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  PlanetSave 23 May 06
Ozone hole may vanish by 2050
Written by AP

ENN 4 May 06
Ozone Layer Shows Signs of Recovery, Scientists Claim
By Patricia Reaney, Reuters

LONDON: The ozone layer is showing signs of recovering, thanks to a drop in ozone-depleting chemicals, but it is unlikely to stabilise at pre-1980 levels, researchers said on Wednesday.

Depletion of the earth's protective ozone layer is caused by the chemical action of chlorine and bromine released by man-made chlorofluorocarbons (CFCs), which are used in aerosol sprays and cooling equipment.

Ozone-depleting chemicals were banned by the 1987 Montreal Protocol which has now been ratified by 180 nations. "We now have some confidence that the ozone layer is responding to the decreases in chlorine levels in the atmosphere due to the levelling off and decrease of CFCs," said Dr Betsy Weatherhead, of the University of Colorado in Boulder.

"Not only is the ozone layer getting better, we feel it is due to the Montreal Protocol," she added in an interview.

The depletion of the ozone layer, which absorbs most of the harmful effects of the sun's ultraviolet radiation, increases the risk of skin cancer and cataracts in humans and may harm crop yields and sea life.

Despite the signs of recovery, Weatherhead, who reported the findings in the journal Nature, said people should still protect themselves from harmful ultraviolet rays.

Weatherhead and Signe Bech Anderson of the Danish Meteorological Institute in Copenhagen analysed data from satellites and ground stations and information from 14 modelling studies. They found that ozone levels have stabilised or increased slightly in the past 10 years.

But full recovery is still decades away. The researchers said depletion has been most severe at the poles and to a lesser extent at mid-latitudes covering bands of North America, South America and Europe.

Shifting temperatures, greenhouse gases, nitrous oxide (N20) and atmospheric dynamics, which can influence ozone levels, are going to change in the future, they added. "Therefore we really don't think ozone is going to stabilise back to its pre-ozone-depleting-substance levels," Weatherhead said.

Volcanic activity on Earth also has an impact. The 1991 Mount Pinatubo eruption in the Philippines caused ozone levels to backslide for several years, according to the researchers.

PlanetSave 23 May 06
Ozone hole may vanish by 2050
Written by AP

Tokyo - The ozone hole over the Antarctic is likely to begin contracting in the future and may disappear by 2050 because of a reduction in the release of chlorofluorocarbons and other ozone-depleting gases, according to a team of Japanese scientists.

The findings are based on a series of numerical simulations carried out by Eiji Akiyoshi of the National Institute for Environmental Studies, near Tokyo, using projected emissions of chlorofluorocarbons and other gases blamed for the ozone hole.

According to a report posted on Friday on the institute's website, the hole is at its largest now but is likely to gradually start contracting around 2020 and disappear by around 2050.

The team's findings are in line with research by other scientists.

Old fridges, air-conditioners still polluting

Some, however, have suggested the hole won't heal until much later because old refrigerators and air-conditioning systems - many in the United States and Canada - are still releasing ozone-killing chemicals.

Both countries curbed those chemicals in newer products.

Satellites and ground stations have been monitoring the ozone hole over the South Pole since its discovery in the 1980s. Chlorofluorocarbon levels in the earth's atmosphere have been declining since the mid-1990s due to international efforts to reduce emissions.
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