Concentrations of ozone-depleting substances in the atmosphere are determined by the stock of substances, in addition to the balance of inputs and outputs over time. The lifetime of gases in the atmosphere plays an important role in understanding how their concentrations change over time. September 16 is World Oceans Day, marking the anniversary of the signing of the Montreal Protocol on Substances that Deplete the Ozone Layer, the historic international agreement focused on healing the ozone layer and protecting our planet from harmful ultraviolet (UV) rays. To learn more about World Ozone Day, check out this reportExitand the history of the Montreal Protocol and its implementation in the United States. The Montreal Protocol on Substances that Deplete the Ozone Layer, also known simply as the Montreal Protocol, is an international treaty aimed at protecting the ozone layer by phasing out the production of many ozone-depleting substances. It was signed on 26 August 1987 on the basis of the 1985 Vienna Convention for the Protection of the Ozone Layer, which provided the framework for international cooperation in combating the depletion of the ozone layer. [1] The Montreal Protocol entered into force on August 26, 1989 and has since undergone nine revisions, namely in 1990 (London), 1991 (Nairobi), 1992 (Copenhagen), 1993 (Bangkok), 1995 (Vienna), 1997 (Montreal), 1998 (Australia), 1999 (Beijing) and 2016 (Kigali). [2] [3] [4] In red/orange, we show the real trends in ozone-depleting substances, with the very obvious effects of the implementation of the Montreal Protocol on the reduction of greenhouse gas emissions and the plateau of radiative forcing. The blue trends reflect the estimated impact if the Montreal Protocol had not been adopted: it is based on the assumption of a 2-3 per cent increase in annual halogen production (dotted and solid line).
The blue zone therefore represents the estimated amount of greenhouse gases or radiative forcings that have been avoided through the Montreal Protocol. However, a 2018 study published in Nature reported “an unexpected and sustained increase in global ozone-depleting CFC-11 emissions.”7 In the graph, we see the amount of ODS consumption by country. This is measured in tonnes of ozone-depleting substances, all weighted in relation to their depletion potential. The graph shows the level of natural emissions (which was roughly constant over this period) and total emissions, which represent the sum of natural and anthropogenic emissions. Here we see a clear trend towards the reduction of the ozone layer, with a rapid increase in emissions (more than three times) from 1960 to the late 1980s, followed by an equally rapid reduction in the following decades. By 2010, emissions had returned to 1960 levels. This is largely the result of international regulatory agreements and concerted actions to phase out the production and consumption of these substances (which will be discussed later in this entry). Material: ELI members will then have access to documents/a recording of this session (usually published within 48 hours). If you are not an ELI member but would like to have access to archived sessions like this, go HERE to see the many benefits of membership and how to register. The fund is replenished by donors for three years.
Commitments amounted to $3.1 billion between 1991 and 2005. The funds will be used, for example, to finance the conversion of existing manufacturing processes, to train staff, to pay royalties and patent fees on new technologies and to establish national ozone offices. As of December 2019, the fund accounted for just over $4.1 billion in revenue and $3.8 billion in payments. [41] Montzka et al. (2018) reported that, since 2012, there has been an unexpected increase in emissions of trichlorofluoromethane (CFC-11), a historically dominant source of ozone-depleting substances, since 2012. But the Rowland-Molina hypothesis has been strongly contested by representatives of the aerosol and halocarbon industry. DuPont`s CEO was quoted as saying that the theory of ozone depletion “is a science fiction story. a pile of garbage. complete absurdity.” Robert Abplanalp, president of Precision Valve Corporation (and inventor of the first practical aerosol can valve), wrote to UC Irvine Chancellor complaining about Rowland`s public statements (Roan, p.
56). See the table in the next section for a list of substances and their respective ODP values. OdP values provide a measure of the relative destructive potential of one tonne of this substance relative to chlorofluorocarbon-11 (CFC-11). The CFC-11 therefore receives a value of 1. For example, HCFCs have an ODP between 0.01 and 0.1, which means that one tonne of HCFC gas causes 10 to 100 times less ozone destruction than one tonne of CFC-11. As a result of the international agreement, the hole in the antarctic ozone layer is slowly recovering. [5] Climate projections suggest that the ozone layer will return to 1980 levels between 2050 and 2070. [6] [7] [8] The success of the Montreal Protocol is due to its effective burden-sharing and proposed solutions, which have helped to mitigate regional conflicts of interest in relation to gaps in the global regulatory approach of the Kyoto Protocol. [9] However, global regulation was already in place before a scientific consensus was reached, and the general public was convinced of the possible immediate risks of the ozone layer. [10] [11] The Montreal Protocol is also expected to have an impact on human health. A 2015 U.S.
report by the Environmental Protection Agency estimates that protecting the ozone layer under the treaty will prevent 280 million cases of skin cancer, 1.5 million deaths from skin cancer, and 45 million cataracts in the United States. [50] Strahan, S. E. and Douglass, A. R. (2018). Decrease in Antarctic ozone depletion and lower stratospheric chlorine, determined from Aura Microwave Limb Sounder observations. Geophysical Research Letters, 45(1), 382-390. Available at agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017GL074830.
The original Montreal Protocol, signed in 1987, was the first step in international efforts to protect stratospheric ozone. Under the original Montreal Protocol (1987), industrialized countries were obliged to start phasing out CFCs in 1993 and to reduce their consumption by 20 per cent by 1994 compared to 1986 and by 50 per cent in 1998. In addition, developed countries have had to freeze their production and consumption of halons from their 1986 levels. After the signing of the Montreal Protocol, new data showed more severe than expected damage to the ozone layer. Hydrochlorofluorocarbons, commonly known as HCFCs, are a group of artificial compounds that contain hydrogen, chlorine, fluorine and carbon. They are found nowhere in nature. HCFC production began to increase after countries agreed in the 1980s to phase out the use of CFCs, which destroy the ozone layer. Like CFCs, HCFCs are used for cooling, aerosol fuels, foam production and air conditioning. However, unlike CFCs, most HCFCs are degraded in the lowest part of the atmosphere and pose a much lower risk to the ozone layer.
Nevertheless, despite their very low atmospheric concentrations, measured in parts per trillion (millions of millions), HCFCs are very strong greenhouse gases. On 13 January 1982, the Secretariat of the United Nations Environment Programme issued a document to the Ad Hoc Working Group (UNEP/GT.69/8) entitled “Some remarks on the elaboration of a global Framework Convention for the Protection of the Stratospheric Ozone Layer”. This article referred, inter alia, to the relevant recommendations and contributions of the ad hoc meeting of senior officials and experts in environmental law (28-6 October). November 1981 in Montevideo) (UNEP/WG.69/8, paragraphs 7, 8, 36 and 37), the Ozone Layer Coordination Committee (UNEP/WG.69/8, paragraphs 3, 8, 15 and 33) and the documents submitted by the delegations of Finland, Sweden, Switzerland and Norway (UNEP/WG.69/8, paragraphs 9, 36 and 42), including the draft International Convention for the Protection of the Stratospheric Ozone Layer (UNEP/WG.69/3). Montzka, S. A., Dutton, G. S., Yu, P., Ray, E., Portmann, R. W., Daniel, J. S., . & Nance, J.D.
(2018). An unexpected and sustained increase in global emissions of ozone-depleting CFC-11. Nature, 557(7705), 413. Available at: www.nature.com/articles/s41586-018-0106-2. The provisions of the Protocol provide, inter alia, that Parties to the Protocol shall base their future decisions on current scientific, environmental, technical and economic information assessed by the bodies of the global communities of experts. To make this contribution to the decision-making process, the progress made in understanding these issues in 1989, 1991, 1994, 1998 and 2002 was assessed by the Scientific Assessment Panel (SAP) in a series of reports entitled “Scientific Assessment of Ozone Depletion”. [18] Also in 1985, 20 countries, including most of the largest producers of CFCs, signed the Vienna Convention, which provided a framework for the negotiation of international regulations on ozone-depleting substances. [37] Following the discovery of the hole in the ozone layer by SAGE 2, it took only 18 months for a binding agreement to be reached in Montreal, Canada. The Montreal Protocol is a multilateral environmental agreement on the phase-out of ozone-depleting substances (ODS). It was ratified in 1989, just four years after the discovery of the hole in the ozone layer, and targeted chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) that remove ozone from the stratosphere.
At that time, CFCs and HCFCs were ubiquitous in household appliances such as air conditioners, refrigerators and freezers. Since the ratification of the Montreal Protocol, ozone levels in the atmosphere have recovered significantly, and in 2019, reports suggested that the hole in the ozone layer was the smallest since 1982, making the Montreal Protocol one of the most successful international treaties. .