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The ozone layer, which shields life from harmful ultraviolet light, is slowly recovering because countries phased out ozone-destroying chemicals under the 1987 Montreal Protocol.

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ScienceClimate

The story behind the card

Chlorofluorocarbons, or CFCs, were once common in aerosol sprays, fridges, air conditioners and foam. In the 1970s scientists showed that high in the atmosphere they release chlorine, which destroys ozone, and in 1985 British researchers reported a deep seasonal thinning over Antarctica, the 'ozone hole'. The Montreal Protocol, agreed in 1987, set a timetable for phasing these chemicals out, and it became the first treaty in United Nations history to be ratified by every member state. The 2022 scientific assessment carried out under the treaty found the ozone layer on course to return to its 1980 state around 2040 over most of the world, around 2045 over the Arctic and around 2066 over Antarctica.

Türkçe oku
Dünya'daki canlıları zararlı morötesi ışınlardan koruyan ozon tabakası yavaş yavaş iyileşiyor. Bunu, ülkelerin 1987'de imzalanan Montreal Protokolü'yle ozonu yok eden kimyasalları adım adım bırakmasına borçluyuz.

Kloroflorokarbonlar, kısaca CFC'ler, bir zamanlar sprey kutularında, buzdolaplarında, klimalarda ve köpük malzemelerde yaygın biçimde kullanılıyordu. 1970'lerde bilim insanları, bu gazların atmosferin yukarı katmanlarında ozonu yok eden klor açığa çıkardığını gösterdi. 1985'te İngiliz araştırmacılar Antarktika üzerinde her yıl belli bir mevsimde ozonun büyük ölçüde azaldığını, yani “ozon deliğini” duyurdu. 1987'de kabul edilen Montreal Protokolü bu kimyasalların aşama aşama bırakılması için bir takvim belirledi ve Birleşmiş Milletler tarihinde bütün üye devletlerin onayladığı ilk antlaşma oldu. Antlaşma kapsamında hazırlanan 2022 bilimsel değerlendirmesine göre ozon tabakası dünyanın çoğunda 2040 dolaylarında, Kuzey Kutbu üzerinde 2045 dolaylarında, Antarktika üzerinde ise 2066 dolaylarında 1980'deki düzeyine dönecek.

Sources and further reading

Background reading: Montreal Protocol
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