The ozone layer is still healing…thanks to science

Summary

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Short Wave Podcast Summary

Episode: "The ozone layer is still healing…thanks to science"
Date: January 13, 2026
Host: Emily Kwong
Guest: Irina Petropadlovskik, Atmospheric Scientist
Duration: ~13 minutes

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Overview

This episode explores the science behind the healing of the ozone layer, tracing the historical context of its depletion, the human-made chemicals responsible, and the global scientific and policy response that led to its ongoing recovery. Host Emily Kwong and atmospheric scientist Irina Petropadlovskik break down how the ozone layer works, what caused the "hole" over Antarctica, the monumental effort to reverse the damage, and why this global success story offers lessons for tackling climate change.

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Key Discussion Points & Insights

1. What is the Ozone Layer and Why Does It Matter?

• Ozone’s Role:
  • The ozone layer, found in the stratosphere, acts as Earth's sunscreen, absorbing harmful ultraviolet (UV) radiation.
    • “Without ozone, that would be impossible to live on Earth.” — Irina Petropadlovskik [00:31]
  • Ozone (O₃) is formed and destroyed by sunlight; its balance shifts with the seasons.

2. Discovery of the Ozone Hole

• Historical Context:

  • Starting in the 1970s, scientists observed declining ozone levels above Antarctica, culminating in the discovery of the 'ozone hole' in the 1980s.
    • “Scientists noticed that ozone is changing slowly but surely. But they didn't know how much... until maybe the beginning of 80s when the scientists actually measured significant change.” — Irina [01:20]
  • The so-called "hole" is actually a severe thinning detected in Antarctic spring (October).

• What Caused It?

  • Weather balloon measurements found elevated levels of chlorine and bromine, which rapidly destroy ozone.
    • “High levels of two chemicals, chlorine and bromine, were breaking down ozone faster than it was being made, letting in the kind of radiation that causes cancer, crop failure...” — Emily [01:47]
  • These chemicals originated from human use of CFCs (chlorofluorocarbons) and related substances in refrigeration, firefighting, fumigants, and aerosols.

3. The Science of Ozone Depletion (and Antarctic Specifics)

• Seasonal Fluctuations:

  • In Antarctica, ozone concentrations are highest during December and January due to sunlight-driven production; they remain steady in the polar night (winter), when there is no sun.
    • “In Antarctica, the maximum of the ozone is happening during months of December, January... And then when the polar night comes in, there is not much ozone production.” — Irina [04:00]
  • The Antarctic polar vortex creates strong wind boundaries that isolate polar air, preventing mixing with other latitudes.
    • “They separate the air that's over Antarctica from... outside. So there is no really way to mix it with other airflow.” — Irina [04:58]

• How Pollutants Travel:

  • CFC chemicals, used widely on Earth, persist and migrate upwards through atmospheric mixing and specific global circulation patterns (e.g., Brewer-Dobson circulation).
  • Special polar stratospheric clouds in Antarctica enable chlorine and bromine to become highly reactive, triggering rapid ozone destruction when spring sunlight returns.
    • “They set them up such that there will be only chlorines and bromines released once the sun comes back... and then those chemicals are released and they start to destroy ozone very, very rapidly.” — Irina [08:04]
  • One chlorine atom can destroy over 100,000 ozone molecules. [06:24]

4. Global Response: The Montreal Protocol

• Scientific Alarm, Political Action:
  • Scientists presented evidence to the public and governments, resulting in the Vienna Convention and ultimately the 1987 Montreal Protocol, under which every country agreed to phase out ozone-depleting substances.
    • “Agreed to stop production and use of those ozone depleting substances.” — Irina [09:41]
  • Industry transitioned to safer chemical alternatives; developed countries funded technology changes in developing nations.

5. Why The Ozone Layer is Still Recovering

• Longevity of Chemicals:
  • Some CFCs persist in the atmosphere for up to a century, so despite bans, recovery is slow but ongoing.
    • “Some chemicals actually... can live up to 100 years. So... they have quite a long way to go before they get completely removed from the stratosphere.” — Irina [09:57]
• Continuous Monitoring:
  • Scientists continue to observe the ozone, as new replacement chemicals may have different environmental impacts, including as greenhouse gases.
    • “We still need to monitor it... Some of them are so-called greenhouse gases. So they're heating the atmosphere.” — Irina [10:28]

6. Lessons for Addressing Climate Change

• Success Factors:
  • The ozone issue was resolved more quickly than climate change challenges for several reasons:
    • The problem affected everyone.
    • Giving up CFCs was less disruptive than ending fossil fuel use.
    • Industry and governments cooperated and supported transitions globally.
      • “Giving up CFCs was a lot easier than giving up like oil and gas.” — Emily [11:38]

7. Personal Reflection and Hope

• Scientists’ Perspective:
  • Irina expresses optimism about humanity’s ability to collaborate and solve global environmental crises, hoping to see full ozone recovery expected by 2050–60.
    • “It's just really good to see that ozone is on the way to recovery. It's in the 2050s, 60s... when people expect the full recovery of the ozone.” — Irina [12:20]

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Notable Quotes & Memorable Moments

• On the importance of ozone:

  • “Without ozone, that would be impossible to live on Earth.”
    — Irina Petropadlovskik [00:31]

• On ozone’s chemical vulnerability:

  • “One chlorine atom can destroy over 100,000 ozone molecules.”
    — Emily Kwong [06:24]

• On the global response:

  • “The Montreal Protocol in 1987... signed by every country, I mean this is really amazing. Agreed to stop production and use of those ozone depleting substances.”
    — Irina Petropadlovskik [09:41]

• On why the world acted so decisively:

  • “Giving up CFCs was a lot easier than giving up like oil and gas.”
    — Emily Kwong [11:38]

• On scientific hope:

  • “It's just really good to see that ozone is on the way to recovery. Maybe I will live long enough to see that.”
    — Irina Petropadlovskik [12:20]

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Key Segment Timestamps

| Segment Topic | Time | |--------------------------------------|-----------| | Ozone basics & importance | 00:00–01:20 | | Discovery of Antarctic ozone hole | 01:20–01:47 | | The chemistry behind ozone depletion | 04:00–08:49 | | Global response (Montreal Protocol) | 09:05–09:41 | | Why is recovery slow? | 09:57–10:20 | | Ongoing monitoring & greenhouse gases| 10:20–10:59 | | Lessons for climate change | 11:19–11:42 | | Scientist reflection & hope | 12:11–12:45 |

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Summary Takeaway

The story of the ozone layer’s healing is a testament to the power of global scientific collaboration and swift policy action. Despite persistent challenges, it offers hope and practical lessons for tackling other planetary issues, most notably climate change. As Irina and Emily underscore, the success of the ozone recovery shows that humanity can respond forcefully and effectively when science, industry, and international cooperation align.

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Transcript

[A]

This message comes from Mint mobile. Starting at $15 a month. Make the [e-mail] Switch $45 upfront payment for three months. Five gigabyte plan equivalent to $15 a month. Taxes and fees extra first three months only. See terms. You're listening to Shortwave from NPR. Hey Shortwavers, Emily Kwong here with a love letter to the layer of the Earth's atmosphere that acts like a sunscreen. I'm talking, of course, about ozone.

[B]

Without ozone, that would be impossible to live on Earth.

[A]

This is atmospheric scientist Irina Petropadlovskik. The ozone is a layer of the stratosphere with a high concentration of ozone molecules, each one made out of three oxygen atoms.

[B]

And it's very good for us. It protects us from the harmful UV radiation. And that's why we want more of this, not less of that.

[A]

To form ozone needs sunlight, which bursts oxygen apart. You know, the O2 version we breathe. And then each single atom of oxygen can then connect with another O2 to form our girl O3, aka ozone. But sunlight can also destroy ozone, and the balance generally depends on the season. But Starting in the 1970s, something weird happened.

[B]

Scientists noticed that ozone is changing slowly but surely. But they didn't know how much it's changing until maybe the beginning of 80s when the scientists actually measured significant change. And it was happening in the springtime in Antarctica. And so they noticed that there was less ozone.

[A]

A giant hole is forming in the.

[B]

Earth's protective ozone layer. Scientists discovered a hole, the remarkable loss.

[A]

Of ozone that occurs over the Antarctic in October. A lot of people call it the ozone hole, but it was really more of a thinning. Scientists launched weather balloons to study its size. And they found something shocking. High levels of two chemicals, chlorine and bromine, were breaking down ozone faster than it was being made, letting in the kind of radiation that causes cancer crop failure. And it was happening because of ozone depleting substances made by us on Earth. So the race was on to save the world. Today on the show, how researchers mobilized on a global scale to close the ozone hole. Plus why the ozone layer is still recovering and what climate scientists can learn from this success. You're listening to Shortwave, the science podcast from npr.

[C]

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[A]

This message comes from Whole Foods Market. Follow your wellness goals and save big with sales on supplements and vitamins. And explore an abundance of high quality multivitamins, probiotics and protein powders. Keep good habits going strong. Cook homemade meals featuring sustainable wild caught sockeye salmon and many more delicious and lean protein options for wellness when you need it. Shop smart meal shortcuts to stay motivated like ready to eat salad kits. Shop all things wellness at Whole Foods Market. So, Irina, I want to focus on how the ozone is operating over Antarctica because that's where the hole is is. And I know that the ozone layer over Antarctica naturally thins because things are a little different there, right?

[B]

Yeah. In Antarctica, the maximum of the ozone is happening during months of December, January, and it's happening naturally. You know, there is a increase in ozone throughout the year. And then when the polar night comes in, there is no sun. And so there is no much of the ozone production happening during the wintertime.

[A]

And that's because sunlight triggers ozone formation, but also sunlight destroys ozone. So the amount of ozone is always kind of fluctuating when the sun is present. And during the Antarctic polar night in June, July and August, when there's no sun, the ozone amounts are basically steady. They don't really fluctuate.

[B]

Yeah.

[A]

And then in the spring, the sunlight comes back and these chemical reactions start happening again. But isn't the Earth's atmosphere always moving and mixing? So, like, wouldn't the air from other parts of the world that have access to sunlight mix with Antarctica's air?

[B]

Antarctica has a very specific process. Because it's a continent, the atmosphere can create these strong winds that circulate around Antarctica. And so they separate the air that's over Antarctica from the rest of the other latitudes outside of Antarctic vortex. So there is no really way to mix it with other airflow.

[A]

Oh, okay. So the atmosphere of Antarctica is isolated because of this polar vortex, which results in this seasonal cycle that has its rhythms. Now let's go back in time when scientists really started noticing the ozone layer was changing over Antarctica beyond what was typical for the seasonal rhythm. And these researchers went on an expedition to Antarctica to figure out why. What did they do?

[B]

So scientists flew into Antarctica on the aircraft and they also set up the camp on Antarctica continent. But what the most interesting observation they made is that when they're flying Inside of Antarctica, they continuously measured both ozone and chlorines, the chemicals that they thought that might be destroying ozone. And they noticed that flying into Antarctica, the ozone started to go down and chlorine started to go up. And so that made very good sense to them. So that those chemicals are destroying ozone.

[A]

It's like their Achilles heel. I read that one chlorine atom can destroy over 100,000 ozone molecules.

[B]

Yeah, definitely.

[A]

What the heck were we doing in the 50s and 60s that created this abundance of chemicals in the atmosphere?

[B]

Yeah, chemicals that we can use in refrigeration. Those chemicals were put in the firefighting equipment, for example. They were very effective at that. They were put in the aerosols sprays. And so they've been used for fumigation of the vegetables and the fruits. So they were working really well. But what I think people did not realize right away is that those chemicals actually are capable of escaping into the stratosphere.

[A]

But I'm like, curious, like, how did stuff made on Earth produce molecules that got all the way up there? Because the stratosphere is miles above our heads. It's like where planes fly. Like, how could chemicals travel upwards that high?

[B]

Well, the atmosphere has this mixing properties. You know, there are a lot of exchange between the troposphere and stratosphere in the tropics. And they can travel also with this flow of the air from the tropics into the middle latitudes and the polar regions. There is the so called Burr Dobson circulation in the atmosphere, and they get distributed everywhere.

[A]

So they hang out a long time.

[B]

And then they can hang out for a long time. Yes. Oh, there's another thing that we need to remember. There is also the specific clouds that are formed in Antarctica and they're called the polar stratospheric clouds.

[A]

Polar stratospheric clouds.

[B]

So they're also very quite essential for this depletion to occur. And the reason for that is that they actually set up this activation of the chlorines that are typically not very active. So they set them up such that there will be only chlorines and bromines released once the sun comes back. And so then those chemicals are released and then they will start to destroy ozone very, very rapidly. But there are also other chemicals that get frozen into the pulse transfer clouds that typically neutralize these reactions. And so there is nothing to stop those chemicals. Chemicals to destroy ozone for some period of time until the polar specific clouds disappear.

[A]

What?

[B]

Yeah.

[A]

What an accumulation of forces that led to this problem. Okay, so what did scientists do in Response because obviously today the ozone is okay. So what happened ultimately to save the world.

[B]

Right, exactly. So they started to present their findings to the public, to the governments. And so eventually they got enough people who listened to their worries that the Vienna Convention happened where the representatives from many, many countries got together and they discussed these issues. And then the Montreal Protocol in 1987 actually signed by every country, I mean this is really amazing. Agreed to stop production and use of those ozone depleting substances.

[A]

Right. And that is how we get to the point now where the ozone layer is doing well. It's the, I read it's the fifth smallest since the crisis. Why hasn't the ozone fully thickened over Antarctica? Is it because people are still using chemicals even though they're banned?

[B]

Some chemicals actually can leave once they get into stratosphere. They can live up to 100 years. So once they release, let's say they've been released in the 50s and even before that they have quite a long way to go before they get completely removed from the stratosphere. So that the ozone hole is recovering, but you know, very slowly because we still have a lot of these chemicals in the atmosphere still.

[A]

And to this day people are still monitoring the ozone layer. Right. Like we didn't fix the problem and just abandon the Antarctica. Right.

[B]

No, we are very lucky. We still have a lot of observations. So yes, I mean we still need to monitor it. And the reason for that is that there are some other chemicals that been released atmosphere, they're not really destroying ozone. They are replacement for those CFCs. We need to know how they're impacting the atmosphere. And some of them are so called greenhouse gases. So they're heating the atmosphere. And with that there is also some impact on the way how the ozone is recovering.

[A]

Yeah, Greenhouse gas emissions. We talk about that a lot on shortwave. And it's a useful comparison because that existential issue is also human caused and could be human solved, so to speak. So in comparison to climate change that we're all struggling with now, why do you think the ozone issue was dealt with so swiftly?

[B]

I think because that was a problem affecting everybody.

[A]

Yeah.

[B]

It wasn't something that would require people to stop using, for example, you know, that people were advised not to use aerosols, for example, by scientists. But it was, wasn't a very big impact on everybody's Life.

[A]

Giving up CFCs was a lot easier than giving up like oil and gas.

[B]

Yes, yes, I think that was one condition. And then of course, you know, the industry also agreed to change and move away from the CFCs and start producing other chemicals that are not destroying ozone. And not just that. The developed countries also said that they will set aside the finding for supporting and helping the developing countries to change the technology and so that that still continues.

[A]

How does that make you feel as a researcher that humanity scientists working with policymakers, working with many stakeholders were able to do this? How do you feel about that?

[B]

I'm really excited about that and we were very young when we started to hear about ozone in my generation and it was very acute problem. And it's just really good to see that ozone is on the way to recovery. It's in the 2050s, 60s, you know, when people expect the full recovery of the ozone. But you know, who knows, maybe I will live too long enough to see that.

[A]

I hope you do. I hope I do. Irina, thank you so much for coming on shorewave.

[B]

Oh, thank you so much for taking time.

[A]

If you liked this episode, follow us on the NPR app or wherever else you listen to podcasts and check out our episode about how tourists are solving a plankton puzzle in Antarctica and Shortwave's Nature Quest series. That's where we delve into an environmental mystery driven by your questions. I'm Emily Kwong. Thanks for listening and tune in tomorrow for.

[C]

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