The ozone hole above the Antarctic has begun its annual expansion and will continue to grow significantly over the next four to six weeks, the World Meteorological Organization (WMO) announced on Thursday.
In its latest Ozone Bulletin, the WMO says: 鈥淎s is expected, the annually occurring ozone hole is again forming over Antarctica. The ozone hole is still small but will expand and deepen during the next 4 to 6 weeks.鈥�
The Bulletin goes on to say that the hole above the Antarctic is 鈥渘ormal for this time of year.鈥�
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The ozone hole above the Antarctic appears each year as a result of a chemical reaction triggered by low temperatures.
Skin cancer
The ozone layer stretches from 10 kilometres to 50 kilometres above the Earth鈥檚 surface. The gas provides a protective barrier against certain wavelengths of ultra-violent radiation from the Sun, which can cause skin cancer.
On 13 August, a patch of low ozone concentration was detected near South America. By 16 August, this had covered much of Argentina and ground-based measurements of ozone in Buenos Aires indicate a 20 percent reduction compared to levels measured between 1964-76.
The WMO says this may be partly due to the growing Antarctic hole, but may also be the result of meteorological conditions.
快猫短视频s believe that atmospheric ozone depletion will continue until ozone-destroying chemicals are reduced to pre-1970鈥檚 levels 鈥� estimated to happen in about 2040.
The announcement comes as world leaders meet in Johannesburg, South Africa to discuss environmental issues at the World Summit on Sustainable Development.