WASHINGTON (AP) – Earth's protective ozone layer ultimately cures damage caused by aerosol and refrigerants, according to a new UN report.
The ozone layer has been declining since the late 70s. Scientists have raised the alarm and the chemicals that have exhausted ozone have been eliminated worldwide.
As a result, the upper ozone layer on the northern hemisphere should be completely repaired in the 2030s and the Antarctic depleting ozone egg should disappear in the 2060s, according to a scientific assessment published on Monday at a conference in Quito, Ecuador. The southern hemisphere loses a bit and its ozone layer must be cured until the middle of the century.
"It's good news," said co-chairman Paul Newman, Earth's chief scientist at the NASA's Goddard Space Flight Center. "If ozone depleting substances continue to increase, we would have huge effects. We've detected it."
High in the atmosphere, Earth's ozone shields against ultraviolet rays that cause skin cancer, damage to cultures and other problems. The use of artificial chemicals called chlorofluorocarbons (CFCs), which release chlorine and bromine, began to move away from ozone. In 1987, countries around the world agreed to the Montreal Protocol to gradually eliminate CFCs and companies produced replacements for spray cans and other uses.
In its worst situation at the end of 1990, about 10 percent of the upper ozone layer was exhausted, Newman said. Since the year 2000, it has increased by about 1 to 3 percent per decade, according to the report.
This year, the ozone hole on the South Pole reached its peak at 9.6 million square kilometers (24.8 million square kilometers). This is approximately 16 percent less than the largest recorded hole, a total of 11.4 million square kilometers (29.6 million square kilometers) in 2006.
The hole reaches its peak in September and October and disappears in the end of December until the next spring of the Southern Hemisphere, Newman said.
The ozone layer begins about 6 miles (10 kilometers) above the Earth and extends for almost 25 kilometers (40 kilometers); Ozone is a colorless combination of three oxygen atoms.
If nothing was done to stop the slimming, the world would destroy two thirds of the ozone layer before 2065, Newman said.
But it is still not a complete success, said Brian Toon, from the University of Colorado, who was not part of the report.
"We are only at a point where recovery can begin," said Toon, pointing to some ozone measures that have not yet risen.
Another problem is that the new technology found an increase in emissions of a prohibited CFC outside East Asia, the report reported.
By itself, the ozone hole has a bit of protection against Antarctica due to the much larger effects of global warming, which was heated but not as much as probably without ozone, said Ross Salawitch, an atmospheric scientist at the University of Maryland who was co-author or report.
Thus, a healed ozone layer will worsen man-made climate change a bit, Newman said.
Scientists do not know what a cured ozone hole will improve in Antarctica, but they know the immediate effects of ozone depletion in the world and human health, so "it would be incredible irresponsible not to do it," Salawitch said.
And the replacements that are now used to cool cars and refrigerators need to be replaced by chemicals that do not worsen global warming, Newman said. An amendment to the Montreal Protocol that will come into force next year will cut the use of some of these gases.
"I do not think we can make a win win until 2060," said Newman. "This will be for our grandchildren to do."
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