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Researchers have found the first clear evidence that the hole in the ozone layer above Antarctica is starting to heal.

The scientists said that in September 2015 the hole was around 4 million sq km smaller than it was in the year 2000 – an area roughly the size of India.

The improvement has been credited to The Montreal Protocol, an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion such as chlorofluorocarbons (CFCs).

The natural production and destruction of ozone in the stratosphere balances itself out over a long time, meaning that historically there has been a constant level to protect the Earth by blocking out harmful ultraviolet radiation from the Sun.

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Its absence increases the chances of skin cancer, cataract damage, and harm to humans, animals, and plants.

British scientists first noticed a dramatic thinning of ozone in the stratosphere some 10 kilometres above Antarctica in the mid-1980s.

In 1986, US researcher Susan Solomon showed that ozone was being destroyed by the presence of molecules containing chlorine and bromine that came from chlorofluorocarbons (CFCs). These gases were found in everything from hairsprays to refrigerators to air conditioning units.

The reason the thinning was occurring mainly over Antarctica was because of the extreme cold and large amounts of light. These produced what are termed Polar Stratospheric Clouds.

It is also important to note that volcanic activity can spur greater ozone depletion.

 

Source : Science.

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