October 12, 1999. On this date, the world’s human population was estimated to hit 6 billion, according to the United Nations. It took hundreds of thousands of years for Earth’s human population to reach 1 billion in 1804. The 3 billion milestone came in 1960. Not quite 40 years later, global population had doubled to 6 billion. In 2011, global population reached 7 billion mark. Today – October 12, 2015 – it stands at more than 7.3 billion.
Population experts did not agree on the exact date that world population reached the six billion milestone, but they came close. For example, the U.S. Census Bureau set the date just a few months earlier, on July 22, 1999. These numbers are estimates, after all.
And, of course, human population is still growing. Driven by growth in developing countries, population is expected to reach 8.5 billion by 2030. It should reach around 9.7 billion in 2050, with India expected to become the largest country in population size, surpassing China around 2022, while Nigeria could surpass the United States by 2050.
By the year 2100, there should be 11.2 billion humans on the Earth. All of these figures are via a new United Nations report – World Population Prospects: The 2015 Revision – released in July, 2015.
The UNFPA pointed out that the Day of 6 Billion came only 80 days before the year 2000, allowing excellent comparisons to past populations:
In only 40 years, the world population had doubled. In 100 years, it had quadrupled. In only 12 years, it had increased by one billion. Median projections for population growth estimated that by the year 2050, the tally would top 9 billion, with an increase of roughly 77 million people per year.
UNFPA statistics released in September 1999 also stated that the child had a less than 1 in 10 chance of being born into “relative prosperity,” and a 3 in 10 chance of being born into “extreme poverty.”
Bottom line: On October 12, 1999, global human population was estimated to hit 6 billion, according to the United Nations. UNFPA, aka the United Nations Population Fund, marked this date as the Day of 6 Billion.
Deborah Byrd created the EarthSky radio series in 1991 and EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.