When I Was a Kid, the Earth Only Had 5 Billion People…

On Monday, October 31st, the UN has declared “7 Billion Day“, the day when the world population will reach 7 billion people.  While believing Halloween 2011 is the exact date of the world population crossing the 7 billion threshold is a bit naive, it is interesting to consider the significance of this milestone.  I recall as a child in pre-K celebrating the Day of 5 Billion (July 11, 1987), which got me thinking – has the world population really grown by 40% in my brief lifetime?  And the answer is amazingly – yes.  While it took until from the start of human history til 1804 for humans to reach our first billion, the growth since has been astronomical.  The first doubling after reaching our first billion took 123 years, while the next doubling only took 47 and we’re adding an additional billion people approximately every 13 years.

I’ll be curious to see how world population growth plays out over the course of my lifetime.  If the last 28 years have been any indication, we’re in for a wild ride.

World population milestones (USCB estimates)
Population
(in billions)
1 2 3 4 5 6 7 8 9
Year 1804 1927 1960 1974 1987 1999 2012 2027 2046
Years elapsed 123 33 14 13 12 13 15 19

Source: Wikipedia