WASHINGTON – The earth's protective ozone layer eventually heals from damage caused by aerosol sprays and refrigerants, according to a new United Nations report.
The ozone layer had become thinner since the late 1970s. Scientists have raised the alarm and ozone-depleting chemicals have been abolished worldwide.
Therefore, the upper ozone layer over the northern hemisphere should be completely repaired in the 2030s, and the gaping ozone hole of the Antarctic should disappear in the 2060s. A scientific assessment was published on Monday at a conference in Quito (Ecuador). The southern hemisphere has lagged slightly and its ozone layer should be healed by the middle of the century.
"It's really good news," said Paul Newman, co-chair of the report, the senior Earth scientist at NASA's Goddard Space Flight Center. "If ozone depleting substances had continued to increase, we would have seen tremendous effects. We stopped it. "
Ozone protects the earth high in the atmosphere from ultraviolet rays that cause skin cancer, crop damage and other problems. The use of artificial chemicals, the so-called chlorofluorocarbons (CFCs), which release chlorine and bromine, began to dissolve in ozone. In 1
At the worst end of the 1990s, about 10 percent of the upper ozone layer was depleted, Newman said. Since 2000, it has risen by about 1 to 3 percent per decade.
This year, the ozone hole at the South Pole reached nearly 9.6 million square kilometers. This is about 16 percent less than the largest recorded hole – 11.4 million square miles in 2006.
The hole peaks in September and October and disappears in late December until the next spring of the Southern Hemisphere, Newman said.
The Ozone The layer begins about 6 miles above the earth and stretches for almost 25 miles. Ozone is a colorless combination of three oxygen atoms.
If nothing had stopped the thinning out, the world would have destroyed two thirds of its ozone layer by 2065, Newman said.
But it's not a full story story yet, said Brian Toon of the University of Colorado, who was not part of the report.
"We're only at a point where recovery could have started," Toon said, pointing to some ozone measurements that have not risen
Another problem is that the new technology will increase emissions banned CFCs from East Asia.
The ozone hole alone has easily shielded the Antarctic from the much larger effects of the world warming – it has heated up, but not as strong as it would without ozone depletion, said Ross Salawitch, an atmospheric scientist at the University of Maryland wrote the report.
A healed ozone layer will thus worsen man-made climate change somewhat, Newman said.
Scientists do not know how much a healed ozone hole will keep the Antarctic warming up.
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