Ozone measurements made by ESA's Envisat satellite have revealed the ozone loss of 40 million tons on 2 October 2006 has exceeded the record ozone loss of about 39 million tons for 2000.
Ozone loss is derived by measuring the area and the depth of the ozone hole. The size of this year's ozone hole is 28 million square km, nearly as large as the record ozone hole extension during 2000, and the depth of the ozone hole is around 100 Dobson Units, rivalling the record low ozone values in 1998. This year's record ozone loss was reached because these two measurements occurred during the same time period. (A Dobson unit is a unit of measurement that describes the thickness of the ozone layer in a column directly above the location being measured.)
"Such significant ozone loss requires very low temperatures in the stratosphere combined with sunlight. This year's extreme loss of ozone can be explained by the temperatures above Antarctica reaching the lowest recorded in the area since 1979," ESA Atmospheric Engineer Claus Zehner said. Ozone is a protective layer found about 25 kilometres above us mostly in the stratospheric stratum of the atmosphere that acts as a sunlight filter shielding life on Earth from harmful ultraviolet rays. Over the last decade the ozone level has lowered by about 0,3% per year on a global scale, increasing the risk of skin cancer, cataracts and harm to marine life.
The thinning of the ozone is caused by the presence of pollutants in the atmosphere such as chlorine, originating from man-made pollutants like chlorofluorocarbons (CFCs), which have still not vanished from the air despite being banned under the Montreal Protocol (1987).
During the southern hemisphere winter, the atmospheric mass above the Antarctic continent is kept cut off from exchanges with mid-latitude air by prevailing winds known as the polar vortex. This leads to very low temperatures, and in the cold and continuous darkness of th
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Contact: Mariangela D'Acunto
mariangela.dacunto@esa.int
39-069-418-0856
European Space Agency
2-Oct-2006