What happens in the stratosphere stays in the stratosphere? How does the ozone hole affect weather and climate? Earlier this month, the Copernicus Atmospheric Monitoring Service (CAMS) team reported that the 2021 ozone hole is one of the largest on record, in fact “more than 75 percent of ozone holes at this stage of the season since 1979.”
Lately, it’s even bigger than Antarctica itself. But aside from increased UV radiation over the Frozen Continent, how does the ozone hole affect you and me? Is climate change and global warming making this worse, or is it just overly tanned penguins and algae blooms at the bottom of the world?
Last year study published in the journal Nature saw a clear correlation between the possible recovery of the ozone layer, which the study links to a CFC ban under the Montreal Protocol, and a “pause” in atmospheric circulation trends in the Southern Hemisphere.
Since the 1990s, scientists have observed several changes in weather patterns in the Southern Hemisphere that have been linked to ozone depletion. These include reducing rainfall over Australia or extending South America’s tropical rain belt to Uruguay or northern Argentina, opening up new fields for agriculture on lands that were previously too dry.
The Nature study was updated in January 2020, just after the ozone hole reached its smallest size ever recorded, raising optimism about how it will develop in the future.
Is it too early to claim victory?
Then came the 2020 season, when scientists observed the longest ozone hole ever recorded, lasting until the end of December, with a huge surface area of almost 25 million square meters at its maximum.
And now the ozone layer is behaving unexpectedly again this year, with a sudden rise in September.
Meanwhile, on the other side of the planet Earth the amazing Arctic ozone hole appeared in March 2020right in the midst of the COVID-19 lockdown.
Speaking of the 2020 Nature study, Vincent-Henri Pesch thinks we may have claimed victory too soon. “The document stated that the Montreal Protocol allowed not only to make the ozone hole disappear, but also to counteract the advancement of the polar vortex to the South Pole, moving it further. It was released in 2020, after a particularly small ozone hole. I think it was a little cheeky because we saw a lot of variability from year to year.”
So it’s all for nothing?
Does this mean that the Montreal Protocol to Ban Ozone Depleting Gases is ineffective? Not in terms of reducing CFC emissions, says the director of CAMS. “We are on the right track. As for chlorine and bromine levels, they started to decline after the adoption of the Montreal Protocol, but in terms of the ozone layer, we do not yet have signs of a proper recovery.”
“If we continue to avoid CFC emissions, we will return to normal, but slower than expected, possibly due to climate change,” Peuch told Euronews. “We expect the ozone hole to be closed by 2060 or 2070, so the scale of two or three years doesn’t provide enough perspective.”
How does the ozone hole affect weather and climate?
it widely accepted that the ozone hole is pushing the polar vortex further south, squeezing it around the pole, and as it gets smaller, its winds get stronger as well.
This affected the circulation in the Southern Hemisphere. Some of them are well-studied by scientists, but Vincent-Henri Pesch warns against jumping to conclusions: “It’s all about fluids, so everything is interconnected. These planetary movements are not independent, but how exactly do they interact?
“It’s difficult to pinpoint very direct mechanisms of cause and effect,” says Peuch. “We’re seeing long-term trends and we’re able to understand that if the polar vortex is smaller, the Hadley cell can get bigger, and we can learn how weather patterns, rainfall here and there could change.”
While climate scientists today understand some of the correlations between the ozone hole and weather patterns, the interactions between the stratosphere and troposphere are not yet well known, Peuch said. “It’s still difficult for climate models to reproduce what’s happening in the stratosphere, we have far fewer observations than the troposphere.”
“We still have a lot of work ahead of us to properly understand the relationship between what happens in the stratosphere and the effects at our level, on weather events, rainfall, storms and so on,” he says. linking anomalies in the stratosphere to weather trends would greatly enhance our seasonal forecasting capabilities as well as our Climate Change Service but as far as I know there is no such model.” Peuch believes science should remain modest about its ability to make direct connections.
The ozone hole actually has a slight cooling effect as it vents greenhouse gases into space.
UV radiation has some impacts on the Antarctic ecosystem, not yet fully understood, contributing to the decomposition of organic matter, increasing greenhouse gas emissions and warming the ocean. UV radiation has no direct warming effect.
Its incidence in skin, eye, or immune system disorders is well known.
Then how does climate change affect the ozone hole?
Global warming is making our troposphere warmer but tends to cool the stratosphere, enhancing the polar vortex’s ability to deplete the ozone layer.
Ozone depletion mainly affects the Southern Hemisphere during springtime (August – September) because the South Pole meets the necessary conditions more often: extreme cold (-80º C), polar stratospheric clouds and CFC gases create a hole in the ozone layer.
According to some studiesthe staggering Arctic ozone hole in March 2020 may have been caused by record high temperatures in the North Pacific.
Tiny 2019 ozone hole emerged rare sudden stratospheric warming.
So it is likely that climate change will make these conditions more frequent. “We expect climate change to delay the recovery of the ozone layer,” says Peuch, recalling that given the variability of previous seasons, we cannot yet speak of clear trends in the recovery of the ozone layer.