The 2015 Revision of the UN’s World Population Prospects estimates a global 2050 population of 9.7 billion people. That is 420 million more than the UN had estimated as recently as 2010. The incremental rise comes from higher estimates for all continents, especially Africa which goes from 2.2 billion to 2.5 billion.
These figures are all part of the UN’s ‘median variant’ which expects the Total Fertility Ratio (TFR) to decline sharply in Africa from 4.41 children per woman now to 2.96 in 2050. The rise in estimates since the 2010 Revision is due to the realization that TFRs are falling more slowly than expected. The 2010 forecast was for a 2050 Africa TFR of 2.77 instead of 2.96.
All other TFRs of other continents are expected to fall below replacement level of 2.1 and to remain there for decades to come. Population will grow on all continents except Europe where it will decline faster than was thought in 2010. Europe which accounted for 22% of the world population in 1950 is estimated at little over 7% in 2050, and at less than 6% in 2100. The UN sees Germany, Italy, Russia and Eastern Europe losing population while France and the UK gain only modestly.
Finally, note that the population of the Western hemisphere will only grow by 225 million between now and 2050, while the rest of the world grows by 2.1 billion.
See tables below for 2010 and 2015 estimates.