It is not yet clear to what extent human activity is destructive for the ozone layer
Everybody knows that the ozone layer is essential for the planet. The natural gas ozone absorbs ultraviolet coming from the Sun and stops it on the way to the Earth. The ozone hole phenomenon was opened by British researchers in 1985. The discovery shocked experts all over the world who immediately warned the ozone hole would be the reason of the end of the world. The biggest ozone hole located over Antarctic was discovered in 1992.
The ozone hole over Antarctic has been decreasing within the past years. Researchers even expected that the ozone layer would be restored in fifty years. Indeed, pictures taken in space and demonstrating the 20 per cent reduction of the ozone hole (from 29 million of square kilometers in 2003 to 24 million in 2004) are impressive indeed.
But in August this year, researchers registered an increase of the ozone hole over Antarctic. Head of St.Petersburg's Rosgidromet laboratory controlling the ozone layer Arkady Shalamyansky told reporters that in August the ozone level is the lowest in that area. And researchers register the biggest size of the ozone hole at this very period. He adds that the hole is highly likely to decrease in the nearest time.
During the cold Antarctic winter (August is cold February in Antarctic) when the temperature in the lower stratosphere drops to 80 centigrade degrees below zero, the cold air goes down and causes polar whirlwind at a height of 10-20 kilometers. As a result of it, stratospheric polar clouds with chlorine compounds on the surface appear. The process continues all the winter long; by the end of winter, the amount of chlorine compounds is rather high in the polar whirlwind. When the Antarctic spring begins at beginning of September, the chlorine compounds dissociate and appear active chlorine particles that break the ozone layer.
It is a proven fact that human activity makes the ozone layer thinner. However disputes concerning the seriousness of the impact are still heated. Arkady Shalamyansky says the anthropogenic factor does affect the ozone layer. The harmless gas Freon also gets accumulated in the atmosphere and affects the ozone layer the same way that chlorine does. "There are various treaties signed by many countries including Russia and prohibiting usage of Freon in production of refrigerators, perfume and other things. But it is not yet clear to what extent human activity is destructive for the ozone layer. Some experts believe that destruction of the ozone layer is a cyclic process and others state it gets broken because of the human activity only," Arkady Shalamyansky says.