Introduction
Many students preparing for IB Environmental Systems and Societies (ESS) ask: “Do I still need to study the ozone layer for the 2026 first assessment?” The answer is yes—but with a focus on stratospheric ozone depletion rather than climate change.
While climate change dominates the ESS syllabus, the ozone layer remains relevant because it shows how human activities can disrupt atmospheric systems and how international cooperation can solve global environmental problems. Understanding the ozone story also helps students see the difference between ozone depletion and the greenhouse effect, which are often confused in exams.
Quick Start Checklist for ESS Students
When revising the ozone layer, make sure you can:
- Define the ozone layer and its role in filtering UV radiation.
- Explain the causes of ozone depletion (CFCs, halons).
- Describe the environmental and health impacts of ozone thinning.
- Outline the Montreal Protocol as a case study in international cooperation.
- Distinguish clearly between ozone depletion and climate change.
The Ozone Layer in ESS
- Located in the stratosphere, the ozone layer absorbs harmful UV-B radiation.
- Without it, humans and ecosystems would face much higher exposure to UV radiation.
Causes of Ozone Depletion
- Chlorofluorocarbons (CFCs): once used in refrigerators, aerosols, air conditioners.
- Halons: used in fire extinguishers.
- Nitrous oxide (N₂O): agriculture and combustion, emerging as a concern.
