Editing Montreal Protocol (section)

==History==
{{more citations needed section|date=September 2019}}
In the 1970s, the chemists [[Frank Sherwood Rowland]] and [[Mario Molina]], who were then at the [[University of California, Irvine]], began studying the impacts of CFCs in the Earth's atmosphere. They discovered that CFC molecules were stable enough to remain in the atmosphere until they got up into the middle of the [[stratosphere]] where they would finally (after an average of 50–100 years for two common CFCs) be broken down by [[ultraviolet radiation]] releasing a [[chlorine]] atom. Rowland and Molina then proposed that these chlorine atoms might be expected to cause the breakdown of large amounts of ozone (O<sub>3</sub>) in the stratosphere. Their argument was based upon an analogy to contemporary work by [[Paul J. Crutzen]] and Harold Johnston, which had shown that nitric oxide (NO) could catalyze the destruction of ozone. (Several other scientists, including [[Ralph Cicerone]], [[Richard Stolarski]], Michael McElroy, and Steven Wofsy had independently proposed that chlorine could catalyze ozone loss, but none had realized that CFCs were a potentially large source of chlorine.) Crutzen, Molina and Rowland were awarded the 1995 [[Nobel Prize for Chemistry]] for their work on this problem.

The environmental consequence of this discovery was that, since stratospheric ozone absorbs most of the ultraviolet-B (UV-B) radiation reaching the surface of the planet, depletion of the ozone layer by CFCs would lead to an increase in UV-B radiation at the surface, resulting in an increase in skin cancer and other impacts such as damage to crops and to marine phytoplankton.

The Rowland-Molina hypothesis was strongly disputed by representatives of the aerosol and halocarbon industries. The chair of the board of [[DuPont]] was quoted as saying that ozone depletion theory is "a science fiction tale...a load of rubbish...utter nonsense". [[Robert Abplanalp]], the president of Precision Valve Corporation (and inventor of the first practical aerosol spray can valve), wrote to the Chancellor of UC Irvine to complain about Rowland's public statements (Roan, p.&nbsp;56.)

After publishing their pivotal paper in June 1974, Rowland and Molina testified at a
hearing before the U.S. House of Representatives in December 1974. As a result, significant funding was made available to study various aspects of the problem and to confirm the initial findings. In 1976, the U.S. [[United States National Academy of Sciences|National Academy of Sciences]] (NAS) released a report that confirmed the scientific credibility of the ozone depletion hypothesis.<ref name="NAS1976">{{cite book | last = National Academy of Sciences | author-link = United States National Academy of Sciences | title = Halocarbons, effects on stratospheric ozone | year = 1976 | location = Washington, DC | url = https://nap.nationalacademies.org/read/19978 | isbn = 0-309-02532-X}}</ref> NAS continued to publish assessments of related science for the next decade.

In 1982, representatives from 24 countries met in Stockholm, Sweden to decide on a "Global Framework Convention for the Protection of the Ozone Layer." The following year, a group of countries, including the United States, Canada, the Nordic Countries, and Switzerland, proposed a worldwide ban on "nonessential" uses of CFCs in spray cans.<ref name="Benedick 1989 43–50">{{Cite journal |last=Benedick |first=Richard Elliot |date=1989 |title=Ozone Diplomacy |url=https://www.jstor.org/stable/43309418 |journal=Issues in Science and Technology |volume=6 |issue=1 |pages=43–50 |jstor=43309418 |issn=0748-5492}}</ref>

Then, in 1985, [[British Antarctic Survey]] scientists [[Joe Farman]], [[Brian G. Gardiner (meteorologist)|Brian Gardiner]] and [[Jon Shanklin]] published results of abnormally low ozone concentrations above [[Halley Bay]] near the [[South Pole]]. They speculated that this was connected to increased levels of CFCs in the atmosphere. It took several other attempts to establish the Antarctic losses as real and significant, especially after NASA had retrieved matching data from its satellite recordings. This unforeseen phenomenon in the Antarctic, as well as NASA's scientific images of the ozone hole played an important role in the Montreal Protocol negotiations.<ref>{{cite journal | doi=10.1017/S000708742300002X | title=Satellite images as tools of visual diplomacy: NASA's ozone hole visualizations and the Montreal Protocol negotiations | year=2023 | last1=Grevsmühl | first1=Sebastian V. | last2=Briday | first2=Régis | journal=The British Journal for the History of Science | volume=56 | issue=2 | pages=247–267 | pmid=36776108 | s2cid=256825183 | doi-access=free }}</ref> The impact of these studies, the metaphor 'ozone hole', and the colorful visual representation in a time lapse animation proved shocking enough for negotiators in Montreal, Canada to take the issue seriously.<ref>Grundmann, Reiner, Transnational Environmental Policy: Reconstructing Ozone, London: Routledge, {{ISBN|0-415-22423-3}}</ref>
[[File:Satellite map of ozone about Antartica.png|thumb|TOMS satellite map showing the total ozone above the Antarctic region. Taken on 1 October 1983 (NASA)]]
[[File:Subscriptions to the Montreal Protocol by region, OWID.svg|thumb|Parties subscribed to the Montreal Protocol by region, 1987-2013]]
Also in 1985, 20 nations, including most of the major CFC producers, signed the [[Vienna Convention for the Protection of the Ozone Layer|Vienna Convention]], which established a framework for negotiating international regulations on ozone-depleting substances.<ref>{{Cite web|url=https://ozone.unep.org/treaties/vienna-convention|website=ozone.unep.org|access-date=2020-04-22|title=The Vienna Convention for the Protection of the Ozone Layer &#124; Ozone Secretariat }}</ref> After the discovery of the ozone hole 
by SAGE 2 it only took 18 months to reach a binding agreement in Montreal, Canada. [[Mostafa Kamal Tolba]], the head of the [[United Nations Environment Programme|UNEP]] at the time, was considered the "father of the Montreal Protocol" for his role in bringing the nations together for an agreement.<ref>{{Cite web |title=Dr. Mostafa Tolba, Father of Montreal Protocol, Dies at 93 - IGSD |date=29 March 2016 |url=https://www.igsd.org/dr-mostafa-tolba-father-of-montreal-protocol-dies-at-93/ |access-date=2023-09-28 |language=en-US}}</ref>

In 1986, an assessment spearheaded by NASA and sponsored by the United Nationals Environment Program, the [[World Meteorological Organization]], and various other organizations concluded that continued CFC emissions at the 1980 rate would "reduce global average ozone by about 9 percent by the latter half of the century." Based on these figures, the U.S. [[United States Environmental Protection Agency|Environmental Protection Agency]] estimated that in the United States alone there could be "over 150 million new cases of skin cancer among people currently alive and born by the year 2075, resulting in over 3 million deaths."<ref name="Benedick 1989 43–50"/>

The CFC industry continued pushing back against regulation as late as 1986, when the Alliance for Responsible CFC Policy (an association representing the CFC industry founded by [[DuPont]]) was still arguing that the science was too uncertain to justify any action. In 1987, DuPont testified before the US Congress that "We believe there is no imminent crisis that demands unilateral regulation."<ref name=Doyle1991>{{cite news|last1=Doyle|first1=Jack|title=DuPont's Disgraceful Deeds: The Environmental Record of E.I. DuPont de Nemour|url=http://www.multinationalmonitor.org/hyper/issues/1991/10/doyle.html|journal=The Multinational Monitor|volume=12|issue=10|access-date=8 September 2014|date=October 1991}}</ref> And even in March 1988, Du Pont Chair Richard E. Heckert would write in a letter to the United States Senate, "we will not produce a product unless it can be made, used, handled and disposed of safely and consistent with appropriate safety, health and environmental quality criteria. At the moment, scientific evidence does not point to the need for dramatic CFC emission reductions. There is no available measure of the contribution of CFCs to any observed ozone change..."<ref name=Greenpeace1997>{{cite web|title=Du Pont: A Case Study in the 3D Corporate Strategy|url=http://archive.greenpeace.org/ozone/greenfreeze/moral97/6dupont.html|publisher=Greenpeace|access-date=8 September 2014|archive-url=https://web.archive.org/web/20120406093303/http://archive.greenpeace.org/ozone/greenfreeze/moral97/6dupont.html|archive-date=2012-04-06|year=1997}}</ref>

In an unexpected policy change, however, the Alliance for Responsible CFC Policy issued a statement in 1986 declaring that "large future increases...in CFCs...would be unacceptable to future generations," and that it would be "inconsistent with [industry] goals...to ignore the potential for risk to future generations." Three months before the protocol negotiations began, U.S. industry announced its support for new international controls on CFCs.<ref name="Benedick 1989 43–50"/>