Explanation

Rapid increase in population. Rapid growth is called exponential growth. In 1700 AD human population was about 0.6 billion. At the beginning of the twentieth century, it increased to 1.6 billion, and by the end of the century, the human population reached 6.1 billion. This rapid increase in population over a relatively short period is called population explosion. In the 150 years from 1700 AD human population doubled from 0.6 billion to 1.2 billion. In contrast, it increased five time during the next 150 years. In 2011 it was 7 billion