{{Short description|1987 treaty to protect the ozone layer}} {{multiple issues| {{Update|date=February 2025}} {{abbreviations|article|Somewhere part-way through the terms and purposes section there are so many similar abbreviations being used continuously that the text is an incomprehensible nightmare to look at.|date=January 2026}} {{overly detailed|date=January 2026}} {{Book farm|date=January 2026}} }} {{Use dmy dates|date=January 2022}} {{Infobox Treaty | name = Montreal Protocol | long_name = The Montreal Protocol on Substances That Deplete the Ozone Layer | date_signed = 16 September 1987<ref>{{cite web|url=https://www.unep.org/ozonaction/who-we-are/about-montreal-protocol|title=About Montreal Protocol|website=United Nations Environment Programme|date=29 October 2018 |access-date=10 October 2024}}</ref> | location_signed = Montreal | date_sealed = | date_effective = 1 January 1989 if 11 states have ratified by then | condition_effective = Ratification by 20 states | date_expiration = | signatories = 46 | ratifiers = 198 (all United Nations members, as well as the Cook Islands, Niue, the Holy See, Palestine, and the European Union) | depositor = Secretary-General of the United Nations | languages = Arabic, Chinese, English, French, Russian, and Spanish | website = | wikisource = }} [[File:Ozone Hole 2024 Update.webp|thumb|The Antarctic ozone hole (October 2024)]] [[File:Retrospective video on the Montreal Protocol.ogv|thumb|2012 retrospective video by NASA on the Montreal Protocol]]

The '''Montreal Protocol''', officially the '''Montreal Protocol on Substances That Deplete the Ozone Layer''',<ref name="UIA">{{Cite web |url=https://uia.org/s/or/en/1100031640 |url-access= |title=Montreal Protocol on Substances that Deplete the Ozone Layer |author1=Staff writer |year=2024 |department=UIA Global Civil Society Database |website=uia.org |publisher=Union of International Associations |agency=Yearbook of International Organizations Online |location=Brussels, Belgium |format= |arxiv= |asin= |bibcode= |doi= |isbn= |issn= |jfm= |jstor= |lccn= |mr= |oclc= |ol= |osti= |pmc= |pmid= |rfc= |ssrn= |zbl= |id= |access-date=17 January 2025 |via= |quote= |trans-quote= }}</ref> 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 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).<ref>{{Cite web|url=https://sdg.iisd.org:443/news/kigali-amendment-enters-into-force-bringing-promise-of-reduced-global-warming/|title=Kigali Amendment Enters into Force, Bringing Promise of Reduced Global Warming {{!}} News {{!}} SDG Knowledge Hub {{!}} IISD|last=Hub|first=IISD's SDG Knowledge|language=en-US|access-date=2019-03-07}}</ref><ref>{{Cite web|url=https://www.bbc.com/news/science-environment-37665529|title=Deal reached on HFC greenhouse gases|first=Matt|last=McGrath|date=15 October 2016|publisher=BBC}}</ref><ref>{{cite web |url=https://ozone.unep.org/treaties/montreal-protocol-substances-deplete-ozone-layer/the-evolution-of-the-montreal-protocol|title=The Evolution of the Montreal Protocol|publisher=United Nations Environment Programme Ozone Secretariat |access-date=2 November 2024 |archive-url=https://web.archive.org/web/20240822180439/https://ozone.unep.org/treaties/montreal-protocol-substances-deplete-ozone-layer/the-evolution-of-the-montreal-protocol |archive-date=22 August 2024 |url-status=live }}</ref>

The Montreal Protocol has been ratified by 198 parties (197 states and the European Union),<ref name="ozone.unep.org">{{cite web |url=http://ozone.unep.org/Ratification_status/ |title=Status of Ratification – The Ozone Secretariat |publisher=Ozone.unep.org |access-date=10 March 2008 |archive-url=https://web.archive.org/web/20141008112847/http://ozone.unep.org/Ratification_status/ |archive-date=8 October 2014 |url-status=dead }}</ref> making it the first universally ratified treaty in United Nations history.<ref>{{cite web |url=http://www.unep.org/Documents.Multilingual/Default.asp?DocumentID=2666&ArticleID=9010&l=en |title=UNEP press release: 'South Sudan Joins Montreal Protocol and Commits to Phasing Out Ozone-Damaging Substances' |publisher=Unep.org |access-date=11 July 2012 |archive-date=4 March 2016 |archive-url=https://web.archive.org/web/20160304093536/http://www.unep.org/Documents.Multilingual/Default.asp?DocumentID=2666&ArticleID=9010&l=en |url-status=dead }}</ref> 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 "perhaps the single most successful international agreement to date has been the Montreal Protocol".<ref>{{cite web |url=http://www.theozonehole.com/montreal.htm |title=The Ozone Hole – The Montreal Protocol on Substances that Deplete the Ozone Layer |publisher=Theozonehole.com |date=16 September 1987 |access-date=17 August 2007 |archive-date=12 September 2012 |archive-url=https://archive.today/20120912223944/http://www.theozonehole.com/montreal.htm |url-status=dead }}</ref><ref>{{Cite web|url=https://www.un.org/en/events/ozoneday/background.shtml|title=Background for International Day for the Preservation of the Ozone Layer – 16 September|website=un.org|language=EN|access-date=2017-05-28}}</ref>

As a result of the Protocol, the ozone hole over Antarctica is slowly recovering.<ref>Ewenfeldt B, "Ozonlagret mår bättre", ''Arbetarbladet 12-9-2014, p. 10.''</ref><ref>{{Cite journal |last1=Barnes |first1=Paul W. |last2=Bornman |first2=Janet F. |last3=Pandey |first3=Krishna K. |last4=Bernhard |first4=Germar H. |last5=Bais |first5=Alkiviadis F. |last6=Neale |first6=Rachel E. |last7=Robson |first7=Thomas Matthew |last8=Neale |first8=Patrick J. |last9=Williamson |first9=Craig E. |last10=Zepp |first10=Richard G. |last11=Madronich |first11=Sasha |last12=Wilson |first12=Stephen R. |last13=Andrady |first13=Anthony L. |last14=Heikkilä |first14=Anu M. |last15=Robinson |first15=Sharon A. |date=November 2021 |title=The success of the Montreal Protocol in mitigating interactive effects of stratospheric ozone depletion and climate change on the environment |url=https://onlinelibrary.wiley.com/doi/10.1111/gcb.15841 |journal=Global Change Biology |language=en |volume=27 |issue=22 |pages=5681–5683 |doi=10.1111/gcb.15841 |bibcode=2021GCBio..27.5681B |issn=1354-1013|hdl=10138/346953 |hdl-access=free }}</ref> Climate projections indicate that the ozone layer will return to 1980 levels between 2040 across much of the world and 2066 over Antarctica.<ref>{{cite news|title=Ozone Layer on Track to Recovery: Success Story Should Encourage Action on Climate|url=http://www.unep.org/newscentre/Default.aspx?DocumentID=2796&ArticleID=10978&l=en|access-date=18 September 2014|agency=UNEP|publisher=UNEP|date=10 September 2014|archive-date=13 September 2014|archive-url=https://web.archive.org/web/20140913031932/http://www.unep.org/newscentre/default.aspx?DocumentID=2796&ArticleID=10978&l=en|url-status=dead}}</ref><ref>{{cite journal|author1=Susan Solomon|author2=Anne R. Douglass|author3=Paul A. Newman|title=The Antarctic ozone hole: An update|journal=Physics Today|volume=67|issue=7|pages=42–48|date=July 2014|doi=10.1063/PT.3.2449|bibcode=2014PhT....67g..42D |doi-access=free|hdl=1721.1/99159|hdl-access=free}}</ref><ref>{{Cite web|url=https://www.canada.ca/en/environment-climate-change/corporate/international-affairs/partnerships-organizations/ozone-layer-depletion-montreal-convention.html|title=Ozone layer depletion: Montreal Protocol|last=Canada|first=Environment and Climate Change|date=2015-02-20|website=aem|access-date=2020-04-22}}</ref><ref name=":1">{{Cite journal |last=World Meteorological Organization (WMO) |date=2022 |title=Scientific Assessment of Ozone Depletion: 2022 |url=https://ozone.unep.org/system/files/documents/Scientific-Assessment-of-Ozone-Depletion-2022-Executive-Summary.pdf |journal=GAW Report |publisher=WMO |publication-place=Geneva |issue=278 |pages=i}}</ref>

== 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.<ref name=":0">{{Cite web|title=The Montreal Protocol on Substances that Deplete the Ozone Layer {{!}} Ozone Secretariat|url=https://ozone.unep.org/treaties/montreal-protocol/montreal-protocol-substances-deplete-ozone-layer|website=ozone.unep.org|access-date=2026-01-28}}</ref>

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.<ref name=":0" />

Article 5 of the Protocol creates separate obligations for developing countries, allowing additional time to achieve compliance with the Protocol's control measures.<ref>{{Cite web|title=Article 5: Special situation of developing countries {{!}} Ozone Secretariat|url=https://ozone.unep.org/treaties/montreal-protocol/articles/article-5-special-situation-developing-countries|website=ozone.unep.org|access-date=2026-01-28}}</ref> Article 10 of the Protocol establishes a financial mechanism to help those countries achieve compliance.<ref>{{Cite web|title=Article 10: Financial mechanism {{!}} Ozone Secretariat|url=https://ozone.unep.org/treaties/montreal-protocol/articles/article-10-financial-mechanism|website=ozone.unep.org|access-date=2026-01-28}}</ref>

=== Chlorofluorocarbons (CFCs) Phase-out Management Plan ===

The purpose of the Protocol is that each signatory states:

{{blockquote|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:

{{block indent|<!-- Needed for indent on mobile -->{{plainlist| * 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:

* {{chem2|CFCl3}} (CFC-11) * {{chem2|CF2Cl2}} (CFC-12) * {{chem2|C2F3Cl3}} (CFC-113) * {{chem2|C2F4Cl2}} (CFC-114) * {{chem2|C2F5Cl}} (CFC-115)

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. <ref>{{Cite web |title=The Montreal Protocol on Substances that Deplete the Ozone Layer {{!}} Ozone Secretariat |url=https://ozone.unep.org/treaties/montreal-protocol#:~:text=Treaty%20relevant%20annex-,The%20Montreal%20Protocol%20on%20Substances%20that%20Deplete%20the%20Ozone%20Layer,entered%20into%20force%20in%201989. |access-date=2026-04-04 |website=ozone.unep.org}}</ref>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).<ref>{{Cite web|url=http://ozone.unep.org/en/assessment-panels/scientific-assessment-panel|title=Scientific Assessment Panel {{!}} OZONE SECRETARIAT|website=ozone.unep.org|language=en|access-date=2018-04-23|archive-url=https://web.archive.org/web/20180424202422/http://ozone.unep.org/en/assessment-panels/scientific-assessment-panel|archive-date=24 April 2018|url-status=dead}}</ref>

In 1990, the Parties to the Montreal Protocol established a Technology and Economic Assessment Panel (TEAP) as a technology and economics advisory body.<ref>{{Cite web|url=http://ozone.unep.org/en/assessment-panels/technology-and-economic-assessment-panel|title=Technology and Economic Assessment Panel {{!}} OZONE SECRETARIAT|website=ozone.unep.org|language=en|access-date=2018-04-23|archive-url=https://web.archive.org/web/20180126070701/http://ozone.unep.org/en/assessment-panels/technology-and-economic-assessment-panel|archive-date=26 January 2018|url-status=dead}}</ref> 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.<ref>{{cite web |title=Use of ozone depleting substances in laboratories |publisher=TemaNord |year=2003 |page=516 |url=http://norden.diva-portal.org/smash/get/diva2:796602/FULLTEXT01.pdf |archive-url=https://web.archive.org/web/20151121220053/http://norden.diva-portal.org/smash/get/diva2:796602/FULLTEXT01.pdf |archive-date=21 November 2015 }}</ref><ref>{{cite web |url=http://homer.ornl.gov/nuclearsafety/nsea/oepa/guidance/ozone/phaseout.pdf |title=Guidance on the DOE Facility Phaseout of Ozone-Depleting Substances |year=1995 |access-date=2007-12-03 |url-status=dead |archive-url=https://web.archive.org/web/20080227052411/http://homer.ornl.gov/nuclearsafety/nsea/oepa/guidance/ozone/phaseout.pdf |archive-date=27 February 2008 }}{{page needed|date=January 2026}}</ref>

=== 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.<ref>{{Cite web|url=https://ozone.unep.org/montreal-protocol-substances-deplete-ozone-layer/32506|title=The Montreal Protocol on Substances that Deplete the Ozone Layer|website=United Nations Environment Programme|access-date=16 November 2018|archive-date=14 October 2018|archive-url=https://web.archive.org/web/20181014170949/http://ozone.unep.org/montreal-protocol-substances-deplete-ozone-layer/32506|url-status=dead}}</ref>

Hydrochlorofluorocarbons, commonly known as HCFCs, are a group of human-made compounds containing hydrogen, chlorine, fluorine and carbon.<ref>{{Cite web |last=Canada |first=Environment and Climate Change |date=2025-06-02 |title=Hydrochlorofluorocarbons (HCFCs) |url=https://www.canada.ca/en/environment-climate-change/services/canadian-environmental-protection-act-registry/substances-list/toxic/schedule-1/hydrochlorofluorocarbons.html |access-date=2026-04-04 |website=www.canada.ca}}</ref> 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.<ref>{{Cite web |title=An International Climate Success Story: HCFCs |url=https://clcouncil.org/blog/international-success-story-hcfc/ |access-date=2026-04-04 |website=Climate Leadership Council |language=en-US}}</ref> 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).<ref>{{cite book |author=Intergovernmental Panel on Climate Change |year=2007 |title=Climate change 2007: The physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change |editor1=Solomon, S. |editor2=Qin, D. |editor3=Manning, M. |publisher=Cambridge University Press |location=Cambridge; New York |url=https://www.ipcc.ch/site/assets/uploads/2020/02/ar4-wg1-sum_vol_en.pdf |isbn=978-0521-88009-1}}{{page needed|date=January 2026}}</ref>

=== Hydrofluorocarbons (HFCs) ===

On 1 January 2019, the Kigali Amendment to the Montreal Protocol came into force.<ref>{{Cite web|url=https://ozone.unep.org/ozone-timeline|website=ozone.unep.org|access-date=2020-04-22|title=Ozone Timeline &#124; Ozone Secretariat }}</ref> Under the Kigali Amendment countries promised to reduce the use of hydrofluorocarbons (HFCs) by more than 80% over the next 30 years.<ref>{{Cite web|url=https://www.standardmedia.co.ke/article/2001308090/kigali-amendment-heralds-new-dawn-for-climate-change-action|title=Kigali Amendment heralds new dawn for climate change action|last=Msuya|first=Joyce|website=The Standard|language=en|access-date=2020-04-22}}</ref> By 27 December 2018, 65 countries had ratified the Amendment.<ref name="standardmedia_Msuya_20190102">{{Cite web| last = Msuya| first = Joyce | title = Kigali Amendment heralds new dawn for climate change action| work = The Standard| access-date=2 January 2019| url = https://www.standardmedia.co.ke/article/2001308090/kigali-amendment-heralds-new-dawn-for-climate-change-action |date=2 January 2019}}</ref> {{As of|2024|October|31}}, 160 states<ref name="UNTC">{{cite web |title=Amendment to the Montreal Protocol on Substances that Deplete the Ozone Layer |url=https://treaties.un.org/Pages/ViewDetails.aspx?src=IND&mtdsg_no=XXVII-2-f&chapter=27 |access-date=October 31, 2024 |website=United Nations Treaty Collective}}</ref> and the European Union<ref>{{Cite web |date=July 14, 2020 |title=Kigali Amendment hits milestone 100th ratification, boosting climate action |url=http://www.unep.org/news-and-stories/press-release/kigali-amendment-hits-milestone-100th-ratification-boosting-climate |url-status=live |archive-url=https://web.archive.org/web/20221103062228/http://www.unep.org/news-and-stories/press-release/kigali-amendment-hits-milestone-100th-ratification-boosting-climate |archive-date=November 3, 2022 |access-date=September 20, 2022 |website=United Nations Environment Programme}}</ref> 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.<ref>{{cite web |url=http://www.downtoearth.org.in/content/climate-irrationality |title=Climate of irrationality |publisher=Down To Earth |date=18 September 2012 |access-date=28 September 2012 |archive-date=1 October 2012 |archive-url=https://web.archive.org/web/20121001022841/http://www.downtoearth.org.in/content/climate-irrationality |url-status=dead }}</ref><ref>{{Cite web|url=https://www.canada.ca/en/environment-climate-change/services/air-pollution/issues/ozone-layer/depletion-impacts/substances.html#fn2|title=Ozone-depleting substances|last=Canada|first=Environment and Climate Change|date=2008-12-02|website=aem|access-date=2020-04-22}}</ref> 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.<ref>{{cite journal | vauthors = Velders GJ, Fahey DW, Daniel JS, McFarland M, Andersen SO | title = The large contribution of projected HFC emissions to future climate forcing | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 106 | issue = 27 | pages = 10949–54 | date = July 2009 | pmid = 19549868 | pmc = 2700150 | doi = 10.1073/pnas.0902817106 | bibcode = 2009PNAS..10610949V | doi-access = free }}</ref> 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.<ref>{{Cite journal|url=https://www.researchgate.net/publication/260830030|title=The role of HFCs in mitigating 21st century climate change|last1=Xu|first1=Yangyang|last2=Zaelke|first2=Durwood|last3=Velders|first3=Guus J. M.|last4=Ramanathan|first4=V|journal=Atmospheric Chemistry & Physics |date=2013-06-01|volume=13|issue=12 |page=6083 |doi=10.5194/acp-13-6083-2013 |doi-access=free |bibcode=2013ACP....13.6083X }}</ref> 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,<ref>{{Cite web|url=http://ozone.unep.org/Meeting_Documents/oewg/29oewg/OEWG-29-8E.pdf|title=Proposed amendment to the Montreal Protocol|date=4 May 2009|website=United Nations Environment Programme|access-date=17 May 2018}}</ref> with the U.S., Canada, and Mexico following with a similar proposal in 2010.<ref>{{Cite web|url=http://ozone.unep.org/Meeting_Documents/mop/22mop/MOP-22-5E.pdf|title=Proposed amendment to the Montreal Protocol|website=United Nations Environment Programme|date=30 July 2010|access-date=17 May 2018}}</ref>

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.<ref>{{Cite web|url=http://conf.montreal-protocol.org/meeting/mop/mop-28/final-report/English/MOP-28-12E.pdf|title=Report of the Twenty-Eighth Meeting of the Parties to the Montreal Protocol on Substances that Deplete the Ozone Layer|date=October 2016|access-date=25 January 2018|archive-date=26 January 2018|archive-url=https://web.archive.org/web/20180126012702/http://conf.montreal-protocol.org/meeting/mop/mop-28/final-report/English/MOP-28-12E.pdf|url-status=dead}}</ref> 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.<ref>{{Cite news|url=https://www.unenvironment.org/news-and-stories/press-release/montreal-protocol-celebrates-another-milestone-agreement-reduce|title=Montreal Protocol celebrates another milestone as agreement to reduce climate-warming gases is set to enter into force in 2019|work=UN Environment|access-date=2018-01-25|language=en}}</ref>

=== 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<ref>{{Cite web |title=Summary report 23–27 November 2020 |url=https://enb.iisd.org/events/12th-meeting-conference-parties-vienna-convention-part-i-and-32nd-meeting-parties-montreal-5 |access-date=2025-08-27 |website=IISD Earth Negotiations Bulletin |language=en}}</ref><ref>{{Cite web |title=Post-session documents {{!}} Ozone Secretariat |url=https://ozone.unep.org/meetings/thirty-second-meeting-parties/post-session-documents |access-date=2025-08-27 |website=ozone.unep.org}}</ref> * COP 12(II)/MOP 33 (2021): Trading of soon-to-be-obsolete technologies; energy-efficiency requirements; Parties' reporting and compliance<ref>{{Cite web |title=Summary report 23–29 October 2021 |url=https://enb.iisd.org/Montreal-Protocol-Ozone-MOP33-Vienna-Convention-COP12-summary |access-date=2025-08-27 |website=IISD Earth Negotiations Bulletin |language=en}}</ref><ref>{{Cite web |title=Post-Session Documents {{!}} Ozone Secretariat |url=https://ozone.unep.org/meetings/thirty-third-meeting-parties/post-session-documents |access-date=2025-08-27 |website=ozone.unep.org}}</ref> * 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<ref>{{Cite web |title=Post-session documents {{!}} Ozone Secretariat |url=https://ozone.unep.org/meetings/44th-meeting-open-ended-working-group-parties/post-session-documents |access-date=2025-08-27 |website=ozone.unep.org}}</ref> * 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<ref>{{Cite web |title=Summary report 31 October – 4 November 2022 |url=https://enb.iisd.org/montreal-protocol-meeting-parties-ozone-mop34-summary |access-date=2025-08-27 |website=IISD Earth Negotiations Bulletin |language=en}}</ref><ref>{{Cite web |title=Post-session documents {{!}} Ozone Secretariat |url=https://ozone.unep.org/meetings/thirty-fourth-meeting-parties/post-session-documents |access-date=2025-08-27 |website=ozone.unep.org}}</ref> * 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<ref>{{Cite web |title=Post-session documents {{!}} Ozone Secretariat |url=https://ozone.unep.org/meetings/45th-meeting-open-ended-working-group-parties/post-session-documents |access-date=2025-08-27 |website=ozone.unep.org}}</ref> * MOP 35 (2023): Decisions on MLF replenishment; feedstock uses of methyl bromide; import and export of prohibited cooling equipment (see entry on environmental dumping)<ref>{{Cite web |title=Summary report 22–27 October 2023 |url=https://enb.iisd.org/montreal-protocol-meeting-parties-ozone-mop35-summary |access-date=2025-08-27 |website=IISD Earth Negotiations Bulletin |language=en}}</ref><ref>{{Cite web |title=Post-session documents {{!}} Ozone Secretariat |url=https://ozone.unep.org/meetings/thirty-fifth-meeting-parties/post-session-documents |access-date=2025-08-27 |website=ozone.unep.org}}</ref> * 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<ref>{{Cite web |title=Summary report 8–12 July 2024 |url=https://enb.iisd.org/montreal-protocol-substances-deplete-ozone-layer-oewg46-summary |access-date=2025-08-27 |website=IISD Earth Negotiations Bulletin |language=en}}</ref><ref>{{Cite web |title=Post-session documents {{!}} Ozone Secretariat |url=https://ozone.unep.org/meetings/46th-meeting-open-ended-working-group-parties/post-session-documents |access-date=2025-08-27 |website=ozone.unep.org}}</ref> * 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.<ref>{{Cite web |title=Post-session documents {{!}} Ozone Secretariat |url=https://ozone.unep.org/meetings/thirty-sixth-meeting-parties/post-session-documents |access-date=2025-08-27 |website=ozone.unep.org}}</ref><ref>{{Cite web |title=Summary report 27 October – 1 November 2024 |url=https://enb.iisd.org/montreal-protocol-ozone-mop36-vienna-convention-cop13-summary |access-date=2025-08-27 |website=IISD Earth Negotiations Bulletin |language=en}}</ref>

==History== {{See also|Ozone depletion#Research History}}{{more citations needed section|date=September 2019}} 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.<ref>{{Cite web |title=How UCI saved the ozone layer – UC Irvine News |url=https://news.uci.edu/2023/01/11/how-uci-saved-the-ozone-layer/ |access-date=2025-08-26 |language=en-US}}</ref> 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 (O<sub>3</sub>) in the stratosphere.<ref>{{Cite journal|title=Stratospheric sink for chlorofluoromethanes: chlorine atom-catalysed destruction of ozone|url=https://www.nature.com/articles/249810a0|journal=Nature|date=June 1974 |issn=1476-4687|pages=810–812|volume=249|issue=5460|doi=10.1038/249810a0|language=en|first1=Mario J.|last1=Molina|first2=F. S.|last2=Rowland |bibcode=1974Natur.249..810M }}</ref><ref>{{Cite news |date=2022-11-09 |title=Research Profile - Mario Molina {{!}} Lindau Mediatheque |url=https://mediatheque.lindau-nobel.org/laureates/molina/research-profile |archive-url=http://web.archive.org/web/20251011040916/https://mediatheque.lindau-nobel.org/laureates/molina/research-profile |archive-date=2025-10-11 |access-date=2026-01-14 |work=Lindau Nobel Mediatheque |language=en-US}}</ref> In 1976, the U.S. National Academy of Sciences released a report that confirmed the scientific credibility of the ozone depletion hypothesis.<ref name="NAS1976">{{cite book | last = National Academy of Sciences | author-link = United States National Academy of Sciences | title = Halocarbons, effects on stratospheric ozone | year = 1976 | location = Washington, DC | url = https://nap.nationalacademies.org/read/19978 | isbn = 0-309-02532-X}}</ref>

In 1982, representatives from 24 countries met in Stockholm, Sweden to decide on a "Global Framework Convention for the Protection of the Ozone Layer."<ref>{{Cite book |last=Yoshida |first=Osamu |url=https://brill.com/view/title/10814 |title=The International Legal Régime for the Protection of the Stratospheric Ozone Layer: Second Revised Edition |date=2001-04-01 |publisher=Brill {{!}} Nijhoff |isbn=978-90-04-29087-7 |doi=10.1163/9789004290877_004}}</ref> The following year, a group of countries, including the United States, Canada, the Nordic Countries, and Switzerland, proposed a worldwide ban on "nonessential" uses of CFCs in spray cans.<ref name="Benedick 1989 43–50">{{Cite journal |last=Benedick |first=Richard Elliot |date=1989 |title=Ozone Diplomacy |url=https://www.jstor.org/stable/43309418 |journal=Issues in Science and Technology |volume=6 |issue=1 |pages=43–50 |jstor=43309418 |issn=0748-5492}}</ref>

In 1985, British Antarctic Survey scientists Joe Farman, Brian Gardiner and Jon Shanklin published results of abnormally low ozone concentrations above Halley Bay near the South Pole.<ref>{{Cite journal|title=Large losses of total ozone in Antarctica reveal seasonal ClOx/NOx interaction|url=https://www.nature.com/articles/315207a0|journal=Nature|date=May 1985|issn=1476-4687|pages=207–210|volume=315|issue=6016|doi=10.1038/315207a0|language=en|first1=J. C.|last1=Farman|first2=B. G.|last2=Gardiner|first3=J. D.|last3=Shanklin|url-access=subscription}}</ref> They speculated that this was connected to increased levels of CFCs in the atmosphere. This unforeseen phenomenon in the Antarctic, as well as NASA's scientific images of the ozone hole played an important role in the Montreal Protocol negotiations.<ref>{{cite journal | doi=10.1017/S000708742300002X | title=Satellite images as tools of visual diplomacy: NASA's ozone hole visualizations and the Montreal Protocol negotiations | year=2023 | last1=Grevsmühl | first1=Sebastian V. | last2=Briday | first2=Régis | journal=The British Journal for the History of Science | volume=56 | issue=2 | pages=247–267 | pmid=36776108 | s2cid=256825183 | doi-access=free }}</ref> The impact of these studies, the metaphor 'ozone hole', and the colorful visual representation in a time lapse animation proved shocking enough for negotiators in Montreal, Canada to take the issue seriously.<ref>Grundmann, Reiner, Transnational Environmental Policy: Reconstructing Ozone, London: Routledge, {{ISBN|0-415-22423-3}}</ref> thumb|TOMS satellite map showing the total ozone above the Antarctic region. Taken on 1 October 1983 (NASA). thumb|Parties subscribed to the Montreal Protocol by region (1987–2013) Also in 1985, 20 nations, including most major CFC producers, signed the Vienna Convention, which established a framework for negotiating international regulations on ozone-depleting substances.<ref>{{Cite web|url=https://ozone.unep.org/treaties/vienna-convention|website=ozone.unep.org|access-date=2020-04-22|title=The Vienna Convention for the Protection of the Ozone Layer &#124; Ozone Secretariat }}</ref> From the discovery of the ozone hole, it only took 18 months to reach a binding agreement in Montreal, Canada. Mostafa Kamal Tolba, the head of the UNEP at the time, was considered the "father of the Montreal Protocol" for his role in bringing the nations together for an agreement.<ref>{{Cite web |title=Dr. Mostafa Tolba, Father of Montreal Protocol, Dies at 93 - IGSD |date=29 March 2016 |url=https://www.igsd.org/dr-mostafa-tolba-father-of-montreal-protocol-dies-at-93/ |access-date=2023-09-28 |language=en-US}}</ref>

In 1986, an assessment spearheaded by NASA and sponsored by the United Nations Environment Program, the World Meteorological Organization, and various other organizations concluded that continued CFC emissions at the 1980 rate would "reduce global average ozone by about 9 percent by the latter half of the century." Based on these figures, the U.S. Environmental Protection Agency estimated that in the United States alone there could be "over 150 million new cases of skin cancer among people currently alive and born by the year 2075, resulting in over 3 million deaths."<ref name="Benedick 1989 43–50"/>

The CFC industry continued pushing back against regulation as late as 1986, when the Alliance for Responsible CFC Policy (an association representing the CFC industry founded by DuPont) <ref>{{Cite journal |last=Maxwell |first=James |last2=Briscoe |first2=Forrest |date=November 1997 |title=There's money in the air: the CFC ban and DuPont's regulatory strategy |url=https://doi.org/10.1002/(sici)1099-0836(199711)6:5<276::aid-bse123>3.0.co;2-a |journal=Business Strategy and the Environment |volume=6 |issue=5 |pages=276–286 |doi=10.1002/(sici)1099-0836(199711)6:5<276::aid-bse123>3.0.co;2-a |issn=0964-4733|url-access=subscription }}</ref>was still arguing that the science was too uncertain to justify any action. In 1987, DuPont testified before the US Congress that "We believe there is no imminent crisis that demands unilateral regulation."<ref name=Doyle1991>{{cite news|last1=Doyle|first1=Jack|title=DuPont's Disgraceful Deeds: The Environmental Record of E.I. DuPont de Nemour|url=http://www.multinationalmonitor.org/hyper/issues/1991/10/doyle.html|journal=The Multinational Monitor|volume=12|issue=10|access-date=8 September 2014|date=October 1991}}</ref> And even in March 1988, Du Pont Chair Richard E. Heckert would write in a letter to the United States Senate, "we will not produce a product unless it can be made, used, handled and disposed of safely and consistent with appropriate safety, health and environmental quality criteria. At the moment, scientific evidence does not point to the need for dramatic CFC emission reductions. There is no available measure of the contribution of CFCs to any observed ozone change..."<ref name=Greenpeace1997>{{cite web|title=Du Pont: A Case Study in the 3D Corporate Strategy|url=http://archive.greenpeace.org/ozone/greenfreeze/moral97/6dupont.html|publisher=Greenpeace|access-date=8 September 2014|archive-url=https://web.archive.org/web/20120406093303/http://archive.greenpeace.org/ozone/greenfreeze/moral97/6dupont.html|archive-date=2012-04-06|year=1997}}</ref>

In an unexpected policy change, however, the Alliance for Responsible CFC Policy issued a statement in 1986 declaring that "large future increases...in CFCs...would be unacceptable to future generations," and that it would be "inconsistent with [industry] goals...to ignore the potential for risk to future generations." Three months before the protocol negotiations began, U.S. industry announced its support for new international controls on CFCs.<ref name="Benedick 1989 43–50"/>

==Multilateral Fund==

The main objective of the ''Multilateral Fund for the Implementation of the Montreal Protocol'' is to assist developing country parties to the Montreal Protocol whose annual per capita consumption and production of ozone depleting substances (ODS) is less than 0.3&nbsp;kg to comply with the control measures of the Protocol. Currently, 147 of the 196 Parties to the Montreal Protocol meet these criteria (they are referred to as Article 5 countries).

It embodies the principle agreed at the United Nations Conference on Environment and Development in 1992 that countries have a common but differentiated responsibility to protect and manage the global commons.

The Fund is managed by an executive committee with an equal representation of seven industrialized and seven Article 5 countries, which are elected annually by a Meeting of the Parties. The Committee reports annually to the Meeting of the Parties on its operations. The work of the Multilateral Fund on the ground in developing countries is carried out by four Implementing Agencies, which have contractual agreements with the executive committee:<ref>{{cite book|title=Creating a real change for the environment|year=2007|publisher=Secretariat of the Multilateral Fund for the Implementation of the Montreal Protocol|url=http://www.multilateralfund.org/InformationandMedia/publications/default.aspx|archive-date=15 May 2012|access-date=10 July 2012|archive-url=https://web.archive.org/web/20120515105107/http://www.multilateralfund.org/InformationandMedia/publications/default.aspx|url-status=dead}}</ref>

* United Nations Environment Programme (UNEP), through its OzonAction Programme. * United Nations Development Programme (UNDP). * United Nations Industrial Development Organization (UNIDO). * World Bank.

Up to 20 percent of the contributions of contributing parties can also be delivered through their bilateral agencies in the form of eligible projects and activities.

The fund is replenished on a three-year basis by the donors. Pledges amount to US$3.1 billion over the period 1991 to 2005. Funds are used, for example, to finance the conversion of existing manufacturing processes, train personnel, pay royalties and patent rights on new technologies, and establish national ozone offices.

== Parties == As of October 2022, all Member States of the United Nations, the Cook Islands, Niue, the Holy See, the State of Palestine as well as the European Union have ratified the original Montreal Protocol,<ref>{{cite web|url=https://treaties.un.org/pages/ViewDetails.aspx?src=TREATY&mtdsg_no=XXVII-2-a&chapter=27&clang=_en|title=2. a Montreal Protocol on Substances that Deplete the Ozone Layer Montreal, 16 September 1987|publisher=United Nations|access-date=2022-10-02}}</ref> with the State of Palestine being the last party to ratify the agreement, bringing the total to 198. 197 of those parties (with the exception of the State of Palestine) have also ratified the London, Copenhagen, Montreal, and Beijing amendments.<ref name="ozone.unep.org"/>

== Effect == thumb|Ozone-depleting gas trends Since the Montreal Protocol came into effect, the atmospheric concentrations of the most important chlorofluorocarbons and related chlorinated hydrocarbons have either leveled off or decreased.<ref>{{cite web|url=http://www.al.noaa.gov/assessments/2002/Q&As16.pdf|title=Has the Montreal Protocol been successful in reducing ozone-depleting gases in the atmosphere?|archive-url=https://web.archive.org/web/20060614130414/http://www.al.noaa.gov/assessments/2002/Q%26As16.pdf|archive-date=14 June 2006}}</ref> Halon concentrations have continued to increase, as the halons presently stored in fire extinguishers are released, but their rate of increase has slowed and their abundances are expected to begin to decline by about 2020. Also, the concentration of the HCFCs increased drastically at least partly because of many uses (e.g. used as solvents or refrigerating agents) CFCs were substituted with HCFCs. <ref>{{Cite web |last=Team |first=GML Web |title=LOGOS - NOAA Global Monitoring Laboratory |url=https://gml.noaa.gov/hats/about/hcfc.html |access-date=2026-04-04 |website=gml.noaa.gov |language=en}}</ref>While there have been reports of attempts by individuals to circumvent the ban, e.g. by smuggling CFCs from undeveloped to developed nations, the overall level of compliance has been high. Statistical analysis from 2010 show a clear positive signal from the Montreal Protocol to the stratospheric ozone.<ref>{{cite journal|title=Evidence for the effectiveness of the Montreal Protocol to protect the ozone layer|journal=Atmospheric Chemistry and Physics |volume=10|issue=24|pages=12161–12171| date=22 December 2010 |doi=10.5194/acp-10-12161-2010|last1=Mäder|first1=J. A.|last2=Staehelin|first2=J.|last3=Peter|first3=T.|last4=Brunner|first4=D.|last5=Rieder|first5=H. E.|last6=Stahel|first6=W. A.|bibcode=2010ACP....1012161M |url=http://www.atmos-chem-phys.net/10/12161/2010/acp-10-12161-2010.html|doi-access=free|hdl=20.500.11850/27649|hdl-access=free}}</ref> In consequence, the Montreal Protocol has often been called the most successful international environmental agreement to date. In a 2001 report, NASA found the ozone thinning over Antarctica had remained the same thickness for the previous three years,<ref>{{cite web |url=http://www.gsfc.nasa.gov/topstory/20011016ozonelayer.html |title=Top Story – 2001 Antarctic Ozone Hole Similar in Size to Holes of Past Three Years, NOAA and NASA Report – October 16, 2001 |publisher=gsfc.nasa.gov |access-date=2010-09-16 |url-status=dead |archive-url=https://web.archive.org/web/20091231121817/http://www.gsfc.nasa.gov/topstory/20011016ozonelayer.html |archive-date=31 December 2009 }}</ref> however in 2003 the ozone hole grew to its second largest size.<ref>{{cite web |url=http://www.noaanews.noaa.gov/stories/s2099.htm |title=NOAA News Online (Story 2099) |publisher=noaanews.noaa.gov |access-date=2010-09-16 }}</ref> The 2006 scientific evaluation of the effects of the Montreal Protocol states, "The Montreal Protocol is working: There is clear evidence of a decrease in the atmospheric burden of ozone-depleting substances and some early signs of stratospheric ozone recovery."<ref>Scientific Assessment of Ozone Depletion: 2006, http://www.esrl.noaa.gov/csd/assessments/2006/report.html {{Webarchive|url=https://web.archive.org/web/20100329095225/http://www.esrl.noaa.gov/csd/assessments/2006/report.html |date=29 March 2010 }}</ref> However, a more recent study seems to point to a relative increase in CFCs due to an unknown source.<ref>{{Cite web | url=https://www.sciencealert.com/it-looks-like-someone-is-producing-an-internationally-banned-ozone-destroying-chemical-once-again | title=A Mystery Source is Producing Banned Ozone-Destroying Chemicals, Shocking Scientists| date=16 May 2018}}</ref>

The 2002 Scientific Assessment of Ozone Depletion predicted the ozone layer would return to 1980 levels by middle of the 21st century.<ref>{{Cite web |last=Laboratory (CSL) |first=NOAA Chemical Sciences |title=NOAA CSL: Scientific Assessment of Ozone Depletion: 2002 |url=https://csl.noaa.gov/assessments/ozone/2002/executivesummary.html |access-date=2026-03-31 |website=csl.noaa.gov |language=en}}</ref> In the 2022 assessment, this was delayed to 2066 for Antarctica, 2045 for the Arctic, and 2040 for most of the world.<ref name=":1" /> This is thought to be due to changes in calculation formulas as well as atmospheric changes.<ref>{{Cite journal |last1=Lickley |first1=Megan J. |last2=Daniel |first2=John S. |last3=McBride |first3=Laura A. |last4=Salawitch |first4=Ross J. |last5=Velders |first5=Guus J. M. |date=2024-11-27 |title=The return to 1980 stratospheric halogen levels: a moving target in ozone assessments from 2006 to 2022 |url=https://acp.copernicus.org/articles/24/13081/2024/ |journal=Atmospheric Chemistry and Physics |language=English |volume=24 |issue=22 |pages=13081–13099 |doi=10.5194/acp-24-13081-2024 |doi-access=free |bibcode=2024ACP....2413081L |issn=1680-7316}}</ref>

Reported in 1997, significant production of CFCs occurred in Russia for sale on the black market to the EU throughout the 90s. Related US production and consumption was enabled by fraudulent reporting due to poor enforcement mechanisms. Similar illegal markets for CFCs were detected in Taiwan, Korea, and Hong Kong.<ref>{{cite web|url=http://digitalcommons.law.uga.edu/cgi/viewcontent.cgi?article=1486&context=gjicl|title=The Black Market Trade in Chlorofluorocarbons: The Montreal Protocol Makes Banned Refrigerants a Hot Commodity|last=Landers|first=Fredrick Poole|access-date=4 September 2019|date=1997}}</ref>

The Montreal Protocol is also expected to have effects on human health. A 2015 report by the U.S. Environmental Protection Agency estimates that the protection of the ozone layer under the Protocol will prevent over 280 million cases of skin cancer, 1.5 million skin cancer deaths, and 45 million cataracts in the United States.<ref>Updating Ozone Calculations and Emissions Profiles for Use in the Atmospheric and Health Effects Framework Model http://www.epa.gov/ozone/science/effects/AHEF_2015_Update_Report-FINAL_508.pdf {{Webarchive|url=https://web.archive.org/web/20150417175954/http://www.epa.gov/ozone/science/effects/AHEF_2015_Update_Report-FINAL_508.pdf |date=17 April 2015 }}</ref>

However, the hydrochlorofluorocarbons, or HCFCs, and hydrofluorocarbons, or HFCs, contribute to anthropogenic global warming.<ref>Rishav Goyal, Matthew H England, Alex Sen Gupta, and Martin Jucker. "Reduction in surface climate change achieved by the 1987 Montreal Protocol" Environmental Research Letters 2019 14 (12) 124041; {{doi|10.1088/1748-9326/ab4874}}</ref> On a molecule-for-molecule basis, these compounds are up to 10,000 times more potent greenhouse gases than carbon dioxide. The Montreal Protocol currently calls for a complete phase-out of HCFCs by 2030, but does not place any restriction on HFCs. Since the CFCs themselves are equally powerful greenhouse gases<ref>{{Cite web |last=US EPA |first=OAR |date=2015-12-23 |title=Overview of Greenhouse Gases |url=https://www.epa.gov/ghgemissions/overview-greenhouse-gases |access-date=2026-04-04 |website=www.epa.gov |language=en}}</ref>, the mere substitution of HFCs for CFCs does not significantly increase the rate of anthropogenic climate change, but over time a steady increase in their use could increase the danger that human activity will change the climate.<ref>{{cite web |url=http://www.eia.doe.gov/oiaf/1605/ggrpt/other_gases.html |title=EIA – Emissions of the Greenhouse Gases in the United States 2005 |publisher=eia.doe.gov |access-date=2010-09-16 |url-status=dead |archive-url=https://web.archive.org/web/20110421074012/http://www.eia.doe.gov/oiaf/1605/ggrpt/other_gases.html |archive-date=21 April 2011 }}</ref>

Policy experts have advocated for increased efforts to link ozone protection efforts to climate protection efforts.<ref>Mario Molina, Durwood Zaelke, K. Madhava Sarma, Stephen O. Andersen, Veerabhadran Ramanathan, and Donald Kaniaru. "Reducing abrupt climate change risk using the Montreal Protocol and other regulatory actions to complement cuts in {{CO2}} emissions" PNAS 2009 106 (49) 20616-20621; {{doi|10.1073/pnas.0902568106}}</ref><ref>CS Norman, SJ DeCanio and L Fan. "The Montreal Protocol at 20: Ongoing opportunities for integration with climate protection." Global Environmental Change Volume 18, Issue 2, May 2008, Pages 330–340; {{doi|10.1016/j.gloenvcha.2008.03.003}}</ref><ref>UNEP press release, 2008 http://www.unep.org/Documents.Multilingual/Default.asp?DocumentID=593&ArticleID=6250&l=en&t=long {{Webarchive|url=https://web.archive.org/web/20101116011343/http://www.unep.org/Documents.Multilingual/Default.asp?DocumentID=593&ArticleID=6250&l=en&t=long |date=16 November 2010 }}</ref> Policy decisions in one arena affect the costs and effectiveness of environmental improvements in the other.

With the agreement in 2016 of the Kigali Amendment that phases down production and consumption of hydrofluorocarbons (HFCs), the Montreal Protocol became both an ozone and a climate treaty because HFCs are powerful greenhouse gases.<ref>{{Cite journal |last1=Velders |first1=Guus J. M. |last2=Fahey |first2=David W. |last3=Daniel |first3=John S. |last4=McFarland |first4=Mack |last5=Andersen |first5=Stephen O. |date=2009-07-07 |title=The large contribution of projected HFC emissions to future climate forcing |journal=Proceedings of the National Academy of Sciences |volume=106 |issue=27 |pages=10949–10954 |doi=10.1073/pnas.0902817106 |doi-access=free |pmc=2700150 |pmid=19549868 |bibcode=2009PNAS..10610949V }}</ref>

As of November 2025, the EU is on track to comply with HFC obligations set out in the Montreal protocol.<ref>{{Cite web |date=2025-11-11 |title=Hydrofluorocarbon phase out in Europe |url=https://www.eea.europa.eu/en/analysis/indicators/hydrofluorocarbon-phase-down-in-europe |access-date=2026-03-31 |website=www.eea.europa.eu |language=en}}</ref>

In comparison to other environmental treaties, effective burden-sharing and solution proposals mitigating regional conflicts of interest have been among the success factors for the ozone depletion challenge, where global regulation based on the Kyoto Protocol has failed to do so.<ref name="cass">[http://law.vanderbilt.edu/files/archive/Sunstein-2008.pdf Of Montreal and Kyoto: A Tale of Two Protocols] {{Webarchive|url=https://web.archive.org/web/20140826120056/http://law.vanderbilt.edu/files/archive/Sunstein-2008.pdf |date=26 August 2014 }} by Cass R. Sunstein 38 ELR 10566 8/2008</ref> In this case of the ozone depletion challenge, there was global regulation already being implemented before a scientific consensus was established. Also, overall public opinion was convinced of possible imminent risks.<ref name="par">[https://www.researchgate.net/publication/41184037_Climate_Change_and_Knowledge_Politics Environmental Politics Climate Change and Knowledge Politics] {{webarchive|url=https://web.archive.org/web/20140826115142/http://stsclimate.soc.ku.dk/papers/grundmannclimatechangeandknowledgepolitics.pdf|date=26 August 2014}} Reiner Grundmann, Vol. 16, No. 3, 414–432, June 2007</ref><ref name="RG">[http://www.mpifg.de/pu/mpifg_book/mpifg_bd_39.pdf Technische Problemlösung, Verhandeln und umfassende Problemlösung, (eng. technical trouble shooting, negotiating and generic problem solving capability)] {{Webarchive|url=https://web.archive.org/web/20160303233113/http://www.mpifg.de/pu/mpifg_book/mpifg_bd_39.pdf |date=3 March 2016 }} in Gesellschaftliche Komplexität und kollektive Handlungsfähigkeit (Societys complexity and collective ability to act), ed. Schimank, U. (2000). Frankfurt/Main: Campus, pp. 154–182 [http://pubman.mpdl.mpg.de/pubman/faces/viewItemFullPage.jsp;jsessionid=1F12495443EF6AC95BFF12F29F3C4829?itemId=escidoc%3A1235032%3A2&view=EXPORT book summary at the Max Planck Gesellschaft] {{Webarchive|url=https://web.archive.org/web/20141012202222/http://pubman.mpdl.mpg.de/pubman/faces/viewItemFullPage.jsp;jsessionid=1F12495443EF6AC95BFF12F29F3C4829?itemId=escidoc%3A1235032%3A2&view=EXPORT |date=12 October 2014 }}</ref>

=== Regional detections of non-compliance ===

In 2018, scientists monitoring the atmosphere following the 2010 phaseout date reported evidence of continuing industrial production of CFC-11, likely in eastern Asia, with detrimental global effects on the ozone layer.<ref>{{cite web|url=https://www.npr.org/sections/thetwo-way/2018/05/17/611984631/banned-ozone-depleting-chemical-is-still-being-produced-somewhere-scientists-say|title=Banned Ozone-Depleting Chemical Is Still Being Produced Somewhere, Scientists Say|publisher=NPR|date=17 May 2018|access-date=17 May 2018}}</ref><ref>{{cite journal|title=An unexpected and persistent increase in global emissions of ozone-depleting CFC-11|author=Stephen A. Montzka |display-authors=etal |journal=Nature|volume=557|issue=7705|pages=413–417|date=17 May 2018|doi=10.1038/s41586-018-0106-2|pmid=29769666 |bibcode=2018Natur.557..413M |hdl=1983/fd5eaf00-34b1-4689-9f23-410a54182b61 |s2cid=21705434 |url=https://research-information.bristol.ac.uk/files/155735096/318003_2_merged_1521470846.pdf}}</ref> A monitoring study detected fresh atmospheric releases of carbon tetrachloride from China's Shandong province, beginning sometime after 2012, and accounting for a large part of emissions exceeding global estimates under the Montreal Protocol.<ref>{{cite journal|author=M. F. Lunt|display-authors=etal|title=Continued Emissions of the Ozone-Depleting Substance Carbon Tetrachloride From Eastern Asia|journal=Geophysical Research Letters|volume = 45|issue=20|pages=11,423–11,430|doi=10.1029/2018GL079500|date=28 September 2018|pmid=33005064|pmc=7526663|bibcode=2018GeoRL..4511423L |doi-access=free}}</ref>

== 25th anniversary celebrations == The year 2012 marked the 25th anniversary of the signing of the Montreal Protocol. Accordingly, the Montreal Protocol community organized a range of celebrations at the national, regional and international levels to publicize its considerable success to date and to consider the work ahead for the future.<ref>{{cite web |url=http://ozone.unep.org/new_site/en/ozone_day_details.php |title=Ozone Secretariat 25th Anniversary web page |publisher=Ozone.unep.org |access-date=11 July 2012 |archive-url=https://web.archive.org/web/20120625195246/http://ozone.unep.org/new_site/en/ozone_day_details.php |archive-date=25 June 2012 |url-status=dead }}</ref> Among its accomplishments are: *The Montreal Protocol was the first international treaty to address a global environmental regulatory challenge; *the first to embrace the "precautionary principle" in its design for science-based policymaking; *the first treaty where independent experts on atmospheric science, environmental impacts, chemical technology, and economics, reported directly to parties, without edit or censorship, functioning under norms of professionalism, peer review, and respect; *the first to provide for national differences in responsibility and financial capacity to respond by establishing a multilateral fund for technology transfer; the first MEA with stringent reporting, trade, and binding chemical phase-out obligations for both developed and developing countries; and, *the first treaty with a financial mechanism managed democratically by an executive board with equal representation by developed and developing countries.<ref>Canan, Penelope and Nancy Reichman (2013), "The Montreal Protocol" in J. Britt Holbrook (Chief Editor) Ethics, Science, Technology, and Engineering: An International Resource, 2nd Edition, Thompson Learning. </ref>

Within 25 years of signing, parties to the MP celebrate significant milestones. Significantly, the world has phased-out 98% of the Ozone-Depleting Substances (ODS) contained in nearly 100 hazardous chemicals worldwide; every country is in compliance with stringent obligations; and, the MP has achieved the status of the first global regime with universal ratification; even the newest member state, South Sudan, ratified in 2013. UNEP received accolades for achieving global consensus that "demonstrates the world’s commitment to ozone protection, and more broadly, to global environmental protection".<ref>ozone.unep.org</ref>

== See also == {{portal|border=no|Environment|Ecology|Global warming|Politics|World}} * Action for Climate Empowerment * Carbon footprint * Copenhagen Accord * Net capacity factor * International Day for the Preservation of the Ozone Layer * Paris Agreement * R-134a * Section 608 * Vienna Conference (1985) *Fossil fuel phase-out *Phase-out of fossil fuel vehicles *Phase-out of gas boilers *Plastic bans

==References== {{reflist}} {{CIA World Factbook|year=2003}}<small>(referred to as Ozone Layer Protection)</small>

==Further reading== * Andersen, S. O. and K. M. Sarma. (2002). ''Protecting the Ozone Layer: the United Nations History, Earthscan Press''. London. {{ISBN?}} * Andersen, S. O., K. M. Sarma and K. N. Taddonio. (2007). ''Technology Transfer for the Ozone Layer: Lessons for Climate Change''. Earthscan Press, London. {{ISBN?}} * Benedick, Richard E. (1991). ''Ozone Diplomacy''. Harvard University Press. {{ISBN|0-674-65001-8}} (Ambassador Benedick was the Chief U.S. Negotiator at the meetings that resulted in the Protocol.) * Brodeur, Paul (1986). "Annals of Chemistry: In the Face of Doubt." ''The New Yorker'', 9 June 1986, pp.&nbsp;70–87. * Chasek, Pam, David Downie, and J.W. Brown (2013). G''lobal Environmental Politics'', 6th ed., Boulder: Westview Press. {{ISBN?}} * Dotto, Lydia and Harold Schiff (1978). ''The Ozone War''. New York: Doubleday (publisher). {{ISBN?}} * Downie, David (1993). "Comparative Public Policy of Ozone Layer Protection." ''Political Science'' (NZ) 45(2): (December): 186–197. * Downie, David (1995). "Road Map or False Trail: Evaluating the Precedence of the Ozone Regime as Model and Strategy for Global Climate Change," ''International Environmental Affairs'', 7(4):321–345 (Fall 1995). * Downie, David (1999). "The Power to Destroy: Understanding Stratospheric Ozone Politics as a Common Pool Resource Problem", in J. Barkin and G. Shambaugh (eds.) ''Anarchy and the Environment: The International Relations of Common Pool Resources''. Albany: State University of New York Press. {{ISBN?}} * David L. Downie (2012). "The Vienna Convention, Montreal Protocol and Global Policy to Protect Stratospheric Ozone", in P. Wexler et al. (eds.) ''Chemicals, Environment, Health: A Global Management Perspective''. Oxford: Taylor & Francis. {{ISBN?}} * Downie, David (2013) "Stratospheric Ozone Depletion." ''The Routledge Handbook of Global Environmental Politics''. New York: Routledge. {{ISBN?}} * Farman, J.C., B.G. Gardiner, and J.D. Shanklin (1985). "Large Losses of Total Ozone in Antarctica Reveal Seasonal {{chem|ClO|x}}/{{NOx}} Interaction." ''Nature'' 315: 207–210, 16 May 1985. * Gareau, Brian J. (2013). ''From Precaution to Profit: Contemporary Challenges to Environmental Protection in the Montreal Protocol''. New Haven & London: Yale University Press. {{ISBN|978-0300175264}} * Grundmann, Reiner. (2001). ''Transnational Environmental Policy: Reconstructing Ozone'', London: Routledge. {{ISBN|0-415-22423-3}} * Litfin, Karen T. (1994). ''Ozone Discourses''. Columbia University Press. {{ISBN|0-231-08137-5}} * Molina, Mario and F. Sherwood Rowland (1974). "Stratospheric Sink for Chlorofluoromethanes: Chlorine Atomic Catalyzed Destruction of Ozone." ''Nature'' 249: 810–812, 28 June 1974. * Morissette, P.M. (1989). "The evolution of policy responses to stratospheric ozone depletion." ''Natural Resources Journal'' 29: 793–820. * Parson, Edward (2003). ''Protecting the Ozone Layer: Science and Strategy''. Oxford: Oxford University Press. {{ISBN?}} * Roan, Sharon (1989). ''Ozone Crisis: The 15-Year Evolution of a Sudden Global Emergency''. New York, John Wiley and Sons {{ISBN?}} * United Nations Environmental Programme. (2012). ''[https://web.archive.org/web/20151121215638/http://new.unep.org/ozonaction/Portals/105/documents/publications/green-economy-report.pdf The Montreal Protocol and The Green Economy]''. * Velders, G. J. M., S. O. Andersen, J. S. Daniel, D. W. Fahey, and M. McFarland. (2007). ''[http://www.pnas.org/content/104/12/4814.full The Importance of the Montreal Protocol in Protecting the Climate]''. Proc. of the Natl. Acad. Of Sci., 104(12), 4814–4819, {{doi|10.1073/pnas.0610328104}}. * Velders, G. J. M., D. W. Fahey, J. S Daniel, M. McFarland, and S. O. Andersen. (2009). ''[http://www.pnas.org/content/early/2009/06/19/0902817106.full.pdf+html?with-ds=yes The Large Contribution of Projected HFC Emissions to Future Climate Forcing]''. Proc. of the Natl. Acad. Of Sci., 106(27), {{doi|10.1073/pnas.0902817106}}. * Velders, G. J. M., A. R. Ravishankara, M. K. Miller, M. J. Molina, J. Alcamo, J. S. Daniel, D. W. Fahey, S. A. Montzka, and S. Reimann. (2012). ''[https://www.science.org/doi/10.1126/science.1216414 Preserving Montreal Protocol Climate Benefits by Limiting HFCs]''. Science, 335(6071), 922–923, {{doi|10.1126/science.1216414}}.

== External links == *[http://www.multilateralfund.org/ Multilateral Fund for the Implementation of the Montreal Protocol] *[https://web.archive.org/web/20130602153542/http://ozone.unep.org/new_site/en/montreal_protocol.php The Montreal Protocol] *[https://web.archive.org/web/20140812203449/http://ozone.unep.org/new_site/en/vienna_convention.php The Vienna Convention] *[https://web.archive.org/web/20130419060849/http://ozone.unep.org/new_site/en/Treaties/treaties_decisions-hb.php?art_id=59,60,61,62,63 Ozone-Depleting Substances (ODS) Controlled Under the Montreal Protocol] *[https://web.archive.org/web/20071011123227/http://www.epa.gov/ozone/strathome.html U.S. EPA Ozone Layer Protection Information Home Page] *[http://www.unep.fr/ozonaction/montrealprotocolwhoswho/ The Montreal Protocol Who's Who] {{Webarchive|url=https://web.archive.org/web/20100531033513/http://www.unep.fr/ozonaction/montrealprotocolwhoswho/ |date=31 May 2010 }} *[https://web.archive.org/web/20150919203230/http://www.ncseonline.org/cfc-ozone-puzzle-environmental-science-global-arena-2000-chafee-memorial-lecture] by F.Sherwood Rowland and Mario J.Molina *[http://www.esrl.noaa.gov/csd/assessments/ozone/2002/qandas16.pdf Has the Montreal Protocol been successful in reducing ozone-depleting gases in the atmosphere? ](NOAA Aeronomy Lab) *[http://www.cei.org/gencon/025,01184.cfm Doomsday Déjà vu: Ozone Depletion's Lessons for Global Warming] {{Webarchive|url=https://web.archive.org/web/20090910000608/http://cei.org/gencon/025,01184.cfm |date=10 September 2009 }} by [https://web.archive.org/web/20051213041936/http://www.cei.org/dyn/view_Expert.cfm?Expert=6 Ben Lieberman] *[http://www.eia-international.org/media?cat1=196&cat2=236 EIA reports]: Reports on illegal trade and solutions. * [http://legal.un.org/avl/ha/vcpol/vcpol.html Introductory note by Edith Brown Weiss, procedural history note and audiovisual material] on the ''Montreal Protocol on Substances that Deplete the Ozone Layer'' in the [http://legal.un.org/avl/historicarchives.html Historic Archives of the United Nations Audiovisual Library of International Law] * [http://www.green-cooling-initiative.org/ Green Cooling Initiative] * [http://www.green-cooling-initiative.org/ Green Cooling Initiative on alternative natural refrigerants cooling technologies]

{{Presidency of Ronald Reagan}} {{Pollution}}

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