11B people and counting? Imagine our crowded world in 2100

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Nine countries will account for most of the world’s population growth between now and 2050: India, Nigeria, Pakistan, Democratic Republic of the Congo, Ethiopia, Tanzania, Indonesia, Uganda and the United States.

In the U.S. alone, the population is expected to grow from about 322 million to 450 million by 2100.

India's population is expected to surpass China's in the 2020s.

At the same time, countries with low birth rates will offset that growth.

By 2050, the populations in 11 countries are expected to decrease by more than 15 percent; most of those are in Eastern Europe.

By 2100, Japan — the world's fastest-aging nation — could lose more than a third of its population.

Africa — by contrast — is a young continent. In 19 countries, the average woman has five or more children. (Video via U.N. Women)

This century, Africa's total population is on course to nearly quadruple.

Nigeria, in particular, will see rapid expansion. Currently the world's seventh largest population, it's on track to be the third largest by 2050 and surpass the U.S.

The question for Africa is if its economic growth can keep up with its massive population growth. (Video via U.N. Women)

The related video includes music from Matt Lloyd / CC BY 3.0.  It also contains a handout from U.N. Department of Economic and Social Affairs.)