By 2100, the world’s population will be far older and living more densely packed than today. By then the total number of inhabitants could be in excess of 11 billion – 3.9 billion more than present – and these large increments could have serious environmental, health, political, economic and social implications, experts warn.
The global population first breached the 1 billion mark back in 1820 in the midst of the Industrial Revolution and has been on expansion mode ever since. It took another 123 years before 2 billion was reached. By 1960, it hit 3 billion. Previous projections by the United Nations Population Division expected numbers to plateau in 2100 at 10.9 billion, but new figures released in July (medium variant) suggest there is only a 23% probability that population growth will end this century.
The main driver is higher than anticipated fertility and a slowdown in the pace of fertility declines, particularly in sub-Saharan Africa. According to the projections, Asia is expected to peak at 5.3 billion people in 2050 and slowly fall. In contrast, Africa’s population will almost quadruple from 1.2 billion in 2015 to 4.4 billion by 2100.
In Nigeria, the continent’s most populous country, fertility decline has stalled with women still bearing six children on average. As a result, the population could soar from 182 million to 752 million by 2100, making it the third most populous country in the world after India (1.7 billion) and China (1.0 billion).
India is anticipated to become the largest country in population size, surpassing China around 2022, several years sooner than previously expected. Rounding out the five most populous countries in 2100 will be the United States (450 million) and the Democratic Republic of the Congo (389 million).
An aging world
In contrast, Europe will shrink. Most parts of the Continent are expected to face depopulation by mid-century or sooner. By 2050, Europe is expected to decline from 738 million people to 707 million and slide to 640 million by 2100, though the fall will be more noticeable in Eastern and Southern Europe, than in Western and Northern Europe.
Such a dramatic rise in population may revive the ‘Malthusian nightmare’In 2050, for the first time in history, the number of older people worldwide will be larger than the number of children as declining fertility and falling mortality make those aged over 60 the fastest growing group in the global population. According to the UN figures, the number of persons aged 60 or older is expected to triple to 3.2 billion by 2100, while the oldest old (those 80 years or older) are projected to increase eight-fold to 944 million. Centenarians, those 100 years or older will swell from half a million to 26 million by the start of the next century.
While a remarkable achievement, population aging will require major societal adjustments. For example, according to the World Health Organization, 48 million people worldwide now have dementia, with almost 8 million additional cases recorded each year. Dementia is a major cause of disability and dependency among older people and has significant consequences in terms of direct medical and social costs, as well as the costs of informal care.
In 2010, global costs of dementia were estimated at $604 billion or 1% of global gross domestic product. By 2050, the number of people with dementia is expected to triple to 136 million with much of this increase coming from people in low-and middle-income countries.
Living in the cities
By 2100, most of the human population will be concentrated in cities with virtually all growth occurring in developing countries as rural poor move to cities and become the urban poor. Today, 54% of the world’s population lives in urban areas, a proportion expected to climb to 66% (or an additional 2.5 billion people) by 2050.
In 1950, only two cities in the world had 10 million inhabitants or more (New York and Tokyo), the number defining them as megacities. Today, there are 23 megacities and by 2030, as urban numbers swell, the number of megacities will reach 41.
Throughout history, cities have served as engines of economic growth, vital to a nation’s socio-economic development but the sheer numbers of developing megacities present significant challenges. Governments will need to develop strategies to accommodate future urban growth to reap the benefits of economies of scale, as well as to minimize the environmental and other adverse impacts of urban growth, such as crime, crumbling infrastructure and slums.
But developments may not stop at megacities. For decades, China’s government has tried to limit the size of Beijing, the capital, through draconian residency permits. Recently, it reversed itself and embarked on an ambitious plan to transform Beijing into a new class: a super city of 130 million people.
Projecting future population requires summing up
individual projections for 233 countries and areas. Differing assumptions about future trends in mortality, fertility, immigration and emigration yield various projection variants or scenarios.
This marks the fourth consecutive edition of the biennial report with a medium variant global projection higher than the last. Future population growth is most dependent on the fertility trajectory, of which there is great uncertainty even in the near term.
For example, a scenario in which all countries have fertility that is consistently half a child higher than the medium variant would produce a population of 16.6 billion people by 2100, more than 5 billion higher than the medium-variant projection.
Price of modern life
These population estimates and projections present challenges for all societies, including low labor force participation, especially among youth, limited female empowerment and environmental degradation. Such a dramatic rise in population may revive the “Malthusian nightmare.”
Thomas Malthus, a British economist, famously predicted in 1798 that population growth eventually would outpace food production, resulting in mass starvation. Significantly increasing populations will place pressure on resources such as food and water, while the growth of mega slums in the developing world through rapid urbanization will raise issues from housing to education to health care. In some of the more depressing scenarios, the results of such pressures could contribute to conflict, forced displacement and failing states.
Yet, population growth can be moderated, by more substantial investments in girls’ education, female employment and family planning programs. In the years ahead, governments and the international community will need to address the developmental consequences of population dynamics before they unfold by adopting forward-looking and pro-active policies based on past, current and anticipated demographic trends.