‘Tis the season for the hole in the ozone layer to undergo its annual growth spurt in the skies high above Antarctica. It’s still early days, but scientists say this year’s version is behaving unusually and that it has the potential to be the smallest hole observed in over three decades.
Yesterday was International Day for the Preservation of the Ozone Layer, and so we present to you some good news about Earth’s atmosphere. Recent observations by the Copernicus Atmosphere Monitoring Service (CAMS) – a European Union-run service that continually monitors the state of the atmosphere – suggests the 2019 ozone hole above Antarctica “could have the smallest area of any Antarctic ozone hole since the mid-eighties,” according to a CAMS press release issued on September 9, 2019. In the week since, the ozone hole has continued to behave strangely, but in a manner consistent with a smaller hole than usual, according to CAMS.
The ozone hole forms every year during the Antarctic spring, starting in late August and ending in December, during which time the amount of ozone in the Earth’s stratosphere above Antarctica can be depleted by as much as 60 percent. During the first few days and weeks of this year’s ozone hole season, however, the gap in the atmosphere hasn’t opened up in its typical fashion; the hole is well under the size usually seen by this time of year. What’s more, the hole is not immediately above the south pole, instead appearing closer to South America.
“This year, we have seen that the ozone hole has been particularly unusual,” Antje Inness, a senior scientist at CAMS, said in today’s press release. “Although it started growing relatively early, at the beginning of September a sudden warming of the stratosphere disturbed the cold polar vortex that gives rise to the ozone hole.”
According to CAMS, the warmer stratosphere has resulted in fewer stratospheric clouds, which in turn results in less ozone being depleted. Meanwhile, the hole’s unusual orientation in the direction of South America means ozone-rich air from outside the vortex can trickle in, resulting in a smaller ozone hole.
The area of the 2019 ozone hole compared to the other holes since 2003. Image: Copernicus Atmosphere Monitoring Service, ECMWF
CAMS observations from last week revealed an area of ozone thinning spanning around 5 million square kilometres (1.9 million square miles), whereas by this time in 2017 it had already stretched to 20 million square kilometres (7.7 million square miles), reported the BBC, which noted that “there is a good degree of variability from year to year.”
The hole is currently toggling through phases of growth and diminishment, but it has been stabilising over the past few days. The forecast from CAMS suggests it will remain small this week, and that it’s still on track to become the smallest hole seen in 30 years, said Inness.
And thank goodness for that. Ozone is a critically important molecule that protects the Earth’s surface from the Sun’s harmful ultraviolet rays. Atmospheric ozone exists in a perpetual cycle of birth and destruction that under normal circumstances would be in a state of equilibrium. Human activities, however, such as the release of halocarbons, disrupts this happy equilibrium, contributing to the depletion of the ozone layer, which resides between 20 to 30 kilometres (12 to 18 miles) above the surface.
The world’s attention was directed to the ozone layer in the mid-1980s, when scientists detected a frightening gap, resulting in the 1987 Montreal Protocol. As hard as it is to believe by today’s standards – with our baffling inability to reach global consensus on human-caused climate change – the world got its collective ass together to curb emissions of ozone-depleting halocarbons, from compounds produced by fridges and air conditioners to aerosol sprays and medical sterilisers. Today, the Montreal Protocol includes 196 signatories, and it appears to be working. The healing ozone layer is recovering, albeit slowly. The ozone layer is expected reach pre-1980s levels in about 40 years, according to a UN report from last year.
That said, the unusually small ozone hole observed this year cannot be linked to the Montreal Protocol.
“It’s not really related to the Montreal Protocol where we’ve tried to reduce chlorine and bromine in the atmosphere because they’re still there,” Richard Engelen, the deputy head at CAMS, told the BBC. “It’s much more related to a dynamical event. People will obviously ask questions related to climate change, but we simply can’t answer that at this point.”
That the small ozone hole might be connected to climate change would be, in a word, ironic. Engelen said more research is need to fully understand the nature of this year’s ozone hole.
All this said, we should continue to uphold the Montreal Protocol and ensure constant cooperation from the world’s nations.
Last year, for example, scientists detected a mysterious surge of unauthorized CFC-11 emissions, which was later traced to eastern China. The Chinese government dealt with the situation to keep it compliant with the Montreal Protocol, but the episode demonstrated the importance of monitoring the environment for potential transgressors. Keeping the planet safe from those who willingly choose to abuse it requires constant vigilance.