Many countries in sub-Saharan Africa and some in Asia continue to experience rapid population growth and high fertility rates, the 2020 World Population Data Sheet released by the Population Reference Bureau (PRB) stated.
It said the population of 25 countries including Ghana, is expected to at least double between now and 2050.
The Data Sheet copied to the Ghana News Agency said older adults ages 65 and older now account for nine per cent of the global population, in part because of declining fertility rates.
In 91 countries and territories, nearly 45 per cent of the world's population total fertility rates were below replacement level, the average number of children at which a population exactly replaces itself from one generation to the next in the absence of migration.
And in 21 countries and territories, including several that have suffered devastating loss during the COVID-19 pandemic, people ages 65 and older account for at least 20 per cent of the population with this trend most pronounced in Europe and Asia.
Published since 1962, PRB's annual World Population Data Sheet tracks global population data.
This year's edition provides 24 population indicators for more than 200 countries and territories.
Users can also explore key trends through an interactive map.
Jeff Jordan, PRB President and CEO said "As the experience with the COVID-19 pandemic has shown us, population changes such as aging and rapid urbanisation are important factors for countries to consider as they plan for future disease outbreaks, long-term health care needs and other developments.
" "PRB's World Population Data Sheet provides objective data and analysis policymakers need to make.
" Among the key findings for 2020 are the world population is projected to reach 9.
9 billion by 2050, an increase of more than 25 per cent from 2020.
The global total fertility rate is 2.
3 births per woman, while the replacement level is 2.
1 births per woman.
Western Europe and Southern Europe have the largest shares of people ages 65 years and older (21%), while sub-Saharan Africa has the smallest share (three per cent).
It said that Angola and Benin are projected to grow by at least 150 per cent of their current population between 2020 and 2050, while Niger's population is expected to increase by almost 175 per cent.
Thirty-eight countries and territories, including Armenia, Germany and South Korea, are projected to have a smaller population in 2050 than in 2020.
On fertility, it said Niger had the highest total fertility rate (7.
1 average births for each woman), followed by Mali (6.
3) and the Democratic Republic of the Congo (6.
Some of the lowest total fertility rates are in South Korea (0.
9), Taiwan (1.
0) and Singapore (1.
The Data Sheet noted women's life expectancy at birth is highest in Hong Kong (88) and lowest in Central African Republic (55).
Life expectancy at birth for men is highest in Australia (83) and lowest in Central African Republic and Lesotho (51).
Among the regions, Eastern Europe has the largest gap in life expectancy between men (69) and women (79).
Sub-Saharan Africa has the youngest population of any region, with 43 per cent of its population under age 15.
In contrast, 14 per cent of Southern Europe's population is under age 15.
At 84 per cent, South America has the highest percent of the population living in urban areas of any region with 12 countries and territories, at least 50 per cent of the population lives in cities with a population of one million or more, including Republic of the Congo (63%), Australia (62%) and Israel (61%).