According to UN the world population reached seven billion on 31/10/2011. How correct is UN is a separate issue as there is no round-the-clock monitoring of population all over the world.
Population growth is slowing down and world population is expected to stabilize when it reaches nine billion. However floods, earthquakes, cyclones and other natural calamities play a part. In some countries there has been decline over the years and they want to increase their population. Russia, Australia, France, Germany, Ireland, Japan, South Korea and Singapore want more people.