IB Geography HL key terms

A bar chart showing the number of males and females in each age band of a population. Its shape reveals whether a population is growing, stable or ageing.

A model describing how birth and death rates change as a country develops, moving from high birth and death rates to low ones, with population growth fastest in the middle stages.

The difference between the number of births and deaths in a population in a year, usually expressed per 1,000 people. It excludes the effect of migration.

The number of people too young or too old to work, divided by the number of working-age people, usually shown per 100 workers. A high ratio means heavy pressure on workers.

A population in which the proportion of older people is rising, usually because of low birth rates and longer life expectancy. It increases demand for pensions and health care.

A government measure designed to reduce birth rates, such as China's former one-child policy, through incentives, penalties or contraception campaigns. It aims to slow population growth.

A government measure intended to raise birth rates, such as cash bonuses, paid parental leave or subsidised childcare. It is used where low fertility threatens the workforce.

The difference between immigration and emigration for a place over a period. A positive figure means more people arrived than left; a negative figure means the reverse.

Conditions that drive people away from a place (push), such as conflict or unemployment, and conditions that attract them elsewhere (pull), such as jobs or safety. Together they shape migration flows.

A person forced to flee across an international border because of war, persecution or disaster, and who is entitled to protection under international law. Distinct from someone displaced inside their own country.

The economic boost a country can gain when its working-age population grows faster than its dependent population, provided enough jobs and education exist to use that labour.

The extra warming caused when human emissions of gases such as carbon dioxide and methane trap more outgoing heat in the atmosphere than natural levels would.

A process where a change in the climate triggers another change that either amplifies the original change (positive feedback) or reduces it (negative feedback). Melting ice exposing dark ocean is an example.

The proportion of incoming solar radiation reflected by a surface. Ice and snow have high albedo, while dark ocean or forest has low albedo and absorbs more energy.

Action that reduces the causes of climate change, for example cutting greenhouse gas emissions, switching to renewable energy or protecting carbon sinks such as forests.

Adjusting to actual or expected climate impacts in order to reduce harm, for example building flood defences, drought-resistant crops or early-warning systems. It addresses consequences rather than causes.

A shortage of freshwater that limits human use, caused either by low physical supply (physical scarcity) or by lack of infrastructure and money to access it (economic scarcity).

A measure of how much of the available freshwater supply is withdrawn for human use. High stress means demand is close to or above what the system can sustainably provide.

An underground layer of rock or sediment that stores and transmits groundwater. Aquifers are recharged by rainfall and can be depleted if abstraction exceeds recharge.

The volume of water embedded in a product, such as the water used to grow a crop or make a garment. Trade in goods therefore moves water between countries indirectly.

The total volume of freshwater used to produce the goods and services consumed by a person, business or country, including water used abroad for imported products.

A graph showing river discharge over time in response to a rainfall event. A short lag time and high peak indicate a flashy catchment with rapid runoff.

The delay between the peak of rainfall and the peak of river discharge in a storm hydrograph. Short lag times increase flood risk because water reaches the channel quickly.

Nutrient enrichment of water, usually from fertiliser or sewage, that triggers algal blooms. Decay of the algae removes oxygen and can kill fish and other aquatic life.

The decrease in ocean pH caused by seawater absorbing carbon dioxide from the atmosphere. It harms organisms that build calcium carbonate shells and reefs.

The loss of colour in corals when heat or other stress makes them expel the microscopic algae that live inside their tissues and supply them with food. Prolonged bleaching can kill the reef.

A defined sea area managed to conserve ecosystems and restrict damaging activities such as industrial fishing or dredging. Well-enforced no-take zones allow fish stocks and habitats to recover.

Catching fish at a rate faster than populations can reproduce, causing stocks to decline. It disrupts food chains and threatens the livelihoods that depend on the fishery.

The largest catch that can be taken from a fish stock over time without reducing the population's ability to replenish itself. It is a target used in fisheries management.

The idea that shared resources such as open ocean or grazing land get overexploited because each user gains from taking more while the cost of depletion falls on everyone.

A situation where all people at all times have physical and economic access to sufficient, safe and nutritious food for an active and healthy life. It has availability, access and use dimensions.

An area, often urban and low-income, where residents lack reasonable access to affordable fresh food and rely on convenience stores or fast food instead.

Farming that mainly produces food for the farmer's own household rather than for sale. It is typically labour-intensive and vulnerable to drought and pests.

A crop grown primarily for sale rather than household consumption, such as coffee, cotton or palm oil. It can raise farm income but exposes growers to world price swings.

The spread of high-yield crop varieties, fertilisers, pesticides and irrigation from the mid-twentieth century, which sharply raised yields in parts of Asia and Latin America but widened inequalities.

The outward spread of a city into surrounding countryside at low density, usually driven by car use and cheap land. It raises infrastructure costs and consumes farmland.

The process by which wealthier residents move into a low-income urban area, raising rents and property values and often displacing existing communities.

Housing built by residents on land they do not formally own, often lacking secure tenure and basic services. Also called a shanty town or slum.

A company that operates in two or more countries, often placing production where costs are lowest. Its investment decisions can transform local economies and labour markets.

The relocation of manufacturing and some service activity from high-income countries towards lower-cost economies, especially in East and South Asia, since the late twentieth century.

The sequence of activities, places and firms involved in producing, processing and delivering a product to consumers. Mapping it shows where value is added and where power lies.

Investment by a firm or individual in productive assets located in another country, such as building a factory or buying a local company. It brings capital but can create dependency.

A designated area within a country where rules on tax, trade and foreign ownership differ from the rest of the economy in order to attract investment and export manufacturing.

A model describing uneven development, in which wealth and decision-making concentrate in core regions while periphery regions supply labour and raw materials and remain less developed.

The method used to choose data collection points, such as random, systematic or stratified sampling. The choice affects how representative the results are.

A statistical test measuring the strength and direction of a relationship between two ranked variables, giving a coefficient between -1 and +1. It shows association, not cause.

Information collected first-hand by the researcher for a specific investigation, for example through field measurements, questionnaires or interviews. It is tailored but costly to gather.

Information gathered by someone else and reused, such as census figures, satellite imagery or government statistics. It is quick and broad but may be out of date or inconsistent.

Software for storing, analysing and displaying data linked to locations, allowing layers such as population, relief and land use to be combined and mapped.

Collecting information about the Earth's surface from aircraft or satellites without physical contact, for example to monitor deforestation, urban growth or crop health over time.

Development that meets present needs without preventing future generations from meeting theirs, balancing economic growth, social wellbeing and environmental protection.

The area of land and water needed to supply a population with the resources it consumes and to absorb its wastes, expressed in global hectares.

The maximum population or level of use an environment can support indefinitely without degrading its resources, given current technology and consumption patterns.

The ability of a system, community or ecosystem to absorb disturbance and recover while keeping its essential functions and structure intact.

A formal process that predicts the likely environmental effects of a proposed project before approval, and sets conditions to reduce harm. It is a key tool in planning decisions.

Any person or group with an interest in a decision or place, such as residents, businesses, government or conservation groups. Their differing values explain many resource conflicts.