SUNS 4294 Monday 5 October 1998
ENVIRONMENT: NEW RECORD IN SIZE OF HOLE IN OZONE LAYER
Geneva, Oct 1 (IPS/Gustavo Capdevila) -- The hole in the ozone layer over the Antarctic reached a record size last month, the World Meteorological Organisation (WMO) reported Thursday.
The hole currently covers a surface area over the South Pole two and a half times the size of Europe.
For a few days last month, the hole extended over northern parts of the Antarctic glacial ocean, at 55 degrees southern latitude, and on two occasions it even spread over the southern cone of South America.
The ozone layer over the Antarctic is depleted by the action of chlorine and bromine released from chemical compounds used by human beings, such as chlorofluorocarbons (CFCs) and halons.
Never before had the statistics shown the hole to be so large in the month of September, Rumen Bojkov, special adviser to the secretary-general of the WMO on environmental issues and ozone, told a media briefing in Geneva Thursday.
Signs of the seriousness of the approaching phenomenon began to be seen early last month, when the hole was found to have extended over a surface area of more than 16 million square kms, said the scientist, the WMO's top adviser on the ozone issue.
In the second half of the month, the hole exceeded 25 million square kms in the day to day measurements, two and a half times the size of Europe, which stretches from the Ural mountains to the Atlantic ocean.
The average size for the second half of September was around 20 million square kms in the past few years, although in 1993 a previous peak of 22 million was recorded.
To illustrate the unprecedented depth of the hole, Bojkov pointed out that over a surface area of more than 10 million square kms, more than 85 percent of the ozone layer was destroyed in the lower stratosphere.
Measurements taken in the second half of September at the Antarctic bases of Marambio, 64 degrees southern latitude, Syowa, 69 degrees, and Neumayer, 70 degrees, showed that the ozone layer was almost completely depleted over those areas.
Bojkov said that last month ozone had been depleted at an unprecedented rate, as shown by the data supplied by the WMO member countries that use the stations and satellites of the global system of ozone observation.
Ideal conditions for the ozone depletion by chemical elements like chlorine and bromine occur in the southern hemisphere springtime, when changes in the narrow stratospheric polar vortex combine with extremely low temperatures in the lower stratosphere (80 degrees below zero) and gases released from aerosols and refrigerators.
Each year the area covered by low total ozone begins to spread in early August, peaking in September, while the lowest ozone values are typically seen in early spring - late September and early October. The ozone hole usually disappears again by early December. Ozone found in
the stratosphere which acts as a protective shield to life on earth by absorbing most of the sun's cancer-causing ultraviolet radiation.
The international community has agreed on measures, established in the Montreal protocol, which set targets for phasing out the use of ozone-depleting chemicals. Scientists at the WMO and the UN Environment Programme (UNEP) predict that the effects of the measures to phase out ozone depleters will not begun to be felt until the middle of next century.