NASA-funded Network Tracks the Recent Rise and Fall of Ozone Depleting Pollutants


Feb 17, 2021

A short-lived resurgence in the emission of ozone depleting pollutants in eastern China will not significantly delay the recovery of Earth’s protective “sunscreen” layer, according to new research published Feb. 10 in Nature.

Stratospheric ozone, also known as Earth’s ozone layer, helps shield us from the Sun’s harmful Ultraviolet (UV) rays. Compounds like CFC-11 (Trichlorofluoromethane, also known as Freon-11), a chemical once considered safe and widely used as a refrigerant and in the production of insulation for buildings, rise to the stratosphere after emission on Earth’s surface. Once in the atmosphere, CFC’s are broken down by the UV light and result in the destruction of ozone molecules, both reducing stratospheric ozone concentrations globally and contributing to a “hole” in the layer that appears over Antarctica in the spring.

NASA computer models help scientists identify an uptick in atmospheric emissions of an ozone-depleting gas called CFC-11. NASA and the National Oceanic and Atmospheric Administration (NOAA) work together as part of a long-running research partnership to monitor emissions of stratospheric ozone and to support ozone scientists at MIT and the University of Bristol.
Credits: NASA’s Goddard Space Flight Center
Download this video in HD formats from NASA Goddard’s Scientific Visualization Studio

In 1987, the Montreal Protocol – an international treaty enacted to protect the ozone layer from additional degradation – banned new production and trade of ozone depleting substances like CFC-11. One hundred ninety-eight nations have since signed on to the agreement.

After production ceased, scientists still expected CFC-11 to continue leaking over the years from existing products, but at a gradually declining rate. Because of this, the gas is among those monitored at the global scale by the National Oceanic and Atmospheric Administration (NOAA)’s Global Monitoring Division and the Advanced Global Atmospheric Gases Experiment (AGAGE) – a network of monitoring stations funded by NASA and several environmental agencies, and headed by the Center for Global Change Science at the Massachusetts Institute of Technology and the Scripps Institute of Oceanography. 

In 2018, NOAA first reported a smaller decrease in the decline of atmospheric CFC-11 than expected. The numbers didn’t align with trajectories based on CFC-11’s production ban, hinting that something had changed. “The slow-down in the rate of decline indicated that somebody was emitting again, or in larger quantities than we were expecting, we just didn’t know where,” says Matt Rigby, University of Bristol (UK) scientist and one of the lead authors of the new study.

It was the AGAGE network that helped track down the origins of much of the new emission of CFC-11 thanks to its geographic distribution. Two of its stations, the South Korean Gosan AGAGE station, run by Kyungpook National University in South Korea, and the AGAGE-affiliated station on Hateruma Island in Japan, run by Japan’s National Institute of Environmental Studies, were both positioned close enough to the source for researchers to track much of the new emissions back to their source: eastern China. 

“This is very much like detective work,” said Qing Liang, a research scientist at NASA Goddard’s Space Flight Center in Greenbelt, Md. and co-author of the study. “We figured out there was a problem, then we tracked down where the problem was regionally, and it seems that the actions taken in China, and perhaps elsewhere, have resulted in a big drop in the unexpected emissions [since 2018].”

Due in large part to effective monitoring, and subsequent reaction to the 2018 report, data and analysis in these two papers (published in February 2021) suggest that both the renewed eastern Chinese and overall global emissions of CFC-11 after mandated global phase out in 2010, have returned to previous levels.

A map of stations showing the increase in CFC-11 emissions and the drop that followed their detection.

Two AGAGE stations, one in South Korea and one in Japan, captured the increase in CFC-11 emissions from eastern China and the drop in emissions that followed their detection.Credits: NASA Earth Observatory/ Joshua Stevens

Not only is this important for the ozone layer’s recovery, but CFC-11 also impacts climate as a potent greenhouse gas. The observed levels of increased emission were comparable to the carbon dioxide emissions of a city roughly the size of London. In other words, closing off CFC-11 emissions has an additional climate benefit similar to that of shutting off a megacity.

Despite the monitoring success story, some emissions are still unaccounted for – and scientists have been unable to pinpoint where they are coming from due to current limitations of the monitoring network.

“The one critical piece of information we need is atmospheric observations,” said Liang. “That’s the reason why it is really important for NASA and NOAA, together with their international partners, to continue making measurements of these gases.” Monitoring networks like the AGAGE stations are a valuable tool for understanding the role atmospheric chemistry plays in our changing climate.

Though these new CFC-11 emissions were identified relatively quickly, they have the potential to delay ozone layer recovery, especially if left unchecked, so a timely response is paramount.

“This was evidence for probably the biggest challenge that the Montreal Protocol has ever faced,” said Rigby, “but I think it’s been heartening to see how closely the science has been listened to by the parties of the Montreal Protocol, and then how rapidly the science has been acted on as well; All this has happened over the space of essentially two years, which is pretty incredible.”

Banner image caption: Pollution hanging over eastern China in February of 2004. Credits: Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE.

By Lara Streiff

NASA’s Goddard Space Flight Center, Greenbelt, Md.Last Updated: Feb 17, 2021Editor: Sofie Bates

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Mark Pawelek
February 19, 2021 2:08 am

This article is nonsense. The hole in the ozone is in the SH, not the NH. If CFCs cause holes in the Ozone, they ought to be able to show correlations. Where are those studies?

All they have are dodgy models. Models proved wrong again and again.

Jon-Anders Grannes
Reply to  Mark Pawelek
February 19, 2021 5:22 am

Another false consciousness caused by propaganda, brainwashing and policybased science?

Last edited 9 days ago by Jon-Anders Grannes
Richard Page
Reply to  Mark Pawelek
February 19, 2021 11:36 am

Firstly they aren’t really holes – they are areas where the ozone layer is thinner than anywhere else. Secondly there are areas of thinning over both Antarctica and the Arctic regions. Hope that helps to clear things up!

Reply to  Richard Page
February 20, 2021 6:38 am

Your assertion does not “clear up” anything.

Peter F Gill
February 19, 2021 2:23 am

My understanding is that blaming CFCs for ozone depletion (Rowland’s hypothesis) was unfounded for a number of reasons (given by Dr Edward Krug) not least that the mechanism could not be replicated in a laboratory or detected in the atmosphere. I recall that Al Gore fired Dr William Happer in 1993 just for suggesting that the ultraviolet monitoring program cancelled in 1985 should be refunded. As regards dodgy mechanisms I am reminded of both the acid rain story and the current AGW nonsense.

Reply to  Peter F Gill
February 19, 2021 4:26 am

Didn’t Fred Singer tell us, that CFC only in connection with cosmic rays are able to have an effect on ozone ?
Not that he found it but always pointed on these findings.


Last edited 9 days ago by Krishna Gans
Reply to  Peter F Gill
February 19, 2021 5:18 am

Your comment on the “acid rain story” reminds me of a lesson I learned about the teacher’s lobby that involved acid rain several decades ago. My daughter was in Middle School in the early 90s and was encouraged to do a science fair project. This was in the middle of the acid rain scare, so we decided to actually measure acid rain in her school district. She collected rain water, runoff water, and lake water over several rainfalls, and measured the acidity with litmus paper. She measured a slight acidity in the rain, likely due to dissolved CO2, and none in the runoff or lakes. I thought this was significant data.

I owned a clone PC XT at the time, and had access to an HP color pen plotter and the old “Harvard Graphics” plot software. We made some great color plots of her data. My daughter had a friend who also did a science fair “project”, by looking up an article on a subject in her encyclopedia. I agreed to make a couple of plots for her, too.

The friend won a blue ribbon, and a judge told her it was because of her “great plots”. My daughter got a “participation certificate”. Obviously, finding that acid in rain water was buffered by running over the ground didn’t fit the acid rain narrative, so it was to be dismissed.

When I was in the same grade several decades before that, I did a science fair project on soil erosion. I won a blue ribbon, and a trip to the state science fair. This made a great impression on me, and helped lead to education in science and a career in engineering. My daughter was not so encouraged by her education establishment.

Reply to  Peter F Gill
February 19, 2021 7:07 am

The acid rain which was occurring until effective action reduced it?

Reply to  griff
February 19, 2021 8:23 am

Effective action ?
These “actions” started much earlier:

In 1972, the West German Constitution was amended to em-power the federal parliament to enact general air pollution controllegislation.1 Since 1974, the subject has been regulated principallyby a federal statute known as the Bundes-Immissions-schutzgesetz.2 The goals of this article are to describe the mainfeatures of the West German law, to compare it with our ownClean Air Act,3 and to offer a few criticisms of both.The stated purpose of the Bundes-Immissionsschutzgesetz is”to protect people, animals, plants, and other things from harmfulenvironmental effects” and “to take precautions against the occur-rence of harmful environmental effects.” 4 This purpose is to bepursued by a variety of measures.

Air Pollution Control in West Germany

The so called “Waldsterben” never had to do with acid rain in general, in Germany we had the air pollution prblem with our eastern nighbors and their industrial pollution.

Last edited 9 days ago by Krishna Gans
Reply to  griff
February 19, 2021 9:02 am

Which actions, specifically, and when were these instituted? Additionally you failed to couter the experiment demonstrating that ‘acid rain’ was buffered by the ground.

Reply to  griff
February 19, 2021 10:27 am

Rain is naturally slightly acidic (pH 5.5) as it is in equilibrium with atmospheric CO2.

Reply to  griff
February 19, 2021 1:27 pm

15 February 1997

By Fred Pearce
“CONCORDE, the supersonic airliner, may be destroying the ozone layer far
faster than anyone anticipated, by leaving a hitherto unnoticed fog of sulphuric
acid in its wake. Worse still, subsonic aircraft are probably doing the same
thing, adding an unexpected threat to both stratospheric ozone and climatic
Science : Aircraft wreak havoc on ozone layer | New Scientist

Read more:

Reply to  Peter F Gill
February 20, 2021 6:42 am

We were able to test it by the time CERN had build a gas chamber to simulate stratospheric conditions ( basically having been shamed for dragging thier feet for 15y when Svensmark did it in his city apartment ).

Sadly, the results were never published and director of CERN told the team any report the produced had to be “politically correct” .

dodgy geezer
February 19, 2021 2:26 am

I’m still waiting for any proof that CFCs do actually operate in the atmosphere in the way that they are claimed to do.

Jean Parisot
Reply to  dodgy geezer
February 19, 2021 9:37 am

And that effect, if any, is significant enough to justify reducing the availability of low cost, freon based refrigeration to the world’s poor and the added cost to the middle class worldwide.

Reply to  dodgy geezer
February 19, 2021 5:14 pm

“A short-lived resurgence in the emission of ozone depleting pollutants in eastern China will not significantly delay the recovery of Earth’s protective “sunscreen” layer, according to new research published Feb. 10 in Nature.”

Rephrase: “… more CFC emissions from eastern China won’t change anything; with or without CFC reduction the ozone layer will ‘recover’.”

Peta of Newark
February 19, 2021 3:45 am

Why not just tell us where the Stratospheric Ozone comes from in the first place?

Nah, thought not
That is a secret contained within The Emporer’s Wardrobe and in any case, they’re all too busy preoccupying with what’s in their ovens when they get home.
After they’ve been via the pub – to reward their self-important selves for another full day of Lying By Omission. On the taxpayer’s dime.

Bye the bye. Doesn’t the current rate of World Population Growth represent Six New Megacities being created annually? Me here is not impressed by your big numbers.

get a life please – before you trash everyone else’s.

Ed Zuiderwijk
February 19, 2021 3:51 am

I never really understood this ozone thingy. Not that that means anything. But consider this, the standard scenario. Far UV radiation, between 240 and 280 nm, is absorbed by Oxygen which splits the molecule and the free, naked Oxygen atoms combine with molecular Oxygen to Ozone. Ozone happens to absorb in the UV as well, between 290 and 300nm, a relatively narrow range compared with that of Oxygen. So, it is Oxygen that takes out the bulk of the far UV, not Ozone. Ergo, It is Oxygen that does the protecting, even if all Ozone would disappear.

David Kamakaris
Reply to  Ed Zuiderwijk
February 19, 2021 3:58 am

Interesting concept, Ed. Any idea why O2 in the troposphere isn’t turned into O3 as well as in the stratosphere? Or is it?

Ed Zuiderwijk
Reply to  David Kamakaris
February 19, 2021 5:24 am

Because the oxygen above it has absorbed al the incident far UV.

Lee Scott
Reply to  David Kamakaris
February 19, 2021 5:26 am

Far UV does not make it down to the troposphere. It’s all absorbed in the stratosphere by the ozone and oxygen. I suppose that if the ozone went away, the level where absorption occurs would simply move a little closer to the surface. The closer to the surface, the denser the atmosphere, and there is plenty of O2 to make sure it would never reach the surface.

David Kamakaris
Reply to  Lee Scott
February 19, 2021 5:51 am

Ed, Lee, thank you.

Reply to  Lee Scott
February 19, 2021 2:00 pm

Tropospheric ozone is a major component of smog, which can worsen bronchitis and emphysema, trigger asthma, and permanently damage lung tissue. Tropospheric ozone exposure is responsible for an estimated one million premature deaths each year.
Tropospheric ozone | Climate & Clean Air Coalition (

Ed Zuiderwijk
Reply to  jmorpuss
February 22, 2021 5:09 am

That ozone is caused chemically by reactions involving oxides of nitrogen produced in exhausts of internal combustion engines. It was called ‘smog’. After the compulsory introduction of katalytic converters which take out most of the nitrogen oxides the smog mostly disappeared.

John Tillman
Reply to  David Kamakaris
February 19, 2021 6:36 am

All the hard UV (UVC, with wavelength of 100-280nm) is absorbed by 03 and 02 in the stratosphere. About 90% of intermediate UV (UVB, 280-315nm) is also absorbed by the atmosphere. Soft UV (UVA, 315-400nm) gets through to the surface.

Visible light (for most people) is 380 to 700nm. Chlorophylls have two absorption peaks in blue and orange-red light, ie wavelengths around 450-475 and 650-675nm.

Last edited 9 days ago by John Tillman
Reply to  Ed Zuiderwijk
February 19, 2021 7:24 am

Stratospheric O2 blocks all the UVC (far UV) and this results in creation of O3 in the stratosphere. The O3 can absorb as well but this is negligible as the ratio of O3 to O2 is small and O3 only absorbs a part of the UVC band.

The important thing the ozone protects us from is the UVB band (the “sunburn” wavelengths), the stratospheric O3 “shades” much of the UVB band. Not all of it gets absorbed but most of it does by the time it gets down to the troposphere.

That said, from what I understand all the concern is regarding the size of the antarctic ozone hole. It has not been proven whether or not the hole was somehow caused by CFC or a natural event, as we have only been observing it for the last 60 years or so. Null hypothesis suggests the hole is a normal phenomenon, possibly filling in more from time to time due to the normal stratospheric chaos. At other places on the earth, including the arctic, I believe it has not been demonstrated that ozone levels have been significantly declining.

The few things living on land near the antarctic afaik don’t seem to be affected. The hole tends to be bigger when the antarctic is dark (winter). Because the sun is at such a low angle in the antarctic, the sin(zenith to sun) factor helps counter the effect, as the slanting rays have to travel much further through the stratosphere. So this is much ado about nothing.

Gary Ashe
February 19, 2021 3:53 am

As usual you follow the money, who got to make the billions from the substitute/s.

I cant remember the details now but i read it was a stitch up, pure bullshit as CFC’s were never proven to be doing any harm, it was something to do with the EU, and the companies involved.

Something to do with DuPonts patent expiring and a new patented product replacement, so banning CFC’s was to protect DuPont’s billions.

Last edited 9 days ago by Gary Ashe
February 19, 2021 3:58 am

Because I see commentors agree with my idjit asessment, I offer the following practical exercise:
Take half a glass of water, swirl it in a circle. Observe the low pressure vortex in the centre.
Now imagine the glass is a planet spinning at one thousand miles an hour, and the water is the atmosphere.
Unless you can PROVE to me there is no such vortex at the north pole, I shall continue deriding anyone telling me about a “hole in the ozone”.
Oh, I forget, in the south it is called a hole in the ozone, in the north it is called a polar vortex, I’m so ignorant… One day I’ll find out ozone has an electrical charge, thank goodness that’s got nothing to do with magnetic fields of the sun, because “the earth’s magnetic field loosely follows the spinning axis”, as one genius informed me recently.

February 19, 2021 4:56 am

“Despite the monitoring success story, some emissions are still unaccounted for – and scientists have been unable to pinpoint where they are coming from due to current limitations of the monitoring network.”

Is that all? Perhaps lack of cooperation by Chinese authorities contributes? By now, all should understand that the Chinese Government cannot be trusted on any subject at any time and anywhere.

Mark - Helsinki
February 19, 2021 5:04 am

Ozone destruction is part of a ground level chemical process from pollution and not related to O3 in the stratosphere at all

Nitrogen dioxide and hydrocarbons in photo-chemical reactions produce Ozone at ground level and further chemical reactions destroy that ozone as part of a longer process that leaves ends up with smog, Ozone is destroyed in the smog creating process

O3 created by UV on the other hand as we know is created by photolysis, UV hitting O2. It is not destroyed as part of a more complicated chemical reaction, due to the pollution smog not actually existing over Antarctica (unless someone can point out this, I’ve not seen such a thing)

The general public and policy makers have no idea that these are two very different worlds

If the process for destroying so much O3 in the stratosphere existed, then so would stratospheric smog, so where is it?

Mark - Helsinki
Reply to  Mark - Helsinki
February 19, 2021 5:06 am

ie, where is the pollution end point, that is to say, where are the chemical results of the ground level process, in the stratosphere? even if smog cannot form there, the chemical make up for it should exist there if the same O3 depleting process is occurring.

Thus far NOAA on twitter have never answered this for me

Andy Pattullo
February 19, 2021 8:32 am

The Montreal Protocol was an important lesson in the politics of science, but a very poor example of scientific process. Never proved the hypothesis but achieved political goals that enriched many people and made refrigeration and other industrial process more expensive with the worst impacts in the poorest nations. We are doing the same now with global warming. After achieving wealth and comfort in western nations by the use of cheap reliable energy systems we are trying to deny them to developing nations based on the myth that CO2 disrupts the many formidable natural climate processes.

Reply to  Andy Pattullo
February 20, 2021 6:39 am

Frauds of one kind or another have probably been a feature of human society since men descended from trees. But these frauds were local, the sale of a leaky kayak, the pretense of healing powers, etc. The Montreal Protocol was an example of one of the first global frauds. Globalism doesn’t just involve trade. Nonsensical ideas sweep the earth as well.

The ozone hole was such a success that interested parties quickly realized that the use of computer models, the basis of the Rowlands-Molina theory, were actually acceptable to the semi-scientific mind and that the dissemination of them became much easier with the advent of the world-wide web. So now we have the global frauds of AGW, devastating diseases that require Draconian government action, bogus elections and so on. What will be next?

February 19, 2021 8:39 am

The ozone depletion scam has been debunked for decades, yet they keep on promoting it. I guess that tells us that decades from now they’ll still be pushing the global warming scam.

S. K. Dodsland
February 19, 2021 8:55 am

I am not sure who I distrust more, NASA or China.

More GHG effect nonsense.

February 19, 2021 9:07 am

The ozone layer over the North Pole has shrunk at an above-average rate this winter. This was reported by the Jülich Research Center. According to the report, the ozone content has fallen steadily over the past three months and at the beginning of March was 18 percent below the values in winters without special weather influences.

According to the scientists led by Jülich stratosphere researchers Jens-Uwe Grooß and Rolf Müller, particularly low temperatures in the stratosphere, i.e. in the layer of air between eleven and fifty kilometers above the Earth’s surface, are responsible for this. A stable polar vortex also contributed to this, they say.  

German source

February 19, 2021 10:01 am

They don’t mention why the Chinese were making CFC-11 but they allude to it, CFC-11 is a very strong green house gas along with some of the HCFC compounds that come along as biproducts. So strong in fact that there was tremendous value in synthesizing the CFC/HCFC compounds and then destroying them to sell carbon credits to the EU. In fact 46% of the EU spending on carbon credits went to destroying the CFC/HCFC compounds. So that blip is a policy failure of epic proportions for perverse incentives.

Reply to  Ozonebust
February 19, 2021 11:39 am

Simply a natural phenomenon. Nothing to do with CFCs. But this was known before the Montreal Protocol was signed.

Clyde Spencer
February 19, 2021 11:45 am

“Stratospheric ozone, … helps shield us from the Sun’s harmful Ultraviolet (UV) rays.”

The destruction of Antarctic ozone starts in the Austral Winter, when no direct sunlight makes it to the ground, and it accelerates in the Spring from photo-catalytic decomposition of O3, when sunlight finally makes it to the ground. However, the sunlight has a long slant-range, passing through a much longer reach of air than for low-latitudes. Furthermore, the sunlight that makes it to the ground passes through stratospheric ozone outside the depleted polar region. Combined with the weak flux resulting from the Cosine Law, and the long path length, it doesn’t produce UV intensities that are of any particular concern. The chemists forget about the geometry.

Examine any map of Southern Hemisphere ozone during Winter. Two things stand out. The so-called Ozone Hole is delineated by the Circumpolar Vortex. The ‘Hole’ is asymmetrical because there is invariably an anomalously high ozone concentration outside the vortex; there is some diffusion through the wall of the vortex, replenishing some of the destroyed ozone.

As the sun climbs higher in the sky, and begins to provide a ‘threat’ that actually approaches UV levels commonly found in mid-latitudes, the air warms up and the vortex dissipates. As the ozone-enriched air mass outside the former vortex moves in to the formerly depleted region, the ozone level quickly comes back to the undepleted levels.

Note that NASA and others always cite the ozone concentration, in association with the potential for UV damage. It is exceedingly rare to see citations of actual measured surface UV fluxes. That is because levels commonly seen in the Australian deserts are never approached in Antarctica, or even the southern tip of South America.

Last edited 9 days ago by Clyde Spencer
February 19, 2021 2:06 pm

The environmental impact of emissions from space launches: A comprehensive review

“AbstractWith the increasing accessibility of commercial space flight, the environmental impacts of space launches will become increasingly significant in the coming years. Here, for the first time, a review is presented of the environmental impacts of space launches, specifically of emissions from commonly used solid and liquid rocket propellants. While there are a number of environmental impacts resulting from the launch of space vehicles, the depletion of stratospheric ozone is the most studied and most immediately concerning. Solid rocket motors are the subject of most of the environmental studies on rocket launches, while the now more commonly used liquid rocket propellants are underrepresented in the literature. The limited studies of emissions from rocket engines using liquid propellent reveal that while they do result in stratospheric ozone loss, solid rocket motors are responsible for orders of magnitude greater loss. The comparison of commonly used propellants highlights the environmental trade-offs that must be made when selecting a launch system. This review highlights the need for further study of the cumulative impacts that frequent space launches have on all areas of the environment, including global climate, ecosystem toxicity, and human toxicity, and with consideration given to all commonly used propellants, to ensure that the impacts are well characterised and well understood before the number of launches greatly increases.”
The environmental impact of emissions from space launches: A comprehensive review – ScienceDirect

Rocket launches may need regulation to prevent ozone depletion, says study (

February 19, 2021 2:33 pm

One scientists has claimed the ozone hole was cause of increased temperatures and temperature will begin to drop as it closes

February 19, 2021 7:10 pm

Do keep up. That’s all yesterday’s fish and chip wrappers and we’re into fish poop now-
Fish poop generates 1.65 BILLION tons of carbon in the ocean annually (

February 20, 2021 7:30 am

Back in the early ’90s when my son was in fourth grade, he was assigned to make a Weekly Reader type report about the ozone hole. So he got on the internet as it was at that time and did some research. After a week, he came to me saying “Daddy, this doesn’t make sense.” What he had found is that stratospheric ozone is produced by certain wavelengths of UV light, then absorbs other wavelengths of UV light so that very little of the UV light reaches the earth. However, ozone also breaks down on its own, so that when production is reduced, such as over an Antarctic winter, there will be a thinning of the ozone over Antarctica.

He also recognized that CFCs are fairly heavy molecules, making it very unlikely that any ground-based CFCs would reach the stratosphere in any significant amounts. (CFCs used to be used in fire extinguishers because of their heavy weight.)

Then I remembered something I learned in organic chemistry, namely that CFCs are some of the most stable compounds known, because of the strong affinity of the halogen elements for carbon. Especially the lighter halogens of fluorine and chlorine. That’s why chlorine is added to city water supplies as an antibiotic—it literally tears the little buggers apart to bind to the carbon.

My son was really in a bind, because researchers claimed that there was significant amounts of CFCs in the stratosphere. Where did they come from? This was shortly after the eruption of Mount Pinotubo in the Philippines. According to researchers, that eruption injected megatons each of CO2, HFl and HCl into the stratosphere (why they weren’t combined in the eruption was not explained).

My son’s conclusion based on the above was as follows: with the strong affinity of the lighter halogens for carbon, they then displaced the oxygen in the CO2 to form CFCs. The displaced oxygen ions then combined with the unstable ozone to form O2 and thin the ozone layer world wide. The displaced oxygen also combined with the rejected hydrogen to make some stratospheric H2O as well as some of the hydrogen combined to make H2. Ground based CFCs had negligible if any effect on stratospheric ozone.

The teacher was not impressed.

I learned something from my son, because I had not looked into the subject before his assignment.

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