Stratospheric Ozone Depletion

Planetary Boundary 8

Boundary Status

Status: Within boundary ✓
Control Variable: Stratospheric ozone concentration

• Current: Recovering (Antarctic ozone hole shrinking)
• Boundary: <5% reduction from pre-industrial O₃ concentration

Scientific Basis: The stratospheric ozone layer protects Earth from harmful UV radiation. Chlorofluorocarbons (CFCs) and other ozone-depleting substances (ODS) caused the Antarctic ozone hole (discovered 1985). The Montreal Protocol (1987) is the most successful environmental treaty, phasing out ODS globally. Ozone layer is now recovering and expected to return to 1980 levels by 2066.

Business Relevance

Historical Context

• CFCs: Used in refrigeration, air conditioning, aerosol propellants, solvents (1930s-1990s)
• Montreal Protocol Success: 99% of ODS phased out globally
• Kigali Amendment (2016): Phase-down of hydrofluorocarbons (HFCs)—ozone-safe but potent GHGs

Current Business Impacts

• Refrigeration & AC: Transition from HFCs to low-GWP alternatives (HFOs, natural refrigerants)
• Compliance: Reporting under Kigali Amendment
• Illegal Trade: Black market CFCs still seized (non-compliance in developing countries)

Key Standards & Frameworks

International Treaty

• Montreal Protocol on Substances that Deplete the Ozone Layer (1987) — Legally binding treaty
• Kigali Amendment (2016) — HFC phase-down

Disclosure Standards

• GRI 305 — Emissions (includes ODS in Scope 1)
• EU F-Gas Regulation — HFC phase-down in EU

Primary Source Documents

Scientific Foundation

• UN Environment Ozone Secretariat — Montreal Protocol implementation
• WMO/UNEP Ozone Assessment (2022) — Scientific status report
• NASA Ozone Watch — Real-time ozone hole monitoring

Policy Frameworks

• Montreal Protocol Text — Full treaty document
• Kigali Amendment Text

Recommended Metrics

Ozone-Depleting Substances (ODS)

• ODS Emissions: Tonnes of ODP (ozone depletion potential) weighted substances
• Common ODS: CFCs, HCFCs, halons, carbon tetrachloride, methyl bromide
• Reporting: GRI 305-6 (Emissions of ozone-depleting substances)

HFC Emissions (Climate Impact)

• HFC Emissions: Tonnes of CO₂e (high GWP: 1,300-14,800× CO₂)
• Refrigerant Leakage Rate: % of charge lost annually
• HFC Phase-down Progress: % transition to low-GWP alternatives

Alternative Refrigerants

• Natural Refrigerants: Ammonia (NH₃), CO₂ (R-744), hydrocarbons (propane, isobutane)
• HFOs (Hydrofluoroolefins): Low-GWP synthetic alternatives (GWP <10)

Montreal Protocol Success Story

Key Achievements:

• 99% ODS phase-out (2020)
• Antarctic ozone hole: Shrinking since 2000
• Climate co-benefit: Avoided 1-2°C additional warming by 2100
• Universal ratification: 197 parties (every UN member state)

Recovery Timeline:

• Mid-latitudes: Ozone returned to 1980 levels by ~2040
• Arctic: By ~2045
• Antarctic: By ~2066

Books

Technical Guidance

Carbon Accounting in Practice
Includes refrigerant emissions (HFCs) in Scope 1:

• GWP values for common refrigerants
• Fugitive emissions estimation
• Equipment leakage rates

Download PDF | View on Amazon

Related Pages

• Climate Change — HFCs as potent GHGs
• Novel Entities — Chemical substances regulation

Planetary Boundary Status: Stockholm Resilience Centre (2023) | Ozone Recovery: WMO/UNEP (2022) | Last updated: February 2026