IB Geography 3.3.1 Divergent Thinking About Population and Resources Notes

Population Measures Track Different Things and Can Move in Different Directions

1. Absolute population, the growth rate and the total fertility rate are three separate measures, so a claim about one is not a claim about another.
2. The United Nations Population Division's World Population Prospects 2024, the twenty-eighth edition, released on 11 July 2024, estimates world population at 8.2 billion in 2024.
3. The same edition projects a peak of around 10.3 billion in the mid-2080s, a fall to 10.2 billion by 2100, and an 80 percent probability that the peak arrives within this century.
4. It puts the global fertility rate at 2.25 live births per woman, down from 3.31 in 1990, with more than half of all countries and areas already below the replacement level of 2.1.
5. In 63 countries and areas, holding 28 percent of world population in 2024, population had already peaked before 2024.

1. The Population Division's 2021 report Global Population Growth and Sustainable Development, which rests on the 2019 revision of World Population Prospects rather than the 2024 one, records that the growth rate peaked between 1965 and 1970 at an average of 2.1 percent a year.

Malthus Set One Growth Rate Against a Slower One and Concluded the Slower One Binds

Population, when unchecked, increases in a geometrical ratio. Subsistence increases only in an arithmetical ratio.

1. That wording is Thomas Malthus's own, from An Essay on the Principle of Population, printed for J. Johnson in London in 1798.
2. A geometrical series multiplies while an arithmetical series adds, so on his assumptions the gap between the two widens without limit.
3. Preventive checks act on the birth rate through what he called a foresight of the difficulties attending the rearing of a family, principally delayed marriage.
4. A positive check acts on the death rate and is, in his words, the check that represses an increase which is already begun.
5. His subject was subsistence in England during the early decades of industrialization, which is why food is the only ceiling his argument contains.

The Neo-Malthusians Wrote at the Fastest Rate of Population Growth Ever Recorded

1. Neo-Malthusian writing revived the limit argument in the 1960s and 1970s, at the 2.1 percent a year growth peak of 1965 to 1970.
2. It changed Malthus in two ways, by widening the limit from food to resources in general and by making rising consumption a driver alongside rising numbers.

Ehrlich Put a Date on Mass Famine and the Date Passed

The battle to feed all of humanity is over. In the 1970s and 1980s hundreds of millions of people will starve to death in spite of any crash programs embarked upon now.

1. That is the opening of the prologue to the revised edition of Paul Ehrlich's The Population Bomb, first printed in 1971, three years after the 1968 original.
2. No famine on that scale arrived in either of those decades, so the prediction failed on its own terms.
3. FAO's State of Food Security and Nutrition in the World 2026, released on 21 July 2026, estimates that 645 million people, 7.8 percent of world population, faced hunger in 2025.

The Limits to Growth Modelled Scenarios and Was Read as a Forecast

1. The Club of Rome commissioned the study, which an international team at the Massachusetts Institute of Technology began in the summer of 1970.
2. Donella Meadows, Dennis Meadows, Jørgen Randers and William Behrens III published The Limits to Growth in 1972.
3. Their World3 system dynamics model linked five interacting factors, population, agricultural production, natural resources, industrial production and pollution.
4. The book's first conclusion was conditional, that if the present growth trends in world population, industrialization, pollution, food production, and resource depletion continue unchanged, the limits to growth on this planet will be reached sometime within the next 100 years.
5. Its second and third conclusions held that those trends can be altered and that starting sooner improves the chances, so the book offered a choice rather than a schedule.

1. Donella Meadows wrote in her 1992 preface to Beyond the Limits that the book was interpreted by many as a prediction of doom, that it was not a prediction at all, and that it was about a choice.
2. Gaya Herrington's comparison of World3 against observed data, published in the Journal of Industrial Ecology in 2021, found the closest alignment with two scenarios rather than with the standard run.

Planetary Boundaries Quantifies Earth System Limits Without Making Population the Driver

1. Johan Rockström and colleagues proposed the planetary boundaries framework in Nature in 2009, setting quantified boundaries on nine Earth system processes to define a safe operating space.
2. They published the fuller version the same year in Ecology and Society, which is the paper to cite for the boundary values themselves.
3. Richardson and colleagues reported in Science Advances in 2023 that six of the nine boundaries had been transgressed.
4. The Planetary Health Check 2025, published on 24 September 2025 by the Planetary Boundaries Science Lab at the Potsdam Institute for Climate Impact Research, reports seven of nine transgressed, with ocean acidification the seventh.
5. The planetary boundaries framework belongs in the pessimistic strand because it assumes binding physical limits.
6. Its authors present it as an Earth system framework rather than a population model.
7. Its nine boundaries run from climate change and biosphere integrity to freshwater change, ocean acidification and novel entities, so the limits are not agricultural ones.

Boserup Reversed the Causation and Made Population Pressure the Driver of Farming Change

1. Ester Boserup published The Conditions of Agricultural Growth: The Economics of Agrarian Change under Population Pressure with George Allen and Unwin in London in 1965.
2. Her model treats population growth as the independent variable and agricultural change as what follows from it, which is the opposite direction of causation to Malthus.
3. Rising population density raises the cost of leaving land idle, so cultivators shorten the fallow and crop the same ground more often.
4. She classified land use into five systems by fallow length, forest fallow of 20 to 25 years, bush fallow of 6 to 10 years, short fallow of 1 to 2 years, annual cropping with a fallow of a few months, and multi-cropping with none.
5. Shortening the fallow raises output per hectare because the same land carries more harvests in a given run of years.
6. It also raises the labour needed for each unit of output, through weeding, manuring, ploughing, terracing and irrigation, so the productivity of labour falls as the productivity of land rises.
7. Intensification in her account is therefore a response to pressure and not a free gift.

Machakos District Grew Fivefold and Its Land Produced More

1. Mary Tiffen, Michael Mortimore and Francis Gichuki traced Machakos District in Kenya from the 1930s to 1990 and published More People, Less Erosion in 1994.
2. The district's population grew about fivefold, from about 240,000 in 1930 to almost 1,400,000 by 1989.
3. Across the same span the value of output per hectare rose about tenfold, with the value of output per person up about threefold.
4. The authors read this as evidence against the assumption that more people means fewer trees and degraded land.

Simon Won a Ten Year Bet on Metal Prices, and the Decade Chosen Decides the Winner

1. Julian Simon bet Paul Ehrlich in 1980 on the inflation-adjusted prices of five metals, chromium, copper, nickel, tin and tungsten, staking 1,000 dollars as 200 dollars a metal.
2. All five had become cheaper in real terms over the window from September 1980 to September 1990, so Simon won and collected 576 dollars from Ehrlich.
3. Our World in Data's analysis of long-run metal prices since 1900 finds that across different ten year windows Simon and Ehrlich would each have won about half the time.

Intensification Shifts the Cost Onto Water, Labour and Soil

1. India's Central Ground Water Board, under the Ministry of Jal Shakti, published the Dynamic Ground Water Resources Assessment 2025 in December 2025, putting the national stage of groundwater extraction at 60.63 percent.
2. That assessment classes 730 of 6,762 assessment units, 10.8 percent, as over-exploited, meaning annual extraction there exceeds the annual extractable resource.
3. Higher output per hectare can therefore appear in one account as a yield and in another as a falling water table.

Resource Stewardship Treats the Institution as the Variable That Decides the Outcome

1. Resource stewardship holds that what a population does to a resource base is set by the rules under which it uses that base, so an outcome is governed rather than fixed.
2. Like the optimistic position, it treats a resource as a quantity defined by technology, price and law rather than as a fixed physical endowment, which is why reserves can grow while the rock stays the same.
3. Its claim about time is intergenerational, which is why this course uses sustainability in the restricted sense of long-term resource stewardship.
4. Balanced resource stewardship weighs physical limits against adaptation through the rules that govern resource use.
5. Its distinctive claim is that institutions, not arithmetic, carry the explanatory weight.

Hardin's 1968 Argument Describes Open Access, Not Common Property

1. Garrett Hardin published The Tragedy of the Commons in Science in 1968, arguing that each herdsman who adds an animal to a shared pasture takes the whole gain and bears only a share of the cost.
2. Because every user faces the same arithmetic, his conclusion was that ruin follows from rational individual behaviour rather than from malice.
3. The remedies he offered were private property or state regulation, which he summarized as mutual coercion mutually agreed upon.
4. Thirty years later, in Science in 1998, he named the flaw in his own title.

the weightiest mistake in my synthesizing paper was the omission of the modifying adjective 'unmanaged'. In correcting this omission, one can generalize the practical conclusion in this way: A 'managed commons' describes either socialism or the privatism of free enterprise. Either one may work; either one may fail.

Ostrom Documented Commons That Have Lasted Under Their Users' Own Rules

1. Elinor Ostrom published Governing the Commons: The Evolution of Institutions for Collective Action with Cambridge University Press in 1990, drawing on cases of long-enduring user-managed resources.
2. She was awarded the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel in 2009, sharing it with Oliver Williamson for her analysis of economic governance, especially the commons.
3. The prize committee's own summary records that common property is often surprisingly well managed, contrary to the standard theoretical argument against it.
4. Its examples include locally managed irrigation systems in Nepal that have allocated water between users over long periods, and groundwater in parts of California, the subject of her first study.
5. On the Asian grasslands the committee records that Mongolia's traditional seasonal herding left the pasture relatively healthy, while the state collectives imposed in neighbouring China and Russia degraded it heavily.
6. It adds that China's later switch to privatization degraded those pastures further, because settling herders in one place removed the mobility the system depended on.

Northern Cod Collapsed Under Open Access and Was Rebuilt Under Quota

1. Canada closed the northern cod fishery in NAFO divisions 2J3KL off Newfoundland and Labrador under a moratorium in 1992 after the stock collapsed.
2. Fisheries and Oceans Canada announced the return of a commercial fishery on 26 June 2024 with a total allowable catch of 18,000 tonnes, the stock having sat in the cautious zone since 2016.
3. On 12 June 2026 the department announced a 2026 catch of 59,000 tonnes, up 55 percent on the 38,000 tonnes of 2025, and reported the stock in the healthy zone for the first time since the moratorium.
4. The span from the 1992 moratorium to the 2026 healthy-zone assessment is thirty-four years, so a stewardship claim here is a claim about decades.

Stewardship Is a Claim About Rules, Which Makes It Political as Well as Testable

1. Power enters resource stewardship through control over who writes, monitors and enforces the rules.
2. Ostrom's principles assume a bounded group of identifiable users, so they transfer badly to a global commons that has no such group.
3. A low ecological footprint produced by poverty is not stewardship because stewardship is a chosen arrangement rather than a constraint.
4. The circular economy and Sustainable Development Goals put resource stewardship into practice through designed material loops and coordinated targets.

The Three Positions Disagree About Mechanism Before They Disagree About Outcome

1. What sets the limit
   1. Malthus and the neo-Malthusians locate it in a physical ceiling, food for him and resources, pollution and Earth system thresholds for them, Boserup locates it in the labour and investment that intensification costs, and stewardship locates it in the quality of the institutions.
2. What population growth does
   1. For the pessimistic position it is the pressure that breaches the limit, for Boserup it is the pressure that forces the technique to change, and for stewardship it is one variable among several that rules can offset or amplify.
3. What would count as evidence
   1. The pessimistic position points at transgressed boundaries and depleted stocks, the optimistic one at yields, prices and intensified land, and stewardship at paired places whose outcomes diverged under different rules.

Dual-Axis Graphs Separate Population Totals from Growth Rates

1. A line graph with two vertical axes can carry absolute population against the growth rate, which is the pairing that makes population momentum visible.
2. A scenario chart such as the World3 standard run plots conditional futures, so its caption has to say which assumptions produced the curves.
3. Concentration needs a Lorenz curve and its Gini coefficient, since one world total cannot show how unevenly consumption is spread.