Human population affects demand for land, water, food, energy, housing, transport and waste services. Population change does not automatically create the same environmental outcome everywhere. Age structure, income, consumption, settlement pattern, infrastructure and government choices all affect the result.
These notes follow sections 7.1 to 7.3 of Cambridge IGCSE Environmental Management 0680 for examinations in 2027, 2028 and 2029.
7.1 Population density, distribution and structure
Population distribution describes how people are spread across an area. Population density measures how many people live in a given area, usually in people per square kilometre:
population density=land area in km2population
A sparsely populated place contains relatively few people, while a densely populated place contains many. Density is an average, so it can hide local clusters. A country with a low national density may still contain a very crowded capital city and vast almost-empty regions.
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Attempt the matching topic bank before reopening the notes. Use each missed idea to decide what to review next.
Physical and human conditions influence distribution. Water supply, relief, soils, climate and hazard risk affect where settlement is practical. Employment, transport, services, political stability and historical development also attract or discourage settlement. In an examination answer, use evidence from the supplied map or table rather than assuming that every coast or river is densely populated.
A population pyramid shows the numbers or percentages of females and males in age groups. Read the axes and scale first. A broad base indicates a large young population, while the width of older age bars provides evidence about survival into old age. The syllabus groups the population into young dependants, the working population and elderly dependants. Dependency is an age-based classification here, not a claim that every working-age person has a job or that every older person is economically inactive.
Compare pyramids by referring to specific features:
A wide base suggests a large proportion of children and potentially high demand for schools, vaccinations and future employment.
A narrow base suggests fewer recent births relative to other age groups.
A relatively wide top suggests a larger elderly population and possible demand for healthcare, pensions and accessible services.
Bulges or indentations may reflect past changes in births, deaths or migration, but a cause should be inferred only when supporting information is available.
Cambridge limits economic group terminology here to the World Bank categories low-income country (LIC), middle-income country (MIC) and high-income country (HIC). An LIC and HIC may show contrasting population structures, but the label does not determine one compulsory pyramid shape. Use the data shown. A comparison needs paired statements, such as “Country A has a wider 0 to 4 bar than Country B, whereas Country B has a greater proportion aged 70 and above.”
7.2 Changes in population size
Population size changes through births, deaths and migration. The syllabus represents birth rate through children per woman and death conditions through life expectancy. Higher life expectancy generally means people survive longer, but it does not directly state the number of deaths in one year.
Immigration is movement into a place and emigration is movement out. A factor that encourages people to leave is a push factor, such as conflict, unemployment, drought or poor access to services. A pull factor, such as safety, employment, education or healthcare, attracts people to a destination. The same factor can operate differently for different people, and migration may be temporary or permanent.
Rural-to-urban migration is one process contributing to urbanisation, the increasing proportion of people living in urban areas. These terms are related but not identical. Urbanisation can also result from natural increase within towns or the reclassification and expansion of settlements.
Rapid population growth can increase demand for housing faster than formal construction, contributing to informal urban settlements. Large urban populations can support megacities, employment and specialised services, but they also place pressure on resources, energy, sanitation, water, waste systems, land, facilities and infrastructure.
Environmental and social effects can include:
air pollution from vehicles, industry or fuel use;
land and water pollution where waste and wastewater are not safely managed;
light, noise and visual pollution in dense settlements;
traffic congestion, longer journeys and higher fuel consumption;
pressure on land for housing, food production, industry or habitats;
changing employment opportunities, including both new markets and unemployment or insecure work.
Avoid a one-direction argument. A dense population can make public transport, piped water and waste collection more efficient per person when investment and governance are strong. A smaller but high-consuming population can use more energy and materials than a larger low-consuming population. The environmental outcome therefore depends on population, consumption and management together.
7.3 Managing population size
Population strategies influence births, health and migration, but they also raise questions about choice, equality and long-term effects.
Access to contraception helps people decide the number and spacing of children. Its effectiveness depends on affordability, reliable supply, information and social acceptance.
Anti-natalist policies aim to reduce births. Incentives, information and access to services may change behaviour, but coercive approaches can violate rights and create an ageing population or future labour shortage.
Pro-natalist policies encourage births, perhaps through parental leave, childcare or financial support. They can reduce some costs of raising children but may be expensive and may not overcome housing or career concerns.
Education, especially when access is broad and sustained, can expand life choices, employment and understanding of health and family planning. Effects normally take time.
Healthcare can lower preventable deaths and improve life expectancy. Reproductive and maternal healthcare can also support informed decisions and safer births.
Migration controls may change the rate and composition of movement, but enforcement is difficult and can separate families, restrict needed workers or divert movement into unsafe routes.
A strong evaluation names both the intended demographic effect and a possible environmental, economic, social or ethical limitation. It then judges suitability for a particular population structure. A country with an ageing population does not face the same decision as a rapidly growing city with inadequate sanitation.
Reading the population-environment system
The diagram is a reasoning tool, not a claim that population growth always causes environmental decline. Trace the pathway using the evidence in the question and explain how management strengthens, weakens or redirects it.
Worked application
A region has 2.4 million people and a land area of 12,000 km2. Its population density is 2,400,000÷12,000=200 people per km2. This average does not prove that every part is crowded. A population pyramid shows a broad base, while source data report rapid rural-to-urban migration and insufficient piped water in the main city. The evidence supports immediate investment in water, sanitation and planned housing, combined with education, healthcare and voluntary access to contraception. Restricting migration alone would not address natural increase or existing service shortages. The best judgement links short-term infrastructure to longer-term, rights-respecting demographic choices and recognises that each measure acts over a different time scale.
Common misconceptions
“Population density and distribution mean the same thing.” Density is a numerical average per area; distribution describes the spatial pattern.
“A broad pyramid base proves that the total population is large.” It shows age structure. A small country can have a broad base, and a large country can have a narrow one.
“Every working-age person is employed.” The pyramid category is age-based and does not provide employment status.
“Immigration means leaving a country.” Immigration is entry; emigration is departure.
“Rural-to-urban migration is the only cause of urbanisation.” Natural increase and settlement expansion or reclassification can also contribute.
“Population growth always produces more pollution.” Consumption, technology, infrastructure and regulation mediate the relationship.
“One population policy is suitable everywhere.” Suitability depends on age structure, rights, service capacity, economic needs and time scale.
Assessment guidance
When calculating density, show the division and include people per km2. When interpreting a population pyramid, quote age groups, compare both populations directly and distinguish evidence from a possible explanation. For population impacts, build a chain such as rapid growth to housing shortage to informal settlement to inadequate sanitation to polluted water and disease risk. A discuss question needs benefits, limitations and a reasoned judgement. Do not award yourself a conclusion merely by saying a policy is “effective”. State who can access it, how quickly it acts, whether it respects choice, what it costs and whether it matches the population structure shown in the source.
Retrieval practice
Distinguish population density from population distribution and calculate density for a population of 750,000 living on 3,000 km2.
Identify three features you would compare on two population pyramids.
Explain the difference between immigration, emigration, push factors and pull factors.
Build one causal chain from rapid urban growth to water pollution.
Give one benefit and one limitation each for contraception access, education and migration control.
Explain why income group alone cannot determine a country's population structure.
