On this day ten years ago, the population of the world grew to 6 billion for the first time, according to the estimates of the United Nations Population Fund. Global demography is an inexact science, and there is some controversy regarding population estimates; however it is generally agreed that the world population passed 6 billion some time in mid to late 1999. The world’s population had doubled in just 40 years.
According to the international database figures of the US Census Bureau, the world’s population grew to 3 billion in the second half of 1959, then to 4 billion in the first half of 1974, with one billion people being added in a period of 15 years. The next target of 5 billion was reached in the first half of 1987, so that the fifth billion were added in 13 years. The sixth billion was thus added in a period of 12 years.
If the same progression was followed, we could expect to reach a 7 billion global population 11 years after 1999, that is, in 2010. However, current estimates indicate that global population should reach 6.8 billion in November this year, but will not reach 7 billion until the second half of 2012. Future projections have a high degree of uncertainty, but the best guess is that global population will reach 8 billion in 2026 and 9 billion on 2043 before peaking around 2050 and then starting to decline.