Topic 1: Foundation

1.1 Perspectives

1.2 Systems

1.3 Sustainability

Topic 2: Ecology

2.1 Individuals, populations, communities, and ecosystems

2.2 Energy and biomass in ecosystems

2.3 Biogeochemical cycles

2.4 Climate and biomes

2.5 Zonation, succession and change

Topic 3: Biodiversity and conservation

3.1 Biodiversity and evolution

3.2 Human impact on biodiversity

3.3 Conservation and regeneration

Topic 4: Water

4.1 Water systems

4.1.1—Water movement drivers

4.1.2—Hydrological cycle

4.1.3—Hydrological cycle stores

4.1.4—Hydrological cycle flows

4.1.5—Human activity impacts

4.1.6—Water body steady state

4.1.7 (HL)—Water properties

4.1.8 (HL)—Oceans as carbon sink

4.1.9 (HL)—Ocean carbon sequestration

4.1.10 (HL)—Water temperature and density

4.1.11 (HL)—Stratification

4.1.12 (HL)—Ocean stratification increase

4.1.13 (HL)—Upwellings

4.1.14 (HL)—Thermohaline circulation

4.2 Water access, use and security

4.3 Aquatic food production systems

4.4 Water pollution

Topic 5: Land

5.1 Soil

5.2 Agriculture and food

Topic 6: Atmosphere and climate change

6.1 Introduction to the atmosphere

6.2 Climate change—causes and impacts

6.3 Climate change—mitigation and adaptation

6.4 Stratospheric ozone

Topic 7: Natural resources

7.1 Natural resources—uses and management

7.2 Energy sources—uses and management

7.3 Solid waste

Topic 8: Human populations and urban systems

8.1 Human populations

8.2 Urban systems and urban planning

8.3 Urban air pollution

HL.a Environmental law

HL.b Environmental economics

HL.c Environmental ethics

IB ESS HL 4.1.10 (HL)—Water temperature and density Question Bank

• Cold water below, warmer above

• Density differences restrict mixing → stratification

• Water densest at 4°C → freezing from surface down

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