World population estimates from eleven respected population authorities instantly reveal some obviously preposterous numbers. These folks are prone to give ten decimal point accuracy on subjects where they probably have two decimal point accuracy on their data, at best. For example, the claims for the world population for the year 2005 by the United States Census Bureau (USCB): 6,456,443,080; Population Reference Bureau (PRB): 6,477,000,000; UN Department of Economic and Social Affairs (UN): 6,512,276,000; HYDE: 6,464,751,609. Now, after seven years their data should all be in and fully tabulated so why the 6,512,276,000 minus 6,456,443,080 equals 55,832,920 difference? That is almost the population of Italy, or UK or France and I suspect a country of that size would be annoyed if there population was expected to suddenly vanish. There are 242 countries in Wikipedia’s list by population and Italy is 35th in size, so 242 minus 35 equals 207 countries smaller than the missing number of people between the two authoritative estimates. And that is for a year that is fully and carefully counted.
It really becomes preposterous when these population authorities speculate about the distant past and the not too distant future. The different authorities at least leave the population estimate numbers rounded more broadly. 1AD = 170,000,000 to 300,000,000 people, even though their numbers are wildly different.
The USCB claims to know the exact number of people there are on Earth, to the individual, for the recent years. The PRB rounds out to the million but that is still four significant figures. The UN rounds to one thousand persons which is seven significant figures. The HYDE goes all the way with ten significant figures. But when the claim to accuracy goes off into the future USCB’s claim is still accurate to the individual. This is nonsense multiplied by nonsense and again multiplied by nonsense and called precision. The UN sticks with the accuracy to one thousand people in 2050, which could more accurately be called nonsense multiplied by nonsense. The HYDE rounds up to a million which would be terribly optimistic even for carefully controlled population data collection of the entire population, which is very doubtful because there was a difference fifty five times greater between authorities for the best known year, 2005. But, the projection forty years into the future to the year 2050 with that kind of accuracy is hallucinatory. Of course the USCB might be accurate to the individual, but the likelihood of that is less than one in a billion. The chart below shows there guess to have ten billion different from high to low, but even those numbers don’t include a major problem.
A more accurate way of stating what they know would be to say the population of Earth in 2005 was 6.5 billion +/- 0.1 billion. It might be in fact more realistic to say 90% chance the population was 6.5 billion +/- 0.2 billion. However, the speculations about the year 2050 are contingent on simplistic projections based on current trends, but with accuracy so modest for even what the current populations really are and even more speculative projections as to what the populations were even forty years ago it is getting questionable to even speculate to one decimal point accuracy forty years in the future.
The UN projects somewhere between 15.8 and 6.2 billion as the population for 2050, but — and that is a very, very big but — even as wide as the top to bottom assessments it assumes business as usual. With global pollution of all sorts and resource depletion of all sorts and the well documented history of humans waging all out wars every once in a while, the disruptions could easily drop the population to below what was existing when I was born, which was much closer to two billion. The low UN estimate of 6.2 billion may well be exceedingly optimistic. Even with that much smaller population back then, and therefore much less stress on our planet before 1950, we still had two world wars.
The above chart is possible in a world with atomic weapons being used in repeated wars. However grim a chart like that might be there is the likelihood that life for most people will be good right up to the last day. Also, as the world becomes totally connected on the internet and becomes a unified one world family that we will choose to behave responsibly and stabilize our situation.