You seem to be assuming that lines of growth continue in one direction forever. They do not. In 1900, the population of Sweden was about 5M, and the birth rate

You seem to be assuming that lines of growth continue in one direction forever. They do not. In 1900, the population of Sweden was about 5M, and the birth rate was 4.02 (which was already falling from its historic average of around 5.0). In the 19th century, 20% of the population fled to the US to escape famine. Today, the population is around 10M, and the birth rate is 1.79. Sweden was pretty typical of Europe, pre-WWI. Would you have said "What could go wrong?" when talking about Europe's birth rate and population growth a century ago? No? Then why be afraid of the same pattern in Africa? Population growth today is mostly a function of increased life expectancy and drastically reduced child mortality rates. Low child mortality has led to reduced birth rates everywhere, to the point where most industrialized nations have negative growth (discounting immigration). The birth rate has already leveled off globally. It will level off in Africa, too, and the population will stabilize. A century from now, Africa will have zero population growth.