Just an observation;
There are numerous YouTube clips that explain population growth. They factor in: medicine, wealth, education, contraception, movement to city dwelling as factors driving down population growth. These are all historical factors that are assed with hind sight.
None of these models mention the effect of new technology. e.g. Transport and the past restriction and current ability to travel (migrate) as a factor. The other big factor is the media.
From TV to internet, media shows people in the developing countries how much easier/”better” life is in the developed world. Programmes, adverts, films with people in nice cloths, house, and cars (Isn’t that part of what broke down the iron curtain?).
The assumption is that the developing nations continue to develop and the population stays put while it happens. However, with the knowledge and ability that technology brings, why would they waiting for their nations to catch up with the developed nations (one or two generations)?
Would they not travel to where life was “better” now (for them and their children rather than just their grandchildren)?
Assuming it is the educated and wealthy that migrate away, what drives development in the country they have left? Do these countries develop slower, or not at all? Does the birth rate remain high, so breaching the UN’s expected population plateau of 10-billion?
I don’t know the answers, but the models that exist (publicly) are based on historical data and take no account of “what if?” scenarios. Projecting the past forward unmodified is as a bit naïve.
Anyway, global warming, a superbug, WWIII and the meteor of doom are other possibilities that will make this point mute.
