The seasonal "ozone hole" over the South Pole has disappeared again
after reaching record size earlier this year, UN officials said
Thursday. The hole is a thinner-than-usual area in the protective layer
of gas high up in the Earth's atmosphere. It has been forming in the
extremely low temperatures that mark the end of Antarctic winter every
year since the mid-1980s, largely due to chemical pollution. This year,
the hole peaked at 28 million square kilometres in mid-September -
matching the record size set three years ago. Scientists have said the
phenomenon results from destruction of the gas in the atmosphere by
chemical compounds, such as chlorofluorocarbons released in some
aerosols and refrigerants. The hole refills with surrounding ozone-rich
air as temperatures rise. In addition to its record size, researchers
said this year's ozone depletion also persisted longer. In October,
researchers said the conditions raised concerns about more harmful UV
radiation reaching Earth. "The ozone hole size and persistence have
developed similarly to the year 2000, with an early rapid growth
observed during August, a record size observed in September and finally
its disappearance in mid-November," said a statement by the World
Meteorological Organization. The use of chlorofluorocarbons has been
curbed under a global accord and levels of the chemicals in the
atmosphere have been declining. But scientists predict it will take
about 50 years for the ozone hole to stop forming. The lack of ozone can
let harmful ultraviolet rays from the sun reach the Earth's surface,
causing skin cancer and cataracts, as well as destroying tiny plants and
organisms at the beginning of the food chain.
Article @
Source: CTV Canada, 21 November 2003
after reaching record size earlier this year, UN officials said
Thursday. The hole is a thinner-than-usual area in the protective layer
of gas high up in the Earth's atmosphere. It has been forming in the
extremely low temperatures that mark the end of Antarctic winter every
year since the mid-1980s, largely due to chemical pollution. This year,
the hole peaked at 28 million square kilometres in mid-September -
matching the record size set three years ago. Scientists have said the
phenomenon results from destruction of the gas in the atmosphere by
chemical compounds, such as chlorofluorocarbons released in some
aerosols and refrigerants. The hole refills with surrounding ozone-rich
air as temperatures rise. In addition to its record size, researchers
said this year's ozone depletion also persisted longer. In October,
researchers said the conditions raised concerns about more harmful UV
radiation reaching Earth. "The ozone hole size and persistence have
developed similarly to the year 2000, with an early rapid growth
observed during August, a record size observed in September and finally
its disappearance in mid-November," said a statement by the World
Meteorological Organization. The use of chlorofluorocarbons has been
curbed under a global accord and levels of the chemicals in the
atmosphere have been declining. But scientists predict it will take
about 50 years for the ozone hole to stop forming. The lack of ozone can
let harmful ultraviolet rays from the sun reach the Earth's surface,
causing skin cancer and cataracts, as well as destroying tiny plants and
organisms at the beginning of the food chain.
Article @
Source: CTV Canada, 21 November 2003



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