Ozone layer is known to prevent hard life-destructing UV radiation coming from the space from penetrating Earth’s atmosphere. So when in early 80s news about fast depletion of ozone layer and formation of huge ozone holes appeared, the society aroused and started ozone layer conservation movement, which then became one of the most important tasks of World Ecology Movement. Since 1979 general ozone content in the atmosphere have been decreasing at a rate of 2.5% per decade.
 

Russian scientists from Ozone Monitoring Department of Central Aerologic Observatory (city of Dolgoprudniy, Moscow region) Grigori Kruchenitsky and Anatoly Zvyagintsev together with RAS corresponding member Vladimir Zuev (Tomsk RAS SB Institute of Atmospheric Optics) have thoroughly analyzed ozone content data from TOMS modern satellites for the past 20 years. They also used data of world ground ozone network since 1926, where Russian measuring stations are also included. Thanks to statistical technologies the researchers now have clear understanding of how general ozone content over Earth’s surface has been changing in the end of 20th century.
 

The analysis showed that Earth’s ozone layer has improved significantly during recent four years. In the Northern hemisphere its parameters returned to the 70’s level, when ozone layer was considered to be undisturbed. For example, well-known ozone holes over Eastern Siberia have disappeared. Famous Antarctic ozone hole has stopped growing too. Depletion of ozone layer over European Russia has also stopped. It seems interesting that such a fast ozone layer recovery takes place in atmosphere with maximum concentrations of CFCs (chlorofluorocarbons or freons). Let us remind you that the only reason for freons, which are still considered to be main ozone destructors, to enter the atmosphere is human activity. The results allow doubting chemical theory of ozone depletion, which blames freons for that process.
 

On the other hand, general ozone content time behaviour analysis indicates that spatial location of large ozone anomalies abides by certain regularities. For example, there is a high possibility that ozone hole in the Northern hemisphere matches with a zone of high ozone content in the Southern hemisphere. And high latitude (60°– 80°) anomalies are usually observed month or two after anomalies in mid-latitudes (30°–60°) have been detected. These facts prove that flux and reflux of ozone holes can be explained by ozone layer inner dynamics and climate change. But to date it is difficult to study long-term cycles of this process, because serious ozone layer studies have started not long ago – less than 50 years ago. Nevertheless, the scientists have already discovered correlations between ozone layer changes and two-year (with the period of about 28 months) and eleven-year cycles of solar activity and also with so-called North-Atlantic and Southern (El Nino-dependent) Oscillations.
 

The scientists pay attention to the fact that recent ozone layer recovery cannot be explained by the efforts that have been made by world society in order to decrease atmospheric emissions, because this recovery takes place under conditions of maximum CFC concentrations in the atmosphere. Despite all human efforts, CFC concentration is still much higher than in pre-industrial times. This means that we know so little about ozone layer nature and reasons of its changes and cannot make any predictions about its behaviour even for the nearest future. But one thing is absolutely clear – we should develop and upgrade the system for observing this vital Earth shield.