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Edited by the University of Hawaii at Manoa (Honolulu, HI), approved on October 8, 2021 (review received on December 3, 2020)
The Montreal Protocol on Substances that Deplete the Ozone Layer (Montreal Protocol) can be further strengthened to control ozone-depleting substances and HFCs used as raw materials, provide additional protection for the stratospheric ozone layer and the climate system, and reduce plastic pollution. The premise of the raw material exemption is that the raw material poses a negligible threat to the environment; experience has shown that this is incorrect. Through its adjustment procedures, the Montreal Protocol can narrow the scope of raw material exemptions to reduce unintentional and unauthorized emissions, while continuing to exempt the production of time-limited essential-use raw materials. This upstream approach can effectively complement other efforts to reduce plastic pollution. Existing mechanisms in the Montreal Protocol, such as assessment teams and national implementation strategies, can guide the selection of environmentally sound alternatives to raw material-derived plastics. This article provides a framework for policymakers, industry, and civil society to consider how stronger actions under the Montreal Protocol can complement other chemical and environmental treaties.
Montreal Protocol on Substances that Deplete the Ozone Layer (Montreal Protocol) (1) Protect the earth from the harmful effects of ultraviolet (UV) radiation, which can cause skin cancer and cataracts, suppress the human immune system, destroy crops and ecosystems, and degrade plastics And paint and other materials. It can also protect the climate system because most ozone-depleting substances (ODS) are potent greenhouse gases (GHG), and ultraviolet radiation reduces the terrestrial capacity of plants as carbon sinks (2).
The Montreal Protocol and the Vienna Convention for the Protection of the Ozone Layer as the basis are widely regarded as the most effective environmental treaties formulated so far. In its 34 years of operation, the Montreal Protocol has eliminated about 98% of ODS production and restored the stratospheric ozone layer by about 2,065 (3⇓ –5). At the same time, the elimination of ozone-depleting substances avoids greenhouse gas emissions, which might otherwise equal or exceed carbon dioxide (CO2) (6) emissions. The protocol provides additional climate mitigation by preventing ultraviolet radiation from destroying terrestrial carbon sinks (2).
Parties to the Montreal Protocol have the opportunity to use their existing powers to narrow the scope of exemptions for raw materials that were initially considered to pose a negligible threat to the environment (1, 7, 8). Reducing the raw material exemption will provide additional protection for the stratospheric ozone layer and the climate system by reducing unintentional and sometimes unauthorized emissions. This will make it easier to identify and ban raw materials, otherwise they may be diverted to unauthorized trade and eventually released into the atmosphere.
In addition, since ozone-depleting substances and hydrofluorocarbon (HFC) raw materials are used to make plastics, reducing their exemptions may reduce plastic pollution on the production side, especially if flexible mechanisms under the Montreal Protocol and national implementation strategies help guide choices Environmentally sound alternatives, just as they did when ODS was eliminated (see SI appendix, items III and V). The control of upstream raw materials under the Montreal Protocol will complement current downstream efforts to reduce plastic pollution through reduction, recycling and clean-up programs, and will provide further economic incentives for innovation in the search for plastic alternatives.
In this article, we first outline the reaction pathways to make ODS, HFC and related raw materials into various plastics. Then we explain how the Montreal Protocol reduces unintentional and unauthorized ODS and HFC feedstock emissions. We also explained how the protocol uses industrial innovation to reduce the production of certain raw material plastics and replace them with environmentally sound alternatives. The further evolution of the Montreal Protocol to reduce the scope of raw material exemptions will require continuous international cooperation, which is consistent with the history of the Montreal Protocol.
Raw materials are substances that themselves undergo chemical transformation in the process of synthesizing other chemicals. In contrast, processing agents are also used in industrial chemical processes, but unlike raw materials, processing agents themselves do not undergo chemical conversion in the process. The manufacture, use, and disposal of raw materials and processing agents can generate harmful emissions at every stage of the process. The degradation of plastics can cause additional harmful pollution.
The use of ODS, HFC and related chemicals as raw materials to produce plastics through polymerization involves complex and multi-step chemical pathways. The chemical approach was chosen for economic reasons, including obtaining raw materials and energy, solving process patents controlled by competitors, or co-producing other chemicals to minimize costs and maximize profits. The polymerization pathways reviewed here show that controlling ODS, HFC, and related raw materials under the Montreal Protocol can be part of an effective way to reduce plastics. Item IV of the SI Appendix provides a list of the names, chemical formulas and structures of the chemicals under discussion and their regulatory status under the Montreal Protocol.
Table 1 illustrates the reaction pathways from basic raw materials (column 1 in Table 1) to ODS and HFC raw materials controlled by the Montreal Protocol (column 2 in Table 1). Table 2 (together with the SI appendix, item I) illustrates the numerous chemical pathways (in Table 2) for the synthesis of chloro-fluorine-containing raw materials (mainly ODS and HFC, column 1 in Table 2) into the final polymer product (column 2) Column 3) in Table 2). The final product (plastics in many applications) is widely used in industry and daily life, and in some cases can cause environmental pollution that has nothing to do with stratospheric ozone depletion and climate warming. For example, the production of fluoropolymers generates emissions of perfluoro and polyfluoroalkyl substances (PFAS), some of which are used as polymer processing aids. People are seriously concerned about the toxicity and other harmful effects of PFAS on human health and the environment (9).
An indicative description of the basic raw materials and their reaction pathways to ODS and HFC (controlled by the Montreal Protocol), used as raw materials for the manufacture of plastics
Indicative reaction path between ODS and HFC raw materials and polymers based on a single type of monomer (applied as plastics)
Consider hydrochlorofluorocarbon-22 (HCFC-22), an ODS raw material made from chloroform, as shown in Table 1. As shown in Table 2, HCFC-22 in turn is used as a raw material for the production of tetrafluoroethylene (TFE), which is a component of the polymer polytetrafluoroethylene (PTFE), commonly known as Teflon, and is widely used in automobiles and textiles. , Construction and other industries. According to a recent survey (10), PTFE accounted for the largest proportion (~65%) of all fluoropolymer production in 2012, and its production is expected to double by 2022. Although there is no known chronic toxicity or carcinogenicity, PTFE will degrade and release harmful substances such as trifluoroacetic acid when heated to 250 and 600 °C (9, 11). In addition, polymer processing aids such as perfluorooctanoic acid (PFOA) and perfluorononanoic acid (PFNA) may be released during the manufacturing process. Both PFOA and PFNA are persistent, bioaccumulative and toxic substances that have a negative impact on human health (9). TFE also generates other synthetic materials through polymerization (see SI Appendix, item I); for example, nitroso rubber is formed through the reaction of TFE with perfluoronitrosoalkanes. Rubber, similar to plastic, can cause environmental pollution, especially after photodegradation (12).
Indicative raw materials controlled by the Montreal Protocol but exempt from phase-out
Another indicative example of environmental hazards is HCFC-142b, which can be produced from 1,1,1-trichloroethane (also known as T-111) related raw materials, as shown in Table 1. As shown in Table 2, HCFC-142b is used to produce vinylidene fluoride (VDF), which is the base material for polyvinylidene fluoride (PVDF) and various copolymers (such as poly(VDF-co-CTFE)) (See SI appendix, item I). PVDF is a non-reactive thermoplastic fluoropolymer, a specialty plastic used in chemical, electronic and energy-related applications. PVDF was the second largest (approximately 10%) of fluoropolymer production in 2012, second only to PTFE (10). Like PTFE, it poses a threat to human health (9) through harmful emissions during the manufacturing process and persistence in the environment.
In addition, many chloro-fluorine-containing unsaturated chemicals may be connected with various chemicals (such as ethylene, vinyl ether, vinylidene fluoride and bromofluoroolefin) and aromatic hydrocarbons (such as styrene and its derivatives) to form copolymers. Many of them eventually become plastics or other functional substances. Material. The collection of such copolymerization pathways and products is shown in item I of the SI appendix. For example, TFE made from HCFC-22 (see Table 2) can be polymerized with different monomers (such as propylene or ethylene) to form various types of heterogeneous copolymers (see SI appendix, item I). According to a recent survey (13), the four polymers listed in SI Appendix I — PTFE, FEP, ETFE, PFA and similar polymers — accounted for approximately 70% of the world's fluoropolymer consumption in 2015. % To 75%.
Table 2 and item I of the SI appendix show that about 70% to 80% (by type) of polymer products are used as plastics, especially thermoplastics, and most of the rest are used as elastomers. These tables also show that ODS, HFC and related raw materials have many ways to enter and remain in the environment as pollutants, especially as plastics, but can also be used as rubber and other materials. In fact, the extreme persistence of fluoropolymers, the potentially hazardous emissions associated with their production, use, and disposal, and the high likelihood of human exposure to PFAS, prove that restricting the production and use of plastics made from ODS and HFC raw materials is Reasonable, except for time-limited essential uses (9, 14).
It is estimated that the percentage of plastics derived from ODS and HFC raw materials in the total plastic production is highly uncertain (15), and further analysis is needed. Based on publicly disclosed data and chemical pathways, our preliminary estimate is that reducing the scope of exemptions for ODS and HFC raw materials may reduce as much as 6% of total plastic production. If other raw materials and chemical pathways are included in this "raw material-induced plastic reduction" method, this percentage will increase. For example, if the Montreal Protocol is amended to control vinyl chloride (and its related raw material ethylene dichloride), which is mainly made of polyvinyl chloride (PVC), the total output of plastics can be reduced by up to 20% (see SI appendix, item 2 ).
The regulation of additional raw materials through amendments to the Montreal Protocol may play an important role in reducing plastic, rubber and related air, land and aquatic environmental pollution. As a starting point, reduce the scope of exemption for ODS and HFC raw materials shown in Table 2 and Table 3 and SI Appendix I and related raw materials shown in Table 1 (for example, dichloromethane and chloroform, related raw materials) HCFC-22 and II Chlorinated ethylene (a related raw material for vinyl chloride) will make the production of such plastics technically or economically unfeasible. Following the practice before the adoption of previous adjustments and amendments, the detailed assessments of the Montreal Protocol Technology and Economic Assessment Panel (TEAP), Scientific Assessment Panel (SAP), and Environmental Impact Assessment Panel (EEAP) should guide the process of narrowing the scope of raw material exemptions and determining feasible alternatives.
The emission of ozone-depleting substances will deplete stratospheric ozone, thereby increasing ultraviolet radiation, leading to skin cancer and cataracts, weakening the human immune system, destroying agriculture and natural ecosystems, and degrading materials such as plastics and paints (3, 16). Most ODS also contribute to climate change (for example, see Global Warming Potential [GWP]100-y in Table 3). By 2010, unrestricted increase in ODS consumption may result in carbon dioxide equivalent equivalent to 2.4 to 76 billion metric tons of carbon dioxide equivalent each year (6). In addition, the increased ultraviolet radiation in the absence of the Montreal Protocol will reduce the capacity of terrestrial carbon sinks and is estimated to add 115 to 235 ppm of carbon dioxide to the atmosphere by the end of this century (2).
Increased UV radiation can also damage plants and animals at the bottom of the marine food chain (17, 18). In addition, climate warming is increasing the length and severity of heat waves, destroying food webs, and reducing fisheries (19). Finally, when ODS, HFC and related raw materials are converted into plastics, they will eventually pollute the land and the freshwater and marine environment. In particular, the earth’s oceans are threatened by man-made industrial, commercial, and consumer activities, including chemical pollution, overfishing, acidification, deep-sea mining, and plastic and other waste (20).
As of 2015, more than 6 billion metric tons (Mt) of plastic waste were generated globally; less than 10% of this was recycled, more than 75% ended up in landfills, and the remaining 15% was treated as increasing pollution. Geographically, plastic fragments have been found in all major ocean basins (21). The plastic flow into the ocean in 2016 is estimated to be 9 to 14 metric tons, and is expected to increase to approximately 29 metric tons by 2040 (22, 23). Most of the plastic discarded on the landscape in a relatively short period of time enters the ocean through water or wind, where they become entangled and ingested by marine life (24). Recycling does not always eliminate pollution because plastics can only be recycled once or twice (15).
If the microplastics in the ocean reduce the ability of phytoplankton to fix carbon through photosynthesis, the climate impact will be even greater (25). As plastics degrade, microplastics (0.1 to 5 microns in size) and nanoplastics (<100 nanometers in size) accumulate in aquatic and terrestrial organisms, with unknown long-term consequences for agricultural and marine productivity and food safety (26⇓ ⇓ ⇓ ⇓ ⇓ –32). Plastic fragments become permanent fragments that are easily entrained by wind. Dispersed plastics and microplastics and/or nanoplastics are ubiquitous in the ocean, from the digestive tracts of marine animals to the seabed. Microplastics were also found in the atmosphere and rainwater, with uncertain consequences (33⇓ –35). Due to their small size, microplastics and nanoplastics are extremely difficult to remove from the open ocean and atmosphere, which further supports the advantage of solving upstream problems by gradually reducing the raw materials used to make plastics (22).
In addition, plastics degraded by ultraviolet light and abrasion may contain high concentrations of toxic pollutants, such as polychlorinated biphenyls (PCB), nonylphenol (NP), dichlorodiphenyltrichloroethane (DDT), polycyclic aromatic hydrocarbons ( PAH), polybrominated diphenyl ethers (PBDE) and bisphenol A (BPA). Some of these toxic pollutants are highly resistant to environmental degradation caused by chemical, biological, and photolysis processes, and are controlled by the Stockholm Convention on Persistent Organic Pollutants (POP) (36, 37). In addition, some perfluorinated and polyfluoroalkyl substances pollutants, including perfluorooctanoic acid (9), which is used as a polymer processing aid in the plastic manufacturing process, are also controlled by the Stockholm Convention on Persistent Organic Pollutants.
As a “activation and strengthening” treaty, the Montreal Protocol has continuously improved its ambitions, including accelerating its ODS phase-out schedule, and passing five amendments (adding new controlled substances) and six adjustments to expand its scope to include New chemicals (accelerated phasing out of controlled substances) (38). This evolution includes expanding the scope of the treaty from its initial focus on protecting the stratospheric ozone layer, with climate mitigation as a side benefit, and expanding it to a clear focus on climate mitigation. The latter started with the accelerated phase-out of HCFCs in 2007, specifically for climate protection and ozone protection (39), followed by the Kigali Amendment in 2016 to phase out HFCs, and potent greenhouse gases have only a small amount of impact on stratospheric ozone.
The Montreal Protocol controls upstream hazardous chemicals at the source of production rather than downstream use. The success of this method is reflected in the successful elimination of approximately 98% of the world’s production and consumption of ODS (including raw material and process agent exemptions), including CFC, HCFC, CTC, halons, methyl bromide and methyl chloroform, which makes it advection The ozone layer was on the road to recovery in the middle of this century (3, 4, 17, 40). The Montreal Protocol also provides significant climate synergies: Without the Protocol, ODS emissions in 2010 would reach 15 to 18 gigatons (Gt) carbon dioxide equivalent (CO2-eq) per year (6). The Kigali amendment to phase out HFC will avoid CO2-eq⋅y-1 emissions of 2.8 to 4.1 Gt by 2050, and CO2-eq⋅y-1 emissions of 5.6 to 8.7 Gt by 2100 ( 5). By 2100, faster and gradual reductions in HFC may avoid temperature rises of up to 0.5 °C (5, 41, 42). In conjunction with the Kigali Amendment, the parties to the Montreal Protocol have also made a series of decisions to encourage the improvement of the energy efficiency of cooling equipment during the transition away from HFC refrigerants (42). The combined strategy can avoid the cumulative emissions of 130 to 260 Gt of carbon dioxide equivalent from 2030 to 2050 and the cumulative emissions of 210 to 460 Gt of carbon dioxide equivalent from 2030 to 2060 (42). In addition, by protecting the stratospheric ozone layer, the Montreal Protocol prevents damage to terrestrial carbon sinks. By the end of the 21st century, these carbon sinks will add an additional 115 to 235 ppm of carbon dioxide to the atmosphere and cause an additional 0.5 to 1.0°C. Warming global average surface temperature (2).
Many researchers described the reasons for the success of the Montreal Protocol and which environmental issues are most suitable for the Montreal Protocol method (16, 43⇓ ⇓ ⇓ ⇓ ⇓ ⇓ ⇓ –51). The success of the Montreal Protocol is partly due to the innovative operating philosophy and structure that make it ambitious and strictly enforced, while being flexible in key industry needs and responding to new scientific discoveries and technological advancements. This includes "start and strengthen", that is, starting with a politically acceptable phasing out schedule, and then stepping up to complete elimination by accelerating the initial schedule. The essential-use exemption allows the use of ozone-depleting substances that are considered critical to society for a limited time before the commercialization of alternatives, thereby allowing parties to make strict mistakes without the consequences of non-compliance. Over time, essential-use exemptions have gradually narrowed. Reducing the scope of the raw material exemption is consistent with the Montreal Protocol’s approach, and the requirements have been strengthened based on new scientific discoveries and technological advances.
The success of the Protocol is also attributed to the dedicated Multilateral Fund (MLF), which provides financial support to eligible developing countries to cover the agreed incremental costs of the transition to acceptable alternatives, as well as to the system of the National Ozone Unit Strengthen and train to promote compliance with the Montreal Protocol’s deadlines and monitoring and reporting requirements. The Montreal Protocol also uses its SAP, EEAP, TEAP and MLF to guide the development of technologies towards environmentally superior alternatives. The governments of various countries implement the mandatory control of the Montreal Protocol through regulations, as described in items III and V of the SI Appendix.
In addition, the Montreal Protocol has a history of successfully coordinating with other treaties and United Nations (UN) organizations on themes of overlapping concerns and authority. Examples include coordination with the International Plant Protection Convention during the phase-out of methyl bromide; negotiations with the International Civil Aviation Organization, the International Maritime Organization and the Montreal Unification of Certain Rules for International Air Transport when negotiating the elimination of halon used for aviation and maritime fire protection. Coordination with the UNFCCC on HFC and perfluorocarbons with the United Nations Framework Convention on Climate Change.
In terms of restricting raw materials and potentially helping to reduce plastic pollution, the Montreal Protocol will need to continue such coordination to understand the jurisdiction of other treaties and coordinate the efforts of other organizations, including the United Nations Environment Programme. In order to increase efforts to reduce plastic pollution, the United Nations Environment Assembly (UNEA) organized experts to review: 1) the current status of marine plastic litter and microplastics; 2) potential national, regional and international response options; 3) future and continued work at the global level The choice (52, 53). Importantly, the draft document of October 13, 2020 (54) includes concerns about upstream controls, as the Montreal Protocol proposes here. Ecuador, Germany, Ghana, and Vietnam organized a ministerial meeting in September 2021 to be the fifth UNEP meeting to be held in February 2022. Provide information for the resumed session. *In addition, a consortium of companies including 5 of the world's top 10 plastic polluters signed a declaration calling on the United Nations to formulate an international treaty on plastic pollution rules (55).
Parties to the Montreal Protocol have power over ODS and HFC, and can exercise this power to reduce the scope of the use of these chemicals as raw materials (1, 7, 8). In the early history of the Montreal Protocol, the parties’ actions assumed that raw materials were completely converted into other chemicals and would not be discharged or transferred to unauthorized trade (56, 57). When experience shows that the use of raw materials will emit a large amount of chemical substances, thereby destroying stratospheric ozone and warming the climate, the parties have taken a series of actions to reduce manufacturing emissions (58⇓ –60) (see SI appendix, item III and table A1 –A7), including requesting data reporting and evaluation team investigations (1, 59⇓ ⇓ –62).
Contracting parties also exercise the power to provide limited exemptions for raw materials. This includes first through adjustments and then through amendments, agreeing to amend the definition of "production", exempting controlled substances that are used exclusively as raw materials from the calculation of controlled substances for production and consumption (1, 3, 63). In addition, the two parties agreed to an adjustment that exempts "unintentional, unauthorized or coincidental production, unreacted raw materials or trace controlled substances used as processing agents in the manufacturing process, these substances are present in chemical substances as trace impurities, Or according to the definition of controlled substances, substances discharged during product manufacturing or processing" (58, 60). The parties later noted that this adjustment refers to raw material emissions, not raw material use or consumption (64).
Because the raw materials are incorrectly assumed to be non-emission or otherwise environmentally safe uses, the continuous production of raw materials exempted by the Montreal Protocol has led to an unauthorized market for chemicals that are subsequently illegally used as refrigerants and foam foam Agent (65, 66). For example, the SAP of the Protocol has long been concerned that the global atmospheric emissions of carbon tetrachloride (CTC) are far greater than what is explained by legal production. The chlorofluorocarbon CFC-11, which uses carbon tetrachloride as the relevant raw material, illustrates the problem of illegal raw material production and consumption. In 2018, scientists determined that the global atmospheric emissions of CFC-11 were far greater than what can be explained by the known production and product life cycle profiles (67). As shown in Table 1, CFC-11 is made of carbon tetrachloride and is usually co-produced with CFC-12. Warnings about possible unauthorized production of CTC, CFC-11 and CFC-12 have inspired scientists and environmental authorities to search for the source (68).
In 2019, scientists monitoring regional ODS concentrations showed that the increase in CFC-11 emissions, mainly occurring around northeastern provinces in China, accounted for at least 40% to 60% of the increase in global CFC-11 emissions (69). In 2020, scientists used innovative statistical methods to confirm the increase in emissions of CFC-11, CFC-12 and CFC-113 (70). In addition, as early as 2010, other scientists confirmed high levels of unwanted HFC-23 (with a very high GWP100-y; see Table 3), which is a by-product of HCFC-22 production, and the manufacturer has promised to minimize (71 ⇓ -73). Reducing the use of raw materials will reduce the production of illegal ozone-depleting substances and HFCs because there will be fewer facilities capable of producing these substances, and these substances can then be monitored more carefully.
Just as parties modified their treaties to exempt raw materials in 1990, they have the right to modify or cancel such exemptions. For raw chemicals that are already under the jurisdiction of the Montreal Protocol, parties should be able to use their adjustment procedures to narrow the scope of exemptions. The adjustment will automatically take effect for all parties after 6 months, except for those who definitely opt-out. Other raw chemicals can be added through modification. Contracting parties can still exempt the critical uses of raw materials, for example, in the production of substances necessary for the rapid replacement of high-GWP HFCs under the Kigali Amendment, and the use of HCFC-22 to produce polytetrafluoroethylene for medical applications, until There are suitable substitutes.
It is not yet possible to accurately quantify the amount of raw material emissions (absolute amounts and relative percentages) that can be avoided by reducing the scope of raw material exemptions under the Montreal Protocol, mainly because of inaccurate and incomplete reports on the production and use of raw materials. However, recent atmospheric monitoring has shown that the benefits of reducing the exemption for raw materials can be substantial. For example, between 2015 and 2017, 309 Tg CO2-eq of HFC-23 emissions were added to the atmosphere, roughly equivalent to Spain's total greenhouse gas emissions in 2017 (71). In addition, the global emissions of high global warming potential CFC-11, CFC-12, CFC-113 and HFC-23 (see Table 3) have exceeded the level explained by legal production and trace raw material emissions in the past few years ( 67, 70, 71). As Solomon et al. It was pointed out that “so far, the addition of CFC-11 is not enough to significantly delay the closure of the ozone hole, but the continued addition of CFC-11 after 2030 will hinder the successful healing of the ozone hole for ten years or more” (40) .
The Montreal Protocol provides an effective upstream method that has the potential to limit unintentional emissions and unauthorized production of ODS and HFC raw materials, while also reducing a large part of the production of plastics made from these raw materials. Comprehensive reduction of plastic pollution also requires a variety of strategies, including banning the use of disposable products, better collection and pre-sorting, reuse and recycling, and faster development of environmentally superior alternatives.
The protocol is a successful and flexible policy tool that is very sensitive to business and national economic issues. Fully implement the principles of common but differentiated responsibilities and respective capabilities. The Montreal Protocol’s success in protecting the ozone layer is well documented (2, 5, 74), as is its success in protecting the climate (3, 17, 68, 73, 75, 76). Agreeing to reduce the scope of raw material exemptions under the Montreal Protocol will be in line with the treaty’s "start and strengthen" evolutionary history, and will provide significant benefits, including reduced ozone depletion, reduced climate warming, reduced plastic pollution, and reduced harm to chemical workers And surrounding communities. Understanding the previously missing link between ODS and HFC raw materials and plastic manufacturing can inspire contracting parties to further strengthen the Montreal Protocol to better protect the environment and human health.
As a next step, parties to the Montreal Protocol can 1) provide more detailed and accurate raw material production reports, 2) require SAP to estimate the impact of reducing the scope of raw material exemptions on the atmosphere, and 3) require TEAP to identify and catalog alternatives currently using ODS and HFC Plastic made of raw materials. Under the guidance of MLF and TEAP, governments can continue to guide the selection of alternatives that are reasonably priced, technologically and environmentally superior.
All research data is included in the article and/or SI appendix.
We thank Deborah Rowan Wright (Policy Analyst at Marinet.org.uk) for encouraging the author to write this article to support the overall approach to restoring, protecting, and replenishing the world's oceans, and IGSD Research Assistant Trina Thorbjornsen, who was indispensable to the completion of this article. We would also like to thank IGSD science and policy analyst Kristin Leigh Campbell, IGSD senior scientist Dr. Gabrielle Dreyfus, Columbia University climate law researcher Korey Silverman-Roati, and IGSD intern Edanur Hardal for their contributions.
Author contributions: research on SOA, SG, and SC design; research on SG, TF, YW, and DZ; SOA, SG, SC, TF, MG, NJS, and DZ authored the paper.
The author declares no competing interests.
This article is directly contributed by PNAS.
This article contains online support information https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.2022668118/-/DCSupplemental.
↵*See the Ministerial Conference on Marine Garbage and Plastic Pollution held in Geneva, Switzerland from September 1st to 2nd, 2021. See also the online meeting of the Fifth Session of the United Nations Environment Assembly (UNEA-5.1), virtual from Nairobi, Kenya, February 22-23, 2021. The renewal meeting (UNEA-5.2) will be held in Nairobi, Kenya from February 28 to March 2, 2022.
This open access article is distributed under the Creative Commons Attribution-Non-Commercial-No Derivative License 4.0 (CC BY-NC-ND).
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