Ozone layer is on track to fully repair itself by the 2060s

Co-ordinated, global action in 1980s staved off catastrophe

Today's expression: Thin out
Explore more: Lesson #564
April 17, 2023:

The ozone layer, a part of the stratosphere that deflects the sun's harmful UV rays, was in danger of disappearing due to industrial and consumer chemicals. But a global treaty signed in Montreal reversed the damage. Now, a new report says the ozone layer is on track to fully repair itself by the 2060s. Plus, learn the English expression "thin out."

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Here’s a real environmental success story: the ozone layer is repairing itself

Lesson summary

Hi there everyone, I’m Jeff and this is Plain English, where we help English learners around the world—and it really is around the world, it’s like 160 countries where we have listeners—we help you upgrade your English skills with current events, trending topics, and common English expressions.

Today is lesson number 564. So if this is your first time listening, you are in for a treat. There are 563 other Plain English lessons that you can listen to. But this one is already online at PlainEnglish.com/564. JR is the producer; he’s the one that uploads all the great content to the web site for you each and every Monday and Thursday.

Coming up today: The ozone layer is on track to be completely repaired by the 2060s, according to a report earlier this year by the United Nations. When I was a kid, the ozone layer was the number one environmental topic of the day. And a remarkable worldwide effort to slow the damage to the ozone layer has been successful, at least according to the latest modeling.

In the second half of today’s lesson, I’ll show you how to use the English phrasal verb “thin out.” This is a hard one, so pay close attention during the lesson to see if you can understand the meaning. Let’s dive in.

Ozone layer on path to completely heal by 2060s

Ultraviolet-B rays, or UV-B rays, from the sun cause sunburns and cancer in humans and can kill plant and animal life. Luckily, the Earth’s atmosphere deflects the majority of the sun’s UV-B rays, and the sun’s rays don’t harm us—as long as we don’t stay in the sun for too long.

But for a time in the 1980s and 1990s, it appeared that the part of the atmosphere that protects us from the sun was depleting at an alarming pace. Scientists warned at the time that it could be gone entirely by the 2060s.

That part of the atmosphere is called the ozone layer. It’s between 15 and 50 kilometers above the Earth’s surface. The oxygen you breathe is O-2: two atoms of oxygen bound together. Ozone is just a little different: it’s O-3.

Scientists have monitored the ozone layer for a long time. And in the early 1980s, they discovered that the ozone in the stratosphere was thinning out over the poles, Antarctica and the Arctic Circle. They also knew the culprit: industrial chemicals called chlorofluorocarbons, or CFC’s. These were common in refrigerators, industrial processes, and aerosol sprays.

CFC’s contain chlorine. And what happened was this: the CFC’s released near the Earth’s surface eventually rose into the stratosphere. Once there, the chlorine in CFC’s reacted with the ozone. In this reaction, the O-3 ozone broke apart. One chlorine atom fused with one oxygen atom, forming chlorine monoxide. And the remaining two oxygen atoms formed O-2, the oxygen we breathe.

So the more CFC’s that were released into the atmosphere, the more the O-3 ozone broke apart. But that’s not all. Remember that chlorine from CFC’s reacted with the O-3 to become chlorine monoxide. Well, eventually guess what: the chlorine monoxide broke apart, freeing that same chlorine atom to react with even more ozone and repeat the process.

And then , something happened that seems impossible today: almost the whole world got together to solve the problem.

In 1986, the United Nations began work on an international treaty that would ban CFCs. The treaty eventually became the Montreal Protocol on Substances that Deplete the Ozone Layer; that’s a mouthful, so we’ll call it the Montreal Protocol. One hundred ninety-seven countries signed the international treaty, which identified over 100 substances that would be banned.

They included Freon, which was the chemical that made your refrigerator work. Freon was also found in dehumidifiers, ice machines, water coolers, and vehicles. That’s not all: a lot of aerosol sprays like hairspray and deodorant had CFC’s. So did insulation, packing material, and fire extinguishers.

Transitioning away from CFCs was a costly and long process. But the Montreal Protocol included assistance for developing countries. The treaty recognized that stopping the release of CFC’s was a global responsibility. But it would be harder for poorer countries to make the transition. So the treaty provided economic assistance to developing countries to make the transition.

Fortunately, there were already alternatives to almost all CFC’s: it wasn’t a question of giving up a products or technologies, but rather of making them in new, albeit more expensive, ways. Freon, for example, was the CFC used in refrigerators and air conditioners. New machines were made with Puron, a hydrocarbon refrigerant that doesn’t contain chlorine. But that didn’t mean that CFC’s were phased out overnight .

The average life of a refrigerator, of a truck, of an ice maker, could be decades. So while new refrigerators were made with Puron, the old Freon machines were still in use. Even today, some old machines still use Freon.

The good news, though, is that a new United Nations report shows that the ozone layer is repairing itself. The study showed that the ozone layer will be fully recovered in four decades from now—by the 2060s. It said that the global average will return to its 1980 state by the year 2040, and that the ozone layers by the poles will recover by 2066.

This is a success. The Montreal Protocol is often considered the most effective international treaty ever signed. One estimate says that the world’s action in Montreal will save half a billion cases of skin cancer. Another says that worldwide warming would have been 1 degree Celsius higher by 2050 without Montreal.

Refreshed Instagram

I mentioned last week that we refreshed our Instagram account . I’d love to see you there on Instagram, if you’re on that platform. Follow us @plainenglishpod and we’ll brighten up your feed.

If you use Instagram for English learning, you can “favorite” posts that you want to review later. Some of our posts are about the expressions we talk about here. So if you hear one and you need a reminder, or you want to practice it later, just click the bookmark icon and you’ll be able to go back and look at it later.

That works for other accounts, too, not just for Plain English. So if you follow English learning accounts, just click that bookmark for posts you want to review later.

@plainenglishpod is how you’ll find us on Instagram—and I check all the messages, too, every day, so feel free to tag us on your posts or send a DM.

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Expression: Thin out