what is the problem with human population growth
Human overpopulation Human population has been rising continuously since the end of the Black Death, around the year 1350,[8] although the most significant increase has been since the 1950s, mainly due to medical advancements and increases in agricultural productivity. The rate of population growth has been declining since the 1980s, while the absolute total numbers are increasing. Recent rate increases in several countries previously enjoying steady declines are also apparently contributing to continued growth in total numbers. The United Nations has expressed concerns on continued population growth in sub-Saharan Africa.[9] Recent research has demonstrated that those concerns are well grounded.[10][unreliable source?] As of August 13, 2018 the world's human population is estimated to be 7.643Â billion. [11] Or, 7,622,106,064 on May 14, 2018 and the United States Census Bureau calculates 7,472,985,269 for that same date.[12] and over 7 billion by the United Nations.[13][14][15] Most contemporary estimates for the carrying capacity of the Earth under existing conditions are between 4 billion and 16 billion. Depending on which estimate is used, human overpopulation may or may not have already occurred. Nevertheless, the rapid recent increase in human population is causing some concern. The population is expected to reach between 8 and 10.5 billion between the years 2040[16][17] and 2050.[18] In 2017, the United Nations increased the medium variant projections to 9.8 billion for 2050 and 11.2 billion for 2100.[19]
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 predicted a massive increase to 256 billion by 2150, assuming fertility remains at 1995 levels.[5]