9	8,7
World population	8342	8907	9551	9735	10868	10588
	2012			2019
Life expectancy	75,9			76,77

Forecasts for	2100
Scenario	Low BR		Medium BR		High BR
Forecasted in	2012	2019	2012	2019	2012	2019
Birth Rate	8	7,7	12	11,6	16	15,5
Death Rate	15	16,2	11	11,2	8	7,9
World population	6750	7322	10854	10875	16641	16000
	2012			2019
Life expectancy	81,79			81,70

Figure 1

It will be noted that long-term forecasts (for 2100) have barely changed compared to those made in 2012. Those of 2050 have undergone touch-ups, the most important of which is the forecast that, with the low scenario birth rate, the world population will reach its maximum by 2055, when in 2012 that maximum was expected by 2050. A delay of 5 years has been introduced in that forecast.

Figure 1 shows the historical and expected evolution for the birth rate (red curve) and death rate (green curve) for the low birth scenario. The point where both curves intersect corresponds to the moment when the world population would reach its maximum. From that point on, the mortality rate would exceed the birth rate and the world population would begin to decrease.

Figure 2

Figure 2 shows the same curves for the medium birth scenario. Note that in this case the world population maximum would be reached in the first years of the XXII century.

Figure 3

Figure 3 presents the past and expected evolution of the birth rate in the three scenarios considered by the UN. It is easy to see that the high birth rate scenario is unrealistic, as it assumes that from now on the birth rate will grow again (after a continued decline since 1950) and will remain almost constant in its current value ​​for the rest of the century. The medium birth rate scenario seems the most plausible, assuming that the trend of the last 20 years will continue in the future. The low birth rate scenario is also not unlikely, since it is based on a possible repetition of the steep decline that took place between 1990 and 2000.

Of course, all these forecasts assume that in the next 80 years there won’t be catastrophic events, such as nuclear wars, terrible pandemics and other unpredictable natural phenomena that would reduce significantly the world population.

In any case, the updated UN data don’t change the situation significantly. The conclusions of the post in this blog cited above, as well as those in this other post about life expectancy, remain the same.

The same post in Spanish
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Manuel Alfonseca