According to the article, "Both groups [the United Nations and the IIASA] foresee India becoming the world's most populous country, with its numbers peaking around 2070 and declining to around 1.5 or 1.6 billion by 2100. Where they differ most is in their estimates of the coming population decline in China and of the coming population explosion in Africa south of the Sahara—where most of the world's growth is going to occur.” Explain the population explosion in sub-Saharan Africa. Why is most of the growth projected to be in this region and not in India or China? Be sure to use vocabulary terms (natural increase rate, fertility rate, doubling time) in your response.
Why do the two groups, the United Nations and the IIASA, differ on their projections for the growth of the world’s population, and how much uncertainty exists?