Wed, Nov 07, 2018 - Page 7 News List

Earth’s protective ozone layer finally healing: UN report

AP, WASHINGTON

Earth’s protective ozone layer is finally healing from damage caused by aerosol sprays and coolants, a new UN report said.

The ozone layer had been thinning since the late 1970s. Scientists raised the alarm and ozone-depleting chemicals were phased out worldwide.

As a result, the upper ozone layer above the Northern Hemisphere should be completely repaired in the 2030s and the gaping Antarctic ozone hole should disappear in the 2060s, according to a study released on Monday at a conference in Quito, Ecuador.

The Southern Hemisphere lags a bit and its ozone layer should be healed by mid-century, it said.

“It’s really good news,” said report cochairman Paul Newman, chief Earth scientist at NASA’s Goddard Space Flight Center. “If ozone-depleting substances had continued to increase, we would have seen huge effects. We stopped that.”

High in the atmosphere, ozone shields Earth from ultraviolet rays that cause skin cancer, crop damage and other problems. Use of manmade chemicals called chlorofluorocarbons (CFCs), which release chlorine and bromine, began eating away at the ozone.

In 1987, countries around the world agreed in the Montreal Protocol to phase out CFCs and businesses came up with replacements for spray cans and other uses.

At its worst in the late 1990s, about 10 percent of the upper ozone layer was depleted, Newman said.

Since 2000, it has increased by about 1 to 3 percent per decade, the report said.

If nothing had been done to stop its thinning, the world would have destroyed two-thirds of its ozone layer by 2065, it said.

However, it is not a complete success yet, said University of Colorado’s Brian Toon, 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 increased yet.

On its own, the ozone hole has slightly shielded Antarctica from the much larger effects of global warming — it has heated up, but not as much as it likely would without ozone depletion, said Ross Salawitch, a University of Maryland atmospheric scientist who coauthored the report.

So a healed ozone layer would worsen manmade climate change there a bit, Newman said.

Scientists do not know how much a healed ozone hole would further warm Antarctica, but they do know the immediate effects of ozone depletion on the world and human health, so “it would be incredibly irresponsible not to do this,” Salawitch said.

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