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Monday, 28 April 2008 |
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First article in a series of two on the Montreal Protocol on ozone and stratospheric
Washington - Since the signing on September 16, 1987, by representatives of 24 countries of the Montreal Protocol on Substances that Deplete the Ozone Layer, this agreement helps reduce more and more production than a hundred substances that destroy ozone in the stratosphere and limiting employment.
Ratified by 191 countries, it has reduced considerably the production of these substances, which rose from 1.8 million tons in 1987 to 83,000 tons at the end of 2008.Because of the widespread application of the Protocol and the development of substitutes less harmful, the ozone layer, which protects our planet in the stratosphere against ultraviolet rays of the sun, has not declined since 1998 to Above the greater part of the earth. It is anticipated that it could become as dense as before 1980 to a date between 2050 and 2075.This recovery, particularly in regard to the hole in the ozone, which occurs in spring over Antarctica, depends on the continued application of the protocol and also, according to scientists, effects of climate change.
According to the deputy director of the National Center for Atmospheric Research of the USA, which reports to the Systems Laboratory Earth and solar, it was not so matter of fact when climate forecasts about the hole in the ozone layer."Now, he said, we know that while the climate is changing, there is a change in temperature in the stratosphere, which has a cooling effect while the surface warms. The water content of the stratosphere could change. Hence, the link between the problem relating to ozone and the problem on the climate becomes important and could accelerate or delay recovery of the ozone layer.
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Last Updated ( Thursday, 03 July 2008 )
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Monday, 28 April 2008 |
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Discoverers
Leon TEISSENREC BORT of highlights in 1902 the role of the ozone layer that absorbs solar radiation (UV actually).
In 1974 two American scientists: Mario Molina and F. SHERWOOD ROWLAND made for the first time the theory of depletion of the ozone layer under the impact of Chlorofluorocarbons (CFCs), appeared in 1938. And J. FARMAN British Antarctica Survey (BAS) announced in 1985 that a "hole" temporary but important (up 50% loss) appears each spring in the ozone layer over Antarctica since 1979 and resolves to early fall.
Evolution of the hole in the ozone layer
What is ozone?
The ozone (O3) is a specific chemical form of oxygen, very unstable and reactive.
Ozone is generated by including the bombing of the oxygen molecule stable O2 by utraviolets (UV). Condition critical: the presence of oxygen that was produced in large quantities with the proliferation of photosynthetic micro-organisms in the Precambrian.
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Last Updated ( Thursday, 03 July 2008 )
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Monday, 28 April 2008 |
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In the 1970's, scientists discovered that CFCs contribute to the depletion of the ozone layer. Since signing the Montreal Protocol in 1987, production and consumption of substances responsible for this loss decreased significantly. It will, however, expected between 2060 and 2075 so that the thickness of the ozone layer back to its level before 1980.Despite a massive reduction, thanks to the Montreal Protocol, production and consumption of chlorofluorocarbons (CFCs) and other harmful substances, the size of the "hole" in the annual ozone layer over the Antarctica remains important.
The lifetime in the atmosphere of different types of CFCs varies from 45 to 1,700 years, according to a report released in February and written by scientists on behalf of the World Meteorological Organization, the UN Programme for the Environment Programme (UNEP) and other agencies.
"It will have to wait long for the concentration of CFCs in the atmosphere is reduced. We still need to wait for a good fifty years before seeing the direct effect of the Montreal Protocol. Today, we are seeing a slowdown in the formation of ozone "hole", which seems to have reached its maximum size, but there are still shrinking, he adds.
In 1928, scientists are developing the first CFCs. In the years 1960, their consumption is increasing rapidly in industrialized countries. CFCs are used as refrigerants, cleaning solvents, aerosol propellants and blowing agents for the manufacture of foams.In 1974, two chemists, Sherwood Rowland and Mario Molina, publish an article in the journal Nature stating that CFCs can destroy ozone in the upper atmosphere, the stratosphere. |
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Last Updated ( Thursday, 03 July 2008 )
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Monday, 28 April 2008 |
 While all media preoccupant of stratospheric ozone hole in Antarctica who just beat all records, is that the stratospheric ozone of the Arctic bears do not really better.Experience on atmospheric chemistry (ACE) conducted aboard the new Canadian scientific satellite SCISAT take measurements of the ozone layer in Canada, particularly in the Arctic. Scientists are concerned about ozone depletion in the Canadian Arctic where large losses of about 45% were observed at the end of 90 years.
A report published recently by Environment Canada and reports of recent findings Canadian scientists showed that the phenomena of ozone depletion in the Arctic could worsen during the next ten to twenty years despite the measures taken to Internationally to reduce the quantities of chemicals that destroy ozone.
Losses increasingly important ozone in the Arctic could be damaging to the fragile Northern agencies. They could also lead to a thinning of the ozone layer above the southern part of Canada as ozone is redistributed in order to offset losses in the Far North.During the next ten to twenty years, the phenomena of impoverishment may even become as frequent and as serious as in Antarctica.
Other recent results
The ozone depletion continues above the rest of Canada where values have decreased by about 6% on average since the end of 70 years, with greater losses of about 8 to 10% spring.The new satellite will help Canadian scientist to take measurements of the ozone layer from space.Because of the depletion of the ozone layer, UV to the origin of sunburn increased by 7% on average in Canada, with peaks reaching between 10 and 12% in the spring. These increased levels, which should remain higher than normal during the next thirty to forty years, will have repercussions on the health of human beings, crops, forests and marine ecosystems and freshwater.
Verification of measures taken by the satellite in the Arctic.
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Last Updated ( Thursday, 03 July 2008 )
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Monday, 28 April 2008 |
 A scientist EC record meteorological data station Alert located on the north-east of Ellesmere Island, T. NW
Climate change may increase the frequency and severity of the loss of stratospheric ozone in the Arctic and could delay the recovery of the ozone layer in the Arctic a decade or more, according to a report from Environment Canada which reviews recent scientific activities on the issue. The results show that greenhouse gas that warms the lower atmosphere are the cause of a cooling in the stratosphere of the Arctic spring, where the contribution of the formation of polar stratospheric clouds that allow the depleting substances ozone layer causing more damage.
Two factors contribute significantly to ozone destruction in polar regions during the spring. One of these factors based on the polar vortex, circulation system in the middle almost closed that isolates the polar stratosphere sunlight and the atmosphere surrounding, where a cooling of the extreme temperature. At temperatures of -80 degrees Celsius or less, we must consider a second factor, or the formation of polar stratospheric clouds. These clouds frozen breed division of ozone-depleting substances, which are usually stable and, therefore, harmless to the ozone layer, volatile compounds that are easily broken by solar radiation. For the return of sunlight in spring, these compounds unstable release large quantities of chlorine and bromine - catalysts powerful ozone-depleting and each molecule can destroy thousands of ozone molecules before returning to the troposphere and the be processed by other chemical reactions.
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Last Updated ( Thursday, 03 July 2008 )
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Stratospheric Ozone Depletion 
