A British report on what it calls a "jaw-dropping" decline in fertility rates around the world are no surprise to Hamilton-based demographer, Dr Natalie Jackson.
Researchers at the University of Washington's Institute for Health Metrics and Evaluation showed the global fertility rate nearly halved to 2.4 in 2017 - and their study, published in The Lancet, projects it will fall below 1.7 by 2100.
As a result, the researchers expect the number of people on Earth to peak at 9.7 billion around 2064, before falling to 8.8 billion by the end of the century.
And 23 nations, including Spain and Japan, are expected to see their populations halve by 2100.
Countries will also age dramatically, with as many people turning 80 as there are being born.
The fertility rate - the average number of children a woman gives birth to - is falling. If the number falls below approximately 2.1, then the size of the population starts to fall.
In 1950, women were having an average of 4.7 children in their lifetime.
Jackson tells Jesse Mulligan about the decline has been predicted for many years and governments have started to take notice, as tax revenue and pensions, for example, depends on a healthy working population.
“World population is growing and will continue to grow until about the end of this century, but the growth rate is slowing because the birth rate per woman is falling and we’ll also got this longevity at old age…As the older population begins to succumb we’ll see higher crude death rates across the world while the death rates keep going down.”
Several European countries are already experiencing a falling birth rate and the news isn’t new, but awareness of it is growing. China’s population is expected to peak at 1.4 billion in 4 years’ time, but by the end of the century it is projected to have only 732 million people.
“We’ve been on an incredible growth phase, that started in 1962 and that population growth rate has been slowing,” she says.
The population boom came down to better science and universal health care arresting child mortality rates. The population fall has little to do with sperm counts, and instead is being driven by more women in education and work, as well as greater access to contraception and the decision to have fewer children.
“The pressure is on young families today to have both partners working. A lot of people desire to have two, three or four children but when they hit one or two the reality of juggling all of that and going to work and coming home at night exhausted and trying to be fresh and bright for your children, it actually makes people think twice about it,” Jackson says.
The inverted age structure of populations – having more old people than young – presents challenges to governments to intervene and make structural changes to the economy.
“When you’ve got a third of the population over the age of 65 – and where I live in Thames-Coromandel we’re already at that - these populations have more demand for the type of resources and services and facilities for older populations and at the same time you haven’t got very many people in the working-age populations.”
Jackson says Government policy must be informed at all levels by these figures and make provision for a change in the way society operates.
“Other countries are doing these already. Many European countries have been looking at population decline and looking at how they’re doing to change rate revenue gathering, taxation, how they’re going to fund health systems.
“Here in New Zealand our birth rate is down 1.73 per woman, so very below the 2.1 you need to replace each generation. We’re only skirting around the edges as to what changes are going to have to be.”