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.
