Global Resource Demand and Population Theories

Why demand depends on more than population size

Resources are the materials and supplies people use to meet their needs. Food, energy and water support everyday life, but they are also needed to produce goods and supply services. Growing demand for these resources increases pressure on the biosphere.

Population growth means more people need food, drinking water and energy. Even if each person consumes the same amount as before, total demand rises. However, population size is only part of the explanation: demand also depends on how much each person consumes and how resources are used in the economy.

How wealth, factories and cities increase demand

Rising affluence means people become wealthier and can afford more goods and services. More households may buy electrical appliances such as washing machines, increasing demand for electricity and water. As countries become richer, consumption of meat and dairy products also tends to rise. Producing these foods uses considerable agricultural land, so changing diets can increase pressure on food-producing environments.

Industrialisation increases manufacturing activity. Factories require energy to operate machinery and water for production processes. In newly emerging economies such as Indonesia and Nigeria, factories manufacture goods both for local customers and for export. Their resource demand therefore reflects consumption beyond their own borders as well as domestic needs.

Urbanisation is an increase in the proportion of people living in towns and cities. Urban populations need food and water brought into cities, while rubbish and other waste must be removed. Transport, refrigeration and these supply systems require energy. Urbanisation can therefore increase resource demand without necessarily increasing the total population.

These processes often reinforce one another. Industrialisation can create better-paid employment, rising incomes allow households to consume more, and expanding urban populations require larger supply systems.

Why regional pressures differ

Population growth and resource consumption are unevenly distributed. Asia has the largest population, so even relatively small changes in consumption per person can have a large effect on total demand. Its rate of population increase has begun to slow, whereas Africa's population is growing rapidly. This creates increasing pressure to expand supplies of food, energy and water.

High-income countries generally use more energy per person. A region does not therefore need rapid population growth to have high resource demand: high consumption per person can maintain substantial pressure on resources. Meanwhile, industrialising economies can experience both population growth and rising consumption.

To assess a regional trend, consider both the number of consumers and their changing consumption. Population growth alone cannot explain every difference between regions.

Reading a range of future population projections

A population projection estimates what might happen under particular assumptions. Different assumptions about future fertility and life expectancy can produce different population paths. A range of projections shows this uncertainty more clearly than a single line.

The graph below demonstrates the method. These are not observed population figures or official forecasts.

Data for Comparing illustrative future population paths

First read the axes: time is on the horizontal axis and global population, in billions, is on the vertical axis. Then follow each line separately. In the lower projection, population rises to 9.2 billion in 2070 and then falls slightly. In the higher projection, it continues rising to 12 billion in 2100.

At 2050, the two values are 9 and 10 billion, a difference of 1 billion. By 2100, they are 9 and 12 billion, a difference of 3 billion. The widening gap shows that the illustrated possible outcomes become more different further into the future; it does not mean that one outcome is certain.

On an actual projection graph, use its key to identify each scenario and the boundary between recorded and projected values. A steeper upward gradient means faster population growth, a flatter line means slower growth, and a downward line means population decline. Higher projected populations imply greater resource demand if consumption per person remains unchanged.

Malthus: population can outgrow food supply

Writing in eighteenth-century England, Thomas Malthus took a pessimistic view of population growth. He argued that population could increase geometrically, multiplying through a sequence such as 1, 2, 4, 8. Food production, he believed, would increase arithmetically, adding a fixed amount through a sequence such as 1, 2, 3, 4.

This difference matters because multiplying eventually produces much faster growth than adding. Malthus believed that population would grow beyond the food supply, producing shortages and checks on population such as famine. He also argued that preventive measures, including later marriage, could slow population growth before such a crisis.

Data for Malthus: food demand grows faster than supply

This constructed graph translates the two sequences into indices, with both starting at 100. The population-demand line represents the food needed by a growing population, assuming unchanged needs per person. The food-supply line represents the amount available. Their shared index allows their relative growth to be compared; it does not equate people with tonnes of food.

At period 1, demand and supply are equal. By period 2, the demand index is 400 while supply is only 300. The widening gap illustrates Malthus's predicted shortage. On a graph of population and likely available resources, check where demand exceeds supply and whether the gap is widening or narrowing.

Boserup: population pressure can stimulate innovation

Writing in the 1960s, Danish economist Ester Boserup offered a more optimistic explanation. She argued that population pressure encourages people to develop farming methods that produce more food: necessity becomes the driver of invention.

Rather than assuming that food supply increases at a fixed rate, Boserup saw agricultural innovation as a response to growing demand. New technology and improved farming methods can increase production. The Green Revolution of the 1960s, including the development of high-yielding crop varieties, provides an example of innovation increasing harvests. Artificial fertilisers are another means of increasing agricultural output.

The key difference is the direction of the relationship. For Malthus, limited food supply restricts population growth. For Boserup, population growth creates pressure to increase food supply. On a Boserup-style graph, food production may rise sharply following innovations rather than following a steadily increasing straight line.

Boserup's explanation challenges Malthus's assumption about slow food-production growth, but it does not make future supply certain. When applying either theory, examine whether resources are actually keeping pace with demand and whether changes in technology or consumption could alter the relationship.

Drivers of resource demand

• Population growth: more consumers need food, energy and water.
• Rising affluence: greater consumption per person; more appliances and more meat and dairy.
• Industrialisation: factories require energy and water, including production for export.
• Urbanisation: supplying cities, refrigerating food and removing waste require energy.

Regional contrasts

• Asia: largest population; population growth is slowing.
• Africa: rapid population growth increases pressure on supplies.
• High-income countries: generally high energy consumption per person.
• Indonesia and Nigeria: industrialisation increases energy and water demand.

Assess both population size and consumption per person.

Population and resources

Malthus: geometric population growth versus arithmetic food-production growth → demand exceeds supply → shortages and population checks. Preventive measures could slow population growth.

Boserup: population pressure → agricultural innovation and intensification → increased food production. High-yielding crop varieties illustrate this response.

Line-graph interpretation

• Check axes, units, key and the start of projections.
• Compare scenarios at the same date; describe the range and how it changes.
• Steeper gradient = faster change; a peak followed by a downward line = decline.
• Where comparable demand exceeds supply, a shortage is indicated.
• Projections depend on assumptions; they are not certain outcomes.