The global population is expected to hit 7 billion later this year, up from 6 billion in 1999. Between now and 2050, an estimated 2.3 billion more people will be added — nearly as many as inhabited the planet as recently as 1950. New estimates from the Population Division of the Department of Economic and Social Affairs of the United Nations also project that the population will reach 10.1 billion in 2100.
These sizable increases represent an unprecedented global demographic upheaval, according to David Bloom, who is the Clarence James Gamble Professor of Economics and Demography at the Harvard School of Public Health, in a review article published July 29, 2011, in the journal Science.
Over the next 40 years nearly all (97%) of the 2.3 billion projected increase will be in the less developed regions, with nearly half (49%) in Africa. By contrast, the populations of more developed countries will remain flat but will age, with fewer working-age adults to support retirees living on social pensions.
“Although the issues immediately confronting developing countries are different from those facing the rich countries,” Bloom says, “in a globalized world demographic challenges anywhere are demographic challenges everywhere.”
The world’s population has grown slowly for most of human history. It took until 1800 for the population to hit 1 billion. However, in the past half century, population jumped from 3 million to 7 million. This year approximately 135 million people will be born and 57 million will die, a net increase of 78 million people.
Considerable uncertainty about these projections remains, according to Bloom. Depending on whether the number of births per woman continues to decline, the ranges for 2050 vary from 8.1 billion to 10.6 billion, and the 2100 projections vary from 6.2 billion to 15.8 billion.
Population trends indicate a shift in the “demographic center of gravity” from more to less developed regions, Bloom says. Already strained, many developing countries will likely face tremendous difficulties in supplying food, water, housing, and energy to their growing populations, with repercussions for health, security, and economic growth.