The conventional projection by the UN is that world population, currently 7.7 billion, will increase to 11.2 billion in 2100, then stabilise before slowly declining. However, current trends cast much doubt on this picture. Fertility rates are in dramatic decline worldwide and world population may peak below nine billion by 2050 and then decline.

In order for a human population to maintain its numbers, each woman must bear, on average, 2.1 children. If the birth rate exceeds 2.1, population numbers increase; if it is less than 2.1, population numbers decline. Birth rates below 2.1 have been common now since 1970. Ireland had a birth rate of 1.92 in 2016 but inward migration is contributing to population growth.

The UN World Fertility Patterns 2015 Report details birth rates (children per woman) for the major world regions – Africa 4.7, Asia 2.2, Europe 1.6, Latin America/Caribbean 2.2, North America 1.9, Oceania 2.4. The overall world fertility rate is 2.5. So world population numbers continue to grow.