Earth's smallest ozone hole in 5 years closed this month
The hole in the ozone layer over Antarctica only grew to 22 million square kilometres this year, the smallest observed since 2019
The annual hole in Earth's ozone layer closed at the beginning of this month, scientists recently announced. This year's hole in the layer was smaller in 2024 than we’ve seen in any other year this decade.
Experts with the Copernicus Atmosphere Monitoring Service (CAMS) reported that this year’s ozone hole over Antarctica grew to 22 million square kilometres at its maximum extent before closing in early December, putting it in line with the average measured between 1979 and 2021.
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Ozone is helpful high in the atmosphere
This year’s ozone hole began forming in July, reaching its maximum extent of about 22 million square kilometres on Sept. 28 before finally closing in early December.
Scientists use Dobson Units to measure the extent of ozone in the upper atmosphere. Values lower than 220 Dobson Units are considered significantly lower than normal, constituting the 'hole' in the layer. The greatest ozone depletion on record occurred in 1994, when the hole in the layer dropped all the way to 73 Dobson Units.
The maximum annual extent of the ozone layer hole in 2024 was smaller than the maximum extent measured every year since 2019.
Last year’s hole in the ozone layer grew more than 2.5 times larger than Canada itself, expanding to more than 25 million square kilometres in size.
Part of the larger-than-normal disruption in 2022 and 2023 was likely in part due to the Hunga Tonga-Hunga Ha'apai volcanic eruption in January 2022.
Ozone is recovering from 20th century damage
A ‘hole’ in the ozone layer isn’t a literal ozone-less void, but rather a region of significantly less ozone than normal.
Colder temperatures, diminished sunlight, and weather patterns over the Antarctic force Earth’s ozone layer to experience significant depletion during the southern hemisphere’s winter and spring seasons.
Ozone is a molecule made up of three oxygen atoms. While ozone is harmful to humans and animals at high concentrations, it’s a vital gas in Earth’s upper atmosphere.
A layer of ozone in the stratosphere roughly 20 to 40 km above the surface helps to deflect and absorb harmful ultraviolet rays before they can reach the ground.
Ozone concentration in the southern hemisphere on Sept. 28, 2024. Blues and purples indicate lower concentrations of ozone. (Image courtesy of NASA Ozone Watch)
The use of harmful chemicals like chlorofluorocarbons (CFCs) began significantly eroding the ozone layer by the middle of the 20th century.
A worldwide effort to curb the use of these dangerous chemicals, led by the 1987 Montreal Protocol, has allowed the ozone layer to begin recovering. Experts estimate that complete ozone layer recovery is possible by the 2060s.
Despite these improvements, the concentration of ozone over Antarctica continues to experience significant minimums every year.
