ANKARA

The global population hit 8 billion people on Tuesday, a milestone in human development, according to UN estimates.

"The milestone is an occasion to celebrate diversity and advancements while considering humanity's shared responsibility for the planet," UN Secretary-General Antonio Guterres said in a statement.

Though the growth rate has fallen, the world's human population is expected to keep growing, attributed to improvements in public health, nutrition, personal hygiene, and medicine.

"While it took the global population 12 years to grow from 7 to 8 billion, it will take approximately 15 years -- until 2037 -- for it to reach 9 billion, a sign that the overall growth rate of the global population is slowing," the UN said.

India is poised to overtake China as the world's most populous country in 2023, the UN has estimated.

Eight countries, namely the Democratic Republic of Congo, Egypt, Ethiopia, India, Nigeria, Pakistan, the Philippines, and Tanzania, will account for more than half of the predicted increase in world population by 2050.

In 2019, the average life expectancy at birth reached 72.8 years, an increase of about nine years since 1990, while it is anticipated that further reductions in mortality will lead to an average global longevity of around 77.2 years in 2050.