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Sep 16th is celebrated as World Ozone Day every year since 1994 to commemorate the date of the signing of the Montreal Protocol in 1987.
It has been the most successful global environmental treaty so far and the only United Nations environmental agreement to be ratified by every country in the world.
Treaty has been successful in reducing ozone-depleting substances and reactive chlorine and bromine in the stratosphere. As a result, the ozone layer is showing signs of recovery.
The 2019 ozone hole is indeed the smallest it has been since 1982. But the ozone is also influenced by temperature shifts and dynamics in the atmosphere through climate change.
And in 50 years or so, the stratospheric ozone levels are expected to be back to normal.
However, the final recovery is expected to require several lifetimes.
|Must Read: Ozone depletion and Montreal protocol|
What are the other consequences of the ozone depletion?
First, Ozone depletion affects the climate and changes the spectrum of incoming radiation.
Second, the ozone layer may produce new molecular species that change the radiation-emitting and absorbing properties of the atmosphere. This may cause the formation of more tropospheric ozone, which will not be desirable.
Third, in the absence of the ozone layer, the radiations will directly flow to the earth’s surface and change the vertical distribution of molecules in the troposphere and stratosphere. This will change the rate of vertical circulation.
Source: This post is based on the article “Ozone layer recovery may take several lifetimes. But Montreal Protocol saved the Earth” published in the Down to Earth on 22nd September 2021.