World population estimates from 1800 to 2100, based on UN 2010 projections (red, orange, green) and US Census Bureau historical estimates (black). According to the highest estimate, the world population may rise to 16 billion by 2100; according to the lowest estimate, it may decline to only 6 billion. |
United Nations Department of Economic and Social Affairs Population Division
http://esa.un.org/wpp/unpp/panel_population.htm
U.S. Census Bureau
http://www.census.gov/population/international/
16 billion !!
6 billion !!!!