Introduction
Species extinction is one of the most pressing global challenges and a core theme in IB Environmental Systems and Societies (ESS). The 2026 syllabus places extinction at the intersection of ecology, human activity, and sustainability. In exams, you’ll often be asked to explain why species go extinct and to evaluate strategies for preventing further losses.
To score highly, you need more than just definitions—you must connect ecological processes with human pressures, apply systems thinking, and use case studies effectively. This guide will show you exactly how to explain species extinction in ESS exams with clarity and precision.
Quick Start Checklist: Explaining Extinction in ESS
- Understand natural vs human-driven extinction.
- Learn the main causes: habitat loss, overexploitation, pollution, climate change, invasive species.
- Use case studies to provide evidence.
- Apply systems thinking: link ecological, social, and economic factors.
- Practice using command terms like “explain,” “evaluate,” and “discuss.”
- Be ready for Paper 1 data-response and Paper 2 essays on extinction.
What is Extinction?
Extinction occurs when a species has no surviving members. While extinction has always been part of natural processes (e.g., the dinosaurs), the current rate of extinction is much higher than the natural background rate due to human activities. ESS students must show awareness of this context and its implications for biodiversity and sustainability.
Causes of Species Extinction
1. Habitat Loss and Fragmentation
- Deforestation, agriculture, and urban expansion destroy natural habitats.
- Fragmented ecosystems isolate populations, reducing genetic diversity.
- Example: Orangutans in Borneo losing rainforest habitat to palm oil plantations.
2. Overexploitation
- Hunting, fishing, and trade drive species toward extinction.
- Example: Passenger pigeon hunted to extinction in North America.
- Example: Bluefin tuna populations drastically reduced by overfishing.
3. Pollution
- Chemicals, plastics, and waste disrupt ecosystems.
- Example: Amphibians sensitive to pollutants face global population declines.
- Example: Marine animals ingesting plastics suffer reduced survival.
4. Climate Change
- Rising temperatures shift habitats and migration patterns.
- Coral bleaching from warming oceans causes loss of reef ecosystems.
- Polar bears face extinction threats as sea ice disappears.
5. Invasive Species
- Non-native species outcompete, prey on, or bring diseases to native species.
- Example: Cane toads in Australia disrupt local ecosystems.
- Example: Rats and cats introduced to islands causing bird extinctions.
Systems Thinking and Extinction
In ESS, extinction is never explained by a single cause. Instead, examiners expect you to use systems thinking:
- Show how human activities (e.g., agriculture) lead to habitat loss.
- Explain how reduced biodiversity weakens ecosystems, making them less resilient.
- Link ecological consequences to social and economic impacts (e.g., fisheries collapse → food insecurity).
Case Studies for Extinction
Case studies strengthen exam answers. Examples include:
- Dodo (Mauritius): Hunted by humans and impacted by invasive species.
- Tasmanian Tiger (Australia): Extinct due to hunting and habitat pressures.
- Amphibians worldwide: Declining from habitat loss, climate change, and disease.
- Coral reefs (global): Biodiversity hotspots at risk from warming oceans.
A good exam answer uses at least one global and one local example.
How Extinction is Tested in ESS Exams
Paper 1 (Data-Response)
- Graphs of declining populations or species richness.
- Questions like: “Explain why species X is at risk of extinction.”
Paper 2 (Structured and Essay Questions)
- Extended responses on drivers of extinction.
- Evaluation of conservation strategies (in-situ vs ex-situ).
- Questions linking extinction to sustainability and ethics.
Internal Assessment (IA)
- Students may study local species decline, e.g., comparing biodiversity across habitats or analyzing human impacts.
How to Write Strong Exam Answers
- Define key terms (e.g., extinction, biodiversity, endangered).
- State causes clearly, grouped into ecological and human-driven.
- Apply systems thinking by connecting causes to wider impacts.
- Use case studies for evidence.
- Conclude with evaluation, suggesting conservation solutions.
Common Mistakes to Avoid
- Listing causes without linking them (examiners want explanation, not just recall).
- Forgetting local examples—answers with only global case studies lose balance.
- Mixing up natural and human-driven extinction.
- Weak evaluation—ESS exams expect you to consider solutions and trade-offs.
Frequently Asked Questions (FAQs)
1. Do I need to know historical extinctions like the dinosaurs?
Not in detail. The syllabus focuses on recent and current extinctions, especially those linked to human activities.
2. Should I include conservation strategies in extinction answers?
Yes, especially when the command term is “evaluate” or “discuss.” Linking extinction to conservation shows higher-level understanding.
3. How do I revise extinction effectively?
Organize your notes around causes → examples → consequences → strategies. RevisionDojo’s ESS materials provide case study banks and practice exam questions designed for this structure.
Conclusion
In IB ESS 2026, explaining extinction requires more than definitions—you must show causes, evidence, and consequences within a systems-thinking framework. By using case studies, connecting ecological and human drivers, and evaluating strategies, you’ll be prepared for both Paper 1 and Paper 2 questions.
Call to Action
Want exam-ready extinction case studies and model answers? RevisionDojo has the best ESS revision resources, giving you structured notes, diagrams, and practice questions for the 2026 syllabus. Start preparing today and aim for a 7!
