when did the world population reached 1 billion
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.[3] 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 2035–2050, with alternative scenarios ranging from a low of 7.4 billion to a high of more than 10.6 billion.[4] 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.[5]
World population estimates Estimates of the "total number of people who have ever lived" is 107.6 billion as of 2011.[11] The answer naturally depends on the definition of "people", i.e. is only Homo sapiens to be counted, or all of genus Homo, but due to the small population sizes in the Lower Paleolithic, the order of magnitude of the estimate is not affected by the choice of cut-off date substantially more than by the uncertainty of estimates throughout the Neolithic to Iron Age.[12] The estimate is more crucially affected by the estimate of infant mortalitys vs. stillborn infants, due to the very high infant mortality throughout the pre-modern period. An estimate on the "total number of people who have ever lived" as of 1995 was calculated by Haub (1995) at "about 105 billion births since the dawn of the human race" with a cut-off date at 50,000 BC (beginning of the Upper Paleolithic), and an inclusion of a high infant mortality rate throughout pre-modern history.[13]
World population World population has experienced continuous growth since the end of the Great Famine of 1315–17 and the Black Death in 1350, when it was near 370 million.[3] The highest population growth rates – global population increases above 1.8% per year – occurred between 1955 and 1975, peaking to 2.06% between 1965 and 1970.[2] The growth rate has declined to 1.18% between 2010 and 2015 and is projected to decline to 0.13% by the year 2100.[2] Total annual births were highest in the late 1980s at about 139 million,[4] and are now expected to remain essentially constant at their 2011 level of 135 million,[5] while deaths number 56 million per year and are expected to increase to 80 million per year by 2040.[6] The median age of the world's population was estimated to be 30.1 years in 2016, with the male median age estimated at 29.4 years and female at 30.9 years.[7]
World population In demographics, the world population is the total number of humans currently living. The world population was estimated to have reached 7.6 billion as of October 2017[1]. The United Nations estimates it will further increase to 11.2 billion by the year 2100.[2]