World population forecasts tend to have an error range of +/- 5% in 2030 and +/- 14% in 2050. However, estimates of population for today can have errors in the +/- 2% range and even higher error levels for some countries. It is useful to determine if there is a likelyhood of an over or under count or over or under estimate.
China could have an undercount in its population because people in rural areas are hiding children to avoid the one child policies. Russia could have an official overcount to hide a population drop. Russian policies to increase immigration could mean that forecasted population are too low.
1. China 1,343.24 2. India 1,205.07 3. United States 313.85 4. Indonesia 248.22 5. Brazil 205.72 6. Pakistan 190.29 7. Nigeria 170.12 8. Bangladesh 161.08 9. Russia 138.08 10. Japan 127.3
There has been a trend towards GDP per capita catch up for less developed countries.
If the developed countries have 3% GDP growth each year.
Developing countries that can sustain 6% GDP growth for decades would catch up at about 35% per decade for overall GDP but by less on a per capita GDP basis if they have a growing population. If their population grew 10% then they might have 25% catch up in per capita GDP. Over 4 decades they would catch up about 3.2 times. If they started at $1000 per capita then they would still only be at $3200 per capita in 2050.
Developing countries that can sustain 10% GDP growth for decades would catch up at 1.96 times per decade. This would be 15 times over 40 years. If they started at $1000 per capita then they would still only be at $15000 per capita in 2050.
Fast growing countries that have a plus or minus 2% GDP growth projection error rate can have massive GDP projection errors over decades.
Changes in currency exchange rates would also have a large impact.
India has current problems where perhaps 40-55% of the population have some levels of malnutrition. There is also high levels of illiteracy. This would prevent most of those people from achieving equal per capita income with people in the United States.
Fully catching up the United States in per capita GDP is pretty much impossible for countries like India, Indonesia and Brazil.
The United States would have to completely stop immigration and have a greatly reduced population to enable countries other than China to have a larger overall GDP by 2050.
Significant life extension and robotic technology and permissive immigration would help aging developed countries (Japan, Germany etc…) to maintain GDP levels.