2020's hole in the ozone layer closed after reaching a record size

Daniel Martins
·2 min read
2020's hole in the ozone layer closed after reaching a record size
2020's hole in the ozone layer closed after reaching a record size
2020's hole in the ozone layer closed after reaching a record size

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Last year's ozone hole over Antarctica finally sealed itself with just a scant few days left in 2020, after having grown to its largest size on record.

That's according to the World Meteorological Organization (WMO), which says the breach in Earth's natural ozone layer, which protects the planet from ultraviolet (UV) radiation, peaked at 24.8 million square kilometres in late September. It was closed on December 28th.

The WMO says 2020's hole was the largest ever measured – following on the heels of 2019, when it was the smallest it had been since the 1980s.

Ozone hole levels WMO graphic
Ozone hole levels WMO graphic

Image courtesy: WMO/Copernicus/ECMWF

“The last two ozone hole seasons demonstrate the year-to-year variability of the ozone hole and improve our understanding of the factors responsible for its formation, extent and severity,” Oksana Tarasova, head of WMO's Atmospheric Environment Research Division, said in a release from the organization.

The Antarctic ozone hole is a naturally occurring phenomenon, first discovered in 1985, that typically opens up each year from August to December. It can be affected by natural atmospheric events, and also by man-made factors.

In 2020's case, a strong and stable polar vortex kept temperatures at the level of the ozone layer over Antarctica in a state of consistent cold, while preventing ozone-rich air from flowing in to replenish it.

As for human impact, there are a number of chemicals that, once released into the atmosphere, have the effect of depleting the ozone layer. A multinational 1987 agreement, known as the Montreal Protocol, regulates around 100 of these substances. Since then, the ozone layer has gradually recovered, and a 2018 WMO assessment estimated that, at the current pace, Antarctic ozone values will return to pre-1980 levels by mid-century.

“We need continued international action to enforce the Montreal Protocol on ozone-depleting chemicals. There is still enough ozone-depleting substances in the atmosphere to cause ozone depletion on an annual basis,” Tarasova said.