Jump to Content Jump to Main Navigation
Max Planck Encyclopedia of Public International Law [MPEPIL]

Ozone Layer, International Protection

Stephen O Andersen, Durwood Zaelke, Kristen N Taddonio, Richard ‘Tad’ Ferris, Nancy J Sherman

From: Oxford Public International Law (http://opil.ouplaw.com). (c) Oxford University Press, 2021. All Rights Reserved.date: 25 October 2021

Sustainable development — Climate change

Published under the auspices of the Max Planck Institute for Comparative Public Law and International Law under the direction of Professor Anne Peters (2021–) and Professor Rüdiger Wolfrum (2004–2020). 

A.  Editor’s Note

1  K Madhava Sarma, who was the first executive director of the Montreal Protocol Ozone Secretariat and one of the authors of the original version of this entry along with Stephen O Andersen, Durwood Zaelke, and Kristen N Taddonio, passed away in 2010 at the age of 72. Richard ‘Tad’ Ferris and Nancy J Sherman joined the other original authors in preparing the 2021 update of the entry.

B.  Introduction and Background

2  The 1987 Montreal Protocol on Substances that Deplete the Ozone Layer (‘MP’) and its underlying framework convention, the 1985 Vienna Convention on the Protection of the Ozone Layer (‘VCPOL’), have successfully protected the ozone layer in the stratosphere, located 10 to 15 kilometres above the Earth (see also Atmosphere, International Protection; Framework Agreements). The ozone layer protects the earth from excessive ultraviolet (‘UV’) radiation that endangers human health by increasing skin cancer and cataracts and suppressing the immune system, and that also damages agricultural production, natural ecosystems, and the built environment. In 1970, Paul Crutzen of the Netherlands postulated that emissions of nitrogen oxides from agriculture and industrial sources such as supersonic transport (‘SST’) could reach and catalytically deplete the thin layer of stratospheric ozone, and thereby also impact climate. In 1974, Mario Molina of Mexico and F Sherwood Roland of the United States warned that emissions of chlorofluorocarbons (‘CFCs’) and other manufactured halocarbons (‘Ozone Depleting Substances’ or ‘ODSs’) constitute a grave threat to the ozone layer. In 1975, Veerabhadran Ramanathan warned that halocarbons are also powerful greenhouse gases (‘GHGs’) that force climate change. In 1995, Crutzen, Molina, and Rowland shared the Nobel Prize for Chemistry for their groundbreaking science. In 2007, Guus JM Velders, Stephen O Andersen, John S Daniel, David W Fahey, and Mack McFarland showed that without the MP, climate forcing by ODSs in 2010 would have almost equalled the forcing from carbon dioxide (‘CO2’) in 2010, which would have had disastrous and irreversible consequences for the Earth’s environment and populations. In 2007, the MP accelerated the phasedown of hydrochlorofluorocarbons (‘HCFCs’) explicitly for climate protection in addition to ozone protection. In 2007, Donald Kaniaru, Rajendra Shende, Scott Stone, and Durwood Zaelke described the importance of the MP for reducing the risk of abrupt climate changes. In 2009, Molina, Zaelke, Sarma, and Andersen published a blueprint for fast climate mitigation, leading with strengthening climate protection under the MP by phasing down hydrofluorocarbons (‘HFCs’), which do not destroy ozone but are powerful climate forcing substances. Over time, the MP has been strengthened by amendment to control more ODSs and been accelerated by adjustment to phase out ODSs faster. In 2009, the Federated States of Micronesia and Mauritius proposed an amendment (UN Doc UNEP/OzL.Pro.WG.1/29/8 [18 July 2009]) to phase down the production and consumption of ozone-safe but high global warming potential HFCs, with the United States, Canada, and Mexico following with a similar amendment proposal in 2010. Other Parties joined various amendment proposals, and India submitted their own. In 2016, the MP Parties agreed to what became known as the HFC ‘Kigali Amendment’ to phase down production and consumption of HFCs, leaving emissions of HFCs to be controlled by the United Nations Framework Convention on Climate Change (‘UNFCCC’). HFCs were once necessary to rapidly phase out ODSs to avoid ozone tipping points but are no longer necessary in most applications because economically and environmentally superior alternatives and substitutes are available.

3  ODSs are long-lived substances and were considered ‘wonder chemicals’ when invented in 1928 because they are colourless, odourless, non-toxic, non-flammable, energy efficient and inexpensive. Their use rapidly expanded to many industries and processes, such as aerosol cosmetic products, refrigeration, air conditioning, insulating foams, electronics metal cleaning, medicine, and firefighting. It was five decades before it was realized that ODSs threatened life on Earth.

4  The United Nations Environment Programme (UNEP) launched a World Plan of Action on the Ozone Layer in 1977 to study and suggest solutions to the problem (Biswas [1979] Appendix 2). UNEP also initiated diplomatic discussions to focus international attention on the matter (Benedick [1991]; Andersen and Sarma [2002]; Hunter Salzman and Zaelke [2015], update in progress). In the following years, scientists continued to confirm the depletion of the ozone layer. However, diplomatic negotiations proceeded slowly, with some governments and companies that manufactured ODSs arguing that the connection between ODSs and ozone depletion was only a theory that had not been confirmed with empirical observation.

5  In 1985, 34 governments agreed to a framework convention, the VCPOL. The discovery, also in 1985, of the destruction of the ozone layer above Antarctica during the Antarctic spring from August to November every year (the ‘ozone hole’) created a world-wide sensation. Subsequently, in 1987, 25 nations and the European Union (‘EU’) negotiated the MP, which was agreed the same year to impose mandatory controls on ODSs (Belgium, Canada, Denmark, Egypt, Finland, France, Germany, Ghana, Italy, Japan, Kenya, Mexico, Netherlands, New Zealand, Norway, Panama, Portugal, Senegal, Sweden, Switzerland, Thailand, Togo, United Kingdom, United States, Venezuela, and the EU). The Montreal Protocol soon became the first United Nations (UN) treaty with universal membership (every UN State a Party).

6  The VCPOL and the MP built upon general international legal principles (General International Law [Principles, Rules and Standards]), foremost that a State is responsible for activities under its jurisdiction or control that cause damage to another State or to areas beyond national control (Hunter Salzman and Zaelke [2015] 466–72; State Responsibility). The MP also pioneered new international legal principles, including: 1) first treaty organized on the precautionary principle of taking action before irreversible damage is evident (Precautionary Approach/Principle), 2) common but differentiated responsibilities and respective capabilities (Hunter Salzman and Zaelke [2015] 463–66; Common but Differentiated Responsibilities), including earlier phaseout control schedules for developed countries typically followed by a grace period of several years before the mandatory controls were applied to developing country Parties, allowing developing countries more time for phaseout, 3) financing by developed country Parties of the agreed incremental costs for ODS phaseout for developing country Parties qualifying under Art. 5 MP (ie a developing country whose annual consumption of MP-controlled substances is less than 0.3 kilograms per capita (MP Handbook 2020), and 4) standing scientific, environmental effects, and technology assessment panels that are authorized to publish reports without editing by Parties (Andersen and Sarma [2002]; see section D.5 below; see also MOP Decision I/3: Establishment of Assessment Panels; all decisions of the Meetings of the Parties to the Montreal Protocol ‘MOP’ are available at <https://ozone.unep.org/treaties/montreal-protocol/decisions/by-article> or <https://ozone.unep.org/treaties/montreal-protocol/decisions/by-meeting> [22 February 2021]).

7  The ozone protection regime controls production and consumption of the chemicals within its jurisdiction and has successfully eliminated about 99% of the production and consumption of controlled ODSs, with the exception of unexpected and unreported CFC-11 production, carbon tetrachloride (‘CTC’), and possibly CFC-12 production in China and maybe elsewhere (see discussion below). However, ODSs remaining in ‘banks’ (ODS produced but not yet emitted) of insulation foam, refrigerators, freezers, and air conditioners (CFC-12), both discarded and still in use, slow the speed of stratospheric ozone recovery and contribute to climate warming. Lickley and others (2020) found that ODS emissions from banks likely are larger than previously estimated, will delay the recovery of stratospheric ozone by up to six years, and will add the equivalent of about 9 billion metric tonnes of CO2 to the atmosphere. Modeling by Lickley and others also found that measured emissions of ODS CFC-113, a production feedstock chemical that is still allowed and normally isn’t banked, spiked around 2013, similarly to Montzka and others 2018’s finding of excessive CFC-11 emissions starting in 2012. Following Montreal Protocol enforcement actions, excess emissions of CFC-11 and related chemicals have dramatically declined since 2018, suggesting cessation of illegal CFC-11 production in China, although banks of CFC-11 may have increased by around 100,000 metric tonnes by 2020 (Montzka and others [2021]; Park and others [2021]; Tollefson [2021]).

8  Globally, the MP’s success in phasing out ODSs has prevented an estimated 19.1 million non-melanoma cancer cases, 1.5 million melanoma cases, 129 million eye cataracts, and 333,500 cancer fatalities over the period 1987–2060. Total quantified benefits are estimated at US$459 billion, with estimated costs at US$224 billion (Smith Vodden Rucker and Cunningham [1997]). This does not include the significant MP mitigation of climate change (Velders and others [2007]); Climate, International Protection). The 2016 Kigali Amendment to phase down HFCs will contribute significant additional climate mitigation and avoid up to 0.5°C of warming through end of century (Xu Zaelke Velders and Ramanathan [2013]). Additional efforts to promote the energy efficiency of cooling equipment will provide still more climate protection (Dreyfus and others 2020; Synthesis of the 2018 Assessment Reports of the Scientific Assessment Panel, the Environmental Effects Assessment Panel, and the Technology and Economic Assessment Panel [Synthesis Report 2018]).

9  Historically, the MP has taken actions to ensure high compliance with its mandatory control measures (Ozone Secretariat Handbook for the Montreal Protocol on Substances that Deplete the Ozone Layer [14th edn 2020] [‘MP Handbook 2020’] 444–570). These actions recently demonstrated dramatic success with respect to unexpected and unreported emissions of CFC-11 and CTC, and possibly CFC-12 (see detailed discussion in para. 39 below; see also Montzka and others [2018]; Lunt and others[2018]; Dhomse and others[2019]; Montzka and others[2021]; Park and others[2021]; Tollefson [2021]).

C.  1985 Vienna Convention on the Protection of the Ozone Layer

10  The VCPOL provides a framework for protecting the ozone layer by initiating research, reporting, information exchange, and promotion of national policies to protect the ozone layer. It does not mandate specific reductions of ODS production or consumption. A conference of State Parties (‘COP’; Art. 6 VCPOL; Conference [Meeting] of States Parties) and a treaty secretariat (Art. 7 VCPOL) were created. Parties are required to make every effort to reach agreement on any proposed amendment by consensus, or, if efforts at consensus have been exhausted and no agreement reached, amendments shall as a last resort be adopted by a three-fourths majority vote of the Parties present and voting at the meeting (Art. 9 (3) VCPOL). Each Party has to ratify subsequent amendments and protocols (Art. 9 VCPOL). However, any adjustment to an annex or an additional annex enters into force for all Parties without ratification by any Party, except for a Party that, within six months from the date of the communication of the adoption of the adjustment by the depositary, notifies that it is unable to accept the adjustment or annex (Art. 10 (2) (b) VCPOL). The VCPOL allows its protocols to adopt their own procedure for amendment or adjustment as decided by the Parties to the protocol in question. The Parties are required to settle disputes through negotiation or mediation and to notify at ratification that they accept either arbitration or submission of the dispute to the International Court of Justice (ICJ), or both (Art. 11 (3) VCPOL; Environmental Dispute Settlement). If a Party does not choose, the dispute shall be submitted to a conciliation commission whose decision is recommendatory (Art. 11 (4) VCPOL). No reservations to the VCPOL are permitted (Art. 18 VCPOL; Treaties, Multilateral, Reservations to). The VCPOL has successfully fulfilled its role as a framework for addressing the threat to the ozone layer.

D.  1987 Montreal Protocol on Substances that Deplete the Ozone Layer

11  Twenty-four governments and the EU signed the MP on 16 September 1987, only nine months after negotiations began in December 1986 (Benedick [1991). The Protocol instituted a mandatory freeze of production and consumption levels of eight CFCs and halons and a mandatory 50% reduction of consumption of the eight CFCs by 1998 and specifying that the MP would enter into force upon ratification by eleven Parties representing at least two-thirds of global ODS production (Tolba and Rummel-Bulska [2008]). Regulating upstream production and consumption of the factory-made ODS is in contrast to the approach of the UN climate regime, which focuses on downstream emissions of GHGs. The MP provided for a periodic review of its control measures based on scientific and technical assessments (Art. 6 MP). No reservations to the MP are permitted (Art. 18 MP). The MP can be amended to add new controlled substances to the control schedules and adjusted to modify control schedules. The Protocol was quickly ratified and entered into force on 1 January 1989, 15 months after it was signed. The MP has since been amended five times to add new chemical substances to the control schedules and adjusted six times to accelerate ODS phaseout schedules; it has never been adjusted to decelerate control schedules. The last adjustment to accelerate phaseout schedules was in 2007 to hasten the phaseout of HCFCs for both ozone protection and climate protection, and the last amendment was in 2016 to phase down ozone-safe but high global warming potential (GWP) HFCs (Amendments in London 1990; Copenhagen 1992; Montreal 1997; Beijing 1999; and Kigali 2016. Adjustments in London 1990; Copenhagen 1992; Vienna 1995; Montreal 1997; Beijing 1999; and Montreal 2007). (All MP citations in this text are to the latest version of the Protocol.)

1.  Objective

12  The Montreal Protocol is a ‘start and strengthen’ treaty that started with the ambition to reduce just a handful of ODSs, was strengthened to phase out ODS almost 100 ODSs, then, with ODS phaseouts nearly complete, was broadened in order to better protect climate by phasing down ozone-safe HFCs and increase energy efficiency. The original objective of the MP was to reduce ODS production and consumption to protect the ozone layer throughout the world according to time schedules developed on the basis of periodic scientific and environmental assessment, taking into account technical and economic feasibility, with climate mitigation as an implicit collateral benefit. Over time, the objective was strengthened to phase out these chemicals. The objective has expanded since 2007 to explicitly include climate change mitigation, including with the 2007 acceleration of the HCFC phaseout of chemicals that both destroy the ozone layer and contribute to climate change, and the 2016 Kigali Amendment to phase down high GWP HFCs that do not significantly affect the ozone layer but contribute to climate change. In addition, the Parties have taken specific decisions to mitigate climate change by encouraging energy efficiency during the transition to environmentally superior alternatives: Decision XXVIII/3: Energy Efficiency in 2016 instructed the MP Technology and Economic Assessment Panel (‘TEAP’) to review energy efficiency opportunities in the refrigeration and air-conditioning sectors related to a transition to climate-friendly alternatives, and Decision XXVIII/2: Decision related to the Amendment Phasing down Hydrofluorocarbons in 2016 requested the Executive Committee to develop guidelines for financing the HFC phasedown, including cost guidance for maintaining and/or enhancing the energy efficiency of low- or zero-global GWP replacement technologies and equipment when phasing down HFCs (MP Handbook 2020; Seki [2018]).

2.  Chemicals Covered

13  The MP now covers 96 ODSs and 18 ozone-safe but high GWP HFCs, which are chemicals that contain hydrogen and fluorine atoms. The damage that these chemicals cause to the ozone layer over their entire atmospheric lifetime is weighted using a metric called ozone depletion potential (‘ODP’), while the damage ODSs and HFCs cause to climate over specified time periods (typically 100 years) is measured according to GWP, expressed in CO2 equivalents. Many ODSs are also powerful GHGs. The production or consumption of each group of ODSs is defined as the sum of ODP-weighted production or consumption of ODSs in that group (Art. 3 MP). The production or consumption of HFCs is controlled on the basis of GWP-weighted CO2 equivalents (Art. 3 MP). An inflexibility of the MP is that ODPs and GWPs are specified in a referenced scientific document but not updated as their impact on ozone depletion and climate forcing changes as a consequence of emissions of ODSs, HFCs, other GHGs, and black carbon. All ODSs except HCFCs have a phaseout schedule, subject to essential or critical use exemptions that must be approved by a Meeting of the MP Parties (‘MOP’). The HFCs have phasedown schedules, without access to essential use exemptions and trade provisions so far.

14  CFCs were used in refrigerators; air conditioners; cosmetic, convenience, and technical aerosol products; solvent cleaning; flexible and rigid foam; medical; and other applications. Halons were used primarily in fire protection. Methyl bromide was and still is used primarily for pest control. Carbon tetrachloride is used as a feedstock for refrigerants, in firefighting, and as a dry-cleaning solvent. Methyl chloroform was primarily used as solvent. Hydrobromofluorocarbons (‘HBFCs’) were not widely used when the MP was signed but were added to the list of controlled substances to prevent any new uses. HCFCs had uses before the MP primarily as refrigerants and, during the transition away from fully halogenated ODSs, as substitutes for CFCs. Additional HCFCs were developed as substitutes for CFCs as refrigerants, foam blowing agents, and solvents. While much less destructive than CFCs, HCFCs also contribute to ozone depletion and are potent GHGs. Methyl bromide (CH3Br) is used as a fumigant for high-value crops, pest control, and quarantine treatment of agricultural commodities awaiting export. Bromochloromethane (‘BCM’), an ozone-depleting substance that some companies sought to introduce into the market in 1998, was targeted for immediate phaseout to prevent its use. HFCs are primarily used as ODS substitutes for refrigerants in refrigerators, air conditioners, and heat pumps; as blowing agents in thermal insulating foam; as aerosol propellants and solvents; in metered dose inhalers (‘MDIs’); for fire protection; and in miscellaneous solvent, laboratory, and analytical uses.

15  HFC-23 is a powerful GHG (GWP100 12,690; lifetime 228 years) that is emitted to the atmosphere as an unwanted by-product of HCFC-22 production. The Kigali Amendment includes HFC-23 in the phasedown schedule with other HFCs (MP, Annex F) and requires that HFC-23 is destroyed ‘to the extent practicable’.

16  As of February 2021, the MLF Executive Committee has not been able to agree on measures to implement the HFC-23 controls specified in the Kigali Amendment (Decision 84/90 UN Doc UNEP/OzL.Pro/ExCom/84/75), largely because of technological and policy issues in certain HFC-23 producing countries (UN Doc UNEP/OzL.Pro/85/63). The Kigali Amendment requires that Parties destroy HFC-23 emissions produced in each twelve-month period starting 1 January 2020 to the extent practicable in the same twelve-month period using technology approved by the Parties (Kigali Amendment Art. 2J, paras 1–4, 6–7, Art. 3, para. 1 (d). See also Key Aspects Related to HFC-23 By-Product Control Technologies, UN Doc UNEP/OzL.Pro/ExCom/78/9). Parties also are required to determine and calculate their HFC-23 emissions and provide the Secretariat with statistical data of their emissions per facility, including amounts emitted from equipment leaks, process vents, and destruction devices, but excluding amounts captured for use, destruction, or storage (UN Doc UNEP/OzL.Pro.28/12 [15 October 2016]). This information informs the MLF Executive Committee with respect to the consumption, production, and servicing sectors and helps to quantify HFC-23 emissions, which are a by-product of the HCFC-22 production process. Recent measurements show HFC-23 emissions unexpectedly increasing (Stanley and others [2020]).

17  Although they agreed to it, some Parties were defensive about the total phaseout of halons and methyl bromide. There are no effective replacements for halons for some applications even now, and the aviation industry has procrastinated in implementing available alternatives and eliminating leaks and accidental discharge. However, a large quantity of halons in equipment that could use alternatives was recovered and recycled. As a result, production of halons was completely halted from 1 January 1994, with one small exception for Halon 2402, used by equipment made in the former Soviet Union and not recycled adequately. This is an astonishing result, given that phaseout of halons was considered impossible. Controlling methyl bromide also was a challenge. Alternatives to methyl bromide often had to be matched to particular agro-climatic conditions. Additionally, some developed countries supported their farmers, who feared that costlier alternatives to methyl bromide would make them less competitive with farmers in developing countries, who could continue to use the cheaper methyl bromide during the ten-year grace period allowed to them (Porter Banks Mattner and Fraser [2010]; Parson [2003]). Parties annually approve exemptions for ‘critical’ methyl bromide uses. However, with experience, claims of prohibitively higher agricultural production costs without methyl bromide have been discredited, and requests for such exemptions are less frequent.

3.  Adjustments and Amendments

18  The MP has an innovative procedure for adjustments of the ODP of ODSs and for further adjustments and reductions in production and consumption of ODSs (Art. 2 (9) MP). In the absence of consensus, the adjustments must be approved by two-thirds of the Parties present and voting, provided that a majority of both the Art. 5 (‘A5’) Parties, ie developing countries with baseline annual per capita consumption less than the quantity specified in Art. 5 MP (0.3 kg per capita) (MP Handbook 2020), and a majority of the non-A5 Parties present and voting approve the proposal. Despite the option of super-majority approval, Parties historically have always reached agreement by consensus (MP Arts 2, 9c; MP Handbook at 5). The adjustments are binding on all Parties, without the need for ratification, six months after being agreed, unless a Party affirmatively opts out. The second (London 1990), fourth (Copenhagen 1992), seventh (Vienna 1995), ninth (Montreal 1997), eleventh (Beijing 1999), and nineteenth (Montreal 2007) MOPs adopted adjustments to accelerate control schedules.

19  An amendment requires ratification, acceptance, or approval by each Party and is necessary to control additional substances, such as the HFCs, or if other articles of the MP are changed (Art. 2 (10) MP). Each of the amendments was a single package, even though each dealt with more than one group of controlled substances, or more than one aspect thereof. The second, fourth, ninth, eleventh, and twenty-eighth MOPs to the MP adopted five amendments to the MP. No Party can ratify the MP without ratifying the VCPOL. Also, before ratifying a later amendment, a Party has to ratify all the earlier amendments to the MP. Each Party determines its own schedule for ratifying, depending on its internal laws. On 16 September 2009, the VCPOL, along with the MP, achieved universal participation when all UN Member States ratified these agreements, and it became the first set of treaties of any kind in the history of the UN to achieve that status. As of 1 February 2021, the VCOPL and the MP have been ratified by all 198 UN Parties and the EU (European Union, Party to International Agreements), and the London, Copenhagen, Montreal, Beijing, and Kigali Amendments by 197, 197, 197, 197, and 113 (as of February 2021) Parties and the EU respectively (<https://ozone.unep.org/countries> [28 January 2021]). There has been no case of a Party refusing to ratify an amendment. The United States adopted legislation in December 2020 to implement an HFC phasedown consistent with the Kigali Amendment (Public Law No 116-260, Consolidated Appropriations Act, 2021, enacted 27 December 2020), and in January 2021, President Joe Biden issued an Executive Order directing the State Department to prepare the documentation to submit the Kigali Amendment to the US Senate for its advice and consent to ratification.

4.  Control of Trade

20  To discourage non-Parties from ‘free riding’ and to discourage Parties from shifting production to non-Parties, the MP prohibits trade in ODS between Parties and non-Parties, including trade in products containing or made with ODSs (Art. 4 MP). Additionally, Art. 4A MP prohibits trade with Parties that do not comply with the controls. Art. 4B MP mandates that all Parties implement a licensing system for import and export of ODSs. Trade with Parties that have not ratified the Kigali Amendment (ie ‘non-Parties’) will be banned from 1 January 2033 (Kigali Amendment C.N.872.2016.TREATIES-XXVII.2.f).

5.  Assessment Panels

21  The first MOP in 1989 established scientific, environmental effects, and technical and economic assessment panels. Later, the technical and economic assessment panels were merged into TEAP. The TEAP is assisted by experts serving on technical options committees (‘TOCs’). Members of the panels and co-chairs of the TOCs are nominated by the Parties. The Scientific Assessment Panel (‘SAP’) and Environmental Effects Assessment Panel (‘EEAP’) use chapters to divide the various topics for consideration. Governments can nominate experts but cannot insist on their inclusion. The membership in these bodies is generally equitable across regions but has not yet achieved the gender balance Parties have requested. Their reports are presented to the Parties as they are written, without editing by Parties.

6.  CBDR and Assistance for Developing Countries

22  The negotiators of the MP realized early that ozone depletion is a global problem impacting all. Emissions anywhere in the world would deplete the ozone layer. Developing countries consumed, in 1987, less than 15% of the ODSs worldwide and contributed little to the problem of the ozone depletion or climate impacts. However, their share of contribution to the problem increased with their increasing consumption of ODSs. The negotiators of the original MP included robust text intended to implement the principle of common but differentiated responsibilities (‘CBDR’), such as the original Art. 10 MP, which provided for technical assistance and the typical grace periods that allowed developing countries more time to meet mandated reductions. However, the original package of CBDR was not sufficient to attract full participation by developing countries. To ensure more favourable and equitable treatment of developing country Parties, Art. 10 London Amendment to the MP established a financial mechanism, the multilateral fund (‘MLF’), funded by non-A5 Parties to meet all agreed incremental costs of the A5 Parties’ implementation and compliance (Art. 10 MP). The 1990 MOP in London approved an indicative list of incremental costs (UNEP ‘Report of the Second Meeting of the Parties to the Montreal Protocol on Substances that Deplete the Ozone Layer’ [29 June 1990] UN Doc UNEP/OzL.Pro/2/3 Appendix 1). Art. 5 MP was amended to recognize that the implementation of the control measures by A5 Parties will depend on effective implementation of Arts 10 and 10A MP. As of December 2019, US$3.08 billion has been disbursed out of $3.32 billion approved by the MLF Executive Committee for phaseout of ODS. From 1991 through the end of 2019, 288,028 ODP tonnes of consumption and over 205,377 ODP tonnes of production were phased out, out of an anticipated total of 467,583 tonnes associated with approved projects. Of the 8,406 projects financed by the MLF, 7,636 have been completed since 1991, representing a 91% completion rate (UN Doc UNEP/OzL.Pro/ExCom/85/15).

23  Every Party is mandated to take every practicable step to transfer the best available substitutes and technologies to developing country Parties (Art. 10A MP; Technology Transfer).

7.  Key Features of the Financial Mechanism

24  Non-A5 Parties contribute to the MLF on the basis of the UN scale of assessments. The MLF is replenished every three years through a decision of the Parties at the MOP. The Parties decide the amount, after considering an expert assessment by the TEAP calculating the funds needed for enabling compliance. The MLF has been replenished seven times since it was established in 1990. The MLF is administered by an Executive Committee consisting of seven members from the A5 Parties and seven from non-A5 Parties, elected annually by the MOPs. The chairmanship and vice-chairmanship rotate between the two groups annually. The decisions of both the MOPs and the Executive Committee are made by consensus and, if a consensus cannot be achieved, through a majority vote in each group. Any bilateral contribution to the MLF by a country to meet the agreed incremental costs can be counted as a contribution up to 20% of the contributions due from that country, and such bilateral programmes require the approval of the Executive Committee.

8.  Global Environment Facility: Financing Countries with Economies in Transition

25  In the beginning of the 1990s, the then Union of Soviet Socialist Republics (‘USSR’) broke up into 20 independent republics. All the republics and also the countries of Eastern Europe gradually gave up communism to become market-oriented economies and experienced social and economic upheavals, from which some ultimately recovered. These ‘countries with economies in transition’ (‘CEITs’)—except Albania, Romania, and Yugoslavia—were classified as ‘developed countries’ (non-A5 Parties) and hence they were obliged to phase out most ODSs by 1996. They were in no position to do so. The Global Environment Facility (GEF) was established in 1991 to finance the incremental costs of eligible countries for global environmental problems, including ozone depletion, and provided financing to the CEITs to implement the control measures of the MP. As the MLF was established for financing A5 Parties, the GEF did not finance any A5 Parties. By 2012, the GEF had helped 18 CEITs to phase out ODS under the Montreal Protocol by investing $235 million in 29 projects, which leveraged another $247 million from GEF partners and resulted in the phaseout of 29,000 tons of ozone depleting potential (see <https://www.thegef.org/topics/ozone-layer-depletion> [20 January 2021]).

9.  Institutional Setting

26  The MP established the MOP (Art. 11 MP), the Secretariat (Art. 12 MP), and the Executive Committee to administer the MLF (Art. 10 (5) MP). Meetings of an open-ended working group (‘OEWG’) of the Parties, which typically are scheduled for five days, prepare for the annual MOP, which typically is also scheduled for five days. An Implementation Committee of ten elected Parties assists the MOP by considering and making recommendations on issues relating to non-compliance (Art. 8 MP; Environmental Treaty Bodies).

10.  Implementation Roles of Stakeholders

(a)  International and Bilateral Agencies

27  The World Meteorological Organization (WMO), in co-operation with UN Environment (‘UNEP’), US National Oceanographic and Atmospheric Administration, US National Aeronautics and Space Administration, and the European Commission, manages meetings and publishes the reports of the MP SAP and of the meetings of the ozone research managers of the Parties to the MP, which occur every three years. UNEP alerted the governments to the danger of ozone depletion in 1975 and continues to play a significant role in the implementation of the VCPOL and the MP. Under the stewardship of its Executive Director, Mostafa Tolba (1973–92), UNEP relaxed the traditional neutral role of UN organizations and guided negotiations towards the MP and its steady strengthening thereafter. Subsequent Executive Directors have been less proactive but the Ozone Secretariat as a whole has remained proactive. The role of UNEP as an implementing agency of the MLF is to create awareness and provide information on all issues of the MP. The United Nations Development Programme (UNDP), the United Nations Industrial Development Organization (UNIDO), and the World Bank (‘WB’) implement the MLF investment projects to convert industries and processes to ozone-safe technologies (see also World Bank Group), and non-investment projects are implemented by the UNEP Division of Technology, Industry and Economics (‘DTIE’) and its OzonAction Branch. The successful implementation of the MP by the A5 Parties is, in large measure, due to the effective functioning of these organizations as well as the national ozone officers and regional coordination offices.

28  The World Customs Organization (WCO) is the authority that harmonizes the commodity numbering system for monitoring trade in ODSs. The World Health Organization (WHO) is the source of information on the adverse effects of methyl bromide. The Food and Agriculture Organization of the United Nations (FAO) is the source of information about methyl bromide and its alternatives. Many bilateral aid agencies used part of their contribution to the MLF for bilateral assistance.

(b)  Industry

29  Industry has shifted from its original sceptical and often hostile position to being willing participants in international ozone layer protection. Industry has been critical to the success of ozone layer protection by serving on international technology assessment panels, by developing and promoting alternatives to ozone-depleting substances, and by serving as informal monitors for compliance with the MP. About half of the early members of the TEAP and its TOCs were from private industry (UNEP ‘Report of the Task Force on Continuing TEAP Legacy’ [April 2007], <https://ozone.unep.org/sites/default/files/2019-05/TEAP_2007_Legacy_Report.pdf> [22 February 2021]). Industry associations helped accelerate the development and introduction of alternatives to CFCs. Examples of industry cooperation include the Alternative Fluorocarbon Environmental Acceptability Study, Earth Technology Conference and Trade Show, Industry Cooperative for Ozone Layer Protection (‘ICOLP’), Halons Alternative Research Corporation, Japan Industrial Conference for Ozone Layer and Climate Protection, Alternative Fluorocarbon Environmental Acceptability Study, and the Programme for Alternative Fluorocarbon Toxicity Testing. The chemical industry helped compliance officials by reporting on illegal trade and provided the public with information on legal and technical risks associated with importing CFCs from suspicious sources (Benedick [1991]; Andersen and Sarma [2002]; Andersen Sarma and Taddonio [2007]). Ad hoc industry partnerships made various pledges, including phaseout pledges before they were mandated by the MP control schedule; phaseout within one year of the home-country schedule in facilities owned in developed countries; investment in next-generation ozone-friendly technology in Vietnam with no dumping of obsolete products; and more. A dozen companies donated patented technology to the public domain to speed ODS phaseout, and ICOLP disclosed and trained all interested enterprise in no-clean soldering, which revolutionized electronics manufacture.

(c)  NGOs

30  Non-governmental organizations (‘NGOs’) played a diverse and important role in ozone layer protection (see also Environment, Role of Non-Governmental Organizations). Environmental law organizations, such as the Natural Resources Defense Council and the Institute for Governance & Sustainable Development (‘IGSD’), participated in legislative, administrative, and judicial processes in the US to control the use and marketing of ODS products. Environmental policy and research organizations such as the Centre for Science and Environment, India and the World Resources Institute US, concentrated on policy analysis and communication. Greenpeace, Friends of the Earth, Consumer Unity and Trust Society, and other large environmental organizations launched campaigns demanding action. The Pesticide Action Network worked on implementing methyl bromide alternatives, the Environmental Investigation Agency focused on illegal production and trade, the Center for International Environmental Law organized technical cooperation workshops between the USSR, and private enterprises from Europe, Japan, and North America, and IGSD organized the scientific evidence and publications supporting the 2007 acceleration of the HCFC phaseout (Velders and others [2009]; Solomon and others [2010]; Velders and others [2012]; Zaelke Andersen and Borgford-Parnell [2012]; Molina and Zaelke [2013]; Montzka and others [2015]; Velders and others [2015]) and the 2016 Kigali Amendment controlling ozone-safe HFC GHGs.

(d)  Governments

31  National governments used many strategies to promote MP implementation. Customs codes and permits for production, import, and export of ODSs, product bans and use controls, sector phaseout schedules, refrigerant service procedures that included venting prohibition, recovery/recycling, service training and certification, and sale of ODSs only to certified technicians working in shops, ODS recycling, and manufacturing containment all played important roles. Economic incentives and disincentives in the market, such as government procurement preference for ODS-free products and ODS taxes, public disclosure of corporate and facility ODS emissions, fees, and trading and auctioning schemes were introduced. Public awareness and consumer empowerment, including educational campaigns, labelling requirements (official, third-party, or self-certification), industry education, review and approval of ODSs alternatives, equipment standards, establishment of halon banks, and research and development were other key government activities.

(e)  Collaboration among Stakeholder Groups

32  Collaboration among stakeholder groups and quasi-governmental activities, such as industry standard associations, health and medical registration, voluntary government/industry programmes, company pledges, and industry/government/NGO partnerships also played a role in the successful implementation of the MP. For example, automobile manufacturers developed standards through the Society of Automotive Engineers (now SAE International), which helped to complete the phaseout of CFC-12 (CCl2F2-dichlorodifluoromethane) around 1994 in developed countries and in the early 2000s in developing countries. HFC-134a (HFC-134a, or 1,1,1,2-tetrafluoroethane) was selected to replace CFC-12 because it had comparable cooling performance, low toxicity, non-flammability, no ozone depletion potential, and a global warming potential about eight times lower than CFC-12 (IPCC’s 5th Assessment Report lists HFC-134a’s 100-year GWP as 1300, versus 10,200 for CFC-12). After the transition to HFC-134a, collaborative efforts between industry, government, and NGOs resulted in continual improvements to mobile air conditioning (‘MAC’) energy efficiency, cooling performance, and reliability. However, global HFC-134a emissions continued to rise rapidly, so the EU (then European Community ‘EC’) passed new laws in 2006 restricting the use of high GWP HFCs. The Mobile Air Conditioning F-Gas Directive (Directive 2006/40/EC of the European Parliament and of the Council of 17 May 2006 relating to Emissions from Air-Conditioning Systems in Motor Vehicles and Amending Council Directive 70/156/EEC OJ L161/12; ‘MAC Directive’) required vehicles to use refrigerants with GWP below 150, which allowed for selection between several refrigerants with GWP<150, including CO2 (R744), HFC-152a, and hydrofluoroolefin-1234yf (‘HFO’-1234yf, or 2,3,3,3-tetrafluoropropene). To incentivize the switch to low-GWP MAC refrigerants, the United States Environmental Protection Agency (‘USEPA’), National Highway Transportation Safety Administration, and the California Air Resources Board also granted credits toward vehicle GHG standards for low GWP refrigerants. Every global automaker selected HFO-1234yf as the new MAC refrigerant and began transitioning away from HFC-134a, with just one automaker offering CO2 MAC systems as an option at extra cost on select luxury vehicles. These decisions, and collaboration among industry, governments, and NGOs, placed the sector in a position to be well prepared to meet the HFC phasedown requirements of the 2016 Kigali Amendment to the Montreal Protocol. In 2020, SAE International completed standards development for HFC-152a secondary loop MACS, which are capable of lower life cycle carbon footprint and higher reliability than existing direct expansion MAC systems (Taddonio and others 2019).

11.  Compliance Control Mechanism

(a)  Reporting of Data

33  Reliable and timely reports by the Parties on production and consumption of ODSs under Art. 7 MP are the basis for monitoring the implementation of control measures (Environmental Compliance Control). The Parties initially experienced difficulties in collecting and reporting their data. Reporting improved gradually with national licensing systems, regulations, and training, assisted by the MLF.

(b)  Non-Compliance Procedure

34  The formal non-compliance procedure, as approved by the MOP, applies without prejudice to the original settlement of disputes procedure laid down in Art. 11 VCPOL (UNEP ‘Report of the Tenth Meeting of Parties to the Montreal Protocol on Substances that Deplete the Ozone Layer’ [3 December 1998] UN Doc UNEP/OzL.Pro.10/9 Annex II). Any Party can represent regarding another Party’s non-compliance. The Secretariat also may bring out any non-compliance during its analysis of data submitted under Art. 7 MP. A Party concluding that it is unable to comply fully with its obligations may inform the Secretariat of its reasons. No Party has so far submitted any representation regarding non-compliance by another. Cases noted so far, with a single exception, are from Secretariat reports on annual data. An exception was in 1994, when the Russian Federation and some Eastern European and former USSR Parties submitted a statement to the MOP that they might not be able comply with phaseouts. As evidenced by that case, a response to non-compliance measures can be made despite the lack of a formal finding of non-compliance (Decision VII/18: Compliance with the Montreal Protocol by the Russian Federation; Werksman [1996]). The Implementation Committee considers each case and makes recommendations to the MOP. The Implementation Committee can undertake, upon the invitation of the Party concerned, information gathering in the territory of that Party for fulfilling the functions of the committee. It functions in coordination with the Executive Committee of the MLF, and Parties have used the MLF funding process to prompt a return to compliance by ensuring that non-complying Parties implement plans of action, enact ODS-related legislation domestically, and/or speed up the implementation of investment projects (MLF ExCom UN Doc UNEP/OzL.Pro/ExCom/50/9).

(c)  Responses to Non-Compliance

35  The fourth MOP, in 1992, finalized a non-exhaustive ‘Indicative list of measures that might be taken by a Meeting of the Parties in respect of non-compliance with the Protocol’ (UNEP ‘Report of the Fourth Meeting of the Parties to the Montreal Protocol on Substances that Deplete the Ozone Layer’ [25 November 1992] UN Doc UNEP/OzL.Pro.4/15 Annex V). These measures are: 1) appropriate assistance is provided including assistance for the collection and reporting of data, 2) technical assistance, 3) technology transfer, 4) financial assistance, 5) information transfer, and 6) training. If these measures fail, cautions are issued. Suspension is the final response.

(d)  Experience with the Non-Compliance Procedure

36  The MOP takes a sympathetic view of the problem of non-reporting, with decisions urging Parties to report expeditiously and giving advice on how to improve reporting. In cases of non-compliance with control measures, the MOP requests the concerned Parties to submit benchmarks and annual targets to return to compliance. In a few cases of nonobservance of benchmarks, Parties were cautioned that more stringent action would be taken unless the Party achieved the benchmarks it promised. A primary example of MOP suspension of rights and privileges involves a 1995 MOP decision involving the Russian Federation. In that decision, the MOP, inter alia, restricted, following non-compliance, the Russian Federation from re-exporting ODSs from the Commonwealth of Independent States (CIS), including Belarus and Ukraine, to any Party to the Montreal Protocol (UNEP ‘Report of the Seventh Meeting of the Parties to the Montreal Protocol on Substances that Deplete the Ozone Layer’ [27 December 1995] UN Doc UNEP/OzL.Pro.7/12 Decision VII/18).

(e)  Record of Compliance

37  The MP’s historical record of non-compliance involves both A5 and non-A5 Parties (see, eg, Decision XIX/21: Non-Compliance in 2005 with the Provisions of the Montreal Protocol Governing Production of the Controlled Substances in Annex A, Group I, [CFCs] and the Requirements of Article 2 of the Protocol with Regard to the Transfer of CFC Production Rights by Greece; Decision XVIII/28: Non-Compliance with the Montreal Protocol by Kenya). Historically, the reporting of data has been fundamental to MOP determination of Party compliance with MP obligations (MP Arts 5 and 7). From 2002–2018, there have been at least 53 differently named Parties (mostly non-A5 but also including A5 Parties) cited in group or individual non-compliance decisions for non-compliance with the MP data reporting obligations (see eg Decision XIV/16: Non-Compliance with Data Reporting Requirement for the Purpose of Establishing Baselines under Article 5 Paragraphs 3 and 8 ter (d); Decision XV/16: Non-Compliance with Data Reporting Requirements under Article 7, Paragraphs 1 and 2 of the Montreal Protocol; Decision XV/17: Non-Compliance with Data Reporting Requirements under Article 7 of the Montreal Protocol by Parties Temporarily Classified as Operating under Article 5 of the Protocol; Decision XV/18: Non-Compliance with Data Reporting Requirement for the Purpose of Establishing Baselines under Article 5, Paragraphs 3 and 8 ter (d); Decision XVI/17: Data and Information Provided by the Parties in accordance with Article 7 of the Montreal Protocol l; Decision XVI/18: Non-Compliance with Data-Reporting Requirements under Articles 5 and 7 of the Montreal Protocol by Parties Recently Ratifying the Montreal Protocol l; Decision XVII/20: Data and Information Provided by the Parties in Accordance with Article 7 of the Montreal Protocol; Decision XVII/21: Non-Compliance with Data-Reporting Requirements under Articles 5 and 7 of the Montreal Protocol by Parties Recently Ratifying the Montreal Protocol; and Decision XXX/13: Data and Information Provided by the Parties in Accordance with Article 7 of the Montreal Protocol).

38  Notably, MOP data-reporting non-compliance decisions have historically avoided reference to the noncompliant Parties in the decision titles. Further, these non-compliance decisions reflect that MOPs have historically responded to these instances of non-compliance by urging the Parties to work with the implementing agencies to report requested data, sometimes as a matter of urgency and sometimes with offers of assistance to Parties in complying with their reporting obligations. Additional examples of non-compliance actions from the modern history of the MP are described below.

39  In May 2018, Montzka and others warned that emissions of CFC-11 had increased since 2012 above expected levels. This increase was observed despite a ban on CFC production and consumption since 1996 in non-A5 Parties and a ban since 2010 in A5 Parties. It is significant that CFC-11 is co-produced with CFC-12, but no unexpected emissions of CFC-12 have thus far been identified. CFC-12 may have been produced but not yet emitted if sold into uses such as refrigeration and air conditioning equipment, which mostly contain the refrigerant for a decade or more. Furthermore, the unexpected and unreported production of CFC-11 may also be the reason CTC emissions have been higher than expected, particularly in eastern China, as identified in Lunt and others in September 2018, since CTC is a feedstock for CFCs. In May 2019, Rigby and others reported that Chinese CFC-11 emissions account for at least half of the unexpected global increase through 2017, with the other half not yet attributed to a specific location, and not ruling out a China source. In December 2019, Dhomse and others found that the CFC-11 impact on ozone is currently relatively small, but, if these emissions indicate production for foam use, much more CFC-11 may be leaked in the future. Further, Dhomse and others indicated that, among other things, substantial future CFC-11 emissions of 67 Gg yr-1 would delay Antarctic ozone recovery by well over a decade. Montzka and others and Park and others reported in February 2021 that global CFC-11 emissions have returned to 2008–2012 levels, and carbon tetrachloride and CFC-12 emissions, possibly associated with CFC-11 production, declined shortly before the drop in CFC-11 emissions. As a result of the Montreal Protocol’s successful compliance enforcement actions, any delay in the recovery of stratospheric ozone likely will be avoided (Montzka and others 2021; Park and others 2021; Tollefson 2021).

40  As of early 2021, China is pursuing actions consistent with MP MLF Executive Committee decisions to provide more information and greatly strengthen monitoring and regulatory systems for ODS, including CFC-11 and CTC in particular (China Letter to Secretariat UN Doc UNEP/OzL.Pro.WG/1/41/INF/7; Decision XXXI/3: Unexpected emissions of CFC-11 and institutional processes to be enhanced to strengthen the effective implementation and enforcement of the Montreal Protocol). In the meantime, Montzka and colleagues have developed a scientific methodology to calculate the combination of actions that could offset ozone and climate impacts of the unexpected CFC-11 emissions (Zaelke and Ramanathan [2018]; Dreyfus and others [2019] Poster).

41  In January 2020, Stanley et al warned that—contradicting an expected HFC-23 emission drop by 87% between 2014 and 2017—atmospheric observations revealed an HFC-23 emission increase and that HFC-23 emissions in 2018 were higher than at any point in history. Stanley and others noted that it is possible that reported reductions have not fully materialized or that there may be substantial unreported production of HCFC-22, resulting in the unaccounted-for emissions of HFC-23 as a by-product.

12.  Results of the Montreal Protocol

42  The MP has solved the first great threat to the global atmosphere by putting the ozone layer on the path to recovery by about 2060. There is now empirical confirmation that the ozone layer is recovering, based on the MP’s success phasing out ozone depleting chemicals (Chipperfield and others [2015]; Solomon and others [2016]; Synthesis Report 2018). In addition, the MP has done more climate mitigation than all other international agreements by successfully phasing out CFCs and other ozone depleting substances. Citizen boycotts of products containing ODS, national laws in the US, Canada, and the EU, plus the MP, have avoided as much warming as CO2 is causing today (Velders and others [2007]).

43  The initial effort of the MP to mitigate climate change was an unacknowledged collateral benefit of phasing out CFCs and related ODS. However, the 2007 adjustment to the MP to accelerate the phaseout of HCFCs was done explicitly for climate mitigation, as well as for ozone mitigation. The evolution of the MP into a climate treaty continued with the 2016 Kigali Amendment to phase down HFCs, which are potent GHGs, but not ODSs. This is the first time the MP has taken jurisdiction of non-ODSs. The initial phasedown schedule under the Kigali Amendment will avoid about 90% of the potential 0.5°C of projected warming by 2100 (Xu Zaelke Velders and Ramanathan [2013]). The Kigali Amendment also requires Parties to use their best efforts to reduce HFC-23 byproduct, which will increase the climate mitigation from phasing down HFCs. Further climate mitigation would be available by accelerating the Kigali Amendment’s initial phasedown schedule or by capturing and either recycling or destroying HFCs from products at end-of-life.

44  Past phaseouts under the MP have catalyzed improvements in the energy efficiency of cooling equipment during the switch to more environmentally friendly refrigerants (US Environmental Protection Agency [2002]; Todesco [2005]). Beginning in 2016, MP Parties have taken a series of decisions to explicitly encourage improvements in energy efficiency. The efforts to improve energy efficiency have the potential to double the climate benefits of the Kigali Amendment (Synthesis Report 2018; Dreyfus and others [2020]).

45  The overall reduction of production and consumption of ODSs has been significant, and often beyond the mandate of the MP. The only allowed consumption of ODSs by non-A5 Parties is for ‘essential uses’ approved by the MOP from time to time and as feedstocks and process agents. A5 Parties reduced their production of ODSs for laboratory and analytical uses (‘LAU’) from a high of 257 tonnes in 2010 to 150 tonnes in 2017. CTC accounts for more than 98% of ODS for LAU use (September 2018 UNEP MP Technology and Economic Assessment Panel [TEAP] Report: Volume 4 Response to Decision XXVI/5(2) on Laboratory and Analytical Uses, Revision-October 2019, at 9, <https://ozone.unep.org/meetings/thirtieth-meeting-parties/pre-session-documents> [22 February 2021]). Production of halons, used in aviation fire suppression, ceased at the end of 2009, and only recycled or banked halon supplies are now used (UNEP MP September 2018 TEAP Report, Volume 2, Decision XXIX/8 on the Future Availability of Halons and Their Alternatives, <https://ozone.unep.org/meetings/thirtieth-meeting-parties/pre-session-documents> [22 February 2021]). Over 99% of global consumption of methyl bromide for MP-controlled uses had been phased out by the end of 2019 (UNEP MP TEAP Report, September 2020, Volume 1: Evaluation of 2020 Critical Use Nominations for Methyl and Related Issues, <https://ozone.unep.org/meetings/thirty-first-meeting-parties/pre-session-documents> [22 February 2021]).

13.  Significance in Practice and Evaluation

46  The ozone treaty regime has implemented and practiced many innovative principles and mechanisms, including:

  • •  The Montreal Protocol implements the precautionary approach/principle, which states that ‘where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation’ (UN Conference on Environment and Development ‘Rio Declaration on Environment and Development’ [14 June 1992] UN Doc A/CONF.151/26/Rev.1 vol I, 3, Principle 15; Stockholm Declaration [1972] and Rio Declaration [1992]), has been practiced by the Montreal Protocol.

  • •  The CBDR principle is aggressively implemented.

  • •  Control measures are updated frequently based on independent expert assessments. The experts of the assessment panels have been drawn from all regions of the world.

  • •  All decisions are taken by consensus, respecting and accommodating any minority views, which has facilitated implementation. In the case of amendments, Parties have taken immediate steps for their implementation.

  • •  There are many international partnerships among industry, the military, and NGOs for development and dissemination of environmentally superior technologies.

  • •  Simplified procedures are included for ‘adjustments’, which strengthen controls of chemicals already controlled under the MP, and such adjustments are binding on all Parties without ratification unless they affirmatively opt-out within six months.

  • •  Non-compliance procedures emphasize assistance to Parties not in compliance and have been applied flexibly to maximize compliance. These procedures are backed up with the potential for suspension of non-compliant Party rights and privileges, trade measures to address ‘free riders’, and risks that production will shift to compliant Parties.

  • •  The significant unreported and unexpected production and emissions of CFC-11, CTC, and possibly CFC-12 are not yet fully resolved, although atmospheric concentrations are returning to expected values, according to the latest measurements.

  • •  Emissions of HFC-23 are continuing despite mitigation efforts, and this issue is not yet resolved.

47  The MP is widely considered to be the most effective environmental treaty. The Synthesis Report 2018 states:

The atmospheric concentrations of both total tropospheric chlorine and bromine from long lived ozone-depleting substances controlled under the Montreal Protocol have continued to decline since the 2014 assessments. Progress continues to be made in every consumer, commercial, industrial, agricultural, medical and military sector, with ozone-depleting substances having been phased out of many applications worldwide … presently, about 99 per cent of global reported controlled uses have been phased out (para. 5).

48  The MP also is the most successful treaty for mitigating climate change so far, having reduced GHG emissions by a net of 135 billion tonnes of CO2-equivalent, or 11 billion tonnes per year, from 1990 to 2010, and delaying climate forcing by seven to twelve years. This is significantly more than the reduction of 1 billion tonnes of CO2 equivalent per year mandated by the Kyoto Protocol during its first commitment period from 2008–2012. When early voluntary and national measures to reduce ODSs are included from 1974 onwards, the mitigation would have reached the equivalent of 24–76 billion tonnes of CO2 per year by 2010 and delayed climate forcing from 35 to 41 years, avoiding as much as or more warming than CO2 is causing today (Velders and others [2007]; Rogelj and others [2014]).

49  Compliance with the initial phasedown schedule under the Kigali Amendment is projected to reduce average global warming caused by HFCs from a baseline of 0.3°C–0.5°C by 2100 to less than 0.1°C. An accelerated phasedown schedule would reduce climate warming from HFCs still further. In anticipation of the HFC phasedown, industry already is developing and adopting low GWP HFC alternatives and new applications, particularly in the refrigeration, foam, and air conditioning sectors (Synthesis Report 2018 paras 18–19). The avoided warming from destroying HFC-23 is not included in these temperature calculations.

50  Each refrigerant transition required by the MP—from CFCs to HCFCs and from HCFCs to HFCs—has provided opportunities to install new equipment with higher energy efficiency. The 2016 Kigali Amendment builds on this pattern by promoting energy efficiency enhancements as part of the transition away from high-GWP HFCs. The Amendment requires the MP MLF Executive Committee to develop cost guidelines associated with maintaining and/or enhancing the energy efficiency of low-GWP or zero-GWP technologies and equipment that will replace existing technologies and equipment (MP MOP Decision XXVIII/2: Decision related to the Amendment Phasing down Hydrofluorocarbons). The Amendment also provides funding to maintain energy efficiency in the servicing/end user sectors during the transition away from HFCs (MP MOP Decision XXVIII/2 para. 16]). The MLF Executive Committee also is considering measures to implement MOP Decision XXX/5: Access of Parties Operating under Paragraph 1 of Article 5 of the Montreal Protocol to Energy-Efficient Technologies in the Refrigeration, Air-Conditioning and Heat-Pump Sectors, which, in addition to increasing funding for low-volume-consuming Parties (HFC baseline consumption up to 360 metric tonnes) to introduce low and zero GWP alternatives to HCFCs, would allow flexibility in use of MLF financial support provided for enabling activities that would increase energy efficiency during the HFC phasedown, such as pilot projects, updated training materials, certification of technicians, and outreach programs regarding minimum environmental performance standards, training programs, and energy efficient refrigeration, air conditioning, and heat pump equipment with low- or zero-GWP refrigerants (UN Doc UNEP/OzL.Pro.30/11).

51  Calculations by Lawrence Berkeley National Laboratory show that using today’s best available technology can cut cumulative emissions from the stationary air conditioning and refrigeration sectors by 38–60 GtCO2e by 2030, by 130–260 GtCO2e by 2050, and by 210–460 GtCO2e by 2060, depending on future rates of de-carbonization of electricity generation. A quarter of the mitigation is from phasing down HFC refrigerants and switching to alternatives with low GWP, while three-quarters is from ensuring that cooling equipment uses the best available technology to improve energy efficiency and reduce the use of electricity (Shah Wei Letschert and Phadke [2019]; Dreyfus and others [2020]).

52  Under the Kigali Amendment’s initial schedule, HFC emissions will be reduced by 33–47 GtCO2e by 2050. Installing high efficiency air conditioning and refrigeration equipment could at least double these climate benefits by reducing black carbon and CO2 emissions from electricity and diesel used to run this equipment. Public health and economic benefits would also accrue from reduced air pollution (Dreyfus and others [2020]; Purohit and others [2020]).

53  Some features of the MP have been incorporated in other global environmental agreements, including the 1992 UN Framework Convention on Climate Change and in its 1997 Kyoto Protocol. Areas for future work of the MP include disposal of ODS; recycling and destruction of banks of ODS- and HFC-containing foam, refrigerators, air conditioners, and other products; and control measures for nitrous oxide (‘N2O’), the last ODS not under the MP’s jurisdiction and also a climate forcer, used as a propellent, in surgery and dental work, in rockets and high-performance vehicle engines, and in agriculture. Scientific panels of the MP are also monitoring solar radiation management, which may become necessary to mitigate climate warming, including warming associated with CFCs, HCFCs, HFCs, and other chemicals regulated by the Montreal Protocol, and this could delay ozone recovery (UNEP Synthesis Report 2018, <https://ozone.unep.org/meetings/thirty-first-meeting-parties/pre-session-documents> [22 February 2021]). Measures to address climate change, including recycling and destruction of ODS banks, need to be considered using a full life cycle analysis approach (Lickley and others [2020]) such as life cycle climate performance, or LCCP (Papasavva and Andersen [2011]).

Select Bibliography

  • PJ Crutzen ‘The Influence of Nitrogen Oxides on the Atmospheric Ozone Content’ (1970) 96 Quarterly Journal of the Royal Meteorological Society 320–25.

  • M Molina and FS Rowland ‘Stratospheric Sink for Chlorofluoromethanes: Chlorine AtomCatalysed Destruction of Ozone’ (1974) 249 Nature 810–12.

  • V Ramanathan ‘Greenhouse Effect Due to Chlorofluorocarbons: Climatic Implications’ (1975) 190 Science 50–51.

  • A Biswas (ed) Ozone Layer (Pergamon Press Oxford 1979).

  • RE Benedick Ozone Diplomacy: New Directions in Safeguarding the Planet (Harvard University Press Cambridge 1991) 8, 68, 69.

  • J Werksman ‘Compliance and Transition: Russia’s Non-Compliance Tests the Ozone Regime’ (1996) 56 ZaöRV 750–73.

  • DA Smith K Vodden L Rucker and R Cunningham Global Benefits and Costs of the Montreal Protocol on Substances that Deplete the Ozone Layer (Environment Canada Ottawa 1997).

  • FS Rowland and MJ Molina ‘The CFC-Ozone Puzzle: Environmental Science in the Global Arena—John H Chafee Memorial Lecture on Science and Environment’ (National Council for Science and the Environment Washington 2001).

  • SO Andersen and KM Sarma (L Sinclair (ed)) Protecting the Ozone Layer: The United Nations History (Earthscan London 2002).

  • P Canan and N Reichman Ozone Connections: Expert Networks in Global Environmental Governance (Greenleaf Sheffield 2002).

  • US Environmental Protection Agency Building Owners Save Money, Save the Earth: Replace Your CFC Air Conditioning Chiller (US Environmental Protection Agency Washington DC 2002).

  • EA Parson Protecting the Ozone Layer: Science and Strategy (OUP New York 2003).

  • GM Bankobeza Ozone Protection: The International Legal Regime (Eleven International Publishing Utrecht 2005).

  • G Todesco ‘Chillers+Lighting+TES: Why CFC Chiller Replacement Can Be Energy-Savings Windfall’ (2005) 47(3) ASHRAE Journal 18–25.

  • D Zaelke D Kaniaru and E Kruíková (eds) Making Law Work: Environmental Compliance & Sustainable Development (Cameron May London 2005).

  • KM Sarma ‘Compliance with the Multilateral Environmental Agreements to Protect the Ozone Layer’ U Beyerlin P-T Stoll and R Wolfrum (eds) Ensuring Compliance with Multilateral Environmental Agreements: A Dialogue between Practitioners and Academia (Nijhoff Leiden 2006) 25–38.

  • SO Andersen KM Sarma and K Taddonio Technology Transfer for the Ozone Layer: Lessons for Climate Change (Earthscan London 2007).

  • D Kaniaru (ed) The Montreal Protocol: Celebrating 20 Years of Environmental Progress: Ozone Layer and Climate Protection (Cameron May London 2007).

  • D Kaniaru R Shende S Stone and D Zaelke ‘Strengthening the Montreal Protocol: Insurance Against Abrupt Climate Change’ (2007) 7 Sustainable Development Law & Policy 74–76.

  • GJM Velders and others ‘The Importance of the Montreal Protocol in Protecting Climate’ (2007) 104 Proceedings of the National Academy of Sciences 4, 814–19.

  • KM Sarma and D Zaelke ‘Start, Then Strengthen: The Importance of Immediate Action for Climate Mitigation’ (2008) 50 IISD’s MEA Bulletin, available at <https://enb.iisd.org> (22 February 2021).

  • MK Tolba and I Rummel-Bulska Global Environmental Diplomacy: Negotiating Environmental Agreements for the World, 1973–1992 (MIT Cambridge 2008).

  • M Molina and others ‘Reducing Abrupt Climate Change Risk Using the Montreal Protocol and Other Regulatory Actions to Complement Cuts in CO2 Emissions’ (2009) 106 Proceedings of the National Academy of Sciences (PNAS) 20,616–21.

  • GJM Velders and others ‘The Large Contribution of Projected HFC Emissions to Future Climate Forcing’ (2009) 106 Proceedings of the National Academy of Sciences (PNAS) 10,949–54.

  • I Porter J Banks S Mattner and P Fraser ‘Global Phaseout of Methyl Bromide Under the Montreal Protocol: Implications for Bioprotection, Biosecurity and the Ozone Layer’ in U Gisi I Chet and ML Gullino (eds) Recent Developments in Management of Plant Diseases. Plant Pathology in the 21st Century (Contributions to the 9th International Congress) vol 1 (Springer Dordrecht/Basel 2010) 293–309.

  • S Solomon and others ‘Persistence of Climate Changes Due to a Range of Greenhouse Gases’ (2010) 107 Proceedings of the National Academy of Sciences (PNAS) 18,354–59.

  • S Papasavva and SO Andersen ‘GREEN-MAC-LCCP©: Life-Cycle Climate Performance Metric for Mobile Air Conditioning’ (2011) 30 Environmental Progress & Sustainable Energy 234–47.

  • M Molina and D Zaelke ‘A Climate Success Story to Build On’ in Protecting Our Atmosphere for Generations to Come: 25 Years of the Montreal Protocol (UNEP OzonAction Nairobi 2012) 6.

  • GJM Velders and others ‘Preserving Montreal Protocol Climate Benefits by Limiting HFCs’ (2012) 335 Science 922–23.

  • D Zaelke SO Andersen and N Borgford-Parnell ‘Strengthening Ambition for Climate Mitigation: The Role of the Montreal Protocol in Reducing Short-Lived Climate Pollutants’ (2012) 21(3) Review of European Compliance & International Environmental Law 231–42.

  • M Molina and D Zaelke ‘A Comprehensive Approach for Reducing Anthropogenic Climate Impacts Including Risk of Abrupt Climate Changes’ in PJ Crutzen L Bengtsson and V Ramanathan (eds) Fate of Mountain Glaciers in the Anthropocene: Proceedings of the Working Group, 24 April 2011 Scripta Varia 118 (Pontifical Academy of Sciences Vatican City 2013) 1–12.

  • Y Xu D Zaelke GJM Velders and V Ramanathan ‘The Role of HFCs in Mitigating 21st Century Climate Change’ (2013) 13(12) Atmospheric Chemistry and Physics 6083–89.

  • J Rogelj and others ‘Disentangling the Effects of CO2 and Short-Lived Climate Forcer Mitigation’ (2014) 111 Proceedings of the National Academy of Sciences (PNAS) 16,325–30.

  • MP Chipperfield and others ‘Quantifying the Ozone and Ultraviolet Benefits Already Achieved by the Montreal Protocol Treaty’ (2015) 6 Nature Communications 7233–40.

  • D Hunter J Salzman and D Zaelke International Environmental Law and Policy (5th edn Foundation Press St Paul MN 2015).

  • SA Montzka and others ‘Recent Trends in Global Emissions of Hydrochlorofluorocarbons and Hydrofluorocarbons: Reflecting on the 2007 Adjustments to the Montreal Protocol’ (2015) 119 Journal of Physical Chemistry 4439–49.

  • GJM Velders ‘Future Atmospheric Abundances and Climate Forcings from Scenarios of Global and Regional Hydrofluorocarbon (HFC) Emissions’ (2015) 123(A) Atmospheric Environment 200–9.

  • D Zaelke and N Borgford-Parnell ‘The Importance of Phasing down Hydrofluorocarbons and Other Short-Lived Climate Pollutants’ (2015) 5 Journal of Environmental Studies and Sciences 169–75.

  • D Zaelke and others ‘Primer on HFCs: Fast Action under the Montreal Protocol Can Limit Growth of Hydrofluorocarbons (HFCs), Prevent 100 to 200 Billion Tonnes of CO2-eq by 2050, and Avoid up to 0.5°C of Warming by 2100’ (19 May 2017) IGSD Working Paper (IGSD Washington DC 2015), <http://www.igsd.org/wp-content/uploads/2017/11/HFC-Primer-19May20171.pdf> (22 February 2021).

  • S Solomon and others ‘Emergence of Healing in the Antarctic Ozone Layer’ (2016) 353 Science 269–74.

  • S Andersen K Taddonio M Soffer N Sherman et al ‘Economic and Climate Advantages: Secondary Loop Motor Vehicle Air Conditioners (MACs)’ (2018) SAE Technical Paper 2018-37-0030.

  • N Borgford-Parnell SO Andersen and D Zaelke Chapter 34 Fluorinated Greenhouse Gases in MB Gerrard and JC Dernbach (eds) Legal Pathways to Deep Decarbonization in the United States (Environmental Law Institute Washington DC 2018) 902–15.

  • MF Lunt and others ‘Continued Emissions of the Ozone-Depleting Substance Carbon Tetrachloride from Eastern Asia’ (2018) 45 Geophysical Research Letters 11,423–30.

  • SA Montzka and others ‘An Unexpected and Persistent Increase in Global Emissions of Ozone-Depleting CFC-11’ (2018) 557 Nature 413–17.

  • M Seki ‘Energy Efficiency in the Context of the Montreal Protocol and its Kigali Amendment’ (5 June 2018) Presentation, UNEP Ozone Secretariat, <https://www.asiacleanenergyforum.org/wp-content/uploads/2018/06/Meg-Seki-Energy-Efficiency-in-the-context-of-the-Montreal-Protocol-and-its-Kigali-Amendment.pdf> (3 May 2021).

  • WMO (World Meteorological Organization) ‘Scientific Assessment of Ozone Depletion: 2018’ Global Ozone Research and Monitoring Project: Report No 58 (Geneva Switzerland 2018).

  • D Zaelke and V Ramanathan ‘Unexpected, Unreported, and so far Unexplained Emissions of CFC-11’ (13 September 2018) Bulletin of the Atomic Scientists, <https://thebulletin.org> (22 February 2021).

  • SS Dhomse and others ‘Delay in Recovery of the Antarctic Ozone Hole from Unexpected CFC-11 Emissions’ (2019) 10 Nature Communications 1–12.

  • G Dreyfus SA Montzka SO Andersen and R Ferris ‘A Method for Calculating Offsets to Ozone Depletion and Climate Impacts of Illegal ODS Production’ (11 December 2019) [Poster] (American Geophysical Union), available at <https://ozone.unep.org/system/files/documents/IGSD-SideEvent-FinalPres-8Nov2019.pptx> (accessed 28 May 2021).

  • M Rigby et al ‘Increase in CFC-11 Emissions from Eastern China Based on Atmospheric Observations’ (2019) 569 Nature 546–50.

  • N Shah M Wei V Letschert and A Phadke ‘Benefits of Energy Efficient and Low-Global Warming Potential Refrigerant Cooling Equipment’ (Lawrence Berkeley National Laboratory Berkeley 2019), also available at <https://eta-publications.lbl.gov/sites/default/files/lbnl-2001229_final_0.pdf> (22 February 2021).

  • K Taddonio N Sherman and SO Andersen ‘Next Generation Refrigerant Transition: Lessons Learned from Automotive Industry Experiences with CFC-12, HFC-134a and HFO-1234yf’ (2019) SAE Technical Paper 2019-01-0909.

  • G Dreyfus and others ‘Assessment of Climate and Development Benefits of Efficient and Climate-Friendly Cooling’ (Institute for Governance & Sustainable Development and Centro Mario Molina Washington DC 2020), available at <https://ccacoalition.org> (22 February 2021).

  • M Lickley and others ‘Quantifying Contributions of Chlorofluorocarbon Banks to Emissions and Impacts on the Ozone Layer and Climate’ (2020) 11 Nature Communications 1380.

  • KM Stanley and others ‘Increase in Global Emissions of HFC-23 Despite Near-Total Expected Reductions’ (2020) 11 Nature Communications 1–6.

  • SA Montzka GS Dutton RW Portmann and others ‘A Decline in Global Emissions During 2018–2019 (2021) 590 Nature 428–32.

  • S Park and others ‘A Decline in Emissions of CFC-11 and Related Chemicals from Eastern China’ (2021) 590 Nature 433–37.

  • J Tollefson ‘Illegal CFC Emissions Have Stopped Since Scientists Raised Alarm’ (2021) 590 Nature 373.

Select Documents