Ozone depletion

Ozone depletion refers to the phenomenon of reductions in the amount of ozone in the stratosphere. There was a reduction of approximately 5% detected from 1979 to 1990. Since the ozone layer prevents most harmful wavelengths of ultraviolet light from passing through the Earth's atmosphere, observed and projected decreases in ozone have generated worldwide concern and led to adoption of the Montreal Protocol banning the use of chlorofluorocarbon (CFC) compounds, as well as other ozone depleting chemicals such as carbon tetrachloride, trichloroethane (also known as methyl chloroform), and bromine compounds known as halons.

Related Topics:
Ozone - Stratosphere - 1979 - 1990 - Ozone layer - Ultraviolet - Earth's atmosphere - Montreal Protocol - CFC - Carbon tetrachloride - Trichloroethane - Halon

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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 Antarctica and 30% over the 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.

Related Topics:
Antarctica - Arctic

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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.

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It is suspected that a variety of biological consequences, including, for example, increases in melanoma and the destruction of plankton populations in the ocean's photic zone, may result from the increased UV exposure due to ozone depletion.

Related Topics:
Melanoma - Plankton - Photic zone

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