Collapsing birth rates mean that the world’s population will fall much faster than expected. We are not prepared for what this means for our societies and our economies. Simon Wilson reports
What’s happening?
Rapidly falling birth rates mean the world’s population will peak, and then start to decline rapidly within decades, according to a new study led by the Institute for Health Metrics and Evaluation (IHME) at the University of Washington. If so, this will be the first time since the Black Death, which killed about 50 million people in the mid-1300s, that the global population will have fallen – and it will mark a radical change from the pattern of global population explosion since the Industrial Revolution. These forecasts are not entirely new. In 2020, a similar large-scale study by the IHME forecast that the number of people in the world would peak at 9.7 billion around 2064 – far earlier than previously expected – and would never be as big as demographers had assumed. What’s new and striking about the latest evidence is the detail of the astonishing collapse in projected fertility rates, and the likely consequences for humanity.
How fast will fertility drop?
Demographers regard a total fertility rate (TFR) of 2.1 children born to each woman as the level needed to sustain the long-term replacement of the population. The IHME study uses cutting-edge methods for forecasting mortality, fertility and key drivers of fertility – principally education levels, unmet need for modern contraception, child mortality and levels of urbanisation. Taken together with live births, TFR rates can be projected for every country in the world in 2050 and 2100, compared with 2021. Global TFR has more than halved over the past 70 years, from about five children per woman to 2.2 in 2021. Already, slightly more than half of countries (110 out of 204) have a TFR below the replacement level of 2.1. By 2050, the global TFR will be about 1.8, and more than three-quarters of countries (155 out of 204) will have TFRs below the crucial level. By 2100, it projects a global TFR of 1.6, and almost all countries (198 out of 204) will no longer be having enough children to maintain their population size.
Are these forecasts reliable?
“One thing we know about demographic projections is that they are nearly always wrong,” says Jeremy Warner in The Telegraph. In the early 1990s, officials predicted the UK population would by
