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IB ESS HL Study Guide & Review

Integrate environmental systems and evidence with legal, economic and ethical lenses, then build the sustained source synthesis and two-essay judgment required for current IB ESS HL.

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  1. 01Learn concepts
  2. 02Practise questions
  3. 03Review mistakes

Syllabus knowledge tree

Explore the IB ESS HL syllabus

The current IB ESS HL syllabus connects perspectives, systems and sustainability across Foundation and seven environmental Topics, with additional depth and three lenses: environmental law, environmental and ecological economics, and environmental ethics. Use the live map for exact Topic navigation.

8
syllabus groups
30
mapped topics

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Explore the course units and topics. Sign in to open the full mastery workspace and see your progress.

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
4.2 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

How to study IB ESS HL

IB ESS HL requires more than adding three lens definitions to SL notes. Use the syllabus map to connect each environmental issue to systems and sustainability, then deliberately change the analysis: law asks who has authority and whether enforcement works; environmental and ecological economics asks how incentives, valuation and distribution shape choices; ethics asks whose interests count and how competing principles support a judgment. Build evidence records that can survive this change of lens.

Use Concept to compare analytical models, Mastery to retrieve examples and lens criteria, and the Question Bank for sustained case-study and essay practice. After marking, locate the first breakdown: system connection, source synthesis, lens selection, evidence, counterargument or judgment. Repair that decision before completing another full response.

Practise HL issues through distinct lenses

Change the analytical method deliberately for law, environmental and ecological economics, ethics, source synthesis and sustained two-essay performance.

Environmental law

Authority, agreements, regulation, compliance and enforcement

Identify the jurisdiction, legal instrument, responsible actors and enforcement mechanism. Use evidence to judge effectiveness, then distinguish weak design from weak implementation and explain who gains or loses.

Practise environmental law

Environmental and ecological economics

Externalities, incentives, valuation, distribution and natural capital

Define the economic failure or trade-off, identify incentives and distributional effects, then compare policy tools using environmental outcomes, efficiency, equity, stakeholder impacts and important limits of monetary valuation.

Practise environmental economics

Environmental ethics

Value systems, moral standing, justice and intergenerational responsibility

Name the competing ethical principles and whose interests receive standing. Apply each position to the same evidence, expose its limitation, then reach a justified judgment rather than listing viewpoints.

Practise environmental ethics

HL Paper 1 source synthesis

Unseen case study, quantitative evidence and extended evaluation

Build a source map before answering: claim, evidence, scale, stakeholder, limitation and relevant course model. Integrate sources across the response and make each evaluation point test a specific inference.

Practise HL case studies

HL Paper 2 two-essay preparation

Section A data work and two structured essays

Prepare flexible evidence across several issues, then practise planning two different arguments under one time limit. Allocate evidence, counterargument and judgment explicitly so the second essay remains analytical and complete.

Open HL exam practice

Where to start

Start from one precise Topic or lens weakness, or use mixed HL questions to locate the first failed analytical decision.

Choose your starting point

  1. I know the weak Topic or lens

    Open its exact syllabus position and identify the system, evidence and analytical lens that must interact.

    Browse the HL syllabus

  2. The failure is unclear

    Attempt a mixed set and stop at the earliest repeated breakdown in synthesis, lens use or judgment.

    Open mixed HL questions

Choose the right starting point

  1. Map issue and evidence

    Define boundaries, stocks, flows, feedback and stakeholders before selecting the evidence that explains the issue.

    Review a Concept

  2. Apply the right lens

    Use legal, economic or ethical criteria to change the analysis rather than adding a label afterwards.

    Check Mastery

  3. Synthesize and judge

    Integrate sources, examples and counterarguments, reach a qualified conclusion and repair the first weak decision.

    Practise HL questions

IB ESS HL assessment format

External assessment contributes 80% and the individual investigation contributes 20%. HL preparation must sustain unseen case-study analysis and two structured essays across common content and the three lenses.

Paper / componentQuestionsTime% of grade
Paper 170 marksCompulsory questions analysing and evaluating data in a previously unseen case study.How to prepare: Practise sustained source mapping and synthesis, connecting broader and deeper HL content to evidence throughout the two-hour case study.2 hours30%
Paper 280 marksSection A has 40 marks of short-answer and data-based questions; Section B requires two structured essays from three choices for 40 marks.How to prepare: Build flexible evidence for two different arguments and practise applying the legal, economic and ethical lenses without sacrificing analysis in the second essay.2 hours 30 minutes50%
Individual investigation30 marksOne individual written investigation report of no more than 3,000 words, internally assessed and externally moderated.How to prepare: Develop a focused inquiry, appropriate method, transparent processing, evidence-based conclusion and evaluation tied to specific methodological limitations.10 recommended course hours20%

SourceInternational Baccalaureate Organization · Environmental systems and societies guideIB Environmental systems and societies · First assessment May 2026

IB ESS HL questions

HL has greater breadth and depth, longer external assessment and three required lenses: environmental law, environmental and ecological economics, and environmental ethics. HL Paper 2 also requires two structured essays, while SL requires one.

Select the lens that changes the analysis. Law tests authority, enforcement and effectiveness; economics tests incentives, valuation and distribution; ethics compares moral standing and principles. Apply the criteria to evidence before reaching a qualified judgment.

Practise building a source map across the full unseen case study: claim, evidence, scale, stakeholder, limitation and relevant course model. Sustain links between sources and use the lenses only where they clarify analysis or evaluation.

No. SL and HL use the same individual investigation model, 30 marks, maximum 3,000-word report and six criteria. The weighting differs: it contributes 25% at SL and 20% at HL.