GENEVA: The hole in the ozone layer over Antarctica divided in two last week, an unprecedented phenomenon that caught the scientific community by surprise, say officials at the World Meteorological Organisation (WMO).

Michael Proffitt, WMO expert on the Earth’s atmospheric ozone layer, declined to comment on whether he thought the double ozone hole might have positive or negative implications.

“To me it is just a very surprising thing. Scientists did not expect to see this occur,” he said.

Frederic Delsol, director of the WMO atmospheric and environmental programme, related the event to the extremely unusual air currents in the Southern Hemisphere’s atmosphere recorded this year.

The currents have meant that the cyclic formation of the ozone hole has not come about in its normal way and has taken a totally different shape, said Delsol.

The ozone layer, located 15 to 50 km above the Earth’s surface, filters out ultraviolet (UV) radiation that is harmful to all fauna and flora on the planet. Among the public health problems caused by the thinning of the ozone layer are damage to vision and increased incidence of skin cancer.

Since 1980, there has been a cyclical thinning of the ozone layer over Antarctica, usually lasting from August to December. The consequences are the equivalent of a hole measuring millions of square km in area.

The phenomenon is blamed on the emissions of man-made gases, such as chlorofluorocarbons (CFCs) and halons, that break apart the three-oxygen molecule of ozone.

In 1987, 180 countries signed an international agreement, the Montreal Protocol, to eliminate the production and use of those gases by 2010.

The WMO is tracking the evolution of the ozone hole, or holes, through data obtained from the Global Atmosphere Watch Network, with ground stations located around the world, several in Antarctica.

“We also look at satellite images that there are produced almost in real time,” said Proffitt. “We always are very careful to be sure that all sources of data support the same conclusions.”

Two weeks ago, the WMO reported the appearance of one of the smallest holes in the ozone measured in the last decade, but predicted that it would grow wider in the following weeks.

But the Sept 25 observations of the hole caught scientists by surprise. They showed that the hole had divided into two smaller areas, and the centre of each with less than half the density of ozone gas considered normal for the atmospheric layer from January to June.—Dawn/ InterPress News Service