Friday, June 18, 2010

It is probable that atmospheric scientists were wrong about CFC's

I have been troubled for many years over the world's decision to stop large scale production of a class of useful chemicals called chlorofluorocarbons (CFCs). As an operational engineer who was assigned the overall responsibility for a half a dozen or so large air conditioning and refrigeration units on board a nuclear powered submarine, I learned that those chemicals were had some very useful properties. They were used as the working fluids in compact, efficient machines that helped to maintain an environment that was healthy for human habitation, even though we were inside a steel tube, surrounded by high pressure sea water with no regular access to outside air or food resupply.

The air conditioning units kept the temperatures comfortable for both humans and sensitive electrical equipment, despite the fact that also sealed up inside that metal tube with 150 humans was a rather large steam power plant. The refrigeration units kept our food at a carefully measured temperature - some refrigerated, some frozen. Those machines were "mission critical" for us since we had to ensure that our food was fit for consumption even after being stored for months at a time.

There were other choices available for air conditioning and refrigeration working fluids, but they were all inferior for various reasons when compared to the R-12 and R-114 that we used. Some of them were wildly inappropriate for use on board a sealed submarine; ammonia, for example, was a potential option for air conditioning units in well-ventilated warehouses, but it would be deadly if it leaked inside a submarine. Vapor absorption air conditioners were an option, but there were no such thing as vapor absorption refrigerators or freezers. Those units could make chilled water as cold as 42 degrees F, but could not bring the temperature any lower due to the physical limits of the technology.

Anyone who has ever operated and maintained large, complex piping systems in the real world will know that there is always a potential for leaks; all systems on board submarines are carefully evaluated for potential health effects under worst case conditions. CFCs had been found to be non-toxic and not harmful to people as long as they did not displace so much oxygen as to cause suffocation.

That hazard was made less of a worry with CFCs because they are about 5-7 times as heavy as air and tend to pool in the very lowest spaces in any environment where they leak. On submarines, as is the case for most ships, there are deckplates installed for people to walk on that are raised above the very lowest parts of the ship - what sailors call the bilges. Those bilges are places where small amounts of water, oil and other liquids tend to fall and accumulate before they can be pumped into holding tanks for later removal from the ship.

During my assignments as an engineering officer, we experienced some significant leaks from our air conditioning units that released a substantial quantity of R-114 into the ship while underwater. Even though submarines are equipped with numerous fans for air recirculation and to ensure that no areas stagnate, we always located the Freon in the bilge, with the concentration being very high within just a few inches of the bottom and falling off rapidly as we raised the detector above that level. When we experienced the leaks, we were able to accept having Freon in our living spaces until it was convenient for us to go up and ventilate. When we did, we had to run blowers with suctions from the bilges to get the R-114 off of the ship.

The behavior of CFCs made sense to us and followed exactly what we had been taught about heavier than air vapors - they tend to sink due to gravity, though there is a certain amount of dispersion and diffusion caused by a material property called vapor pressure. The heavier the vapor, the faster it would sink. Generally speaking, heavier vapors will have less dispersion and diffusion. Since we were operators, not scientists or mathematicians, we did not need to be too concerned with the exact equations, but we did need to understand the physical behavior of these kinds of vapors.

Knowing that heavy vapors tend to sink and that lighter ones tend to rise can be a life saving bit of knowledge. If you are trying to get out of a space where there is smoke and fire, you know you should stay low, where there is better chance of finding breathable air. If you are in a space where there has been a known spill or leak of a heavy vapor that is toxic, explosive or flammable, you have a better chance of surviving if you understand that the vapor will accumulate in the lowest parts of the space and might be at a high enough concentration to burn, explode or kill you from inhalation.

It is with that experience of Freon leaks and safety training that I have never understood how the world's leading atmospheric scientists could have convinced themselves that CFCs tend to rise up through the atmosphere into the stratosphere where they are finally broken down. Even if a few stray molecules of the gas do make it up that high, it would defy gravity to believe that they did so at high enough concentrations to have caused any harm.

At the time that the scientists were convincing themselves that CFC's were destroying the ozone layer, a large portion of the CFC's that had ever been manufactured were still in the systems where they were being used as the working fluid. Though Freon and other CFC's were not terribly expensive (before their production rates were severely limited) and they were not considered to be toxic, the people who designed and manufactured refrigeration and air conditioning systems took care to build tight systems with little leakage.

Most of us take for granted the fact that we rarely, if ever, have to replace the Freon in our refrigerators or central air conditioning systems. Those leak tight systems add to the reliability and protect the rest of the mechanical components of the system; the CFCs are not only the fluid used to compress and expand, but they also serve as lubricants for the compressor and anti-corrosion fluid for the piping system.

Even if the CFCs did leak or were vented in order to perform maintenance or to dispose of the machinery after the end of its useful life, those gases tended to sink into basements, soil, crevasses, ravines, sewers, and any of countless other low spots in the cities and suburbs where most of the chemicals were being used. A small portion of the total will always disperse and diffuse because of the natural property of vapor pressure, but most of the material will sink and spread out.

For some reason, these facts about how heavier than air vapors behave did not seem to be taken into account by the scientists who study the atmosphere. In 1972, James Lovelock found minute quantities of CFCs in samples taken around the world using sensitive instruments capable of detecting levels in units of parts per trillion volume. He wrote about how these relatively inert gases could be used as tracers to show that the atmosphere mixed pretty well around the world - in the horizontal dimension.

One team of two scientists, Sherwood Rowland and Mario Molina wrote a paper that was published in the journal Nature proposing that since CFCs were stable chemicals that did not easily break down, and since they could be measured in the atmosphere around the world, they must be on an inevitable path upward into the stratosphere. According to the paper, there were no other obvious sinks for the chemicals.

As proposed by Rowland and Molina and as accepted by the atmospheric science community, the primary atmospheric sink for the chemicals was stratospheric photolytic dissociation where CFCl3 breaks down into CFCl2 + Cl and where CF2Cl2 breaks down into CF2Cl + Cl. The paper states that the Cl- ions serve as catalysts that extensively destroy O3 (ozone) and O (monatomic oxygen) in the stratosphere through the following two reactions:

Cl + O3 -> ClO + O2

ClO + O -> Cl + O2

The paper goes on to describe the atmospheric modeling used to support the theory that the catalytic reaction was having a significant and dangerous effect on the ozone layer. This 1974 paper and the validation of the proposed reactions by the National Academy of Sciences in 1976 was used as the basis for a world wide effort to ban the use of CFCs as a propellant in aerosol containers and then to severely limit its production and use in refrigeration and air conditioning systems.

According to the theory, the dissociated CFCs were the primary source of Cl- in the stratosphere, despite the fact that solid rocket motors as used for both space exploration and ballistic missiles use a substance called perchlorate (ClO4-, which releases free Cl- ions when burned. (Rockets tend to do at least some of their burning in the stratosphere while passing through.) The effort to ban CFCs moved in fits and starts, but once a 1987 NASA experiment reported that they actually measured CFC in the stratosphere (at concentrations in the pptv range with a rapid reduction as altitude increased) the effort succeeded in the widespread adoption of the Montreal Protocol.
Data from NASA's Airborne Antarctic Ozone Experiment in 1987 "provided the smoking gun measurements that nailed down the cause of the ozone hole being the increase of CFCs combined with the unique meteorology of the Antarctic," Stolarski said. Since then, NASA has sponsored several airborne field campaigns that have furthered understanding of the chemical processes controlling ozone.
What confused me then and still confuses me to this day is the fact that the multi-billion dollar effort to halt production of useful materials was based on a faulty assumption that was stated in a couple of different ways in the original article:
"There are no obvious rapid sinks for their removal and they may be useful as inert tracers of atmospheric motions."

"The most important sink for atmospheric CFCl3 and CF2Cl2 seems to be stratospheric photolytic dissociation to CFCl2 + Cl and CF2Cl + Cl respectively, at altitudes of 20-40 km."

"If the stratospheric photolytic sink is the only major sink for CFCl3 and CF2Cl2 then the 1972 production rates correspond at state to globally averaged destruction rates of about 0.8 x 107 and 1.5 x 107 molecules cm-2s-1 and formation rates of Cl atoms of about 2 x 107 and 3 x 107 atoms cm-2s-1, respectively."

I still do not get it. Heavy gases do not rise, they sink. Winds blow gases around in the horizontal dimension, but they do not often blow things straight up. The earth's surface is full of places where a heavy gas like CFCs can accumulate.

I did a quick computation once of how thick a layer of CFC's would have been if all of the world's cumulative production was simply spread out on the surface of the globe. The thickness of the resulting layer would be on the order of 4 x 10-8 meters, so it would be difficult to measure as that number would put it in the grass, in soils and under the leaf layers on forest floors. (Don't forget, a significant portion of the produced CFCs are still in the machinery where they do their work.) There would be no reason to assert - as some atmospheric scientists have done - that the vapors must dissipate upward, otherwise we would be swimming in a lake of the substance.

Another real world sink that Rowland and Molina overlooked is that CFCs break down under combustion heat - in fact, the EPA lists incineration as one of the ways that CFC's can be destroyed. There are billions of combustion devices at ground level around the world, any CFCs that are pulled in with combustion air into a furnace, an automobile engine, a fire, a boiler, or a jet engine will be destroyed by the process.

So please, help me to understand - why did the world's atmospheric scientists and government leaders agree that heavier than air vapors were rising up 20-40 km into the atmosphere at substantial quantities and destroying the ozone layer? Why did they accept that assumption and use it as the basis for taking useful and easily produced materials that help humans to better control their living conditions and store foods and medicines for longer periods of time off of the market? Why didn't the people who work with heavier than air gases on a daily basis object to this decision with a strong effort questioning the logic and the models used in by the scientists?

Why did the scientists who proposed this theory end up sharing a Nobel Prize in Chemistry for this particular theory about ozone layer destruction? Am I being hopelessly arrogant in questioning this particular episode in scientific history? After all, I have never published a peer reviewed paper in the atmospheric science literature, been employed as a scientist, earned a PhD or been awarded any prizes for my papers on other topics.

Additional Reading

Dynamics of Vapor-Air Mixtures published in American Industrial Hygiene Association Journal, Volume 26, Issue 5 September 1965 , pages 445 - 448 (Note: This link leads to the abstract. I have a copy of the full article that I can send on request to other interested researchers.)

Vapor Density and it’s influence on the Ventilation Decision Making Process

Deflagrations involving heavier-than-air vapor/air mixtures published in Fire Safety Journal 36 (2001) 693-710

Density of Gases Virtual Chembook, Elmhurst College

Sungas Information description of propane safety considerations


Huw said...

Sorry Rod, not up to your usual standards. If CFCs don't mix fully with the air column then why are they measurable at South Pole thousands of miles away from where they are released.

Why are CFCs directly measurable (from balloon and aircraft) in the stratosphere if they are too heavy to mix with the air column?

Here is a 1999 review of ozone depletion science which includes a section on atmospheric mixing and gas-exchange between the troposphere and the stratosphere. You should follow the bibliography back to some earlier papers on global circulation models. In fact putting 'global circulation model' into google scholar would probably be an enlightening experience for you.

David said...

Hi Rod,

The other factor is the way that Ozone is produced. UV light makes O3 by shining down on the stratosphere. Why they are saying that Ozone is being depleted I don't understand. You would need a decrease in UV for it to deplete. Even a chemical depletion should not affect the amount in the upper atmosphere since any lack of O3 would lead to its production. This is even more true at a parts per trillion density for cfcs

There is an association between the lack of the ozone over the poles due to the solar flux changing the strength and direction of the magnetic field of the earth.

david lewis said...

The authors of the "Dynamics of Vapor-Air Mixtures" paper, Tebbens and Ottoboni, were interested in the behaviour of heavier than air mixtures of gases in ductwork.

Their experimental apparatus was a pipe open at both ends to the air in "an interior room with no ventilation, within which no air currents were apparent".

They were aware that the behavior of gases in such an apparatus was different than the behavior of gases in the open atmosphere. This is evident from this quote from their paper:

"However, it is self-evident and known from practical experience that thorough mixing on a large scale prevents relative motion. Thus, in spite of the fact that the density of water vapor is only 41% that of carbon dioxide and 56% that of oxygen, these components of air itself do not have a tendency to fractionate under any typical conditions". - page 447

The Earth's atmosphere is the thickness of an eggshell if the Earth's size is taken to be an egg. The Earth is rotating inside this sphere of gas, and the surface of the Earth is not smooth. It seems obvious to say that the behavior of gases in a pipe or in a confined space may not be at all like how gases behave in the open atmosphere.

The rotating Earth inside its ball of surrounding gas would seem to be an efficient large scale mixer.

Sherwood Rowland, in his Nobel Lecture, addresses all of Rod's points, and more. Rowland's Nobel, that he shared with Molina and Crutzen, is the only Nobel ever awarded to anyone studying the atmosphere.

The question is not "if" CFCs and related gases get to the stratosphere, they have been repeatedly measured there and everywhere else in the atmosphere anyone ever tried to find them.

"Protecting the Ozone Layer: Science and Strategy", part of which is a history of the development of ozone science, by Edward Parson, page 33 -34, describes how Rowland published his theory in 1974, then industry and scientific groups sent representatives to a meeting where the priority issue was named - get measurements of CFCs and the related gases in the stratosphere. These measurements were obtained and published in the peer reviewed literature. Parsons footnotes three sources - Geophysical Research Letters 2: 109-12, Science, 187, no.4179 (Mar 7) 832-34, and Atmospheric Environment 11:329.

I.e., independent scientists verified what Rowland published by directly measuring the atmosphere, repeatedly. Rod writes as if the whole science is based on Rowland's "faulty assumption" which was accepted by everyone else as Pablum, which was fed into computer models which predicted unacceptable ozone depletion, which then caused world governments to issue their edict to industry to phase production of these chemicals out.

The "1987 NASA experiment" Rod mentions and tries to minimize was an aircraft flight directly into the regions of the Antarctic ozone hole where ozone concentration was the lowest, i.e. where it was almost nonexistent, which contained instruments custom designed to capture air samples to either prove or disprove the theory that this sudden incredible ozone loss was the result of CFC transport of excess Cl to the stratosphere. The theory was confirmed. There is no other explanation that stood up to examination for the ozone depletion measured over Antarctica.

Cheryl Rofer said...

You are doing a thought experiment, ignoring all the evidence (some mentioned in other comments), and saying that your thought experiment must be real and the measurements aren't. Sorry, that's not how you do science.

One thing that you learn if you've ever had a thermodynamics course is that things mix, particularly gases. The thermal motion in gases is enough to overcome whatever tendency there may be (very small) to separate by mass. So that's the presupposition many of us would start out with and could simply ignore most of the argument in this post.

You're not alone in thinking that "common sense" is enough to make a scientific argument. It's all over the "solutions" being offered for the BP oil blowout. Unfortunately, some of the intuitions that children develop and too often carry on to adulthood conflict with the real world as described by physics, chemistry, and thermodynamics. I'm thinking of writing a blog post about this general problem.

Rod Adams said...

Cheryl - yes, I am doing a thought experiment. I am pretty sure that there are several examples of thought experiments leading to some pretty interesting science, though I am way too humble to put my effort into those leagues.

I am sorry that you believe that my education and practical experience puts my questioning attitude at a level that you compare to that of a child who has stopped learning.

I am a bit surprised to learn that you believe that it is possible to successfully serve for 40 months as the Engineer Officer of a nuclear submarine without having taken thermodynamics and engaging in the routine practice of that important science.

Here are a couple more thought experiments for you.

If you release the contents of a bottle of helium into the atmosphere, what direction do you expect those contents to travel?

If gases do not tend to separate based on density, how do centrifuges succeed in achieving some separation of gases even when there is a tiny percentage difference in their masses?

David Lewis quoted from a Tebbens and Ottoboni paper titled "Dynamics of Vapor-Air Mixtures" that was published by the School of Public Health, University of California in Sept-Oct 1965. Here is a quote from the paper's conclusion.

"Gumaer observed the evaporation of benzol from a table top and described a waterfall type of downward vapor flow from the edge of the table. Vapor concentration patterns directly above the evaporating liquid and at the edges of the table suggested that the influence of gravity was very important in comparison to diffusion of dispersion by random air motion as a mechanism for dissipating the vapor. This fact was brough out by Zabetakis et al in experiments in which the floor level was the evaporation point for rather large quantities of liquid ether. Under these conditions, the persistence of rich mixtures very near the floor level and the absence of significant upward dispersion or diffusion also illustrated the need for considering the effect of vapor density in describing the system dynamics."

"In reviewing possible ways of studying the mechanics of free-falling vapors, several ideas show promise. The application of dimensional analysis could be the route to relating flow variables for a variety of systems. Visualization of flow patters, a necessary part of such a study, is possible with shadowgraph of Schlieren methods. The results of such work would be a contribution to the fields of industrial hygiene and air pollution control."
p. 448

As an aside, my education as a professional naval officer and as an ocean sailor included several courses in meteorology and a fair amount of field experience in weather pattern observations, measurements and predictions. I am no expert in the field, but the following quote from David Lewis's comment is not a terribly accurate model of the earth's relationship with its atmosphere.

"The Earth's atmosphere is the thickness of an eggshell if the Earth's size is taken to be an egg. The Earth is rotating inside this sphere of gas, and the surface of the Earth is not smooth. It seems obvious to say that the behavior of gases in a pipe or in a confined space may not be at all like how gases behave in the open atmosphere.

The rotating Earth inside its ball of surrounding gas would seem to be an efficient large scale mixer. "

GRLCowan said...

I share Huw's surprise that Rod is still having trouble with this. Yes, you can pour CO2 out of a beaker, onto a tabletop, and have a CO2-fall off the edge of the table.

If you spill too much CO2 in this way -- more than about five percent of the room's volume -- and the room is sealed, and you can't get out, the CO2 will get you, even though you take care to inhale only at points higher than 5 percent of the way from floor to ceiling. Why is that, Rod?

Or is it untrue, and could people who have died in confined spaces have saved themselves just by keeping their heads high and holding very still?


where CFCl3 breaks down into CFCl2 + Cl and where CF2Cl2 breaks down into CF2Cl + Cl. The paper states that the Cl- ions serve as catalysts that extensively destroy O3 (ozone) and O (monatomic oxygen) in the stratosphere through the following two reactions:

Cl + O3 -> ClO + O2
ClO + O -> Cl + O2

you confuse Cl and Cl-. Totally different. I doubt perchlorate oxidizer in rockets produces much Cl, because in the absence of fuel, perchlorate's spontaneous tendency is to decompose like this,

MClO4 ---> MCl + 2 O2,

and if MCl splits up, M being H or Na or K, it does so into a positive ion and a chloride ion, not a chlorine atom.

(How fire can be domesticated)

Brian Mays said...


First, let me say that it's good to maintain a skeptical attitude and to keep asking questions. There are no silly questions, only silly answers.

As far as CFC's are concerned, I don't think that it is too implausible that somewhat heavy gasses are able to loft high into the atmosphere and be spread quite far about the globe. The rather static conditions on your boat were quite different from the dynamic conditions encountered in the atmosphere. Did the bilges on your sub have any active ventilation when you were not on the surface trying to evacuate with blowers?

Meanwhile, the atmosphere is driven by winds that are typically on the order of ten meters per second. That alone leads to significant mixing. Then you have to consider what happens when one mass of air bumps up against another. For example, consider what happens at a cold front (a rather common occurrence). When a mass of warm air encounters a mass of cold air, the warm air is forced up and over -- almost as if the cold air were a plow pushing the warm air over it. Any chemicals entrained in the warm air are lofted up to great heights in this process. Once high in the air, the heavy ones still take a long time to settle back down.

Think about an inhomogeneous solution (e.g., typical Italian salad dressing). Once it is shaken up, it takes a while to settle back down into layers. This is a liquid in a bottle that is allowed to sit stagnant (and sometimes with surface tension helping the process). For gasses blown on the wind at much larger scales, the process should take much longer.

Getting back to the Montreal Protocol, was the case overstated? Well, given the socio-political environment at the time, I'd say that it's possible, maybe even probable. I'm not an expert in atmospheric chemistry, so I won't venture a more certain opinion than that. Nevertheless, there were certain other hypotheses that were being put forward by the same crowd at roughly the same time (e.g., nuclear winter) that turned out to be very overstated, almost embarrassingly so. Thus, I wouldn't be surprised if some of these other claims were similarly flawed.

The real question is will we ever know. Perhaps we will sometime, but that won't be for a while. The CFC production ban (it is still allowed to be used) has not been extremely expensive, so there are not many people who are willing to pay close attention to this issue. We still don't understand at a convincing, fundamental level why the ozone hole exists in the Southern Hemisphere, and as long as there are air conditioners that continue to use CFC's -- whether they leak or not -- there will always be a way to explain the hole's existence with the conventional CFC theory.

Finally, a few corrections to some of the comments here:

"Thermal motion in gasses" -- i.e., diffusion -- does not sufficiently explain the mixing of gasses in the atmosphere on a global scale. The main driving forces are advection and turbulence.

"Global circulation models" should be general circulation models.

Rod Adams said...

@GRL - Thank you for the clarification of the difference between Cl and Cl-. I got that one wrong.

When I mentioned perchlorate, however, I was not talking about the material in the absence of fuel. I was thinking more about the combustion products that are released when a rocket burns with perchlorate as the oxidizer.

In that case, isn't Cl (not Cl-) a reaction product?

Rod Adams said...

@Brian - Good comments about atmospheric mixing and the turbulence found once you get above the surface of the earth.

I am not denying at all that CFC's have "been measured" in atmospheric samples all over the world, or even that they "have been measured" in the stratosphere. My question is more about "how much" has been measured and if those measurements indicate that a majority of the material that was ever produced has found its way up into the stratosphere to be decomposed.

If mechanisms like gravity and density are working for CFCs like they do for other heavier than air gases, I postulate that a large majority of the material remained right at ground level - where there is a lot of stagnation in basements, sewers, valleys, ravines, soil furrows, rocky outcroppings, forests, suburban foundations, wells, etc. - and only a small fraction got diffused due to vapor pressure.

Some commenters have mentioned CO2 which is slightly heavier than air - (molecular weight of 44 versus an average of about 29 for air). Is that really a good analog for CFCl3 which has a molecular weight of 137 or CF2Cl2 which has a molecular weight of 120?

For liquid mixtures, the rate of separation after stopping the mixing process has some relationship to the difference in specific gravity - it takes more time and the separation is less complete when the specific gravities are relatively close. Based on the paper about gas dynamics, it would seem reasonable to suspect that the same effect is true for gases where those close in density will remain relatively well mixed for a longer period of time while those mixtures with a large difference will separate more completely and more rapidly.

By the way - I fully intend to progress at some point from a thought experiment to a real experiment with measurements. I am not a scientist and not experienced at setting up valid conditions, so I am open to suggestions.

At this point, I am thinking about an environment with a relatively large vertical dimension and a complex surface at the bottom. I am visualizing a floor that resembles the model train setups that I have seen or the models that architects use to sell developments that have lots of green space between concentrations of housing and commercial buildings. The chosen model will have to have some areas that represent basements, sewers and subways.

Of course, there will be several high capacity fans with on and off switches to simulate the movement of air at ground level. (We all live at ground level - if you really believe that the air is always moving, you did not grow up in the south or spend much time walking around DC in July, February and August.)

Rod Adams said...

I found an experimental paper that provides some interesting data. I am not sure yet whether it conclusively proves my theory incorrect, but it does provide measurements supporting the assertion that gases - especially light gases - mix reasonably well just by diffusion.

The measurements do show that heavier gases take much longer to move and change concentration.

DIFFUSION OF GASES IN AIR AND ITS AFFECT ON OXYGEN DEFICIENCY HAZARD ABATEMENT J. C. Theilacker and M. J. White, Fermi National Accelerator Laboratory Batavia, IL, 60510, USA. FERMILAB-CONF-05-635-AD

Brian Mays said...


One challenge of setting up such an experiment is that you have to get the relative scales correct. Air in the open atmosphere behaves quite differently than air in a room, because the scales are different. For example, the molecularly viscosity of air is so small compared to the large scales of planetary air flow that the atmosphere can essentially be taken to be an inviscid fluid.

The first step in planning any sort of experiment is to ensure that the proper dimensionless quantities have the right values.

Cheryl Rofer said...

Hi Rod -

When a thought experiment conflicts with observation, as yours does, it's time to rethink. What you expect helium or CFCs to do in the atmosphere is irrelevant; what they are observed to do is what's important.

I'm sorry if it seemed like I was saying that your thinking was childish. I was referring to recent experiments and observations (those mainstays of science again!) that show that children start out with some expectations that aren't borne out by science. If you haven't learned the science, you're likely to stick with those expectations. That's all I was saying.

And if you've taken a thermodynamics course, you'll know that the driving forces involved in your thought experiment overwhelmingly drive toward mixing. If you've taken elementary chemistry or p-chem, you'll know that molecular dynamics drive toward mixing. And if you've taken any science courses at all, you'll know that when observation conflicts with your expectations, you need to rethink.

Rod Adams said...

Cheryl - just out of curiosity, do you know what the boiling point of R-114 (one of the common forms of Freon) is?

What happens to a gas when the temperature drops below its boiling point for an extended period of time?

Did Rowland and Molina start their campaign after having observed CFC in the stratosphere or did they start it after having predicted that they would find CFCs in the stratosphere if they looked there?

dave (katana0182) said...

This page provides an answer as to the question of atmospheric diffusion of CFCs - and why CFCs and other generally non-reactive gasses are pretty uniformly distributed throughout the atmosphere regardless of altitude.

As for the question as to why the main sink of CFCs is photolytic decomposition, rather than combustion, bilges, caves, and crevasses, the volume of the sink is probably the answer. The reactive volume of the stratosphere where photolytic decomposition can take place is orders of magnitude larger than the sum of all areas where CFCs could be destroyed or captured.

Perhaps this planet has 1000 km³ of volume continuously undergoing combustion processes. Say there are 25000 km³ of caves and crevasses where air movement is not disturbed. Compare these volumes to the volume of the stratosphere, which is the atmosphere from 15 to 50 km.

Neglecting that the Earth is not a perfect sphere, let us take the radius of the Earth at sea level, which is 6378100 m, add 15000 m to exclude the troposphere, giving us a radius of of 6393100 m. v(sphere) = 4/3πr³, so v(earth and troposphere)=1.09451e21 m³. Do the same calculation using a radius of 6428100 (as the stratosphere is 35000 m thick) and you get v(earth, troposphere, stratosphere) = 1.11259e21 m³. This gives a volume of the stratosphere of 1.808e19 m³, or 1.808e10 km³ (1 km³ = 1e9 m³). This is a LOT of reactive area. Think about it for a second. 18.08 billion cubic kilometers of stratosphere. Compare to our high estimates of 1000 cubic kilometers of space undergoing combustion processes, and 25000 cubic kilometers of undisturbed air spaces that high-weight gasses can be trapped in.

Cheryl Rofer said...

In response to your latest question, look at the phase diagram. Boiling point depends on pressure, another elementary fact from p-chem and thermo.

I see another problem in your intuition: yes indeed, gas centrifuges separate gases according to mass, but only because of their large input of energy, as required by the laws of thermodynamics. The gases don't just hop apart.

And I'll quote from your quote: The rotating Earth inside its ball of surrounding gas would seem to be an efficient large scale mixer. Not to mention the thermal activity from the sun and the warming earth.

GRLCowan said...

What happens to a gas when the temperature drops below its boiling point for an extended period of time?

Depends on its partial pressure.

I am thinking about an environment with a relatively large vertical dimension and a complex surface at the bottom.

If you can get glass tubing that your CFC detector can get its nose into, you should start with a simple bottom surface.

With the tube sealed at the bottom, see if any CFC can be detected at the top, open end. Drop in an ampoule of CFC so that it breaks at the bottom, seal the top, and let it sit in the dark for a few months. This is a pure diffusion experiment, no turbulence.

Then flame-pinch it shut about two-thirds of the way up, remove the upper section that now is separate from the lower section, have the first Alpha Centauri expedition take it with them and break it open when they are there. (So as to be sure very little CFC can sneak from the sealed lower part to the sealed upper part.)

Compare their CFC detection in the top part with your initial one.

If this shows that the CFCs diffused upwards purely through the spreading of thermal energy into the nonthermal form of heavy molecules' mgh, it becomes unnecessary to determine whether they would get carried up by turbulence.

You could also try it with similarly heavy, non-CFC molecules that an actual nose can easily detect; geraniol comes to mind.

(How fire can be domesticated)

GRLCowan said...

When I mentioned perchlorate ... I was thinking more about the combustion products that are released when a rocket burns with perchlorate as the oxidizer.

In that case, isn't Cl (not Cl-) a reaction product?

Chlorides are very stable. The exceptions are oxygen and nitrogen chlorides, or as the former are sometimes called, chlorine oxides.

So photolysis of very dilute CFC molecules in the upper air can free a chlorine atom without giving it any prey.

But HCl is a very stable material. I looked a few years ago at what the minimum-energy state of Shuttle SRB propellant would be, and it looked to me like this:

   Al + 0.4 C4H6 + NH4ClO4 --->
     (1/2) Al2O3 + (1/2) N2 + HCl +
     1.6 CO + 1.8 H2 + 0.9 H2O(g)

The only way for some of the chlorine to end up free would be to miss all the free hydrogen, deep holes for it to fall into.

(How fire can be domesticated)

Rod Adams said...


The boiling point of R-114 at 14.7 psia (standard atmospheric pressure at sea level) is 38.4 degrees F.

For at least part of the year in many parts of the globe, that particular material will be a liquid, not a gas, on the surface of the earth and for quite a few feet above the surface of the earth.

@GRL - since I have no expectation of any Alpha Centauri expeditions in my lifetime, I guess I will have to think of another way to experiment.

Does the length of the tube have any impact on the validity of the pure diffusion experiment? Would one expect a different result at the far end of the tube if it was 20 meters tall vice 1 meter tall? How about if it was 200 meters tall? (Maybe I can get permission to use the inside of a wind turbine tower.)


GRLCowan said...

The boiling point of R-114 at 14.7 psia (standard atmospheric pressure at sea level) is 38.4 degrees F.

For at least part of the year in many parts of the globe, that particular material will be a liquid, not a gas, on the surface of the earth and for quite a few feet above the surface of the earth.

You know that snow and ice can evaporate when it's far below freezing, right?

If one mole of R-114 is dilute in 999 moles of air, one would expect it to remain gaseous down to the temperature where its vapour pressure is 0.001 atm, not 1 atm.

(How fire can be domesticated)

GRLCowan said...

Does the length of the tube have any impact on the validity of the pure diffusion experiment?

Some. Very little, I think.

Would one expect a different result at the far end of the tube if it was 20 meters tall vice 1 meter tall?

Predicting how different comes under the heading, I think, of "baroclinic ideal gas theory", which I'm not on top of.

But I would expect you can get pretty close by assuming the CFC molecules and the air molecules will, in their minimum-energy state, both distribute themselves vertically just as they would if they were the only ones there.

That means the density of the air will vary exponentially with an e-fold reduction distance, aka the "scale height", of 101325 Pa/(1.2 kg/m^3 * 9.80665 N/kg), where 9.80665 N/kg is the terrestrial gravitational constant often known as 'g'. This scale height, as I recall, comes out near 8.5 km.

Air's molar mass is 29 g. CFCl3's is near 137.5, so we expect an atmosphere of pure CFCl3, that we assume to behave as an ideal gas, to have a scale height of 8.5 km times 29/137.5, of 1.8 km.

Recall that we're assuming the mixture will behave like two pure atmospheres that ignore each other. That means the air will continue to have its customary 8.5-km scale height and the CFCl3 will have a scale height of 1.8 km.

So if we start with thoroughly mixed air-plus-CFCl3 in a 200-m wind turbine tower's internal space, and leave it to itself for a time which I guess would be on the order of years, the CFCl3 will settle until its concentration at the bottom is exp(200/1800) times its concentration at the top; 1.12 times more concentrated.

If we start with all the CFCl3 at the bottom, we expect it to diffuse upwards until the same minimum-energy state is reached: concentration nearly uniform, nine at the top if it's ten at the bottom.

But if there are stairs inside the tower, and you start with the uniform mixture and every week take a measurement at the bottom and then walk up and measure again at the top, I don't think you'll ever see any settling.

(How fire can be domesticated)

david lewis said...

Mays: "We still don't understand at a convincing, fundamental level why the ozone hole exists in the Southern Hemisphere"

I wonder what "convincing, fundamental" level that might be. What is usually taken as "convincing" evidence that a theory is sound is when predictions that would otherwise not be looked for are made by the theory, which are confirmed by observation. There are also no other theories that can explain why ozone disappears in the way it does over Antarctica.

Mays has attacked me personally in the past, by comparing me to a "Moonie" cranking out religious gibberish. He did this because I had pointed out to him what the views of the President of the National Academy of Sciences on the "climategate" incident are, i.e. President Cicerone has stated in an editorial in Science that this controversy has not diminished the understanding that climate scientists have at all.

Mays repeatedly expressed his scorn, told me he had an actual PhD and that I knew nothing, and then compared me to a religious fanatic as well as a drinker of KoolAid. I was astonished at first.

I didn't expect to find such vehement rejection of an entire scientific discipline in anyone participating in a nuclear power forum, because I have heard and read so many discussions among pro nuclear types as they criticize and laugh at their foes, the anti nuclear types, who irritate and amuse pro nuclear types as they reject what science has discovered about radiation and nuclear power.

I brought up the subject of ozone depletion on Rod's The Atomic Show blog, thinking it might bring out whether there were any ozone science deniers frequenting it. I was interested in finding out more about how far this denial of science goes.

Not long after that, Rod chose to discuss his ideas of ozone depletion with me in private emails. After that exchange, Rod posted this topic in this forum.

As comments must be of limited length in order to be accepted by the blog software, I will continue in a separate comment.

Marje said...

You are right to question CFCs. This was an elaborate scare scenario designed to prepare the way for the larger snow job of "global warming." It's actually the "believers" who are denying the science of the matter. We published documentation on this in 1992, the book "The Holes in the Ozone Scare: The Scientific Evidence That the Sky Isn't Falling," which includes a chapter reprinted from the 1968 book by Gordon Dobson, "Exploring the Atmosphere." Dobson discovered the "ozone hole" in the 1950s, before CFCs were widely used. In fact, the units that measure ozone in the atmosphere are named dobsons, after him. As Dobson reported from his observations in the 1950s, Antarctic ozone fades away from August to November. It is a natural phenomenon.
Why the hoax? At the time, we stated that the purpose was depopulation and deindustrialization. The leading propagandists for the hoax attended that 1975 meeting organized by Margaret Mead to promote the idea that to preserve the "atmosphere," human beings in the industrialized nations must curb their living standards and people in the Third World must simply die.
The ozone book is available at our website store:
For the Mead story, see see

david lewis said...

Rowland's original theory, that CFCs would cause ozone depletion, was tested and refined by himself and many other groups for more than a decade up to 1985.

(For simplicity I will just say CFCs from now on, although many synthetic gases containing Cl and Br are important)

Still, skeptics of the time pointed to the atmosphere itself saying where is the depletion. The problem for the theory as it had evolved to that point was that it indicated that the concentration of CFCs present in the atmosphere as of that date would cause a level of ozone depletion so small that it could not yet be convincingly measured, as the "signal" had yet to emerge convincingly from the "noise". Even though many ozone readings existed that seemed very low to types like Rowland, because ozone is naturally variable, general agreement that any global or regional ozone depletion had been measured did not yet exist.

In 1985, as now, no dispute existed among scientists doing current state of the art research publishing in peer reviewed journals, including those hired or funded by the CFC industry, about the question of whether CFCs reach the stratosphere, because direct measurements starting in 1975 had always confirmed it in amounts and places consistent with scientific understanding of how gases behave in the open atmosphere.

What the debate had evolved into by 1985 was, what ultimate ozone depletion could be expected at the "steady state", and was this a matter of concern. A "steady state" of CFCs in the atmosphere would occur after many more decades of increasing emission, as it was expected that at some point the sources would tend to equal the sinks for these gases and the atmosphere would contain, roughly, as much as it would ever contain. In 1985, the concentration of CFCs was rapidly increasing.

When Farman published what he had discovered by measuring ozone levels over Antarctica over a number of years, in 1985, atmospheric chemists felt it would prove to be the first undisputed observation of ozone depletion. There were some atmospheric scientists who disputed this. These scientists said that ozone poor air must be moving into the area. This idea had some credibility, because there is a big change in air movement in the region in springtime, roughly coincident with the appearance of the ozone hole. There are winds that blow all around Antarctica unrestrained by land masses which some call the polar vortex. These winds maintain relatively undisturbed air over Antarctica for the entire winter, but this isolation breaks up as the wind pattern changes in the Antarctic spring, driven by the appearance of the Sun.

The atmospheric chemists were originally stunned by the speed and magnitude of the reaction that must be taking place if the ozone hole was caused by chemical reactions, as their understanding up to that point ruled out the possibility that changes at this rate could happen. However, no atmospheric chemist had, until then, considered that there might be ice particles in the stratosphere. The Antarctic stratosphere does contains ice particles, and these were noticed by early explorers of the area as the high Antarctic clouds seen nowhere else on Earth. This information had not been taken into account by atmospheric chemists. The ozone hole caused atmospheric chemists to turn their attention to the region.

david lewis said...

Paul Crutzen studied the new evidence of apparent massive ozone depletion coming from studies of Antarctic data and concluded that the ice particles everyone now realized were present in the Antarctic stratosphere radically changed the theoretical understanding of what CFCs could do. Crutzen explains in detail in his Nobel Lecture. Basically, in places where no ice exists in the stratosphere, nitrogen compounds restrain the chlorine catalytic destruction of ozone, but when ice appears, these nitrogen compounds disappear, setting the chlorine free to finally show us what it can do, causing massive ozone loss. The new theory was refined by researchers experimenting in laboratories and using computer simulations of stratospheric conditions.

However, the gold standard remained the measurement of the atmosphere.

Instruments were constructed that were taken into the ozone hole by an aircraft which captured and tested samples of the atmosphere there. Crutzen: "The general validity of the chain of events leading to chlorine activation has been confirmed by both ground based (75,76) and airborne in-situ (77) radical observations. Especially the latter, performed by James Anderson and his students of Harvard University, have been very illuminating, showing large enhancements in ClO concentrations in the cold, polar region of the lower stratosphere, coincident with a rapid decline in ozone concentrations. Together with other observations this confirms the correctness of the ozone depletion theory as outlined above."

david lewis said...

It seems Rod's final word came right at the start: in his title. "It is probable that atmospheric scientists were wrong about CFCs".

Like an "anti" nuclear protestor at a public meeting arguing that radiation is much more dangerous than radiation scientists have discovered, Rod accepts no evidence as valid except that which reinforces his beliefs.

What is "probable", what is extremely likely, is that Rod is wrong.

If Rod is right, the scientists who studied ozone depletion don't know how to measure gases, and they don't know the first thing about how gases behave in the atmosphere. They do not know if relatively heavy gases mix into the atmosphere in the ways they say they do, because they just make up their theories about how gases behave without confirming by observing reality. If they had confirmed what they say by obtaining reliable measurements, there would be no room for Rod and his theory that they are wrong.

The scientists are stupid, or they just make things up, or they lie about what they actually know in order to pick on industries such as the chemical industry that produced the CFCs, or perhaps they were all bought off by Du Pont, who Rod says had patents expiring and needed chemicals outlawed so they could patent the substitutes.

Everyone in the world is corrupt or lying, except for the chosen by Rod few who don't, i.e. people in the nuclear industry and some others.

Rod, who doesn't make the study of gases in the atmosphere his main concern, knows more than all the people who do make the study of gases in the atmosphere their main concern. Rod says his assessment of the quality of the work of scientists studying ozone is better than the National Academy of Sciences can come up with, even after repeated assessments done by the NAS over the decades.

At some point, in my debate with Rod that started in private correspondence, I concluded he doesn't understand much about how science works, or what it is.

He wants to pick and choose from scientific literature what he likes, and deny as corrupt lies those papers he doesn't like.

He points to the National Academy assessments of science when he likes what they say, and he tells other people to pay attention, as he did in his most recent Atomic Show podcast, #155. He put on a discussion between Lisa Stiles and Greg Jaczko about a NAS study of cancer near nuclear plants.

Why should anyone take what the NAS says seriously on any topic, if what Rod says about ozone is right?

Gene said...

Rod, I too, have had some of the same thoughts. The general public thinks I am a nut case. Just prior to reporting to USS BAINBRIDGE (CGN 25), 4 sailors died because of their response to a Freon leak. During a cross country trip between duty stations in 1996, I was rerouted near Regis, Montana, due to a derailed train that dumped Chlorine gas. The cloud never got above the tree tops.
Interestingly, during briefings prior to my tour on CVN 68, I was instructed to never buy Freon, because the DoD stockpile was sufficient for quite a number of years.

Here's the conspiracy theory. The patent on the CFCs was soon to expire. To keep the corporation viable, R-134A needed to be patented and become the refrigerant of choice. (It is much less effective than R-12 or R-114.) Seems too convenient that suddenly the CFCs are found to be destroying the ozone layer. Being forever the skeptic, I attempted to find out for myself. The lack of published literature on CFCs and ozone depletion was astonishing, given the level of hysteria in the press. This was in 1996. Later, when I finally did corner some literature (the scientific stuff, not magazine articles), I was amazed to learn that there is a production mechanism for ozone. Isn't that interesting? Seems when the public was being alarmed and we were all going to freeze to death or fry (can't remember which, just now), that fact was left out of the picture painted for the American people.

The climate change folks are just as duped as the ozone depletion folks, but that's another subject. I've read much more on AGW, and the scientific process was not followed. Had I constructed and defended my thesis (Masters and Post-Masters) in the same manner as the bulk of the global warming (climate change, now since cooling as been observed for nearly a decade) literature, I'd not have the degrees. I would have been laughed out of the school. I've yet to figure out how and why their trash is believed and accepted.

Same story for ozone depletion. The published "science" doesn't support the claim(s). Any number of conspiracy theories are unfortunately a lot easier to believe.

Keep on questioning. I'll keep up with the attitude!

Rod Adams said...

@Gene - you bring up an interesting point that I have not yet written about.

The concentration of O3 in the upper atmosphere is a equilibrium number that is the result of a differential production and loss mechanism. O3 is not a stable molecule; it normally gets destroyed by a variety of decomposition methods.

There is a production method in the upper atmosphere that requires the same UV light that is said to be the destruction mechanism for CFCs.

The concentration of O3 reaches a quasi steady state value when the rate of production from UV interactions equals the rate of natural loss due to decomposition. (Nukes are pretty well versed in this kind of steady state equilibrium based on differential equations through experience with xenon concentrations and criticality computations using the six factor formula.)

There is an interesting phenomenon that happens every year right before the Antarctic spring. It is called "winter" and the sun disappears for several months in a row. If you look at the factors in the differential (which are more complicated that I am summarizing here in a blog comment, but I am aware of them and have studied them) the production factor is essentially zero for several months while the decomposition factor remains. That means that the concentration of O3 steadily falls throughout the winter.

Surprise, surprise - when the sun again becomes visible the intensity of UV radiation hitting the land is quite a bit higher than it was right before the sun disappeared. There is a lower concentration of O3 that remains until the production rate catches up to the loss rate. As the sun's energy input to the Antarctic stratosphere increases with the season, the production rate actually overcomes the loss term and the concentration of O3 begins to increase until it falls off as the sun gets lower and lower in the sky and provides less and less energy with the approach of winter.

Part of the reason that the stratosphere above the South Pole is not replenished with O3 from other regions of the world where the sun is still shining brightly and producing O3 is that there is a circular pattern of wind over the pole during the winter that semi-isolates the air column directly over the polar regions.

Of course, I am going to be accused of being a science denier and be accused of failing to read all of the peer reviewed works that explain why these mechanisms have all been investigated and proven to not be worth much mention in the scare story told to the rest of the world to make them decide to stop producing useful chemicals that cost far less than their overall value to society.

GRLCowan said...

Of course, I am going to be accused of being a science denier ...

Not by me. If you think the expected charge will be untrue or unkind when it comes, try to set your expectation of it aside and discuss the points I have made.

Rod Adams said...

@GRL - I was not directing my comments at your helpful suggestions for experimentation. I have not yet answered them mainly because I am considering how to put them to the test. The results of the experimentation might help to convince me that I am either totally misguided or perhaps on to something worth pursuing.

Last time I took a science class, the goal seemed to be about observing reality, producing a hypothesis and then testing to try to disprove the hypothesis. Again, as I have pointed out on any number of occasions, I am NOT a scientist but a guy who likes to use technical knowledge to make life better for people. I like to apply well understood principles, not come up with new theories about how many angels I can get dancing on the head of a pin - if I can manage to figure out a way to detect the angels in the first place.

GRL wrote:

"If we start with all the CFCl3 at the bottom, we expect it to diffuse upwards until the same minimum-energy state is reached: concentration nearly uniform, nine at the top if it's ten at the bottom.

But if there are stairs inside the tower, and you start with the uniform mixture and every week take a measurement at the bottom and then walk up and measure again at the top, I don't think you'll ever see any settling."

Isn't the issue with CFCs that they do not start out in a uniform mixture? The applications that concern me are refrigerators, freezers and air conditioners. In those applications, the CFCs would come out in rather concentrated form - if they come out at all. The machinery will often be located in areas where the air flow is not terribly good, though admittedly some of the potential leaks will occur in air handlers where the very design of the system gives the CFC's an initial boost in the upward direction and helps to start the mixing process.

If there is a leak from a concentrated source of CFC at the bottom of a sufficiently tall environment with some amount of surface complexity and discontinuities - will most of the material remain low, will it equally diffuse throughout the column so that the concentration at the very top is the same as the concentration at the very bottom - but the majority if the material is located somewhere in between - or will the material preferentially rise out the top of the column?

In my understanding, it is the third proposition that the effort to ban CFC's was aimed at halting. Under the currently accepted, Nobel Prize winning theory, CFCs would be released at ground level, would mix with the atmosphere in a uniform manner around the globe. Those stable gases would remain suspended in the atmosphere until such time as they made their way up into the stratosphere where they would be destroyed by UV, release free chlorides and destroy as much as 100,000 times as many molecules of O3 via a catalytic reaction.

Please correct my summary if that is not what Rowland and Molina said in their papers, conferences and frequent press conferences warning all of the rest of us that we had to stop the production as quickly as possible. Please tell me if that is not the scenario that was accepted by the atmospheric science community and served as the basis for passing the Montreal Protocol.

It is quite possible that I am completely off base by suggesting that this scenario does not quite pass the logic test that I was trained to put to use in my role of responsibility for the lives of other people while serving with the collateral duty of atmosphere control officer in a sealed environment full of people.

It seems that a few simple experiments might help me to figure out one way or another if I am being nutty.

Can anyone point me to a good supplier of Freon measuring equipment?

Rod Adams said...

@David Lewis

You wrote:

"He points to the National Academy assessments of science when he likes what they say, and he tells other people to pay attention, as he did in his most recent Atomic Show podcast, #155. He put on a discussion between Lisa Stiles and Greg Jaczko about a NAS study of cancer near nuclear plants."

I am pretty sure that is a misinterpretation of my writing and publication efforts. I rarely, if ever, point to a bureaucratically appointed body and advise people to accept their published summary conclusions without question.

On the most recent episode of The Atomic Show that you mention, I published an interview by Lisa Stiles of the appointed chairman of the NRC. Please help me understand what I did in that effort to share my own thoughts on the proposed study?

It does not matter to me how many distinguished and credentialed scientists tell me that tiny amounts of radiation are hazardous when I can see for myself the results of actual interactions. It does not matter to me how many distinguished scientists tell me that wind and solar energy systems can provide reliable energy when I can stand outside for a day and realize that the sources of energy being collected by those systems are not steady or reliable.

I try to apply the same logic and questioning attitude in all topics.

GRLCowan said...

... Those stable gases would remain suspended in the atmosphere until such time as they made their way up into the stratosphere where they would be destroyed by UV, release free chlorides ...

Again, chlorine (monatomic), not chloride.

(How fire can be domesticated)

david lewis said...

Rod - you say "please help me understand what I did in that effort [publishing the interview Lisa Styles did with NRC chairman Greg Jaczko] to share my own thoughts on the proposed study?"

You expressed your thoughts at the end: "I hope that it shows exactly what most of us believe, that nuclear facilities have no adverse effects on their local community, particularly at the levels of radiation that the facilities have been measured and known to release". I agree that in this concluding statement you do not take a position on whether the NAS is capable of assessing anything or that anyone should pay any attention to what they say on any subject.

Instead of writing about you saying "he points to the National Academy when he likes what it has to say" I should have said, in this case, that it is strange that you appear to take the National Academy seriously, given that you appear to believe they don't know how to assess the scientific literature on ozone depletion. If you are correct that no scientist publishing in the literature knew how to measure CFCs in the atmosphere and that all theories of what effects these various gases have on ozone in the stratosphere have no relation to reality because they could not have been verified as the CFCs were not present in sufficient quantity to do anything, it is clear, if you are right, that the NAS did not notice that all of the scientific literature on ozone is consequently either faked or in error.

Repeated assessments by the NAS since 1974 have come to the same conclusions about basic facts which you've stated are "probably" wrong. These assessments contributed much to the destruction a sector of the chemical industry and caused users of the chemicals in question to implement large investment programs to retool to use substitutes.

Anyone might think that an organization like this, i.e. the NAS, after this, what would you call it, ozone debacle, or gong show, should be disbanded. Any time they came close to even looking at an aspect of an industry you care about, i.e. the nuclear industry, one might think you'd be a bit nervous, wondering what this collection of Bozo the Clowns was liable to come up with next. And what of the institutions that support all the scientists who faked or published complete gibberish, i.e. the great universities and research institutions of the world? How could it be that not one of them was able find and employ one single scientist who would actually do some worthwhile research instead of making things up or bumbling around making stupid errors, i.e. figure out how to measure CFCs, then measure them, in order to realize that they are too heavy to get to the stratosphere in great enough quanitity to do any damage?

How can you then make fun of or brand as freaking nuts the anti nuclear protestors who question whether what scientists who study radiation have found has anything to do with reality?

Rod Adams said...

@David - I apologize for causing confusion about my feelings regarding whether or not I agree with Jaczko's decision to ask the NAS to expend government money to study something that has already been adequately studied.

Let me try again - I think it is a stupid waste of money to pay for additional studies to find out whether or not nuclear facilities - especially the commercial facilities for which the NRC has jurisdiction - are causing any health issues for people in their surrounding communities. The evidence is so clear already - the quantity of radiation and radioactive material being released is well known and heavily monitored. The health effects of that quantity of dose are also well understood to be so close to zero as to not matter whether they are a bit above or a bit below it. Any effect disappears into the weeds of all other effects on human health.

You have a great deal of faith in human institutions that bill themselves as scientific. Perhaps your faith comes from your own academic background.

I am skeptical and have a questioning attitude - remember, that is the theme of this blog. My attitude is partially based on the reverence with which people hold the "Chief Scientist" of the Rocky Mountain Institute, the scientist who publishes Climate Progress, the scientists who approved the publication of a new book about Chernobyl that is completely full of lies and falsehoods, and the "scientists" who continue to claim that a single alpha particle can cause cancer and that plutonium is on of "the most deadly substance known to man."

I am essentially a technician, not a scientist. The kinds of people mentioned above have done a lot to damage the credibility of scientists and my "faith" in their pronouncements and prescriptions. I will trust, but verify before accepting them just because they call themselves scientists or because they happen to hold a fancy sounding degree.

Rod Adams said...

This is in response to no one in particular, just another link for additional reading and later reference.

Here is a quote from this article from Asia Pacific Fire titled Selecting and Placing Gas Detectors for Maximum Application Protection.

"Consider these factors when evaluating optimal placement and quantity of gas detectors: gas or vapor source, ignition source, gas density or buoyancy, location (indoors or outdoors), ambient temperature, and personnel location.
Gas or vapor source: To locate potential gas or vapor sources, review Process and Instrumentation Diagrams (PIDs), facility maps, and hazardous-area classification drawings. Evaluate the characteristics of potential sources including pressure, amount of source, source temperature, and distance. Common areas for releases include pump and compressor seals, instrumentation sources, valve seals, gaskets, and sample points.
Ignition source: After determining the presence of combustible gas, identify sources of ignition – sparks or high-pressure gas release areas. Place the detector between the ignition source and any potential source of the gas or vapor.
Gas density, or buoyancy: Gas or vapor that is less dense than air (1.29 g/cc at normal conditions) will rise in still air. Gas or vapor that is denser than air will settle to lower elevations in still air. The detector typically should be placed 45.7 to 61 cm (18 to 24 inches) above level where the gas would settle. Remember that temperature affects the density of a gas. Heating decreases the density of a gas and makes it lighter. In fact, heating or cooling a gas by 30°C (54°F) changes the gas density by approximately 11%. Pre-stratification by thermal sources can delay or prevent gas detection near heated areas or ceilings. This typically occurs where heat sources are near the ceiling or where roof decks are heated by solar radiation and no
suitable mechanical ventilation is provided. If such pre-stratification potentials are present, then placement of the detector in area(s) unaffected by the stratification is recommended."

Rod Adams said...

Oops - the last quote should have included the next paragraph.

Indoors/outdoors: The environmental setting greatly influences vapor dispersion characteristics and gas detection ability. Typically, indoor settings mean that the overall hazardous area is well con- tained and that air flow can be identified and controlled. Ceilings and walls usually are the likely areas for gas accumulation and area delineation. Point(s) of human contact are usually identifiable. Outdoor settings mean the air flow is less control- lable with few distinct areas of gas accumulation. These areas present a challenge that requires comprehensive application analysis and sound engineering judgment.

GRLCowan said...

... into the stratosphere where they would be destroyed by UV, release free chlorides and destroy as much as 100,000 times as many molecules of O3 via a catalytic reaction.

Please correct my summary ...

Your summary is incorrect where I have bolded it. The monatomic chlorine-vs.-chloride error was the only one on which I recall any of us getting any concession, and it looks as if that might have been a token concession for the sake of appearing rational, to be -- as above -- quickly and quietly deconceded.

Who are you, and what do you know about the real Rod Adams' inability to get to his blog?

(How fire can be domesticated)

david lewis said...

Rod: I don't think your reasons to suspect all scientists add up to a solid case, judging by the names and links you provided.

Anyone should question whether Amory Lovins, self described "chief scientist" of his own institute, is a credible source of information. For one thing, Lovins spouts lies, something which can be checked by actually reading the sources of information he quotes. It would be a mistake to judge all "scientists" because of anything Lovins does, or even to go along with Lovins as he calls himself a "scientist". I thought you had checked with Harvard and Oxford and discovered that he dropped out before obtaining any degree?

Your link, I assume it was supposed to be to something written by someone claiming to be a scientist who was exaggerating the danger of plutonium, was a WikiAnswer from There was the popular gibberish about plutonium being the most dangerous substance known, but a link to further information went to a Wikipedia entry that explains plutonium in a much more balanced way. Again, I think this is insufficient excuse to criticize all scientists.

The Center for American Progress Action Fund, headed by John Podesta, who claim responsibility for the existence of the Climate Progress blog and Joe Romm, its editor, is a somewhat different kettle of fish. Romm actually did complete a PhD at MIT, and he is a Fellow of the AAAS. He admits his career is "certainly not the traditional science career". The AAAS elected him as a Fellow, in Dec 2008, "for distinguished service toward a sustainable energy future and for persuasive discourse on why citizens, corporations, and governments should adopt sustainable technologies". Given the unabashed way he lies about what is known about nuclear power, if public opinion changes about nuclear Romm's reputation will suffer. Keep in mind that anyone can set up shop and claim to be a think tank, hire someone with a PhD as one front person and claim to be dispensing scientific information that would be generally accepted by most researchers working in that particular discipline of science. Buyer beware. I wouldn't judge all scientists by what Romm does, I would tend to suspect think tanks.

The AAAS claims to be the world's largest scientific organization, but this is partially because anyone, anyone at all, can be a member of the AAAS. The "Fellows" are a more select group, but they are elected by the members, who are, as stated on the AAAS website, anyone.

The AAAS does seem to me to be a step up from the Rocky Mountain institute however. I keep in mind when thinking about Rocky Mountain, that anyone at all can set up their own shop, call it an institute, call themselves the chief scientist, and go out, like a TV envangelist, and crank out the lies at the highest volume civilization will let him get away with. The AAAS is much more substantial that that. Maybe they'll throw Romm out one day.

Your link to the webpage of the New York Academy of Sciences which featured the Chernobyl book also should not tend to bring all scientists into disrepute, in my mind. The New York Academy membership is open to anyone, like the AAAS. They distance themselves from the book by saying "nor is it a work commissioned by the New York Academy of Sciences". They do however claim to publish "content deemed scientifically valid by the general scientific community, from whom the Academy carefully monitors feedback". If the book is full of lies, contact the most reputable radiation scientists and suggest they review it for the New York Academy.

I'll continue on in the next comment.

Rod Adams said...

Interesting paper on modeling behavior of dense gases:

Apparently there is some depth of research in the field being done by the LNG industry when they study the potential hazards of leaks.

(Note: comment added for future reference during experimental design.)

david lewis said...

The National Academy is completely different. The NAS was created by Congress in 1863 and given a mandate. Almost 10% of the members of the National Academy of Sciences in the US hold the Nobel Prize. A scientist is elected to be an NAS member "in recognition of their distinguished and continuing achievements in original research". The NAS reputation is high among scientists: I don't doubt that, as the NAS website claimes: election to the Academy is considered one of the highest honors that can be accorded a scientist or engineer. The NAS was set up in 1863 to "investigate, examine, experiment, and report upon any subject of science or art". Their perceived mandate now is to "perform an unparalleled public service by bringing together committees of experts in all areas of scientific and technological endeavor. These experts serve pro bono to address critical national issues and give advice to the federal government and the public". link If the National Academy puts together a committee to assess an issue, the result becomes a touchstone in any public debate about the subject from then on. All reputable scientists would not necessarily agree with everything an NAS committee would say, but it means something when a group of the most distinguished scientists in any field come together to assess how solid and how extensive the state of scientific knowledge is that underlies an issue that has become a public concern.

And so, I point to the work of scientists publishing in peer reviewed journals, who are often but not always NAS members, and to NAS assessments, when I wish to support a case I happen to be making, for instance, that it was wise to phase out the CFCs because of fears of ozone depletion.

Rod Adams said...

@GRL - correction accepted. Chlorine versus chlorides. Please accept my apology for the typographical error. I was attempting to refer to Cl, not to ionized Cl.

I assure you that I am the real Rod Adams. Can you please explain what you meant by the following?

"Who are you, and what do you know about the real Rod Adams' inability to get to his blog?"

Have I neglected to answer a particular comment? Please understand that it is the weekend and I do have a real life.

Rod Adams said...

I just found this article tracing the history of the theories and scientific acceptance of the theory that CFCs cause stratospheric ozone depletion:

Here is another history of the issue from an organization that gives me some pause and reasons for skepticism - the Natural Resources Defense Council.

(For David Lewis, until a few minutes ago, I had not read this NRDC report, but after reading it, I have to admit that it strengthens my curiosity about the science behind the ban. The NRDC is a band of policy lawyers with strong corporate ties that employs another one of those credentialed scientists that makes me a skeptic - Dr. Tom Cochran is a virulent anti-nuke with a PhD in Nuclear Physics.)

I will also point you to the relevant pages in the NAS report on the topic issued as an update to their 1976 quick look after Rowland and Molina first published their theory in 1974. (Please notice just how quickly this all came about.)

Here is a quote from that NAS study.

Computer calculations using current understanding and incorporating new data on rates of several important reactions (Appendixes C and D) suggest that continued release of teh CFCs, CF2Cl2 and CFCL3, at rates prevalent in 1977 would ultimately cause a net decrease of total global ozone roughly between 5 % and 9% assuming no other perturbations. We regard a representative result to be 7%. This would result in a smaller steady state reduction in ozone than reported in NRC (1979b), which was 16.5% with a 95 percent probability that the true value lies between 5 and 28%.
. . .
Calculations now indicate that the reduction would occur almost entirely at altitudes above 35 km, in the region of the stratosphere where the ozone concentration is determined primarily by chemical processes, with a smaller, partially compensating increase in ozone concentrations at lower altitudes. The current result obtains for both 1- and 2- dimensional models and further differs from that prevalent in 1979 in the earlier calculations showed regions of reduction both above and below 35 km."

The summary of the NAS report titled "Causes and Effects of Stratospheric Ozone Reduction: An Update (1982)" reads quite differently from what one might understand by reading documents that point to the NAS as being strongly supportive of the effort to ban the production of CFC.

Even in 1982 - several years after the first bills were passed and the hysteria in the media had been generated to get people to stop buying aerosol cans, the NAS produced a nuanced report indicating a lot of uncertainty, but also a lot of refinement in the models that indicated that the sky was indeed, neither falling or disappearing.

I am not anti-science or anti-scientist. I am skeptical of science used to impose political and economic changes especially when lawyers like the NRDC get heavily involved. I keep asking questions and probing when the answers do not make sense. Sniff tests may not satisfy professional scientists, but people who live in the real world would be ill advised to ignore them.

Rod Adams said...

Another interesting part of the 1982 NAS report is Appendix D "The Measurement of Trace Reactive Species in the Stratosphere: A Review of Recent Results."

As a data analyst in my day job, I find the plots on the following page particularly interesting. You have to have pretty finely tuned eyeballs to see a pattern in the dots on the graphs of ClO in situ data that are published here and on the two subsequent pages.

David said...


Thank for for asking these questions and doing some digging. I have never understood this issue, that is how the science was actually concluded since it went against what I understood was happening in the creation of ozone. The answers to you have helped me understand a bit better why this was a matter of concern.

However, you are asking the right questions, and I agree with your motivation, especially making good cheap solutions available to the majority of humanity. I understand that CFC refrigerants are some of the safest, and best for compression refrigeration, as well as being the least expensive to manufacture.

A scientist who proposes a theory that has a radical impact on the economic well being of the whole world should be totally questioned. Her theory should be tested and well funded both FOR and AGAINST, until she is able to demonstrate clearly that it is correct against all comers.

I am a total lay person in this debate, but I know enough to be able to follow it. I am now convinced that CFC's can disperse into the upper atmosphere, and that they can produce a catalytic effect that has the potential to destroy some Ozone.

However, I am still wondering how, if the ozone is destroyed it is not almost immediately recreated when the intensity of the UV light increases. Your link to the NAS study saying that ozone reforms at a lower level is very close to my own simple "thought experiments" about this issue.

So, even if CFC's can destroy O3 at a stratospheric level does that mean that O3 disappears from the atmosphere? This to me is the essential question and a time lag of only two years between publication and legislation would make me suspect that this issue was not settled clearly.

It also seems clear that Antarctic is a special case and cannot be used to model any effect in the rest of the atmosphere.

To the "real scientists" who are commenting. I deeply appreciate the chemistry you are pointing out and the persistence you have in replying. Please note that well trained and intelligent people have questions about these theories. This is an indication that either the science backing them has not been clearly explained, or that there are holes that need patching.

I never forget that before Einstein it was settled science that there was a universal time coordinate. "Settled science" seems like an oxymoron to me. We have much to learn. Please look at the success of a company like Intellectual Ventures using people from a wide range of backgrounds to look at how to solve a problem.

It was a materials scientist not a battery expert that was able to rethink lead acid chemistry for Caterpillar. I wish it had not died to lack of funding. - use the way back setting to go back about a year.

I am very interested in the debate.

Michael Tobis said...

This is an old argument, and still wrong.

The atmosphere is well-mixed through the stratosphere.

Stephen Gloor said...

Just a question Rod for the Questioning Attitude.

Why is the Antarctic cooling rather than warming like the rest of the atmosphere?

Answering this question will give an insight into the ozone hole that exists over the Antarctic.

Additionally how about independent supporting evidence:

:Although increased awareness and earlier diagnosis appear to have accompanied increased incidence, increased exposure to solar UV radiation during the past 50 years appears to be the most likely explanation for the rise in incidence rates. Implications: A better understanding is needed of the causes of melanoma and of the complex relationships between constitutional factors, ambient UV radiation, and sun-exposure behavior.:

Are you questioning that CFC are the cause or that it is not happening. If you want to question the mechanism you really need an alternative. This is where the climate change deniers fall down. They have not credible alternative and neither do the LaRouche people that you seem to have attached to.

Propose an alternative theory to account for ozone depletion as independant lines of evidence point to a real ozone hole.

BTW in your part of the world it is only of academic interest. Here in Western Australia with the highest incidence of skin cancer in the world you do not have to convince many people that there is ozone depletion. Our kids are taught to slip slop slap on TV. Is that on your TV?

GRLCowan said...

Have I neglected to answer a particular comment? ... I do have a real life.

You talked about the boiling point of R-114 in a way that seemed silly to me, and did not answer my comment relating the matter to known ice and snow behaviour.

I estimated that the vertical distribution of CFCl3 in a 200-m air column was "nine at the top if it's ten at the bottom", and you quoted this answer and then, in the same posting, asked,

... will most of the material remain low, will it equally diffuse throughout the column so that the concentration at the very top is the same as the concentration at the very bottom ...

My estimate of 11 percent stratification in 200 m was the end state of either an atmosphere that starts out well-mixed, like the real one, as Michael Tobis points out, or one that starts with the CFCl3 pooled on the ground, and then, in both cases, is left undisturbed for a long time.

(How fire can be domesticated)

David said...

@ Stephen Gloor,

If the Ozone is depleting in a way that is uniform due to through mixing of the atmosphere why is Western Australia exceptional?

Rod did propose a mechanism for the depletion of ozone in the southern hemisphere. The isolation of Antarctica during the winter due to unique weather conditions.

So, respectfully, would we not consider that this Ozone depletion would affect areas like Australia and South America from a localized effect? I would turn your question "Our kids are taught to slip slop slap on TV. Is that on your TV?" back to ask, why is this not happening in other areas? I live fairly near the equator. It would seem logical that UV light would be stronger here.

The Question again is not so much do CFC's exist in the atmosphere, but do they exist in enough quantities to overcome the creation of Ozone by UV light?

I really don't understand your saying that there is no other mechanism / theory when a sufficient mechanism was pointed out for the ozone hole over Antarctic.

Stephen Gloor said...

David - "If the Ozone is depleting in a way that is uniform due to through mixing of the atmosphere why is Western Australia exceptional? "

Its not - it is near the area of depletion that extends over the Antarctic. The Antarctic is cold and dry both conditions lead to more erosion of ozone than in other areas. Also the Antarctic is surrounded by what amounts to a wall of wind trapping the CFCs which isolates it.

"Rod did propose a mechanism for the depletion of ozone in the southern hemisphere. The isolation of Antarctica during the winter due to unique weather conditions. "

No he didn't. This is not a reason in itself but leads to more effective depletion of ozone by the CFCs. Without the CFCs the ozone level over the Antarctic would be quite normal.

" I live fairly near the equator. It would seem logical that UV light would be stronger here. "

If you are in the Northern Hemisphere then the depletion is not as bad. If you live near the equator you would not have the depletion zone going over you like we do here.

"The Question again is not so much do CFC's exist in the atmosphere, but do they exist in enough quantities to overcome the creation of Ozone by UV light? "

Yes they do as the depletion has been measured and mapped. The mechanisms have been identified and proven in the laboratory. The gases have been measured where they are doing the most damage. What more do you need?

Rod Adams said...

Here are some additional resources that might be useful in future modeling and discussion.

It turns out that there has been a substantial amount of work done on the behavior and modeling of heavier than air gases in the years since the ban on CFCs. These studies have not focused on CFCs, but on gases like CO2, propane, LNG and chlorine that have the potential for posing significant harm if "spilled", especially if the first responders do not understand how they will spread react to outside influences like wind, obstructions and depressions or valleys.

Here is a paper about modeling CO2 concentrations in an area of Italy where there are several natural vents -

One interesting part of that was the way that the model predicted, and actual experience demonstrated, that there was a greater threat to small animals who breathe at 0.1 meters above ground level compared to humans who breathe at about 1.5 meters above the ground.

"The model predicts that under this condition, the CO2 concentration at 0.1 m height reaches maximum values of about 7% in an area near to the vent. These values indicate that concentrations of the order of 10% can be reached near the soil defining a potentially lethal region for small-size animals for exposures longer than 10-15 minutes (see Table 1). Moreover considering that at CdM H2S constitutes ~ 1.2% of the gas emission and assuming the gas plume maintains a CO2/H2S ratio close to the original value, a concentration of about 5.5% of CO2 would imply a
near lethal H2S concentration of 700 ppm (Beaubien et al., 2003).
At 1.5 m height the model finds a maximum CO2 concentration of about 3%, a value below the 5.5% threshold defined on the basis of the H2S concentration and well below the pure CO2 dangerous threshold for humans of 15% (Table 1). These results generally agree with the fact that at CdM accidents to humans were never recorded whereas some times small size animals killed by the gas were found."

Here is another one - "CFD prediction of dense gas clouds spreading in a mock urban environment"

Here is an interesting sample quote:

"Initially, it was presumed that dense gases would disperse in a manner similar to neutrally buoyant mixtures; however, accident experience with spills of ammonia, LNG, propane and other heavy gases revealed this was not the case. Dense gas clouds collapse under the effect of gravity, move upwind against low near ground level winds, and spread laterally in a pancake like manner. Hence, in the 1970s research programs were initiated to examine dense cloud/plume behavior both in the field and the laboratory."

David said...

@ Stephen Gloor,

I don't know if you are still monitoring this, but thank you very much for your response. It is helpful. I am sorry to be obtuse here but I am still a bit confused.

You said,

"No he didn't. This is not a reason in itself but leads to more effective depletion of ozone by the CFCs. Without the CFCs the ozone level over the Antarctic would be quite normal."

So you are saying (claiming?) That this Ozone hole did not exist before the use of CFC's and that the weather conditions in the Antarctic were not sufficient to produce the lack of ozone on their own?

My difficult is that your statement that in other areas the Ozone is about normal levels seems to support the unique situation of the Antartic. Please forgive me for begin confused here but it seems that if there are historical records that indicate an ozone hole before the production of CFC's that would indicate a mechanism sufficient to account for the problem in the Antarctic.

Has any historical research been done in South America or in Australia to demonstrate this is truly a modern phenomenon? I ask this because I remember reading accounts of cattle dying in South America well over 100 years ago. I don't have references, it has been at least 20 years since I read that.

david lewis said...

Sherwood Rowland, quoted from "President's Lecture: The Need for Scientific Communication with the Public", Science; Jun 11, 1993; 260, 5114; Platinum Periodicals pg. 1571.

"Most scientists know that gravity acts in proportion to the molecular weight of molecules, with the result that those which are heavier than air tend to sink toward the floor when released in a quiescent laboratory. This well-known circumstance often leads the newcomer to atmospheric problems - many of my fellow chemists, for example - toward the conclusion that a heavier molecule, such as the chlorofluorocarbon trichlorofluoromethane - also known as CFC-11, with molecular weight 137.5, almost five times as heavy as air - would have great difficulty reaching the upper atmosphere. In the more radical but sometimes asserted hypothesis, such heavy molecules could never penetrate into the stratosphere.

The atmosphere, however, is not a quiescent laboratory, and its mixing processes are dominated to altitudes far above the stratosphere by the motions of large air masses which mix heavy and light gaseous molecules at equal rates. Throughout most of the atmosphere, all gaseous molecules go together in very large groups, independent of molecular weight. The first experiment which began to provide information along this line was carried out in 1804 by two French scientists, Gay-Lussac and Biot. That the atmosphere mixed in the fashion was already well established 25 years ago prior to any measurements of CFC-11 or any other halocarbon in the stratosphere 1. When CFC-11 was first detected in 1970 in air samples collected at the Earth’s surface, it was therefore logical to assume that such molecules would soon begin to penetrate into the stratosphere as well.

By 1975, stratospheric air samples had been obtained with both balloon and aircraft platforms and had been shown regularly to have CFC-11 present in them. During the past 17 years, CFC-11 and more than a dozen other halocarbons have been measured in literally thousands of stratospheric air samples by dozens of research groups all over the world.

Naively, one might assume that the transport of CFC-11 to the stratosphere would now be a fact accepted by all scientists. Not so. A scattering of letters and articles by persons identifying themselves as scientists continues to be printed in scientific news magazines or other major media which say that (1) molecules such as CFC-11 cannot reach the stratosphere because they are much heavier than air, and (2) no measurements have been made that show the CFCs to be present in the stratosphere (2-4) . Scientific progress is usually described as occurring through the formulation and testing of hypotheses, discarding those that fail to meet the test of observation. What is not so often remarked upon is the reluctance which many have to accept the results of observation, or even to bother determining whether any pertinent observation have been made….

Footnotes for this exerpt follow in the next comment.

david lewis said...


1. “U.S. Standard Atmosphere, 1962” National Oceanic and Atmospheric Administration, National Aeronautics and Space Administration, U.S. Air Force, Washington, DC (1962); “U.S. Standard Atmosphere, 1976”, National Oceanic and Atmospheric Administration, National Aeronautics and Space Administration, U.S. Air Force, Washington, D.C. (1976).

2. “CFCs are heavy, complex molecules. There has yet to be published a single scientific paper which presents any documented observations of large numbers of these molecules rising to the stratosphere. It is especially difficult to see how they can rise as high as 30 km, where the greatest concentration of ozone is located. Present claims are based solely on the supposition that CFCs will rise to the stratosphere because they are not water soluble molecules” [R. Maduro, Exec. Intell. Rev. 27, 18 (1989), p. 19]

3. “Incidentally, CFC molecules are heavier than air, and their concentration in the upper atmosphere at extremely low temperatures must be infinitesimally small” (R.A. Beck, Chem. Eng. News, 26 June 1989, p. 62, “Since CFCs are heavier than air, how do they get into the stratosphere in quantities large enough to cause ozone depletion? …If CFCs are responsible for the destruction of the ozone layer, why has their presence never been detected in the stratosphere?” (R.S. Bennett, Wall Street Journal, 25 March 1993, p. A15)

4.“How does CFC rise when its molecules are four to eight times heavier than air? All experience with Freon and related CFCs shows that they are non-volatile and so heavy that yhou can pour CFCs from a container and if some of them spill, they will collect at the lowest point on the ground, where soil bacteria will decompose them. Of course some molecules will be caught in upward air eddies or otherwise carried upwards, but this is a very small fraction of the total” [D.L. Ray and L. Guzzo, Environmental Overkill (Regnery Gateway, Washington, D.C. 1993), p. 35]; “As already pointed out, CFC molecules are (depending on which CFC is considered), four to eight times heavier than air molecules; most CFC that escapes into the atmosphere falls to the earth. There soil bacteria decompose CFCs within a few days or weeks” (Ibid., p. 47)

Hank Roberts said...

Rod, let me suggest a couple of examples where you misstate the physics, followed by information you can find in Rowland's Nobel Lecture in Chemistry

You wrote:
> sinks ... sumps ...
> gravity ... density


"... present in the Earth’s atmosphere in quantities roughly comparable to the total amount manufactured up to that date....
... In 1974, we calculated the vertical profile to be expected for CCl3F in the stratosphere, using several different sets of eddy diffusion coefficients ..."

You wrote:

> the [ozone] production factor is
> essentially zero for several
> months while the decomposition
> factor remains.


"... absorb UV radiation at wavelengths < 220 nm, but to encounter such solar radiation in the atmosphere the molecule must first drift ... roughly to 25 or 30 km.... In this rarefied air, the CFC molecules are exposed to very short wavelength UV radiation and decompose .... Because at any given time, only a very small fraction of CFC molecules are found at altitudes of 30 km or higher, the average molecule survives for many decades before it is decomposed by solar UV radiation."

Hank Roberts said...

Rod, I think you'd find this book rewarding:"Ozone%2BLayer"%2B"philosophy%2Bof%2Bscience"

This explains what I think you'll find very helpful about the book:

Hank Roberts said...

This may help, as an example of how a skeptic investigates an area where he has a strongly held belief, trusting only his own work, and proves himself wrong and changes his mind:

OCTOBER 21, 2011

The Case Against Global-Warming Skepticism
There were good reasons for doubt, until now.


Hank Roberts said...

this may help explain the timing -- why ozone goes away when the sunlight returns:
Ozone-forming and ozone-decomposing reactions are summarized i

Hank Roberts said...

Did you get any further with this?

The best reassurance someone like you can offer those who worry about industry is to say, "ya know, I read more about this since then, and talked to more people who had better information, and thought about who I was trusting and their agenda, and after that, my opinion changed a bit, and now, I think ....."

Rod Adams said...

Hank - What makes you think that my questions on this topic were influenced by anyone's agenda?

The only people I am trusting on the issue of whether or not CFCs sink or risk is my own experience of tracing their behavior inside a well mixed, but isolated atmosphere inside a submarine.

That behavior is validated by the material safety data sheets that warn practitioners about the way that the gas pools in low spots in basements and subterranean areas.

Though I still do not have the resources required to mount a substantial challenge to the conventional wisdom, doing so with well designed experimentation remains on my bucket list.

Hank Roberts said...

Ah, OK. I'm an old guy, I was reading the ozone story when it first came out and have watched it since. And I've seen the "heavy, sinks ..." argument made over all those years -- so I guessed you'd come across it somewhere and thought it sounded credible.

You can look this stuff up, and I trust you will. Basically, I'll predict you'll find that you're surprised (and that I'm not).

I expect -- amateur paraphrase from memory here -- that you'll find that in actual observation, while in a closed environment heavy gases will pool at low points for a period of hours or even days, diffusion overcomes gravity even there; and in the open air, diffusion aided by air circulation overcomes gravity quickly. That's why so many fairly large molecules are well mixed gases in the atmosphere.

After that, what counts for CFCs is their incredible stability, which allows significant amounts to be transported to the stratosphere before they get broken down

We don't all suffocate from the layer of CO2, which some have argued would settle out in the low places. Yet the Dead Sea is still a popular beach, and Death Valley still, well, alive.

It's not intuitive. And contrariwise, people do die every year in caves, and big fuel or distillation tanks, because they do go into spaces full of heavy gas that's displaced the oxygen, because diffusion rate isn't intuitive on either side.

I came back thinking about this after posting elsewhere something relevant, a bit wordy but there's just the two of us here (grin). This was replying to a comment by John Quiggin. Others have made the same point -- to beware of those "on our own side" politically, if we can stand to be outside those chummy groups that all agree on how the world should be despite evidence.

-- what I wrote elsewhere:

Quiggin's right: the people to (provisionally) trust are those -- of any political persuasion -- who are "seeking to dissuade their own side from tribalist and anti-science rhetoric" -- and do that first.

It's damned rare behavior, and rarely rewarding personally. So it goes.

This is why I have respect for a diverse and often mutually incompatible group of people I'd like to consider friends -- people who struggle with themselves, and with their compatriots, before going out to improve everyone else's thinking.

And ya know what? Feedback from those folks -- whose politics are all over the map -- is worth serious attention, because they make the effort so when they come to correct me, I can (provisionally) think they've probably thought the point through before bringing it up.
an example from a while back of an old friend, a crop scientist, making a valiant effort to educate the "environmentalists" --

---- further comment ----
7 years later, there's still an ethanol industry, still trying to fake up science to justify finding new feedstocks for their refineries and continued growth, but -- the science is against them.

And, aside, there's still new science coming out about how the atmosphere works:

Crutzen, in his speech accepting the Nobel Prize for the earlier ozone research, commented that we'd dodged a bullet because industry could have chosen bromine instead of chlorine as the formula for the newly invented super stable fluorocarbons -- chlorine was marginally cheaper at the time (and bromine turned out to be far more dangerous, but nobody would have known that til way too late -- and now, bromine turns out to be more of a risk than he imagined, too)
Best to ya.

Hank Roberts said...

Oh, these searches -- done in Google then in Scholar -- find pretty much the information I rely on. Your observation -- in the situation where you made them, over the time span you made them -- that heavier gases do sink, for a while -- is correct. In the atmosphere, over a period of a few years, no.

Note in the ocean mixing takes longer -- and these are very useful tracers for ocean circulation over recent decades, as we know pretty well when each was invented and how much was released. That's another search tho'.

Rod Adams said...

Hank - the flaw in the assumptions made by Rowland is that the places where CFC's were leaked are not actually very open air.

Nearly all CFC containing systems operate at or below ground level and they operate in places where people live and have built basements, sewers, and trenches and where nature has carved valleys and pits.

There are many low circulation areas on the earth that are analogous to the bilges that we had on submarines. I was the engineer on a submarine with a significant leak in an R-114 air conditioning unit. Essentially all of the refrigerant that leaked out sank to the bilge and stayed there. It did not diffuse.

Like many who have argued with me on this topic, you point to CO2, but the molecular weight of CO2 is within about 20% of that of N2 or O2. In contrast, most CFC's are 5 times as heavy as N2 gas.

Another thing that most observers miss is the fact that CFC's will decompose if they are sucked into a furnace or internal combustion engine. Most of those are conveniently located in those same populated places where CFC systems are located.

One more thing - most of the CFC's that were produced were working fluids in systems that operated for many years without any new fluid injected. In other words, they are designed to be sealed, not to continuously discharge into the atmosphere.

Hank Roberts said...

But, Rod, they're out there:

The exceptional stability of these compounds is the key here.

You didn't believe they'd diffuse -- but the're observed in the stratosphere, so they do get there.

You don't think they could be a problem, but they're known to be.

They survive long enough to reach the stratosphere and even there survive long enough to catalyze ozone breakdown.

The argument from incredulity -- that little bit can't possibly be bad -- doesn't work here.

Seriously, read Crutzen's Nobel acceptance speech, I'm sure I linked it.

Hank Roberts said...

This may help, since Rod asked why the chemists started looking:

Hank Roberts said...

Rod, to sum up -- I like what you do, but you're basically arguing that what the physicists and chemists say can't possibly be right because, uh, you can't believe it, because, uh, it can't possibly be right, because -- this is the key -- because it's such a little tiny small minute effect how could it matter?

And the answer from the physicists and chemists is -- it matters a lot.

Here's the reason I, and I think others, are persisting in trying to patiently talk you through paying attention to what the physicists and chemists are saying is dangerous:

You operate a nuclear fission plant.

If you, the guy operating a nuclear power plant, believe firmly that what the physicists and chemists agree is dangerous just couldn't possibly be because it's such a small effect -- then people have a right to be scared of guys who operate nuclear power plants.

Seriously -- you know Ken Thompson on trusting trust?

You want to be trustworthy.

You ought to be trusting the physicists and chemists on this.

Logic is not your friend here.

Measurement is.

All your arguments make sense except the last one -- because enough of the CFCs reach the stratosphere that the problem happens.

Just a teeny tiny little amount.

Think about this.
When a nuclear plant operator says "I can't believe that little bit of stuff could be a problem" -- who should people trust?

Give us an example of changing your mind after reading the published science.

Hank Roberts said...

see also:

Hank Roberts said...

This may help -- I'm taking the people who do the calculations for kinetic gaseous diffusion at their word; there are enough decades of work done and enough measurements, I think, to confirm theory and practice give the same answer on it.

The first result is

Chlorofluorocarbons and the Depletion of Stratospheric Ozone
F. Sherwood Rowland
American Scientist
Vol. 77, No. 1 (January-February 1989), pp. 36-45
Published by: Sigma Xi, The Scientific Research Society
Article Stable URL:

The excerpt Scholar gives includes this: your question "... posed by
laboratory-boundscientists is, How can molecules which are much heavier than air ... answer is
that indoor experience with mass-dependent molecular diffusion is not applicable ...."

You know that in an enclosed container, people can suffocate from CO2, or even nitrogen -- which we know are light and readily mixed gases. Diffusion takes time. Chlorofluorocarbons, being very stable, last long enough to diffuse and reach the stratosphere.

Hank Roberts said...

Chlorofluorocarbons have been measured, as has the chlorine released from those very stable molecules when they finally do break down in the stratosphere. Control on producing and releasing the CFCs, reduction in the amount measured.

Nature Communications 6,Article number:7233

"... Chlorine- and bromine-containing ozone-depleting substances (ODSs) are controlled by the 1987 Montreal Protocol. In consequence, atmospheric equivalent chlorine peaked in 1993 and has been declining slowly since then...."

Big stable molecules do diffuse in open air, and end up high in the stratosphere.
Thinking they can't do that doesn't stop that from happening:

"CFC molecules are indeed several times heavier than air. Nevertheless, thousands of measurements from balloons, aircraft, and satellites demonstrate that the CFCs are actually present in the stratosphere. This is because winds and other air motions mix the atmosphere to altitudes far above the top of the stratosphere much faster than molecules can settle according to their weight. Gases such as CFCs that do not dissolve in water and that are relatively unreactive in the lower atmosphere are mixed relatively quickly and therefore reach the stratosphere regardless of their weight.
"Measured changes in the concentration of constituents versus altitude teach us more about the fate of compounds in the atmosphere. For example, the two gases carbon tetrafluoride (CF4, produced mainly as a by-product of the manufacture of aluminum) and CFC-11 (CCl3F, used in a variety of human activities) are both heavier than air.
Carbon tetrafluoride is completely unreactive at altitudes up to at least 50 kilometers in the atmosphere. Measurements show it to be nearly uniformly distributed throughout the atmosphere (as illustrated in the figure below, the abundance of CF4 is nearly the same at all altitudes where measurements have been made). There have been measurements over the past two decades of several other completely unreactive gases, both lighter than air (neon) and heavier than air (argon and krypton), that show that they also mix upward through the stratosphere regardless of their weight."

Hank Roberts said...

Still going as expected:

"... This year, scientists recorded the minimum thickness of the ozone layer at 101 Dobson units on October 4, 2015, as compared to 250-350 Dobson units during the 1960s, before the Antarctic ozone hole occurred. Dobson units are a measure of the overhead amount of atmospheric ozone.

The satellite ozone data come from the Dutch-Finnish Ozone Monitoring Instrument on NASA's Aura satellite, launched in 2004, and the Ozone Monitoring and Profiler Suite instrument on the NASA-NOAA Suomi National Polar-orbiting Partnership satellite, launched in 2011. NOAA scientists at the South Pole station monitor the ozone layer above that location by using a Dobson spectrophotometer and regular ozone-sonde balloon launches that record the thickness of the ozone layer and its vertical distribution. Chlorine amounts are estimated using NOAA and NASA ground measurements and observations from the Microwave Limb Sounder aboard NASA's Aura satellite. These satellites continue a data record dating back to the early 1970s."

Hank Roberts said...

"This is indeed a persistent question--so much so that the most recent report of the World Meteorological Organization, entitled 'Scientific Assessment of Ozone Depletion: 1994,' included it among a list of common questions that have been persistently raised and long since answered. Susan Solomon of NOAA Aeronomy Laboratory in Boulder and I are listed in the document as the Coordinators of Common Questions about Ozone. We had as many as 22 of them, but pared them down to the most frequently asked ones.

"The response to this particular question reads as follows."

Although the CFC molecules are indeed several times heavier than air, thousands of measurements have been made from balloons, aircraft and satellites demonstrating that the CFCs are actually present in the stratosphere.....


Seriously, people who run fission plants can't afford to ignore the science and engage in wishful thinking about physics.
Personal experience in a submarine isn't evidence about how the atmosphere works.

Rod Adams said...

I'm fully aware that CFCs "have been measured." The concentrations at which they have been measured at elevated locations in the atmosphere are several orders of magnitude too low to account for the amount of claimed reactions with ozone.

When I point out that fact, the general response has been "Of course, that is because they have already been decomposed and reacted with ozone."

That is a circular argument.

My contention is that there are plenty of other decomposition reactions in the ground level environment that account for the amount of CFC that has been leaked into the atmosphere without postulating that it all floated up and destroyed ozone.