Scientists were bracing for a massive ozone hole to form in Antarctica this fall, as last year’s underwater volcano spewed large amounts of water into the atmosphere. But this did not happen. Instead, this year’s ozone hole was the average size of the past 20 years, even slightly smaller than 2022, according to NASA and the National Oceanic and Atmospheric Administration.

Between September and mid-October, this year’s ozone hole averaged 8.9 million square miles (23.1 million square kilometers); This was the 16th largest hole since satellites began tracking it in 1979. This year it reached 10 million square miles (26 million square kilometers). about the size of North America.

Ozone, with three bonded oxygen atoms, protects the Earth from the sun’s ultraviolet rays, which, when 5 to 30 miles (8 to 50 kilometers) high in the atmosphere, can cause skin cancer, cataracts, and even sterilize crops. Due to chemicals in aerosol sprays and refrigerants that produce ozone-depleting chemicals, Earth’s ozone layer began to thin a few decades ago and even created a large hole over Antarctica in September and October.

“This is a huge scale,” said Paul Newman, chief of NASA’s Ozone Research Division and head of the Earth Sciences Division at Goddard Flight Center. “The situation is very bad for the people who are forced to live in this depleted region” in southern South America.

“But it wasn’t as bad as we thought,” Newman said.

When the Hunga Tonga Hunga Ha’apai volcano spewed millions of tons of water into the southern hemisphere’s atmosphere in January 2022, scientists predicted that 10% more water than normal would eventually be harmful to the ozone layer.

That’s because liquid water in the upper atmosphere makes room for chlorine and bromine to settle and erode the ozone layer, making the annual hole larger, Newman said. That’s why scientists and computer models predicted that the ozone season would be bad this year.

“We were wrong,” Newman said.

Newman said researchers need to figure out where their understanding and computer modeling went wrong. He believes water freezes higher and earlier, leaving fewer clouds and liquid water for ozone-depleting chemicals. Local weather conditions also cause the amount of ozone to fluctuate.

The ozone hole and the thinner ozone layer improved somewhat with the 1987 Montreal Protocol, in which countries around the world agreed to halt production of many ozone-depleting chemicals, Newman said. The ozone hole reached its largest point at about 11.6 million square miles (29.9 million square kilometers) in 2000, according to NASA. But scientists say it will take decades to fully recover. Source