There are numerous population clocks – http://www.poodwaddle.com/; the world’s population is more than than 7 billion. In 1950 there was roughly 1/3 the population that exists today ~2.5 billion people worldwide.
Some predict that the world population will reach 9 billion by 2050. How do you think that this continued rapid increase in population will affect our environment? How many people do you think our Earth can accommodate?