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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Ozone layer</span></span>
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<p>The <b>ozone layer</b> or <b>ozone shield</b> is a region of <a href="Earth" title="Earth">Earth</a>'s <a href="Stratosphere" title="Stratosphere">stratosphere</a> that <a href="Absorption_(electromagnetic_radiation)" title="Absorption (electromagnetic radiation)">absorbs</a> most of the <a href="Sun" title="Sun">Sun</a>'s <a href="Ultraviolet" title="Ultraviolet">ultraviolet</a> radiation. It contains a high concentration of <a href="Ozone" title="Ozone">ozone</a> (O<sub>3</sub>) in relation to other parts of the atmosphere, although still small in relation to other gases in the stratosphere. The ozone layer peaks at 8 to 15 <a href="Parts_per_million" class="mw-redirect" title="Parts per million">parts per million</a> of ozone,<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> while the average ozone concentration in Earth's atmosphere as a whole is about 0.3 parts per million. The ozone layer is mainly found in the lower portion of the stratosphere, from approximately 15 to 35 kilometers (9 to 22&nbsp;mi) above Earth, although its thickness varies seasonally and geographically.<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>
</p><p>The ozone layer was discovered in 1913 by French physicists <a href="Charles_Fabry" title="Charles Fabry">Charles Fabry</a> and <a href="Henri_Buisson" title="Henri Buisson">Henri Buisson</a>. Measurements of the sun showed that the radiation sent out from its surface and reaching the ground on Earth is usually consistent with the <a href="Spectrum" title="Spectrum">spectrum</a> of a <a href="Black_body" title="Black body">black body</a> with a temperature in the range of 5,500–6,000&nbsp;K (5,230–5,730&nbsp;°C), except that there was no radiation below a <a href="Wavelength" title="Wavelength">wavelength</a> of about 310&nbsp;nm at the <a href="Ultraviolet" title="Ultraviolet">ultraviolet</a> end of the spectrum. It was deduced that the missing radiation was being absorbed by something in the atmosphere. Eventually the spectrum of the missing radiation was matched to only one known chemical, ozone.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> Its properties were explored in detail by the British <a href="Meteorologist" title="Meteorologist">meteorologist</a> <a href="G._M._B._Dobson" title="G. M. B. Dobson">G. M. B. Dobson</a>, who developed a simple <a href="Spectrophotometry" title="Spectrophotometry">spectrophotometer</a> (the <a href="Dobson_spectrometer" class="mw-redirect" title="Dobson spectrometer">Dobsonmeter</a>) that could be used to measure stratospheric ozone from the ground. Between 1928 and 1958, Dobson established a worldwide network of ozone monitoring stations, which continue to operate to this day. The "<a href="Dobson_unit" title="Dobson unit">Dobson unit</a>" (DU), a convenient measure of the <a href="Area_density" title="Area density">amount</a> of ozone overhead, is named in his honor.
</p><p>The ozone layer absorbs 97 to 99 percent of the Sun's medium-frequency ultraviolet light (from about 200&nbsp;<a href="Nanometer" class="mw-redirect" title="Nanometer">nm</a> to 315&nbsp;nm wavelength), which otherwise would potentially damage exposed life forms near the surface.<sup id="cite_ref-NASA_4-0" class="reference"><a href="#cite_note-NASA-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup>
</p><p>In 1985, atmospheric research revealed that the ozone layer was being depleted by chemicals released by industry, mainly <a href="Chlorofluorocarbon" title="Chlorofluorocarbon">chlorofluorocarbons</a> (CFCs). Concerns that increased UV radiation due to <a href="Ozone_depletion" title="Ozone depletion">ozone depletion</a> threatened life on Earth, including increased skin cancer in humans and other ecological problems,<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> led to bans on the chemicals, and the latest evidence is that ozone depletion has slowed or stopped. The United Nations General Assembly has designated September 16 as the <a href="International_Day_for_the_Preservation_of_the_Ozone_Layer" title="International Day for the Preservation of the Ozone Layer">International Day for the Preservation of the Ozone Layer</a>.
</p><p><a href="Venus" title="Venus">Venus</a> also has a thin ozone layer at an altitude of 100 kilometers above the planet's surface.<sup id="cite_ref-venus_ozone_6-0" class="reference"><a href="#cite_note-venus_ozone-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup>
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<div class="mw-heading mw-heading2"><h2 id="Sources">Sources</h2></div>
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</style><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Ozone%E2%80%93oxygen_cycle" title="Ozone–oxygen cycle">Ozone–oxygen cycle</a></div>

<p>The Earth's ozone layer formed about 500 million years ago, when the <a href="Neoproterozoic_oxygenation_event" title="Neoproterozoic oxygenation event">neoproterozoic oxygenation event</a> brought the fraction of oxygen in the atmosphere to about 20%.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup>
</p><p>The <a href="Photochemical" class="mw-redirect" title="Photochemical">photochemical</a> mechanisms that give rise to the ozone layer were discovered by the British physicist <a href="Sydney_Chapman_(mathematician)" title="Sydney Chapman (mathematician)">Sydney Chapman</a> in 1930. Ozone in the Earth's stratosphere is created by ultraviolet light striking ordinary <a href="Oxygen" title="Oxygen">oxygen</a> <a href="Molecule" title="Molecule">molecules</a> containing two oxygen <a href="Atom" title="Atom">atoms</a> (O<sub>2</sub>), splitting them into individual oxygen atoms (<a href="Atomic_oxygen" class="mw-redirect" title="Atomic oxygen">atomic oxygen</a>); the atomic oxygen then combines with unbroken O<sub>2</sub> to create ozone, O<sub>3</sub>. The ozone molecule is unstable (although, in the stratosphere, long-lived) and when ultraviolet light hits ozone it splits into a molecule of O<sub>2</sub> and an individual atom of oxygen, a continuing process called the <a href="Ozone%E2%80%93oxygen_cycle" title="Ozone–oxygen cycle">ozone–oxygen cycle</a>. Chemically, this can be described as:
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<dl><dd><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\ce {O2{}+{\mathit {h}}\nu _{uv}->2O}}}">
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<dd><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\ce {O + O2 <-> O3}}}">
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<p>About 90% of the ozone in the atmosphere is contained in the stratosphere. Ozone concentrations are greatest between about 20 and 40 kilometres (66,000 and 131,000&nbsp;ft), where they range from about 2 to 8 parts per million. If all of the ozone were compressed to the pressure of the air at sea level, it would be only <style data-mw-deduplicate="TemplateStyles:r1154941027">
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</style>3 millimetres (<span class="frac"><span class="num">1</span>⁄<span class="den">8</span></span> inch) thick.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup>
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<div class="mw-heading mw-heading2"><h2 id="Ultraviolet_light">Ultraviolet light</h2></div>


<p>Although the concentration of the ozone in the ozone layer is very small, it is vitally important to life because it absorbs biologically harmful ultraviolet (UV) radiation coming from the Sun. Extremely short or vacuum UV (10–100&nbsp;nm) is screened out by nitrogen. UV radiation capable of penetrating nitrogen is divided into three categories, based on its wavelength; these are referred to as UV-A (400–315&nbsp;nm), <a href="UV-B" class="mw-redirect" title="UV-B">UV-B</a> (315–280&nbsp;nm), and <a href="UV-C" class="mw-redirect" title="UV-C">UV-C</a> (280–100&nbsp;nm).
</p><p>UV-C, which is very harmful to all living things, is entirely screened out by a combination of dioxygen (&lt; 200&nbsp;nm) and ozone (&gt; about 200&nbsp;nm) by around 35 kilometres (115,000&nbsp;ft) altitude. UV-B radiation can be harmful to the skin and is the main cause of <a href="Sunburn" title="Sunburn">sunburn</a>; excessive exposure can also cause cataracts, immune system suppression, and genetic damage, resulting in problems such as <a href="Skin_cancer" title="Skin cancer">skin cancer</a>. The ozone layer (which absorbs from about 200&nbsp;nm to 310&nbsp;nm with a maximal absorption at about 250&nbsp;nm)<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> is very effective at screening out UV-B; for radiation with a wavelength of 290&nbsp;nm, the intensity at the top of the atmosphere is 350 million times stronger than at the Earth's surface. Nevertheless, some UV-B, particularly at its longest wavelengths, reaches the surface, and is important for the skin's production of <a href="Vitamin_D" title="Vitamin D">vitamin D</a> in <a href="Mammals" class="mw-redirect" title="Mammals">mammals</a>.
</p><p>Ozone is transparent to most UV-A, so most of this longer-wavelength UV radiation reaches the surface, and it constitutes most of the UV reaching the Earth. This type of UV radiation is significantly less harmful to <a href="DNA" title="DNA">DNA</a>, although it may still potentially cause physical damage, premature aging of the skin, indirect genetic damage, and skin cancer.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup>
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<div class="mw-heading mw-heading2"><h2 id="Distribution_in_the_stratosphere">Distribution in the stratosphere</h2></div>
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<p>The thickness of the ozone layer varies worldwide and is generally thinner near the equator and thicker near the poles.<sup id="cite_ref-APH_11-0" class="reference"><a href="#cite_note-APH-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> Thickness refers to how much ozone is in a column over a given area and varies from season to season. The reasons for these variations are due to atmospheric circulation patterns and solar intensity.<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup>
</p><p>The ozone layer ends gradually, but in general its upper limit is where air becomes too thin for UV light to generate much ozone, and its lower limit is where generated ozone blocks enough UV light to stop most ozone production.
</p><p>In the <a href="Homosphere" title="Homosphere">homosphere</a>, wind-driven movement is more important than relative gas weight. The majority of ozone is produced over the <a href="Tropics" title="Tropics">tropics</a> and is transported toward the poles by stratospheric wind patterns. In the northern hemisphere these patterns, known as the <a href="Brewer%E2%80%93Dobson_circulation" title="Brewer–Dobson circulation">Brewer–Dobson circulation</a>, make the ozone layer thickest in the spring and thinnest in the fall.<sup id="cite_ref-APH_11-1" class="reference"><a href="#cite_note-APH-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> When ozone is produced by solar UV radiation in the tropics, it is done so by circulation lifting ozone-poor air out of the troposphere and into the stratosphere where the sun <a href="Photolyzes" class="mw-redirect" title="Photolyzes">photolyzes</a> oxygen molecules and turns them into ozone. Then, the ozone-rich air is carried to higher latitudes and drops into lower layers of the atmosphere.<sup id="cite_ref-APH_11-2" class="reference"><a href="#cite_note-APH-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup>
</p><p>Research has found that the ozone levels in the United States are highest in the spring months of April and May and lowest in October. While the total amount of ozone increases moving from the tropics to higher latitudes, the concentrations are greater in high northern latitudes than in high southern latitudes, with spring ozone columns in high northern latitudes occasionally exceeding 600 DU and averaging 450 DU whereas 400 DU constituted a usual maximum in the Antarctic before anthropogenic ozone depletion. This difference occurred naturally because of the weaker polar vortex and stronger Brewer–Dobson circulation in the northern hemisphere owing to that hemisphere's large mountain ranges and greater contrasts between land and ocean temperatures.<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> The difference between high northern and southern latitudes has increased since the 1970s due to the <a href="Ozone_hole" class="mw-redirect" title="Ozone hole">ozone hole</a> phenomenon.<sup id="cite_ref-APH_11-3" class="reference"><a href="#cite_note-APH-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> The highest amounts of ozone are found over the Arctic during the spring months of March and April, but the Antarctic has the lowest amounts of ozone during the summer months of September and October,
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<div class="mw-heading mw-heading2"><h2 id="Depletion">Depletion</h2></div>
<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Ozone_depletion" title="Ozone depletion">Ozone depletion</a></div>

<p>The ozone layer can be depleted by <a href="Free_radical" class="mw-redirect" title="Free radical">free radical</a> <a href="Catalysis" title="Catalysis">catalysts</a>, including <a href="Nitric_oxide" title="Nitric oxide">nitric oxide</a> (NO), <a href="Nitrous_oxide" title="Nitrous oxide">nitrous oxide</a> (N<sub>2</sub>O), <a href="Hydroxyl" class="mw-redirect" title="Hydroxyl">hydroxyl</a> (OH), atomic <a href="Chlorine" title="Chlorine">chlorine</a> (Cl), and atomic <a href="Bromine" title="Bromine">bromine</a> (Br). While there are natural sources for all of these <a href="Chemical_species" title="Chemical species">species</a>, the concentrations of chlorine and bromine increased markedly in recent decades because of the release of large quantities of man-made <a href="Organohalogen" class="mw-redirect" title="Organohalogen">organohalogen</a> compounds, especially <a href="Chlorofluorocarbon" title="Chlorofluorocarbon">chlorofluorocarbons</a> (CFCs) and <a href="Bromofluorocarbons" class="mw-redirect" title="Bromofluorocarbons">bromofluorocarbons</a>.<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> Atmospheric components are not sorted out by weight in the <a href="Homosphere" title="Homosphere">homosphere</a> because of wind-driven mixing that extends to an altitude of about 90 km, well above the ozone layer. So despite being heavier than diatomic nitrogen and oxygen, these highly stable compounds rise into the <a href="Stratosphere" title="Stratosphere">stratosphere</a>, where Cl and Br <a href="Radical_(chemistry)" title="Radical (chemistry)">radicals</a> are liberated by the action of ultraviolet light. Each radical is then free to initiate and catalyze a chain reaction capable of breaking down over 100,000 ozone molecules. By 2009, nitrous oxide was the largest ozone-depleting substance (ODS) emitted through human activities.<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup>
</p><p>The breakdown of ozone in the stratosphere results in reduced absorption of ultraviolet radiation. Consequently, unabsorbed and dangerous ultraviolet radiation reaches the Earth's surface at a higher intensity. Ozone levels have dropped by a worldwide average of about 4 percent since the late 1970s. For approximately 5 percent of the Earth's surface, around the north and south poles, much larger seasonal declines have been seen, and are described as "ozone holes". "Ozone holes" are actually patches in the ozone layer in which the ozone is thinner. The thinnest parts of the ozone are at the <a href="Polar_regions_of_Earth" title="Polar regions of Earth">polar points of Earth's axis</a>.<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> The discovery of the annual depletion of ozone above the Antarctic was first announced by <a href="Joe_Farman" title="Joe Farman">Joe Farman</a>, <a href="Brian_G._Gardiner_(meteorologist)" title="Brian G. Gardiner (meteorologist)">Brian Gardiner</a>, and <a href="Jonathan_Shanklin" class="mw-redirect" title="Jonathan Shanklin">Jonathan Shanklin</a>, in a paper which appeared in <i><a href="Nature_(journal)" title="Nature (journal)">Nature</a></i> on May 16, 1985.
</p><p>Regulation attempts have included but not have been limited to the <a href="Clean_Air_Act_(United_States)" title="Clean Air Act (United States)">Clean Air Act</a> implemented by the <a href="United_States_Environmental_Protection_Agency" title="United States Environmental Protection Agency">United States Environmental Protection Agency</a>. The Clean Air Act introduced the requirement of <a rel="nofollow" class="external text" href="https://www.epa.gov/criteria-air-pollutants/naaqs-table">National Ambient Air Quality Standards (NAAQS)</a> with ozone pollutions being one of six criteria pollutants. This regulation has proven to be effective since counties, cities, and tribal regions must abide by these standards and the EPA also provides assistance for each region to regulate contaminants.<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> Effective presentation of information has also proven to be important in order to educate the general population of the existence and regulation of ozone depletion and contaminants. A scientific paper was written by Sheldon Ungar in which the author explores and studies how information about the depletion of the ozone, <a href="Climate_change" title="Climate change">climate change</a>, and various related topics. The ozone case was communicated to lay persons "with easy-to-understand bridging metaphors derived from the popular culture" and related to "immediate risks with everyday relevance".<sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> The specific metaphors used in the discussion (ozone shield, ozone hole) proved quite useful and, compared to global climate change, the ozone case was much more seen as a "hot issue" and imminent risk. Lay people were cautious about a depletion of the ozone layer and the risks of skin cancer.
</p><p><a href="Satellite" title="Satellite">Satellites</a> burning up upon re-entry into Earth's atmosphere produce <a href="Aluminum_oxide" class="mw-redirect" title="Aluminum oxide">aluminum oxide</a> (Al<sub>2</sub>O<sub>3</sub>) <a href="Nanoparticle" title="Nanoparticle">nanoparticles</a> that endure in the atmosphere for decades.<sup id="cite_ref-GeophysResearchLtrs_20240611_19-0" class="reference"><a href="#cite_note-GeophysResearchLtrs_20240611-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> Estimates for 2022 alone were ~17 metric tons (~30<span class="nowrap">&nbsp;</span>kg of nanoparticles per ~250<span class="nowrap">&nbsp;</span>kg satellite).<sup id="cite_ref-GeophysResearchLtrs_20240611_19-1" class="reference"><a href="#cite_note-GeophysResearchLtrs_20240611-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> Increasing populations of <a href="Satellite_constellation" title="Satellite constellation">satellite constellations</a> can eventually lead to significant ozone depletion.<sup id="cite_ref-GeophysResearchLtrs_20240611_19-2" class="reference"><a href="#cite_note-GeophysResearchLtrs_20240611-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup>
</p><p>"Bad" ozone can cause adverse health risks respiratory effects (difficulty breathing) and is proven to be an aggravator of respiratory illnesses such as <a href="Asthma" title="Asthma">asthma</a>, <a href="Chronic_obstructive_pulmonary_disease" title="Chronic obstructive pulmonary disease">COPD</a>, and <a href="Emphysema" title="Emphysema">emphysema</a>.<sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> That is why many countries have set in place regulations to improve "good" ozone and prevent the increase of "bad" ozone in urban or residential areas. In terms of ozone protection (the preservation of "good" ozone) the <a href="European_Union" title="European Union">European Union</a> has strict guidelines on what products are allowed to be bought, distributed, or used in specific areas.<sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> With effective regulation, the ozone is expected to heal over time.<sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup>
</p>

<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="Ozone_depletion_and_climate_change" title="Ozone depletion and climate change">Ozone depletion and climate change</a></div>
<p>In 1978, the United States, Canada, and <a href="Norway" title="Norway">Norway</a> enacted bans on <a href="Chlorofluorocarbon" title="Chlorofluorocarbon">CFC</a>-containing <a href="Aerosol_spray" class="mw-redirect" title="Aerosol spray">aerosol sprays</a> that damage the ozone layer but the European Community rejected a similar proposal. In the U.S., chlorofluorocarbons continued to be used in other applications, such as refrigeration and industrial cleaning, until after the discovery of the Antarctic ozone hole in 1985. After negotiation of an international treaty (the <a href="Montreal_Protocol" title="Montreal Protocol">Montreal Protocol</a>), CFC production was capped at 1986 levels with commitments to long-term reductions.<sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> This allowed for a ten-year phase-in for developing countries<sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> (identified in Article 5 of the protocol). Since then, the treaty was amended to ban CFC production after 1995 in developed countries, and later in developing countries.<sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> All of the world's 197 countries have signed the treaty. Beginning January 1, 1996, only recycled or stockpiled CFCs were available for use in developed countries like the US. The production phaseout was possible because of efforts to ensure that there would be substitute chemicals and technologies for all ODS uses.<sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup>
</p><p>On August 2, 2003, scientists announced that the global depletion of the ozone layer might be slowing because of the international regulation of ozone-depleting substances. In a study organized by the <a href="American_Geophysical_Union" title="American Geophysical Union">American Geophysical Union</a>, three satellites and three ground stations confirmed that the upper-atmosphere ozone-depletion rate slowed significantly over the previous decade. Some breakdown was expected to continue because of ODSs used by nations which have not banned them, and because of gases already in the stratosphere. Some ODSs, including CFCs, have very long atmospheric lifetimes ranging from 50 to over 100 years. It has been estimated that the ozone layer will recover to 1980 levels near the middle of the 21st century.<sup id="cite_ref-wmo2010_27-0" class="reference"><a href="#cite_note-wmo2010-27"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup> A gradual trend toward "healing" was reported in 2016.<sup id="cite_ref-healing_28-0" class="reference"><a href="#cite_note-healing-28"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup>
</p><p>Compounds containing <a href="Carbon%E2%80%93hydrogen_bond" title="Carbon–hydrogen bond">C–H bonds</a> (such as <a href="Hydrochlorofluorocarbon" class="mw-redirect" title="Hydrochlorofluorocarbon">hydrochlorofluorocarbons</a>, or HCFCs) have been designed to replace CFCs in certain applications. These replacement compounds are more reactive and less likely to survive long enough in the atmosphere to reach the stratosphere where they could affect the ozone layer. While being less damaging than CFCs, HCFCs can have a negative impact on the ozone layer, so they are also being phased out.<sup id="cite_ref-29" class="reference"><a href="#cite_note-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> These in turn are being replaced by <a href="Hydrofluorocarbon" title="Hydrofluorocarbon">hydrofluorocarbons</a> (HFCs) and other compounds that do not destroy stratospheric ozone at all.
</p><p>The residual effects of CFCs accumulating within the atmosphere lead to a concentration gradient between the atmosphere and the ocean. This organohalogen compound dissolves into the ocean's surface waters and acts as a <a href="Chlorofluorocarbon" title="Chlorofluorocarbon">time-dependent tracer</a>. This tracer helps scientists study ocean circulation by tracing biological, physical, and chemical pathways.<sup id="cite_ref-30" class="reference"><a href="#cite_note-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup>
</p>
<div class="mw-heading mw-heading2"><h2 id="Implications_for_astronomy">Implications for astronomy</h2></div>
<p>As ozone in the atmosphere prevents most energetic ultraviolet radiation reaching the surface of the Earth, astronomical data in these wavelengths have to be gathered from satellites orbiting above the atmosphere and ozone layer. Most of the light from young hot stars is in the ultraviolet and so study of these wavelengths is important for studying the origins of galaxies. The Galaxy Evolution Explorer, <a href="GALEX" title="GALEX">GALEX</a>, is an orbiting ultraviolet space telescope launched on April 28, 2003, which operated until early 2012.<sup id="cite_ref-31" class="reference"><a href="#cite_note-31"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup>
</p>
<ul class="center gallery mw-gallery-traditional">
<li class="gallerybox" style="width: 335px">
<div class="thumb" style="width: 330px; height: 290px;"><span typeof="mw:File"></span></div>
<div class="gallerytext">This <a href="GALEX" title="GALEX">GALEX</a> image of the <a href="Cygnus_Loop" title="Cygnus Loop">Cygnus Loop nebula</a> could not have been taken from the surface of the Earth because the ozone layer blocks the ultra-violet radiation emitted by the nebula.</div>
</li>
</ul>
<div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2></div>
<ul><li><a href="Cambrian_explosion" title="Cambrian explosion">Cambrian explosion</a></li>
<li><a href="Nuclear_winter" title="Nuclear winter">Nuclear winter</a></li>
<li><a href="Oxygen" title="Oxygen">Oxygen</a></li>
<li><a href="Short-lived_climate_pollutants" class="mw-redirect" title="Short-lived climate pollutants">Short-lived climate pollutants</a></li>
<li><a href="United_Nations_Environment_Programme" title="United Nations Environment Programme">United Nations Environment Programme</a></li></ul>
<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>
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<li id="cite_note-APH-11"><span class="mw-cite-backlink">^ <a href="#cite_ref-APH_11-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-APH_11-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-APH_11-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-APH_11-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text"><cite id="CITEREFTabin,_Shagoon2008" class="citation book cs1">Tabin, Shagoon (2008). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=QFBmUu1lwzAC"><i>Global Warming: The Effect Of Ozone Depletion</i></a>. APH Publishing. p.&nbsp;194. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a>&nbsp;<bdi>9788131303962</bdi><span class="reference-accessdate">. Retrieved <span class="nowrap">January 12,</span> 2016</span>.</cite></span>
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<li id="cite_note-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-12">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://ozonewatch.gsfc.nasa.gov/facts/SH.html">"Nasa Ozone Watch: Ozone facts"</a>. <i>ozonewatch.gsfc.nasa.gov</i><span class="reference-accessdate">. Retrieved <span class="nowrap">September 16,</span> 2021</span>.</cite></span>
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<li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</a></b></span> <span class="reference-text"><cite id="CITEREFDouglassNewmanSolomon2014" class="citation journal cs1">Douglass, Anne R.; Newman, Paul A.; Solomon, Susan (2014). <a rel="nofollow" class="external text" href="https://physicstoday.scitation.org/doi/pdf/10.1063/PT.3.2449">"The Antarctic ozone hole: An update"</a>. <i>Physics Today</i>. <b>67</b> (7). American Institute of Physics: <span class="nowrap">42–</span>48. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2014PhT....67g..42D">2014PhT....67g..42D</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1063%2FPT.3.2449">10.1063/PT.3.2449</a>. <a href="Hdl_(identifier)" class="mw-redirect" title="Hdl (identifier)">hdl</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://hdl.handle.net/1721.1%2F99159">1721.1/99159</a></span>.</cite></span>
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<li id="cite_note-14"><span class="mw-cite-backlink"><b><a href="#cite_ref-14">^</a></b></span> <span class="reference-text"><cite class="citation book cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20080629032506/http://www.eia.doe.gov/oiaf/1605/archive/gg97rpt/chap5.html">"Halocarbons and Other Gases"</a>. <i>Emissions of Greenhouse Gases in the United States 1996</i>. Energy Information Administration. 1997. Archived from <a rel="nofollow" class="external text" href="http://www.eia.doe.gov/oiaf/1605/archive/gg97rpt/chap5.html">the original</a> on June 29, 2008<span class="reference-accessdate">. Retrieved <span class="nowrap">June 24,</span> 2008</span>.</cite></span>
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<li id="cite_note-15"><span class="mw-cite-backlink"><b><a href="#cite_ref-15">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.noaanews.noaa.gov/stories2009/20090827_ozone.html">"NOAA Study Shows Nitrous Oxide Now Top Ozone-Depleting Emission"</a>. NOAA. August 27, 2009<span class="reference-accessdate">. Retrieved <span class="nowrap">November 8,</span> 2011</span>.</cite></span>
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<li id="cite_note-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-16">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://education.nationalgeographic.org/resource/ozone-layer">"ozone layer | National Geographic Society"</a>. <i>education.nationalgeographic.org</i><span class="reference-accessdate">. Retrieved <span class="nowrap">May 30,</span> 2022</span>.</cite></span>
</li>
<li id="cite_note-17"><span class="mw-cite-backlink"><b><a href="#cite_ref-17">^</a></b></span> <span class="reference-text"><cite id="CITEREFUS_EPA2016" class="citation web cs1">US EPA, OAR (December 14, 2016). <a rel="nofollow" class="external text" href="https://www.epa.gov/ground-level-ozone-pollution/ozone-implementation-regulatory-actions">"Ozone Implementation Regulatory Actions"</a>. <i>epa.gov</i><span class="reference-accessdate">. Retrieved <span class="nowrap">May 30,</span> 2022</span>.</cite></span>
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<li id="cite_note-18"><span class="mw-cite-backlink"><b><a href="#cite_ref-18">^</a></b></span> <span class="reference-text"><cite id="CITEREFUngar2000" class="citation journal cs1">Ungar, Sheldon (July 2000). <span class="id-lock-subscription" title="Paid subscription required"><a rel="nofollow" class="external text" href="https://journals.sagepub.com/doi/10.1088/0963-6625/9/3/306">"Knowledge, ignorance and the popular culture: climate change versus the ozone hole"</a></span>. <i>Public Understanding of Science</i>. <b>9</b> (3): <span class="nowrap">297–</span>312. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1088%2F0963-6625%2F9%2F3%2F306">10.1088/0963-6625/9/3/306</a>. <a href="ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a>&nbsp;<a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0963-6625">0963-6625</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a>&nbsp;<a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:7089937">7089937</a>.</cite></span>
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<li id="cite_note-GeophysResearchLtrs_20240611-19"><span class="mw-cite-backlink">^ <a href="#cite_ref-GeophysResearchLtrs_20240611_19-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-GeophysResearchLtrs_20240611_19-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-GeophysResearchLtrs_20240611_19-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><cite id="CITEREFFerreiraHuangNomuraWang2024" class="citation journal cs1">Ferreira, Jose P.; Huang, Ziyu; Nomura, Ken-ichi; Wang, Joseph (June 11, 2024). <a rel="nofollow" class="external text" href="https://doi.org/10.1029%2F2024GL109280">"Potential Ozone Depletion From Satellite Demise During Atmospheric Reentry in the Era of Mega-Constellations"</a>. <i>Geophysical Research Letters</i>. <b>51</b> (11). <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2024GeoRL..5109280F">2024GeoRL..5109280F</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1029%2F2024GL109280">10.1029/2024GL109280</a></span>.</cite></span>
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<li id="cite_note-21"><span class="mw-cite-backlink"><b><a href="#cite_ref-21">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://ec.europa.eu/clima/eu-action/protection-ozone-layer/ozone-regulation_en">"Ozone Regulation"</a>. <i>ec.europa.eu</i><span class="reference-accessdate">. Retrieved <span class="nowrap">May 30,</span> 2022</span>.</cite></span>
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<li id="cite_note-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-22">^</a></b></span> <span class="reference-text"><cite id="CITEREFUS_EPA2015" class="citation web cs1">US EPA, OAR (July 15, 2015). <a rel="nofollow" class="external text" href="https://www.epa.gov/ozone-layer-protection/international-treaties-and-cooperation-about-protection-stratospheric-ozone">"International Treaties and Cooperation about the Protection of the Stratospheric Ozone Layer"</a>. <i>epa.gov</i><span class="reference-accessdate">. Retrieved <span class="nowrap">May 30,</span> 2022</span>.</cite></span>
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<li id="cite_note-24"><span class="mw-cite-backlink"><b><a href="#cite_ref-24">^</a></b></span> <span class="reference-text">An Interview with Lee Thomas, EPA's 6th Administrator. <a rel="nofollow" class="external text" href="http://www.epaalumni.org/history/video/interview.cfm?id=28">Video</a>, <a rel="nofollow" class="external text" href="https://www.epaalumni.org/userdata/pdf/60740780F5ACB3D5.pdf#page=1">Transcript</a> (see p15). April 19, 2012.</span>
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<li id="cite_note-25"><span class="mw-cite-backlink"><b><a href="#cite_ref-25">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://archive.today/20121211231814/http://www.epa.gov/ozone/intpol/history.html">"Amendments to the Montreal Protocol"</a>. EPA. August 19, 2010. Archived from <a rel="nofollow" class="external text" href="http://www.epa.gov/ozone/intpol/history.html">the original</a> on December 11, 2012<span class="reference-accessdate">. Retrieved <span class="nowrap">March 28,</span> 2011</span>.</cite></span>
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<li id="cite_note-26"><span class="mw-cite-backlink"><b><a href="#cite_ref-26">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/19970418154223/http://www.epa.gov/ozone/science/q_a.html">"Brief Questions and Answers on Ozone Depletion"</a>. EPA. June 28, 2006. Archived from <a rel="nofollow" class="external text" href="http://www.epa.gov/ozone/science/q_a.html">the original</a> on April 18, 1997<span class="reference-accessdate">. Retrieved <span class="nowrap">November 8,</span> 2011</span>.</cite></span>
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<li id="cite_note-wmo2010-27"><span class="mw-cite-backlink"><b><a href="#cite_ref-wmo2010_27-0">^</a></b></span> <span class="reference-text"><cite class="citation book cs1"><a rel="nofollow" class="external text" href="https://acdb-ext.gsfc.nasa.gov/Documents/O3_Assessments/Docs/WMO_2010/Chapter_2.pdf">"Stratospheric Ozone and Surface Ultraviolet Radiation"</a> <span class="cs1-format">(PDF)</span>. <i>Scientific Assessment of Ozone Depletion: 2010</i>. WMO. 2011<span class="reference-accessdate">. Retrieved <span class="nowrap">March 14,</span> 2015</span>.</cite></span>
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<li id="cite_note-healing-28"><span class="mw-cite-backlink"><b><a href="#cite_ref-healing_28-0">^</a></b></span> <span class="reference-text"><cite id="CITEREFSolomonSusan2016" class="citation journal cs1">Solomon, Susan, et&nbsp;al. (June 30, 2016). <a rel="nofollow" class="external text" href="https://doi.org/10.1126%2Fscience.aae0061">"Emergence of healing in the Antarctic ozone layer"</a>. <i>Science</i>. <b>353</b> (6296): <span class="nowrap">269–</span>74. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2016Sci...353..269S">2016Sci...353..269S</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1126%2Fscience.aae0061">10.1126/science.aae0061</a></span>. <a href="Hdl_(identifier)" class="mw-redirect" title="Hdl (identifier)">hdl</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://hdl.handle.net/1721.1%2F107197">1721.1/107197</a></span>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a>&nbsp;<a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/27365314">27365314</a>.</cite></span>
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<li id="cite_note-29"><span class="mw-cite-backlink"><b><a href="#cite_ref-29">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/19970418133745/http://www.epa.gov/ozone/defns.html#hcfc">"Ozone Depletion Glossary"</a>. EPA. Archived from <a rel="nofollow" class="external text" href="http://www.epa.gov/ozone/defns.html#hcfc">the original</a> on April 18, 1997<span class="reference-accessdate">. Retrieved <span class="nowrap">September 3,</span> 2008</span>.</cite></span>
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<li id="cite_note-30"><span class="mw-cite-backlink"><b><a href="#cite_ref-30">^</a></b></span> <span class="reference-text"><cite id="CITEREFFine2011" class="citation journal cs1">Fine, Rana A. (2011). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20150210212306/http://yyy.rsmas.miami.edu/groups/cfc/pubs/Fine_AnnRevMarineSci3_2011.pdf">"Observations of CFCs and SF6 as Ocean Tracers"</a> <span class="cs1-format">(PDF)</span>. <i>Annual Review of Marine Science</i>. <b>3</b>: <span class="nowrap">173–</span>95. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2011ARMS....3..173F">2011ARMS....3..173F</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1146%2Fannurev.marine.010908.163933">10.1146/annurev.marine.010908.163933</a>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a>&nbsp;<a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/21329203">21329203</a>. Archived from <a rel="nofollow" class="external text" href="http://yyy.rsmas.miami.edu/groups/cfc/pubs/Fine_AnnRevMarineSci3_2011.pdf">the original</a> <span class="cs1-format">(PDF)</span> on February 10, 2015.</cite></span>
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</li>
</ol></div>
<div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2></div>
<dl><dt>Science</dt></dl>
<ul><li><cite id="CITEREFAndersen2015" class="citation journal cs1"><a href="Stephen_O._Andersen" title="Stephen O. Andersen">Andersen, S. O.</a> (2015). <span class="id-lock-subscription" title="Paid subscription required"><a rel="nofollow" class="external text" href="https://link.springer.com/article/10.1007/s13412-014-0213-9">"Lessons from the stratospheric ozone layer protection for climate"</a></span>. <i>Journal of Environmental Studies and Sciences</i>. <b>5</b> (2): <span class="nowrap">143–</span>162. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2015JEnSS...5..143A">2015JEnSS...5..143A</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2Fs13412-014-0213-9">10.1007/s13412-014-0213-9</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a>&nbsp;<a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:129725437">129725437</a>.</cite></li>
<li><cite id="CITEREFAndersenSarmaSinclair2012" class="citation book cs1">Andersen, S.O.; Sarma, K.M.; Sinclair, L. (2012). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=zuesUPcIOq8C"><i>Protecting the Ozone Layer: The United Nations History</i></a>. Taylor &amp; Francis. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a>&nbsp;<bdi>978-1-84977-226-6</bdi>.</cite></li>
<li><a href="Hannah_Ritchie" title="Hannah Ritchie">Ritchie, Hannah</a>, "What We Learned from Acid Rain: By working together, the nations of the world can solve climate change", <i><a href="Scientific_American" title="Scientific American">Scientific American</a></i>, vol. 330, no. 1 (January 2024), pp.&nbsp;75–76. "[C]ountries will act only if they know others are willing to do the same. With <a href="Acid_rain" title="Acid rain">acid rain</a>, they did act collectively.... We did something similar to restore Earth's protective ozone layer.... [T]he cost of technology really matters.... In the past decade the price of <a href="Solar_energy" title="Solar energy">solar energy</a> has fallen by more than 90 percent and that of <a href="Wind_energy" class="mw-redirect" title="Wind energy">wind energy</a> by more than 70 percent. <a href="Electric_battery" title="Electric battery">Battery</a> costs have tumbled by 98 percent since 1990, bringing the price of <a href="Electric_car" title="Electric car">electric cars</a> down with them....[T]he stance of <a href="Elected_official" class="mw-redirect" title="Elected official">elected officials</a> matters more than their <a href="Political_party" title="Political party">party</a> affiliation.... Change can happen – but not on its own. We need to drive it." (p.&nbsp;76.)</li>
<li><a href="United_Nations_Environment_Programme" title="United Nations Environment Programme">United Nations Environment Programme</a> (2010). <i>Environmental Effects of Ozone Depletion and its Interactions with Climate Change: 2010 Assessment</i>. Nairobi: UNEP.</li>
<li><cite id="CITEREFVeldersFaheyDanielMcFarland2009" class="citation journal cs1">Velders, G. J. M.; Fahey, D. W.; Daniel, J. S.; McFarland, M.; Andersen, S. O. (2009). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2700150">"The large contribution of projected HFC emissions to future climate forcing"</a>. <i>Proceedings of the National Academy of Sciences</i>. <b>106</b> (27): <span class="nowrap">10949–</span>10954. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2009PNAS..10610949V">2009PNAS..10610949V</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1073%2Fpnas.0902817106">10.1073/pnas.0902817106</a></span>. <a href="PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a>&nbsp;<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2700150">2700150</a></span>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a>&nbsp;<a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/19549868">19549868</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a>&nbsp;<a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:3743609">3743609</a>.</cite></li>
<li><cite id="CITEREFVeldersAndersenDanielFahey2007" class="citation journal cs1">Velders, Guus J.M.; Andersen, Stephen O.; Daniel, John S.; Fahey, David W.; McFarland, Mack (2007). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1817831">"The Importance of the Montreal Protocol in Protecting Climate"</a>. <i>Proceedings of the National Academy of Sciences of the United States of America</i>. <b>104</b> (12): <span class="nowrap">4814–</span>4819. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2007PNAS..104.4814V">2007PNAS..104.4814V</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1073%2Fpnas.0610328104">10.1073/pnas.0610328104</a></span>. <a href="PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a>&nbsp;<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1817831">1817831</a></span>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a>&nbsp;<a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/17360370">17360370</a>.</cite></li></ul>
<dl><dt>Policy</dt></dl>
<ul><li><cite id="CITEREFZaelkeBorgford-Parnell2015" class="citation journal cs1">Zaelke, Durwood; Borgford-Parnell, Nathan (2015). <span class="id-lock-subscription" title="Paid subscription required"><a rel="nofollow" class="external text" href="https://link.springer.com/article/10.1007%2Fs13412-014-0215-7">"The importance of phasing down hydrofluorocarbons and other short-lived climate pollutants"</a></span>. <i>Journal of Environmental Studies and Sciences</i>. <b>5</b> (2): <span class="nowrap">169–</span>175. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2015JEnSS...5..169Z">2015JEnSS...5..169Z</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2Fs13412-014-0215-7">10.1007/s13412-014-0215-7</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a>&nbsp;<a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:128974741">128974741</a>.</cite></li>
<li><cite id="CITEREFXuZaelkeVeldersRamanathan2013" class="citation journal cs1">Xu, Y.; Zaelke, D.; Velders, G. J. M.; Ramanathan, V. (2013). <a rel="nofollow" class="external text" href="https://acp.copernicus.org/articles/13/6083/2013/acp-13-6083-2013.html">"The role of HFCS in mitigating 21st century climate change"</a>. <i>Atmospheric Chemistry and Physics</i>. <b>13</b> (12): <span class="nowrap">6083–</span>6089. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2013ACP....13.6083X">2013ACP....13.6083X</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.5194%2Facp-13-6083-2013">10.5194/acp-13-6083-2013</a></span>.</cite></li>
<li><cite id="CITEREFMolinaZaelkeSarmaAndersen2009" class="citation journal cs1">Molina, M.; Zaelke, D.; Sarma, K. M.; Andersen, S. O.; Ramanathan, V.; Kaniaru, D. (2009). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2791591">"Reducing abrupt climate change risk using the Montreal Protocol and other regulatory actions to complement cuts in CO2 emissions"</a>. <i>Proceedings of the National Academy of Sciences</i>. <b>106</b> (49): <span class="nowrap">20616–</span>20621. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1073%2Fpnas.0902568106">10.1073/pnas.0902568106</a></span>. <a href="PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a>&nbsp;<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2791591">2791591</a></span>. <a href="PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a>&nbsp;<a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/19822751">19822751</a>. <a href="S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a>&nbsp;<a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:13240115">13240115</a>.</cite></li>
<li><cite id="CITEREFAndersonSarmaTaddonio2007" class="citation book cs1">Anderson, S. O.; Sarma, M. K.; Taddonio, K. (2007). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=OvgA-hZrPOcC"><i>Technology Transfer for the Ozone Layer: Lessons for Climate Change</i></a>. London: Earthscan. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a>&nbsp;<bdi>9781849772846</bdi>.</cite></li>
<li><cite id="CITEREFBenedickWorld_Wildlife_Fund_(U.S.)Institute_for_the_Study_of_Diplomacy._Georgetown_University.1998" class="citation book cs1">Benedick, Richard Elliot; World Wildlife Fund (U.S.); Institute for the Study of Diplomacy. Georgetown University. (1998). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=4yM9uPRUvi4C"><i>Ozone Diplomacy: New Directions in Safeguarding the Planet</i></a> (2nd&nbsp;ed.). Harvard University Press. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a>&nbsp;<bdi>978-0-674-65003-9</bdi>.</cite> (Ambassador Benedick was the Chief U.S. Negotiator at the meetings that resulted in the Montreal Protocol.)</li>
<li><cite id="CITEREFChasekDownieBrown2013" class="citation book cs1">Chasek, P. S.; Downie, David L.; Brown, J. W. (2013). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=Ju41zgEACAAJ"><i>Global Environmental Politics</i></a> (6th&nbsp;ed.). Boulder: Westview Press. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a>&nbsp;<bdi>9780813348971</bdi>.</cite></li>
<li><cite id="CITEREFGrundmann2001" class="citation book cs1">Grundmann, Reiner (2001). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=FYyVDlRhBvEC"><i>Transnational Environmental Policy: Reconstructing Ozone</i></a>. Psychology Press. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a>&nbsp;<bdi>978-0-415-22423-9</bdi>.</cite></li>
<li><cite id="CITEREFParson2003" class="citation book cs1">Parson, E. (2003). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=VNkJCAAAQBAJ"><i>Protecting the Ozone Layer: Science and Strategy</i></a>. Oxford: Oxford University Press. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a>&nbsp;<bdi>9780190288716</bdi>.</cite></li></ul>
<div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2></div>
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<div class="side-box-text plainlist">Wikimedia Commons has media related to <span style="font-weight: bold; font-style: italic;"><a href="https://commons.wikimedia.org/wiki/Category:Ozone_layer" class="extiw external" title="commons:Category:Ozone layer">Ozone layer</a></span>.</div></div>
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<div class="side-box-text plainlist">English <a href="Wikisource" title="Wikisource">Wikisource</a> has original text related to this article:
<div style="margin-left: 10px;"><b><a href="https://en.wikisource.org/wiki/en:Special:Search/Ozone_layer" class="extiw external" title="s:en:Special:Search/Ozone layer">Ozone layer</a></b></div></div></div>
</div>
<ul><li><a rel="nofollow" class="external text" href="http://www.ccpo.odu.edu/SEES/ozone/oz_class.htm">Stratospheric ozone: an electronic textbook</a></li>
<li><a rel="nofollow" class="external text" href="https://archive.today/20040702045343/http://www.unep.org/ozone/Public_Information/4Aii_PublicInfo_Facts_OzoneLayer.asp">Ozone Layer Info</a> (archived July 2, 2004)</li>
<li>The <a rel="nofollow" class="external text" href="http://www.copernicus-stratosphere.eu/">CAMS stratospheric ozone service</a> delivers maps, datasets, and validation reports about the past and current state of the ozone layer.</li></ul>
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</style><div id="Earth&amp;#039;s_atmosphere42" style="font-size:114%;margin:0 4em"><a href="Atmosphere_of_Earth" title="Atmosphere of Earth">Earth's atmosphere</a></div></th></tr><tr><td colspan="2" class="navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">
<ul><li><a href="Troposphere" title="Troposphere">Troposphere</a></li>
<li><a href="Stratosphere" title="Stratosphere">Stratosphere</a></li>
<li><a href="Mesosphere" title="Mesosphere">Mesosphere</a></li>
<li><a href="Thermosphere" title="Thermosphere">Thermosphere</a></li>
<li><a href="Exosphere" title="Exosphere">Exosphere</a></li></ul>
</div></td></tr><tr><td colspan="2" class="navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">
<ul><li><a href="Tropopause" title="Tropopause">Tropopause</a></li>
<li><a href="Stratopause" title="Stratopause">Stratopause</a></li>
<li><a href="Mesopause" title="Mesopause">Mesopause</a></li>
<li><a href="Thermopause" title="Thermopause">Thermopause</a> / <a href="Exobase" class="mw-redirect" title="Exobase">Exobase</a></li></ul>
</div></td></tr><tr><td colspan="2" class="navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">
<ul>
<li><a href="Turbopause" title="Turbopause">Turbopause</a></li>
<li><a href="Ionosphere" title="Ionosphere">Ionosphere</a></li></ul>
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</style></div><div role="navigation" class="navbox authority-control" aria-labelledby="Authority_control_databases_frameless&amp;#124;text-top&amp;#124;10px&amp;#124;alt=Edit_this_at_Wikidata&amp;#124;link=https&amp;#58;//www.wikidata.org/wiki/Q79995#identifiers&amp;#124;class=noprint&amp;#124;Edit_this_at_Wikidata1968" style="padding:3px"><table class="nowraplinks hlist mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="Authority_control_databases_frameless&amp;#124;text-top&amp;#124;10px&amp;#124;alt=Edit_this_at_Wikidata&amp;#124;link=https&amp;#58;//www.wikidata.org/wiki/Q79995#identifiers&amp;#124;class=noprint&amp;#124;Edit_this_at_Wikidata1968" style="font-size:114%;margin:0 4em">Authority control databases </div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">International</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"><ul><li><span class="uid"><a rel="nofollow" class="external text" href="https://id.worldcat.org/fast/1049758">FAST</a></span></li></ul></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">National</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"><ul><li><span class="uid"><a rel="nofollow" class="external text" href="https://d-nb.info/gnd/4130365-9">Germany</a></span></li><li><span class="uid"><a rel="nofollow" class="external text" href="https://id.loc.gov/authorities/sh88004695">United States</a></span></li><li><span class="uid"><a rel="nofollow" class="external text" href="https://catalogue.bnf.fr/ark:/12148/cb122513315">France</a></span></li><li><span class="uid"><a rel="nofollow" class="external text" href="https://data.bnf.fr/ark:/12148/cb122513315">BnF data</a></span></li><li><span class="uid"><a rel="nofollow" class="external text" href="https://id.ndl.go.jp/auth/ndlna/00576770">Japan</a></span></li><li><span class="uid"><span class="rt-commentedText tooltip tooltip-dotted" title="ozonová vrstva"><a rel="nofollow" class="external text" href="https://aleph.nkp.cz/F/?func=find-c&amp;local_base=aut&amp;ccl_term=ica=ph123891&amp;CON_LNG=ENG">Czech Republic</a></span></span></li><li><span class="uid"><a rel="nofollow" class="external text" href="https://datos.bne.es/resource/XX545363">Spain</a></span></li><li><span class="uid"><a rel="nofollow" class="external text" href="https://www.nli.org.il/en/authorities/987007548821005171">Israel</a></span></li></ul></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"><ul><li><span class="uid"><span class="rt-commentedText tooltip tooltip-dotted" title="Couche d'ozone"><a rel="nofollow" class="external text" href="https://www.idref.fr/031265022">IdRef</a></span></span><ul><li><span class="uid"><span class="rt-commentedText tooltip tooltip-dotted" title="Ozone stratosphérique"><a rel="nofollow" class="external text" href="https://www.idref.fr/171872975">2</a></span></span></li></ul></li><li><span class="uid"><a rel="nofollow" class="external text" href="https://catalog.archives.gov/id/10643008">NARA</a></span></li><li><span class="uid"><a rel="nofollow" class="external text" href="https://lux.collections.yale.edu/view/concept/7dd47b84-fc9d-4740-bc77-078e9d53c82c">Yale LUX</a></span></li></ul></div></td></tr></tbody></table></div></div><!--htdig_noindex--><div><div class="zim-footer">
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