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IB ESS›ESS SL
Revision Notes

IB Environmental Systems & Societies SL

Clear, student-friendly revision notes for every topic of the ESS course — systems and sustainability, ecology, biodiversity, water, land, the atmosphere, natural resources and urban systems — written for the syllabus with first examinations in 2026.

ESS SL · Revision Notes

Table of Contents

Click any topic to expand, then open a sub-topic to see its notes.

1

Foundations

Thinking in systems: perspectives, inputs and outputs, and what sustainability actually means.

16 notes▾
1.1

Perspectives

4▾
What Shapes a Perspective→ How Values Shape Environmental Views→ Worldviews and the Environment→ The Rise of the Environmental Movement→
1.2

Systems

5▾
Thinking in Systems→ Open, Closed and Isolated Systems→ Equilibrium and Feedback Loops→ Resilience and Tipping Points→ Using Models in ESS→
1.3

Sustainability

7▾
What Sustainability Means→ Sustainable Development and the SDGs→ Environmental Justice and Equity→ Measuring Sustainability with Indicators→ Citizen Science and Public Data→ Frameworks for Sustainable Thinking→ Rethinking Economic Models→
2

Ecology

Populations, energy flow, nutrient cycles, biomes, and how ecosystems change over time.

26 notes▾
2.1

Individuals, Populations, Communities & Ecosystems

7▾
How Ecological Systems Fit Together→ Classifying Species and Using Keys→ What Controls Population Size→ Patterns of Population Growth→ Human Populations in Ecosystems→ Sampling and Studying Populations→ How Ecosystems Keep Functioning→
2.2

Energy & Biomass in Ecosystems

9▾
Following Energy Through an Ecosystem→ Photosynthesis as an Energy Input→ Respiration and Energy Release→ Trophic Levels and Feeding Chains→ Building and Reading Food Webs→ Why Energy Is Lost at Each Level→ Biomass and Productivity→ Drawing Ecological Pyramids→ How Humans Disrupt Energy and Matter Flow→
2.3

Biogeochemical Cycles

4▾
Nutrient Cycles in Ecosystems→ Carbon Stores and Flows→ How Humans Alter the Carbon Cycle→ Cutting Our Impact on the Carbon Cycle→
2.4

Climate & Biomes

3▾
Weather Versus Climate→ Global Biomes and Their Distribution→ Circulating Air and Ocean Currents→
2.5

Zonation, Succession & Change

3▾
Zonation Along Environmental Gradients→ Succession and How Communities Change→ What Makes an Ecosystem Stable→
3

Biodiversity & Conservation

What biodiversity is worth, what is destroying it, and how it can be protected and rebuilt.

14 notes▾
3.1

Biodiversity & Evolution

4▾
Biodiversity and Ecosystem Resilience→ How Evolution Generates Diversity→ Measuring Biodiversity→ Managing Biodiversity in Practice→
3.2

Human Impact on Biodiversity

4▾
What Is Driving Species Loss→ Judging Conservation Status→ Case Studies in Decline and Recovery→ Shared Resources and the Tragedy of the Commons→
3.3

Conservation & Regeneration

6▾
Why Preserving Biodiversity Matters→ Approaches to Conservation→ Designing and Managing Protected Areas→ Rewilding and Regeneration→ Biodiversity as a Planetary Boundary→ Competing Views on Conservation→
4

Water

Freshwater and ocean systems, water security, aquatic food production and pollution.

16 notes▾
4.1

Water Systems

2▾
How Water Moves Around the Planet→ How Humans Change the Water Cycle→
4.2

Water Access, Use & Security

3▾
What Decides Who Gets Water→ Ways to Increase Water Supply→ Tackling Water Scarcity→
4.3

Aquatic Food Production Systems

6▾
Food Webs in Aquatic Systems→ Rising Demand for Seafood→ Overfishing and Damaging Harvest Methods→ Protecting Fish Stocks→ Aquaculture and Fish Farming→ Warming Seas and Ocean Acidification→
4.4

Water Pollution

5▾
Where Water Pollution Comes From→ Plastics in Aquatic Systems→ Testing and Monitoring Water Quality→ Eutrophication and Its Consequences→ Managing Water Pollution→
5

Land

Soil as a living system, and how agriculture feeds a growing population without exhausting the ground it stands on.

7 notes▾
5.1

Soil

2▾
What Soil Is Made Of→ How Soil Behaves and What It Does→
5.2

Agriculture & Food

5▾
Land Use and Farming Systems→ Traditional Versus Industrial Farming→ Protecting and Restoring Soil→ How Sustainable Is Our Food System→ Food Security and Access→
6

Atmosphere & Climate Change

Atmospheric structure, greenhouse gases, the impacts of a warming climate, and the response to them.

12 notes▾
6.1

Introduction to the Atmosphere

2▾
What the Atmosphere Is Made Of→ How the Greenhouse Effect Works→
6.2

Climate Change: Causes & Impacts

4▾
Atmospheric Processes That Drive Climate→ What Is Causing Climate Change→ Climate Change and Ecosystems→ Climate Change and Human Societies→
6.3

Climate Change: Mitigation & Adaptation

3▾
Global Agreements and Decarbonisation→ Mitigating Climate Change→ Adapting to a Changing Climate→
6.4

Stratospheric Ozone

3▾
Ultraviolet Radiation and Living Things→ Ozone in the Stratosphere→ The Montreal Protocol and Ozone Recovery→
7

Natural Resources

Renewable and non-renewable resources, energy security, and what happens to everything we throw away.

11 notes▾
7.1

Natural Resources: Uses & Management

4▾
Treating Nature as Capital→ Putting a Value on Natural Capital→ Using Resources Sustainably→ Resource Security and the Choices Behind It→
7.2

Energy Sources: Uses & Management

3▾
Energy Sources and How Sustainable They Are→ Energy Demand and the Choices We Make→ Storing and Saving Energy→
7.3

Solid Waste

4▾
What Counts as Waste→ The Cost of Waste to People and Ecosystems→ How Waste Is Disposed Of→ Managing and Reducing Waste→
8

Human Populations & Urban Systems

Population dynamics, urbanisation, and the environmental cost of city living.

10 notes▾
8.1

Human Populations

3▾
How Human Populations Change→ Managing Population Growth→ Population Structure and Models→
8.2

Urban Systems & Urban Planning

4▾
What Makes an Area Urban→ Why Cities Grow→ Urban Sprawl and Expansion→ Planning Sustainable Cities→
8.3

Urban Air Pollution

3▾
Where Urban Air Pollution Comes From→ Cleaning Up Urban Air→ Acid Deposition and Its Effects→

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