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Healing the Ozone layer

Healing the Ozone layer


The hole in the Earth’s Ozone layer is shrinking thanks to a landmark international agreement.

“Human action to save the ozone layer appears to have worked.”

BBC News

The Ozone layer is a sun shield – a thin part of the Earth’s atmosphere that’s 15 kilometres from its surface and protects us all from the harmful ultraviolet radiation.

If it’s not there then the sun can cause serious damage to life on Earth.

“Huge impacts on crops. If I go outside, 15 minutes and I’ll get a perceptible sunburn, in that world, it’s 5 minutes. This is an incredibly bad world.”

NASA Ted Talk

So when holes were discovered above the Arctic and the Antarctic, everyone was worried…

And as the hole over the Antarctic grew, so did the concern.

NASA’s satellites have been tracking them since 1979 and have produced images every year since.   

In the images of the Antarctic hole you can see Antarctica, the bottom of South America, Australia and the southern tip of Africa. The healthy parts of the Ozone layer are in red and the depleted bits are in blue. That is the hole.

Originally the scans showed a small blue blob over Antarctica. Then, as the years went by, the blue blob grew and grew.

It was at its largest in the year 2000, at 28.4 million kilometres squared. For context, that’s larger than all of North America. 

Then, in 2001, things started to change.      

The hole looked like it might be getting smaller – or at least it was no longer expanding uncontrollably. And it’s been good news ever since: the scans today show much less blue, and much more healthy red, which is down to that landmark international agreement.

“The phase out of nearly 99% of banned ozone depleting substances has succeeded in safeguarding the ozone layer leading to notable recovery of the ozone layer in the upper Stratosphere and decreased human exposure to harmful ultraviolet rays.”

UN Environment Programme

So how did countries manage to come together and make this happen?


The scientists who discovered the gaping hole in the ozone layer warned that humanity was on track to completely destroy it by 2050. But for an issue so big, the cause was actually something that seemed pretty small – everyday items found in every home…

“If you accept all newspaper reports, you might just believe that the next major threat to the world will come from [SFX spray] an aerosol can.”

BBC News Archive

Every time someone got ready for work, or a party, and sprayed a can of hairspray to fix their do, the gas from their canister would rise up and chip away at the ozone layer.

“They are used in every air conditioner and refrigerator, they are used in car air conditioning, they are used in a bunch of industrial processes to make electronic equipment.”

Tortoise Slow Newscast

Luckily, there were already lots of less harmful alternatives, but that didn’t stop big chemical companies from resisting change and questioning the science: 

“Someone from the French industry insisted that, patronisingly, that French women would never give up CFCs in their perfumes and in their hairsprays because French women were able to tell the difference between aerosols with CFCs and the alternatives.”

Tortoise Slow Newscast

It didn’t work though. Public opinion turned against CFCs rapidly, and so politicians had to act – and act fast. 

Just two years after the official discovery of the CFC problem, world leaders gathered in Canada to try and fix it.     

The result was the 1987 Montreal Protocol…

“Mr President, the evidence is there. The damage is being done. What do we, the international community, do about it?”

Margaret Thatcher

46 countries signed up. They would stop producing CFCs, and phase out using them too.

That was 35 years ago and now a report from the UN says we’re reaping the rewards of that agreement. It says that the current date of full Ozone recovery is 2040. It will take time to heal completely because the harmful CFC gases can live in our atmosphere for as long as 150 years. 

What is undeniable though, is that if politicians hadn’t acted so fast and so decisively all those decades ago, we would be living in a far worse place today. 

So what can we learn from this rare success story? 


“We can look back on those choices we made in the 80s and the early 2000s, I know with certainty that they were the right ones.”


The Montreal Protocol is the most successful environmental agreement in human history and is still the only UN treaty to be universally agreed: every single country signed up. 

If the world can come together to prevent an environmental catastrophe once, can we do it again? 

There are many parallels between today, and 1987: humanity is once again facing an environmental catastrophe. We are at a crossroads: 

“People are dying, people are suffering, entire ecosystems are collapsing.”

Greta Thunberg

In 2015 world leaders did sign a major treaty called the Paris agreement. The main goal was to stop the world’s average temperature rising more than two degrees, or ideally 1.5 degrees celsius. 

Many were optimistic at the time, but it now looks like we’re far off meeting that target. The success of the Montreal Protocol is evidence that we can come together to repair damage that humans did to the planet, but with the state of the world as it currently is, international agreement on anything looks tricky.

This episode was written and mixed by Rebecca Moore.