The Montreal Protocol, officially the Montreal Protocol on Substances That Deplete the Ozone Layer, is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion. It was agreed on 16 September 1987, and was entered into force on 1 January 1989. Since then, it has undergone several amendments and adjustments, with revisions agreed to in 1990 (London), 1992 (Copenhagen), 1995 (Vienna), 1997 (Montreal), 1999 (Beijing), 2007 (Montreal), 2016 (Kigali) and 2018 (Quito).
The Montreal Protocol has been ratified by 198 parties (197 states and the European Union), making it the first universally ratified treaty in United Nations history. Due to its widespread adoption and implementation, it has been hailed as an example of successful international co-operation. Former United Nations (UN) secretary-general Kofi Annan stated that it is "perhaps the single most successful international agreement to date has been the Montreal Protocol".
As a result of the Protocol, the ozone hole over Antarctica is slowly recovering. Climate projections indicate that the ozone layer will return to 1980 levels between 2040 across much of the world and 2066 over Antarctica.
Terms and purposes
The terms of the Montreal Protocol establish control measures, timelines, assessment and review, data reporting, methods of dealing with non-compliance, and measures to assist developing countries with compliance.
Timelines to phase out production and consumption of ozone-depleting substances (ODSs) covered by the Protocol are grouped by type. Specific ODS compounds belonging to each group are defined in the annexures to the Protocol.
Article 5 of the Protocol creates separate obligations for developing countries, allowing additional time to achieve compliance with the Protocol's control measures. Article 10 of the Protocol establishes a financial mechanism to help those countries achieve compliance.
Chlorofluorocarbons (CFCs) Phase-out Management Plan
The purpose of the Protocol is that each signatory states:
Recognizing that worldwide emissions of certain substances can significantly deplete and otherwise modify the ozone layer in a manner that is likely to result in adverse effects on human health and the environment. Determined to protect the ozone layer by taking precautionary measures to control equitably total global emissions of substances that deplete it with the ultimate objective of their elimination on the basis of developments in scientific knowledge
Acknowledging that special provision is required to meet the needs of developing countries
shall accept a series of stepped limits on CFC use and production, including:
- from 1991 to 1992 its levels of consumption and production of the controlled substances in Group I of Annex A do not exceed 150 percent of its calculated levels of production and consumption of those substances in 1986;
- from 1994 its calculated level of consumption and production of the controlled substances in Group I of Annex A does not exceed, annually, twenty-five percent of its calculated level of consumption and production in 1986.
- from 1996 its calculated level of consumption and production of the controlled substances in Group I of Annex A does not exceed zero.
The substances in Group I of Annex A are:
For this group, production and consumption in non-Article 5 Parties was frozen (at a 1986 base level) on July 1, 1989, with 75% phasedown by 1994 and complete phase-out by 1996. For Article 5 Parties, consumption and production was frozen (at a base level of the average of 1995–97 amounts), followed by a 50% phasedown by 2005, an 85% phasedown by 2007, and 100% phase-out by 2010. Some chemicals were given individual attention (Carbon tetrachloride; 1,1,1-trichloroethane). The phasing-out of the less damaging HCFCs only began in 1996 and will go on until a complete phasing-out is achieved by 2030.
Production and consumption levels of Annex A - Group II Halons (halon-1211, -2404, and -1301) in non-Article 5 Parties was frozen (at a 1986 base level) on January 1, 1992, with complete phase-out by 1994. For Article 5 Parties, production and consumption were frozen (at a base level of the average of 1995–97 amounts) on January 1, 2002, followed by a 50% phasedown by 2005 and complete phase-out by 2010.
The phasedown and phase-out schedules include a few exceptions for "essential uses" where no acceptable substitutes were initially found (for example, metered dose inhalers commonly used to treat asthma and chronic obstructive pulmonary disease were previously exempt). Another exception was made for Halon fire suppression systems used in submarines and aircraft (but not in general industry).
The provisions of the Protocol include the requirement that the Parties to the Protocol base their future decisions on the current scientific, environmental, technical, and economic information that is assessed through panels drawn from the worldwide expert communities. To provide that input to the decision-making process, advances in understanding on these topics were assessed in 1989, 1991, 1994, 1998 and 2002 in a series of reports entitled Scientific assessment of ozone depletion, by the Scientific Assessment Panel (SAP).
In 1990, the Parties to the Montreal Protocol established a Technology and Economic Assessment Panel (TEAP) as a technology and economics advisory body. The TEAP provides, at the request of Parties, technical information related to alternative technologies that have made it possible to virtually eliminate the use of ODSs that harm the ozone layer. The TEAP is also tasked by the Parties every year to assess and evaluate various technical issues, including evaluating nominations for essential use exemptions for CFCs and halons, and nominations for critical use exemptions for methyl bromide. TEAP's annual reports are a basis for the Parties' informed decision-making.
Numerous reports have been published by various inter-governmental, governmental and non-governmental organizations to catalogue and assess alternatives to the ozone depleting substances, since the substances have been used in various technical sectors, like in refrigeration, air conditioning, flexible and rigid foam, fire protection, aerospace, electronics, agriculture, and laboratory measurements.
Hydrochlorofluorocarbons (HCFCs) Phase-out Management Plan (HPMP)
Under the Montreal Protocol on Substances that Deplete the Ozone Layer, especially Executive Committee (ExCom) 53/37 and ExCom 54/39, parties to this protocol agreed to set 2013 as the year to freeze the consumption and production of HCFCs for developing countries. For developed countries, reduction of HCFC consumption and production began in 2004 and 2010, respectively, with 100% reduction set for 2020. Developing countries agreed to start reducing their consumption and production of HCFCs by 2015, with 100% reduction set for 2030.
Hydrochlorofluorocarbons, commonly known as HCFCs, are a group of human-made compounds containing hydrogen, chlorine, fluorine and carbon. They are not found anywhere in nature. HCFC production began to take off after countries agreed to phase out the use of CFCs in the 1980s, which were found to be destroying the ozone layer. Like CFCs, HCFCs are used for refrigeration, aerosol propellants, foam manufacture and air conditioning. Unlike the CFCs, however, most HCFCs are broken down in the lowest part of the atmosphere and pose a much smaller risk to the ozone layer. Nevertheless, HCFCs are very potent greenhouse gases, despite their very low atmospheric concentrations, measured in parts per trillion (ppt).
The HCFCs are transitional CFCs replacements, used as refrigerants, solvents, blowing agents for plastic foam manufacture, and fire extinguishers. In terms of ozone depletion potential (ODP), in comparison to CFCs that have ODP 0.6–1.0, these HCFCs have lower ODPs (0.01–0.5). In terms of global warming potential (GWP), in comparison to CFCs that have GWP 4,680–10,720, HCFCs have lower GWPs (76–2,270).
Hydrofluorocarbons (HFCs)
On 1 January 2019, the Kigali Amendment to the Montreal Protocol came into force. Under the Kigali Amendment countries promised to reduce the use of hydrofluorocarbons (HFCs) by more than 80% over the next 30 years. By 27 December 2018, 65 countries had ratified the Amendment. As of 31 October 2024, 160 states and the European Union have ratified the Amendment.
Produced mostly in developed countries, hydrofluorocarbons (HFCs) replaced CFCs and HCFCs. HFCs pose no harm to the ozone layer because, unlike CFCs and HCFCs, they do not contain chlorine. They are, however, greenhouse gases, with a high global warming potential (GWP), comparable to that of CFCs and HCFCs. In 2009, a study calculated that a fast phasedown of high-GWP HFCs could potentially prevent the equivalent of up to 8.8 Gt CO2-eq per year in emissions by 2050. A proposed phasedown of HFCs was hence projected to avoid up to 0.5C of warming by 2100 under the high-HFC growth scenario, and up to 0.35C under the low-HFC growth scenario. Recognizing the opportunity presented for fast and effective phasing down of HFCs through the Montreal Protocol, starting in 2009 the Federated States of Micronesia proposed an amendment to phase down high-GWP HFCs, with the U.S., Canada, and Mexico following with a similar proposal in 2010.
After seven years of negotiations, in October 2016 at the 28th Meeting of the Parties to the Montreal Protocol in Kigali, the Parties to the Montreal Protocol adopted the Kigali Amendment whereby the Parties agreed to phase down HFCs under the Montreal Protocol. The amendment to the Montreal Protocol commits the signatory parties to reduce their HFC production and consumption by at least 85 per cent from the annual average value in the period from 2011 to 2013. A group of developing countries including China, Brazil and South Africa are mandated to reduce their HFC use by 85 per cent of their average value in 2020–22 by the year 2045. India and some other developing countries – Iran, Iraq, Pakistan, and some oil economies like Saudi Arabia and Kuwait – will cut down their HFCs by 85 per cent of their values in 2024–26 by the year 2047.
On 17 November 2017, ahead of the 29th Meeting of the Parties of the Montreal Protocol, Sweden became the 20th Party to ratify the Kigali Amendment, pushing the Amendment over its ratification threshold ensuring that the Amendment would enter into force 1 January 2019.
Recent activities
The Parties to the Montreal Protocol, guided by the SAP, EEAP, and TEAP expert groups, continue to address ozone and climate challenges through Meetings of the Parties (MOP) to the Montreal Protocol, combined Conference of the Parties to the Vienna Convention (COP)-MOP meetings, and Open-ended Working Group (OEWG) meetings. Recent areas of focus and activities include:
- COP 12(I)/MOP 32 (2020): Replenishment of the MLF; critical-use exemptions for methyl bromide
- COP 12(II)/MOP 33 (2021): Trading of soon-to-be-obsolete technologies; energy-efficiency requirements; Parties' reporting and compliance
- OEWG 44 (2022): Study for replenishment of the MLF for 2024–26; continued emissions of CTC; African Parties' proposal to address the dumping of new but inefficient and obsolete cooling equipment in Africa
- MOP 34 (2022): illegal import of HVAC and other cooling equipment; gaps in global atmospheric monitoring of substances controlled by the Montreal Protocol; HFC-23 by-product emissions; illegal trade
- OEWG 45 (2023): illegal import and export of HVAC and other cooling equipment; stratospheric aerosol injection; HFC-23 emissions; very short-lived substances (VSLS) with climate- or ozone-damaging potential
- MOP 35 (2023): Decisions on MLF replenishment; feedstock uses of methyl bromide; import and export of prohibited cooling equipment (see entry on environmental dumping)
- OEWG 46 (2024): Feedstock uses of controlled substances; management of recovered/recycled/reclaimed halons; metered-dose inhalers with low-GWP propellants; improving access to climate-friendly cooling equipment in Article 5 Parties
- COP 13/MOP 36 (2024): Decisions on HFC-23 emissions and data reporting forms; LRM; VSLS; feedstocks; enhancing regional and global atmospheric monitoring; avoiding imports of energy-inefficient cooling products.
History
In 1974, the chemists Frank Sherwood Rowland and Mario Molina at the University of California, Irvine began studying the impacts of CFCs in the Earth's atmosphere. They discovered that CFC molecules were stable enough to remain in the atmosphere until they rose to the middle of the stratosphere, where they would be broken down by ultraviolet radiation and release a chlorine atom. Rowland and Molina then proposed that these chlorine atoms might be expected to cause the breakdown of large amounts of ozone (O3) in the stratosphere. In 1976, the U.S. National Academy of Sciences released a report that confirmed the scientific credibility of the ozone depletion hypothesis.