Global population could top 12 billion by 2100
Contrary to some earlier projections, the world's聽population聽will soar through the end of the 21st century thanks largely to聽sub-Saharan Africa's higher-than-expected birth rates,聽United Nations聽and other聽population聽experts said on Thursday.
There is an 80 percent likelihood that the number of people on the planet, currently 7.2 billion, will increase to between 9.6 billion and 12.3 billion by 2100, the researchers said. They also saw an 80 percent probability that聽Africa's聽population聽will rise to between 3.5 billion and 5.1 billion by 2100 from about 1 billion today.
The study, led by U.N. demographer聽Patrick Gerland聽and聽University of Washington聽statistician and sociologist Adrian Raftery and published in the journal Science, foresees only a 30 percent chance that earth's聽population聽will stop rising this century.
"Previous forecasts did indeed forecast a leveling off of the world聽population聽around 2050, and in some cases a decline," Raftery said.
Raftery said the new projections arise from data that clearly establishes that birth rates in聽sub-Saharan Africa聽have not been decreasing as quickly as some experts had expected, a trend that was "not as clear when previous forecasts were made."
Raftery said the researchers used data on聽population, fertility, mortality and migration from every country and then predicted future rates using new statistical models. Some of the figures, such as the median projection of the聽population聽hitting 10.9 billion by 2100, mirror a U.N. report published in 2013.
U.N. demographer Gerland said聽sub-Saharan Africa聽countries already with big populations and high fertility levels are expected to drive聽population聽growth, including聽Nigeria,聽Tanzania, Democratic聽Republic of the Congo,聽Niger,聽Uganda,聽Ethiopia,聽Kenya,聽Zambia,聽Mozambique聽and聽Mali.
The world's聽population聽reached 1 billion in the early 19th century, doubled to 2 billion in the 1920s and doubled again to 6 billion in the 1990s. It hit 7 billion in 2011.
The findings underscore worries expressed for decades by some experts about a planet growing more crowded and humankind exhausting natural resources, struggling to produce enough food or cope with poverty and infectious diseases.
Raftery said African nations could benefit by intensifying policies to lower fertility rates, with studies showing that greater access to contraceptives and more education for girls and women can be effective.
The researchers projected that聽Asia's聽population, now 4.4 billion, will peak at around 5 billion people in 2050, then begin to decline. They forecast that the populations of North America,聽Europe聽and聽Latin America聽will stay below 1 billion each by 2100.
Among the experts who had predicted the global聽population聽rise would peter out was a 2010 report by Austrian demographer聽Wolfgang Lutz. He forecast it likely would reach 8 billion to 10 billion by 2050 but "population聽stabilization and the onset of a decline are likely" in the second half of the century.聽
