The world’s population is increasing faster than it has ever done in human history. It took 250,000 years to reach 1 billion, more than a century after that to reach 2 billion (in 1927) and 33 years more to reach 3 billion. By 2050, the world will have over 9 billion people in it and the number will still be rising.
The growth in certain countries has been and will continue to be astounding. Nigeria in 1970 had 57m people. By 2050, unless its fertility rate falls unexpectedly fast, it will have 389m – almost the population of the United States then. Tanzania is growing faster still, from 14m in 1970 to 139m in 2050. By 2100, they will be the third- and fifth-most-populous places on Earth.
Conversely, some national populations that are now among the world’s largest will have hit their peak and be in decline. Russia’s numbers have been falling since 1995. Japan’s peaked at 126m in 2010. China’s will peak at 1.4 billion in 2025, declining thereafter. Even India’s population – the largest in the world in 2050 – is nearer its maximum size than most people realise: its peak, when it reaches 1.7 billion, will occur around 2060, declining thereafter.