The world's population three centuries from now will stabilize at 9 billion if fertility levels continue their decline, particularly in the developing world, but could also top more than 1.3 trillion if they remain unchanged from current rates, according to statistics released today by the United Nations.
According to "medium"-level projections, women in every country will each have about two children in the decades to come, raising the world population from its current 6.4 billion to 9 billion in 2300, the UN's Population Division said.
But even small variations in these forecasts will have enormous impacts in the long term. As little as one-quarter of a child under the two-child norm, or one-quarter of a child above the norm, would result in world populations ranging from 2.3 billion to 36.4 billion.
If fertility levels remain unchanged at today's levels, however, world population would rise to 44 billion in 2100, 244 billion persons in 2150 and 1.34 trillion in 2300, according to the Division's new report, World Population to 2300. The UN said this clearly indicates that "current high fertility levels cannot continue over the long term."
Given progress in extending life expectancy, the UN said, people could expect, on average, to live more than 95 years by 2300. Japan, which is the global leader in life expectancy today, is projected to have a life expectancy of more than 106 years by 2300.