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Topic: Ozone depletion

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Ozone hole

Ozone

Ozone layer

Scientific assessment of ozone depletion

Tropospheric ozone

Ozone therapy

Dobson unit

Stratosphere

CFC

Halon

Ultraviolet radiation

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	Ozone depletion - Wikipedia, the free encyclopedia
		Ozone is formed in the stratosphere when oxygen molecules photodissociate after absorbing an ultraviolet photon whose wavelength is shorter than 240 nm.
		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.
		Because of this uncertainty, it is difficult to estimate the impact of ozone depletion on melanoma incidence.
	en.wikipedia.org /wiki/Ozone_depletion (5967 words)

	Ozone depletion :: Emerging Environmental Issues :: United Nations System-Wide EARTHWATCH
		Major ozone layer losses are now occurring over the northern hemisphere as well, with serious losses since the winter of 1991-92 and a record hole in 1996 lasting two months that doubled carcinogenic ultraviolet rays over an area covering Scandinavia and extending from Greenland to Western Siberia (WMO, 1996).
		Ozone losses in the stratosphere may have caused part of the observed cooling of the lower stratosphere in the polar and upper middle latitudes (about 0.6 degrees centigrade per decade since 1979).
		The increase of ozone in the troposphere since pre-industrial times is estimated to have contributed 10 % to 20 % of the warming due to the increase in long-lived greenhouse gases during the same period.
	earthwatch.unep.net /emergingissues/atmosphere/ozonedepletion.php (1196 words)

	Ozone
		Most of the ozone in the atmosphere exists as a layer in the stratosphere at a height of between 8 and 30 kilometres as shown in the diagram on the main stratospheric page.
		Ozone measurements in the UK are funded by Department for Environment, Food and Rural Affairs (DEFRA) Global Atmosphere Division.
		Record low total ozone amounts were observed over the UK in March 1996 due to both meteorological conditions and the passage overhead of Arctic lower stratospheric air in which ozone had been depleted.
	www.metoffice.com /research/stratosphere/ozone (1260 words)

	Nearctica - Geophysics - Global Change - Ozone Depletion
		Ozone depletion is caused by the release of chlorofluorocarbons (CFCs) and other ozone-depleting substances (ODS), which were used widely as refrigerants, insulating foams, and solvents.
		An introduction to ozone depletion with chapters on the basic science of the atmosphere, the ozone layer, the importance of the ozone layer in filtering out ultraviolet light, and current efforts to curtail the continued degredation of the ozone layer.
		Ozone Action is a non-profit organzation focused exclusively on global climate change and ozone depletion.
	www.nearctica.com /geology/global/ozone.htm (836 words)

	Ozone depletion
		The primary concern regarding ozone depletion is that a decrease in the total column content of ozone leads to an increase in the amount of UV-B radiation reaching the Earth's surface, with adverse effects on human health and ecosystems (Box 1) (UNEP, 1989).
		Stratospheric ozone is also affected by the abundance of carbon dioxide (CO2), because the rates of the chemical reactions that control the abundance of ozone are temperature-dependent, and the abundance of CO2 plays a key role in determining the temperature structure of the stratosphere.
		Models predict that the abundance of ozone: (i) decreases with increasing concentrations of chlorine, bromine and nitrous oxide, and (ii) increases with increasing atmospheric abundances of methane and carbon dioxide.
	www.ciesin.org /docs/011-466/011-466.html (3678 words)

	Ozone Depletion
		Ozone, which has 3 oxygen atoms per molecule rather than the pair of atoms in molecular oxygen, is produced when ultraviolet light interacts with diatomic oxygen.
		The presence of ozone in the upper atmosphere is vital to life on the surface, since it screens out ultraviolet light that could damage animal and plant life.
		Ozone is destroyed by chlorofluorocarbons (CFCs) and other chlorine and bromine compounds (click here for details on the chemical reactions).
	www.suite101.com /article.cfm/chemistry/61014 (512 words)

	Ozone Depletion (Site not responding. Last check: 2007-10-22)
		The ozone layer is located mostly toward the northern and southern parts of the globe, the equatorial parts of the Earth have very little of an ozone layer.
		Depletion is more severe in the winter and spring months as well as in the area of the southern artic region and is caused by some natural processes and many human activities (Fahey 10).
		Ozone depletion is due mainly to the two halogen gases, chlorine and bromine, and also to nitrogen oxides and hydrogen oxides.
	www.personal.psu.edu /students/m/m/mmm5000/ozone_depletion.htm (480 words)

	Global Warming and Ozone Depletion
		The ozone layer is being destroyed by certain industrial chemicals including ozone depleting refrigerants, halons, and methyl bromide, a deadly pesticide used on crops.
		Ozone depletion gets worse when the stratosphere (where the ozone layer is), becomes colder.
		Ozone depletion and global warming have harmful effects on plants and animals.
	www.ess-home.com /news/global-warming/ozone-depletion.asp (1484 words)

	ozone
		Ozone depletion in the upper atmosphere is the result of human-produced chemicals, such as chlorofluorocarbons (CFCs) and halons.
		Depletion is especially severe over Antarctica in spring, causing the highly publicised "ozone hole".
		However, at all latitudes away from the equator, the layer of ozone that protects us from the harmful radiation of the sun is thinner that it was in the late 1970s.
	www.dar.csiro.au /information/ozone.html (337 words)

	Ozone Depletion FAQ Part I: Introduction to the Ozone Layer (Site not responding. Last check: 2007-10-22)
		From: rparson@spot.colorado.edu (Robert Parson) Newsgroups: sci.environment Subject: Ozone Depletion FAQ Part I: Introduction to the Ozone Layer Date: 24 Dec 1997 20:49:01 GMT Message-ID: <67rsft$2ue@peabody.colorado.edu> Reply-To: rparson@spot.colorado.edu Summary: This is the first of four files dealing with stratospheric ozone depletion.
		The present ozone layer is a result of a competition between photolysis and recombination; increasing the recombination rate, by increasing the concentration of catalysts, results in a thinner ozone layer.
		The depletion increases with latitude, and is somewhat larger in the Southern Hemisphere.
	www.faqs.org /faqs/ozone-depletion/intro (8672 words)

	Science - Ozone Depletion
		Stratospheric ozone is threatened by some of the human-made gases that have been released into the atmosphere, including those known as chlorofluorocarbons (CFCs).
		In the process of destroying ozone, the chlorine atoms are regenerated and begin to attack other ozone molecules...
		The chlorine and bromine in human-produced chemicals such as the ones known as chlorofluorocarbons (CFCs) and halons are depleting ozone in the stratosphere.
	www.ozonelayer.noaa.gov /science/o3depletion.htm (322 words)

	Ozone Depletion (Site not responding. Last check: 2007-10-22)
		Ozone is a relatively unstable form of molecular oxygen containing three oxygen atoms produced when upper-atmosphere oxygen molecules are split by ultraviolet light.
		Although the ozone layer is surprisingly thin, it filters out most of the harmful solar ultraviolet radiation that would otherwise reach the earth's surface.
		In the 1987 Montreal Protocol on Substances that Deplete the Ozone Layer, thirty-seven signatory nations agreed to limit their release of chlorofluorocarbons (CFCs) and halons and to halve CFC emissions by the year 2000, with some exceptions given to developing countries.
	www.chem.brown.edu /chem12/Air/upperatmosphere/ozonedepletion/ozone.html (782 words)

	Ozone Depletion
		The discovery of a major stratospheric ozone layer event (the ozone hole) over Antarctica in 1985 fueled interest in ozone depletion as a potential health and ecological threat related to increased solar ultraviolet radiation.
		From this strong complement of ozone-measuring techniques, it has been possible to measure the decline in ozone over the past two decades at mid-latitudes of the northern hemisphere and the tropics and to characterize the dramatic ozone depletion over Antarctica.
		Ozone depletion, through halogen-related chemistry, is facilitated by increased stratospheric particles as provided by stratospheric clouds in the polar regions and globally by volcanic eruptions.
	www.cmdl.noaa.gov /ozone.html (1002 words)

	Climate Prediction Center - Stratosphere: SBUV-2 Total Ozone - Ozone Hole
		The ozone hole is defined geographicaly as the area wherein the total ozone amount is less than 220 Dobson Units.
		This is graphically illustrated in ozone hole area versus Julian day plots for the years: 1979-80, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005.
		The current year's ozone hole plot shows the progression of this year's ozone hole (red line) and is placed in reference with last year's ozone hole conditions (blue line) and conditions over the previous ten years.
	www.cpc.ncep.noaa.gov /products/stratosphere/sbuv2to/ozone_hole.shtml (541 words)

	USATODAY.com (Site not responding. Last check: 2007-10-22)
		All ozone molecules consist of three oxygen atoms, while the molecules of ordinary oxygen - the stuff in the air that all animals need - are made of two oxygen atoms.
		By the way, the ozone hole is not a "hole" in the usual sense; we don't have to worry about things such as the atmosphere leaking away through the "hole," and there is no way to send the Space Shuttle up to patch it in some way.
		Ozone destruction is an example of one of the ways in which humans have affected the Earth's atmosphere, but it is a separate problem from what is often called "global warming," or "the greenhouse effect."
	www.usatoday.com /weather/wozone0.htm (857 words)

	OZONE DEPLETION (Site not responding. Last check: 2007-10-22)
		The effect of ozone depletion on human health has been a major focus of scientists since the concern about the damage to the ozone layer was first given international prominence in 1972.
		Owing to increasing concern over the continuing depletion of the ozone layer and its possible long-term consequences to all forms of life, the "Vienna Convention for the Protection of the Ozone Layer" was adopted by the international community in March 1985.
		The consensus is that depletion of the ozone layer leads to significant increases in ultra-violet-B radiation (UV-B) reaching the Earth's surface.
	www.nalis.gov.tt /Agri/agri_weather_OzoneDepletionHumanHealth.html (709 words)

	ozone depletion (Site not responding. Last check: 2007-10-22)
		Theories for ozone depletion in the stratosphere are based on the ionisation of CFC's and halogenated hydrocarbons to liberate chlorine through the sun's radiation.After several years of measures to restrict their use the ozone continues to be depleted in the stratosphere.
		Leaked hydrogen from industry, which depletes the ozone, is estimated to be in excess of 100,000,000 cubic metres a year from power generation and water treatment plants throughout the world.
		First, there is a need to determine their potential to react with ozone, secondly their capacity to deplete ozone and finally their ability to reach the upper levels of the atmosphere.
	www.ozone-depletion.com (3277 words)

	Ozone Depletion
		Moreover, the so-called "ozone hole" cannot expand outside of Antarctica, because it is confined to that region by unique meteorological conditions.
		Marsha is on the right track in her understanding as to why ozone depletion can't and won't become a global threat.
		Ozone is then rapidly and naturally replenished by solar UV action on oxygen, and the "ozone hole" quickly refills.
	rous.redbarn.org /objectivism/Writing/RobertBidinotto/OzoneDepletion.html (3675 words)

	Atmosphere - Ozone Depletion
		It is important to note that the ozone in the stratosphere is distinct from ground-level ozone.
		Ozone depletion is not an irreversible problem and it appears that the achievements of the Montreal Protocol will result in the eventual recovery of the ozone layer.
		It is believed that without the Protocol, by the year 2050 ozone depletion would have risen to around 50% in the Northern Hemisphere and 70% in the southern mid-latitudes.
	www.environment.sa.gov.au /reporting/atmosphere/ozone.html (2009 words)

	Frequently Asked Questions about Stratospheric Ozone Depletion
		As their eyes are exposed to a lot of UV due to the high reflectivity of snow and a marked enhancement during the ozone hole, investigation into the impact on penguins is desirable.
		If ozone were to be depleted in the tropics, this would constitute a serious danger because of the naturally occurring high levels of UV-B radiation due to the high solar angles and already relatively low normal stratospheric ozone levels.
		While most of the atmospheric ozone resides in the stratosphere, some ozone is also made in the troposphere by the chemical interactions of pollutants such as nitrogen oxides and hydrocarbons.
	www.gcrio.org /ozone/ozoneFAQs.html (2863 words)

	Climate Prediction Center - Stratosphere: Polar Stratosphere and Ozone Depletion (Site not responding. Last check: 2007-10-22)
		ozone hole, the size of the area where air is cold enough to form Polar Stratospheric Clouds (PSCs), and which parts of this cold air are sunlit such that photo-chemical ozone depletion processes can occur.
		By November, the polar vortex begins to weaken and ozone rich air begins to mix with the air in the "ozone hole" region.
		Also, when ozone in the vortex is depleted, it is not replenished with ozone rich air from outside the vortex.
	www.cpc.ncep.noaa.gov /products/stratosphere/polar/polar.shtml (1799 words)

	U.S. EPA: Ozone Depletion Science
		Ozone depletion is the result of a complex set of circumstances and chemistry.
		Volcanoes and the Oceans are Causing Ozone Depletion
		Ozone Images from the Department of Meteorology, University of Reading, UK Features a 90-day archive of the latest images from global, northern hemisphere, and southern hemisphere ozone measurements.
	www.epa.gov /ozone/science (1088 words)

	Ocean Planet:Perils - Ozone Hole
		The ozone "hole" is really a reduction in concentrations of ozone high above the earth in the stratosphere.
		Each spring the amount of ozone in the stratosphere over Antarctica drops by about half, exposing the Southern Ocean to more UV-B radiation §.
		As the Montreal Protocol takes effect, alternatives less harmful to ozone, such as HFCs (hydrofluorocarbons), are replacing CFCs as coolants in automobiles and other products.
	seawifs.gsfc.nasa.gov /OCEAN_PLANET/HTML/peril_ozone_depletion.html (380 words)

	UNDP/GEF
		The reduction of ozone depleting substances (ODS) is clearly related to the climate change focal area.
		Ozone depletion, then, generally appears as a component of UNDP-GEF climate change projects.
		Guidance for the ozone depletion focal area comes from the United Nations Secretariat of the Multilateral Fund for the Implementation of the Montreal Protocol.
	www.undp.org /gef/undp-gef_focal_areas_of_action/sub_ozone_depletion.html (116 words)

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