The United Nations said that the world population is expected to reach 8.6 billion in 2030, and to hit 9.8 billion by 2050, despite nearly universal lower fertility rates.
The world population is now at least 7.6 billion, up from 7.4 billion last year, spurred by the relatively high levels of fertility in developing countries, revealed World Population Prospects: The 2017 Revision.
"With roughly 83 million people being added to the world's population every year, the upward trend in population size is expected to continue, even assuming that fertility levels will continue to decline," said the UN Department of Economic and Social Affairs, which produces the report.
The lower fertility rates are resulting in an ageing population, with the number of people aged 60 or over expected to more than double by 2050 and triple by 2100, from the current 962 million to 3.1 billion, the report noted.
The population of India, which currently ranks as the second most populous country with 1.3 billion inhabitants, will surpass China's 1.4 billion citizens, by 2024, the report predicted.
By 2050, the third most populous country will be Nigeria, which currently ranks seventh and is poised to replace the US.