IB Geography HL flashcards
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32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Dependency ratio
- The ratio of dependents (people aged under 15 and over 64) to the working-age population (15–64), expressed per 100; a high ratio indicates a heavy dependent load.
- Demographic Transition Model
- A five-stage model describing changes in birth and death rates as societies develop; natural increase is highest in stage 2 and near zero in stages 4 and 5.
- Doubling time
- The number of years for a population to double at a constant growth rate, approximated as 70 divided by the annual percentage growth rate.
- Population momentum
- The tendency of a population with a youthful age structure to keep growing for decades after fertility falls, because large cohorts enter reproductive age.
- Enhanced greenhouse effect
- The additional warming caused when human emissions of greenhouse gases trap outgoing longwave radiation, raising global mean temperatures above natural levels.
- Ecological footprint
- The area of biologically productive land and water, in global hectares, needed to supply a population's resources and absorb its wastes.
- Storm hydrograph
- A graph of river discharge over time after rainfall, showing rising limb, peak discharge, lag time, and falling limb; impermeable surfaces shorten lag time.
- Water scarcity
- Physical scarcity occurs when demand exceeds available supply; economic scarcity occurs when lack of infrastructure or finance prevents access to existing water.
- Thermohaline circulation
- A global ocean conveyor driven by differences in temperature and salinity; cold, salty, dense water sinks at high latitudes and drives deep currents.
- El Niño
- A periodic weakening or reversal of Pacific trade winds that pools warm water in the eastern Pacific, shifting rainfall and disrupting global weather patterns.
- Ocean acidification
- The lowering of ocean pH as dissolved carbon dioxide forms carbonic acid; it impairs calcifying organisms such as corals and shellfish.
- Bid-rent theory
- A model showing land value highest in the central business district and declining outward, producing concentric zones of different land uses.
- Megacity
- An urban agglomeration with more than 10 million inhabitants; most current megacities are in Asia and the Global South.
- Food security
- Reliable access to sufficient, safe, and nutritious food, depending on availability, access, utilisation, and stability of supply.
- Core–periphery model
- A model in which core regions concentrate capital and high-value activity, while peripheral regions supply labour and raw materials and remain less developed.
- Time–space convergence
- The reduction in the time and cost needed to move people, goods, and information over distance, driven by transport and digital technology.
- Transnational corporation
- A firm that operates production or sales in more than one country, shaping global production networks through outsourcing and foreign direct investment.
- Global shift
- The relocation of manufacturing from older industrial regions in Europe and North America to East and South Asia since the 1970s.
- Glocalisation
- The adaptation of global products, services, and marketing to local cultures and preferences while retaining an overarching global brand identity.
- Remittances
- Money sent by migrants to family in their home country; a major flow of income for many lower-income economies.
- Contour lines
- Lines on a map joining points of equal elevation; closely spaced contours indicate steep slopes, and V-shapes pointing uphill mark valleys.
- Systematic sampling
- Selecting data points at regular intervals, such as every tenth metre along a transect, to reduce bias and ensure even coverage.
- Spearman's rank correlation
- A test of the strength and direction of association between two ranked variables, calculated as rs = 1 − (6Σd²) ÷ (n(n² − 1)).
- Chi-squared test
- A statistical test comparing observed and expected frequencies, calculated as χ² = Σ((O − E)² ÷ E), with degrees of freedom (rows − 1)(columns − 1).
- Interquartile range
- The difference between the upper and lower quartiles of a data set; a robust measure of spread less affected by extreme values.
- Correlation versus causation
- A statistical association between two variables does not prove that one causes the other; a plausible causal mechanism and further evidence are required.
- Ecological fallacy
- The error of inferring individual behaviour from aggregate area data, assuming all people in an area share the area's average characteristics.
- Feedback loop
- A process in which a change in a system triggers further change; positive feedback amplifies it, negative feedback dampens or reverses it.
- Null hypothesis
- A statement that there is no significant relationship or difference between variables; statistical tests assess whether it can be rejected.
- Triangulation
- Using multiple methods, sources, or data sets to cross-check findings, strengthening the reliability and validity of conclusions.
- Mitigation versus adaptation
- Mitigation reduces the causes of climate change, such as emissions; adaptation reduces vulnerability to its impacts, such as flood defences.
- Choropleth map
- A map shading areas by the value of a variable; useful for showing rates or densities but potentially misleading when areas differ greatly in size.