For decades, scientists have closely observed the ozone layer, which protects Earth from the sun’s harmful ultraviolet (UV) radiation. This year, just in time for World Ozone Day, the European Union’s Copernicus Atmosphere Monitoring Service (CAMS) announced the state of the ozone hole — its size is the smallest it has been in the past 30 years.
Ozone is created in our atmosphere when the sun’s high-energy UV rays rupture the stable covalent bonds of atmospheric oxygen (O2) molecules, transforming them into free radicals. Free radical oxygen atoms, being charged particles, readily react with other oxygen molecules to form ozone (O3). In nature, ozone molecules continually cycle so that they form and re-form at equilibrium.
However, the late 1970s saw scientific acknowledgment that pollutants from industrial and consumer emissions of chlorofluorocarbons (CFCs) prevent the normal balanced reformation of ozone, foreshadowing a weakened ozone layer. By 1985, the first recognized “ozone hole” — a patch of thin ozone layer in the upper atmosphere — was detected, alarming scientists and policy makers alike.
Two years later, in August 1987, the Montreal Protocol, a landmark international agreement, banned production and use of ozone-depleting substances. A few weeks afterward, the United Nations designated September 16 as International Day for the Preservation of the Ozone Layer — more commonly known as World Ozone Day — to spread awareness for stewardship of our planet’s fragile ozone layer.
Since then, scientists and researchers, like those at CAMS and the intergovernmental World Meteorological Organization (WMO), have meticulously tracked the ozone hole. Daily readings are documented thanks to a worldwide cooperative network of stations. Interestingly, the WMO projected that a recovery of the ozone layer to pre-1970s levels might be foreseeable around the year 2060. But this year’s findings could alter those projections.
The 2019 hole is appearing to be the smallest size it has been in the past three decades, and its behavior has been intriguing. A polar vortex in early September affected the hole’s opening, then displaced the hole so that it was off-center and “far from the pole.”
“This year, we have seen that the ozone hole has been particularly unusual,” said Antje Innes, senior scientist at CAMS. “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.”
The deputy lead at CAMS, Richard Engelen, shared that the small size of this year’s ozone hole is encouraging, but there is still a need for further study. “Right now, I think we should view this as an interesting anomaly,” Engelen said. “We need to find out more about what caused it.”
Image via CAMS