Montreal Protocol

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The Montreal Protocol on Substances that Deplete the Ozone Layer (MP) of 1987 is an international agreement to protect the stratospheric ozone layer from harmful synthetic chemical compounds. The targets of the MP are synthetic chemical substances that destroy an upper level protective ozone layer of the Earth and whose destructive behavior persists over decades if not centuries, depending on the chemical compound. The MP is considered an exemplary case of science-based policy making, adroit diplomacy, innovative treaty language, and regulatory collaboration, and is the most successfully implemented global environmental treaty in history. It is also the best example to date of global action based on the precautionary principle.

The Issue and Efforts Leading to the Montreal Protocol

Ozone is a bluish gas, harmful to breathe, that is composed of three atoms of oxygen. Nearly 90 percent of the planetary ozone is in the stratosphere, an atmospheric region above the troposphere extending from about 10 to 50 kilometers in altitude. In the 1930s, scientists Dorothy Fisk and Charles Abbott discovered how to measure atmospheric ozone, and described the critical role an ozone layer plays as a global sunscreen. Stratospheric ozone absorbs a band of ultraviolet radiation (UVb), preventing most of it from reaching the ground where it is particularly harmful to living organisms (causing skin cancer and cataracts, interrupting food chains, and more).

Chlorofluorocarbons (CFCs), now recognized as ozone depleting substances (ODS), were hailed for being safe, friendly, and widely applicable when first invented about the same time that the benefits of the ozone layer were discovered. Besides their original application in refrigeration—where they were both safer and more efficient—CFCs were manufactured for an extremely wide variety of uses: flexible urethane foams (for carpeting, furniture, and automobile seats); rigid polyurethane foams (as insulation for buildings and refrigeration units); blowing agents in non-urethane foams (polyurethane sheet products, foam trays, fast-food wrappers); and refrigerants in automobile air conditioners, and industrial and commercial air conditioners known as chillers. CFCs became an important solvent for the electronics and aerospace industries as a cleaning agent for circuit boards and scientific instruments. Halons, another set of halogenated hydrocarbons, were widely used as flame suppressants in firefighting. Carbon tetrachloride, methylene chloride, and the agricultural chemical methyl bromide used as a soil fumigant and to protect stored agricultural products from pest-related deterioration, are implicated as well.

In the 1970s natural scientists (notably, Richard Stolarski, Ralph Cicerone, Sherwood Rowland, and Mario Molina) questioned whether these chemical compounds were benign in the stratosphere. When CFCs reach the stratosphere, ultra-violet radiation causes them to decompose releasing a chlorine atom that in turn destroys ozone molecules. They concluded that a single chlorine atom released in the stratosphere could eliminate thousands of ozone molecules through a catalytic chain reaction; that this reaction would continue for the life of the chemicals (40–150 years); and that CFC concentrations in the ozone layer could be expected to reach one to thirty times their current levels with disastrous consequences for the integrity of the ozone layer.

For the next ten years, debates over the science of ozone depletion raged, reflecting different industrial, political, and scientific worldviews and the symbolic resources brought to bear on the issue (Dotto 1978).

Much of the early empirical evidence of a "hole" in the stratospheric ozone layer was discounted by scientists who simply assumed that the extremely low Dobson instrument measurements were due to technical malfunctions. Indeed, the 1982 ozone measurement devices aboard the Nimbus 7 satellite had been programmed to flag low values as erroneous (Gribbin 1988). By the mid-1980s, however, scientists such as Shigeru Chubachi and Susan Solomon provided empirical evidence of stratospheric ozone depletion (Andersen and Sarma 2003). Consensus that an ozone hole was swiftly developing left open to debate whether the hole was caused by nature or by invented chemicals. Nevertheless, and importantly, even in the face of continuing uncertainty, the world moved from demands for more research to demands for precautionary regulation in a relatively short period of time.

In 1985, under the auspices of the United Nations Environment Programme (UNEP), Executive Director Mostafa Tolba led Australia, Canada, Finland, Germany, New Zealand, Norway, and the United States to adopt the Vienna Convention (VC). This was the first official version of international understandings and responsibilities regarding the protection of the stratospheric ozone layer. The MP, signed in September 1987, followed (Benedick 1991). By 2003, 184 nations had ratified the MP.

Implementation and Evolution of the Montreal Protocol

Parties to the MP agreed to use national consumption/production figures as a baseline from which to measure targets for phaseout, permitting flexibility so that each nation could determine how best to meet its national phaseout commitment. Article 6 established periodic reviews by scientific and technical experts so that the treaty could be adjusted with the benefit of fast-paced developments in science and technology. With amendments of the MP, the twin principle of differentiated responsibility/capability was adopted. Funds, expertise, and technology transfer supported developing countries that were not major contributors to the problem and whose domestic economic priorities were not in line with phaseout. (Article 5 lists 136 such nations in 2003.) The Global Environment Facility took responsibility for helping Countries-With-Economies-in-Transition (high ODS, economically troubled), typically members of the former Soviet Union.

Originally the treaty committed parties to reduce, by 1996, the use of CFCs by 50 percent, using their national 1986 baseline values. Failure to sign the treaty imposed import/export restrictions that encouraged wide participation, especially given that total, worldwide phaseout of the harmful substances meant that non-parties without production capability would not have access to supplies. This also prevented companies seeking to avoid controls on ODS from moving their production facilities to non-parties and exporting back into the countries controlled by the MP (Brack 1996).

By the time the treaty went into force on January 1, 1989, there was already a strong push for amending it, as anticipated. In 1990 the London Amendments provided for a total ban of CFCs by the end of the twentieth century, added other ODS to the list of controlled substances, created the Multilateral Fund (MLFund) to help developing countries phase out, instituted a ten-year grace period for developing country compliance, mandated technology transfer from rich countries, and reclassified hydrofluorcarbons (HCFCs) as transitional substances. The Copenhagen Amendments (1992) accelerated the compliance schedule, confirmed the MLFund permanently, and suggested new compounds for the control list, notably HCFCs and methyl bromide. Subsequent adjustments (Montreal 1997, Beijing 1999) replenished the MLFund and tightened control measures.

Administratively the treaty established the MP Secretariat (Nairobi) with K. M. Sarma as the first Executive Secretary and, after 1990, the MLFund Secretariat (Montreal), first headed by Omar El-Arini. The MLFund Executive Committee is composed of equal numbers of developed and developing countries. Four United Nations agencies support the phaseout through activities such as training, information sharing, institutional strengthening, conferences, and consultant services. Each Article 5 country has established a National Ozone Unit; these are strengthened by regional networking activities of the UNEP.

Three autonomous advisory panels—in Science, Environmental Impacts, and Technology and Economic Assessment (TEAP)—report directly to the parties. These volunteer expert review panels are the primary source of the confidence with which the parties have frequently amended the treaty in light of new, credible science and technology.

Over the first decade of the MP implementation, the TEAP, under the collaborative leadership of Stephen O. Andersen and Lambert Kuijpers, rose to preeminence as the worldwide authority on technically credible, economically possible options for speedy phaseout. Other than the Economic Options Committee, the TEAP was organized by industrial sector, and includes divisions such as the Technical Option Committee (TOC) for aerosols, foams, halons, methyl bromide, refrigeration, and solvents. The TEAP found and created new product designs, innovative practices, and industry-wide alterations in production processes that were harmful to the ozone layer.

The TEAP was built on the principle of dynamic collaboration across sciences, technologies, industries, governmental ministries, and citizen groups from around the world. Industries from Canada, Brazil, China, Germany, India, Japan, the Netherlands, Sweden, the United Kingdom, and the United States, among others, contributed more than 50 percent of the approximately 700 TEAP members.

TEAP experts were not required to share the epistemology of precaution. However they were expected to work with disregard of national or industrial interests and toward global solutions with a can-do spirit. They did this by developing strong social bonds of trust and respect (a tight community) and by forging collaborative norms of problem solving, boundary spanning, and information sharing. The effective regulatory community that emerged from the TEAP—largely the result of collaborative leadership as well as linkages to broader constituencies in government, industry, and the academy—became valuable and necessary resources in the creation and transfer of knowledge so essential to MP success (Canan and Reichman 2002).

The one area where phaseout has lagged is addressing the issue of methyl bromide, in which commitment to planetary concerns has not overridden industrial interests and national politics. Nominations for Critical Use Exemptions for methyl bromide have used criteria that differ from the criteria for other ODS. For other ODS, an essential use is defined as one that "is necessary for the health, safety or is critical for the functioning of society (encompassing cultural and intellectual aspects)" (Decision IV/25 of the Parties, cited in DeCanio and Norman, 2003). An oft-cited example was the exemption for CFC use for Metered Dose Inhalers (MDIs) having life-and-death criticality. However the MP allows nominations for critical use exemptions to the methyl bromide phaseout based on claims that alternatives are not economically feasible or that the phaseout would cause significant market disruption. As a result, some parties have requested exemptions for a range of methyl bromide applications, including tobacco, pet food, flowers, and golf courses (DeCanio and Norman 2003).

Despite the tremendous progress that has been made accelerating phaseout dates, banning additional chemicals, and identifying, creating, and adopting alternative technologies, the long life of ODS means that restoring the earth's protective stratospheric ozone layer will remain a serious challenge throughout the twenty-first century.


SEE ALSO Global Climate Change;International Relations.


Andersen, Stephen O., and K. M. Sarma. (2003). Protecting the Ozone Layer: The United Nations History. London: Earthscan. An authoritative and exhaustively documented history of the science and diplomacy that led to the Montreal Protocol; contains a detailed account of the contribution of business, industry, and government to develop environmentally sound alternative technologies to restore the ozone layer. Provides a careful record of the role of the media and non-governmental organizations in evolving the global response to the destruction of stratospheric ozone. It is the official UN history of the Montreal Protocol.

Benedick, Richard. (1991). Ozone Diplomacy: New Directions in Safeguarding the Planet. Cambridge, MA: Harvard University Press. Provides a detailed account from the perspective of the senior U.S. negotiator of the Montreal Protocol. Features interpretations of the bargaining motivation and stratagems of other countries. Stimulated many others to tell the story from their own perspective.

Brack, Duncan. (1996). International Trade and the Montreal Protocol. London: Earthscan. Covers the role of trade as a governing principle for international agreements and how variable national economic positions view trade sanctions as impetus for participation and compliance.

Canan, Penelope, and Nancy Reichman. (2002). Ozone Connections: Expert Networks in Global Environmental Governance. Sheffield, UK: Greenleaf. A sociological analysis of the extent and effectiveness of a small number of experts, organized in communities of practice, were instrumental in protecting the ozone layer. Looking systematically at the connection between technology, global environmental policy, and the social connections of experts, the authors focus on the Technology and Economic Assessment Panel of the Montreal Protocol. By combining formal network analysis, biographical interviews and participant observation, they demonstrate that treaty implementation relies on social relations, trust and the collaborative leadership of institutional entrepreneurs.

Dotto, Lydia, and Harold Schiff. (1978). The Ozone War. New York: Doubleday and Company. The most comprehensive early account of conflict among scientists, citizens, industry, and political activists. It was published during the decade when UENP and national environmental ministries were created and environmental law was invented, but long before there was much hope of stratospheric ozone protection.

Gribbin, John R. (1988). The Hole in the Sky: Man's Threat to the Ozone Layer. New York: Bantam. Documents the triumph of science and diplomacy in securing the Montreal Protocol.


DeCanio, S. J., and C. S. Norman. "Economic Aspects of Nominations for Critical Use of Methyl Bromide Under Terms of The Montreal Protocol." Included in UNEP Report of the Technology and Economic Assessment Panel, May 2003 Progress Report. Available at A sophisticated analysis of the economics of critical uses of ODS revealing the politics of changing definitions risk.

Montreal Protocol

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Montreal Protocol


The Montreal Protocol on Substances that Deplete the Ozone Layer is an international environmental treaty aimed at reducing and phasing out the production of ozone-depleting substances (ODS), including chlorofluorocarbons (CFCs). Adopted in 1987, the Montreal Protocol was the first binding international multilateral environmental agreement. The discovery of a “hole” Earth’s protective stratospheric ozone layer in the 1980s prompted the international community to act quickly to reduce ODS. The widespread international support and the effectiveness of the Montreal Protocol made it one of the most successful international environmental treaties.

Historical Background and Scientific Foundations

The ozone layer is a relatively concentrated area of ozone (O3) in the lower portion of the stratosphere that absorbs most of the harmful ultraviolet (UV) radiation from the sun. Ultraviolet radiation, particularly UV-B, causes skin cancer and harms oxygen-producing plants and phytoplankton. Ozone-depleting substances (ODS) are chemical compounds that destroy ozone molecules. All ODS are haloalkanes, a group of chemical compounds comprised of alkenes (a type of hydrocarbon) combined with one or more halogens, typically chlorine or fluorine. Haloalkanes were widely used in industry as aerosol propellants, refrigerants, solvents, and fire extinguishing agents.

Chlorofluorocarbons (CFCs) are the most widely known group of haloalkanes that destroy ozone. CFCs are a group of chemical compounds consisting of two halogens, chlorine and fluorine, and carbon. CFCs, which do not contain hydrogen, remain in the atmosphere for 50 to 100 years before degrading. A single CFC molecule typically degrades 10,000 ozone molecules but can degrade millions of ozone molecules.

Unlike CFCs, hydrochlorofluorocarbons (HCFCs) do contain hydrogen. HCFCs are less destructive to the ozone layer than CFCs. Therefore, HCFCs are commonly used to replace CFCs in industrial uses. Hydrofluorocarbons (HFCs) are a group of haloalkanes comprised of hydrogen, carbon, and fluorine. HFCs do not contain chlorine. HFCs do not destroy ozone and, therefore, are not regulated under the Montreal Protocol.

In addition to depleting the ozone layer, CFCs and HCFCs are powerful greenhouse gases that contribute to global climate change. One metric ton of CFCs is the equivalent of 5,000-8,000 metric tons of carbon dioxide. The longevity of haloalkanes in the atmosphere contributes to their potency as greenhouse gases. Although HFCs are not an ozone depleting substance, they are an even more powerful greenhouse gas.

In the early 1970s, research hypothesized that CFCs destroyed stratospheric ozone molecules. Scientists stated that CFC molecules break down in the atmosphere after 50 to 100 years. The chlorine atoms released during this process then degrade tens of thousands to millions of ozone molecules. In 1976, the National Academy of Sciences issued a report asserting the academy’s acceptance of the role of CFCs in ozone destruction.

In 1985, a study by the British Antarctic Survey bolstered the ozone depletion hypothesis. The study showed that a hole had developed in the ozone layer over Antarctica. Scientists attributed the depletion of the ozone layer over Antarctica to the widespread use of CFCs. The international community responded quickly with over 20 nations signing the Vienna Convention for the Protection of the Ozone Layer in 1985. Although the Vienna Convention did not set CFC-reduction goals, the convention serves as a framework for international agreements on reducing ozone-depleting substances.

With the framework provided by the Vienna Convention, the international community began working toward a binding international treaty with specific ODS-reduction goals. On September 16, 1987, the Montreal Protocol on Substances that Deplete the Ozone Layer was opened for signature. The Montreal Protocol went into effect on January 1, 1989 after ratification by 29 countries and the European Economic Community. Today, 191 countries are parties to the treaty.

The Montreal Protocol and its amendments provide a goal-oriented mechanism for reducing and phasing out the production of ozone-destroying substances. The Montreal Protocol established a two-tiered system with different phase-out dates for industrialized and developing countries. The Montreal Protocol set a final CFC phase-out date of 1996 for industrialized countries and 2010 for developing countries. Industrialized nations must gradually phase out HCFCs by 2030, while developing countries have until 2040. HFCs are not regulated by the Montreal Protocol because they do not degrade ozone. The Kyoto Protocol to the United Nations Framework Convention on Climate Change (UNFCCC), however, regulates HFCs as greenhouse gases.

In 1991, the Second Meeting of the Parties to the Montreal Protocol established the Multilateral Fund for the Implementation of the Montreal Protocol. The Multilateral Fund provides financial and technical assistance to developing nations to assist in phasing out ODS. Between 1991 and 2005, the Multilateral Fund collected over $2.2 billion. The Multilateral Fund has been instrumental in assisting developing nations in meeting their ODS-reduction goals under the Montreal Protocol, and it has contributed assistance to over 5,500 projects in 144 nations, resulting in an annual reduction of over 150,000 metric tons of ozone-depleting substances.

Impacts and Issues

The Montreal Protocol has been a successful international treaty in both compliance and achievement. Former United Nations Secretary General Kofi Annan called the Montreal Protocol “perhaps the most successful international agreement to date.” The governments of 191 countries signed the Montreal Protocol in its first 20 years. Andorra, Iraq, San Marino, Timor Leste, and the Vatican City are the only countries that have not ratified the Montreal Protocol.

By the end of 2006, the parties to the Montreal Protocol had phased out 95% of all ozone-depleting substances. Production of ODS fell from more than 1.8 million metric tons in 1987 to 83,000 metric tons in 2005. Due to the long half-life of CFCs, however, the recovery of the atmospheric ozone levels has been slow.


AEROSOL: Liquid droplets or minute particles suspended in air.

GREENHOUSE GAS: A gas whose accumulation in the atmosphere increases heat retention.

KYOTO PROTOCOL: Extension in 1997 of the 1992 United Nations Framework Convention on Climate Change (UNFCCC), an international treaty signed by almost all member countries with the goal of mitigating climate change.

OZONE: An almost colorless, gaseous form of oxygen, with an odor similar to weak chlorine, that is produced when an electric spark or ultraviolet light is passed through air or oxygen.

PROPELLANT: Gas or liquid ejected by a rocket or other vehicle to make the vehicle move in the opposite direction.

ULTRAVIOLET RADIATION: The energy range just beyond the violet end of the visible spectrum. Although ultraviolet radiation constitutes only about 5 percent of the total energy emitted from the sun, it is the major energy source for the stratosphere and mesosphere, playing a dominant role in both energy balance and chemical composition.

Atmospheric chlorine levels did not begin to drop until 1997. Although the thinning in the ozone layer over Antarctica has improved to some degree, the largest hole in the ozone ever recorded occurred in October 2006. The hole measured 11.4 million square mi (29.5 million square km), which is an area larger than North America. By late 2007, the hole in the ozone layer had returned to its ten-year average. Scientists predict that Antarctic ozone levels could recover completely by the year 2075.

See Also Chlorofluorocarbons; Ozone Hole; Ozone Layer



Anderson, Stephen O., and K. Madhava Sarma. Protecting the Ozone Layer: The United Nations History. London: Earthscan Publications, 2005.

Parson, Edward A. Protecting the Ozone Layer: Science and Strategy. Oxford: Oxford University Press, 2003.

Web sites

NASA/Goddard Space Flight Center. “NASA Keeps Eye on Ozone Layer Amid Montreal Protocol’s Success.” September 18, 2007.

(accessed January 30, 2008).

United Nations Department of Public Information. “Montreal Protocol on Ozone-Depleting Substances Effective, But Work Still Unfinished, Says Secretary-General in Message for International Day.” September 7, 2006. (accessed May 6, 2008).

United Nations Development Programme. “20 Years of Success: Montreal Protocol on Substances that Deplete the Ozone Layer.” 2007. (accessed May 6, 2008).

United Nations Environment Programme. “The Montreal Protocol on Substances that Deplete the Ozone Layer.” 2000. (accessed January 28, 2008).

United Nations Environment Programme. “The Ozone Secretariat.” 2007. (accessed January 28, 2008).

United Nations Environment Programme. “The Vienna Convention for the Protection of the Ozone Layer.” 2001. (accessed May 6, 2008).

Joseph P. Hyder

Montreal Protocol

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Montreal Protocol


The Montreal Protocol on Substances That Deplete the Ozone Layer is a treaty that was negotiated in 1987 and was signed by 191 nations. The treaty, which took effect at the beginning of 1989, has been revised seven times (most recently in 1999), and provides a timetable for the phasing-out of the use of several types of compounds called halogenated hydro-carbons that are known to destroy atmospheric ozone.

Protection of ozone in the atmosphere is very important, since the compound absorbs ultraviolet radiation entering the atmosphere from the sun. Ultraviolet light can damage skin cells and can break apart genetic material inside cells, which can lead to harmful cell changes (mutations) including cancer.

The Montreal Protocol and its regularly scheduled revisions, which have provided achievable targets for nations to meet in reducing the manufacture and use of ozone-depleting chemicals, has been cited as an example of how nations can successfully

agree to and implement meaningful climate protective measures.

Historical Background and Scientific Foundations

Beginning in the 1930s, chlorofluorocarbons (CFCs) beganto bewidelyused inanvariety of manufactured products including refrigerators and spray cans. Also known as Freon, the five main formulations of CFCs were a safe, non-poisonous, and non-flammable replacement for harmful compounds such as ammonia.

Over the intervening decades, CFCs that were given off by the various products dissipated into the atmosphere. In 1973, scientists at the University of California, Irvine, discovered that CFCs persist for 20–100 years in the region of the atmosphere known as the stratosphere, and that the CFCs are broken apart by incoming ultra-violet light.

The destruction of the CFCs releases chlorine. It was proposed and later proven that the freed chlorine destroys another compound in the atmosphere called ozone. Bromine-containing halogenated hydrocarbons also destroy ozone.

Ozone is made up of three oxygen atoms. When intact, an ozone molecule is able to absorb the ultra-violet portion of incoming sunlight, reducing the amount of the radiation that reaches Earth. However, as ozone is depleted from the stratosphere, more ultra-violet radiation reaches Earth's surface.

Ultraviolet light possesses sufficient energy to break one or both of the strands of the genetic material (usually deoxyribonucleic acid; DNA) that is present inside plant, animal, and human cells. When this happens, the result can be a change (mutation) in the cells that survive. Although some changes are not serious, others are. For example, mutations that affect the controls on cell division can lead to the runaway growth and division of cells that is the hallmark of cancer. Indeed, ozone depletion and the resulting increased exposure to ultraviolet light has been linked to increasing rates of several types of cancer.

The longevity of CFCs means that even a single molecule can be very destructive over its lifetime. Indeed, a CFC molecule is approximately 10,000 times more potent as a greenhouse gas than carbon dioxide.

Concern over ozone depletion and the link between this depletion and an increased threat to health was heightened in the early 1980s by the discovery of the virtual absence of ozone in the atmosphere over Antarctica. Dubbed the ozone hole, this dramatic evidence of ozone depletion spurred the global community into action. The result was the Montreal Protocol.

The protocol imposes strict time deadlines for the phasing out of nearly 100 compounds that contain ozone depleting chlorine and bromine. The list includes CFCs and hydrochlorofluorocarbons (HCFCs). Through the 1990s, HCFCs were popular as replacements for CFCs since they are not as ozone-destructive. However, they are also scheduled to be phased out according to the protocol by 2030 in developed countries and by 2040 in developing countries.

The effect will be a nearly 50% reduction in the emissions of ozone-depleting chemicals.

Impacts and Issues

The Montreal Protocol is an evolving agreement. The protocol timetable includes regularly scheduled revisions, which allow new scientific discoveries and advances to be incorporated into the agreement. The latest meeting of the 191 participating nations took place in Montreal on September 12–21, 2007.


CHLOROFLUOROCARBONS: Members of the larger group of compounds termed halocarbons. All halocarbons contain carbon and halons (chlorine, fluorine, or bromine). When released into the atmosphere, CFCs and other halocarbons deplete the ozone layer and have high global warming potential.

OZONE: An almost colorless, gaseous form of oxygen with an odor similar to weak chlorine. A relatively unstable compound of three atoms of oxygen, ozone constitutes, on average, less than one part per million (ppm) of the gases in the atmosphere. (Peak ozone concentration in the stratosphere can get as high as 10 ppm.) Yet ozone in the stratosphere absorbs nearly all of the biologically damaging solar ultraviolet radiation before it reaches Earth's surface, where it can cause skin cancer, cataracts, and immune deficiencies, and can harm crops and aquatic ecosystems.

STRATOSPHERE: The region of Earth's atmosphere ranging between about 9 and 30 mi (15 and 50 km) above Earth's surface.

ULTRAVIOLET RADIATION: The energy range just beyond the violet end of the visible spectrum. Although ultraviolet radiation constitutes only about 5% of the total energy emitted from the sun, it is the major energy source for the stratosphere and mesosphere, playing a dominant role in both energy balance and chemical composition.

The Montreal Protocol has been very successful in curbing the use of CFCs. Although the global production of CFCs exceeded 1.2 million tons in 1983, by 2004 global production had declined to 70,000 tons.

An aspect of the protocol that has been cited as a model for other environmental agreements is the built-in financial support for developing countries, courtesy of money contributed by participating nations and agencies including the United Nations Environmental Programme, U.N. Development Programme, U.N. Industrial Development Organization, and the World Bank. The monetary assist given by the developed world to developing countries makes it easier for poorer nations to meet the protocol's reduction targets.

Emissions from developed nations have largely stopped, since products containing CFCs can no longer be sold. Still, production of CFCs does continue, and CFC-containing products continue to be sold and used in the developing and under-developed world.

This, combined with the longevity of CFCs in the stratosphere, continues to produce ozone destruction. The damage will continue until late in the twenty-first century.

As effective as the Montreal Protocol has been, it is not a complete solution, since the agreement is concerned with HCFCs and not with another potent ozone destructive type known as hydrofluorocarbons (HFCs). The protocol mandates a complete phase-out of HCFCs by 2030, but no targets have yet been set for HFCs.

See Also Berlin Mandate; Bonn Conference (2001); Delhi Declaration; Intergovernmental Panel on Climate Change (IPCC); Kyoto Protocol; Ozone Depletion; United Nations Framework Convention on Climate Change (UNFCCC).



Anderson, Stephen, K., and Madhava Sarma. Protecting the Ozone Layer: The United Nations History. London: Earthscan Publications, 2005.

Kaniaru, Donald. The Montreal Protocol: Celebrating 20 Years of Environmental Progress. London: Cameron, May 2007.

Web Sites

“NOAA Observes 20th Anniversary of the Montreal Protocol.” National Oceanographic and Atmospheric Administration, September 16, 2007. <> (accessed November 23, 2007).

“Montreal Protocol Could Be Model for Addressing Climate Change.” U.S. Department of State,October 18, 2007. <> (accessed November 23, 2007).

Brian D Hoyle

Montréal Protocol

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Montréal Protocol

Following the discovery of the Antarctic ozone hole in late 1985, various governments recognized the need for stronger measures to reduce the production and consumption of a number of chlorofluorocarbons (CFCs). CFCs, which are human-made chemicals widely used in manufacturing, have been found to deplete the ozone layer that shields the surface of Earth from harmful forms of solar radiation. During the mid-1980s negotiations began on the Vienna Convention for the Protection of the Ozone Layera framework treaty focused on cooperation in research, information exchange, and scientific assessment of the atmospheric ozone (O3) problemgovernment representatives discussed drafting a protocol controlling the use of CFCs, human-made chemicals widely used in manufacturing that deplete the ozone layer. However, no consensus could be reached. The Executive Director of the United Nations Environmental Programme (UNEP) established a working group to begin drafting such a protocol. The final agreement, which was concluded on September 16, 1987, reflects the contentious nature of the negotiations. For example, by Article V, developing countries with low consumption rates (e.g., Brazil, India, and Vietnam) that feared the protocol would hinder their economic development are allowed a ten-year delay in required compliance with targets and timetables for reducing ozone emissions.

However, countries have generally been aggressive and effective in implementing the protocol. By the time it came into effect on January 1, 1989, countries were already contemplating the protocol's modification and strengthening. Amendments and adjustments were agreed to in London (1990), Copenhagen (1992), Vienna (1995), Montréal (1997), and Beijing (1999). These modifications shortened the timetables for phasing out consumption of listed chemicals, added and funded the Montréal Protocol Fund, established the Implementation Committee, developed noncompliance procedures, and expanded the Technology and Economic Assessment Panels. These panels have addressed new issues as they have arisen, such as recycling and international smuggling of CFCs.

see also CFCs (Chlorofluorocarbons); Ozone; Treaties and Conferences.


Benedick, Richard Elliott. (1998). Ozone Diplomacy: New Directions in Safeguarding the Planet. Cambridge, MA: Harvard University Press.

Weiss, Edith Brown. (2000). "The Five International Treaties: A Living History." In Engaging Countries: Strengthening Compliance with International Environmental Accords, edited by Edith Brown Weiss and Harold K. Jacobson. Cambridge, MA: The MIT Press.

internet resource

Ozone Secretariat of the United Nations Environment Programme. "The Montréal Protocol on Substances That Deplete the Ozone Layer." Available from

Michael G. Schechter

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