Global population will shrink after 2050 and only liberal immigration laws can save US economy, says study

The new study also predicts huge shifts in the global age structure, with an estimated 2.37 billion individuals over 65 years globally in 2100


                            Global population will shrink after 2050 and only liberal immigration laws can save US economy, says study
(Getty Images)
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The global population is likely to shrink after the mid-century and this will bring major shifts in the world’s economic power centers. By 2100, projected fertility rates — which represent the average number of children a woman delivers over her lifetime — in 183 countries will not be high enough to maintain current populations without liberal immigration policies, according to a new analysis that forecasts global, regional, and national populations, mortality, fertility, and migration for 195 nations. Policy options to adapt to continued low fertility, while sustaining and enhancing female reproductive health, will be crucial in the years to come, say researchers from the Institute for Health Metrics and Evaluation (IHME) at the University of Washington's School of Medicine.

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Improvements in access to modern contraception and the education of girls and women are generating widespread, sustained declines in fertility, and the global population is forecasted to peak in 2064 at around 9.7 billion people and fall to 8.8 billion by century's end, about 2 billion lower than some previous estimates, write authors in the study published in The Lancet. An estimated 23 countries will see populations shrink by over 50% by century's end. The US is projected to have population growth until just after mid-century (364 million in 2062), followed by a moderate decline of less than 10% to 336 million by 2100 — the world's fourth most populous country.

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The researchers also predict that while the US had the largest economy in 2017, China is set to replace it in 2035. However, the US is forecasted to once again become the largest economy in 2098 — bolstered by immigration. Among the 10 countries with the largest populations in 2017 or 2100, the US is predicted to have the fifth-highest life expectancy in 2100 (82.3 years), up from 78.4 in 2017.

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“Continued global population growth through the century is no longer the most likely trajectory for the world's population. This study provides governments of all countries an opportunity to start rethinking their policies on migration, workforces, and economic development to address the challenges presented by demographic change,” says IHME Director Dr Christopher Murray, who led the study.

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Top ten countries by population in 2017 and 2100 (The Lancet)

Faster decline in fertility worldwide

The modeling research looked at data from the Global Burden of Disease Study 2017 to make their projections. By 2050, 151 countries are forecasted to have a total fertility rate lower than the replacement level of 2.1 births per woman, and 183 are forecasted to have a TFR below the replacement level by 2100. This means that in these countries populations will decline unless low fertility is compensated by immigration. In the US, for example, the total fertility rate is predicted to steadily decrease from 1.8 in 2017 to 1.5 in 2100, well below the minimum birth rate considered necessary to maintain existing population levels long-term without immigration.

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“The global TFR is predicted to steadily decline, from 2.37 in 2017 to 1.66 in 2100 — well below the minimum rate (2.1) considered necessary to maintain population numbers (replacement level), with rates falling to around 1.2 in Italy and Spain, and as low as 1.17 in Poland. Even slight changes in TFR translate into large differences in population size in countries below the replacement level. Increasing TFR by as little as 0.1 births per woman is equivalent to around 500 million more individuals on the planet in 2100,” says the study.

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Much of the anticipated fertility decline is predicted in high-fertility countries, particularly those in sub-Saharan Africa where rates are expected to fall below the replacement level for the first time — from an average of 4.6 births per woman in 2017 to just 1.7 by 2100. In Niger, where the fertility rate was the highest in the world in 2017 — with women giving birth to an average of seven children — the rate is projected to decline to around 1.8 by 2100. “Nevertheless, the population of sub-Saharan Africa is forecast to triple over the century, from an estimated 1.03 billion in 2017 to 3.07 billion in 2100 — as death rates decline and an increasing number of women enter reproductive age. North Africa and the Middle East is the only other region predicted to have a larger population in 2100 (978 million) than in 2017 (600 million),” the findings suggest.

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Many of the fastest-shrinking populations will be in Asia and central and eastern Europe. Populations are expected to more than halve in 23 countries and territories, including Japan (from around 128 million people in 2017 to 60 million in 2100), Thailand (71 to 35 million), Spain (46 to 23 million), Italy (61 to 31 million), Portugal (11 to 5 million), and South Korea (53 to 27 million). An additional 34 countries are expected to have population declines of 25 to 50%, including China (1.4 billion in 2017 to 732 million in 2100).

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“A very real danger exists that, in the face of declining population, some countries might consider policies that restrict access to reproductive health services, with potentially devastating consequences. It is imperative that women's freedom and rights are at the top of every government's development agenda,” says Dr Murray.

Huge shifts in global age structure

As fertility falls and life expectancy increases worldwide, the number of children under 5 years old is forecasted to decline by 41% from 681 million in 2017 to 401 million in 2100, while the number of individuals older than 80 years is projected to increase six-fold, from 141 million to 866 million. Similarly, the global ratio of adults over 80 years to each person aged 15 years or younger is projected to rise from 0.16 in 2017 to 1.50 in 2100, in countries with a population decline of more than 25%.

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According to the team, the new population forecasts highlight the huge challenges to the economic growth of a shrinking workforce, the high burden on health and social support systems of an aging population, and the impact on global power linked to shifts in the world population. “Huge shifts are predicted in the global age structure, with an estimated 2.37 billion individuals over 65 years globally in 2100, compared with 1.7 billion under 20 years,” they add.  

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Declining working-age populations

Dramatic declines in working age-populations are forecasted in countries such as India and China, which will hamper economic growth and lead to shifts in global powers. The study also suggests that population decline could be offset by immigration, with countries that promote liberal immigration better able to maintain their population size and support economic growth, even in the face of declining fertility rates. The model predicts that some countries with fertility lower than replacement level, such as the US, Australia, and Canada, will probably maintain their working-age populations through net immigration, but cautioned that there is considerable uncertainty about these future trends.

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(Getty Images)

In 2100, the US is forecasted to have the fourth largest working-age population in the world (around 181 million), after India, Nigeria, and China — with immigration likely sustaining the US workforce, “with the largest net immigration in absolute numbers.” However, the US liberal immigration policies have faced a political backlash in recent years, threatening the country's potential to sustain population and economic growth, says the study. “While China is set to replace the US in 2035 with the largest total gross domestic product (GDP) globally, rapid population decline from 2050 onward will curtail economic growth. As a result, the US is expected to reclaim the top spot by 2098, if immigration continues to sustain the US workforce,” write authors.

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While the number of working-age adults in India is projected to fall from 762 million in 2017 to around 578 million in 2100, it is expected to be one of the few, if only, major powers in Asia to protect its working-age population over the century, shows analysis. The UK, Germany, and France are expected to remain in the top 10 for largest GDP worldwide at the turn of the century, but Italy (from rank 9 in 2017 to 25 in 2100) and Spain (from 13 to 28) are projected to fall down the rankings, reflecting much greater population decline. 

“The societal, economic, and geopolitical power implications of our predictions are substantial. In particular, our findings suggest that the decline in the numbers of working-age adults alone will reduce GDP growth rates that could result in major shifts in global economic power by the century's end. Responding to population decline is likely to become an overriding policy concern in many nations, but must not compromise efforts to enhance women's reproductive health or progress on women's rights,” says Stein Emil Vollset, first author and IHME Professor.

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