World Population To Hit 10 Billion By 2100, Or 15 Billion If....

The world's population of seven billion is set to rise to at least 10 billion by 2100, but could top 15 billion if birth rates are just slightly higher than expected, the United Nations said on Wednesday.

In a report ahead of ceremonies on October 31 to mark the seven billionth human alive today, the UN Population Fund (UNFPA) warned demographic pressure posed mighty challenges for easing poverty and conserving the environment.

"This is a challenge and a call to action. The issue of population is a critical one for all humanity and for planet Earth," Babatunde Osotimehin, the UNFPA's executive director, said at the launch of the report in London.

The world's population of seven billion is set to rise to at least 10 billion by 2100, but could top 15 billion if birth rates are just slightly higher than expected, the United Nations said on October 26, 2011.