These days, it feels like every headline is a battleground. Left versus right, life versus choice, vax versus anti-vax – every issue seems to split us into opposing camps, each side shouting past the other. Some days, it’s hard to imagine humanity agreeing on anything ever again. So, consider this a palate cleanser. This week’s column is about something rare: a moment when the world didn’t just come together, but actually got it right. A global effort so successful, so decisive, that it stands as one of the greatest acts of collaboration in human history.

As a child growing up in the 90s, I was very stressed about the hole in the ozone layer. I’m not sure if the trigger for this stress was my anxiety-inclined personality (very likely) or the fact that I kept seeing posters of a sad-looking cartoon globe covered in plasters on the walls of my local library.

The message was clear: people had broken the planet, and now it was hurt. And, from what I understood at the time (I think I was 6), there wasn’t much we could do to fix it.

For a while, the ozone hole felt like an imminent, looming catastrophe. I remember looking up at the sky, half-expecting to see a gaping wound in the atmosphere, and wondering what would happen if it got bigger. Would the air get too hot? Would the sun burn us all? Would we have to live underground?

And then, at some point, the posters disappeared. The cartoon globe with its sad little bandages stopped staring at me from the library walls. The adults around me stopped talking about it. The world moved on, and so did I.

It wasn’t until recently that I found myself wondering: whatever happened to the ozone hole, and why haven’t I heard about it for the better part of a decade? Was this an example of scientists overreacting, or did we actually solve the problem? I did the research, and for once, I was very happily surprised by what I found. 

The great big hole in the sky

In the late 1970s, Jonathan Shanklin, a meteorologist with the British Antarctic Survey, was buried in data. While the rest of the world was busy embracing disco and bell-bottoms, he was holed up in a Cambridge office, sorting through decades’ worth of atmospheric readings from Antarctica. The British Antarctic Survey had been tracking ozone levels there since the 1950s, but for years, it all looked pretty uneventful; just a bunch of steady numbers that no one thought too hard about.

That is, until the numbers started changing.

Shanklin’s job was to digitise old paper records and crunch values from Dobson spectrophotometers (devices that measure atmospheric ozone). For nearly 20 years, the data had been rock solid, but in the late ‘70s, something shifted. Ozone levels started dropping, and not just by a little.

Shanklin flagged it, but his bosses weren’t convinced. Maybe it was an error. Maybe it was an anomaly. Maybe he was just being dramatic. Shanklin was frustrated by this response, but fortunately for us all, he wasn’t the only one raising alarm bells. Over in the US, two scientists – Mario Molina and F. Sherwood Rowland – had already published a 1974 paper suggesting that chlorofluorocarbons (CFCs), a group of chemicals widely used in refrigerators, air conditioners, and aerosol cans at the time, were quietly dismantling the Earth’s ozone layer.

At the time, CFCs were thought to be totally safe, and as you can probably imagine, a few big industries weren’t exactly thrilled about a couple of chemists suggesting otherwise. Molina and Rowland’s findings were met with all kinds of pushback: companies called them alarmists, other scientists were skeptical, and even worst-case predictions suggested only a minor impact, maybe a 2-4% decrease in ozone over the span of centuries.

Fast forward a decade, and reality was painting a much bleaker picture.

In 1985, Shanklin and his colleagues Joe Farman and Brian Gardiner published their findings, backed by credible data: the ozone over Antarctica had thinned dramatically, losing a third of its thickness over Halley Bay in just a few decades. Worse still, this wasn’t some far-off, slow-motion crisis. That infamous “minor depletion” that some scientists had predicted turned out to be a gaping hole in the sky, and it was getting bigger by the day. Satellite monitoring confirmed ozone depletion extended over a region of 20 million square kilometers.

Shanklin’s team had confirmed what Molina and Rowland had been warning about all along: CFCs were wreaking havoc on the atmosphere. The discovery was a wake-up call, forcing the world to face the fact that its obsession with convenient cooling and aerosol sprays had a serious downside. A decade later, Molina and Rowland got their well-deserved redemption (and a Nobel Prize in Chemistry).

As for Big Cooling – it was their turn to face the music. The world’s relationship with CFCs was about to change forever.

From panic stations to action plans

At first, world leaders weren’t exactly sprinting to tackle ozone depletion. Since the initial assumption was that any damage would be minimal and take centuries to unfold, their approach was cautious – maybe too cautious. In 1977, they put together a global action plan that mostly focused on gathering data: tracking ozone levels, studying the effects on people and ecosystems, and weighing the costs of actually doing something about it. The result was a lot of monitoring and not much action.

Sounds a bit like our current approach to climate change concerns, doesn’t it?

Then came the 1985 Vienna Convention. It was a step forward, sure, but it stopped short of enforcing any actual CFC cuts, which left many frustrated. A few months later, when the British Antarctic Survey confirmed that the ozone wasn’t just thinning but had a full-blown hole in it, those cautious early steps suddenly looked wildly inadequate. Cue the scramble.

Governments poured money into research, industries were forced to overhaul their reliance on CFCs, and against the odds, the world pulled off a rare act of unity. In 1987, the Montreal Protocol was signed, marking one of the greatest successes in international environmental cooperation to date. It remains the only treaty ever to be universally ratified, with every country on Earth committing to phasing out the chemicals responsible for ozone depletion.

But this was more than just a diplomatic victory. It was a masterclass in how global action should work. The treaty acknowledged “common but differentiated responsibilities”, ensuring that while developed nations led the charge with stricter deadlines, developing countries were given more time, backed by financial and technical assistance through a multilateral fund. This structure made compliance possible for all, setting a precedent that later climate agreements have struggled to match.

See what happens when we work together?

By the 1990s and early 2000s, the production and consumption of CFCs had been virtually eliminated. By 2009, 98% of the ozone-depleting chemicals targeted by the treaty were gone. Built to evolve, the Montreal Protocol has since undergone six amendments, tightening restrictions on replacement chemicals like HCFCs and HFCs as new science emerged. The most recent, the 2016 Kigali Amendment, will limit HFCs (which are potent greenhouse gases) and is projected to prevent up to 0.5°C of global warming by 2100.

The treaty’s impact has gone far beyond the ozone layer. The emissions reductions achieved by the Montreal Protocol were between 9.7 to 12.5 gigatons of CO₂ equivalent in 2010 alone. For context, that’s five to six times the target of the Kyoto Protocol, the landmark 1997 climate agreement. It’s easy to see why some argue that the Montreal Protocol has been the most effective piece of climate legislation ever implemented.

The public health benefits have been equally profound. By protecting the ozone layer, the treaty has helped prevent up to two million cases of skin cancer every year and has avoided millions of cataract cases worldwide. Had the world failed to ban CFCs, we’d be facing a very different reality today. Scientists estimate that by 2050, ozone hole-like conditions would have spread across the entire planet, exposing humans, animals, and ecosystems to unfiltered UV radiation at dangerous levels. The world as we know it would have been uninhabitable.

Instead, the Montreal Protocol gave us a fighting chance. Today, the ozone hole still forms over Antarctica every spring, but it closes up again over the summer as stratospheric air from lower latitudes drifts in, temporarily patching it up. And now, for the first time, there’s evidence of real recovery. The ozone layer is healing, more or less as expected. Scientific assessments predict that by the middle of this century, it will return to pre-1980 levels.

But healing takes time. Ozone-depleting chemicals are stubborn, some lingering in the atmosphere for 50 to 150 years before breaking down completely. And despite the Montreal Protocol’s success, there have been setbacks. In 2018, scientists noticed that levels of CFC-11, a chemical banned since 2010, weren’t dropping as quickly as expected. That meant someone, somewhere, was still producing it. An investigation led to illegal factories in China, where CFC-11 was being used in insulation foam. Once the findings became public, the Chinese government cracked down swiftly, shutting down the illicit production. Scientists say we are now back on track, but this example serves as a reminder that vigilance is key, even when a global treaty is in place.

We did it once before

The story of the ozone hole could have ended very differently. If world leaders had ignored the warnings, if industries had resisted change, or if the public had dismissed the science, we’d be living in a vastly different world; a world where stepping outside meant near-instant sunburns, where skin cancer rates had skyrocketed, and where entire ecosystems struggled under relentless UV radiation.

Instead, we got something rare: a success story. A moment in history where the world didn’t just talk about a crisis but acted decisively, collectively, and effectively. The Montreal Protocol is proof that when the stakes are high, collaboration can win over division. That science, when taken seriously, can guide policy. That global problems require global solutions, and that those solutions are possible.

We face enormous challenges today, each of them complex, each of them urgent. But if the ozone hole taught us anything, it’s that even the biggest crises aren’t insurmountable. When we work together and commit to real action, we can change the course of history. After all, we’ve done it before. 

About the author: Dominique Olivier

Dominique Olivier is the founder of human.writer, where she uses her love of storytelling and ideation to help brands solve problems.

She is a weekly columnist in Ghost Mail and collaborates with The Finance Ghost on Ghost Mail Weekender, a Sunday publication designed to help you be more interesting. She now also writes a regular column for Daily Maverick.

Dominique can be reached on LinkedIn here.