New research has forecast the European Union's population will plummet by millions more than previously predicted.
The United Nations has said the number of people in the bloc will drop to 365 million by 2100, down from 446 million today.
But a new study, published in the medical journal The Lancet, predicts it will fall more sharply, to 308 million by the end of the century.
Scientists, mostly from the Institute for Health Metrics and Evaluation, forecast the fertility rate — the number of children per woman on average — will drop to 1.41 in the EU. Previous UN estimates had put the figure at 1.75.
The new analysis predicts that Earth will be home to 8.8 billion people by 2100, with global growth peaking in 2064 at a population of 9.7 billion. Previous UN projections forecast 10.8 billion.
Why is the fertility rate declining?
Global fertility rates have steadily declined since the 1960s. According to the online publication Our World in Data's study, this can be put down to three factors: "The empowerment of women (increasing access to education and increasing labour market participation), declining child mortality, and a rising cost of bringing up children (to which the decline of child labour contributed)."
The authors of the new study add another reason for the global trend of declining fertility: "Educational attainment and access to contraception."
Women in the EU27 are generally now having fewer children when they are younger, choosing to have them when they are older, which reduces the potential number of children possible on a biological level, according to Eurostat.
By 2100, 21 out of the 27 EU Member States will see their populations decline, the study predicts. Some countries like Bulgaria, Latvia, Portugal, Romania, Slovakia, and Spain will probably even see their populations reduce by more than half by 2100 — up to a 77% decline for Latvia.
The figures show that 15 of the EU's countries, including Italy, Greece, Hungary, Poland and Portugal, are already experiencing a decline.
Five countries (Belgium, Denmark, France, Ireland, and Luxembourg) will gain in population size by 2100, despite a reduction in speed of growth. Scientists attribute these small rises to a relatively steady fertility rate and positive net migration forecast in these countries.
Alongside mortality and migration, fertility is a significant figure for demographers. "Many variables have an effect of this rate," says Catherine Scornet, an Aix-Marseille University lecturer in sociology and demography.
"They can either be direct: the marriage age, the access to birth control methods, the right to abortion" or indirect. "Providing school education to women will also lead them to be fulfilled other than through their role of mothers," she says, and therefore impact the fertility rate.
This too is a worldwide trend. By 2100, 183 countries out of 195 in the study will have a fertility rate lower than the global replacement level (2.1), it predicts. The replacement level is the total fertility rate (the average number of children born per woman) at which a population exactly replaces itself from one generation to the next, without migration.
As many as 23 countries are forecast to have their populations reduced by more than half between 2017 and 2100.
Globally India, Nigeria, China, the U.S. and Pakistan are predicted to have the largest populations in 2100 with 1.09 billion, 791 million, 732 million, 336 million and 248 million inhabitants respectively.
Why do fertility rates matter?
Fertility rates can have a major impact on the political and economical life of the inhabitants of countries, as they determine the number of working-age individuals.
These analyses are extremely important for leaders because they help them assess tomorrow's needs when it comes to infrastructures, job creation, food production and housing among other factors.
The new study has used forecasting of the working-age population to establish a ranking of the top 25 national economies over time.
It predicts that China will rise to the top of this list in 2035 but will be superseded by the U.S. again in 2098, thanks to immigration making up for the country's fertility rate being lower than the replacement level.
A shift in population, and therefore workforce, can cause new domestic policies — an ageing population may mean a country has to reconsider its retirement system, for example.
The study's findings suggest that the ratio of the "population older than 80 years to the population younger than 15 years will increase in countries with more than 25% population decline," adding the "economic and fiscal consequences that will be extremely challenging".
According to Eurostat, people who are 65+ in the European Union represented 16,11% of the population in 2008, which rose to 19.06% in 2018.
"The prospect of seeing a country's population reducing for a leader is not always good news. However, this may be felt as opportune nowadays since the impact on natural resources would be lessened," Scornet notes.
How likely are the predictions to come true?
Researchers chose not to include climate change as a factor in their prospects because of the "challenges" incorporating it represented.
However, they recognised that it "is likely to have a role in future migration patterns, with populations being forced to migrate because of sea-level rise, extreme weather events, environmental degradation, and more."
Factors like global warming will have a major impact on fertility, mortality, and, as we have already seen, migration.
"What is plausible within a generation is far less plausible within an 80-year range of time," Scornet said. However, such studies have the merit of addressing issues that will be essential in the future.
The study concludes by putting forward the many limitations of work on demographics. "Population size and composition are not exogenous factors for countries to account for in their planning, but rather outcomes that they can help direct," researchers said.