I recently came across a superb lecture on global population growth by the statistician Hans Rosling "Don't panic: the facts about population". Based on the latest UN data, populations in billions are predicted to be:
| 2010 | 2050 | 2100 | |
| America | 1 | 1 | 1 |
| Europe | 1 | 1 | 1 |
| Africa | 1 | 2 | 4 |
| Asia | 4 | 5 | 5 |
| Total | 7 | 9 | 11 |
There is uncertainty in these predictions, for example back around 2000 the UN predicted global population at 9 ± 1.5 billion by 2050, although it seems unlikely that they will be fundamentally incorrect unless there is a cataclysm.
