tag:theconversation.com,2011:/africa/topics/saving-the-ozone-3785/articlesSaving the ozone – The Conversation2012-09-18T23:34:43Ztag:theconversation.com,2011:article/92482012-09-18T23:34:43Z2012-09-18T23:34:43ZSetting a good example: Australia and the ozone layer<figure><img src="https://images.theconversation.com/files/15516/original/bd5vkgpk-1347845622.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Australia had a special interest in fixing the ozone hole.</span> <span class="attribution"><span class="source">Jon Tunley</span></span></figcaption></figure><p><em><a href="https://theconversation.com/topics/saving-the-ozone">SAVING THE OZONE</a>: The final part our series exploring the Montreal Protocol on Substances that Deplete the Ozone Layer – dubbed “the world’s most successful environmental agreement” – looks at Australians who’ve helped protect the atmosphere.</em></p>
<p>Australia has always been at the forefront of efforts to protect the ozone layer.</p>
<p>There are good reasons for our involvement. Protecting the stratospheric ozone layer is particularly important because of our sunny climate and outdoor lifestyle. Ozone depletion - because it allows more of the <a href="https://theconversation.com/how-does-the-ozone-layer-protect-earth-from-radiation-9206">dangerous UV</a> to reach the earth’s surface - can have a direct effect on the <a href="https://theconversation.com/saving-the-ozone-layer-saved-human-lives-9494">health of Australians</a> and on our environment. The Australian contribution to this environmental effort is also notable because it came from business, government, environment and conservation groups and the general community. It’s a good model for future environmental activity.</p>
<p>With the discovery of the ozone hole over Antarctica in 1985, Australians felt exposed and vulnerable to ozone layer depletion. We suddenly became more attuned to the environmental impact of global activities. There was also a growing realisation that Australia was one of the world’s largest per capita users of CFCs and halon.</p>
<p>These factors combined to drive Australia’s subsequent coordinated national action and international leadership on ozone protection. Scientific institutions and technical organisations and industry collaborated to phase-out the use of ozone-depleting substances in Australia. This shared commitment has been pivotal in Australia’s success in meeting its obligations under the Montreal Protocol.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/15509/original/d8wtnnxy-1347843669.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/15509/original/d8wtnnxy-1347843669.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=328&fit=crop&dpr=1 600w, https://images.theconversation.com/files/15509/original/d8wtnnxy-1347843669.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=328&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/15509/original/d8wtnnxy-1347843669.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=328&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/15509/original/d8wtnnxy-1347843669.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=412&fit=crop&dpr=1 754w, https://images.theconversation.com/files/15509/original/d8wtnnxy-1347843669.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=412&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/15509/original/d8wtnnxy-1347843669.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=412&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">To mark the 25th anniversary of the Montreal Protocol, on 13 September 2012, the Australian Government presented certificates to seven Australians who have made outstanding contributions to the phase-out of ozone depleting substances. See more at www.environment.gov.au/atmosphere/ozone/legislation/montp-25years-recognition.html.</span>
<span class="attribution"><span class="source">Andrew Tatnell</span></span>
</figcaption>
</figure>
<p>It hasn’t been just local recognition of leadership, expertise and high levels of commitment to ozone layer protection. Many Australian institutions and individuals have been recognised by the United Nations Environment Programme and the US Environmental Protection Agency for their contribution to protection of the ozone layer. We can be very proud of recognition like the following.</p>
<ul>
<li><p>In 2008 the Australian Government was acclaimed for reducing the use in the Asia-Pacific region of methyl bromide – an ozone depleting substance widely used in agricultural and quarantine fumigation.</p></li>
<li><p>The Australian Government received recognition for helping developing countries phase out ozone depleting substances, and for establishing the National Halon Bank to collect, reclaim and reuse (and where necessary, destroy) halon for fire-suppression uses in Australia. This bank still operates today and plays an important role in providing halon for essential uses in shipping and aviation.</p></li>
<li><p>The Victorian Government received an award in 2007 when its Methyl Bromide Research Scheme evaluated alternatives to methyl bromide and supported Australia’s efforts to phase out methyl bromide.</p></li>
<li><p>Together with Strawberries Australia and AUSVEG, the Victorian Government received an ozone protection award for phasing out methyl bromide use in Australian soils.</p></li>
<li><p>The Halon Essential Uses Panel, initially established by the Victorian EPA, was recognised in 1992 for limiting the sale of halon in Australia to essential uses only.</p></li>
</ul>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/15514/original/tdgz9xyz-1347845201.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/15514/original/tdgz9xyz-1347845201.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/15514/original/tdgz9xyz-1347845201.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/15514/original/tdgz9xyz-1347845201.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/15514/original/tdgz9xyz-1347845201.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/15514/original/tdgz9xyz-1347845201.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/15514/original/tdgz9xyz-1347845201.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Australia has done some great work reducing halon use.</span>
<span class="attribution"><span class="source">boviate/Flickr</span></span>
</figcaption>
</figure>
<p>Australian scientists have been honoured for their contributions to ozone protection through their work on the Montreal Protocol’s scientific and technical advisory bodies, the Scientific Assessment Panel and the Technology and Economic Assessment Panel:</p>
<ul>
<li><p><a href="https://theconversation.com/profiles/paul-fraser-13303">Dr Paul Fraser</a> from the CSIRO, for his monitoring of ozone-depleting substances in the Southern Hemisphere and archival of air samples for use by research organisations around the world.</p></li>
<li><p>Dr Jonathan Banks, formerly of CSIRO, for his work on developing and promoting alternatives to methyl bromide.</p></li>
<li><p>Dr Ian Porter, from the Victorian Department of Primary Industries, also for his work on methyl bromide alternatives.</p></li>
<li><p>Dr Helen Tope, formerly from the Victorian EPA, for her work on alternatives to CFCs in metered dose inhalers.</p></li>
<li><p><a href="https://theconversation.com/profiles/ian-rae-13036">Dr Ian Rae</a> for helping countries use alternatives to ozone depleting substances for industrial and laboratory uses.</p></li>
</ul>
<p>Non-government organisations have also received international recognition:</p>
<ul>
<li><p>Nordiko Quarantine Systems, for developing a process to recapture methyl bromide used for fumigation in shipping containers and ensure its safe disposal.</p></li>
<li><p>Refrigerant Reclaim Australia, an industry-funded environmental trust established to recover, reclaim and destroy ozone depleting substances and their substitutes, for its innovative approach to product stewardship.</p></li>
<li><p>the Australian Cancer Council in 2007 for its pioneering “slip, slop, slap” campaign, which focused public attention on the dangers of high exposure to UV radiation and the need to protect the ozone layer.</p></li>
<li><p>the then Association of Fluorocarbon Consumers and Manufacturers of Australia for their early support of phasing out chlorofluorocarbons (CFCs) in Australia.</p></li>
<li><p>Woolworths for its pioneering work in phasing out the use of CFCs in their refrigeration systems and in promoting alternatives.</p></li>
</ul>
<p>As we celebrate the 25th anniversary of the Montreal Protocol, it is fitting that we reflect on the fact that Australia’s success at phasing out its use of ozone-depleting substances is not the result of one government agency or one individual. Rather, it is the result of many dedicated individuals from a wide range of government, industry and scientific and technical organisations using their expertise to work together for a common purpose.</p>
<p><em>This article was co-authored by Annie Gabriel, who works for the Department of Sustainability, Environment, Water, Population and Communities on ozone protection policy. She has a BA from the ANU and a Graduate Certificate in Public Policy from Flinders University.</em></p>
<p><em><a href="https://theconversation.com/topics/saving-the-ozone">Read more</a> on the Montreal Protocol’s 25th anniversary.</em></p><img src="https://counter.theconversation.com/content/9248/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ian Rae does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>SAVING THE OZONE: The final part our series exploring the Montreal Protocol on Substances that Deplete the Ozone Layer – dubbed “the world’s most successful environmental agreement” – looks at Australians…Ian Rae, Honorary Professorial Fellow, Faculty of Arts, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/91992012-09-17T20:39:48Z2012-09-17T20:39:48ZMeasuring the missing molecules: a history of overseeing ozone<figure><img src="https://images.theconversation.com/files/15106/original/7dvz2nb8-1346895941.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Around 90% of ozone is located in the lower stratosphere (beginning at a height of between 10-16 km above the ground).</span> <span class="attribution"><span class="source">Flickr/NASA Earth Observatory</span></span></figcaption></figure><p><em><a href="https://theconversation.com/topics/saving-the-ozone">SAVING THE OZONE</a>: Part eight in our series exploring the Montreal Protocol on Substances that Deplete the Ozone Layer – dubbed “the world’s most successful environmental agreement” – looks at how we measure ozone’s ups and downs.</em></p>
<p>In the 1980s, scientists realised Earth’s ozone layer was diminishing, endangering the health of humans and other species. But they would never have known this if not for an 80-year-old instrument still in use today.</p>
<p>The <a href="http://www.bom.gov.au/climate/glossary/ozone.shtml#howmeasured">Dobson spectrophotometer</a> (or simply “the Dobson”) was developed by Gordon Dobson at Oxford University in the 1920s. It allowed for the first time a quick but very accurate determination of Total Column Ozone at a given location.</p>
<p>Essentially, the Dobson works by comparing the intensity of light at two pairs of wavelengths. For each pair, one wavelength is much more strongly absorbed by ozone in the atmosphere than the other. By comparing the ratios of the intensities, the total amount of ozone overhead can be calculated. The unit of measurement for Column Ozone is named the “Dobson Unit” (DU), in honour of Gordon Dobson.</p>
<p>It is this measurement which shows the diminishing levels of ozone in the stratosphere at specific locations.</p>
<h2>The Dobson in Australia</h2>
<p>In 1936, three Australian organisations placed a combined order for three of the new instruments at a cost of £400 each – the Bureau of Meteorology, Mt Stromlo Observatory and the Council for Scientific and Industrial Research (CSIR) Radio Research Board. Although the Dobsons were manufactured and tested, none began operational use in Australia until after the Second World War.</p>
<p>It wasn’t until <a href="http://www.wmo.int/pages/mediacentre/documents/Int.GeophysicalYear.pdf">The International Geophysical Year of 1957</a> that a concerted global effort was made to establish a worldwide Dobson network. Australia established ongoing monitoring programs at Brisbane, Melbourne and the <a href="https://maps.google.com.au/maps?hl=en&q=macquarie+island&ie=UTF-8&authuser=0">sub-Antarctic Macquarie Island</a>. These programs continue to the present day.</p>
<p>On the January 1 1983, the Bureau of Meteorology assumed full responsibility for the Australian ozone network (now including Darwin as well as the other three locations). The Bureau’s network Dobsons are all still fully manual in operation.</p>
<p>Despite their age, Dobsons remain in wide use across the world and continue to form the backbone of the surface-based component of the global ozone monitoring network. Although modern and more capable instruments have been developed in the 80 years since its creation, the Dobson has in its favour, as well as continuity with long standing measurement programs, great stability and operational reliability.</p>
<p>As with any long-term monitoring program, in order to detect small changes over long periods of time, questions of calibration and consistency of operation become crucial. Unfortunately in the case of Dobsons, standardisation was only really put on a solid footing in 1977 when the <a href="http://www.wmo.int/pages/prog/arep/gaw/ozone/index.html">World Meteorological Organisation</a> designated a World Standard Dobson and a number of Regional Standards. From this time on each Dobson became traceable to the Regional Standard and thus to the World Standard. The Bureau operates the Standard Dobson for the South-West Pacific Region.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/14815/original/qspn525p-1346305529.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/14815/original/qspn525p-1346305529.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/14815/original/qspn525p-1346305529.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/14815/original/qspn525p-1346305529.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/14815/original/qspn525p-1346305529.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/14815/original/qspn525p-1346305529.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/14815/original/qspn525p-1346305529.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Bureau observer Janelle Inkster makes a Dobson observation at Macquarie Island.</span>
<span class="attribution"><span class="source">Ashleigh Wilson</span></span>
</figcaption>
</figure>
<h2>Ozone over Australia</h2>
<p>At all of the Australian locations, ozone follows a distinct cycle over the course of each year, increasing in winter and spring and then decreasing over summer through to autumn. The size of the increase however is much greater with increasing distance from the tropics - the typical annual range expressed as monthly mean values over the last decade have been around 240 to 260 Dobson units at Darwin, 260 to 310 DU at Brisbane, 270 to 340 DU at Melbourne and 290 to 400 DU at Macquarie. For comparison, in Antarctica during springtime total ozone can <a href="https://theconversation.com/explainer-what-is-the-antarctic-ozone-hole-and-how-is-it-made-9202">drop below 100 DU</a>.</p>
<p>Superimposed upon the annual cycle there is considerable day-to-day variability (again more so in the mid-latitudes than the tropics or subtropics), primarily due to the effect of passing weather systems. Total ozone will often increase or decrease by 50 DU within the space of a day or two. Individual readings on a given day can therefore be much higher or lower than the monthly mean values.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/14816/original/h8yb8bjh-1346305587.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/14816/original/h8yb8bjh-1346305587.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=409&fit=crop&dpr=1 600w, https://images.theconversation.com/files/14816/original/h8yb8bjh-1346305587.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=409&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/14816/original/h8yb8bjh-1346305587.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=409&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/14816/original/h8yb8bjh-1346305587.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=514&fit=crop&dpr=1 754w, https://images.theconversation.com/files/14816/original/h8yb8bjh-1346305587.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=514&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/14816/original/h8yb8bjh-1346305587.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=514&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Figure 1 – Monthly mean Total Column Ozone values for Melbourne 1978-2012, smoothed by a 132 month running mean to remove the effects of the annual cycle and long-term periodic influences. (The first and last five years are not shown due to the smoothing).</span>
</figcaption>
</figure>
<p>Figure 1 shows that the ozone trend is broadly consistent (in reverse) with the <a href="https://theconversation.com/what-are-ozone-depleting-substances-9203">trend in ozone depleting substances</a>, decreasing steadily through the 1980s and early 1990s, followed by a steadying and finally a small increase in recent years. </p>
<h2>Two natural phenomena</h2>
<p>For year to year variations in ozone, two large-scale natural phenomena are particularly important over mid-latitudes: the 11-year Solar Cycle and the so-called Quasi-Biennial Oscillation (QBO).</p>
<p>The <a href="http://en.wikipedia.org/wiki/Solar_cycle">Solar Cycle</a> refers to the approximately cyclical variation in various processes taking place in the sun, first discovered by astronomers noting patterns in the number of sunspots. The amount of solar UV flux received by Earth is modulated by this cycle, and this directly affects the amount of ozone produced in the atmosphere. This may also indirectly influence ozone by modifying the circulation. The effect of the solar cycle over ozone in summer over Melbourne, for example, is about 5 DU.</p>
<p>The Quasi-Biennial Oscillation (<a href="http://en.wikipedia.org/wiki/Quasi-biennial_oscillation">QBO</a>) refers to the reversal in direction of the mean east-west wind in the tropical stratosphere. It is observed to take place about every 27-29 months (hence the name “quasi-biennial”). Although not all the mechanisms are fully resolved, the QBO appears to have a very significant influence on the stratosphere at latitudes outside the tropics as well. The phase of the QBO in a given year affects springtime ozone values by up to 20 DU.</p>
<p>Other factors which have been shown to influence ozone levels include debris from volcanic eruptions injected into the stratosphere, and various dynamic influences including the El Niño–Southern Oscillation (<a href="http://en.wikipedia.org/wiki/El_Ni%C3%B1o%E2%80%93Southern_Oscillation">ENSO</a>).</p>
<p><em><a href="https://theconversation.com/topics/saving-the-ozone">Read more</a> on the Montreal Protocol’s 25th anniversary.</em></p><img src="https://counter.theconversation.com/content/9199/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Matt Tully is Supervisor of the Global Atmosphere Watch and Data Delivery group at the Bureau of Meteorology. The Bureau presently operates under the authority of the Meteorology Act 1955, which requires it to report on the state of the atmosphere and oceans in support of Australia's social, economic, cultural and environmental goals. Matt Tully does not consult to, own shares in or receive funding from any company or organisation that would benefit from this article, and has no relevant affiliations.</span></em></p>SAVING THE OZONE: Part eight in our series exploring the Montreal Protocol on Substances that Deplete the Ozone Layer – dubbed “the world’s most successful environmental agreement” – looks at how we measure…Matt Tully, Supervisor Global Atmosphere Watch & Data Delivery, Australian Bureau of MeteorologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/94942012-09-16T20:25:47Z2012-09-16T20:25:47ZSaving the ozone layer saved human lives<figure><img src="https://images.theconversation.com/files/15368/original/hwqcfg6p-1347412569.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Reduced ozone means increased UV radiation, and that leads to skin cancer.</span> <span class="attribution"><span class="source">Tracey Lawson</span></span></figcaption></figure><p><em><a href="https://theconversation.com/topics/saving-the-ozone">SAVING THE OZONE</a>: Part seven in our series exploring on the Montreal Protocol on Substances that Deplete the Ozone Layer – dubbed “the world’s most successful environmental agreement” – explains how the protocol reduced skin cancer.</em></p>
<p>The Montreal Protocol for the protection of the stratospheric ozone layer is <a href="https://theconversation.com/saving-the-ozone-layer-why-the-montreal-protocol-worked-9249">widely hailed</a> as the most successful international agreement on environmental regulation. But it didn’t just protect “the environment”, it also saved the lives of thousands of human beings. </p>
<p>Adopted in 1987, the protocol and its Amendments and Adjustments have successfully reduced the emissions of ozone-depleting substances (ODSs). In the lower atmosphere, many ODSs are chemically inactive, but in the stratosphere (above ~17 km) they break up under intense ultraviolet radiation. This liberates their halogen atoms which causes chemical ozone destruction. The most dramatic consequence is the <a href="https://theconversation.com/explainer-what-is-the-antarctic-ozone-hole-and-how-is-it-made-9202">Antarctic ozone hole</a>, discovered in 1985. </p>
<p>Also at middle latitudes, such as over Australia, a substantial thinning of the ozone layer has been observed. The thinning of the ozone layer causes an <a href="https://theconversation.com/how-does-the-ozone-layer-protect-earth-from-radiation-9206">increase of ultraviolet (UV) radiation</a> at the Earth’s surface, which is linked to the occurrence of skin cancer. Australia has one of the highest rates of skin cancer worldwide.</p>
<p>A recent study which appeared in the journal <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1751-1097.2012.01223.x/abstract?systemMessage=Wiley+Online+Library+will+be+disrupted+on+15+September+from+10%3A00-12%3A00+BST+%2805%3A00-07%3A00+EDT%29+for+essential+maintenance">Photochemical and Photobiological Sciences</a> quantifies how much the Montreal Protocol may have reduced <a href="https://theconversation.com/topics/skin-cancer">skin cancer</a>. The study uses two types of models. The first are two chemistry-climate models (CCMs). They combine representations of atmospheric physics with formulations of stratospheric ozone chemistry. The second is a medical risk model which translates the projected surface UV intensities inferred from the CCMs into rates of skin cancer. </p>
<p>These models are then used to simulate two projections. One, of the ozone layer in compliance with the Montreal Protocol. Second, the alternative: the protocol’s absence and market-driven growth of ozone depleting substances.</p>
<p>Fed into the CCMs, these two scenarios produce dramatically different projections of surface UV, which the authors then use to infer skin cancer occurrences. This latter step is complicated by the time lag of several decades between exposure of a young individual to UV and the occurrence of skin cancer much later in life.</p>
<p>Putting all the available information together, the authors suggest that the Montreal Protocol will prevent two million cases per annum (or 16% of cases that would have occurred) of skin cancer worldwide by 2030. Beyond 2030, in the no-Montreal Protocol scenario, the rate of occurrence of skin cancer would continue to grow dramatically. </p>
<p>Eight geographical regions are investigated, including North-Eastern Australia (Queensland). They find that in Queensland, up to 200 additional cases of skin cancer per million people per year are expected to occur as a result of the past and projected ozone depletion. This is in contrast to what would have occurred without the man-made damage to the ozone layer.</p>
<p>This represents the largest additional occurrence of skin cancer due to ozone depletion of any of the eight regions studied, but still only amounts to a few percent of the total rate of skin cancer occurrence in Queensland. This is because there are other important factors that make up Australia’s skin cancer risk. These are unrelated to ozone depletion, and include predominantly fair skin type and lifestyle. </p>
<p>If we had let ozone depleting substances increase, there would have been 1100-1500 additional skin cancer cases per million people per year in parts of Australia in the year 2030.</p>
<p>The study is the first of its kind to quantify the health benefit of the Montreal Protocol for skin cancer. The Montreal Protocol essentially contained the risk of skin cancer due to man-made ozone depletion to a few percent of additional occurrences. Had no action been taken, by 2030 the skin cancer risk would have increased by much more, not to speak of the decades beyond. </p>
<p><em><a href="https://theconversation.com/topics/saving-the-ozone">Read more</a> on the Montreal Protocol’s 25th anniversary.</em></p><img src="https://counter.theconversation.com/content/9494/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter Braesicke receives funding from NERC and ESA funds to work on stratospheric ozone and its past and future development. He does not receive company sponsorship.</span></em></p><p class="fine-print"><em><span>Olaf Morgenstern does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>SAVING THE OZONE: Part seven in our series exploring on the Montreal Protocol on Substances that Deplete the Ozone Layer – dubbed “the world’s most successful environmental agreement” – explains how the…Olaf Morgenstern, Chemistry-climate modeller, atmospheric scientist, National Institute of Water and Atmospheric ResearchPeter Braesicke, Researcher, National Centre for Atmospheric Science, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/92002012-09-15T00:04:31Z2012-09-15T00:04:31ZWhat Venus has taught us about protecting the ozone layer<figure><img src="https://images.theconversation.com/files/15381/original/65jpt2gw-1347426242.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Understanding Venus' atmosphere helps us understand Earth’s past, present, and a potential future.</span> <span class="attribution"><span class="source">Keith Mosley</span></span></figcaption></figure><p><em><a href="https://theconversation.com/topics/saving-the-ozone">SAVING THE OZONE</a>: Part six in our series exploring the Montreal Protocol on Substances that Deplete the Ozone Layer – dubbed “the world’s most successful environmental agreement” – looks at the atmosphere of Venus and what it means for us on earth.</em></p>
<p>In June 2012, Venus <a href="https://theconversation.com/topics/transit-of-venus">passed in front of the Sun</a>. This won’t happen again until 2117. The transit of Venus played a well-recognised, <a href="https://theconversation.com/transit-of-venus-a-tale-of-two-expeditions-7246">significant role</a> in British exploration of Australia. But Venus has also played less-well-known roles in understanding the chemistry in the Earth’s atmosphere. Venus helped us recognise that chlorofluorocarbons (CFCs) can decompose stratospheric ozone (O₃).</p>
<p>Mario Molina and Sherry Rowland from the University of California, Irvine, shared the <a href="http://www.nobelprize.org/nobel_prizes/chemistry/laureates/1995/press.html">1995 Nobel Prize for Chemistry</a> “for their work in atmospheric chemistry, particularly concerning the formation and decomposition of ozone”. Their seminal contribution was captured in an article in <em>Nature</em> in 1974, which identified the threat that CFCs posed to Earth’s ozone layer.</p>
<p>The Swedish Academy noted that Molina and Rowland’s work built directly on two important contributions by other researchers. </p>
<p>One was James Lovelock, who during 1971-73 showed that CFC gases had spread throughout the global atmosphere. And from 1972-74, Richard Stolarski and Ralph Cicerone from the University of Michigan examined the impact of the space shuttle on the stratosphere. They showed that free chlorine atoms (Cl) produced from the breakdown of hydrogen chloride (HCl) emitted from the shuttle’s solid rocket boosters could catalytically convert O₃ to molecular oxygen (O₂).</p>
<p>In parallel, Michael McElroy and Steven Wofsy from Harvard University were studying catalytic destruction of O₃ by chlorine and nitrogen gases on Earth, and McElroy’s group and Ronald Prinn at MIT were studying the broader impact of chlorine on another planet’s atmospheric chemistry – Venus.</p>
<p>By 1970, scientists knew there were five gases in the atmosphere of Venus – carbon dioxide (CO₂) (the vast majority of the atmosphere), water vapour (H₂O), carbon monoxide (CO), hydrogen chloride (HCl), and hydrogen fluoride (HF). </p>
<p>Carbon dioxide, like O₃, is not stable against the intense ultraviolet (UV) light present in the uppermost parts of a planetary atmosphere. With the vertical mixing that occurs in an atmosphere, an initially pure CO₂ atmosphere can be expected to decompose. This will produce a few percent each of carbon monoxide (CO) and molecular oxygen (O₂) in less than a thousand years. So why does CO₂ remain stable on Venus?</p>
<p>Understanding the stability of CO₂ on Venus helps us understand the early Earth’s atmosphere. It also tells us about planets similar to Earth orbiting other stars. More generally, studying chemistry on Venus can help identify chemistry we did not know was occurring on Earth, as happened for CFCs, chlorine chemistry, and ozone. </p>
<p>Scientists thought CO₂ might be stabilised on Venus by chemical reactions involving hydrogen and chlorine gases. Hydrogen chemistry is critical for understanding the atmosphere on Mars. Trace amounts of water on Mars are split apart by UV light to produce reactive hydrogen gases. But hydrogen chemistry alone couldn’t explain the stability of CO₂ in Venus’ denser atmosphere. </p>
<p>Hydrogen chloride (HCl) can be split apart more readily than water by UV light in a dense CO₂ atmosphere. Hydrogen chloride is decomposed by UV light at longer wavelengths which are not absorbed by CO₂. So the atmospheric chemistry models developed for Venus in 1971-73 by Ronald Prinn, Michael McElroy, and McElroy’s students explored how HCl chemistry could make CO₂ stable.</p>
<p>McElroy’s group focused on HCl as a source for reactive hydrogen species. Prinn examined the potential for Cl, ClO, and ClO₂ to react with CO and, thus, produce CO₂ via catalytic cycles similar to those which destroy O₃ in Earth’s stratosphere. The chlorine catalytic cycles now believed to dominate production of CO₂ on Venus were not proposed until the early 1980s and experimentally verified in the early 2000s.</p>
<p>O₃ chemistry was not a primary focus for this early work on Venus as there were no observations at the time of O₃ on Venus. However, the potential for catalytic conversion of odd oxygen (O and O₃) to O₂ by chlorine gases was noted before its importance for the Earth’s stratosphere was fully recognised.</p>
<p>Similar parallels can be drawn between other studies of Venus and Earth. For example, production of sulphuric acid (H₂SO₄) from carbonyl sulfide (OCS) was examined in Venus atmospheric chemistry models several years before the same reactions were found to be important in Earth’s stratosphere. Also, the first versions of key instruments still used by Earth-orbiting meteorological satellites were designed for NASA’s <em>Mariner 2</em> spacecraft, which flew past Venus in 1962.</p>
<p>Ozone and chlorine monoxide (ClO) have only recently (2011 and 2012, respectively) been measured on Venus. These observations - and the chlorine catalytic chemistry that has been studied to understand the Earth’s ozone layer - may finally help resolve what catalytic chemistry keeps CO₂ stable on Venus. Despite several decades of research, this question still hasn’t been answered.</p>
<p><strong>References</strong></p>
<p>Anderson and Sarma, Protecting the Ozone Layer: The United Nations History, Earthscan Publications Ltd, 2002, pp 6-8</p>
<p>Kowalok, Environment 35, 12-20+35-38, 1993</p>
<p>Stolarski and Cicerone, Canadian Journal of Chemistry 52, 1610, 1974</p>
<p>Wofsy and McElroy, Canadian Journal of Chemistry 52, 1582, 1974</p>
<p><em><a href="https://theconversation.com/topics/saving-the-ozone">Read more</a> on the Montreal Protocol’s 25th anniversary.</em></p><img src="https://counter.theconversation.com/content/9200/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Frank Mills has received funding from the Australian Research Council and the National Aeronautics and Space Administration.</span></em></p>SAVING THE OZONE: Part six in our series exploring the Montreal Protocol on Substances that Deplete the Ozone Layer – dubbed “the world’s most successful environmental agreement” – looks at the atmosphere…Frank Mills, Research Scientist at Space Science Institute and Fellow, Research School of Physics and Engineering and The Fenner School of Environment and Society, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/94042012-09-13T20:29:15Z2012-09-13T20:29:15ZThe Antarctic ozone hole and climate change: an anniversary worth celebrating<figure><img src="https://images.theconversation.com/files/15174/original/5g95jr35-1346983104.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Is there a relationship between the ozone hole over Antarctica and the global climate?</span> <span class="attribution"><span class="source">AAP/Dean Lewins</span></span></figcaption></figure><p><em><a href="https://theconversation.com/topics/saving-the-ozone">SAVING THE OZONE</a>: Part five in our series exploring the Montreal Protocol on Substances that Deplete the Ozone Layer – dubbed “the world’s most successful environmental agreement” – explores the parallels between saving the ozone and fighting climate change.</em></p>
<p>Since the discovery of the Antarctic ozone hole more than 20 years ago, scientists have shown that there are no direct links between global warming and the ozone hole. They are due to quite different processes associated with human activities - increasing greenhouse gas emissions on one hand and increasing release of ozone-depleting chemicals on the other.</p>
<p>There are a number of common misconceptions about connections between the two, such as the ozone hole allowing more sunshine in to heat the surface and cause global warming. Scientists have tried to combat these misconceptions through more effective communication of the cause of ozone depletion and the cause of global warming.</p>
<p>However, the climate system is very complex, with connections between many different parts. Hence, it should come as no surprise to hear that there are some <em>indirect</em> links between the Antarctic ozone hole and changes in surface weather and climate.</p>
<p>Ozone <a href="https://theconversation.com/how-does-the-ozone-layer-protect-earth-from-radiation-9206">absorbs solar ultraviolet radiation</a>, warming the stratosphere. The formation of the ozone hole means less UV radiation is absorbed, cooling the stratosphere over Antarctica in spring and summer. This cooling leads to stronger westerly winds in the upper atmosphere, as well as stronger westerly winds in the lower atmosphere in late spring and summer.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/15167/original/q299g2dd-1346981595.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/15167/original/q299g2dd-1346981595.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=418&fit=crop&dpr=1 600w, https://images.theconversation.com/files/15167/original/q299g2dd-1346981595.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=418&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/15167/original/q299g2dd-1346981595.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=418&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/15167/original/q299g2dd-1346981595.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=525&fit=crop&dpr=1 754w, https://images.theconversation.com/files/15167/original/q299g2dd-1346981595.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=525&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/15167/original/q299g2dd-1346981595.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=525&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The climate system is complex, meaning that the ozone hole does indirectly alter the surface temperature and climate of the Earth.</span>
<span class="attribution"><span class="source">WMO/UNEP Scientific Assessment of Ozone Depletion 2010</span></span>
</figcaption>
</figure>
<p>These stronger winds encircling Antarctica have a number of impacts on the surface climate. They lead to reduced heat transfer from lower latitudes, making most of Antarctica cooler than it would otherwise have been but warming the Antarctic Peninsula (the part that sticks up towards South America).</p>
<p>They also lead to three other changes: in Southern Ocean currents; in the gas exchanges between the Southern Ocean and the atmosphere; and in the expansion of sea ice extent.</p>
<p>All of these changes have been observed and modelled as responses to the ozone hole, indicating that there really is an indirect link between surface climate change and the Antarctic ozone hole.</p>
<p>There is a second connection between global warming and ozone depletion. Ozone-depleting chemicals are also very potent greenhouse gases. The reduction in emissions of ozone-depleting chemicals due to the establishment of the Montreal Protocol 25 years ago has been substantial. Without this reduction, global warming would have accelerated even more. </p>
<p>In fact, the reduction in greenhouse gases due to the Montreal Protocol is five times larger than the reduction in greenhouse gases achieved through the Kyoto Protocol.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/15188/original/3ydtck2v-1346996852.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/15188/original/3ydtck2v-1346996852.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=446&fit=crop&dpr=1 600w, https://images.theconversation.com/files/15188/original/3ydtck2v-1346996852.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=446&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/15188/original/3ydtck2v-1346996852.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=446&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/15188/original/3ydtck2v-1346996852.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=560&fit=crop&dpr=1 754w, https://images.theconversation.com/files/15188/original/3ydtck2v-1346996852.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=560&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/15188/original/3ydtck2v-1346996852.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=560&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Global emissions of ozone-depleting chemicals (CFCs, halons, HCFCs, and others) and their non-ozone depleting substitutes (HFCs) from 1950 to 2050, expressed as Gigatonnes of CO2-equivalent per year. The blue hatched regions indicate the emissions that would have occurred, in the absence of the Montreal Protocol, with 2–3% annual production increases in all ozone-depleting chemicals. Shown for reference are emissions for the range of CO2 scenarios from the IPCC Special Report on Emission Scenarios.</span>
<span class="attribution"><span class="source">WMO/UNEP Scientific Assessment of Ozone Depletion 2010</span></span>
</figcaption>
</figure>
<p>The Montreal Protocol was thus not only a very successful international policy agreement addressing ozone depletion, but has also reduced global warming, if only by a small amount.</p>
<p>This is another important reason to celebrate the 25th anniversary of the Montreal Protocol!</p>
<p><em><a href="https://theconversation.com/topics/saving-the-ozone">Read more</a> on the Montreal Protocol’s 25th anniversary.</em></p><img src="https://counter.theconversation.com/content/9404/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Karoly receives funding from the ARC, DCCEE, DIISR and the Australian Antarctic Division. He is a member of the ARC Centre of Excellence for Climate System Science, the Joint Scientific Committee of the World Climate Research Programme, the Climate Change Authority, the Science Advisory Panel of the Climate Commission, the National Committee for Earth System Science of the Australian Academy of Science, and the Wentworth Group of Concerned Scientists.</span></em></p>SAVING THE OZONE: Part five in our series exploring the Montreal Protocol on Substances that Deplete the Ozone Layer – dubbed “the world’s most successful environmental agreement” – explores the parallels…David Karoly, Professor of Atmospheric Science, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/92032012-09-12T20:35:46Z2012-09-12T20:35:46ZWhat are ozone depleting substances?<figure><img src="https://images.theconversation.com/files/15256/original/rq8mw33h-1347242776.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">By collecting air at pristine Cape Grim since 1978, scientists have been able to track the concentration of ozone depleting substances.</span> <span class="attribution"><span class="source">AAP/Bureau of Meteorology</span></span></figcaption></figure><p><em><a href="https://theconversation.com/topics/saving-the-ozone">SAVING THE OZONE</a>: Part four in our series exploring the Montreal Protocol on Substances that Deplete the Ozone Layer – dubbed “the world’s most successful environmental agreement” – looks at the substances that caused all this trouble in the first place.</em></p>
<p>In 1974, the world was alerted to the possible catastrophic depletion of stratospheric ozone by chlorofluorocarbons (CFCs), which were then emitted from domestic and commercial refrigeration and from air conditioning equipment, plastic foams and aerosol cans. Before 1974, CFCs were thought of as harmless chemical artifacts in the atmosphere, useful as tracers of the movement of air between countries and hemispheres.</p>
<p>In order to assess this threat to stratospheric ozone, which absorbs most of the harmful solar ultraviolet radiation impinging on the Earth’s atmosphere, scientists needed accurate information on the amounts and accumulation rates of CFCs in the global background atmosphere. Several nations, in particular Australia, the UK and the USA, responded quickly to this challenge. They established CFC-monitoring facilities in a number of strategic, clean-air locations around the world, in part funded by the global CFC industry.</p>
<p>CSIRO established the first Southern Hemispheric CFC measurement laboratory at Aspendale, Victoria, in 1975, and commenced in-situ measurements at Cape Grim, Tasmania, in early 1976. The Cape Grim station, funded and managed by the Australian Bureau of Meteorology, monitors and studies global atmospheric composition in a science program led by CSIRO and the Bureau.</p>
<p>By the early 1980s the atmospheric data, coupled with the industry estimates of global CFC production and emissions, proved that CFCs were long-lived, lasting more than 50 years in the atmosphere. This long life meant they could reach the stratosphere, where they broke down, releasing reactive chlorine species that catalytically destroyed ozone.</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/15234/original/g8mm73gq-1347237653.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/15234/original/g8mm73gq-1347237653.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=421&fit=crop&dpr=1 600w, https://images.theconversation.com/files/15234/original/g8mm73gq-1347237653.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=421&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/15234/original/g8mm73gq-1347237653.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=421&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/15234/original/g8mm73gq-1347237653.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=529&fit=crop&dpr=1 754w, https://images.theconversation.com/files/15234/original/g8mm73gq-1347237653.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=529&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/15234/original/g8mm73gq-1347237653.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=529&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Australian Baseline Station at Cape Grim – the first in-situ measurements of CFCs in the Southern Hemisphere started here in 1976 (in a caravan).</span>
<span class="attribution"><span class="source">Bureau of Meteorology</span></span>
</figcaption>
</figure>
<p>Scientists also realised that CFCs were not the only important ozone depleting substances (ODS) being released to the atmosphere. The chlorinated solvents carbon tetrachloride, and former dry-cleaning agents methyl chloroform, were identified as significant ODS. So were the halons – bromine containing fire-fighting chemicals – and methyl bromide, an agricultural and structural fumigant. The latter chemicals were identified as particularly potent ODS because they contained bromine, even more destructive of stratospheric ozone than chlorine.</p>
<p>To rapidly phase out CFCs, the industry developed the already existing HCFCs as interim replacement refrigerants and foaming agents. Hydrocarbons were developed as long-term replacements for CFCs in aerosol propellants. HCFCs were themselves ODSs, but because of their relatively short atmospheric lifetimes they were significantly less potent than the CFCs they replaced.</p>
<p>By 1987, just over a decade after the ozone threat was enunciated, the nations of the world came together to sign the Montreal Protocol, which controlled the production and consumptions of ODSs including HCFCs. Around the same time, the industry announced that it had developed safe, ozone-friendly CFC replacements, the hydrofluorocarbons (HFCs).</p>
<p>Unlike the CFCs and chlorinated solvents, accurate and comprehensive measurements of HCFCs, HFCs, the halons and methyl bromide were only possible by the mid-1990s. This was thanks to the development of a suitable measurement technology - gas chromatography-mass spectrometry (GC-MS) - and reliable calibration standards.</p>
<p>CSIRO and the Bureau of Meteorology had an archive of clean air samples collected regularly at Cape Grim since 1978 (the Cape Grim Air Archive). In the late 1990s, CSIRO got GC-MS capability and - in partnership with international laboratories at the University of California at San Diego, USA and the University of East Anglia at Norwich, UK - were able to reconstruct the complete ODS atmospheric history at Cape Grim back to 1978. CSIRO also applied these techniques to the analysis of air samples extracted in Antarctica, extending the complete ODS atmospheric history back to the 1930s.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/15233/original/26wrw63j-1347237653.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/15233/original/26wrw63j-1347237653.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=358&fit=crop&dpr=1 600w, https://images.theconversation.com/files/15233/original/26wrw63j-1347237653.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=358&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/15233/original/26wrw63j-1347237653.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=358&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/15233/original/26wrw63j-1347237653.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=450&fit=crop&dpr=1 754w, https://images.theconversation.com/files/15233/original/26wrw63j-1347237653.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=450&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/15233/original/26wrw63j-1347237653.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=450&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Figure 2: Effective chlorine levels (ppb) in the Southern Hemisphere atmosphere from in situ measurements at Cape Grim, on the Cape Grim Air Archive and on Antarctic firn air. The future scenario is from the WMO Scientific Assessment of Ozone Depletion: 2010.</span>
</figcaption>
</figure>
<p>The latest ODS data, as measured at Cape Grim, in the Cape Grim Air archive and in Antarctica are shown in Figure 2, expressed as the amount of chlorine potentially available for ozone destruction in the stratosphere.</p>
<p>The Cape Grim ODS data are available at the <a href="http://ds.data.jma.go.jp/gmd/wdcgg/">World Data Centre for Greenhouse Gases</a>. The Cape Grim Air Archive and Antarctic firn ODS data are available on request from the authors.</p>
<p>Chlorine levels rose rapidly from the 1960s, peaking in the late-1990s at about 4.4 parts per billion molar, before starting to decline, thanks to the successful implementation of the Montreal Protocol. Currently chlorine levels are falling by 6% per decade and it is anticipated they will fall to 1980s levels by about 2045 if the world continues to adhere to the Protocol. By then it is likely that the Antarctic ozone hole will be very weak or non-existent.</p>
<p><em>Tomorrow: the parallels between saving ozone and fighting climate change.</em></p>
<p><em><a href="https://theconversation.com/topics/saving-the-ozone">Read more</a> on the Montreal Protocol’s 25th anniversary.</em></p><img src="https://counter.theconversation.com/content/9203/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul Fraser receives funding from MIT, NASA, Bureau of Meteorology, DSEWPaC, DCCEE, Refrigerant Recliam Australia, </span></em></p><p class="fine-print"><em><span>Nada Derek receives funding from MIT, NASA, Bureau of Meteorology, DSEWPaC, DCCEE, Refrigerant Reclaim Australia.</span></em></p><p class="fine-print"><em><span>Paul Krummel receives funding from MIT, NASA, Bureau of Meteorology, DSEWPaC, DCCEE, & Refrigerant Reclaim Australia.</span></em></p><p class="fine-print"><em><span>Paul Steele does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>SAVING THE OZONE: Part four in our series exploring the Montreal Protocol on Substances that Deplete the Ozone Layer – dubbed “the world’s most successful environmental agreement” – looks at the substances…Paul Fraser, Stream Leader, Changing Atmosphere, CSIRONada Derek, Centre for Australian Weather and Climate Research , CSIROPaul Krummel, Centre for Australian Weather and Climate Research , CSIROPaul Steele, Centre for Australian Weather and Climate Research , CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/92062012-09-11T20:23:24Z2012-09-11T20:23:24ZHow does the ozone layer protect Earth from radiation?<figure><img src="https://images.theconversation.com/files/15068/original/9gm33jf4-1346820221.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">This is bad, but it would be a lot worse without the ozone layer.</span> <span class="attribution"><span class="source">garth.kennedy/Flickr</span></span></figcaption></figure><p><em><a href="https://theconversation.com/topics/saving-the-ozone">SAVING THE OZONE</a>: Part three in our series exploring on the Montreal Protocol on Substances that Deplete the Ozone Layer – dubbed “the world’s most successful environmental agreement” – explains why we need an ozone layer.</em></p>
<p>The ozone layer acts as a filter for the shorter wavelength and highly hazardous ultraviolet radiation (UVR) from the sun, protecting life on Earth from its potentially harmful effects. When the sky is clear, there is an inverse relationship between stratospheric ozone and solar UVR measured at the Earth’s surface. That is,the lower the ozone levels, the higher the solar UVR.</p>
<p>The level of UVR from the sun measured at the Earth’s surface varies linearly with latitude. There are higher UVR levels nearer the equator and lower UVR nearer the poles (see Figure 1). </p>
<p>Australia has high levels of solar UVR, due mainly to its geographical position. We have capital cities at latitudes ranging from 12°30’S (Darwin) close to the equator down to 42°52’S (Hobart). For comparison with some Northern Hemisphere locations, the south of France is 43°N and London is 51°32’N, while Melbourne at 37°46’S is as far from the equator as the coast of North Africa (37°16’N). </p>
<p>The southern hemisphere generally has higher levels of solar UVR than the northern hemisphere, because the Earth is approximately 1.7% closer to the sun in January (summer) than at the equinox and 1.7% further away in July (northern hemisphere summer). The intensity of solar UVR is proportional to the square of the distance, so this means solar UVR levels are already 3.4% higher in the southern Hemisphere than at equinox and 3.4% lower for an equivalent location in the northern hemisphere. However as the atmosphere in the southern hemisphere is cleaner than that in the northern and transmits UVR more readily, these differences are even larger for similar latitudes, approaching ~15%. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/15067/original/2pdcqnw5-1346819312.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/15067/original/2pdcqnw5-1346819312.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=393&fit=crop&dpr=1 600w, https://images.theconversation.com/files/15067/original/2pdcqnw5-1346819312.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=393&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/15067/original/2pdcqnw5-1346819312.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=393&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/15067/original/2pdcqnw5-1346819312.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=493&fit=crop&dpr=1 754w, https://images.theconversation.com/files/15067/original/2pdcqnw5-1346819312.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=493&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/15067/original/2pdcqnw5-1346819312.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=493&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Figure 1. Measured solar UVR data versus latitude for a number of locations in different countries. The Southern Hemisphere sites are Australia and New Zealand as well as the Australian Antarctic Stations (at just below 70°S) and are marked as AAD and with UVR levels well above the other high latitude locations due to the effects of the ozone hole. Macquarie Island (at ~ 55°S) has annual UVR levels that are unaffected by the ozone hole. The Northern Hemisphere sites are the US (which has the highest data shown in this graph at Mauna Loa in Hawaii at 20°N and 3800m altitude), Japan and a number of European counties.</span>
</figcaption>
</figure>
<p>Australians are predominantly descended from fair-skinned individuals used to European conditions, so exposure to these high levels of solar UVR has resulted in very high rates of skin cancer within the population. Deaths are now more than 1800 per year with a cost to the health system of more than $300M annually.</p>
<p>Generally the higher the sun is in the sky, the shorter the path through the atmosphere and the higher the solar UVR levels. The maximum height of the sun in the sky changes slowly from day to day, but ozone over a location can change considerably from one day to the next due to natural variability. Levels can rise or fall by up to 100 Dobson Units (DU) in 24 hours. </p>
<p>For consecutive clear sky days, large but natural changes in ozone levels in the stratosphere above cities can affect the solar UVR at the surface significantly. There are differences of up to 30 to 40% from one day to the next, with measured daily UV index values increasing or decreasing inversely with large daily decreases or increases in ozone.</p>
<p>The ozone hole - discovered in the early 1980s - and its effects on solar UVR levels over the Antarctic and possibly further north could only add to the problem of population UVR exposures. The southern hemisphere has been affected more by ozone depletion than the northern hemisphere due to several geophysical and atmospheric factors which have lead to the annual appearance of the ozone hole over Antarctica. </p>
<p>Measurements of the solar UVR levels at the Australian Stations in the Antarctic (Casey, Davis and Mawson) show as the ozone hole passes overhead each spring, the annual levels of solar UVR at the stations have increased significantly. They are now equivalent to that received at numerous places in Europe. Interestingly, Macquarie Island, which is outside the reach of the Antarctic ozone hole, shows little in the way of increased annual solar UVR levels. </p>
<p>Because the annual ozone hole breaks up in spring, pockets of ozone-depleted air sometimes move northwards and pass over Australia adding slightly to the solar UVR levels there (this was first observed in the late 1980s). Recently there have been incidents of low ozone over Australia due to other atmospheric processes dragging low-ozone upper-atmospheric air down from equatorial regions (ozone is generally lower over the equator than at mid-latitudes). In such cases UV index levels at the ground are elevated and increase the potential for adverse health effects for populations living in these areas.</p>
<p>If not for the success of the Montreal Protocol it is very likely that the more densely populated areas of the globe would be subject to increased solar UVR with potentially severe consequences for (human) health.</p>
<p><em>This article was co-authored by Stuart Henderson, who works with Peter Gies in the UVR Group in the Radiation Health Services Branch at the Australian Radiation Protection and Nuclear Safety Agency. Stuart Henderson has a PhD in Applied Physics from RMIT.</em></p>
<p><em>Tomorrow: what are ozone depleting substances?</em></p>
<p><em><a href="https://theconversation.com/topics/saving-the-ozone">Read more</a> on the Montreal Protocol’s 25th anniversary.</em></p><img src="https://counter.theconversation.com/content/9206/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter Gies does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>SAVING THE OZONE: Part three in our series exploring on the Montreal Protocol on Substances that Deplete the Ozone Layer – dubbed “the world’s most successful environmental agreement” – explains why we…Peter Gies, Senior Principal Research Fellow (Honorary), James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/92022012-09-10T20:25:48Z2012-09-10T20:25:48ZExplainer: what is the Antarctic ozone hole and how is it made?<figure><img src="https://images.theconversation.com/files/15123/original/7k4fs33k-1346905588.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">For more than three decades Antarctica has experienced the most severe depletion of stratospheric ozone.</span> <span class="attribution"><span class="source">NASA Goddard Photo and Video</span></span></figcaption></figure><p><em><a href="https://theconversation.com/topics/saving-the-ozone">SAVING THE OZONE</a>: Part two in our series exploring on the Montreal Protocol on Substances that Deplete the Ozone Layer – dubbed “the world’s most successful environmental agreement”. <a href="https://theconversation.com/saving-the-ozone-layer-why-the-montreal-protocol-worked-9249">Yesterday’s article</a> looked at why the protocol was a success. Today, what is the ozone hole?</em></p>
<p>Ozone is fundamentally important for life on Earth. It forms a natural layer in the stratosphere which acts as a sunscreen to filter out harmful ultraviolet radiation.</p>
<p>Human activities have had a dramatic impact on the health of the ozone layer, and we are still witnessing these effects most significantly at high latitudes. For more than three decades Antarctica has experienced the most severe depletion of stratospheric ozone in what is commonly referred to as the Antarctic “ozone hole”.</p>
<p>So how does the ozone hole form and what is the current outlook for ozone?</p>
<h2>Chemical ingredients</h2>
<p>The most potent man-made ozone depleting substances (ODS) are those that are halogenated – that is, they contain chlorine and bromine.</p>
<p>Halogenated ODS are effectively inert in the lower atmosphere. The overturning motions associated with warming and cooling of airmasses in the lower atmosphere allows some of the ODS to be transported into the stratosphere. The substances are then broken down by ultraviolet light and form stable halogenated “reservoir” compounds, which by themselves do not strongly affect ozone. </p>
<p>The main problem arises when the reservoir compounds are further altered to create halogenated “reactive” radicals. This is done through processes that largely take place on the surfaces of tiny stratospheric aerosol particles. These reactions make the by-products of the ODS more potent for ozone destruction.</p>
<p>The amount of particles taking part in this process is significantly enhanced in Antarctica over winter. This is because of the presence of Polar Stratospheric Clouds (PSCs) in the lower stratosphere.</p>
<h2>Special Antarctic conditions</h2>
<p>PSCs are made up of tiny particles made up primarily of nitric acid and water vapour, and require a temperature of around -80°C or colder to form. In winter, a vortex of air forms in the stratosphere over Antarctica. Within the vortex, air circulates with minimal mixing with the rest of the atmosphere. This drives strong cooling of the lower stratosphere and creates the conditions favourable for PSC formation. </p>
<p>When spring comes, the halogens released by the PSCs are broken down by sunlight. The resulting free chlorine and bromine atoms destroy ozone before being cycled back into halogen radicals. The presence of sunlight begins the cycle again. </p>
<p>Overall, the reaction cycle destroys many ozone molecules for each chlorine and bromine atom present. PSC formation enhances the cycle as it removes certain nitrogen compounds from the atmosphere. These compounds would otherwise reduce the overall amount of halogenated radicals present.</p>
<h2>Life cycle of the hole</h2>
<p>Ozone destruction peaks in early spring and ends by late spring or early summer. The warming atmosphere evaporates the PSCs thereby inhibiting the cycle. It breaks down the vortex, resulting in the dispersal of ozone-poor air to mid-latitudes and allowing ozone-rich air from outside the vortex to flow over Antarctica.</p>
<p>Ozone destruction is related to the amount of chlorine and bromine present in the polar stratosphere. This is influenced by the amount of chemical processing by PSCs, along with the size, stability and temperature of the vortex.</p>
<h2>The Arctic and the rest of the globe</h2>
<p>Ozone destruction also occurs in the Arctic, although with less severity and consistency than Antarctica. The Arctic winter stratosphere is less cold and stable than that of Antarctica, producing lesser amounts of the destructive halogenated radicals.</p>
<p>Ozone depletion reactions triggered by the breakdown of ODS in the stratosphere take place around the globe, although with far less effectiveness than in the Antarctic.</p>
<h2>The Antarctic ozone hole: looking back and forward</h2>
<p>The Antarctic ozone hole was first clearly apparent around 1980, although signs of ozone decline at specific Antarctic sites have been traced back to the 1970s and possibly earlier.</p>
<p>The various metrics that assess the size and severity of the ozone hole show that the Antarctic hole grew through the 1980s and generally levelled-off in size during mid-1990s. Dominant factors have been the size and strength of the polar vortex and temperature of the lower stratosphere in the time since. </p>
<p>Year-to-year size variations in the ozone hole are driven largely by meteorological variability rather than changes in ODS. Years where the polar vortex was large, stable and cold, such as 2000 and 2006, are associated with the most extensive ozone loss. An unusual year was 2002, when the polar vortex broke down in an unprecedented and dramatic way after a winter of relatively mild stratospheric temperatures and disturbed circulation. In that year, the severity of ozone loss was lower, similar to the mid-1980s.</p>
<p>In recent years there is increasing evidence that the declining level of ODS are playing a mitigating role in the overall size of ozone hole.</p>
<p>Clearer evidence of a reversal in the severity of Antarctic ozone hole should emerge over the next decade. The trend produced by the decline in ODS will become more apparent against year-by-year variability from meteorological processes. The current expectation is that pre-1980 levels of ozone in the Antarctic region will return around the middle of this century.</p>
<p><em>Tomorrow: how does the ozone layer protect Earth from radiation?</em></p>
<p><em><a href="https://theconversation.com/topics/saving-the-ozone">Read more</a> on the Montreal Protocol’s 25th anniversary.</em></p><img src="https://counter.theconversation.com/content/9202/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Klekociuk does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>SAVING THE OZONE: Part two in our series exploring on the Montreal Protocol on Substances that Deplete the Ozone Layer – dubbed “the world’s most successful environmental agreement”. Yesterday’s article…Andrew Klekociuk, Honorary Research Associate, University of TasmaniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/92492012-09-09T20:23:12Z2012-09-09T20:23:12ZSaving the ozone layer: why the Montreal Protocol worked<figure><img src="https://images.theconversation.com/files/15057/original/3xcmq29b-1346809350.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Montreal Protocol negotiators should get a lot of credit for developing such a flexible treaty.</span> <span class="attribution"><span class="source">hhesterr/Flickr</span></span></figcaption></figure><p><em><a href="https://theconversation.com/topics/saving-the-ozone">SAVING THE OZONE</a>: It might not seem so long ago that the discovery of the hole in the ozone layer over Antarctica had us in a frenzy over CFCs in hairsprays and insecticides. In fact, on September 16 2012, it will be 25 years since the Montreal Protocol on Substances that Deplete the Ozone Layer was signed. To mark this occasion, The Conversation is running a series of articles exploring various aspects of the Montreal Protocol – dubbed “the world’s most successful environmental agreement”. The work is not over, but 25 years of success is something to celebrate.</em></p>
<p>The Montreal Protocol is one of the most successful and effective environmental treaties ever negotiated and implemented. No single factor led to its success. But if an overarching reason is needed, look no further than the unprecedented level of cooperation and commitment shown by the international community.</p>
<p>The <a href="http://ozone.unep.org/new_site/en/montreal_protocol.php">Montreal Protocol</a> on Substances that Deplete the Ozone Layer aimed to ban the global production and use of ozone-damaging chemicals including <a href="http://en.wikipedia.org/wiki/Chlorofluorocarbon">CFCs</a>, <a href="http://www.environment.gov.au/atmosphere/ozone/licences/hcfcapplication.html">HCFCs</a> and <a href="http://www.environment.gov.au/atmosphere/ozone/ods/halon/index.html">halon</a>. From the start, negotiation relied heavily on leadership and innovative approaches. Much negotiation was held in small, informal groups. This enabled a genuine exchange of views and the opportunity to take some issues on trust, such as the subsequent development of the <a href="http://www.multilateralfund.org/aboutMLF/default.aspx">Multilateral Fund</a>. The people negotiating the treaty also included scientists, which lent credibility.</p>
<p>The science was not definite at the time, so it was a credit to the negotiators that they developed a highly flexible instrument which could increase or decrease controls as the science became clearer. It was only after the initial framework was negotiated that the science became firmer: early conclusions about the extent of ozone depletion turned out to be significantly under-estimated.</p>
<p>This flexibility meant the protocol could be amended to include stricter controls: more ozone-depleting substances added to the control list and total phase-out, rather than partial phase-out, called for. Starting out modestly also encouraged a greater confidence in the process.</p>
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<img alt="" src="https://images.theconversation.com/files/15154/original/3gwg8v3q-1346977959.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/15154/original/3gwg8v3q-1346977959.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=660&fit=crop&dpr=1 600w, https://images.theconversation.com/files/15154/original/3gwg8v3q-1346977959.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=660&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/15154/original/3gwg8v3q-1346977959.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=660&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/15154/original/3gwg8v3q-1346977959.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=829&fit=crop&dpr=1 754w, https://images.theconversation.com/files/15154/original/3gwg8v3q-1346977959.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=829&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/15154/original/3gwg8v3q-1346977959.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=829&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p>One element that encouraged countries to ratify the Montreal Protocol was the trade provisions. These limited signatories to trade only with other signatories. Once the main producing countries signed up, it was only a matter of time before all countries had to sign up or risk not having access to increasingly limited supplies of CFCs and other ozone-depleting substances (ODS).</p>
<p>During the protocol’s negotiation, principles now routinely applied to the development of international agreements were first given a voice. Chief among these was the idea of taking action when the science was not yet conclusive. This forms the basis of the “precautionary principle”, later enshrined in Principle 15 of the <a href="http://www.unep.org/Documents.Multilingual/Default.asp?documentid=78&articleid=1163">1992 Rio Declaration</a>. And the concept of common, but differentiated, responsibility took root in the Montreal Protocol when developing countries were given longer to phase-out ODS.</p>
<p>The implementation of the Montreal Protocol has been highly successful for a number of reasons. The chemicals and sectors (refrigeration, primarily) involved are clearly articulated. This let governments prioritise the main sectors early. </p>
<p>The Montreal Protocol also provided a stable framework that allowed industry to plan long-term research and innovation. It was a happy coincidence that there were benefits for industry of moving away from ODS. CFCs were old technology and well out of patent. Transitioning to newer, reasonably priced formulations with lower- or no-ozone depleting potential benefited the environment and industry. </p>
<p>To their credit, chemicals companies have kept innovating. They are now producing chemicals with no ozone depleting potential and with lower global warming potential as well, for use in the refrigeration and air conditioning sectors.</p>
<p>Another feature of the protocol has been the expert, independent <a href="http://ozone.unep.org/Assessment_Panels/TEAP/index.shtml">Technology and Economic Assessment Panel</a> (and its predecessors). These have helped signatories reach solid and timely decisions on often-complex matters. They have given countries confidence to start their transition.</p>
<p>The Multilateral Fund has been another reason for the protocol’s success. It provides incremental funding for developing countries to help them meet their compliance targets. Significantly, it has also provided institutional support. This helps countries build capacity within their governments to implement phase-out activities and establish regional networks so they can share experiences and learn from each other.</p>
<p>A final reason for the protocol’s successful implementation has been its compliance procedure. This was designed from the outset as a non-punitive procedure. It prioritised helping wayward countries back into compliance. Developing countries work with a UN agency to prepare an action plan to get themselves back into compliance. If necessary, resources from the Multilateral Fund are available for some short-term projects. It is telling that all 142 developing countries were able to meet the 100% phase-out mark for CFCs, halons and other ODS in 2010.</p>
<p>Australian government and industry’s shared commitment to protecting the ozone layer has been pivotal in our success at meeting our protocol obligations. Australia, and the ozone layer, have also benefited from the dedication and expertise of many individuals from our scientific and technical organisations, industry and from government.</p>
<p>The Montreal Protocol is a remarkable instrument. It broke new ground in its negotiation and in its construction. It is ratified or accepted by all 197 UN member states, a world first for any treaty and highlighting the strong global commitment to this treaty. </p>
<p>Most importantly it is doing its job well. The ozone layer is expected to return to 1980 levels between 2045 and 2060 as long as all countries continue to meet their obligations and phase out the last ozone-depleting substances in the next few years.</p>
<p>Phasing out ozone-depleting substances has also benefited the environment more broadly, as many ozone-depleting substances also have high global warming potential. It is a credit to governments, industry, environment groups, science and technical experts that such an instrument is even in existence and doing such a great job.</p>
<p><em>Tomorrow, in part two of the series, we’ll look at why the Antarctic ozone hole formed.</em></p>
<p><em>This article was co-authored by Annie Gabriel, who works for the Department of Sustainability, Environment, Water, Population and Communities on ozone protection policy. She has a BA from the ANU and a Graduate Certificate in Public Policy from Flinders University.</em></p>
<p><em><a href="https://theconversation.com/topics/saving-the-ozone">Read more</a> on the Montreal Protocol’s 25th anniversary.</em></p><img src="https://counter.theconversation.com/content/9249/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ian Rae does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>SAVING THE OZONE: It might not seem so long ago that the discovery of the hole in the ozone layer over Antarctica had us in a frenzy over CFCs in hairsprays and insecticides. In fact, on September 16 2012…Ian Rae, Honorary Professorial Fellow, Faculty of Arts, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.