DISCOVER YOUR EARTH...

Earth has approximately 6.5 billion human inhabitantsprojections indicate that human population will reach7 billion in 2013 and 9.1 billion in 2050.it is esti-mated that only one eighth of the surface of the earthis suitable for humans to live on-three-quarters iscovered by oceans,and half of the land area is desert,high mountains or other unsuitable terrain.