ESS topic 6.2 Climate change causes and impacts - SL and HL (new syllabus)

Climate (6.2.1)

The average conditions of temperature and precipitation in a region over many years (typically 30 years or more). Example: The Mediterranean region has hot, dry summers and mild, wet winters.

Weather (6.2.1)

The day-to-day conditions of the atmosphere at a specific time and place. Example: Today's forecast shows rain and 15°C temperatures.

Anthropogenic emissions (6.2.2)

Gases and particles released into the atmosphere as a result of human activities. Example: Carbon dioxide from burning fossil fuels or methane from livestock farming.

Ice cores (6.2.3)

Cylindrical samples of frozen water extracted from glaciers and ice sheets. Example: Samples drilled from Antarctic ice revealing atmospheric composition from 800,000 years ago.

Tree rings (6.2.3)

Annual growth layers in woody plants that vary in thickness based on environmental conditions. Example: Wide rings indicating good growth from warmer, wetter years in Alaska.

Deposited sediments (6.2.3)

Layers of material that settle at the bottom of water bodies or on land surfaces. Example: Pollen grains preserved in lake beds showing past vegetation patterns.

Global warming (6.2.4)

The long-term increase in Earth's average surface temperature. Example: Average global temperatures have risen approximately 1.1°C since pre-industrial times.

Greenhouse effect (6.2.4)

The process by which certain atmospheric gases trap heat energy, warming Earth's surface. Example: Water vapor, carbon dioxide, and methane absorb infrared radiation and re-emit it.

Climate change (6.2.4)

Broad range of changes happening to Earth's systems, including temperature, precipitation patterns, and sea levels. Example: Shifting rainfall patterns in the Sahel, melting polar ice, and more frequent extreme weather events.

Greenhouse gases (GHGs) (6.2.4)

Atmospheric gases that absorb and emit infrared radiation. Example: Carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), and water vapor.

Ecosystems (6.2.5)

Communities of living organisms interacting with their physical environment. Example: Coral reef systems, tropical rainforests, or Arctic tundra.

Resilience (6.2.5)

The capacity of a system to absorb disturbance and reorganize while maintaining its essential functions. Example: A diverse forest recovering from drought better than a monoculture plantation.

Biome shift (6.2.5)

Large-scale change in the dominant vegetation type of a region due to altered climate conditions. Example: Boreal forests expanding northward into tundra regions.

Coral bleaching (6.2.5)

The loss of symbiotic algae from coral tissues due to stress, particularly from elevated water temperatures. Example: Great Barrier Reef experiencing widespread bleaching events during marine heatwaves.

Desertification (6.2.5)

The degradation of land in arid, semi-arid, and dry sub-humid areas. Example: Expansion of the Sahara Desert into the Sahel region.

Ocean circulation (6.2.5)

Large-scale movement of water throughout the world's oceans driven by temperature, salinity, and wind. Example: The Atlantic Meridional Overturning Circulation (AMOC) transporting warm water northward.

Sea-level rise (6.2.5)

The increase in the average height of the ocean's surface. Example: Coastal flooding in low-lying island nations like the Maldives or Tuvalu.

Societies (6.2.6)

Organized groups of people living together with shared institutions, culture, and governance. Example: Indigenous communities in the Arctic, agricultural societies in Southeast Asia.

Socio-economic conditions (6.2.6)

The combined social and economic factors that characterize a population. Example: Income levels, education access, employment rates, and healthcare availability.

Infrastructure (6.2.6)

The basic physical systems and facilities necessary for society to function. Example: Roads, bridges, water supply systems, power grids, and hospitals.

Systems diagram (6.2.7)

A visual representation showing the components of a system and the relationships between them. Example: Diagram showing connections between solar input, albedo, temperature, and ice cover.

Feedback loop (6.2.7)

A process where the output of a system affects its own inputs. Example: Melting ice reducing albedo, which increases warming, which melts more ice.

Positive feedback (6.2.7)

A process that amplifies change in a system, moving it further from equilibrium. Example: Permafrost thawing releases methane, increasing warming, causing more thawing.

Negative feedback (6.2.7)

A process that reduces change in a system, stabilizing it toward equilibrium. Example: Increased CO₂ stimulates plant growth, which removes more CO₂ from the atmosphere.

Global energy balance (6.2.7)

The equilibrium between incoming solar radiation and outgoing terrestrial radiation. Example: Earth's surface temperature depends on the balance between absorbed and emitted energy.

Solar radiation (6.2.7)

Energy from the Sun in the form of electromagnetic waves. Example: Shortwave ultraviolet, visible light, and infrared energy reaching Earth.

Terrestrial albedo (6.2.7)

The fraction of incoming solar radiation reflected by Earth's surface and atmosphere. Example: Fresh snow reflects up to 90% of sunlight; dark ocean water reflects only 6%.

Planetary boundary (6.2.8)

A limit defining a safe operating space for humanity within Earth's systems. Example: The threshold for atmospheric CO₂ concentration beyond which risks increase significantly.

Proxy data (6.2.10) HL only

Preserved physical characteristics that substitute for direct measurements of past climate. Example: Tree ring widths, ice core gas bubbles, or coral growth bands.

Direct measurements (6.2.10) HL only

Observations made using instruments that measure variables in real-time. Example: Thermometer readings, satellite temperature sensors, or weather station data.

Indirect measurements (6.2.10) HL only

Estimates of past conditions based on preserved biological or physical indicators. Example: Pollen assemblages indicating past vegetation and moisture levels.

Dendrochronology (6.2.10) HL only

The scientific method of dating and analyzing tree ring patterns. Example: Using sequential ring patterns from bristlecone pines to reconstruct precipitation history.

Isotope measurements (6.2.10) HL only

Analysis of atomic variants to infer environmental conditions. Example: Oxygen-18 to oxygen-16 ratios in ice cores indicating past temperatures.

Pollen cores (6.2.10) HL only

Preserved plant pollen grains extracted from sediment layers. Example: Pollen from peat bogs showing vegetation changes over millennia.

Climate models (6.2.11) HL only

Mathematical representations of Earth's climate system using equations and computer simulations. Example: General Circulation Models (GCMs) predicting future temperature and precipitation patterns.

Hindcasting (6.2.11) HL only

Running models backward from present to reproduce known past climate. Example: Testing if a model correctly recreates the 20th century warming trend.

Uncertainty (6.2.11) HL only

The range of possible outcomes due to incomplete knowledge or natural variability. Example: Model projections showing temperature could rise 1.5-4°C depending on emissions.

Scenarios (6.2.12) HL only

Alternative possible futures based on different assumptions about human behavior and emissions. Example: Representative Concentration Pathways (RCPs) ranging from low to high emissions.

Tipping points (6.2.13) HL only

Critical thresholds where small changes trigger large, often irreversible shifts. Example: Amazon rainforest transitioning to savanna after deforestation reaches critical level.

Critical threshold (6.2.13) HL only

A specific value or condition beyond which system behavior fundamentally changes. Example: Ocean temperature above which coral bleaching becomes permanent.

Equilibrium (6.2.13) HL only

A stable state where a system's inputs and outputs are balanced. Example: Pre-industrial climate maintained relatively stable conditions for millennia.

Tipping cascades (6.2.14) HL only

Series of interconnected tipping points where one triggers others. Example: Greenland ice sheet collapse affecting ocean circulation, triggering Amazon dieback.

Climate justice (6.2.15) HL only

The fair treatment of all people regarding burdens and benefits of climate impacts and responses. Example: Island nations contributing minimally to emissions yet facing greatest threats.

Vulnerability (6.2.15) HL only

The degree to which a system is susceptible to harm from climate change. Example: Bangladesh's low elevation and dense population create high flood vulnerability.

Responsibility (6.2.15) HL only

The obligation to address climate change based on contributions to the problem. Example: Developed nations' historical emissions create greater responsibility for action.