National Geographic News
The ozone hole on September 25, 2009.

Satellite data show the Antarctic ozone hole as it appeared last fall.

Image courtesy NASA

Brian Handwerk

for National Geographic News

Published May 5, 2010

What would the 1980s have been without big hair and ice-cold wine coolers?

Luckily no one had to find out: Key substitutions in hairsprays and refrigerants allowed such products to exist without chlorofluorocarbons (CFCs), which were found to be ripping a huge "hole" in Earth's protective ozone layer.

Today the ozone hole, which was first spotted 25 years ago, appears headed for a happy ending, thanks to unprecedented international action.

Could a similar effort rein in climate change? And is the closing ozone hole actually making global warming worse?

Ozone at High Risk From CFCs

The ozone layer lies between about 9.3 and 18.6 miles (15 and 30 kilometers) above Earth's surface. This blanket of ozone, or O3, blocks most of the sun's high-frequency ultraviolet rays.

These UV rays can cause skin cancer and cataracts in humans, as well as reproductive problems in fish, crabs, frogs, and even in the single-celled phytoplankton at the bottom of the ocean food chain.

Ozone is created naturally when oxygen molecules (O2) high in the atmosphere get broken by sunlight into two free oxygen atoms. A free atom can then bond with an unbroken O2 molecule, and ozone is born.

Ozone is unstable, however, and it's easily broken up by trace elements.

Invented in the 1920s, CFCs proved to be an exceptional problem for ozone, because many of these synthetic chemicals can persist for decades, allowing them to make their way into the upper atmosphere. (Related: "Rocket Launches Damage Ozone Layer, Study Says.")

In that rarefied air, ultraviolet light breaks the molecular bonds in CFCs and free chlorine atoms get released. Chlorine then destroys ozone molecules by "stealing" their oxygen atoms.

Ozone Hole a Shocking Surprise

Scientists had theorized since the 1970s about the chemistry that could lead to ozone depletion. But in May 1985 scientists with the British Antarctic Survey shocked the world when they announced the discovery of a huge hole in the ozone layer over Antarctica.

Technically a substantial thinning of the ozone layer, the ozone "hole" has been opening every spring since the 1970s, the scientists reported.

Their data, collected at the Halley Research Station in Antarctica, suggested that CFCs were to blame. That's because atmospheric conditions during the cold, dark, Antarctic winters were building stockpiles of CFCs over the South Pole.

Returning spring sunshine would then spawn an abundance of free chlorine, depleting ozone levels above Antarctica by as much as 65 percent. (Related: "Laughing Gas Biggest Threat to Ozone Layer, Study Says.")

"One lesson is that the planet can change very rapidly in an unexpected way," said Jonathan Shanklin, one of the British scientists who made the ozone hole discovery and co-author of a paper on the ozone hole anniversary appearing in this week's issue of the journal Nature.

"Nobody was expecting to see anything like this in the Antarctic."

Fixing the Ozone Hole a Unanimous Decision

The disturbing discovery set the stage for an environmental triumph: the Montreal Protocol of 1987.

This pact to phase out the use of CFCs and restore the ozone layer was eventually signed by every country in the United Nations—the first UN treaty to achieve universal ratification.

The unparalleled cooperation has had a major impact.

"If we had just kept letting CFCs increase at a pretty nominal rate, characteristic of the 1970s, the decreased ozone levels of the hole would have eventually covered the entire planet," said atmospheric physicist Paul Newman of NASA's Goddard Space Flight Center.

"Global ozone dropped a little bit [after CFCs were banned], but the good news is that if we had done nothing, it would have gotten really, really bad."

Now a complete rebound seems imminent. Some scientists project that by 2080 global ozone will return to 1950s levels.

(Related: "Old Fridges, Cars Slow Ozone Hole Recovery, Scientists Say.")

Now How About Global Warming?

As climate scientists around the globe urge action to curb greenhouse gas emissions, might the ozone hole experience provide some useful parallels? Perhaps, experts say—but the situations do have some significant differences.

In the 1980s people were faced with the clear and present health dangers from ozone depletion, leading to widespread public support for CFC bans.

"There was a scary side of the ozone hole, linked to skin cancers and cataracts and so on, which immediately engaged the public," the British Antarctic Survey's Shanklin said. "The real impact of what a rapidly warming world could do is not so obviously intuitive."

Chemical manufacturers were also able to create substitutes for CFCs with little added costs, enabling governments to address the problem without great impacts on the economy or average lifestyle.

Global warming, on the other hand, has become a politically loaded and often divisive topic.

And many potential fixes to the problem—such as alternative energies and reduced consumption—could cause major disruptions to economic and geopolitical norms in a way that replacing CFCs simply did not, Shanklin said.

Ozone Recovery to Warm Antarctica?

Meanwhile, some scientists say the environmental triumph of a recovering ozone layer could have a troubling side effect: boosting global warming, at least in the Antarctic region.

Ozone itself is a greenhouse gas. A thinner ozone layer not only reduced heat trapped over the region, it helped stir circumpolar winds, which in turn created sea spray that formed reflective, cooling clouds.

"It's very difficult to quantify the impact on a global scale, but I think the evidence suggests filling the hole will have a regional effect on the Antarctic, possibly leading to more warming for the bulk of the Antarctic," Shanklin said. "That could drastically change predictions about global sea level change."

Ken Carslaw of the U.K.'s University of Leeds was a co-author on the study that suggested closing the ozone hole would lead to a bump in Antarctic warming. Still, he thinks that any warming mitigation produced by the ozone hole was merely a side effect and not a net gain.

"I wouldn't say that these discoveries [of possible warming] suggest the formation of the ozone hole was a good thing," he said.

NASA's Newman agreed: "The consequences of unabated CFC growth were disastrous for life," he said.

"So at some point you had to act, and fortunately they acted before it became a really severe problem. We never got to the level of an environmental catastrophe.

"It really is a testament to the good science that went into [understanding] the ozone hole and the nerve of the politicians to act on that science."

dev dongol
dev dongol

First prove gases cause global warming. Can you?

Ozone as such can't exist as a layer. It is extremely unstable. It breaks into oxygen atoms as soon as it forms. It is formed when oxygen molecules breaks into atoms with heat of high temperature (UV).
Stratosphere is extremely cold zone and low pressure. Ozone formed breaks down
 as soon as it forms to release heat. Even at sea level at NTP ozone is unstable.
So ozone layer exists only in theory. Intermittently forming of ozone will continue
until the oxygen is in the atmosphere and we receive UV from the sun. So ozone depletion is not possible.

So what?  let us first have water for every body and every where!
by developing water supply networks. Moisture content on land surface controls our climate. No dry part on the land surface of the earth! Nature will take care rest. We are expanding more and more dry land surface by urbanization, deforestation and deserts formation  causing climate change and power crisis.

It is possible to run turbines in series without decreasing their  efficiency. Running turbines does not decrease the power of running water, it remains constant.
 CC is real. It is reversible. We can control Climate, since we are chaNGING.
 Man-made not gas-made. For solution to power crisis and climate change
visit my blog for details

GH gas theory is ridiculous, imaginary, false, spurious and so on.
Gases can't form green house. So green house effect due to gases is impossible.
 They are actually helping the earth to cool down by convection method of
heat transmission. Gases have freely moving molecules, so you can't fix any fluid
to make a structure. CAN YOU??  Shame on you IPCC / NASA !!!!dev bahadur dongol

jenna avery
jenna avery

So now they want to say that because they singed a UN treaty. ( BIG POWER GRAB) (takes U.S. sovereignty away) That our ozone is really repairing itself thanks to that. SURE! I believe it. THE AUDACITY!  Ok now that they get disproven the ozone hole is now closing now they say oh yes our signing of this treaty has fixed this issue. P-L-ease! What next? Is their global warming theory going to be disproven as well. I understand there is real global warming not caused by us but by nature. What will they come up with next when they are proven wrong again? LOL they will take credit yet again and continue lying to the public.

jenna avery
jenna avery

Hahaha! YEA RIGHT!!  Can we be THAT stupid to believe this propaganda? What an insult to our intelligence. This is just what we will keep getting and what we have been getting through our "education" system. Our brainwashing that we get since we are kids we still get it in the mainstream media. 

Kim Matthews
Kim Matthews

What a load of rubbish!!! The holes in the ozone at the poles occur naturally. Volcanoes are more of a threat to the ozone layer than humans ever could be. So tired of bad science being punted as good.

Finnian McEvoy
Finnian McEvoy

@brant callahan

UV breakes up CFCs into Cl* radicals:

CF2Cl2 -> CF2Cl* + Cl*

Cl* radicals break up Ozone

O3 + Cl* -> ClO* + O2

ClO* + O -> Cl* + O2

This repeats until radicals are paired up again. This may never happen and the Cl* could destroy billions of O3 molecules.

O3 is Ozone unless you didn't get that.

Finnian McEvoy
Finnian McEvoy

@jenna avery Wow you seem to be an expert on Ozone depletion, unlike me; a foolish chemist. I would love to see the evidence you have accumulated to support your argument. I have been blinded by these false sources that I read; lies from NASA, The Met office, NOAA, and National Geographic, all of them sophistic slippery rabble-rousers! I would love to be enlightened by you Jenna as I too am a supporter of US Sovereignty after all; what is the point in having a HABITABLE planet if the USA is not in charge?

Jay Clemons
Jay Clemons

@jenna avery  - The SHEER, PROUD IGNORANCE! The science of ozone depletion is about as sound as science gets; the hole was predicted before it was found! (See the article..) Thank heaven for the international agreement (Montreal Protocol) to address this crisis; would that more "sovereignty" (of countries to act in their own "self interest" to the detriment of the rest of the ecosphere) could be taken away! 

Well, at least you admit there IS real global warming. Of course, just about every climate scientist disagrees with you about the cause. I'm having trouble imagining how they could all be wrong, while you are right based on no evidence or knowledge. HMMM..

Diana Harding
Diana Harding

@jenna avery  As a scientist and an educator I have always found public education in the sciences in my state to be top notch. No "propaganda"  or "brainwashing" involved. Apparently you have been affected by pseudo science or just plain bad science used by some political/religious/industrial factions in the US. When you make your statements, you will need to back it up with citations from trusted scientific sites. Please do so in the future. We find it hard to take you seriously when you do not do this.

Finnian McEvoy
Finnian McEvoy

@jenna avery It certainly is EVIL of those teachers! To, to educate our helpless children to care for the planet and their fellow humans above making money. And It is terrible that they are literally being told that they CAN do something to help! 

How disgraceful! 

Bryson Bunn
Bryson Bunn

@jenna avery  Ive been learning about this and its not a laughing matter so please with all due respect SHUT UP

Diana Harding
Diana Harding

@Kim Matthews When you make your statements, you will need to back it up with citations from trusted scientific sites. Please do so in the future. We find it hard to take you seriously when you do not do this. If volcanoes are more of a threat to the ozone layer, then you shoes be able to easily back up your statement with valid scientific data.

Heather Matthies
Heather Matthies

@Kim Matthews I suppose your degrees in science brought you to that conclusion or is it your lack of degrees that got you there???

jenna avery
jenna avery


Are you talking about this non sense article?

Jim Thompson
Jim Thompson

@MUS LUKMANI @Kim Matthews Volcanoes release more than 130 million tonnes of CO2 into the atmosphere every year. SO2 effects Earth's surface temperature Global cooling and ozone depletion

Measurements from recent eruptions such as Mount St. Helens, Washington (1980), El Chichon, Mexico (1982), and Mount Pinatubo, Philippines (1991), clearly show the importance of sulfur aerosols in modifying climate, warming the stratosphere, and cooling the troposphere. Research has also shown that the liquid drops of sulfuric acid promote the destruction of the Earth's ozone layer.

Please see the web article, "Volcanic Gases and Climate Change Overview" for additional information.

M er
M er

@Jay Clemons @jenna avery  

I alway advise my children that only those with weak positions default to calling names.

Is this a practice you learned while earning your "degrees in science"?

Seems you "opened your mouth."

This was my first time on the site and it is a grave disappointment that the discussion falls to this.

This will be my last time on the site. 


Jay Clemons
Jay Clemons

@jenna avery  I think you are unclear on the meaning of the word "nonsense".  The article is well written, and makes perfect sense. Mus Lukmani was talking about the nonsense COMMENT posted by a breathtakingly uninformed troll. Try to remember: better to remain silent and risk being thought a fool than to open your mouth and remove all doubt..

Austin Thomas
Austin Thomas

@Jim Thompson @MUS LUKMANI @Kim Matthews  Maybe if you bothered researching a tad more, you'd find that most of the expulsions of volcanic eruptions are harmlessly rained out of the atmosphere since the products are water soluble. Yes, some ozone depletion occurs naturally, and yes, CFCs are another known cause, probably not on such a scale we measure it to be causing. HOWEVER, volcanic eruptions have been occurring for millions of years, and common sense would entail that it hasn't caused that dire of a change for as long as it's been going on. I do agree that some chemicals released during an eruption would cause depletion of the ozone layer, and some even go as far as to reach the ozone within a period of time, but most of them, as stated before, are rained out of the atmosphere because of their solubility. 

Finnian McEvoy
Finnian McEvoy

@brant callahan @Jay Clemons @jenna avery Ok guys look, the article is about CFCs the Ozone and our response to the crisis. Chlorine radicals, released by the breakdown of CFCs DO destroy Ozone. FACT. It is not like one Cl radical breaks down one Ozone molecule, no, the process can be indefinite.

It is obvious that CFCs can and have broken down the Ozone layer to some extent. Banning them WAS an important and necessary move. If it had not been done, the ozone layer would have eventually been totally destroyed and we would all go blind and die from skin cancer.



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