World population milestones
It is estimated that the population of the world reached one billion for the first time in 1804. It would be another 123 years before it reached two billion in 1927, but it took only 33 years to rise by another billion people, reaching three billion in 1960. Thereafter, the global population reached four billion in 1974, five billion in 1987, six billion in 1999 and, by some estimates, seven billion in October 2011 with other estimates being in March 2012. It is projected to reach eight billion by 2024–2030. According to current projections, the world's population is likely to reach around nine billion by 2045–2050, with alternative scenarios ranging from a low of 7.4 billion to a high of more than 10.6 billion. Projected figures vary depending on underlying statistical assumptions and which variables are manipulated in projection calculations, especially the fertility variable. Long-range predictions to 2150 range from a population decline to 3.2 billion in the 'low scenario', to 'high scenarios' of 24.8 billion. One scenario predicts a massive increase to 256 billion by 2150, assuming fertility remains at 1995 levels.
Billionth milestone days 
There is no estimation for the exact day or month the world's population surpassed each of the one and two billion marks. The days of three and four billion were not officially noted, but the International Database of the United States Census Bureau places them in July 1959 and April 1974.
The Day of 5 billion 
The Day of Five billion, 11 July 1987, was designated by the United Nations Population Fund as the approximate day on which world population reached five billion. Matej Gašpar from Zagreb, Croatia (then SR Croatia, SFR Yugoslavia), was chosen as the symbolic 5-billionth concurrently alive person on Earth. The honor went to Zagreb because the 1987 Summer Universiade was taking place in the city at the time.
The Day of 6 billion 
The United Nations Population Fund designated 12 October 1999 as the approximate day on which world population reached six billion. It was officially designated The Day of Six billion. Demographers do not universally accept this date as being exact. In fact there has been subsequent research which places the day of six billion to be nearer to 18 June or 19 June 1999. The International Programs division of the United States Census Bureau estimated that the world population reached six billion on 21 April 1999.
On the Day of Six billion, UN Secretary-General Kofi Annan was in Sarajevo, Bosnia and Herzegovina to monitor the Dayton Agreement. At midnight he went to Koševo Hospital, where Adnan Mević, born at 12.01 am, was named the symbolic 6 billionth concurrently alive person on Earth. He is the first son of Fatima Mević and Jasminko Helać and weighed 3.5 kg.
The Day of 7 billion 
The "Day of Seven Billion" was targeted by the United States Census Bureau to be in March 2012, while the Population Division of the United Nations suggested 31 October 2011, and the latter date has been officially designated by the United Nations Population Fund (UNFPA) as the approximate day on which the world's population reached seven billion people. United Nations Secretary General Ban-Ki Moon is to speak at the United Nations building in New York City on this new milestone in the size of world population and the issues that it will raise, along with promoting the UNFPA's new program named 7 billion Actions, which will seek to: "[build] global awareness around the opportunities and challenges associated with a world of seven billion people" and inspire individuals and organizations to take action.
The Day of 8 billion 
Estimated to be in 2027 (see table)
The Day of 9 billion 
Estimated to be in 2046 (see table)
See also 
- World Population Prospects, the 2010 Revision
- Vaclav Smil, "Global Population: Milestones, Hopes, and Concerns", Medicine & Global Survival, October 1998; Vol. 5, No. 2, 105–108
- "Population seven billion: UN sets out challenges". BBC. 26 October 2011. Retrieved 2011-10-27.
- "Ch. 5: Population Size and Composition". World Population Prospects, the 2000 Revision. Vol.III. United Nations Population Division. p. 171. Retrieved 3 July 2010
- "Executive Summary". World Population Prospects: The 2002 Revision Volume III: Analytical Report. 2002. Retrieved 3 July 2010
- World Population to 2300. New York: United Nations Department of Economic and Social Affairs: Population Division. 2004. pp. 3, 14. Retrieved 3 July 2010
- World Population: 1950–2050. U.S. Census Bureau, Population Division. Update as at June 2010. Retrieved 3 July 2010
- 2009 World Population Data Sheet. Washington, DC: Population Reference Bureau. 2009. Retrieved 3 July 2010
- Key Findings. "Long-Range Population Projections". Proceedings of the United Nations Technical Working Group on Long-Range Population Projections (New York: United Nations: Department of Economic and Social Affairs). 2003. Retrieved 3 July 2010
- Ankica Barbir-Mladinović (19 July 2011). "Petomilijarditi "Zemljanin": Ne slušati stereotipe" (in Croatian). Radio Free Europe. Retrieved 1 October 2011.
- "And Baby Makes Five billion: U.N. Hails a Yugoslav Infant". New York Times. 12 July 1987. Retrieved 1 October 2011.
- Edith M. Lederer (12 October 1999). "World Population Hits 6 billion". The Washington Post. Retrieved 12 October 2010.
- "Population Clock".
- "The Secretary-General, in two-day stopover in Sarajevo, confers with local leaders, United Nations Representative". United Nations. 14 October 1999. pp. SG/T/2204. Retrieved 2 May 2012.
- World UN chief welcomes six billionth baby
- "U.S. Census Bureau – World POPClock Projection". Retrieved 2011-10-27.
- World Population Prospects, the 2008 Revision Frequently Asked Questions Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat, updated 10 November 2010. Retrieved 26 January 2011.
- World Population Prospects, the 2008 Revision Frequently Asked Questions Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat updated 10 November 2010. Retrieved 26 January 2011
- "Day of 7 billion". UNFPA. Retrieved 16 October 2011.
- "About 7 billion Actions". 7 billion Actions. Retrieved 16 October 2011.