SEATTLE, July 14, 2020 /PRNewswire/ -- Improvements in
access to modern contraception and the education of girls and women
are generating widespread, sustained declines in fertility, and
world population will likely peak in 2064 at around 9.7 billion,
and then decline to about 8.8 billion by 2100—about 2 billion lower
than some previous estimates [1], according to a new study
published in The Lancet.
The modelling research uses data from the Global Burden of
Disease Study 2017 to project future global, regional, and national
population. Using novel methods for forecasting mortality,
fertility, and migration, the researchers from the Institute for
Health Metrics and Evaluation (IHME) at the University of Washington's School of Medicine
estimate that by 2100, 183 of 195 countries will have total
fertility rates (TFR), which represent the average number of
children a woman delivers over her lifetime, below replacement
level of 2.1 births per woman. This means that in these countries
populations will decline unless low fertility is compensated by
immigration.
The new population forecasts contrast to projections of
'continuing global growth' by the United Nations Population
Division [1], and highlight the huge challenges to economic growth
of a shrinking workforce, the high burden on health and social
support systems of an ageing population, and the impact on global
power linked to shifts in world population.
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, compared with 1.7 billion under 20 years,
underscoring the need for liberal immigration policies in countries
with significantly declining working age populations.
"Continued global population growth through the century is no
longer the most likely trajectory for the world's population", says
IHME Director Dr. Christopher
Murray, who led the research. "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." [2]
IHME Professor Stein Emil Vollset, first author of the paper,
continues, "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."
[2]
Dr Richard Horton,
Editor-in-Chief, The Lancet, adds: "This important
research charts a future we need to be planning for urgently. It
offers a vision for radical shifts in geopolitical power,
challenges myths about immigration, and underlines the importance
of protecting and strengthening the sexual and reproductive rights
of women. The 21st century will see a revolution in the story of
our human civilisation. Africa and
the Arab World will shape our future, while Europe and Asia will recede in their influence. By the
end of the century, the world will be multipolar, with India, Nigeria, China, and the US the dominant powers. This
will truly be a new world, one we should be preparing for today."
[2]
Accelerating decline in fertility worldwide
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.
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 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 course of 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).
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; see table).
"This study is a thought-provoking contribution to the very
lively, ongoing debate around the world's demographic trajectory
and its impact on our common future", said Dr. Natalia Kanem,
Executive Director of the United Nations Population Fund. "While
the models, projections and time frames of different institutions
may vary, all signs point towards declining global fertility.
Protecting the reproductive rights and choices of women will be
crucial in this demographic transition."
Huge shifts in global age structure – with over 80s outnumbering
under 5s two to one
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, whilst 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%.
Furthermore, the global ratio of non-working adults to workers
was around 0.8 in 2017, but is projected to increase to 1.16 in
2100 if labour force participation by age and sex does not
change.
"While population decline is potentially good news for reducing
carbon emissions and stress on food systems, with more old people
and fewer young people, economic challenges will arise as societies
struggle to grow with fewer workers and taxpayers, and countries'
abilities to generate the wealth needed to fund social support and
health care for the elderly are reduced", says Vollset. [2]
Declining working-age populations could see major shifts in
size of economies
The study also examined the economic impact of fewer working-age
adults for all countries in 2017. While China is set to replace the USA 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 USA is expected to reclaim the top spot by
2098, if immigration continues to sustain the US workforce (figure
9).
Although numbers of working-age adults in India are 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 power in Asia to protect its working-age population
over the century. It is expected to surpass China's workforce population in the mid-2020s
(where numbers of workers are estimated to decline from 950 million
in 2017 to 357 million in 2100)—rising up the GDP rankings from 7th
to 3rd (figure 8).
Sub-Saharan Africa is likely to become an increasingly powerful
continent on the geopolitical stage as its population rises.
Nigeria is projected to be the
only country among the world's 10 most populated nations to see its
working-age population grow over the course of the century (from 86
million in 2017 to 458 million in 2100), supporting rapid economic
growth and its rise in GDP rankings from 23rd place in 2017 to 9th
place in 2100 (figure 8).
While the UK, Germany, and
France are expected to remain in
the top 10 for largest GDP worldwide at the turn of the century,
Italy (from rank 9th in 2017 to
25th in 2100) and Spain (from 13th
to 28th) are projected to fall down the rankings, reflecting much
greater population decline (figure 9).
Liberal immigration could help sustain population size and
economic growth
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 USA, Australia, and Canada, will probably maintain their
working-age populations through net immigration (see appendix 2
section 4). Although the authors note that there is considerable
uncertainty about these future trends.
"For high-income countries with below-replacement fertility
rates, the best solutions for sustaining current population levels,
economic growth, and geopolitical security are open immigration
policies and social policies supportive of families having their
desired number of children", Murray says. "However, 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." [2]
The authors note some important limitations, including that
while the study uses the best available data, predictions are
constrained by the quantity and quality of past data. They also
note that past trends are not always predictive of what will happen
in the future, and that some factors not included in the model
could change the pace of fertility, mortality, or migration. For
example, the COVID-19 pandemic has affected local and national
health systems throughout the world, and caused over half a million
deaths. However, the authors believe the excess deaths caused by
the pandemic are unlikely to significantly alter longer term
forecasting trends of global population.
Writing in a linked Comment, Professor Ibrahim Abubakar, University College London
(UCL), UK, and Chair of Lancet Migration (who was not involved in
the study) [3], says: "Migration can be a potential solution to the
predicted shortage of working-age populations. While demographers
continue to debate the long-term implications of migration as a
remedy for declining TFR, for it to be successful, we need a
fundamental rethink of global politics. Greater multilateralism and
a new global leadership should enable both migrant sending and
migrant-receiving countries to benefit, while protecting the rights
of individuals. Nations would need to cooperate at levels that have
eluded us to date to strategically support and fund the development
of excess skilled human capital in countries that are a source of
migrants. An equitable change in global migration policy will need
the voice of rich and poor countries. The projected changes in the
sizes of national economies and the consequent change in military
power might force these discussions."
He adds: "Ultimately, if Murray and colleagues' predictions are
even half accurate, migration will become a necessity for all
nations and not an option. The positive impacts of migration on
health and economies are known globally. The choice that we face is
whether we improve health and wealth by allowing planned population
movement or if we end up with an underclass of imported labour and
unstable societies. The Anthropocene has created many challenges
such as climate change and greater global migration. The
distribution of working-age populations will be crucial to whether
humanity prospers or withers."
View original content to download
multimedia:http://www.prnewswire.com/news-releases/ihme-world-population-likely-to-shrink-after-mid-century-forecasting-major-shifts-in-global-population-and-economic-power-301093565.html
SOURCE Institute for Health Metrics and Evaluation