The UN says nine countries will account for half of the world’s population growth from 7.6 billion in 2017 to 9.8 billion in 2050.
The UN in a projection, named India, Nigeria, the Democratic Republic of Congo, Pakistan, Ethiopia, Tanzania, the United States, Uganda and Indonesia, the report from the UN’s Department of Economic and Social Affairs, as the nine countries.
The UN said that in spite of fertility levels declining in nearly all regions in the world, the group of 47 least-developed countries had a relatively high level of fertility at 4.3 births per woman in 2010 to 2015.
The world body added that in Africa, populations in 26 countries are projected to expand to at least double their current size.
Nigeria is set to overtake the US in population by 2050.
The concentration of population growth in the poorest countries will pose a challenge for the UN’s goals of improving healthcare, education and equality to end poverty and hunger in the developing world.
Meanwhile, Europe’s population is predicted to continue ageing, with the percentage of people aged 60 or older rising from 25 per cent in 2017 to 35 per cent in 2050.
A growing number of countries now have fertility rates below the replacement level that keeps the population level constant, the 10 most populous of which are China, the U.S. Brazil, Russia, Japan, Vietnam, Iran, Thailand and Britain.
The movement of refugees and other migrants will go some way to compensating for dwindling population growth, especially in Europe, but will not fully compensate for the decline, the report notes.