How does ozone depletion occur

Bromine is many times more effective at destroying stratospheric ozone than chlorine. Methyl Bromide is an effective pesticide used to fumigate soil and many agricultural products. Because it contains bromine, it depletes stratospheric ozone and has an ozone depletion potential of 0.

Production of methyl bromide was phased out on December 31, , except for allowable exemptions. In the s, concerns about the effects of ozone-depleting substances ODS ODS A compound that contributes to stratospheric ozone depletion.

Gaseous CFCs can deplete the ozone layer when they slowly rise into the stratosphere, are broken down by strong ultraviolet radiation, release chlorine atoms, and then react with ozone molecules.

See Ozone Depleting Substance. Aerosols are emitted naturally e. There is no connection between particulate aerosols and pressurized products also called aerosols. See below propellants. However, global production of CFCs and other ODS continued to grow rapidly as new uses were found for these chemicals in refrigeration, fire suppression, foam insulation, and other applications.

Some natural processes, such as large volcanic eruptions, can have an indirect effect on ozone levels. For example, Mt. Pinatubo's eruption did not increase stratospheric chlorine concentrations, but it did produce large amounts of tiny particles called aerosols aerosols Small particles or liquid droplets in the atmosphere that can absorb or reflect sunlight depending on their composition.

These aerosols increase chlorine's effectiveness at destroying ozone. The aerosols in the stratosphere create a surface on which CFC-based chlorine can destroy ozone. However, the effect from volcanoes is short-lived. Not all chlorine and bromine sources contribute to ozone layer depletion.

For example, researchers have found that chlorine from swimming pools, industrial plants, sea salt, and volcanoes does not reach the stratosphere. In contrast, ODS are very stable and do not dissolve in rain. Thus, there are no natural processes that remove the ODS from the lower atmosphere.

One example of ozone depletion is the annual ozone "hole" over Antarctica that has occurred during the Antarctic spring since the early s. This is not really a hole through the ozone layer, but rather a large area of the stratosphere with extremely low amounts of ozone. Ozone depletion is not limited to the area over the South Pole. Research has shown that ozone depletion occurs over the latitudes that include North America, Europe, Asia, and much of Africa, Australia, and South America.

More information about the global extent of ozone depletion can be found in the Scientific Assessment of Ozone Depletion: developed by the United Nations Environment Programme. Skip to main content. Climate Ozone Depletion The ozone layer helps to protect life from harmful ultraviolet radiation. Find out what caused the ozone hole, and how the Montreal Protocol sought to put an end to ozone depletion.

Ozone threats and 'the hole' In , Mario Molina and Sherwood Rowland , two chemists at the University of California, Irvine, published an article in Nature detailing threats to the ozone layer from chlorofluorocarbon CFC gases.

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All resources. The ozone hole. Warm up If you were to ask somebody at random about the ozone hole, there is a good chance they will have heard of the problem: but would they be able to explain what it is and why it occurs? Cold facts Measuring stratospheric ozone and the discovery of the ozone hole Ozone is measured as the total amount that is present in a column of overlying atmosphere in Dobson units.

Reasons for the ozone hole The ozone hole has developed because people have polluted the atmosphere with chemicals containing chlorine and bromine. A simplified description of the process involving CFCs is as follows: Once they reach the stratosphere, un-reactive CFCs can be broken down by UV radiation to release reactive chlorine. For this to occur, clouds need to be present in the stratosphere to provide ice crystal surfaces on which these chemical reactions can take place.

ClO quickly breaks down to release the Cl atom which can repeat the process with another O3 molecule. In this way, one chlorine can gobble its way through around molecules of ozone before it leaves the stratosphere. The problem and the solutions The ozone layer protects life from harmful UV-B radiation which can cause cancer and stunt the growth of plants.

Learn more about the Montreal Protocol: Australian Government. United States Environmental Protection Agency. United Nations Development Programme. Student activity 1 Write a summary Use the text above, and information from any of the links listed, to write your own summary of the ozone hole.

As shown in the figure, the increase in carbon dioxide is the major contributor to climate change. Carbon dioxide concentrations are increasing in the atmosphere primarily as the result of the burning of coal, oil, and natural gas for energy and transportation. The relative impacts on climate of various other "greenhouse" gases are also shown on the figure.

There is an additional factor that indirectly links ozone depletion to climate change; namely, many of the same gases that are causing ozone depletion are also contributing to climate change.