The Century of Demographic Transition: Population Growth, Ageing and the Reorganization of the World

1. Before the surge: the slow demographic history of humanity

For most of our species' existence, small populations, environmental fluctuations, movement, infectious disease, access to local food and high mortality constrained sustained expansion. No single fertility or death rate characterized all human communities. Foragers, pastoralists and agricultural populations organized reproduction and care differently, and archaeological evidence remains incomplete. Estimates from the distant past depend on settlements, presumed population densities and ecological models; they are not censuses.

Agriculture emerged through multiple processes in different regions beginning roughly twelve millennia ago. Cultivation, domesticated livestock, storage and more permanent settlements increased the food energy obtainable per unit of land in many circumstances. They also made larger settlements and the specialization of labour feasible. Health did not improve uniformly: dense settlements could increase infectious disease, dependence on a small number of crops, and hierarchical control over surplus and land. The movement from mobile to more sedentary subsistence systems created different combinations of security, risk and inequality.

Historical reconstructions brought together by HYDE, Gapminder and Our World in Data indicate that humanity reached about one billion people around 1800 after millennia of relatively slow population growth. That number is approximate: underlying sources and methods change around 1800 and again around 1950. In the nineteenth and twentieth centuries the demographic regime shifted. More people survived to adulthood and old age, increasing total population before family size fell substantially in many societies. This is not a story in which people everywhere simply decided to have many more children. In many countries the death rate declined before the birth rate. [4][5]

Industrialization changed transport, nutrition, sanitation, food supply, public finances and the circulation of knowledge. Vaccination, antibiotics, safe drinking water, obstetric care and epidemic control reduced death risks through different channels and on different national timelines. Colonial exploitation, slavery, war, forced migration and famine were also part of this history. Growth in the global total never meant that the gains from survival and production were shared equally.

2. The demographic arithmetic: births, deaths, migration and momentum

For the planet as a whole, changes in the number of inhabitants result from births minus deaths. For a country, net international migration is added to this balance. A total fertility rate summarizes births per woman under age-specific rates for a particular period. It is not the annual number of births, the crude birth rate per thousand residents or the rate at which a population grows.

The UN estimated 3.31 births per woman in 1990 and approximately 2.25 in 2024. Fertility near 2.1 births per woman is commonly called replacement level in low-mortality societies. That level is not a universal physical constant: survival to reproductive age and the sex ratio at birth affect the actual replacement threshold. A population may keep growing long after fertility falls below replacement because large generations born previously are still entering childbearing years and because people survive for longer. This phenomenon is known as population momentum. [2][3]

The two observations describe a long-run change, not a complete annual time series. Global averages conceal different national realities. Some countries are already below 1.4 births per woman, while others remain at four or more. Infant survival, voluntary access to contraception, education, housing costs, labour conditions and family norms all influence reproductive decisions, but no single explanatory variable can determine the choices made by every household. [2]

Population size is a stock; births, deaths and migration are flows; fertility is a synthetic rate. Confusing them leads to misleading conclusions: fewer births do not immediately mean fewer residents, rising life expectancy cannot by itself determine annual population growth, and migration can increase the population of one country without increasing the world's population.

3. From 1950 to 2100: a curve that changes its meaning

The world had roughly 2.5 billion inhabitants in 1950, 6.2 billion in 2000, and 8.2 billion in 2024. These figures are historical demographic estimates rather than simultaneous headcounts. Approximately 10.3 billion in the mid-2080s and 10.2 billion in 2100 are central projections of the WPP 2024 revision. The absolute number of people can continue increasing while its annual percentage growth slows; a change across two dates must be evaluated relative to the starting population. [1][5][6]

The point for 2085 represents approximately the middle of the decade in which the UN expects a peak, rather than a precise yearly projection. Straight lines connecting rounded anchor points should not be interpreted as an annual linear forecast. The main change from the twentieth-century expectation of unending growth is that sustained low fertility could eventually reverse the global population trend without worldwide catastrophe.

Scenarios are not an inevitable timetable. Armed conflict, epidemics, reproductive change, migration, schooling and environmental disruption can alter future trajectories. The difference between the 2024 revision and earlier projections illustrates this uncertainty. Disagreements among demographic models need not reflect a calculation mistake: they may result from different assumptions about fertility convergence, survival, changing age structures and policy.

4. The survival revolution: living longer reshapes population growth

Longer life expectancy has been among the most consequential economic and social transformations of the modern era. The UN estimated global life expectancy at birth at 73.3 years in 2024, after a partial recovery from the effects of the COVID-19 pandemic, and projected approximately 77.4 years by 2054. Life expectancy at birth summarizes mortality rates during a specified period; it does not mean that everyone born in 2024 will actually live 73.3 years. [1]

UNICEF recorded global under-five mortality of 93.5 per thousand live births in 1990, 76.7 in 2000, 50.6 in 2010 and 37.4 in 2024. The World Health Organization's May 2026 update estimated 4.9 million deaths of children younger than five during 2024. Exceptional progress coexists with severe inequality: the risk of childhood death in poorer regions remains much higher than in affluent countries, while the pace of mortality improvement has slowed over the last decade. [7][8]

Improved survival does more than increase the population count. It changes family decisions. When children become more likely to survive, fewer births may be required to reach a desired number of surviving children. Families may then invest more in each child, provided that income, public services and security allow it. The adjustment differs across places and generations. Continuing preventable deaths, chronic disease and unequal health access show how even the ability to live a long life remains unevenly distributed.

5. Fertility, family and psychology: smaller families do not necessarily mean rejection of parenthood

Reproduction is an intimate decision shaped by economic, biological, social and political conditions. Gary Becker studied how households allocate income and time between the number of children and investment in each child. John Caldwell examined changes in intergenerational wealth flows and obligations. Feminist scholarship and the economics of care have highlighted unequal burdens of gestation, childrearing, lost career time and unpaid domestic work. These frameworks explain pressures and constraints; they do not establish a universal number of children a rational person should have.

The State of World Population 2025 report by UNFPA presented findings from a UNFPA/YouGov survey in 14 countries, collectively accounting for more than one-third of the global population. 39% of surveyed respondents reported that financial constraints had affected or would affect the family size they wanted. Nearly one in five believed they would not have their desired number of children; a similar share mentioned concerns about the future. These are responses in a defined multicountry survey, not a universal census of personal intentions. An inability to realize reproductive preferences can mean having more, fewer or no children against one's wishes. [9]

Housing prices, precarious employment, longer education, limited childcare and unequal domestic responsibilities interact with relationships, personal autonomy and expectations about the future. Climate and political concerns may influence when people choose to have children, but one cannot infer that every delayed birth reflects fear of the future. Social change also includes greater freedom to remain childless, marry later, pursue education and leave undesirable relationships. Reproductive autonomy should not be sacrificed to meet a government's target birth rate.

The WHO estimates that approximately one in six people of reproductive age experience infertility at some point in life. This lifetime prevalence cannot be added mechanically to the UNFPA percentages to produce a total share of people unable to realize reproductive plans. Clinical conditions, treatment costs and social barriers concern different populations and overlapping constraints. [10]

Access to affordable childcare, parental leave, reproductive healthcare, housing and equal career opportunities can remove obstacles to desired family formation. Demographic effects can be modest, delayed or temporary. Cash payments alone do not resolve long working hours, precarious jobs or unequal domestic duties. Conversely, restrictions on contraception, forced sterilization or punishments for remaining childless violate individual rights and can cause severe and lasting social harm.

6. The geography of growth and contraction: demographic weight shifts

The UN's three demographic groups indicate very different future conditions. In countries and areas that had already peaked, including China, Germany, Japan and Russia, the combined population was projected to decline by 14% between 2024 and 2054. Countries expected to peak between 2025 and 2054, including Brazil, would together grow by about 5.3% over the same interval. Across the 126 that would keep growing beyond 2054, aggregate growth would be about 38%. These are changes for groups of countries, not percentages applicable to each individual member. [2]

Sub-Saharan Africa is central to the coming increase in the world's working-age population and the opportunity to turn youth into greater productive capacity. The World Bank projected in a 2025 regional study that the region's economically active population would expand by more than 620 million between 2025 and 2050. This is not a promise that 620 million jobs will automatically be created. Wages, productivity, energy, education, transport, healthcare, investment and security determine whether the demographic opportunity produces rising living standards or instead increases unemployment and insecure work. [11]

China, South Korea, Japan and parts of Europe face a nearly opposite transition: smaller cohorts enter the labour market while the share of elderly residents increases. India still has large working-age generations but substantial regional differences in fertility, education and infrastructure. The United States and Canada combine ageing with migration, which changes age composition without eliminating the worldwide trend toward longer lives. In Gulf economies, international labour migration can powerfully shape the population profile under varying rules of citizenship, employment and residence.

A demographic map is not a ranking of powerful and weak nations. Population size does not automatically translate into productivity, fiscal strength or military capability. A youthful society without adequate employment is not guaranteed rapid growth; an older society can sustain high incomes with education, capital, technology and strong institutions. Age structure creates possibilities and constraints, not predetermined outcomes.

7. The economics of age: education, productivity, consumption and savings

Demographic transition changes the balance between consumers and producers, contributors and beneficiaries, and private investment and public expenditure. David Bloom, David Canning and other researchers developed the concept of a demographic dividend: as fertility falls after years of large child cohorts, the working-age share can temporarily rise. This is a conditional opportunity, not an automatic contribution to gross domestic product.

Economic output can be roughly decomposed into the number of employed people, hours of work, capital per worker and productivity. More people may expand potential labour supply and demand. Yet total GDP is not GDP per person: aggregate output can grow while average living standards stagnate, and improvements in productivity can raise incomes with stable or declining population.

Age composition also changes what households need. Children demand care, nutrition, education and learning infrastructure; younger adults often need housing, mobility, jobs and financing; older populations can increase demand for healthcare, long-term care, accessible transport and asset maintenance. None of these is a fixed consumption basket. Income, public systems, technology and household organization alter both the quantity and cost of service provision.

Education is not merely workforce training. It enables civic participation, reproductive agency, adaptability and individual development. Access divided by class, gender, geography and income determines which populations can benefit from a demographic window.

8. Pensions, public debt and redistribution between generations

Pay-as-you-go pension systems depend on current contributions to finance current benefits. As the number of contributors declines relative to beneficiaries, maintaining the same benefit structure requires some combination of productivity gains, contribution rates, different eligibility rules, tax financing, labour-force participation and benefit adjustments. Funded pensions face demographic risks too: financial assets do not guarantee available real services when care workers, labour and productive capacity are scarce.

The OECD's Pensions at a Glance 2025 projected that the population aged 20–64 would decline by an average of approximately 13% across OECD members by 2064. The aggregate decline was projected to be greater in the European OECD countries. These numbers refer to selected economies and a defined age range; they do not imply identical reductions in every member country. Fiscal consequences arise from the interaction of retirement rules, healthcare, long-term care, tax receipts and productivity. [12]

Ownership of houses and financial assets is shaped by age as well as wealth. Some households accumulate during working years and spend or transfer assets later, but inheritance is highly concentrated and institutions governing property and taxation vary widely. Older populations may exercise considerable electoral influence in systems where participation rates differ by age, without sharing uniform political preferences. The distributive choices concern the costs of services, taxation, asset wealth, previously promised benefits and future risks.

Automation and artificial intelligence add uncertainty rather than resolving the matter mechanically. Higher productivity could partly offset smaller workforces and increase the taxable economic base. It could also concentrate profits, displace tasks and reduce payroll-based financing in systems slow to adapt. Machines cannot be assumed to replace all aspects of care requiring presence, human trust, interpersonal relationships and judgment.

9. Cities, housing and the everyday geography of population

Urban population growth results from births among residents, rural-to-urban movement, changes in administrative boundaries and the reclassification of settlements. The UN's World Urbanization Prospects 2025 adopted a revised spatially comparable approach based on the degree of urbanization and found that 45% of the world's population lived in cities. In this classification cities are distinct from towns and rural areas. The measure is not directly interchangeable with older country-defined percentages of “urban population,” which often include towns. Comparing them without definitions can create a fictitious decline in urbanization. [13]

Density can reduce the per-person costs of transport, water networks, schools and healthcare when infrastructure is planned appropriately. It can also raise land and housing prices where construction lags behind demand. Without investment, rapid growth increases commuting times, pollution, informal settlements and exposure to floods or heat. Housing policy involves location as much as unit counts: access to employment, utilities and transit, land regulation and ongoing maintenance all matter.

Shrinking settlements face the opposite challenge. Schools, roads and water mains remain in place even when population and tax revenues fall. Vacant houses and ageing neighbourhoods create costs that cannot be reduced proportionately with the number of residents. Demographic planning must handle both expansion and contraction, particularly in former industrial districts and small municipalities.

10. Migration: human redistribution and political contest

Migration redistributes people geographically but does not directly change the world's total population. The UN estimated 304 million international migrants in 2024, around 3.7% of humanity. Most people still live in their country of birth. Domestic migration is often more substantial, while refugees, internal displacement, foreign workers and foreign-born residents correspond to different statistical and legal categories. [14][15]

In origin countries, remittances can finance consumption, schooling, housing and businesses, while the departure of nurses, technicians and other skilled workers may worsen shortages. In destinations, migrants can fill vacancies, create firms, pay taxes and increase housing and service demand. Effects on wages and budgets depend on age, skills, legal status, labour-market organization and the economic cycle. It is inaccurate both to claim that all immigration is an effortless economic gain and that every migrant depresses wages.

Migration also becomes politically contested through citizenship, borders, language, national identity and access to public services. Governments may simultaneously need additional workers and face electoral opposition to immigration. Origin countries may value remittances while seeking to retain workers they have educated. Forced displacement caused by war and persecution requires a separate legal and humanitarian framework. Treating it as ordinary voluntary labour migration obscures important distinctions.

11. Brazil: ageing before inequality has been overcome

The 2024 IBGE population projection revision, incorporating newer information and the 2022 census, projected that Brazil would peak at 220,425,299 residents in 2041 before declining to 199,228,708 in 2070. Total fertility fell from 2.32 births per woman in 2000 to 1.57 in 2023. Over the same years, life expectancy rose from 71.1 to 76.4 years, and the share of people aged 60 and above increased from 8.7% to 15.6%. By 2070, the IBGE projected 37.8% in that age group. These numbers belong to Brazil's own 2024 projection revision and should not be blended without qualification with the UN's global model. [16]

Brazil has less time to raise productivity, expand services for older adults, adapt infrastructure and reduce inequality before the consequences of ageing become more pronounced. There is no uniform Brazilian transition. States differ in fertility, life expectancy, internal migration, employment, income and access to public services. A growing logistics and housing centre may need schools and public transport; a shrinking municipality may need to consolidate classrooms and expand geriatric and home-care services.

The consequences reach pension financing, the national health system (SUS), labour markets, housing, credit, supplementary pensions, state transfers, municipal revenues and federal budgets. Longer lives do not mechanically imply identical health spending per person: prevention and healthcare organization influence costs. Nor does lower fertility justify devaluing investment in childhood; smaller cohorts will depend on high-quality education and health to sustain future productivity.

12. Food, land and water: production, access and replenishment

More inhabitants increase demand for food, energy, fertilizer, transport and storage, but hunger is not identical to the world's physical capacity to produce calories. The State of Food Security and Nutrition in the World 2026, prepared by FAO, IFAD, UNICEF, WFP and WHO, estimated that 645 million people experienced hunger in 2025, or roughly 7.8% of the global population. Approximately 2.1 billion experienced moderate or severe food insecurity, and 2.69 billion could not afford a healthy diet. These indicators are not synonyms: they measure chronic undernourishment, lived food insecurity and the affordability of a defined diet, respectively. [17][18]

Household purchasing power, storage and logistics can be as important as the harvest. Weak cold chains can make fruit, vegetables, dairy and protein expensive even when staple grain supplies are adequate. Armed conflict, severe weather, unequal land ownership, post-harvest losses and the cost of credit affect access and prices. Greater agricultural productivity may reduce land conversion per unit produced, yet cheaper output can also increase total consumption and land use unless environmental governance prevents further expansion.

The FAO's SOLAW 2025 reported that more than 60% of human-induced land degradation occurs on agricultural land, including cropland and pasture, while agriculture accounts for more than 70% of global freshwater withdrawals. Withdrawal is not the same as net consumptive use: water can return to the system, sometimes with altered quality. Local scarcity depends on watershed conditions, seasons, infrastructure, pollution and water rights. It cannot be estimated by dividing all the world's water by its population. [19]

In 2024, roughly 2.1 billion people lacked safely managed drinking-water services, according to the WHO–UNICEF joint monitoring programme in its 2025 update; 3.4 billion lacked safely managed sanitation. Access to a safe service depends on investment, maintenance, institutional capacity and inequality, not only on natural water availability. Expanding networks, treatment, reuse and equitable access can improve health even where populations continue to grow. [20]

13. Sustainability: population, consumption, technology and inequality

The IPAT relationship—environmental impact linked to population, affluence and technology—is a heuristic decomposition, not a calibrated universal law. The Kaya identity expresses carbon emissions through population, GDP per person, energy use per unit of GDP and emissions per unit of energy. Both force attention onto material processes: how many people consume what quantity of goods and services, produced using which energy systems, technologies and institutions?

In the IPCC's Sixth Assessment Report, the 10% of households with the highest per-person emissions were estimated to account for 34–45% of global consumption-based household greenhouse-gas emissions, while the lowest-emitting 50% accounted for 13–15%. These are methodological ranges, not point estimates from which an arbitrary midpoint can be declared observed. The additional resource impact of a high-consumption individual is not equivalent to that of someone lacking modern electricity. These inequalities do not imply that population growth is environmentally irrelevant. [21]

A debate focused exclusively on population size can unfairly demand that poor people limit aspirations for health and comfort while affluent groups maintain resource-intensive lifestyles. The opposite assumption, that technology will always eliminate demographic pressures, is also unsupported. Efficiency can lower input use per product and simultaneously lower prices, allowing demand to rise—the rebound effect. Absolute emissions reductions require clean production, electrification, infrastructure, patterns of consumption, enforceable rules and investment.

Sustainability is also a question of time. Fertility, childcare and education affect generations; water networks last for decades; accumulated greenhouse gases remain climatically relevant long after their release. Voluntary lower fertility can moderate future pressures, but cannot replace near-term energy transition and must never be treated as grounds for coercive population policies.

14. Malthus, Boserup, Marx and Sen: the dispute over limits

Thomas Robert Malthus, in the 1798 Essay on the Principle of Population, explored the conflict between population increase and the means of subsistence. The argument emphasized downward pressure on wages and resources if production failed to keep pace with people. Later history demonstrated that treating worldwide famine as the automatic outcome underestimates innovation, transport, voluntarily falling fertility and changes in institutions. None of this abolishes ecological limits in particular landscapes.

Ester Boserup, in The Conditions of Agricultural Growth (1965), emphasized a causal mechanism running in another direction: demographic pressure can encourage agricultural innovation and intensification. Her hypothesis does not imply that every increase in population produces sufficient technology or makes ecological decline impossible. Julian Simon emphasized creativity, specialization and market institutions as sources of adaptation; Paul Ehrlich focused on ecological risks and the scale of human demands. Their disagreement becomes useful when translated into observable conditions rather than the slogans “more people are always beneficial” and “more people are always catastrophic.”

Karl Marx challenged accounts that treat poverty as a natural consequence of the number of poor people while neglecting ownership, wages and relations of production. Amartya Sen demonstrated that severe food crises may arise through loss of people's effective entitlements to food, even when aggregate food availability is not the sole constraint. His capabilities approach separates merely being alive from having practical opportunities to learn, work, participate and exercise freedom. Kate Raworth's framework places a social floor of needs against ecological constraints; it offers a normative orientation, not a single scientific calculation of the Earth's maximum population.

There is no one technical number for the planet's “carrying capacity” that is independent of diets, technology, land use, inequality, acceptable ecological change and the definition of a dignified life. Any absolute figure presented without those conditions conflates a physical estimate with an ethical choice.

15. Politics, state power and reproductive autonomy

Larger populations may expand tax bases, military recruitment pools and domestic markets. Human numbers become state capabilities only through skills, health, infrastructure, coordination and legitimacy. Governments may use demographic narratives to compete over territories, promote immigration rules, finance sectors or pressure family behaviour. Demographic nationalism, eugenics and coercive reproductive interventions have historical records of serious human-rights abuse; imposing births or preventing births is no substitute for social policy.

Gender inequality links demography to politics directly. Women may shoulder a disproportionate share of caregiving, face discrimination because of pregnancy, or lack adequate access to contraception and medical care. Campaigns urging more births while ignoring unpaid labour and unequal costs may increase social pressure without permanently changing family decisions. Conversely, denying education and family planning can prevent individuals from freely choosing smaller families. The objective of public policy should be genuine informed choice, not compliance with a numerical population target.

Demographic borders do not correspond neatly to boundaries of power. A young region may supply labour and consumers to the world while remaining dependent on imported technology, credit, fertilizers and capital goods. An ageing society may retain high productivity, advanced manufacturing and financial capacity. Geopolitical influence depends on the interaction between population, knowledge, institutions, productive capability and control over strategic resources.

16. Three possible futures, without inevitable destiny

Productive adaptation. Ageing societies increase labour participation, productivity, preventive healthcare and efficiency in long-term care. Younger societies invest in schooling, infrastructure and formal employment. Cleaner energy and improved agriculture reduce resource use per unit produced. This pathway would weaken if productivity failed to offset care costs or the gains remained concentrated in narrow regions.

Demographic dualism. Older economies compete for skilled workers and capital while young societies struggle to create enough jobs and infrastructure. Migrants encounter barriers and remittances offset only some costs in origin communities. Technology increases aggregate production but amplifies inequality without redistribution or wider access. This pathway becomes less plausible if job quality, wages and essential services converge rapidly.

Environmental stress with weak institutional response. Extreme weather, soil degradation and high food costs hurt vulnerable populations. Limited fiscal capacity prevents adaptation regardless of national population size. If water systems, logistics, energy and social protection improve faster than climate pressures intensify, this scenario becomes less plausible. It cannot be treated as an inevitable forecast of collapse.

Demographic change is not a binary struggle between “too many people” and “too few babies.” The reduction of mortality transformed humanity's chances of survival; voluntary fertility decline changed families; inequality continues to determine who benefits. For decades, expansion will be especially consequential where schools, employment and infrastructure remain insufficient. Elsewhere, the essential task will be adapting production, wealth and public institutions to longer lives and fewer births. Sustainable outcomes depend less on one magical global headcount than on the organization of labour, consumption, energy, distribution and individual rights.

References

[1] United Nations, World Population Prospects 2024: https://population.un.org/wpp.

[2] UN DESA, Policy Brief 167 — Leveraging population trends for a more sustainable and inclusive future: https://desapublications.un.org/policy-briefs/un-desa-policy-brief-no-167-leveraging-population-trends-more-sustainable-and.

[3] UN DESA, World Population Prospects 2024: Summary of Results: https://desapublications.un.org/publications/world-population-prospects-2024-summary-results.

[4] Our World in Data, Population Growth: https://ourworldindata.org/population-growth.

[5] Our World in Data, Population, 10,000 BCE to 2023 — data sources and methods: https://ourworldindata.org/grapher/population.

[6] WHO/UNICEF, Progress on household drinking-water, sanitation and hygiene 2000–2024 (contextual population series): https://www.who.int/publications/i/item/9789240115149.

[7] UNICEF, Under-five mortality — dataset: https://data.unicef.org/country/world/.

[8] WHO, Child mortality under 5 years (2026): https://www.who.int/news-room/fact-sheets/detail/child-mortality-under-5-years.

[9] UNFPA, State of World Population 2025: The real fertility crisis: https://www.unfpa.org/swp2025.

[10] WHO, Infertility: https://www.who.int/news-room/fact-sheets/detail/infertility.

[11] World Bank, Africa’s Pulse: https://www.worldbank.org/en/publication/africa-pulse.

[12] OECD, Pensions at a Glance 2025 — demographic old-age to working-age ratio: https://www.oecd.org/en/publications/2025/11/pensions-at-a-glance-2025_76510fe4/full-report/demographic-old-age-to-working-age-ratio_25476b96.html.

[13] UN DESA, World Urbanization Prospects 2025: https://www.un.org/development/desa/pd/content/world-urbanization-prospects-2025-summary-results.

[14] UN DESA, International Migrant Stock 2024: https://www.un.org/development/desa/pd/content/international-migrant-stock.

[15] IOM, World Migration Report 2026: https://publications.iom.int/books/world-migration-report-2026-chapter-2.

[16] IBGE, Brazil and federative-unit population projections: 2024 revision: https://www.ibge.gov.br/estatisticas/sociais/populacao/9109-proje%C3%A7%C3%A3o-da-populacao.html.

[17] FAO/IFAD/UNICEF/WFP/WHO, State of Food Security and Nutrition in the World 2026: https://www.fao.org/publications/fao-flagship-publications/the-state-of-food-security-and-nutrition-in-the-world.

[18] UNICEF, SOFI 2026 — food security indicators: https://data.unicef.org/resources/sofi-2026/.

[19] FAO, The State of the World's Land and Water Resources for Food and Agriculture 2025: https://www.fao.org/publications/fao-flagship-publications/the-state-of-the-worlds-land-and-water-resources-for-food-and-agriculture/.

[20] WHO/UNICEF, JMP 2025: Progress on drinking water, sanitation and hygiene: https://data.unicef.org/resources/jmp-report-2025/.

[21] IPCC, Sixth Assessment Report, Working Group III, Summary for Policymakers: https://www.ipcc.ch/report/ar6/wg3/chapter/summary-for-policymakers/.

Theoretical and historical bibliography: Thomas Malthus, An Essay on the Principle of Population (1798); Karl Marx, Capital (1867); Ester Boserup, The Conditions of Agricultural Growth (1965); Julian Simon, The Ultimate Resource (1981); Paul Ehrlich, The Population Bomb (1968); Amartya Sen, Poverty and Famines (1981) and Development as Freedom (1999); Gary Becker, A Treatise on the Family (1981); John Caldwell, Theory of Fertility Decline (1982); David Bloom and David Canning, research on demographic dividends; Ronald Lee and Andrew Mason, research on generational economics; Hans Rosling, Factfulness (2018); Kate Raworth, Doughnut Economics (2017). Conceptual arguments are not substitutes for current demographic observations.