When countries work together to confront global environmental problems, it actually works. That’s the upshot of the 2018 Scientific Assessment of Ozone Depletion, which found that Earth’s ozone layer has started to recover since humans got serious about preserving it more than 30 years ago.
The Montreal Protocol of 1987 enforced bans and regulations intended to phase out pollutants that break down ozone. Fortunately, those actions decreased harmful materials in the ozone layer and are enabling it to slowly bounce back.
“Outside the polar regions, upper stratospheric ozone has increased by 1 to 3 percent per decade since 2000,” the report concluded.
The report, representing two years of research, was prepared by the World Meteorological Organization, the UN Environment Programme, NASA, NOAA, and the European Commission.
The ozone layer lies roughly six to 30 miles above Earth’s surface, and protects life on our planet from the harmful effects of the Sun’s ultraviolet radiation. During the 1970s, scientists discovered that industrial pollution—especially chlorofluorocarbons (CFCs) found in refrigerants, blowing agents, consumer aerosols, and elsewhere—was depleting it.
While the Montreal Protocol looks to be working over the long term, it’s not all good news: Progress has slowed since 2012 due to a spike in the use of banned chemicals, especially CFC-11.
The report mentions recent claims linking CFC-11 pollution to China’s foam and chemical industries—a 2018 Nature paper measured the new emissions, while an investigation in The New York Times revealed documents suggesting some Chinese factories are ignoring the CFC ban.
Monday’s report emphasized that more research will be needed to track down the sources of the contaminants.
Read More: China’s Construction Industry Is Putting Earth’s Ozone Layer Back At Risk
It also found that the ozone hole above the Arctic Circle had not significantly healed, but the Antarctic hole is on track to be patched by the 2060s.
When scientists modeled what would happen to the holes if ozone-depleting substances had not been phased out, the results showed that “a deep ozone hole could have formed in the Arctic in 2011, and smaller Arctic ozone holes would have become a regular occurrence,” the report said.
In other words, the Montreal Protocol is paying off: Banning ozone-depleting chemicals has successfully stopped these holes from becoming larger and more dangerous. The uptick of new CFC-11 pollutants demonstrates the need for the treaty to be continually enforced, so it can remain a much-needed benchmark of effective international action.
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