The ozone layer is beginning to heal.
This was revealed investigators found the first clear evidence that the thinning of the ozone layer over Antarctica began to reverse .
Scientists said that in September 2015, the hole was reduced to approximately 4 million square kilometers in size compared to 2000. One area that resembles the surface of India.
the reason for this improvement in the ozone layer is due to phasing out chemicals that destroy .
The study also sheds new conclusions about how volcanoes collaborated to worsen the problem.
Concern skin cancer
in mid-1980, British scientists first noticed a dramatic thinning of ozone in the stratosphere, about 10 kilometers above Antarctica.
ozone is important because it blocks ultraviolet radiation harmful that comes from S ol.
His absence increases the chances of skin cancer, cataracts and harm to animals and plants.
The causes of the hole
In 1986, the American researcher Susan Solomon showed that ozone was being destroyed by the presence of molecules containing chlorine and bromine are the chlorofluorocarbons (CFCs) .
These gases are found in almost everything. From hairsprays up in coolers of air conditioning units.
The reason why the ozone layer is thinner over Antarctica is extreme cold and large amounts of light. This helped produce what are called polar stratospheric clouds.
In these cold clouds chemistry of chlorine that destroys ozone occurs.
The apparent solution
Thanks to the global ban on the use of CFCs in the Montreal Protocol in 1987, the situation in the Antarctic was slowly improving.
several studies have shown the declining influence of CFCs, but according to the authors of this new study, evidence of the “first signs of healing” and that the ozone layer is of again actively growing.
the Solomon professor and his colleagues conducted detailed measurements of the amount of ozone in the stratosphere between 2000 and 2015.
using data from weather balloons, satellites and model simulations, it was shown that the thinning of the layer had decreased by 4 million square kilometers during the period.
found that more than half of the contraction was due solely to the reduction of chlorine atmospheric .
Normally measurements are made in October when the ozone hole is at its peak.
But the team believed that making observations in September could have a better picture of the situation as temperatures are still low and other factors, excluding the climate, can influence the amount of ozone.
“Although the production of CFCs in all countries, including India and China around 2000, removed there is still a lot of chlorine remaining in the atmosphere ” said professor Solomon the BBC program “Science in Action”.
“it has a lifespan of about 50 to 100 years, so it is beginning to decline slowly and ozone will recover gradually.
“ We do not expect a full recovery until around 2050 or 2060 , but we note that since September the ozone hole is not shown in such bad condition as it used to be” .
Surprise
a finding that puzzled the researchers did they find October 2015 , when the ozone hole set a record in size over Antarctica .
Scientists believe that a key factor by which the hole marked that record was volcanic activity .
” after an eruption, volcanic sulfur form tiny particles and these are the seeds of polar stratospheric clouds, “explained Solomon teacher.
” are created even more of these clouds when you have a recent major volcanic eruption and this leads to further loss of ozone.
“Until we made our recent work, nobody noticed that the eruption of Calbuco volcano in Chile had affected significantly the loss of ozone in October last year “.
the study has been rated as ” historical importance “ by some other researchers in this area.
” This is the first convincing evidence that the cure Antarctic ozone hole has begun, “said Markus Rex, the Alfred Wegener Institute for Polar and Marine Research in Germany.
” at the moment the state of the ozone layer it is still very bad, but I think it is very important to recognize that the Montreal Protocol is working and has an effect on the size of the hole. This is a big step forward “he added.
Different views
But others are not convinced that the decline shown in the new study is due to a reduction in the amount of chlorine in the stratosphere.
“the data clearly show significant variations from year to year and that are much higher than the trends shown in the document,” said Paul Newman of NASA.
“If the study includes last year, which had a hole much more significant ozone, the overall trend would be less”.
Regardless of these questions, the scientists involved in the study believe that history of ozone is a great model about how to address global environmental problems.
“it’s just been remarkable,” said Solomon teacher.
“This was an era in which international cooperation worked pretty well on some issues. I was inspired by how the developed countries and developing countries were able to work together to deal with the ozone hole, “he said.
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