The ozone layer over Antarctica, damaged by air pollution decades ago, has fortunately been recovering in recent years. Scientists have observed gradual ozone restoration since the 2000s, but now, one study all but confirms that this positive trend is a result of reduced ozone-depleting chemicals in the atmosphere.
The study, recently published in Nature, reveals a bright spot in the current climate outlook. Testing simulations based on different climate factors, researchers seemingly confirmed that efforts to limit the emission of chlorofluorocarbons (CFCs) — chemicals that contain carbon, chlorine, and fluorine — are the main reason why ozone recovery is seeing continuous success.
A Hole in the Sky
Ozone, a gas composed of three oxygen atoms, naturally occurs in the Earth’s upper atmosphere (stratosphere) and lower atmosphere (troposphere). In the stratosphere, it forms a protective layer around 6 to 30 miles above the Earth’s surface, partially shielding it from harmful solar ultraviolet radiation; when exposed to an excess of UV radiation, humans can develop sunburn or, worse, skin cancer.
Around the late 1970s into the 80s, all eyes were on the ozone layer. Using satellite measurements, scientists realized that ozone loss above Antarctica was snowballing at a concerning rate, having torn a hole in the layer. The culprit behind this damage, they discovered, was CFCs, which were commonly used in aerosol sprays and refrigerants after their development around the 1930s.
Although not harmful in the lower atmosphere, once CFCs reach the stratosphere and begin to break down, they wreak havoc on the ozone layer by releasing chlorine. Due to colder temperatures and isolation from mid-latitudes by the polar vortex (a strong system of wind near the Earth’s polar regions), the atmosphere above Antarctica is particularly vulnerable to accelerated ozone depletion from chlorine accumulation.
Read More: Whatever Happened to the Hole in the Ozone Layer?
Finding the Right Fingerprint
Recent research, however, has provided a glimmer of hope for the future of the ozone layer. The push to reduce CFC emissions has shown tremendous progress ever since the inception of the Montreal Protocol, a 1986 global treaty enacted to phase out ozone-depleting substances.
Observations of ozone recovery have mainly been qualitative. The new study, instead, took a quantitative approach to ozone layer observations, with a particular focus on a technique called fingerprinting. In climate studies, fingerprinting separates the influence of specific climate factors from natural, meteorological conditions.
The researchers first crafted simulations of the Earth’s atmosphere that featured multiple parallel worlds, each one with the same global atmosphere but different starting conditions. One simulation, for example, centered around conditions of no increase in greenhouse gases or ozone-depleting substances. A change in the ozone layer here, as a result, would be caused by natural weather variability.
Comparing these varying simulations and mapping out the times and altitudes where ozone recovered from month to month, the researchers landed on a fingerprint, or a pattern of ozone recovery that resulted from conditions of reduced ozone-depleting substances.
Hope for the Future
The researchers then viewed this fingerprint through the framework of actual Antarctic ozone hole satellite observations from 2005 to present day. The fingerprint began to align with the satellite patterns recorded over the years, leading them to conclude with 95 percent confidence that ozone recovery is a result of reductions in ozone-depleting substances rather than meteorological changes related to the polar vortex or El Niño/La Niña.
If the ozone layer continues to heal at this rate, it may eventually remain fully intact, closing the hole. The researchers propose that ozone hole depletion could potentially slow to a halt by sometime around 2035. Such a positive trend could further empower scientists in the fight against climate change, knowing that environmental issues can be fixed in the decades to come.
Read More: How the Ozone Layer Evolved and Why It’s Important
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
NOAA. CFCs and their substitutes in stratospheric ozone depletion.
MIT. Study: The ozone hole is healing, thanks to global reduction of CFCs
Jack Knudson is an assistant editor at Discover with a strong interest in environmental science and history. Before joining Discover in 2023, he studied journalism at the Scripps College of Communication at Ohio University and previously interned at Recycling Today magazine.
