Montreal Protocol

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The Montreal Protocol on Substances that Deplete the Ozone Layer was signed on 16 September 1987 and entered into force on 1 January 1989. It was ratified by 193 countries.

Object and Issues

The problem of the depletion of the ozone layer in the stratosphere was revealed in the 1970s. Scientists blamed certain substances, such as CFCs (chlorofluorocarbons) and halons. These substances were being used in various industrial capacities, including gas propellants, cooling liquids, foams and solvents. During the 1980s, several events facilitated the emergence of an international plan for the protection of the ozone layer: the discovery of the hole in the ozone layer over Antarctica, a number of states adopting legislation prohibiting the use of certain substances in aerosols, and the development of alternatives for these substances. The Vienna Convention of 22 March 1985 sets out the general objectives for the protection of the ozone layer and puts in place a general framework for cooperation between parties in science, technology and law. The Montreal Protocol was negotiated subsequently, with the aim of setting a schedule and settling on precise objectives for the reduction and/or elimination of the production of substances that deplete the ozone layer (ODSs), leaving States free to choose the means of implementation.


The Protocol brought together parties to phase out their production and consumption of a group of ODS. To this end, a classification of these substances was drawn up in several annexes, put together with a specific timetable. Originally, only certain CFCs and halons were regulated, but Article 6 of the Protocol made provision for an evaluation of the efficacy of the measures taken to take place in 1990, according to scientific, environmental, technological and economic data (see below). Simple and efficient procedures in place allowed the rapid update of the annexes to the Protocol.

Whilst progressive, the system put in place by the Protocol had the potential to be difficult to adhere to. For this reason, the text made provision for the possibility of trading ODS production quotas between parties, to offer a degree of flexibility. In practical terms, this means that a State whose production levels are relatively low in the base year, can acquire the right to produce more than a state with surplus production levels. The Secretary to the Protocol must be notified of each transfer. The procedure is more closely supervised than exchanges relating to greenhouse gas emissions.

Effects and Application

Originally, the Protocol planned for a 50% reduction in CFC production and consumption, in about 10 years. But the adjustments and amendments subsequently adopted (in 1990, 1992, 1995, 1997, 1999 and 2007) have increased the number of substances and tightened the schedule, with the aim of eliminating completely the production of the majority of the regulated substances. It was agreed, from then on, to ban completely numerous CFCs, halons, carbon tetrachlorides, and methyl chloroform (1,1,1-trichloroethane), as well as several transition substances. These included HCFCs and HBFCs, substitution products for CFCs which had the potential to damage the ozone layer.

In addition, specific arrangements were made for developing countries. These countries were becoming significant ODS consumers, especially in developing their cold chains (temperature controlled supply chains). They are therefore entitled to a 10 year delay period, linked to the Protocol’s fixed schedule.

Finally, a number of commercial measures are intended to encourage the largest number of States possible to adhere to the Protocol. Thus the commercial exchange (import and export) of regulated substances with non-party states is forbidden (the duration of the prohibition varies according the ODS in question). The same restrictive trade rules apply to a list of products containing regulated substances, or products made using them, even if they do not contain them.

Regulating Implementation

It is here that the Protocol, in theory, is most innovative. It anticipates approval from the first Conference of Parties of the necessary procedures in case of non-compliance with the Protocol. This system is essentially based on cooperation. If one party is having difficulties fulfilling its obligations, or has reservations regarding their fulfilment towards another party, they can inform the Secretary, who can begin a mediation process. This procedure is then reviewed by the Implementation Committee, which is composed of representatives from parties to the Protocol. This political organ looks first for amicable solutions and if the need arises will pass on a report with recommendations to the Conference of Parties.

Several outcomes are possible: the adoption of the recommendation, a caution, proposals of technical, technological or financial assistance. But as a final resort, if these incentives are ineffective or in the case of bad will shown by the State concerned, sanctions can be imposed (commercial sanctions, withdrawal of financial assistance, etc.), which is rare in international law.

However, it must be noted that the verification procedures for the implementation of the text, and the procedures following non-compliance have weaknesses, stemming from the data provided by the member-States themselves. States based this data on information provided by the private sector, which consists of almost all the producers and users of harmful substances (with the exception of the military sector, a large consumer of substances harmful for the ozone layer). As for the Implementation Committee and Secretary, they are too small to effectively carry out their surveillance role. Finally, the problem of smuggling must be mentioned: in a large number of countries the existence of a black market for CFCs and other ozone layer depleting substances has been observed.

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