Largest-Ever Hole in Ozone Layer Above North Pole Closes After Being Discovered in 2020

(Illustration - Andrey Armyagov/Shutterstock)

The largest hole in the ozone layer ever recorded, which appeared earlier this year above the North Pole, has recently closed.

Contrary to speculation, scientists are attributing its disappearance to unexpectedly warm spring temperatures, and not to environmental changes owing to the global pandemic.

The hole, covering an area around three times the size of Greenland, was first noticed in February 2020. It reached its largest recorded size in March and was declared closed on April 23, 2020. Copernicus’ Atmospheric Monitoring Service (CAMS) took to Twitter to break the news, citing that a polar vortex split allowed ozone-rich air into the Arctic region, thus shoring up the opening.

Prior to this hole, the largest ozone breach ever recorded occurred in the winter of 2011.

“It is very unusual for such strong ozone depletion to occur in the northern hemisphere,” CAMS’s Antje Inness told Euro News, “but this year’s polar vortex was exceptionally strong and persistent, and temperatures were low enough to allow stratospheric cloud formation for several months.”

In response to the speculation that the hole depleted so rapidly because of reduced air pollution, CAMS responded on Twitter:

“COVID-19 and the associated lockdowns probably had nothing to do with this. It’s been driven by an unusually strong and long-lived polar vortex, and isn’t related to air quality changes.”

The Arctic ozone hole, which opened 11 miles above the surface of the earth, occurred as a result of an extremely cold polar vortex, where high-altitude currents generated stratospheric clouds that reacted with human-made chlorofluorocarbons (CFCs) depleting the ozone layer at an accelerated rate.

Data from NASA indicates that ozone levels above the Arctic reached a record low in March 2020, coinciding with the hole’s largest recorded size. Just as the hole formed rapidly due to unusually cold temperatures, CAMS stated that its disappearance is likely due to the warming and splitting of the polar vortex.

The largest and longest-lasting hole in the ozone layer appears between July and September above the South Pole, where the stratosphere is much colder than in the north. However, the strong and stable 2020 polar vortex in the north caused a greater concentration of ozone-depleting chemicals.

The ozone layer lies between 9 and 22 miles above the surface of the earth and protects life from UV rays emitted by the sun. For humans, a depleted ozone layer means an increased risk of contracting skin cancer and cataracts.

The 1987 Montreal Protocol, signed by 197 countries, pledged to phase out chemicals such as CFCs in an effort to protect the ozone from further damage. The hole over the South Pole has been in gradual decline ever since.

“We don’t know what caused the wave dynamics to be weak this year,” Paul Newman, chief scientist for Earth Sciences at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said in a press release.

“But we do know that if we hadn’t stopped putting chlorofluorocarbons into the atmosphere because of the Montreal Protocol,” he continued, “the Arctic depletion this year would have been much worse.”

The recent closure of the North Pole’s largest ozone layer hole is offering hope and prompting further research.

“We do not know at the moment why the dynamics were so unusual this winter,” Inness from CAMS explained, speaking to Euro News. “I am sure that many scientists will do modeling studies to find out the reasons for this.”