The world's population will break through the 8 billion mark in 2023, there are more men than women, and next year the number of over 60s will top 1 billion for the first time, according to the latest findings and forecasts from the United Nations annual population survey.
More than half of the global population growth by 2050 will come from sub-Saharan Africa, where fertility rates will persist at levels far higher than in the rest of the world, the UN predictions released on Wednesday show.
Half the growth in numbers of people will come from just nine countries: India, Nigeria, Democratic Republic of the Congo, Pakistan, Ethiopia, Tanzania, the US, Uganda and Indonesia. By 2050 seven of the world's 20 most populous nations will be African.
By contrast, all European countries now languish with fertility rates below replacement level, meaning that populations will inexorably decline without large-scale immigration.
"In some countries with low levels of fertility and ageing populations ... a net inflow of migrants has been the primary source of population growth and in some cases has averted a decline in population size," noted John Wilmoth, director of the UN's population division.
Eastern Europe is likely to be particularly badly affected by population trends, with numbers likely to fall more than 15% in Bulgaria, Croatia, Latvia, Lithuania, Poland, Republic of Moldova, Romania, Serbia and Ukraine.
The UN study also found that there are more men than women globally (102 men for every 100 women), and that the number of people over 60 will top 1 billion in 2018 - and 2 billion by 2050. Children under 15 years make up about one quarter of the world's inhabitants.
The median age of the world's population is 30.