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Encyclopedia > Ozone hole
Download high resolution version (1120x1120, 156 KB)Image of the largest Antarctic ozone hole ever recorded in September 2000. Data taken by the Total Ozone Mapping Spectrometer (TOMS) instrument aboard NASAs Earth Probe satellite. File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev...
Download high resolution version (1120x1120, 156 KB)Image of the largest Antarctic ozone hole ever recorded in September 2000. Data taken by the Total Ozone Mapping Spectrometer (TOMS) instrument aboard NASAs Earth Probe satellite. File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev... Enlarge
Image of the largest antarctic ozone hole ever recorded in September 2000. Data taken by the Total Ozone Mapping Spectrometer (TOMS) instrument aboard NASA's Earth Probe satellite.

Ozone depletion refers to the phenomenon of reductions in the amount of Ozone (O3) is an allotrope of oxygen, the molecule consisting of three oxygen atoms instead of the more stable diatomic O2. At standard temperature and pressure ozone is a blue gas. Ozone forms a dark blue liquid, below -112 °C, and a dark blue solid, below -193 °C... ozone in the The stratosphere is the layer of Earths atmosphere which, at the equator, is situated between about 17 km and 50 km altitude above the surface, while at the poles it starts at about 8 km altitude due to the lower tropopause height caused by the lower tropospheric temperature there... stratosphere. There was a reduction of approximately 5% detected from 1979 is a common year starting on Monday. Events January January 1 - United States and the Peoples Republic of China establish diplomatic relations January 4 - State of Ohio agrees to pay $675,000 to families of dead and injured in Kent State University shootings. January 7 - Vietnam and Vietnam... 1979 to 1990 is a common year starting on Monday of the Gregorian calendar. Events 1990 in video gaming January January 3 - Former leader of Panama Manuel Noriega surrenders to American forces. January 7 - The Leaning Tower of Pisa is closed to the public due to safety concerns. January 9 - Lt Gen... 1990. Since the The ozone layer is that part of the Earths stratosphere which contains relatively high concentrations of ozone. The total quantity of ozone in the ozone layer is not very large; if just the ozone were compressed to the pressure of the air at sea level, it would be only... ozone layer prevents most harmful wavelengths of Ultraviolet (UV) radiation is electromagnetic radiation of a wavelength shorter than that of the visible region, but longer than that of soft X-rays. It can be subdivided into near UV (380–200 nm wavelength) and extreme or vacuum UV (200–10 nm). When considering the effects of... ultraviolet light from passing through the Earths atmosphere is the layer of gases surrounding the planet Earth and retained by the Earths gravity. It contains about four-fifths nitrogen and one-fifth oxygen, with trace amounts of other gases. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation and reducing temperature extremes... Earth's atmosphere, observed and projected decreases in ozone have generated worldwide concern and led to adoption of the The Montreal Protocol on Substances That Deplete the Ozone Layer is an international treaty designed to protect the ozone layer from depletion by phasing out the production of a number of substances believed to be responsible for ozone depletion. The treaty was opened for signature on September 16, 1987 and... Montreal Protocol banning the use of chlorofluorocarbon ( CFC molecules CFCs (chlorofluorocarbons) are a family of artificial chemical compounds containing chlorine, fluorine and carbon. They were formerly used widely in industry, for example as refrigerants, propellants and cleaning solvents. Their use has been generally prohibited by the Montreal Protocol, because of fears of their possible destructive effects on... CFC) compounds, as well as other ozone depleting chemicals such as Carbon tetrachloride CCl4 is a synthetic chemical compound formerly widely used in fire extinguishers and refrigeration, but now largely abandoned due to its toxicity. Its IUPAC name is tetrachloromethane. It is a clear liquid with a sweet smell that can be detected at low levels. It is also called carbon... carbon tetrachloride, trichloroethane (also known as methyl chloroform), and bromine compounds known as Halons are a group of compounds obtained by replacing the hydrogen atoms of a hydrocarbon with halogen atoms, such as bromine or fluorine. Halon 1211 is bromochlorodifluoromethane (CF2BrCl) and Halon 1301 is bromotrifluoromethane (CF3Br). Halons are very stable and are widely used in fire extinguishers where water and other alternatives... halons.


Ozone depletion varies geographically and by season. The term ozone hole refers to the annual, temporary reductions in the polar regions, where large losses in ozone occur each spring (up to 70% over 25 million km2 of World map showing location of Antarctica A satellite composite image of Antarctica . Antarctica is the coldest place on earth. Weather patterns rarely penetrate far into the continent, leaving the center cold and dry. There is little precipitation over the continent, but ice there can last for a long time. Nearly... Antarctica and 30% over the The Arctic Ocean, located mostly in the north polar region, is the smallest of the worlds five oceans, and the shallowest. Even though IHO recognizes it as an ocean, oceanographers may call it Fram Basin −4,665 m (according to [2], the Arctic Oceans Eurasian Basin deepest... Arctic) followed by recovery in the summer. This reduction is caused by an increase in concentrations of stratospheric chlorine from breakdown of human manufactured CFC emissions, as well as other gases.


In public policy discussions, the term ozone layer depletion is considered synonymous with the theory that a trend of global ozone depletion, which is mainly caused by CFC emissions, is subsequently allowing more ultraviolet radiation to reach the Earth's surface.


It is suspected that a variety of biological consequences, including, for example, increases in Skin cancer, close-up of level IV melanoma Melanoma is a malignant tumour of melanocytes . Melanocytes predominantly occur in the skin but can be found elsewhere, especially the eye. The vast majority of melanomas originate in the skin. Causes Epidemiologic studies suggest that exposure to ultraviolet radiation is one of... melanoma and the destruction of Photomontage of plankton organisms Plankton is the aggregate community of weakly swimming but mostly drifting small organisms that inhabit the water column of the ocean, seas, and bodies of freshwater. The name comes from the Greek term, —meaning wanderer or drifter. While some forms of plankton can move several... plankton populations in the ocean's The photic zone is the depth of the water, whether in a lake or an ocean, that is exposed to sufficient sunlight for photosynthesis to occur. The depth of the photic zone can be greatly affected by seasonal turbidity. Since the photic zone is the only zone of water where... photic zone, may result from the increased UV exposure due to ozone depletion.

Enlarge
Average area of the ozone hole from 1979 to 2003
Contents

History of the research

In 1970 was a common year starting on Thursday. Events January-February January 1 - Construction begins on Arcosanti, by Paolo Soleri, in Mayer, Arizona, located 65, miles north of Phoenix, Arizona. January 1 - Unix epoch at 00:00:00 UTC. January 12 - Biafra capitulates, ending the Nigerian civil war. January 15... 1970 Prof. Paul J. Crutzen (December 3rd, 1933 - ) is a Dutch nobel prize winning atmospheric chemist. He is best known for his research on ozone depletion. He lists his main research interests as [4] External links His home page Autobiography from nobelprize.org Categories: Stub | Nobel Prize in Chemistry winners ... Paul Crutzen pointed out the possibility that Nitrogen has six different oxides: Nitric oxide (NO) Nitrous oxide (N2O) Nitrogen dioxide (NO2) Dinitrogen trioxide (N2O3) Dinitrogen tetroxide (N2O4) Dinitrogen pentoxide (N2O5) The term nitrogen oxide is imprecise and can be used to refer to any of these or to a mixture of them. A mixture is often formed... nitrogen oxides from Fertilizers are chemicals given to plants with the intention of promoting growth; they are usually applied either via the soil or by foliar spraying. Fertilizers typically provide, in varying proportions, the three major plant nutrients (nitrogen, phosphorus, and potassium), the secondary plant nutrients (calcium, sulfur, magnesium), and sometimes trace elements... fertilizers and Any speed over the speed of sound, which is approximately 343 m/s or 761 mph or 1,225 km/h at sea level, is said to be supersonic. Many modern fighter aircraft are supersonic. The Concorde was a supersonic passenger aircraft, but, since its final retirement flight on November... supersonic An aircraft is any machine capable of atmospheric flight. Categories and classification Aircraft fall into two broad categories: Heavier than air Heavier than air aerodynes, including autogyros, helicopters and variants, and conventional fixed-wing aircraft: ) to provide both lift and thrust. The abbreviation VTOL is applied to aircraft other than... aircraft might deplete the ozone layer.


In 1974 is a common year starting on Tuesday (click on link for calendar). Events January-February January 5 - Dungeons & Dragons officially released. February 4 - Patricia Hearst, the 19 year old granddaughter of publisher William Randolph Hearst, is kidnapped by the Symbionese Liberation Army February 7 - Grenada becomes independent from... 1974 Frank Sherwood Rowland (born June 28, 1927) is a Nobel laureate and a professor of chemistry at the University of California, Irvine. His research is in atmospheric chemistry and chemical kinetics. Born in Delaware, Ohio, Rowland received his B.A. from Ohio Wesleyan University in 1948. He then earned his... Frank Sherwood Rowland and Mario J. Molina (born March 19, 1943) was awarded the 1995 Nobel Prize in Chemistry for his role in elucidating the threat to the Earths ozone layer of chlorofluorocarbon gases (or CFCs). This Nobel Prize was shared with Paul J. Crutzen of UCSD and F. Sherwood Rowland of UC... Mario J. Molina realised that CFC molecules CFCs (chlorofluorocarbons) are a family of artificial chemical compounds containing chlorine, fluorine and carbon. They were formerly used widely in industry, for example as refrigerants, propellants and cleaning solvents. Their use has been generally prohibited by the Montreal Protocol, because of fears of their possible destructive effects on... CFCs, like other gases, act as very efficient In chemistry and biology, catalysis (in Greek meaning the reactants and catalyst are in the same phase. For example acids (H+ ion donors) are common catalysts in many aqueous reactions. In this case both the reactants and the catalysts are in the aqueous phase. In heterogeneous catalysis the catalyst is... catalyzers for the breakup of ozone In science, a molecule is the smallest particle of a pure chemical substance that still retains its chemical composition and properties. A molecule consists of multiple atoms joined by shared pairs of electrons in a is usually confined to chemical compounds, of multiple atoms. A substance that consists of molecules... molecules.


James Ephraim Lovelock (born July 26, 1919), FRS, is an independent scientist, author, researcher and environmentalist who lives in Cornwall, in the west of England. He is most famous for proposing and popularizing the Gaia hypothesis, in which he postulates that the Earth functions as a kind of superorganism (term... James Lovelock (most popularly known as the creator of the Gaia, also spelled as Gaea, Gaïa, or Ge, can refer to any one of the following: Gaia is a Greek and Roman goddess, also known as the Earth Mother. Gaia theory is a group of scientific theories about how life on Earth may regulate the planets biosphere to... Gaia hypothesis) had already discovered, during a cruise in the South Atlantic in 1971 is a common year starting on Friday (click for link to calendar). Events January January 1 - British divorce Reform Act comes into force January 2 - 66 die in stairway crush at Rangers v Celtic football match, Glasgow, Scotland. See Ibrox disaster. January 2 - A ban on television cigarette advertisements... 1971, that almost all of the CFC compounds manufactured since their invention in 1930 is a common year starting on Wednesday. Events January-February January 6 - The first diesel-engine automobile trip is completed (Indianapolis, Indiana, to New York City). January 27 - Miguel Primo de Rivera resigns January 30 - General Damaso Berenquer becomes the new prime minister of Spain February 18 - While studying... 1930 were still present in the atmosphere.


Crutzen, Rowland and Molina received the List of Nobel Prize laureates in Chemistry from 1901 to the present day. 1900s - 1910s - 1920s - 1930s - 1940s - 1950s - 1960s - 1970s - 1980s - 1990s - 2000s 1900s 1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s 2000s External links http://www.nobel.se/chemistry/laureates/index.html Timeline of Nobel Prize Winners... Nobel Prize in Chemistry in 1995 was a common year starting on Sunday of the Gregorian calendar. It was the first year of the Events January January 1 Austria, Finland and Sweden enter the European Union Fred West, accused of mass murder, hangs himself in Winson Green Prison, Birmingham World Trade Organization is established to... 1995 for their work. Based on their work, scientists calculated that if CFC production continued to increase at the going rate of 10% per year until 1990 is a common year starting on Monday of the Gregorian calendar. Events 1990 in video gaming January January 3 - Former leader of Panama Manuel Noriega surrenders to American forces. January 7 - The Leaning Tower of Pisa is closed to the public due to safety concerns. January 9 - Lt Gen... 1990 and then remain steady, CFCs would cause a global ozone loss of 5 to 7% by 1995 was a common year starting on Sunday of the Gregorian calendar. It was the first year of the Events January January 1 Austria, Finland and Sweden enter the European Union Fred West, accused of mass murder, hangs himself in Winson Green Prison, Birmingham World Trade Organization is established to... 1995, and a 30 to 50% loss by Centuries: 20th century - 21st century - 22nd century Decades: 2000s 2010s 2020s 2030s 2040s - 2050s - 2060s 2070s 2080s 2090s 2100s Years: 2045 2046 2047 2048 2049 - 2050 - 2051 2052 2053 2054 2055 Predictions relating to year 2050 U.S. Air Force expects to retire the B-52 Stratofortress. China expected to... 2050. However, the discovery of the Antarctic "ozone hole" by Farman, Gardiner and Shanklin (announced in a paper in still publishes articles across a wide range of scientific fields. Research scientists are the primary audience for the journal, but article summaries in the front of the journal make many of the most important articles accessible for the general public. Also toward the front of each issue are editorials and... Nature in May 1985 is a common year starting on Tuesday of the Gregorian calendar. Events Environmental and weather change Asian Tiger Mosquito, an invasive species is first found in Houston, Texas May 25 - Bangladesh is hit by a tropical cyclone and storm surge which kills approximately 10,000 people. September 19 - 8... 1985) was a surprise. It was found that chemical reactions on Categories: Stub | Clouds ... polar stratospheric clouds (PSCs) in the cold Antarctic stratosphere caused faster depletion than expected, which attracted worldwide publicity.


Satellite measurements showing massive depletion of ozone around the The ceremonial South Pole. Flags of the Antarctic Treaty signatories are arrayed around it, and the Pole Stations old dome is in the background. The polar ice cap and the South Pole station on it are constantly moving relative to the actual, Geographic South Pole. The South Pole is... south pole were becoming available at the same time. However, these were initially rejected as unreasonable by data quality control algorithms (they were filtered out as errors since the values were unexpectedly low); the ozone hole was only detected in satellite data when the raw data was reprocessed following evidence of an ozone hole in in situ observations.


Ozone depletion has been observed all over the globe but is greatest at high Latitude, denoted φ, gives the location of a place on Earth north or south of the Equator. A regions latitude has a great effect on its climate and weather. Latitude is an angular measurement ranging from 0° at the Equator to 90° at the poles. Other latitudes of particular... latitudes (that is, near the poles). The best known example is the annual thinning of the ozone layer over Antarctica during the polar spring (see ozone hole section below).


Since 1981 the Klaus Töpfer, UNEP Exec. Director Headquartered in Nairobi, Kenya, the UN Environment Programme (UNEP) coordinates United Nations environmental activities, assisting developing countries in implementing environmentally sound policies and to encourage sustainable development through sound environmental practices. It was founded on Its activities cover a wide range of issues, from... UNEP has sponsored a series of reports on Scientific Assessment of Ozone Depletion is a sequence of reports sponsored by WMO/UNEP. The most recent is the 2002 report. The reports were set up to inform the Montreal Protocol and amendments about ozone depletion. Findings Changes in Ozone-Depleting Compounds In the troposphere observations show that the total... scientific assessment of ozone depletion. The most recent is from 2002.


Ozone cycle overview

Ozone creation

Ozone (O3) is an allotrope of oxygen, the molecule consisting of three oxygen atoms instead of the more stable diatomic O2. At standard temperature and pressure ozone is a blue gas. Ozone forms a dark blue liquid, below -112 °C, and a dark blue solid, below -193 °C... Ozone in the Earth's atmosphere is generally created by Ultraviolet (UV) radiation is electromagnetic radiation of a wavelength shorter than that of the visible region, but longer than that of soft X-rays. It can be subdivided into near UV (380–200 nm wavelength) and extreme or vacuum UV (200–10 nm). When considering the effects of... ultraviolet light striking General Name, Symbol, Number Oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16 (VIA), 2, p Density, Hardness 1.429 kg/m3, NA Appearance colorless Atomic properties Atomic weight 15.9994 g/mol Atomic radius (calc.) 60 (48) pm Covalent radius 73 pm van der Waals radius 152 pm... oxygen molecules, which consist of two oxygen Properties An atom ( Greek The ). Only the electrons in the outermost orbital (the ), or it can remove electrons from other atoms (an While Democrituss theory has been widely disproven, the recent string theory is based on a similar idea of shape and vibration governing a subatomic particles properties... atoms (O2), creating two single oxygen atoms, known as atomic oxygen. The atomic oxygen then combines with a molecule of O2 to create ozone, O3. The ozone molecule is rather reactive, and when hit by ultraviolet light it splits again into a molecule of O2 and an atom of atomic oxygen, a continuing process called the Ozone-oxygen cycle in the ozone layer. The ozone-oxygen cycle is the process by which ozone is continually regenerated in the Earths stratosphere, all the while converting ultraviolet radiation into heat. The chemistry was worked out by Sidney Chapman in 1930. How ozone is made In the first... ozone-oxygen cycle. Prior to the beginning of the depletion trend, the amount of ozone in the stratosphere was kept even by a stable balance in the amount of creation and destruction of ozone molecules by UV light.


Ozone destruction

Chemical factors

Ozone can be destroyed by atomic General Name, Symbol, Number chlorine, Cl, 17 Series halogens Group, Period, Block 17 (VIIA), 3, p Density, Hardness 3.214 kg/m3 (273 K), NA Appearance yellowish green Atomic properties Atomic weight 35.453 amu Atomic radius (calc.) 100 pm (79) pm Covalent radius 99 pm van der Waals radius... chlorine, General Name, Symbol, Number Fluorine, F, 9 Series Halogens Group, Period, Block 17 (VIIA), 2 , p Density, Hardness 1.696 kg/m3, NA Appearance pale greenish-yellow gas Atomic properties Atomic weight 18.9984 g/mol Atomic radius (calc.) 50 (42) pm Covalent radius 71 pm van der Waals radius... fluorine or General Name, Symbol, Number bromine, Br, 35 Series halogens Group, Period, Block 17 (VIIA), 4, p Density, Hardness 3119 kg/m3 (300 K), NA Appearance Gas: red-brown solid: metallic luster Atomic properties Atomic weight 79.904 amu Atomic radius (calc.) 115 (94) pm Covalent radius 114 pm van der... bromine in the atmosphere. These elements are found in certain stable compounds, especially CFC molecules CFCs (chlorofluorocarbons) are a family of artificial chemical compounds containing chlorine, fluorine and carbon. They were formerly used widely in industry, for example as refrigerants, propellants and cleaning solvents. Their use has been generally prohibited by the Montreal Protocol, because of fears of their possible destructive effects on... chlorofluorocarbons (CFCs), which may find their way to the The stratosphere is the layer of Earths atmosphere which, at the equator, is situated between about 17 km and 50 km altitude above the surface, while at the poles it starts at about 8 km altitude due to the lower tropopause height caused by the lower tropospheric temperature there... stratosphere and there be liberated by the action of ultraviolet light. Most importantly, the chlorine atoms so generated destroy ozone molecules in a In chemistry and biology, catalysis (in Greek meaning the reactants and catalyst are in the same phase. For example acids (H+ ion donors) are common catalysts in many aqueous reactions. In this case both the reactants and the catalysts are in the aqueous phase. In heterogeneous catalysis the catalyst is... catalytic cycle. In this cycle, a chlorine atom reacts with an ozone molecule, taking an oxygen atom with it (forming ClO) and leaving a normal oxygen molecule. A free oxygen atom then takes away the oxygen from the ClO, and the final result is an oxygen molecule and a chlorine atom, which then reinitiates the cycle. A single chlorine atom would keep on destroying ozone forever were it not for reactions that remove them from this cycle by forming reservoir species such as The chemical hydrochloric acid is a highly acidic aqueous solution of hydrogen chloride (HCl). It is highly corrosive liquid (at room temperature and pressure) and should be handled only with appropriate precautions. Hydrochloric acid is a commonly used chemical reagent and is one of the strong acids that ionize completely... hydrochloric acid and chlorine nitrate.


Polar stratospheric clouds

The reactivation of atomic chlorine from these reservoir species is normally slow, but is enhanced by the presence of Categories: Stub | Clouds ... polar stratospheric clouds which appear during Antarctic winters, leading to a strong seasonal cycle in ozone hole formation.


Observations

Enlarge
Global monthly average total ozone amount

The most pronounced decrease in ozone has been in the lower The stratosphere is the layer of Earths atmosphere which, at the equator, is situated between about 17 km and 50 km altitude above the surface, while at the poles it starts at about 8 km altitude due to the lower tropopause height caused by the lower tropospheric temperature there... stratosphere. However, the ozone hole is most usually measured not in terms of ozone concentrations at these levels (which are typically of a few parts per million) but by reduction in the total column ozone, above a point on the Earth's surface, which is normally expressed in Dobson units (DU) are the standard way to express ozone amounts in the atmosphere. One DU is 2.7 × 1016 ozone molecules per square centimetre, or 2.7 × 1020/m². One Dobson unit refers to a layer of ozone that would be 10 micrometre thick under standard temperature and... Dobson units. Marked decreases in column ozone in the Antarctic spring and early summer compared to the early 1970s and before have been observed using instruments such as the Categories: Stub ... Total Ozone Mapping Spectrometer (TOMS) [1] (http://www.atm.ch.cam.ac.uk/tour/part2.html).

Enlarge
Lowest value of ozone measured by Categories: Stub ... TOMS each year in the ozone hole

Substantial reductions of up to 70% in the ozone column observed in the austral (i.e. southern hemispheric) spring over Antarctica and first reported in 1985 (Farman et al 1985) are continuing [2] (http://www.wmo.ch/web/arep/reports/o3_assess_rep_2002_front_page.html). Through the 1990's, total column ozone in September and October have continued to be 40-50% lower than pre-ozone-hole values. In the arctic, declines are greatest in winter/spring and the amount is more variable year-to-year than in the Antarctic: when the stratosphere is colder the losses are greater, up to 30%.


The importance of the reaction on polar stratospheric cloud is many-fold. The PSCs only form in extreme cold; the Antarctic stratosphere is colder than the Arctic; which is why ozone holes first formed over Antarctica and why the Arctic ones are not as deep. The original predictions failed to take PSCs into account, which is why a sudden Antarctic ozone hole, rather than gradual global depletion, was such a surprise.


In middle latitudes it is probably preferable to speak of ozone depletion rather than holes; declines are about 3% below pre-1980 values for 35-60N and about 6% for 35-60S. In the tropics, there are no significant trends.


Ozone depletion also explains much of the observed reduction in stratospheric and upper The troposphere is the lowermost portion of Earths atmosphere and the one in which most weather phenomena occur. The greenhouse effect also occurs in the troposphere. The troposphere starts at the earths surface and extends to an altitude of 16-18 km over tropical regions, decreasing to less... tropospheric temperatures [3]  (http://www.grida.no/climate/ipcc_tar/wg1/223.htm) [4] (http://www.giss.nasa.gov/edu/gwdebate/). This is because the reason for the warmth of the stratosphere is absorption of UV radiation by ozone, hence reduced ozone leads to cooling. Some stratospheric cooling is also predicted from increases in Greenhouse gases are gaseous components of the atmosphere that contribute to the greenhouse effect. The major natural greenhouse gases are water vapor, which in the cloudless case causes (see note below) about 60-70% of the greenhouse effect on Earth, carbon dioxide (about 26%) and ozone. [1] Minor greenhouse gases... greenhouse gases such as Carbon dioxide is an atmospheric gas composed of one carbon and two oxygen atoms. A very widely known chemical compound, it is frequently called by its formula CO2. Carbon dioxide results from the combustion of organic matter if sufficient amounts of oxygen are present. It is also produced by various... CO2; however the ozone-induced cooling is found to be probably dominant.


Predictions of ozone remains a difficult science. The World Meteorological Organization Global Ozone Research and Monitoring Project - Report No. 44 (http://www.al.noaa.gov/WWWHD/Pubdocs/Assessment98/executive-summary.html#A), which on balance comes out strongly in favour of the Montreal protocol, nonetheless notes that projections of ozone loss for the 1994-1997 period made in the Klaus Töpfer, UNEP Exec. Director Headquartered in Nairobi, Kenya, the UN Environment Programme (UNEP) coordinates United Nations environmental activities, assisting developing countries in implementing environmentally sound policies and to encourage sustainable development through sound environmental practices. It was founded on Its activities cover a wide range of issues, from... UNEP 1994 Assessment had been an overestimate.


Chemicals in the atmosphere

CFCs in the atmosphere

CFCs are completely artificial (they did not exist in nature before being synthesized by man). They are used in air conditioning/cooling units, as http://visibleearth.nasa.gov/cgi-bin/viewrecord?10980 Aerosol pollution over Northern India and Bangladesh - NASA Aerosol is a collection of particles suspended in a gas. It consists of both the particles and the gas in which the particles are suspended. The particle size ranges from 0.002 µm to... aerosol propellants prior to the Millennia: 1st millennium - 2nd millennium - 3rd millennium Events and trends Technology Bulletin board system popularity Popularization of personal computers, Walkmans, VHS videocassette recorders, and compact disc (CD) players Introduction of the IBM PC Home video games become enormously popular, most notably Atari until the market crashes in 1983; the rise... 1980s, and in the cleaning processes of delicate electronic equipment, and are a byproduct of some chemical processes. As mentioned in the ozone cycle overview above, when such ozone-depleting chemicals reach the stratosphere, they are dissociated by ultraviolet light to release chlorine atoms. The chlorine atom acts as a A catalyst (Greek: καταλύτης) is a substance that accelerates the rate of a chemical reaction, at some temperature, but without itself being transformed or consumed by the reaction (see also catalysis). A catalyst participates in the reaction but is neither a chemical... catalyst which can break down many thousands of ozone molecules before it is removed from the stratosphere. Given the longevity of CFC molecules, recovery times are measured in decades. It is calculated that a CFC molecule takes an average of 15 years to go from the ground level up to the upper atmosphere, and it can stay there for about a century, destroying up to one hundred thousand ozone molecules during that time.


Verification of observations

Scientists have increasingly been able to attribute the observed ozone depletion to the increase of anthropogenic The halogens are a chemical series. They are the elements in Group 17 (old-style: VII or VIIA) of the periodic table: fluorine, chlorine, bromine, iodine, and astatine. The word comes from Greek roots meaning salt and creator. These elements are diatomic molecules in their natural form. They require one... halogen compounds from CFCs by the use of complex chemical transport models and their validation against observational data (e.g. SLIMCAT  (http://www.lec.leeds.ac.uk/~martyn/slimcat.html)). These models work by combining satellite measurements of chemical concentrations and meteorological fields with chemical reaction rate constants obtained in lab experiments, and are able to identify not only the key chemical reactions but also the transport processes which bring CFC photolysis products into contact with ozone.


The ozone hole and its causes

The Antarctic ozone hole is an area of the antarctic stratosphere in which the recent ozone levels have dropped to as low as 33% of their pre- 1975 was a common year starting on Wednesday (the link is to a full 1975 calendar). Events January January 1 - Watergate scandal: John N. Mitchell, H. R. Haldeman, John D. Ehrlichman are found guilty of the Watergate cover-up and are sentenced to between 30 months and 8 years in... 1975 values. The ozone hole occurs during the Antarctic spring, from September is the ninth month of the year in the Gregorian Calendar and one of four Gregorian months with the length of 30 days. September begins (astrologically) with the sun in the sign of Virgo and ends in the sign of Libra. Astronomically speaking, the sun begins in the constellation... September to early December is the twelfth and last month of the year in the Gregorian Calendar and one of seven Gregorian months with the length of 31 days. December begins (astrologically) with the sun in the sign of Sagittarius and ends in the sign of Capricorn. Astronomically speaking, the sun begins in... December, as strong westerly winds start to circulate around the continent and create an atmospheric container. Within this "polar vortex", over 50% of the lower stratospheric ozone is destroyed during the antarctic spring.[5]  (http://www.nas.nasa.gov/About/Education/Ozone/antarctic.html)


Polar regions get a much larger variation in sunlight than anywhere else, and during the 3 months of winter spend most of time in the dark without solar radiation. Temperatures hover around or below -80'C for much of the winter, which leads to the formation of Categories: Stub | Clouds ... polar stratospheric clouds (PSCs). The cloud particles are composed of nitric acid (Type I PSC) or water ice (Type II PSC); both types provide surfaces for chemical reactions that speed the degradation of ozone molecules.


As explained above, the overall cause of ozone depletion, in the antarctic and elsewher, is the presence of chlorine-containing source gases (primarily CFCs and related halocarbons) which in the presence of UV light are dissociated releasing chlorine atoms which go on to catalyze the destruction of ozone. The Cl-catalyzed ozone depletion can take place in the gas phase, but it is dramatically enhanced in the presence of polar stratospheric clouds. The Photochemistry is the study of the interaction of light and chemicals. The first law of photochemistry, known as the Grotthuss-Draper law (for chemists Christian J.D.T. von Grotthuss and John W. Draper), states that light must be absorbed by a chemical substance in order for a photochemical reaction... photochemical processes involved are complex but well understood. The key observation is that ordinarily, most of the chlorine in the stratosphere resides in stable "reservoir" compounds, primarily hydrogen chloride (HCl) and chlorine nitrate (ClONO2). During the antarctic winter and spring, however, reactions on the surface of the cloud particles convert these reservoir compounds back into reactive free radicals, Cl and ClO. The clouds can also remove NO2 from the atmosphere by converting it to nitric acid, preventing the newly formed ClO from being converted back into ClONO2. The increase of UV light in spring then causes the accumulated reactive Cl compounds to destroy over 17% of the ozone, while bromine compounds deplete another 33%. The role of sunlight in ozone depletion is the reason why the Antarctic ozone depletion is greatest during spring; during winter, even though PSCs are at their most abundant, there is no light over the pole to drive the chemical reactions. Most of the ozone that is destroyed is in the lower stratosphere, in contrast to the much smaller ozone depletion through homogeneous gas phase reactions, which occurs primarily in the upper stratosphere.


Warming temperatures near the end of spring break up the vortex around mid- December is the twelfth and last month of the year in the Gregorian Calendar and one of seven Gregorian months with the length of 31 days. December begins (astrologically) with the sun in the sign of Sagittarius and ends in the sign of Capricorn. Astronomically speaking, the sun begins in... December. As warm, ozone-rich air flows in from lower latitudes, the PSCs are destroyed, the ozone depletion process shuts down, and the ozone hole heals.


Interest in ozone hole

While the effect of the Antarctic hole in decreasing the global ozone is relatively small, estimated at about 4% per decade, the hole has generated a great deal of interest because:

  • The decrease in the ozone layer was predicted in the early 1980's to be roughly 7% over a sixty-year period.
  • The sudden recognition in 1985 is a common year starting on Tuesday of the Gregorian calendar. Events Environmental and weather change Asian Tiger Mosquito, an invasive species is first found in Houston, Texas May 25 - Bangladesh is hit by a tropical cyclone and storm surge which kills approximately 10,000 people. September 19 - 8... 1985 that there was a substantial "hole" was widely reported in the press. The especially rapid ozone depletion in Antarctica had previously been dismissed as measurement error.
  • Many were worried that ozone holes might start to appear over other areas of the globe but to date the only other large-scale depletion is a smaller ozone "dimple" observed during the Arctic spring over the North Pole. Ozone at middle latitudes has declined, but to a much smaller extent (about 4-5 percent.)
  • If conditions became more severe (cooler stratospheric temperatures, more stratospheric clouds, more active chlorine) then global ozone may decrease at a much greater pace. Standard global warming theory predicts that the stratosphere will cool.
  • When the Antarctic ozone hole does break up, the ozone-depleted air drifts out into nearby areas. Decreases in the ozone level of up to 10% have been reported in New Zealand in the month following the break-up of the Antarctic ozone hole.

Consequences of ozone depletion

Since the ozone layer absorbs ultraviolet light from the Sun, ozone layer depletion is expected to increase surface UV levels, which could lead to damage, including increases in In medicine (dermatology), there are several different types of cancer referred to under the general label of skin cancer. The most common types are squamous cell carcinoma and basal cell carcinoma, while the most dangerous is malignant melanoma. Skin cancer is an increasingly common condition, in part attributed to increased... skin cancer. This was the reason for the Montreal Protocol. Although decreases in stratospheric ozone are well-tied to CFCs, and there are good theoretical reasons to believe that decreases in ozone will lead to increases in surface UV, there is not much direct observational evidence linking ozone depletion to higher incidence of skin cancer in human beings.


Increased UV due to the ozone hole

Ozone, while a minority constituent in the earth's atmosphere, is responsible for most of the main absorption of ultraviolet radiation. The amount of UV radiation that penetrates through the ozone layer decreases The term Categories: Disambiguation | Exponentials ... exponentially with the thickness/density of the layer. Correspondingly, a decrease in atmospheric ozone is expected to give rise to significantly increased levels of UV near the surface.


Increases in surface UV due to the ozone hole can be partially inferred by radiative transfer model calculations, but cannot be calculated from direct measurements because of the lack of reliable historical (pre-ozone-hole) surface UV data, although more recent surface UV observation measurement programmes exist (e.g. at Lauder, New Zealand is a country formed of two major islands and a number of Pacific Ocean. A common Māori name for New Zealand is Aotearoa, popularly translated as Official languages English, Māori, NZSL Capital Wellington Largest city Auckland Government Queen Governor-General Prime Minister... New Zealand [6] (http://www.niwa.co.nz/services/uvozone/)).


Because it is this same UV radiation that creates the ozone in the ozone layer from O2 (regular oxygen) in the first place, a reduction in stratospheric ozone would actually tend to increase photochemical production of ozone at lower levels (in the The troposphere is the lowermost portion of Earths atmosphere and the one in which most weather phenomena occur. The greenhouse effect also occurs in the troposphere. The troposphere starts at the earths surface and extends to an altitude of 16-18 km over tropical regions, decreasing to less... troposphere), although the overall observed trends in total column ozone are still a decrease, largely because ozone produced lower down has a naturally shorter photochemical lifetime, so it is destroyed before the concentrations could reach a level which would compensate for the ozone reduction higher up.


Biological effects of increased UV

The main public concern regarding the ozone hole has been the effects of surface UV on human health. As the ozone hole over Antarctica has in some instances grown so large as to reach southern parts of Australia, officially the Commonwealth of Australia, is the sixth-largest country in the world, the only one to occupy an entire continent, and the largest in the region of Australasia/ Oceania. It also includes a number of secondary islands, the largest of which is Tasmania, an Australian State. Australia is... Australia and New Zealand is a country formed of two major islands and a number of Pacific Ocean. A common Māori name for New Zealand is Aotearoa, popularly translated as Official languages English, Māori, NZSL Capital Wellington Largest city Auckland Government Queen Governor-General Prime Minister... New Zealand, environmentalists have been concerned that the increase in surface UV could be significant.


UVB (the higher energy UV radiation absorbed by ozone) is generally accepted to be a contributory factor to malignant Skin cancer, close-up of level IV melanoma Melanoma is a malignant tumour of melanocytes . Melanocytes predominantly occur in the skin but can be found elsewhere, especially the eye. The vast majority of melanomas originate in the skin. Causes Epidemiologic studies suggest that exposure to ultraviolet radiation is one of... melanoma ( In medicine (dermatology), there are several different types of cancer referred to under the general label of skin cancer. The most common types are squamous cell carcinoma and basal cell carcinoma, while the most dangerous is malignant melanoma. Skin cancer is an increasingly common condition, in part attributed to increased... skin cancer) — for example, one study showed that a 10% increase in UVB radiation was associated with a 19% increase in melanomas for men and 16% for women (Fears et al, Cancer Res. 2002, 62(14):3992-6).


So far, ozone depletion in most locations has been typically a few percent. Were the high levels of depletion seen in the ozone hole ever to be common across the globe, the effects could be substantially more dramatic. For example, recent research [7]  (http://sci.newsfactor.com/perl/story/15776.html) has analyzed a widespread extinction of Photomontage of plankton organisms Plankton is the aggregate community of weakly swimming but mostly drifting small organisms that inhabit the water column of the ocean, seas, and bodies of freshwater. The name comes from the Greek term, —meaning wanderer or drifter. While some forms of plankton can move several... plankton 2 million years ago that coincided with a nearby Remnant of Keplers Supernova, SN 1604. A supernova is a type of stellar explosion which appears to result in the creation of a new star upon the celestial sphere. (Nova is Latin for new). The super prefix distinguishes this from a nova, which also involves a star increasing in... supernova. Researchers speculate that the extinction was caused by a significant weakening of the ozone layer at that time when the radiation from the supernova produced Nitrogen has six different oxides: Nitric oxide (NO) Nitrous oxide (N2O) Nitrogen dioxide (NO2) Dinitrogen trioxide (N2O3) Dinitrogen tetroxide (N2O4) Dinitrogen pentoxide (N2O5) The term nitrogen oxide is imprecise and can be used to refer to any of these or to a mixture of them. A mixture is often formed... nitrogen oxides that In chemistry and biology, catalysis (in Greek meaning the reactants and catalyst are in the same phase. For example acids (H+ ion donors) are common catalysts in many aqueous reactions. In this case both the reactants and the catalysts are in the aqueous phase. In heterogeneous catalysis the catalyst is... catalyzed the destruction of ozone (plankton are particularly susceptible to effects of UV light, and are vitally important to marine food-webs).


An increase of UV radiation would also affect crops. A number of economically important species of plants, such as Species Rice (genus is grown. This can develop elongated stems capable of coping with water depths exceeding 2 meters (6 feet). Rice paddies are an important habitat for birds such as herons and warblers, and a wide range of amphibians and snakes. They perform a useful function in controlling insect... rice, depend on Cyanobacteria (Greek: Stromatolite Forms Cyanobacteria include unicellular, colonial and filamentous forms. Some filaments form differentiated cells that are specialized for nitrogen fixation, called heterocysts, and resting cells called akinetes. Each individual cell typically has a thick, gelatinous cell wall, which has a gram-negative stain. They lack flagella, but may... cyanobacteria residing on their roots for the retention of General Name, Symbol, Number Nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15 (VA), 2 , p Density 1.2506 kg/m3 Hardness NA Appearance colorless Atomic properties Atomic weight 14.0067 amu Atomic radius (calc.) 65 (56) pm Covalent radius 75 pm van der Waals radius 155 pm Electron... nitrogen. Cyanobacteria are very sensitive to UV light and they would be affected by its increase.


Aside from the direct effect of ultraviolet radiation on organisms, increased surface UV leads to increased tropospheric ozone, as noted above. Paradoxically, at ground-level ozone is generally recognised to be a health risk, as ozone is toxic due to its strong The most fundamental reactions in chemistry are the redox processes. The term redox process accounts for all processes in which atoms have their oxidation number changed. This can be a simple redox process, such as the combustion of carbon by oxygen to yield carbon dioxide, it could be the reduction... oxidant properties. At the time, ozone at ground level is produced mainly by the action of UV radiation over combustion gases from vehicle exhausts.


Public policy in response to the ozone hole

Environmentalism is activism aimed at improving the environment, particularly nature. This activism is usually based on the ideology of an environmental movement, and often takes the form of public education programs, advocacy, legislation and treaties. Pollution One concern common to most types of environmentalism is opposing pollution. In this sense... Environmentalists assert that the CFCs have caused so much damage to the ozone layer that CFCs should be completely banned. The full extent of the damage CFCs have caused is not known and will not be known for decades; however, marked decreases in column ozone have already been observed (as explained above).


In 1987 is a common year starting on Thursday of the Gregorian calendar. Events Environmental change Varroa destructor, an invasive parasite is found in the US October 15 - Hurricane force winds cause extensive damage in southern England. January January 1 - Frobisher Bay, Northwest Territories, changes its name to Iqaluit. In 1999... 1987, the The Montreal Protocol on Substances That Deplete the Ozone Layer is an international treaty designed to protect the ozone layer from depletion by phasing out the production of a number of substances believed to be responsible for ozone depletion. The treaty was opened for signature on September 16, 1987 and... Montreal Protocol was signed, controlling the emissions of CFCs. To some extent, their role has been replaced by the less damaging hydro-chloro-fluoro-carbons ( Hydrochlorofluorocarbons (HCFCs) is one of a class of fluorocarbon compounds that are used primarily as chlorofluorocarbon (CFC) substitutes. Work on CFC alternatives began in the late 1970s after the first warnings of CFC damage to stratospheric ozone. By adding hydrogen to the chemical formulation, chemists made CFCs less stable in... HCFCs), although concerns remain regarding HCFCs also.


Pielke and Betsill (http://sciencepolicy.colorado.edu/admin/publication_files/1997.11.pdf) provide an extensive review of early US govt responses to the emerging science of ozone depletion by CFCs.


The future of ozone depletion

Enlarge
Ozone-depleting gas trends

Since the adoption and strengthening of the Montreal Protocol has led to reductions in the emissions of CFCs, atmospheric concentrations of the most significant compounds have been declining. These substances are being gradually removed from the atmosphere. By 2015, the Antarctic ozone hole should have reduced by only 1 million km2 out of 25 (Newman et al, GRL 2004); complete recovery of the Antarctic ozone layer will not occur until the year 2050 or later.


There is a slight caveat to this, however. Global Mean Temperatures 1880-2005 Global warming is a term used to describe an increase over time of the average temperature of Earths atmosphere and oceans. Global warming theories attempt to account for the rise in average global temperatures since the late 19th century (0.6 ± 0.2°C... Global warming from CO2 is expected to cool the stratosphere. This, in turn, would lead to a relative increase in ozone depletion and the frequency of ozone holes. The effect may not be linear: ozone holes form because of polar stratospheric clouds; the formation of polar stratospheric clouds has a temperature threshold above which they will not form; cooling of the Arctic stratosphere might lead to Antarctic-ozone-hole-like conditions. But at the moment this is not clear.


Even though the stratosphere as a whole is cooling, high-latitude areas may become increasingly predisposed to springtime stratospheric warming events as weather patterns change in response to higher Greenhouse gases are gaseous components of the atmosphere that contribute to the greenhouse effect. The major natural greenhouse gases are water vapor, which in the cloudless case causes (see note below) about 60-70% of the greenhouse effect on Earth, carbon dioxide (about 26%) and ozone. [1] Minor greenhouse gases... greenhouse gas loading. This would cause PSCs to disappear earlier in the season, and may explain why Antarctic ozone hole seasons have tended to end somewhat earlier since 2000 - Wikipedia /**/ @import /skins/monobook/IE50Fixes.css; @import /skins/monobook/IE55Fixes.css; @import /skins/monobook/IE60Fixes.css; /**/ 2000 From Wikipedia 2000 is a leap year starting on Saturday of the Gregorian calendar. Popular culture also holds the year 2000 as the first year of the 21st century and the 3rd... 2000 as compared with the most prolonged ozone holes of the Events and trends Technology Explosive growth of the Internet; decrease in the cost of computers and other technology Reduction in size and cost of mobile phones leads to a massive surge in their popularity Year 2000 problem (commonly known as Y2K) Microsoft Windows operating system becomes virtually ubiquitous on IBM... 1990s.


The decrease in ozone-depleting chemicals has also been significantly affected by a decrease in General Name, Symbol, Number bromine, Br, 35 Series halogens Group, Period, Block 17 (VIIA), 4, p Density, Hardness 3119 kg/m3 (300 K), NA Appearance Gas: red-brown solid: metallic luster Atomic properties Atomic weight 79.904 amu Atomic radius (calc.) 115 (94) pm Covalent radius 114 pm van der... bromine-containing chemicals. The data suggest that substantial natural sources exist for atmospheric The chemical compound bromomethane is an organic halogen compound with formula BrCH3. It is a colorless, nonflammable gas with no distinctive smell. It occurs naturally in small amounts in the ocean where it is formed, probably by algae and kelp, but is manufactured for industrial use by reacting methanol with... methyl bromide (CH3Br).[8]  (http://www.wmo.ch/web/arep/reports/ozone_2002/06_chapter1.pdf)


The 2004 is a leap year starting on Thursday of the Gregorian calendar. It was designated the: ) lands on Mars. January 8 - Queen Elizabeth II christens the ) lands on Mars. January 27 - The British government narrowly wins a House of Commons vote on the proposed introduction of tutition top-up fees... 2004 ozone hole ended in November is the eleventh month of the year in the Gregorian Calendar and one of four Gregorian months with the length of 30 days. November begins (astrologically) with the sun in the sign of Scorpio and ends in the sign of Sagittarius. Astronomically speaking, the sun begins in the constellation... November 2004 is a leap year starting on Thursday of the Gregorian calendar. It was designated the: ) lands on Mars. January 8 - Queen Elizabeth II christens the ) lands on Mars. January 27 - The British government narrowly wins a House of Commons vote on the proposed introduction of tutition top-up fees... 2004, daily minimum stratospheric temperatures in the Antarctic lower stratosphere increased to levels that are too warm for the formation of polar stratospheric clouds (PSCs) about 2 to 3 weeks earlier than in most recent years.[9]  (http://www.wmo.ch/web/arep/04/bulletin_7_2004.pdf)


The Arctic winter of 2005 was extremely cold in the stratosphere; PSCs were abundant over many high-latitude areas until dissipated by a big warming event in mid-March. This event may have prevented record-setting ozone depletion over the northern spring of 2005.[10] (http://groups.yahoo.com/group/o3ozone)


Controversy regarding ozone science and policy

Any measures against ozone depletion which have a negative The word Categories: Disambiguation ... economic impact will remain a controversial issue due to the strong economic interests involved, with key questions regarding whether the scientific understanding is strong enough to warrant the proposed countermeasures. In this context, it is worth noting that it is commonly believed that one reason for the relative ease of introduction of the Montreal protocol was the availability of CFC replacements at little extra cost.


The consensus among most atmospheric physicists and chemists is that the scientific understanding has now reached a level where countermeasures to control CFC emissions are justified, although the decision is ultimately one for policy-makers and society.


Some atmospheric scientists (for instance Siegfried Frederick Singer (born September 27, 1924) was an atmospheric physicist. In 1959 he was selected as one of Ten Outstanding Young Men of the Nation, by the U.S. Junior Chamber of Commerce. He was involved in designing on of the first instruments used in a satellite to measure... Fred Singer, founder of The Science & Environmental Policy Project (SEPP) is a non-profit educational group founded by retired atmospheric physicist S. Fred Singer. The chair of SEPPs board of directors is retired university president Frederick Seitz, formerly president of the National Academy of Sciences. The project, based in Fairfax, Virginia, has... SEPP) question or completely deny a link between CFCs and ozone depletion [11] (http://www.sepp.org/ozone/ozonefranklin.html).


It is common to see completely nonsensical arguments put forward to prove that CFCs cannot cause ozone depletion — for example, that they are heavier than air and so cannot reach the stratosphere [12] (http://www.junkscience.com/may99/freon.htm). CFCs are heavier than air, but just like General Name, Symbol, Number argon, Ar, 18 Chemical series noble gases Group, Period, Block 18 (VIIIA), 3, p Density, Hardness 1.784 kg/m3 (273 K), NA Appearance Colorless Atomic properties Atomic weight 39.948 amu Atomic radius (calc.) no data ( 71 pm) Covalent radius 97 pm van der Waals... argon, meaning hidden) was discovered in 1898 by William Ramsay and Morris Travers in residue left from evaporating nearly all components of liquid air. In 1960 an international agreement defined the metre in terms of light emitted from a krypton isotope. This agreement replaced the longstanding standard metre located in Paris... krypton and other heavy gases with a long lifetime they are uniformly distributed throughout the The turbosphere (or homosphere) is that portion of the atmosphere that is sufficiently well-stirred by atmospheric motion that long-lived gases are well-mixed and do not appreciably separate by weight. The turbosphere extends up to about 110 km and includes the troposphere, stratosphere, mesosphere, and lower thermosphere [1... turbosphere and reach the upper atmosphere [13] (http://www.so.wustl.edu/science_outreach/curriculum/ozone/info/stratosphere/myths/heavier.html).


Despite this general consensus, the science behind ozone depletion remains complex, and some who oppose the enforcement of countermeasures point to some of the difficulties experienced in these studies. For example, although increased UVB has been shown to constitute a melanoma risk (see above), it has been difficult for statistical studies to establish a direct link between ozone depletion and increased rates of melanoma. Although melanomas did increase significantly during the period 1970-1990, it is difficult to separate reliably the effect of ozone depletion from the effect of changes in lifestyle factors (e.g. increasing rates of foreign travel).


Related articles

  • Ozone (O3) is an allotrope of oxygen, the molecule consisting of three oxygen atoms instead of the more stable diatomic O2. At standard temperature and pressure ozone is a blue gas. Ozone forms a dark blue liquid, below -112 °C, and a dark blue solid, below -193 °C... ozone
  • The ozone layer is that part of the Earths stratosphere which contains relatively high concentrations of ozone. The total quantity of ozone in the ozone layer is not very large; if just the ozone were compressed to the pressure of the air at sea level, it would be only... ozone layer
  • Ozone-oxygen cycle in the ozone layer. The ozone-oxygen cycle is the process by which ozone is continually regenerated in the Earths stratosphere, all the while converting ultraviolet radiation into heat. The chemistry was worked out by Sidney Chapman in 1930. How ozone is made In the first... ozone-oxygen cycle
  • The Montreal Protocol on Substances That Deplete the Ozone Layer is an international treaty designed to protect the ozone layer from depletion by phasing out the production of a number of substances believed to be responsible for ozone depletion. The treaty was opened for signature on September 16, 1987 and... Montreal Protocol
  • Scientific Assessment of Ozone Depletion is a sequence of reports sponsored by WMO/UNEP. The most recent is the 2002 report. The reports were set up to inform the Montreal Protocol and amendments about ozone depletion. Findings Changes in Ozone-Depleting Compounds In the troposphere observations show that the total... Scientific assessment of ozone depletion
  • CFC molecules CFCs (chlorofluorocarbons) are a family of artificial chemical compounds containing chlorine, fluorine and carbon. They were formerly used widely in industry, for example as refrigerants, propellants and cleaning solvents. Their use has been generally prohibited by the Montreal Protocol, because of fears of their possible destructive effects on... CFC
  • Skin cancer, close-up of level IV melanoma Melanoma is a malignant tumour of melanocytes . Melanocytes predominantly occur in the skin but can be found elsewhere, especially the eye. The vast majority of melanomas originate in the skin. Causes Epidemiologic studies suggest that exposure to ultraviolet radiation is one of... melanoma, In medicine (dermatology), there are several different types of cancer referred to under the general label of skin cancer. The most common types are squamous cell carcinoma and basal cell carcinoma, while the most dangerous is malignant melanoma. Skin cancer is an increasingly common condition, in part attributed to increased... skin cancer
  • Greenhouse gases are gaseous components of the atmosphere that contribute to the greenhouse effect. The major natural greenhouse gases are water vapor, which in the cloudless case causes (see note below) about 60-70% of the greenhouse effect on Earth, carbon dioxide (about 26%) and ozone. [1] Minor greenhouse gases... greenhouse gas
  • Ultraviolet (UV) radiation is electromagnetic radiation of a wavelength shorter than that of the visible region, but longer than that of soft X-rays. It can be subdivided into near UV (380–200 nm wavelength) and extreme or vacuum UV (200–10 nm). When considering the effects of... ultraviolet

External links

  • NOAA Stratospheric Ozone Webpage (http://www.ozonelayer.noaa.gov/)
  • Stratospheric ozone depletion (Antarctic, Arctic, and global) (http://www.al.noaa.gov/WWWHD/Pubdocs/StratO3.html) at The National Oceanic and Atmospheric Administration (NOAA) is an agency of the United States Department of Commerce. NOAA operates a network of weather satellites, the National Weather Service, the National Hurricane Center, and cooperates with the National Ice Center. Mission National Weather Service meteorologists preparing a forecast, early 20th century... NOAA
  • Ozone Depletion And Global Environmental Change (http://www.ciesin.org/TG/OZ/oz-home.html) at Columbia University
  • Scientific Assessment of Ozone Depletion: 1998 (http://www.al.noaa.gov/WWWHD/pubdocs/Assessment98/faq.html) - by The World Meteorological Organization (WMO) is an intergovernmental organization with a membership of 187 Member States and Territories. It originated from the International Meteorological Organization (IMO), which was founded in 1873. Established in 1950, WMO became the specialized agency of the United Nations for meteorology (weather and climate), operational hydrology... WMO, Klaus Töpfer, UNEP Exec. Director Headquartered in Nairobi, Kenya, the UN Environment Programme (UNEP) coordinates United Nations environmental activities, assisting developing countries in implementing environmentally sound policies and to encourage sustainable development through sound environmental practices. It was founded on Its activities cover a wide range of issues, from... UNEP, The National Oceanic and Atmospheric Administration (NOAA) is an agency of the United States Department of Commerce. NOAA operates a network of weather satellites, the National Weather Service, the National Hurricane Center, and cooperates with the National Ice Center. Mission National Weather Service meteorologists preparing a forecast, early 20th century... NOAA
  • Ozone FAQ (http://www.faqs.org/faqs/ozone-depletion/)
  • Methyl Bromide Blues (http://www.greens.org/s-r/32/32-15.html)
  • Five Scientific Questions On The Cfc-Ozone Issue (http://www.sepp.org/ozone/5questions.html) by S. Fred Singer
  • A Critique of the UN Scientific Assessment of Ozone Depletion: 1994 (http://www.sepp.org/ozone/ozassm.html) by S. Fred Singer
  • The Ozone-CFC Debacle: Hasty Action, Shaky Science (http://www.sepp.org/ozone/ozonefranklin.html) by S. Fred Singer
  • The Skeptics vs. the Ozone Hole (http://www.wunderground.com/education/ozone_skeptics.asp)
  • WMO/UNEP Scientific Assessment of Ozone Depletion: 1998 (http://www.al.noaa.gov/WWWHD/Pubdocs/Assessment98.html)
  • The Ozone Tour (http://www.atm.ch.cam.ac.uk/tour/) at the Centre for Atmospheric Science, University of Cambridge
  • The Ozone FAQ (http://www.faqs.org/faqs/ozone-depletion/) - a superb resource (but last updated in 1997)
  • The Politics of Methyl Bromide (http://www.greens.org/s-r/32/32-15.html)
  • Jon Shanklin's Ozone pages (http://www.antarctica.ac.uk/met/jds/ozone/), including a pamphlet (http://www.antarctica.ac.uk/met/jds/ozone/ozpamw7.htm).
  • The Ozone Depletion Story (http://www.nrdc.org/air/pollution/hozone.asp)
  • Ozone Depletion (http://www.ace.mmu.ac.uk/eae/Ozone_Depletion/ozone_depletion.html)
  • Discussion of the ozone layer (http://groups.yahoo.com/group/o3ozone)

  Results from FactBites:
 
The Ozone Hole (553 words)
Ozone depletion begins, and the ozone “hole” appears.
The Antarctic ozone hole was discovered in 1985 by British scientists Joesph Farman, Brian Gardiner, and Jonathan Shanklin of the British Antarctic Survey.
The ozone hole is defined geographically as the area wherein the total ozone amount is less than 220 Dobson Units.
Ozone Depletion FAQ Part III: The Antarctic Ozone Hole (6371 words)
The ozone hole occupies the region of the polar vortex where temperatures are below -80 C and where polar stratospheric clouds are abundant.
The ozone hole is confined to the lower stratosphere.
Depletion of the ozone layer therefore cools the stratosphere, and in this sense the hole is self-stabilizing.
  More results at FactBites »

 
 

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