By IANS,
Toronto : A new Canadian study says that cosmic rays, not chlorofluorocarbons (CFCs), are the main cause of the depletion of the ozone layer in the earth’s atmosphere. The study also predicts that the largest ozone hole – larger than the size of the US and Canada combined – will occur over Antarctica in “one or two weeks.”
The ozone layer in the earth’s atmosphere absorbs the sun’s high-frequency ultraviolet rays which are deadly for life on earth and cause diseases such as skin cancer and cataracts.
Qing-Bin Lu, who is a professor of physics and astronomy at the University of Waterloo near here and specialist in the study of ozone depletion, said Tuesday that his study belies the two-decade-old theory that the earth’s ozone layer is depleted by chlorine atoms produced by sunlight-induced destruction of chlorofluorocarbons (CFCs) in the atmosphere.
On the contrary, he said, more and more evidence points to a new theory that the cosmic rays – energy particles that originate in space – play a major role in the destruction of the ozone layer. Lu said data from several sources, including satellites of the National Aeronautics and Space Administration (NASA), confirmed a strong link between cosmic ray intensity and ozone depletion.
He said laboratory measurements also demonstrated a mechanism by which cosmic rays cause drastic reactions of ozone-depleting chlorine inside clouds over the South Pole (Antarctica).
Satellite data from 1980 to 2007, covering two full 11-year solar cycles, also demonstrated a significant link between cosmic rays and ozone depletion, he said.
“This finding, combined with laboratory measurements, provides strong evidence of the role of cosmic-ray driven reactions in causing the ozone hole and resolves the mystery why a large discrepancy between the sunlight-related photochemical model and the observed ozone depletion exists,” said Lu.
Recent experiments by the World Meteorological Organization and the United Nations Environment Programme, which use photochemical models, predict the earth’s ozone hole will increase by one to 2.5 per cent and the Antarctic springtime ozone hole by five to 10 per cent between 2000 and 2020.
In sharp contrast, Lu said, his study predicted the severest ozone loss — resulting in the largest ozone hole — over the South Pole (Antarctica) this month.
He also predicted another large ozone hole around 2019.