|Signed||16 September 1987|
|Effective||1 January 1989 if 11 states have ratified by then.|
|Condition||ratification by 20 states|
|Ratifiers||197 (all United Nations members, as well as Niue, the Cook Islands, the Holy See and the European Union)|
|Depositary||Secretary-General of the United Nations|
|Languages||Arabic, Chinese, English, French, Russian and Spanish.|
The Montreal Protocol on Substances that Deplete the Ozone Layer (a protocol to the Vienna Convention for the Protection of the Ozone Layer) is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances believed to be responsible for ozone depletion. The treaty was opened for signature on September 16, 1987, and entered into force on January 1, 1989, followed by a first meeting in Helsinki, May 1989. Since then, it has undergone seven revisions, in 1990 (London), 1991 (Nairobi), 1992 (Copenhagen), 1993 (Bangkok), 1995 (Vienna), 1997 (Montreal), and 1999 (Beijing). It is believed that if the international agreement is adhered to, the ozone layer is expected to recover by 2050. Due to its widespread adoption and implementation it has been hailed as an example of exceptional international co-operation, with Kofi Annan quoted as saying that "perhaps the single most successful international agreement to date has been the Montreal Protocol". The two ozone treaties have been ratified by 197 states and the European Union making them the most widely ratified treaties in United Nations history.
Terms and purposes 
The treaty is structured around several groups of halogenated hydrocarbons that have been shown to play a role in ozone depletion. All of these ozone depleting substances contain either chlorine or bromine (substances containing only fluorine do not harm the ozone layer). For a table of ozone-depleting substances see: 
For each group, including group ST, the treaty provides a timetable on which the production of those substances must be phased out and eventually eliminated.
Chlorofluorocarbons (CFCs) Phase-out Management Plan 
The stated purpose of the treaty is that the signatory states "Recognizing that worldwide emissions of certain substances, including ST, 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, including ST 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.
There was a slower phase-out (to zero by 2010) of other substances (halon 1211, 1301, 2402; CFCs 13, 111, 112, etc.) and some chemicals were given individual attention (Carbon tetrachloride; 1,1,1-trichloroethane). The phasing-out of the less active HCFCs only began in 1996 and will go on until a complete phasing-out is achieved by 2030.
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 year 2013 as the time to freeze the consumption and production of HCFCs. They also agreed to start reducing its consumption and production in 2015. The time of freezing and reducing HCFCs is then known as 2013/2015.
The HCFCs are transitional CFCs replacements, used as refrigerants, solvents, blowing agents for plastic foam manufacture, and fire extinguishers. In term of Ozone Depleting Potential (ODP), in comparison to CFCs that have ODP 0.6 – 1.0, these HCFCs have less ODP, i.e. 0.01 – 0.5. Whereas in term of Global Warming Potential (GWP), in comparison to CFCs that have GWP 4,680 – 10,720, HCFCs have less GWP, i.e. 76 – 2,270.
There are a few exceptions for "essential uses", where no acceptable substitutes have been found (for example, in the past metered dose inhalers commonly used to treat asthma and other respiratory problems were exempt, but no longer as of 12/31/11.) or Halon fire suppression systems used in submarines and aircraft (but not in general industry).
The substances in Group I of Annex A are:
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.
Several reports have been published by various governmental and non-governmental organizations to present alternatives to the ozone depleting substances, since the substances have been used in various technical sectors, like in refrigerating, agriculture, energy production, and laboratory measurements
Hydrofluorocarbons (HFCs) 
Produced mostly in developed countries, HFCs replaced chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), that were phased out under the Montreal Protocol on Substances that Deplete the Ozone Layer. HFCs pose no harm to the ozone layer because, unlike CFCs and HCFCs, they do not contain chlorine that depletes the ozone layer. But it has been established that HFCs are not innocuous either. They are super-greenhouse gases with an extremely high global warming potential. This means they are capable of trapping enormous amounts of infrared radiations in the atmosphere and can cause a greenhouse effect a thousand times stronger than carbon dioxide. It has been four years since the issue of bringing HFCs under the Protocol’s ambit was raised. Developed countries say that since the rise in the emission of super-greenhouse gases is a consequence of the phasing out of CFCs and HCFCs under the Montreal Protocol, the same agreement should monitor them. Developing countries like India, China and Brazil, however, say that the emission and regulation of greenhouse gases fall under the purview of the United Nations Framework Convention on Climate Change (UNFCCC) and HFCs already figure in the basket of six greenhouse gases under the Kyoto Protocol. Developed countries following the Kyoto Protocol report their HFC emission data to UNFCCC; parties to the Montreal Protocol have no such obligation. At the root of this argument is a doubt. Developing countries are apprehensive about the high cost of transition from HFCs to a safer option.
In 1973, the chemists Frank Sherwood Rowland and Mario Molina, who were then 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 got up into the middle of the stratosphere where they would finally (after an average of 50–100 years for two common CFCs) be broken down by ultraviolet radiation releasing 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. Their argument was based upon an analogy to contemporary work by Paul J. Crutzen and Harold Johnston, which had shown that nitric oxide (NO) could catalyze the destruction of ozone. (Several other scientists, including Ralph Cicerone, Richard Stolarski, Michael McElroy, and Steven Wofsy had independently proposed that chlorine could catalyze ozone loss, but none had realized that CFCs were a potentially large source of chlorine.) Crutzen, Molina and Rowland were awarded the 1995 Nobel Prize for Chemistry for their work on this problem.
The environmental consequence of this discovery was that, since stratospheric ozone absorbs most of the ultraviolet-B (UV-B) radiation reaching the surface of the planet, depletion of the ozone layer by CFCs would lead to an in increase in UV-B radiation at the surface, resulting in an increase in skin cancer and other impacts such as damage to crops and to marine phytoplankton.
But the Rowland-Molina hypothesis was strongly disputed by representatives of the aerosol and halocarbon industries. The chair of the board of DuPont was quoted as saying that ozone depletion theory is "a science fiction tale...a load of rubbish...utter nonsense". Robert Abplanalp, the president of Precision Valve Corporation (and inventor of the first practical aerosol spray can valve), wrote to the Chancellor of UC Irvine to complain about Rowland's public statements (Roan, p. 56.)
After publishing their pivotal paper in June 1974, Rowland and Molina testified at a hearing before the U.S. House of Representatives in December 1974. As a result significant funding was made available to study various aspects of the problem and to confirm the initial findings. In 1976, the U.S. National Academy of Sciences (NAS) released a report that confirmed the scientific credibility of the ozone depletion hypothesis. NAS continued to publish assessments of related science for the next decade.
Then, in 1985, British Antarctic Survey scientists Farman, Gardiner and Shanklin published results of abnormally low ozone concentrations above Halley Bay near the South Pole. They speculated that this was connected to increased levels of CFCs in the atmosphere. It took several other attempts to establish the Antarctic losses as real and significant, especially after NASA had retrieved matching data from its satellite recordings. The impact of these studies, the metaphor 'ozone hole', and the colourful visual representation in a time lapse animation proved shocking enough for negotiators in Montreal to take the issue seriously.
Also in 1985, 20 nations, including most of the major CFC producers, signed the Vienna Convention, which established a framework for negotiating international regulations on ozone-depleting substances. After the discovery of the ozone hole it only took 18 months to reach a binding agreement in Montreal.
But the CFC industry did not give up that easily. As late as 1986, the Alliance for Responsible CFC Policy (an association representing the CFC industry founded by DuPont) was still arguing that the science was too uncertain to justify any action. In 1987, DuPont testified before the US Congress that "we believe that there is no immediate crisis that demands unilateral regulation."
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 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:
- United Nations Environment Programme (UNEP), through the UNEP DTIE 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$ 2.1 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.
As of December 29, 2012, all countries in the United Nations, the Cook Islands, Holy See, Niue and the supranational European Union have ratified the original Montreal Protocol (see external link below), South Sudan being the last country to ratify the agreement, bringing the total to 197. These countries have also ratified the first three amendments. The last two amendments had as of 26 February 2012 not been ratified by 3 and 9 members respectively.
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. 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 for many uses (e.g. used as solvents or refrigerating agents) CFCs were substituted with HCFCs. 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. 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, however in 2003 the ozone hole grew to its second largest size. The most recent (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."
Unfortunately, the hydrochlorofluorocarbons, or HCFCs, and hydrofluorocarbons, or HFCs, are now thought to contribute to anthropogenic global warming. 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, the mere substitution of HFCs for CFCs does not significantly increase the rate of anthropogenic global warming, but over time a steady increase in their use could increase the danger that human activity will change the climate.
Policy experts have advocated for increased efforts to link ozone protection efforts to climate protection efforts. Policy decisions in one arena affect the costs and effectiveness of environmental improvements in the other.
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. 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.
Within 25 years of signing, Parties to the MP celebrate significant milestones; however, the job is not yet done and the current moment could not be more pivotal for accomplishing its vital mission. 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”.
See also 
- Speth, J. G. 2004. Red Sky at Morning: America and the Crisis of the Global Environment New Haven: Yale University Press, pp 95.
- The Ozone Hole-The Montreal Protocol on Substances that Deplete the Ozone Layer
- UNEP press release: "South Sudan Joins Montreal Protocol and Commits to Phasing Out Ozone-Damaging Substances".
- The full terms are available from http://ozone.unep.org/Publications/MP_Handbook/Section_1.1_The_Montreal_Protocol/.
- Exemption Information - The Ozone Secretariat Web Site
- Use of ozone depleting substances in laboratories. TemaNord 2003:516. http://www.norden.org/pub/ebook/2003-516.pdf
- The Technical and Economic Feasibility of Replacing Methyl Bromide in Developing Countries. Friends of the Earth, Washington, 173 pp, 1996
- Guidance on the DOE Facility Phaseout of Ozone-Depleting Substances. 1995. http://homer.ornl.gov/nuclearsafety/nsea/oepa/guidance/ozone/phaseout.pdf
- Down To Earth: Climate of irrationality
- National Academy of Sciences (1976). Halocarbons, effects on stratospheric ozone. Washington, DC.
- Grundmann, Reiner, Transnational Envionmental Policy: Reconstructing Ozone, London: Routledge, ISBN 0-415-22423-3
- Creating a real change for the environment. Secretariat of the Multilateral Fund for the Implementation of the Montreal Protocol. 2007.
- "Top Story - 2001 Antarctic Ozone Hole Similar in Size to Holes of Past Three Years, NOAA and NASA Report - October 16, 2001". www.gsfc.nasa.gov. Retrieved 2010-09-16.
- "NOAA News Online (Story 2099)". www.noaanews.noaa.gov. Retrieved 2010-09-16.
- Scientific Assessment of Ozone Depletion: 2006, http://www.esrl.noaa.gov/csd/assessments/2006/report.html
- "EIA - Emissions of the Greenhouse Gases in the United States 2005". www.eia.doe.gov. Retrieved 2010-09-16.
- 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
- 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
- UNEP press release, 2008 http://www.unep.org/Documents.Multilingual/Default.asp?DocumentID=593&ArticleID=6250&l=en&t=long
- Ozone Secretariat 25th Anniversary web page
- Canan, Penelope and Nancy Reichman (2013, forthcoming), "The Montreal Protocol" in J. Britt Holbrook (Chief Editor) Ethics, Science, Technology, and Engineering: An International Resource, 2nd Edition, Thompson Learning.
Further reading 
- Andersen, S. O. and K. M. Sarma. (2002). Protecting the Ozone Layer: the United Nations History, Earthscan Press. London.
- Andersen, S. O., K. M. Sarma and K. N. Taddonio. (2007). Technology Transfer for the Ozone Layer: Lessons for Climate Change. Earthscan Press, London.
- 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, June 9, 1986, pp. 70–87.
- Chasek, Pam, David Downie, and J.W. Brown (2013 - forthcoming). Global Environmental Politics, 6th Edition, Boulder: Westview Press.
- Dotto, Lydia and Harold Schiff (1978). The Ozone War. New York: Double Day.
- 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.
- 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.
- Downie, David (2013) “Stratospheric Ozone Depletion.” The Routledge Handbook of Global Environmental Politics. New York: Routledge.
- Farman, J.C., B.G. Gardiner, and J.D. Shanklin (1985). "Large Losses of Total Ozone in Antarctica Reveal Seasonal ClOx/NOx Interaction." Nature 315: 207-210, 16 May 1985.
- 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: 810-12, 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.
- Roan, Sharon (1989). Ozone Crisis: The 15-Year Evolution of a Sudden Global Emergency. New York, John Wiley and Sons
- United Nations Environmental Programme. (2012). The Montreal Protocol and The Green Economy.
- Velders, G. J. M., S. O. Andersen, J. S. Daniel, D. W. Fahey, and M. McFarland. (2007). 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). The Large Contribution of Projected HFC Emissions to Future Climate Forcing. Proc. of the Natl. Acad. Of Sci., 106(27), doi:10.1073/pnas.090281716.
- 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). Preserving Montreal Protocol Climate Benefits by Limiting HFCs. Science, 335(6071), 922-923, doi:10.1126/science.1216414.
- The Ozone Secretariat
- Multilateral Fund for the Implementation of the Montreal Protocol
- Status of Ratification
- The Montreal Protocol
- The Vienna Convention
- Ozone-Depleting Substances (ODS) Controlled Under the Montreal Protocol
- U.S. EPA Ozone Layer Protection Information Home Page
- The Montreal Protocol Who's Who
-  by F.Sherwood Rowland and Mario J.Molina
- Has the Montreal Protocol been successful in reducing ozone-depleting gases in the atmosphere? (NOAA Aeronomy Lab)
- Doomsday Déjà vu: Ozone Depletion's Lessons for Global Warming by Ben Lieberman
- EIA reports: Reports on illegal trade and solutions.
- 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 Historic Archives of the United Nations Audiovisual Library of International Law