In the early 1980s, scientists sounded an alarm that sent shockwaves across the globe: a gaping hole was forming in the ozone layer above Antarctica every southern spring.
The ozone layer, located between 9 and 19 miles above Earth’s surface, acts like a planetary sunscreen by filtering out harmful ultraviolet (UV) radiation. Without this invisible shield, the risks of skin cancer, cataracts, and damage to ecosystems would rise dramatically.
The culprit was identified as chlorofluorocarbons (CFCs), once hailed as miracle chemicals for use in refrigerators, air conditioners, and spray cans. These compounds drifted into the stratosphere and destroyed ozone molecules at an alarming rate.
The discovery quickly shifted from a scientific finding to a global political crisis. Left unchecked, scientists warned, the ozone layer could collapse by the mid-21st century, exposing billions of people to dangerous UV radiation.
The Montreal Protocol
The global community responded with surprising speed. In 1987, nations adopted the Montreal Protocol on Substances that Deplete the Ozone Layer, a legally binding treaty that phased out the production of CFCs and other ozone-depleting substances.
Today, the Protocol has been ratified by 198 parties, making it the first treaty in history with universal global participation. Experts have called it “the most successful environmental agreement ever,” not just for its scope but for its impact.
Since its adoption, the Protocol has eliminated nearly 99% of controlled ozone-depleting substances, according to the United Nations Environment Programme (UNEP). The Kigali Amendment of 2016 extended its reach to phase down hydrofluorocarbons (HFCs), chemicals that don’t harm the ozone layer but are powerful greenhouse gases.
Environmental policy expert Durwood Zaelke calls it “a hell of an agreement,” which shows international cooperation can deliver measurable planetary benefits.
Signs Of Recovery, But Slowly
The ozone layer is steadily healing, though scientists avoid giving a single percentage because recovery varies across regions and years.
In 2024, the Antarctic ozone hole was the 7th smallest since tracking began in 1992, averaging about 20 million square kilometres during its peak season and reaching a maximum daily size of 22.4 million square kilometres, both lower than the long-term average.
The “ozone mass deficit,” a measure of how much ozone is lost, also fell to 46.1 million tonnes, below the 1990–2020 norm. Beyond Antarctica, upper stratospheric ozone levels outside the poles have been rising by 1–3% per decade since 2000, and global totals in 2024 were generally higher than the 2003–2022 average.
Scientists project that ozone will return to 1980 levels by around 2040 over the tropics and midlatitudes, 2045 over the Arctic, and 2066 over Antarctica. While some years still show larger ozone holes due to natural fluctuations, the overall trend is one of slow but steady recovery driven by the success of the Montreal Protocol.
The Antarctic ozone hole formed later than usual and closed relatively quickly, suggesting gradual but real progress. Still, experts caution against over-celebration. “One year does not make a trend,” says atmospheric chemist A. R. Ravishankara, emphasising that year-to-year variability can mask the long arc of healing.
The Complications Of Climate And Chemistry
Ozone recovery is not a simple straight line upward. Its production depends heavily on sunlight, with most ozone forming at the equator before drifting toward the poles. Phenomena such as El Niño, variations in solar activity, and large-scale atmospheric circulation patterns can accelerate or slow the healing process.
Climate change adds another layer of uncertainty: warmer stratospheric temperatures may influence ozone chemistry in ways scientists are still studying.
Another challenge lies in the dual role of ozone. While stratospheric ozone is protective, ozone in the lower atmosphere, the troposphere, is a harmful pollutant linked to respiratory illnesses and smog. Managing ozone, therefore, requires more than just watching the totals; it demands a layered approach to monitoring where ozone resides and how it shifts.
As Ravishankara notes, “You need to know not only the total amount of ozone above your head but also where it is.”
India’s Role In Ozone Protection
India has been a significant player in the success of the Montreal Protocol. As one of the largest producers and consumers of ozone-depleting substances in the 1990s, India’s commitment to phasing them out was critical.
By 2010, the country had eliminated CFC production, and in 2016, it joined the Kigali Amendment to phase down HFCs. The Ministry of Environment, Forest and Climate Change (MoEFCC) has since introduced a National Strategy for Phase-Down of HFCs, aligning industrial policy with environmental goals.
The benefits for India go beyond international goodwill. According to government and UNEP estimates, phasing out ozone-depleting substances has prevented over 20 million additional cases of skin cancer and cataracts globally each year, with a significant share of those benefits accruing in sun-exposed regions like South Asia.
For India, with its high levels of UV radiation and large agrarian economy, ozone protection safeguards not just human health but also crop productivity. Studies have shown that uncontrolled ozone depletion could have reduced yields of staples like wheat and rice by several percentage points annually.
Also Read: ResearchED: Here’s How The Supreme Court Grants Citizens A ‘Right Against Climate Change’
Accountability In The Recovery Phase
Scientists describe the current stage of ozone protection as the “accountability phase.” The infrastructure, satellites, ground stations, and international reporting systems exist to ensure that nations comply with their commitments and that progress continues.
The WMO emphasises that vigilance is necessary, since any resurgence in banned chemicals could derail decades of progress. In fact, in 2018, scientists detected unexpected emissions of CFC-11 from East Asia, a reminder that enforcement must remain robust.
Despite such incidents, global monitoring has largely succeeded in keeping countries on track. The decline of ozone-depleting substances in the atmosphere is a direct result of rigorous implementation.
The Montreal Protocol’s strength lies in its built-in adaptability, allowing for amendments and scientific updates as new threats emerge. This blend of scientific accountability and political flexibility remains its greatest asset.
Lessons For Global Environmental Action
The ozone story is often framed as a beacon of hope for tackling other planetary crises, particularly climate change. But the comparison has limits. CFCs were produced by a relatively small number of companies and industries, whereas carbon emissions are tied to every sector of the economy.
Nonetheless, the Montreal Protocol shows that swift, coordinated global action is possible when science and policy align.
Experts also warn that complacency could undo the gains. Political shifts, such as the U.S. withdrawal from global agreements under past administrations, threaten to weaken international resolve.
Yet, as Zaelke observes, the momentum for ozone recovery is strong enough to survive even wavering leadership. The key takeaway is that international agreements work, but only if nations remain committed to the long game.
A Planetary Win, With Caution
Four decades after the crisis was first identified, the ozone layer is healing, slowly but surely. The Montreal Protocol has not only curbed a planetary disaster but also saved an estimated two million cases of skin cancer annually, according to UNEP. It stands as proof that humanity can confront environmental crises with science-based, cooperative action.
Yet the story is not finished. With recovery timelines stretching into the mid-21st century, vigilance and political will remain crucial. As climate change intensifies, it will test the resilience of ozone recovery and the durability of international cooperation.
The ozone saga, then, is not just a story of healing skies; it is a reminder that the planet’s most daunting challenges can only be solved together.
Images: Google Images
Sources: World Economic Forum, Scientific American, MIT News
Find the blogger: Katyayani Joshi
This post is tagged under: ozone layer recovery, climate change, environment news, global warming, montreal protocol, nasa report, UN Environment programme, antarctica ozone hole, sustainable future, india climate action, air quality, green planet, environmental protection, global cooperation, science update
Disclaimer: We do not hold any right, copyright over any of the images used; these have been taken from Google. In case of credits or removal, the owner may kindly email us.
Other Recommendations:
Study Finds Disturbing Link Between Climate Change And Domestic Violence
