WASHINGTON (Reuters) – Earth's protective ozone layer is finally healing from aerosol and soft drink damage, according to a new UN report.
The ozone layer has been dwindling since the late 1970s. Scientists have raised the alarm, and ozone-depleting chemicals have been eliminated all over the world.
As a result, the upper ozone layer above the northern hemisphere should be completely repaired by the 2030s and the ozone hole in the Antarctic should disappear by the 2060s, according to a scientific assessment released Monday at a conference in Quito, Ecuador. The southern hemisphere is a little late and its ozone layer must be cured by the middle of the century.
"This is good news," said report co-chair Paul Newman, the Earth's chief scientist at NASA's Goddard Space Flight Center. "If substances that deplete the ozone layer continue to increase, we would have seen great effects. We stopped that.
High in the atmosphere, ozone protects Earth from ultraviolet rays that cause skin cancer, crop damage, and other problems. The use of man-made chemicals, called chlorofluorocarbons (CFCs), which release chlorine and bromine, began to consume ozone. In 1987, countries around the world agreed in the Montreal Protocol to phase out CFCs, and companies created substitutes for spray cans and other uses.
At worst, by the 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, according to the report.
This year, the ozone hole over the South Pole reached almost 9.6 million square miles. That's about 16% smaller 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 next spring in the southern hemisphere, Newman said.
The ozone layer begins about 6 miles above the Earth and stretches for nearly 25 miles; Ozone is a colorless combination of three oxygen atoms.
If nothing had been done to stop thinning, the world would have destroyed two-thirds of its ozone layer by 2065, Newman said.
But it is still not a complete success, said Brian Toon of the University of Colorado, who was not part of the report.
"We are only at a point where recovery may have started," Toon said, pointing to some ozone measurements that have not yet risen.
Another problem is that the new technology found an increase in emissions from a banned CFC from East Asia, the report noted.
By itself, the ozone hole has protected Antarctica from the much greater effects of global warming – it has warmed, but not as likely without ozone depletion, said Ross Salawitch, a University of Maryland scientist, co-author of search. the report.
Thus, a cured ozone layer will worsen man-made climate change a bit, Newman said.
Scientists do not know how much a cured ozone hole will warm Antarctica even more, but they know the immediate effects of ozone depletion on the world and human health, so "it would be incredibly irresponsible not to do that," Salawitch said.
And the replacements now used to cool cars and refrigerators need to be replaced with chemicals that do not worsen global warming, Newman said. An amendment to the Montreal Protocol, which will come into force next year, would reduce the use of some of these gases.
"I do not think we can make a comeback from the victory until 2060," Newman said. "This will be for our grandchildren to do."