Support for NPR and the following message come from the William and Flora Hewlett Foundation. Investing in creative thinkers and problem solvers who help people, communities, and the planet flourish. More information is available at Hewlett.org. 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. Without ozone, that would be impossible to live on earth. 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. 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. 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. Scientists notice 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 that was happening in the springtime in Antarctica. And so they noticed that there was less ozone. A giant hole is forming in the earth's protective ozone layer. Scientists discovered a hole in this protective ozone. A remarkable loss 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. This message comes from WISE, the app for international people using money around the globe. You can send, spend and receive in up to 40 currencies with only a few simple taps. Be smart, get WISE. Download the WISE app today or visit WISE.com. Tease and seize, apply. Support for NPR and the following message come from the William and Flora Hewlett Foundation. Investing in creative thinkers and problem solvers who help people, communities and the planet flourish. More information is available at Hewlett.org. So Irina, I want to focus on how the ozone is operating over Antarctica, because that's where the hole is. And I know that the ozone layer over Antarctica naturally fins, because things are a little different there, right? 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's no much of the ozone production happening during the winter time. 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. 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 when the air from other parts of the world that have access to sunlight mix with Antarctica's air? Antarctica has a very specific process, because it's a continent, the atmosphere can create the strong winds that circulate around Antarctica. And so they separate the air that's over Antarctica from the rest of the other lighted tubes outside of Antarctic vortex. So there is no really way to mix it with other airflow. Oh, okay. So the atmosphere of Antarctica is isolated because of this polar vortex, which results in the 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? 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 chlorine, the chemicals that they thought 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 a very good sense to them, so that those chemicals are destroying ozone. It's like their Achilles' heel. I read that one chlorine atom can destroy over 100,000 ozone molecules. Yeah, definitely. What the heck were we doing in the 50s and 60s that created this abundance of chemicals in the atmosphere? 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. But I'm curious, 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? Well, the atmosphere has this mixing properties. You know, there are a lot of exchange between the troposphere and stratosphere and the tropics. And they can travel also with this flow of the air from the tropics into the middle latitudes in the polar regions. There is the so-called Brie-Rdupsten circulation in the atmosphere. And they get distributed everywhere. So they hang out a long time. 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. They're called the polar stratosphere clouds. Solar stratospheric clouds. 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 polar stratosphere clouds that typically neutralize these reactions. And so there is nothing to stop those chemicals to destroy ozone for some period of time until the polar stratosphere clouds disappear. 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? Right, exactly. So they started to present their findings to the public, to the governments. And so eventually, they got enough people to listen 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. I agreed to stop production and use of those ozone-depleted substances. 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? Some chemicals actually can leave once they get into stratosphere. They can leave up to 100 years. So once they release, let's say they've been released in the 50s and even before that, they have a quite long way to go before they get completely removed from the stratosphere. So that the ozone hole is recovering, but very slowly because we still have a lot of these chemicals in the atmosphere still. And to this day, people are still monitoring the ozone layer, right? Like we didn't fix the problem and just abandoned the Antarctica, right? 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 in the atmosphere. They're not really destroying ozone, they're replacement for those CFCs. We need to know how they impact in 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. 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? I think because that was a problem affecting everybody. Yeah. It wasn't something that would require people to stop using, for example, you know, that people were advised not to use their soils, for example, by scientists. But it wasn't a very big impact on everybody's life. Giving up CFCs was a lot easier than giving up like oil and gas. Yes. I think that was one condition. And then, of course, 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, 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's still continuous. 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? I'm really excited about that. And we were very young when we started to hear about the ozone in my generation. And it was very a cute problem. And it's just really good to see that ozone is on the way to recovery. It's in the 2050, 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. I hope you do. I hope I do. Idena, thank you so much for coming on Charwaive. Oh, thank you so much for taking time. 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 more. So support for NPR and the following message come from the William and Flora Hewlett Foundation, investing in creative thinkers and problem solvers who help people, communities and the planet flourish. More information is available at Hewlett.org.
