Tropical air thins European ozone layer by 30 pct
Date: 11-Feb-02
Country: UK
Author: Neil Chatterjee
"This is significantly lower than what you normally see," said Neil Harris, an ozone researcher at Cambridge University
"If this increases skin cancer you have to worry about those who are skiing," Harris said.
Ozone coverage, measured in Dobson units, dropped to about 250 units at the end of January, from a normal level of 380-400, research by the German aerospace centre DLR showed.
DLR found streams of low-ozone tropical air pushed up from the equitorial regions and spread over southern Spain, France and Germany, increasing harmful ultraviolet rays (UV) by 20-30 percent, the European Space Agency (ESA) said on its website.
An ozone hole is coverage below 200 Dobson units, with such low densities measured over Europe on 30 November 1999 and 8 November 2001, the ESA said.
"The continual decline in ozone levels due to chemical depletion and the increase in frequency of mini ozone holes over Europe is resulting in an increase in harmful biologically active UV radiation," the DLR's Thilo Erbertseder told the ESA.
Scientists said the the air streams were a natural weather phenomenon and more common in winter, but that man-made climate change might be affecting such patterns. The tropical streams also brought unusually warm weather to central Europe.
"These holes do exist naturally. There is evidence for increasing numbers over time," said Harris. "Is climate change causing weather patterns to change? A link is likely."
Ozone can be depleted by chemicals such as chloroflurocarbons (CFCs), previously used in fridges, as well as crop fumigant methyl bromide, of which around 70,000 tonnes is used each year, mostly in developing countries.
Many scientists say an increase in CO2 gases is affecting climate by creating global warming, leading to increased storms and droughts.
Harris said predicting ozone layer recovery was a large aspect of current climate research.
