Massive hole in ozone layer

Things to think about

1. Before viewing

Why is exposure to UV radiation from sunlight so dangerous? What can you do to protect yourself from its effect on your body?

2. As you view

In 1975, Dr Jon Shanklin published a surprising discovery about the ozone layer over Antarctica. What was it?

What are CFCs? What were they used for? Why are CFCs so dangerous?

How is the world's response to damage to the ozone layer after 1985 presented here?

How does Dr Paul Fraser view the long-term recovery of the ozone layer?

3. After viewing

CFCs are described as catalysts. What is a catalyst and how does it work?

Why has it been taking so long for the ozone layer to recover since CFCs were banned?

What would your daily life be like in 2050 if action hadn't been taken to protect the ozone layer?

4. Next steps

Consider how the story of damage to the ozone layer is linked to climate change and the debate around action.

Source: Catalyst | Learning area: Science | Secondary: Year 10


Imagine life on Earth without the protective ozone layer in the atmosphere absorbing dangerous UV rays. Scientists predicted that this would be the scenario by 2060 if nothing was done to reduce CFC emissions. But this is a good news story: in 1987, by agreeing to implement the Montreal Protocol that limited CFC emissions, the world chose a different future. Watch as scientists show how the ozone hole was discovered and listen as they describe how a serious challenge to life on Earth was averted.


00:00:00:00MARK HORSTMAN:A good news story about how we've saved the world.

...Read more >

00:00:05:19NARRATOR:But for a long time, it seemed the end of the world was nigh. More than 15 kilometres high in the stratosphere, the ozone layer forms a natural sunscreen, protecting life on earth. But when rogue chlorine atoms from synthetic gases are let loose up there, they act as catalysts to pull apart the triple oxygen molecules of ozone.00:00:32:00FEMALE NEWSREADER:Ozone depletion in the atmosphere is getting worse.00:00:37:06NARRATOR:Since 1975, science knew that increasing the use of synthetic gases like chlorofluorocarbons or even the exhaust of high-flying Concordes, could degrade the ozone layer.00:00:50:08MALE NEWSREADER:Those inert little molecules from spray cans or airconditioners may present a greater threat than a whole brace of nuclear missiles.00:00:59:10NARRATOR:The world was alarmed, but there was little evidence to show the threat was real. Until 1985, that is, when a startling report was published in Nature. Meteorologist Jonathan Shanklin had been working in Antarctica to measure ozone levels above the Halley Research Station with this Dobson spectrophotometer.00:01:24:23JON SHANKLIN:I thought it would be helpful to show people this ozone data and compare it with 20 years earlier, and it would be the same. Only trouble was that in the springtime it wasn't.00:01:40:06NARRATOR:That may be the understatement of the century. John and his colleagues had discovered a gaping bite out of the ozone layer above Antarctica.00:01:50:19JON SHANKLIN:We were completely gobsmacked, as they we saw this because it wasn't expected. What we were able to show was that it was a systematic decrease by 30% to 40% - quite a dramatic change and far outside anything that had been seen in the total record that we've got.00:02:15:21NARRATOR:During that same period, from the mid-'70s to the mid-'80s, Paul Fraser was recording a steady increase in levels of ozone-depleting gases.00:02:26:18PAUL FRASER:When the Shanklin paper was published, a whole new field of chemistry opened up because no-one had considered that the special conditions in Antarctica would generate this extremely powerful mechanism for ozone destruction.00:02:41:10JON SHANKLIN:So, what on earth was going on? During the winter, the Antarctic ozone layer gets cold enough that clouds actually form in the middle of the ozone layer, and it's chemical reactions on the surface of those clouds that allow, in the spring, very efficient reactions to take place that destroy the ozone.00:03:04:05PAUL FRASER:That was a clear demonstration that an industrially released chemical, in minute amounts, relatively speaking, was having a massive effect on a major atmospheric constituent, and it was unprecedented.00:03:19:15NARRATOR:Around the world, governments were galvanised into action.00:03:24:06PAUL FRASER:By 1987 we had a Montreal Protocol. By 1990, CFCs were on the path to not being used anywhere. And by the late '90s they were gone. And all we're left now is the residue of what we put into the atmosphere 30 years ago.00:03:47:06MARK HORSTMAN:The air I'm breathing here comes straight off a vast ocean direct from Antarctica. Now, there's just a handful of places in the world where the air is so clean that you can measure minute changes in the composition of the atmosphere, and this is one of them - the Cape Grim Monitoring Station in north-western Tasmania.00:04:07:21NARRATOR:If something's detected in the air here, that's strong evidence it's everywhere. Since the 1970s it's become the most important station in the Southern Hemisphere, and for the ozone layer, the outlook is good.00:04:25:03PAUL FRASER:Overall there's been a significant net decline in what we call effective chlorine, and that's what drives ozone depletion. We are expecting to see an ozone recovery, but these CFCs are very persistent in the atmosphere. The atmosphere will remove them, but it takes hundreds of years, and so the long-term recovery of ozone is a slow process. We probably expect to see ozone recovery about 2060.00:04:53:23NARRATOR:On the left is the world we're living with. On the right is the world where CFCs weren't banned. Low ozone concentrations are in blue, average in green.00:05:07:08PAUL NEWMAN:If you let chlorofluorocarbons increase by 3% each year, starting in 1974, by the year 2065, virtually two-thirds of the ozone layer has been destroyed.00:05:20:08NARRATOR:That's not just over the poles, but everywhere. The Antarctic ozone hole becomes a permanent year-round fixture with a twin over the North Pole. In the 2050s, something very scary happens in the modelled world - ozone levels over the tropics collapse to near zero. Levels of UV radiation triple.00:05:46:13PAUL NEWMAN:And UV radiation is used to sterilise things. If we'd never regulated CFCs you wouldn't have been able to go outside for much time at all.00:05:59:07PAUL FRASER:Occasionally I think about what happened if things had gone wrong and we weren't able to carry the popular view and, you know, people just said, "Oh, you know, this is nonsense. We wanna keep our CFCs," for example. I don't know. It'd It'd be certainly a serious health issue.00:06:19:17NARRATOR:And here's the twist that links this story to the current debate about climate change. Ozone-depleting gases are extremely powerful greenhouse gases as well.00:06:32:20JON SHANKLIN:By limiting them through the Montreal Protocol it's actually done more than the Kyoto Protocol did to limit the growth of greenhouse gases in the atmosphere.00:06:45:00PAUL FRASER:I would say it's somewhere between 5% and 10% less greenhouse gas warming than there would have been because of the Montreal Protocol.00:06:55:02MARK HORSTMAN:When doubts are raised about whether international agreements like the Kyoto Protocol can reduce industrial emissions in time to save us from the atmosphere, remember - it's been done before.00:07:06:16JON SHANKLIN:We went from the ozone layer being perfectly OK to 50% gone in the space of a decade. And that surely sends us a warning that we can change our planet very quickly without intending to do so.

For teachers

  • Science: Year 10
  • Strand: Science Understanding
  • Substrand: Earth and space sciences
  • Content code: ACSSU189
  • Science: Year 10
  • Strand: Science as a Human Endeavour
  • Substrand: Nature and development of science
  • Content code: ACSHE192
  • Content description: Advances in scientific understanding often rely on developments in technology and technological advances are often linked to scientific discoveries

About this resource



Date first broadcast:

08 May 2010

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Massive hole in ozone layer