"instrument to observe and study the response of the atmosphere to increased greenhouse gases. The instrument can detect carbon monoxide emissions from the burning of plant materials and animal waste by humans in rainforests and large cities. It can follow giant plumes of this gas moving across the planet from these large burns, allowing scientists to better monitor pollution transport patterns. AIRS provides a global daily 3-D view of Earth's ozone layer, showing how ozone is transported. The instrument also gives scientists their best view of atmospheric ozone in the Antarctic region during the polar winter. AIRS is also able"
"damage plant life on land and in the ocean. Some of the main pollutants that are harmful to the stratosphere are called chlorofluorocarbons (CFCs). They come from aerosols such as hairspray, air conditioners, and some other types. They were banned in the 1970s. In the 1980s, scientists found that there were holes in the ozone around the South Pole. As a result, over 190 countries, including the United States, signed the 1987 Montreal Protocol. This agreement is designated to eliminating chemicals that harm the stratosphere. The 1990 Clean Air Act ""phased out"" the most harmful chemicals and in 1996, production"
"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. These in turn are being replaced by hydrofluorocarbons (HFCs) and other compounds that do not destroy stratospheric ozone at all. The residual effects of CFCs accumulating within the atmosphere lead to a concentration gradient between the atmosphere and the ocean. This organohalogen compound is able to dissolve into the"
"stratosphere was discovered to be declining, mostly because of increasing concentrations of chlorofluorocarbons (CFC) and similar chlorinated and brominated organic molecules. The concern over the health effects of the decline led to the 1987 Montreal Protocol, the ban on the production of many ozone depleting chemicals and in the first and second decade of the 21st Century the beginning of the recovery of stratospheric ozone concentrations. Ozone in the ozone layer filters out sunlight wavelengths from about 200 nm UV rays to 315 nm, with ozone peak absorption at about 250 nm. This ozone UV absorption is important to life,"
"human health. A 2015 report by the U. S. Environmental Protection Agency estimates that the protection of the ozone layer under the treaty will prevent over 280 million cases of skin cancer, 1.5 million skin cancer deaths, and 45 million cataracts in the United States. However, the hydrochlorofluorocarbons, or HCFCs, and hydrofluorocarbons, or HFCs, are now thought to contribute to anthropogenic global warming. On a molecule-for-molecule basis, these compounds are up to 10,000 times more potent greenhouse gases than carbon dioxide. The Montreal Protocol currently calls for a complete phase-out of HCFCs by 2030, but does not place any restriction"
"from the sun. Chlorofluorocarbons (CFCs), which were used beginning in the 1930s in a number of important areas, were determined in 1974 to be responsible for much of the depletion of the ozone layer. Four years later, the EPA and FDA banned CFCs in aerosol cans. As research in the 1980s indicated that the problem was worse than before, and revealed a controversial massive hole in the ozone layer over Antarctica, three international agreements were made to reduce the ozone-damaging substances- the Vienna Convention, the 1987 Montreal Protocol, and a third agreement in 1990 in London. In the United States,"
"and production of chemicals that harm the Earth’s stratospheric ozone layer. This ozone layer protects against harmful ultraviolet B sunlight linked to several medical conditions including cataracts and skin cancer. The ozone-destroying chemicals were classified into two groups, Class I and Class II. Class I consists of substances, including chlorofluorocarbons, that have an ozone depletion potential (ODP) (HL) of 0.2 or higher. Class II lists substances, including hydro chlorofluorocarbons, that are known to or may be detrimental to the stratosphere. Both groups have a timeline for phase-out: Title VI establishes methods for preventing harmful chemicals from entering the stratosphere in"
"1,1,2-Trichloro-1,2,2-trifluoroethane Trichlorotrifluoroethane, also called 1,1,2-Trichloro-1,2,2-trifluoroethane or CFC-113 is a chlorofluorocarbon. It has the formula ClFC-CClF. This colorless, volatile liquid is a versatile solvent. It has attracted much attention for its role in the depletion of stratospheric ozone. The amount of CFC-113 in the atmosphere has remained at about 80 parts per trillion, since the early 1990s. It is isomeric with 1,1,1-Trichloro-2,2,2-trifluoroethane, known as CFC-113a, which has the structural formula CF-CCl. The Montreal Protocol in 1987 called for the phase out of all CFC’s, including CFC-113 by 2010. CFC-113 is a very unreactive chlorofluorocarbon. It remains in the atmosphere about 90"
"of irradiance changes and has, via a dynamic coupling between the stratosphere and troposphere, a significant impact on climate. As with carbon dioxide and methane, there are some natural sources of tropospheric chlorine, such as sea spray. Chlorine from ocean spray is soluble and thus is washed by rainfall before it reaches the stratosphere. It is ""stratospheric"" chlorine that affects ozone depletion. Only methyl chloride, which is one of the halocarbons, has a mainly natural source, and it is responsible for about 20% of the chlorine in the stratosphere; the remaining 80% comes from man-made sources. Chlorofluorocarbons, in contrast, are"
"significant risks and dangers to health and the environment. CFCs and HCFCs (hydrochlorofluorocarbon) deplete the ozone layer and are potent greenhouse gases. HFCs are potent greenhouse gases and are facing calls for stricter international regulation and phase out schedules as a fast-acting greenhouse emission abatement measure, as are perfluorocarbons (PFCs), and sulphur hexafluoride (SF). Because of the compound's effect on climate, the G-20 major economies agreed in 2013 to support initiatives to phase out use of HCFCs. They affirmed the roles of the Montreal Protocol and the United Nations Framework Convention on Climate Change in global HCFC accounting and reduction."
"understanding of the processes that maintained or destroyed it. They were pretty sure they understood how the layer formed, and they knew from laboratory experiments that halogens could destroy ozone. Finally, weather balloons had revealed that the concentration of ozone in the atmosphere changed over time, and scientists suspected weather phenomena or seasonal change were responsible. But how all of these pieces of information worked together on a global scale was still unclear. Scientists conducted experiments from NASA experimental aircraft and proved that atmospheric chemicals such as the chlorofluorocarbons (CFCs) released from refrigerants and aerosol sprays did destroy ozone. As"
"of hydrochlorofluorocarbons entirely by 2020 in a United Nations-sponsored Montreal summit. Developing nations were given until 2030. Many nations, such as the United States and China, who had previously resisted such efforts, agreed with the accelerated phase out schedule. Work on alternatives for chlorofluorocarbons in refrigerants began in the late 1970s after the first warnings of damage to stratospheric ozone were published. The hydrochlorofluorocarbons (HCFCs) are less stable in the lower atmosphere, enabling them to break down before reaching the ozone layer. Nevertheless, a significant fraction of the HCFCs do break down in the stratosphere and they have contributed to"
"harmful effects that hydrochlorofluorocarbons (HCFC) and chlorofluorocarbons (CFC) have on the ozone layer and global warming. Researchers have focused on using new mixtures that have the same properties as past refrigerants to phase out harmful halogenated substances, in accordance to the Montreal Protocol and Kyoto Protocol. For example, researchers found that zeotropic mixture R-404A can replace R-12, a CFC, in household refrigerators. However, there are some technical difficulties for using zeotropic mixtures. This includes leakages, as well as the high temperature glide associated with substances of different boiling points, though the temperature glide can be matched to the temperature difference"
"Chlorofluorocarbon Chlorofluorocarbons (CFCs) are fully halogenated paraffin hydrocarbons that contain only carbon (С), chlorine (Cl), and fluorine (F), produced as volatile derivative of methane, ethane, and propane. They are also commonly known by the DuPont brand name Freon. The most common representative is dichlorodifluoromethane (R-12 or Freon-12). Many CFCs have been widely used as refrigerants, propellants (in aerosol applications), and solvents. Because CFCs contribute to ozone depletion in the upper atmosphere, the manufacture of such compounds has been phased out under the Montreal Protocol, and they are being replaced with other products such as hydrofluorocarbons (HFCs) (e.g., R-410A) and R-134a."
"of the / ratio and of neon, krypton and xenon, have been used to infer the thickness of the firn layer, and determine other palaeoclimatic information such as past mean ocean temperatures. Some gases such as helium can rapidly diffuse through ice, so it may be necessary to test for these ""fugitive gases"" within minutes of the core being retrieved to obtain accurate data. Chlorofluorocarbons (CFCs), which contribute to the greenhouse effect and also cause ozone loss in the stratosphere, can be detected in ice cores after about 1950; almost all CFCs in the atmosphere were created by human activity."
"insoluble and long-lived, allowing them to reach the stratosphere. In the lower atmosphere, there is much more chlorine from CFCs and related haloalkanes than there is in hydrogen chloride from salt spray, and in the stratosphere halocarbons are dominant. The same radiative forcing that produces global warming is expected to cool the stratosphere. This cooling, in turn, is expected to produce a relative ""increase"" in ozone () depletion in the polar area and in the frequency of ozone holes. Conversely, ozone depletion represents a radiative forcing of the climate system of about −0.15 ± 0.10 watts per square metre (W/m)."
"larger than man-made ones."" While strictly true, ""tropospheric"" chlorine is irrelevant; it is ""stratospheric"" chlorine that affects ozone depletion. Chlorine from ocean spray is soluble and thus is washed by rainfall before it reaches the stratosphere. CFCs, in contrast, are insoluble and long-lived, allowing them to reach the stratosphere. In the lower atmosphere, there is much more chlorine from CFCs and related haloalkanes than there is in HCl from salt spray, and in the stratosphere halocarbons are dominant. Only methyl chloride, which is one of these halocarbons, has a mainly natural source, and it is responsible for about 20 percent"
"Dichlorofluoromethane Dichlorofluoromethane or Freon 21 or R 21 is a halomethane or hydrochlorofluorocarbon. It is a colorless and odorless gas. Its critical point is at 178.5 °C (451.7 K) and 5.17 MPa (51.7 bar). At temperatures from 5 K to 105 K it has one phase in the space group Pbca. Dichlorofluoromethane was used as a propellant and refrigerant, but due to its ozone depletion it has been set to be phased out. It has ozone depletion potential 0.04. Production and consumption has been since 2004 reduced to 15% of level from 1989 and it is to be phased out"
"replaced, such as sulfur dioxide. Haloalkanes are also an order(s) of magnitude more expensive than petroleum derived flammable alkanes of similar or better cooling performance. Unfortunately, chlorine- and fluorine-bearing refrigerants reach the upper atmosphere when they escape. In the stratosphere, CFCs break up due to UV radiation, releasing their chlorine free radicals. These chlorine free radicals act as catalysts in the breakdown of ozone through chain reactions. One CFC molecule can cause thousands of ozone molecules to break down. This causes severe damage to the ozone layer that shields the Earth's surface from the Sun's strong UV radiation, and has"
"in 2015 according to Montreal Protocol. Dichlorofluoromethane Dichlorofluoromethane or Freon 21 or R 21 is a halomethane or hydrochlorofluorocarbon. It is a colorless and odorless gas. Its critical point is at 178.5 °C (451.7 K) and 5.17 MPa (51.7 bar). At temperatures from 5 K to 105 K it has one phase in the space group Pbca. Dichlorofluoromethane was used as a propellant and refrigerant, but due to its ozone depletion it has been set to be phased out. It has ozone depletion potential 0.04. Production and consumption has been since 2004 reduced to 15% of level from 1989 and"
"1973, the chemists Frank Sherwood Rowland and Mario Molina, who were then at the University of California, Irvine, began studying the impacts of CFCs in the Earth's atmosphere. They discovered that CFC molecules were stable enough to remain in the atmosphere until they got up into the middle of the stratosphere where they would finally (after an average of 50–100 years for two common CFCs) be broken down by ultraviolet radiation releasing a chlorine atom. Rowland and Molina then proposed that these chlorine atoms might be expected to cause the breakdown of large amounts of ozone (O) in the stratosphere."
"1994 Assessment overestimated ozone loss for the 1994–1997 period. Chlorofluorocarbons (CFCs) and other halogenated ozone depleting substances (ODS) are mainly responsible for man-made chemical ozone depletion. The total amount of effective halogens (chlorine and bromine) in the stratosphere can be calculated and are known as the equivalent effective stratospheric chlorine (EESC). CFCs were invented by Thomas Midgley, Jr. in the 1930s. They were used in air conditioning and cooling units, as aerosol spray propellants prior to the 1970s, and in the cleaning processes of delicate electronic equipment. They also occur as by-products of some chemical processes. No significant natural sources"
"reaction with oxygen atoms or ozone. In addition, solar proton events can significantly affect ozone levels via radiolysis with the subsequent formation of OH . Laughing gas or nitrous oxide (NO) is produced by biological activity at the surface and is oxidised to NO in the stratosphere; the so-called NOx radical cycles also deplete stratospheric ozone. Finally, chlorofluorocarbon molecules are photolysed in the stratosphere releasing chlorine atoms that react with ozone giving ClO and O. The chlorine atoms are recycled when ClO reacts with O in the upper stratosphere, or when ClO reacts with itself in the chemistry of the"
"1,2-Dichlorotetrafluoroethane 1,2-Dichlorotetrafluoroethane, or R-114, also known as cryofluorane (INN), is a chlorofluorocarbon (CFC) with the molecular formula ClFCCFCl. Its primary use has been as a refrigerant. It is a non-flammable gas with a sweetish, chloroform-like odor with the critical point occurring at 145.6 °C and 3.26 MPa. When pressurized or cooled, it is a colorless liquid. It is listed on the Intergovernmental Panel on Climate Change's list of ozone depleting chemicals, and is classified as a Montreal Protocol Class I, group 1 ozone depleting substance. When used as a refrigerant, R-114 is classified as a medium pressure refrigerant. The US"
"greenhouse effect. Conversely, the low concentration of CFCs allow their effects to increase linearly with mass. Because the time history of CFC concentrations in the atmosphere is relatively well known, they have provided an important constraint on ocean circulation. CFCs dissolve in seawater at the ocean surface and are subsequently transported into the ocean interior. Because CFCs are inert, their concentration in the ocean interior reflects simply the convolution of their atmospheric time evolution and ocean circulation and mixing. Chlorofluorocarbons (CFCs) are anthropogenic compounds that have been released into the atmosphere since the 1930s in various applications such as in"
"the Earth's natural stratospheric ozone layer that shields the biosphere against solar UV radiation; increased UV levels at the surface can cause skin cancer or even blindness. CFC-113 was one of the many CFCs that were produced to eliminate toxic and flammable substances in the areas that they were used. It has been used as a cooling agent in refrigerants and air conditioners, aerosol propellant, and a cleansing agent for electrical and electronic components. CFC-113 is one of the three most popular CFCs, along with CFC-11 and CFC-12 and saw much use in its time. CFC-113 is a refrigerant used"
"by 2050. Tropospheric or ground-level ozone (O3) is the ozone present in the lowest portion of the atmosphere (up to 10–15 km above the ground). It is responsible for a large part of the human enhancement of the global greenhouse effect and has a lifetime of a few days to a few weeks. It is not directly emitted but formed by sunlight-driven oxidation of other agents, called ozone precursors, in particular methane (CH4) but also carbon monoxide (CO), non-methane volatile organic compounds (NMVOCs) and nitrogen oxides (NOX). Tropospheric ozone is a harmful pollutant that has detrimental impacts on human health"
"American and European weather. Agricultural crops failed and livestock died in much of the Northern Hemisphere, resulting in one of the worst famines of the 19th century. The freezing winter of 1740–41, which led to widespread famine in northern Europe, may also owe its origins to a volcanic eruption. Sulfate aerosols promote complex chemical reactions on their surfaces that alter chlorine and nitrogen chemical species in the stratosphere. This effect, together with increased stratospheric chlorine levels from chlorofluorocarbon pollution, generates chlorine monoxide (ClO), which destroys ozone (O). As the aerosols grow and coagulate, they settle down into the upper troposphere"
"and refrigerators. But from the 1980s CFCs began to lose favor as refrigerant when their damaging effects on the ozone layer were discovered. Two alternative types of refrigerant, hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs), also lost favour when they were identified as greenhouse gases (additionally, HCFCs were found to be more damaging to the ozone layer than originally thought). The Vienna Convention for the Protection of the Ozone Layer, the Montreal Protocol and the Kyoto Protocol call for the complete abandonment of such refrigerants by 2030. In 1989, amid international concern about the effects of chlorofluorocarbons and hydrochlorofluorocarbons on the ozone"
"(Second Assessment Report), 2001 (Third Assessment Report), 2007 (Fourth Assessment Report), and 2013/2014 (Fifth Assessment Report). Since the 1990s, research on climate change has expanded and grown, linking many fields such as atmospheric sciences, numerical modeling, behavioral sciences, geology and economics, or security. Methane: In 1859, John Tyndall determined that coal gas, a mix of methane and other gases, strongly absorbed infrared radiation. Methane was subsequently detected in the atmosphere in 1948, and in the 1980s scientists realized that human emissions were having a substantial impact. Chlorofluorocarbon: In 1973, British scientist James Lovelock speculated that chlorofluorocarbons (CFCs) could have a"
"ozone layer of Earth's atmosphere during the extraction process, where they accelerate the impacts of climate change. Furthermore, air contaminants like nitrogen oxides, carbon monoxide, formaldehydes, and hydrogen sulfide that are released during drilling have been shown to cause harmful effects ranging from cancer, organ failure, neurological issues, to birth defects. In 2015, a study revealed that there are forty-five fracking sites within 1.5 miles of one junior high in the town of Shafter, one of California's top ten most polluted communities. The students of this community suffer from the state's decision to allow oil companies to continue hydraulic fracturing"
"the Keele Valley Landfill was operated by the City of Toronto from 1983 until 2002, when it was closed because it was full. Chlorofluorocarbons (CFCs), the gas propellants used in aerosol spray cans, became a target for environmental concern in the 1970s and 1980s when research demonstrated that they had a harmful effect on the ozone layer in the atmosphere. The international Montreal Protocol of 1989 banned the use of these substances and they were subsequently replaced with volatile hydrocarbons. The problem with choice to reuse is still not available. There are many products that don't need to be recycled"
"of the SF partial pressure to a CFC partial pressure. According to their material safety data sheets, CFCs and HCFCs are colorless, volatile, toxic liquids and gases with a faintly sweet ethereal odor. Overexposure at concentrations of 11% or more may cause dizziness, loss of concentration, central nervous system depression and/or cardiac arrhythmia. Vapors displace air and can cause asphyxiation in confined spaces. Although non-flammable, their combustion products include hydrofluoric acid, and related species. Normal occupational exposure is rated at 0.07% and does not pose any serious health risks. Chlorofluorocarbon Chlorofluorocarbons (CFCs) are fully halogenated paraffin hydrocarbons that contain only"