The Montreal Protocol
Big idea: The Montreal Protocol (1987) is widely considered the most successful international environmental agreement, achieving near-universal participation and measurable results.
Key features
- Signed: 1987; entered into force 1989
- Participation: 198 countries — universal ratification (only UN treaty to achieve this)
- Targets: Phase-out schedules for ODS production and consumption
- Differentiated responsibility: Developing countries given longer timelines
- Multilateral Fund: Financial support for developing countries to transition
- Amendments: Strengthened multiple times (London, Copenhagen, Kigali)
Phase-out timeline
- CFCs: Phased out by 1996 (developed), 2010 (developing)
- Halons: Phased out by 1994 (developed), 2010 (developing)
- HCFCs: Being phased out by 2030 (developed), 2040 (developing)
- HFCs: Added in Kigali Amendment (2016) — also greenhouse gases
The Kigali Amendment (2016) added HFCs to the Montreal Protocol. HFCs dont harm ozone but are powerful greenhouse gases — so this also helps climate!
Exam tip: Questions often ask you to evaluate the Montreal Protocols success. Know both its achievements AND its limitations.
Evaluating the Montreal Protocol
Big idea: The Montreal Protocol has achieved remarkable success but also has limitations. It offers lessons for addressing other global environmental problems like climate change.
Successes
- >99% reduction in ODS production and consumption
- Ozone recovery: Hole stabilised and beginning to shrink
- Universal participation: All 198 UN members ratified
- Effective compliance: Few violations; strong monitoring
- Co-benefits: Avoided significant climate warming (CFCs are also GHGs)
- Technology transfer: Helped developing countries access alternatives
Limitations and challenges
- Slow recovery: Full recovery not expected until 2066 due to CFC persistence
- Illegal production: Some CFC smuggling still occurs
- Replacement problems: HCFCs and HFCs have their own issues (GHGs)
- Not transferable: Success factors may not apply to climate change
Why was it successful? (Lessons for climate)
- Clear scientific consensus on the problem
- Alternatives were available (industry could adapt)
- Relatively few major producers to regulate
- Costs concentrated in specific industries, not whole economy
- Strong financial support for developing countries
- Regular strengthening based on new science
Exam tip: Comparing Montreal Protocol (success) with Kyoto/Paris (challenges) is a common essay topic. Explain why ozone was easier to address than climate.
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IB-style question — the Montreal Protocol [3]
In 1987 most of the world's governments signed an international agreement to tackle the ozone problem.
Outline how the Montreal Protocol has helped to reduce ozone depletion. [3]
How to answer it, step by step
- What the agreement did
• It got countries to agree to phase out the gases that destroy ozone (like CFCs).
• Industries had to switch to safer, ozone-friendly substitutes. - Why it worked
• Almost every country signed and stuck to it, so CFC use fell worldwide.
• With fewer CFCs released, the ozone layer has slowly started to recover.
Final answer
Credit comes for explaining WHY it succeeded (near-global agreement + phase-out + recovery), not just naming the treaty — link the action to the result.
IB-style question — how effective was the Protocol? [7]
The Montreal Protocol is often called the most successful environmental treaty ever, yet the Antarctic ozone hole has still not fully closed.
To what extent has the Montreal Protocol been successful in solving the problem of ozone depletion? [7]
How to answer it, step by step
- Reasons it has worked well
• Nearly every country signed and CFC production has dropped hugely.
• Scientists now measure the ozone layer slowly healing, showing real results. - Reasons the job isn't finished
• CFCs already released stay in the air for decades, so recovery is very slow.
• Some replacement gases are powerful greenhouse gases, and a few countries still leak banned CFCs.
Final answer
For 'to what extent' you must reach a balanced judgement — say it is largely successful BUT not complete, and back each side with evidence.