The ozone layer is healing - will the hole disappear for good?

A recent study confirmed that the Antarctic ozone layer is currently healing, as a result of global efforts to reduce ozone-depleting substances. 

The study demonstrates that joint international measures – in particular, the phase-out of chemicals that damage the ozone layer – have led to a meaningful restoration of this critical atmospheric shield.

Scientists, including the MIT team that led the current study, have previously detected indications of ozone recovery.

However, this new study is the first to provide strong statistical evidence that the improvement is primarily driven by the reduction of ozone-depleting substances, rather than factors like natural weather fluctuations or rising greenhouse gas levels in the stratosphere.

Recovery of the ozone hole

“There’s been a lot of qualitative evidence showing that the Antarctic ozone hole is getting better. This is really the first study that has quantified confidence in the recovery of the ozone hole,” said study co-author Susan Solomon, a professor of environmental studies and chemistry at MIT. 

“The conclusion is, with 95 percent confidence, it is recovering. Which is awesome. And it shows we can actually solve environmental problems.”

Solomon worked on this project with lead author and graduate student Peidong Wang and contributors from multiple other research institutions. 

The team’s findings offer strong support for the success of international policy interventions – specifically the Montreal Protocol, which curbed the production of ozone-depleting substances such as chlorofluorocarbons (CFCs).

Seasonal ozone hole over Antarctica 

Within the Earth’s stratosphere, ozone is a naturally occurring gas that acts as a sort of sunscreen, protecting the planet from the sun’s harmful ultraviolet radiation. 

However, in 1985, scientists discovered that a seasonal “hole” in the ozone layer developed over Antarctica each austral spring – letting in greater quantities of dangerous UV rays. 

By 1986, Solomon, then a scientist at the National Oceanic and Atmospheric Administration (NOAA), led expeditions that identified CFCs as the chief culprit in stratospheric ozone loss. The Montreal Protocol, enacted in 1987, aimed to gradually eliminate these chemicals worldwide.

Natural and human-caused changes 

“While detecting a statistically significant increase in ozone is relatively straightforward, attributing these changes to specific forcings is more challenging,” Wang said. 

In past studies, although ozone levels in the Antarctic region seemed to be improving, scientists struggled to confirm just how much of that recovery was driven by reductions in CFCs as opposed to natural weather variability – such as El Niño, La Niña, or the polar vortex – or the effects of rising greenhouse gases.

To tackle these uncertainties, the researchers adopted a “fingerprinting” method, originally developed by Nobel Prize-winning scientist Klaus Hasselmann for distinguishing the impacts of human-caused climate change from natural fluctuations in the climate system. 

The MIT-led team adapted this fingerprinting to separate human-driven ozone gains from other atmospheric noise.

They began by running climate simulations for various scenarios: a hypothetical world where greenhouse gases did not rise, a world where ozone-depleting substances were not phased out, and other alternative pathways. 

In these virtual settings, they examined how ozone levels would shift, both over time and with seasonal changes. By comparing these model outcomes, the scientists identified a characteristic signal of ozone healing – an unmistakable pattern that occurred only when CFCs were curbed.

Distinct “fingerprint” in the data

The researchers then combed through 15 years’ worth of satellite observations of the Antarctic ozone hole.

Step by step, they tested whether the actual data exhibited the predicted pattern of recovery – a fingerprint tied specifically to the global phase-out of CFCs. The match was impressively strong.

“After 15 years of observational records, we see this signal to noise with 95 percent confidence, suggesting there’s only a very small chance that the observed pattern similarity can be explained by variability noise,” Wang said. 

“This gives us confidence in the fingerprint. It also gives us confidence that we can solve environmental problems. What we can learn from ozone studies is how different countries can swiftly follow these treaties to decrease emissions.”

Lessons from the healing ozone hole

The study’s findings imply that if these trends persist, the Antarctic ozone hole could eventually close for good. 

“By something like 2035, we might see a year when there’s no ozone hole depletion at all in the Antarctic. And that will be very exciting for me,” Wang said. “And some of you will see the ozone hole go away completely in your lifetimes. And people did that.”

From a broader perspective, the ozone hole’s gradual healing stands as a success story for international cooperation on an environmental crisis. 

At the height of CFC use, aerosol propellants, refrigerants, and other industrial processes threatened to erode Earth’s UV shield to dangerous levels. Rapid science-based policymaking in the form of the Montreal Protocol turned the tide, demonstrating that even large-scale environmental challenges can be confronted.

The researchers consider this a timely lesson for today’s leaders, as the world grapples with complex ecological problems, including climate change. 

By illustrating how robust, evidence-based treaties can drive positive, global-scale outcomes, the current work highlights both the vulnerability of Earth’s atmosphere and the power of coordinated human action.

The study is published in the journal Nature.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates.

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–