Scientists say they have found the first firm signs that the thinning ozone layer over the Antarctic is starting to heal.
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The ozone hole was more than 4m square kilometres smaller in September last year than what it was in the year 2000, researchers say, an area nearly half the size of the US.
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The study, published in the Science journal, suggests more than half the shrinkage in the ozone hole is due to the reduction in atmospheric chlorine coming from CFCs.
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The ozone hole in the Antarctic forms and expands during the southern hemisphere spring, between August and September, because of the high levels of chemically active forms of chlorine and bromine in the stratosphere.
It reached a record size in October last year even though atmospheric chlorine continued to decline.
The researchers say this
seemed to be mainly owing to the eruption of the
Calbuco volcano in Chile. Volcanic sulphate forms tiny particles that are the seeds for polar stratospheric clouds, leading to greater ozone loss.
Some scientists say they are still not sure if the shrinking of the ozone hole revealed in the new paper is entirely owing to less chlorine in the stratosphere.
https://www.ft.com/content/de077cfe-3f81-11e6-9f2c-36b487ebd80a