The world population will reach 9.9 billion in 2050, increasing by 33 per cent from an estimated 7.4 billion now, the latest report from the Population Reference Bureau (PRB) has predicted.
If the assumptions underlying 2050 projections by the PRB's World Population Data Sheet are applied to subsequent years, the world population would hit the 10 billion mark in 2053, with set to Asia gain about 900 million to 5.3 billion.
"Despite declines in fertility rates around the world, we expect population gains to remain strong enough to take us toward a global population of 10 billion," said Jeffrey Jordan, president and CEO of PRB.
"Significant regional differences remain, though. For example very low birth rates in Europe will mean population declines there while Africa's population is expected to double," said Jordan.
PRB's projections show Africa's population will reach 2.5 billion by 2050, while the number of people in the Americas will rise by only 223 million to 1.2 billion.
Europe registers a decline from 740 million to 728 million. Oceania (which includes Australia and New Zealand) would rise from 40 million to 66 million.
The Data Sheet's midcentury population projections indicate that the combined population of the world's least developed countries in the world will double by 2050 to 1.9 billion.
The population in 29 countries will more than double.
Nearly all of these countries are in Africa. In Niger, the country with the highest birth rate, the population will more than triple.
The data showed that, 42 countries will register population declines. These countries are scattered throughout Asia, Latin America and Europe.
Some European countries will post significant declines, such as Romania, which is projected to have a population of 14 million in 2050, down from 20 million today, researchers said.
The population of the US will be 398 million, up 23 per cent from 324 million today.
According to the Data Sheet's estimates of current population, over 25 per cent of the world's population is under 15 years old. The figure is 41 per cent in least developed countries and 16 per cent in more developed countries.
Japan has the oldest population profile, with over a quarter of its citizens older than 65. Qatar and the UAE are at the other end of the spectrum, with each having only 1 per cent over 65.
The top ten fertility rates in the world are in sub-Saharan African countries, with nearly all above 6 children per woman, and one topping seven.
The fertility rate in the US is 1.8 children per woman, down from 1.9 in 2014.
Thirty-three countries in Europe and Asia already have more people over age 65 than under 15.
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