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The Ozone Layer Is on Track for a Total Recovery

After a major setback in the 2010s, the most recent U.N. assessment says the Montreal Protocol has succeeded in safeguarding Earth's ozone layer.

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Photo of atmospheric layers
Astronauts on the International Space Station captured this photo of Earth’s atmospheric layers in 2011.
Photo: NASA

When it comes to the health of our environment, it can often feel like everything is falling apart. But a recent assessment from the United Nations environment program offers a rare bit of relief: The ozone layer is on track for a full recovery by 2066. The Montreal Protocol, an international treaty to protect our ozone signed in 1987, has been a success, declared the U.N.-backed scientific panel in a report first released in October 2022 and formally presented on Monday at the American Meteorological Society meeting.

Despite a major setback in the 2010's, the amount of ozone-depleting chemicals emitted worldwide has decreased since 2018. In sum, nearly 99% of those harmful compounds have been phased out since the 1980's, according to a Monday press release. If all continues according to plan, the ozone layer is expected to recover to pre-1980 levels worldwide, including over the Antarctic, by 2066, the assessment says.

After a year of bleak U.N. reports on climate change, the ozone report is “fantastic news,” said U.N. ozone executive secretary, Meg Seki, in the news statement. “Over the last 35 years, the [Montreal] Protocol has become a true champion for the environment,” she added. Through global agreement, scientific assessment, and enforcement, humanity has managed to avert what could’ve become a major planetary crisis.

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The ozone layer is a section of Earth’s upper atmosphere with a high concentration of molecules composed of three oxygen atoms. In the stratosphere, that O3 acts as a critical protective blanket that absorbs some of the sun’s radiation, including cancer-causing UVB light that damages the DNA of all lifeforms. Though the ozone layer goes through natural fluctuations in distribution and thickness, scientists noted the link between certain human-made chemicals and ozone depletion in the 1970s. In the early 1980's, researchers documented a worsening thin-spot, dubbed a “hole,” in the ozone layer over the Antarctic.

Swift and global action to phase out those chemicals followed, and things started to improve. But then, the world began to backslide between 2012 and 2018, and ozone recovery slowed.

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The U.N. conducts its ozone assessments every four years, as part of the Montreal Protocol. The last assessment, published at the end of 2018, noted a disturbing resurgence of a particular ozone-harming emission, known as CFC-11—a banned chemical previously used in refrigerants and insulating foams.

The source of the CFC-11 was initially mysterious, but scientists eventually linked it largely to manufacturing in eastern China. And, as the U.N.’s newest assessment confirms, a national crackdown on CFC-11 production within China seems to have curbed the rise of the illegal chemical emissions. Global annual CFC-11 emissions plummeted from more than 70 gigagrams per year to less than 50 Gg/yr between 2018 and 2021, according to U.N. estimates. Some ongoing CFC emissions are unavoidable, because chemicals already produced and contained within equipment like old fridges, disposed of improperly, inevitably continue to leak out.

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In addition to signaling good news for the safety of our skin and eyes, the U.N. report doubles as good news for climate change. Many of those same ozone-depleting compounds are also hyper-potent greenhouse gases. CFCs, for instance, can cause 10,000 times as much atmospheric warming per pound as carbon dioxide. By reducing CFC and other chemical emissions, the Montreal Protocol has become one of the most effective pieces of global climate policy that we have.

And U.N. leaders also hope it serves as a roadmap for how we could navigate the regulation of other greenhouse gases. “Ozone action sets a precedent for climate action,” said Petteri Taalas, secretary general of the World Meteorological Organization. “Our success in phasing out ozone-eating chemicals shows us what can and must be done – as a matter of urgency – to transition away from fossil fuels, reduce greenhouse gases and so limit temperature increase.”