From now until the middle of the 21st century, in only fifty years, the world's population will increase by 50% from 6 billion at the end of 1999 to close to 9 billion in 2050.

October 12, 1999 has been chosen as the official date marking the advent of a planet with 6 billion inhabitants. This historic milestone serves as a reminder that the rate of population growth has varied widely down the centuries. Two thousand years ago, only about 300 million people lived on Earth. The world population grew rather slowly, taking 1,500 years to double. From 1750 onward, however, the rate began to accelerate, doubling to 1.7 billion in a mere 150 years. A decline in the mortality rate, coupled with scientific and technical progress, was responsible for this spectacular growth.

Population growth has continued to accelerate since the turn of the century. In 1950, the world had 2.5 billion inhabitants; on the eve of the third millenium there are 6 billion, with most of the new births occurring in developing countries.

The world's population continues to increase. Nevertheless, we are living at the end of the fastest growth period of human demographics. Between 1995 and 2000, the growth rate was 78 million people per year; less than predicted a few years ago but the equivalent of a new China in 15 years nonetheless.

The growth rate is slowing down. Between 2015 and 2020 the annual growth rate will decrease to 64 million and then to 30 million by 2045-2050. In 2050, the Earth will be inhabited by 8.9 billion humans. A much slower growth rate is predicted after this time even though the possibility remains that the world's population will continue to grow to one day reach 10 billion.

In 2050, Africa and Asia will be home to 20 and 60% of the world's population respectively. Developed nations will have twice as many elderly people as youth and the population of many in between will be in decline.