Introduction
For HL students in IB Environmental Systems and Societies (ESS), the 2026 first assessment introduces more emphasis on international environmental law. While SL students focus on scientific and systems concepts, HL students must also understand how legal frameworks shape sustainability.
This topic is exam-relevant because it highlights the global nature of environmental problems—such as climate change, biodiversity loss, and pollution—and shows how international cooperation can (or cannot) solve them.
Quick Start Checklist for HL Students
When revising international law in ESS, make sure you can:
- Explain why environmental issues require international agreements.
- Identify key treaties relevant to ESS topics.
- Evaluate the successes and limitations of these treaties.
- Use case studies in exam answers.
- Link law to sustainability, ethics, and economics.
Why International Law Matters in ESS
Environmental problems often cross borders:
- Air pollution drifts across countries.
- Oceans are shared commons.
- Climate change affects the entire planet.
International law provides frameworks for cooperation, but its effectiveness depends on political will, enforcement, and equity.
Key Treaties and Agreements to Know
1. Montreal Protocol (1987)
- Target: ozone-depleting substances (CFCs).
- Success story: ozone layer is now recovering.
