The hole that emerges in Earth's ozone layer annually is unusually large this year, encompassing an area larger than Antarctica, according to the Copernicus Atmosphere Monitoring Service (CAMS).
Using satellite and in situ observations, researchers at CAMS have found that the hole in the ozone layer above the South Pole has considerably grown in the last fortnight after a sluggish start to the season and is now larger than 75 percent of ozone holes at this time of the year since 1979.
The ozone layer is a region of the stratosphere between 15 and 30 kilometers (9.3 to 18.6 miles) above Earth's surface that has a high concentration of the gas ozone compared to other parts of the atmosphere. The layer absorbs much of the Sun's harmful ultraviolet rays, acting as an invisible shield for our planet. This layer is degraded by chlorofluorocarbons (CFCs) — human-made chemicals once widely used in aerosol sprays, solvents, and as refrigerants — after they are wafted up into the stratosphere. Due to their ozone-depleting potential, the manufacture of such compounds has been phased out under the Montreal Protocol (a bit more on that later).
Holes in the ozone might conjure up thoughts of environmental doom, but the hole is not necessarily a symptom of our planet’s plight. The ozone hole, found above the South Pole, naturally fluctuates in size with the season. Each year around September, as the Southern Hemisphere slips into spring, CFCs break down ozone over the Antarctic, causing the ozone layer to break down and thin.
Last year's ozone hole was another big one, primarily due to a strong cold polar vortex that kept Earth's stratosphere extremely chilly. It’s not clear why exactly this year’s hole is so large, but researchers suggest the hole is following a similar pattern to 2020.
“This year, the ozone hole developed as expected at the start of the season. It seems pretty similar to last year's, which also wasn't really exceptional until early September, but then turned into one of the largest and longest-lasting ozone holes in our data record later in the season,” Vincent-Henri Peuch, Director of the CAMS, said in a statement. “Now our forecasts show that this year´s hole has evolved into a rather larger than usual one. The vortex is quite stable and the stratospheric temperatures are even lower than last year, so it may continue to grow slightly over the next two or three weeks.”
Having said the hole in the ozone is not necessarily a sign of environmental decay, it certainly was in previous decades. Throughout the 1970s and 80s, scientists discovered a hole in the ozone layer above the South Pole and it became increasingly apparent it was growing due to the use of CFCs.
In a rare moment of collective global action, the problem was swiftly addressed. The Montreal Protocol, finalized in 1987, saw a global agreement to protect the ozone layer through the phase-out of ozone-depleting substances. To date, the agreement is the only UN treaty ever that has been ratified by every country on Earth. As a result of this success, the ozone layer has overall remained remarkably healthy over the past few years, despite these odd seasonal and expected blips.
Good job, humans.