The human population of Earth reached 1 billion in 1804, 2 billion in 1927, 3 billion in 1959, 4 billion in 1974 and 5 billion in late 1986. On October 12th 1999, the human population of Earth reached 6 billion. In 2009, we are close to almost 7 billion.
It is really scary when you start to think about this. When will we truly run out of natural resources? When will planet earth run out of food? How many more animals will become endangered due to deforestation?