Birth rates in Europe and the US are below replacement level. Our populations incense from immigration, right? From what I've read when the 3rd world gets enough food and money they too will drop below replacement level. So what's it gonna be like with a ever shrinking population? Wouldn't this be deflationary?
I think human population growth will plateau only with Malthusian barriers to growth: lack of fresh water, lack of energy, lack of food, epidemics, natural disasters, wars, and so on. The established estimates that assume populations will decrease their growths and plateau as they become richer assume racial egalitarianism, where equatorial populations are assumed to be genetically the same in their sexual behavior as northern populations. But, it is a hypothesis that has seemingly failed when examining the descendants of Mexican immigrants to the USA: third-generation descendants of Mexican immigrants have about the same or higher fertility rate as their parents and grandparents, even while being richer and more highly educated (i.e.
“Mexican-Origin Fertility: New Patterns and Interpretations,” 2000). As fertility rate among populations seems to be largely a function of ancestral distance from the equator, I favor J. Philippe Rushton's theory that a higher fertility rate was a means for a gene's survival in a dangerous chaotic environment with plentiful resources--many children would die but the genes would live on--whereas northern populations adapted to their cold scarce consistent environments through parental investment of fewer children and greater intelligence. As the equatorial environments have industrialized and become safer, this means the equatorial populations will continue their high fertility rates but without the high death rate, and they will out-populate the northern populations, even while they become richer, until they hit those deathly Malthusian barriers. The world population will eventually plateau, but it will not be by choice and it will not be pleasant. Global warming will exacerbate the problems, as the killer heat waves, storms and droughts will affect equatorial climates the most, and cold northern climates will only become warmer and more human-friendly.