From the Inter Press Service, UN beat writer Talif Deen takes a look at some of the trends behind the ever expanding population.
The world's five most populous countries are China (1.3 billion), India (1.2 billion), the United States (310.2 million), Indonesia (242.9 million) and Brazil (201.1 million).
A new study titled "Africa's Demographic Multiplication", released last month and commissioned by the Washington-based Globalist Research Center, points out that Africa's population has more than tripled during the second half of the 20th century, growing from 230 million to 811 million.
As a result, Africa has become more populous than Europe. Nigeria, Africa's most populous country at 158 million, is expected to grow to 730 million by century's end, making it larger than Europe's projected population of 675 million.
Nigeria is currently the only African country with a population exceeding 100 million.
But 10 other countries in the African continent are expected to join that club before the close of the century: the Democratic Republic of Congo (DRC), Egypt, Ethiopia, Kenya, Malawi, Niger, Sudan, Tanzania, Uganda and Zambia.
Jose Miguel Guzman, chief of the UNFPA's Population and Development Branch, told IPS that globally, the population growth rate is not as high as it has been in the past.
Fertility decline in most countries of the world has contributed to a decline in population growth rates.
"But if we take into consideration least developed countries (LDCs) or most of the sub-Saharan countries, the situation is quite different," Guzman said.
In most of these countries, he said, fertility is still high, and the rate of growth is also high.
In some cases, it is as high as three percent, which implies that the population in these areas will double in about 20 to 25 years.
The date for the eight billion population milestone is projected now to be 2025, he predicted.