Were world leaders misled when they decided to ban CFCs?
Every once in a while, I write up an observation or thought that cannot be directly related to the kinds of energy discussions appropriate for Atomic Insights. I occasionally publish those observations on a separate blog called Questioning Attitude that is named after one of the life philosophies that Admiral Rickover encouraged in his nuclear trained personnel. In letter after letter, Admiral Rickover reminded his people to maintain a questioning attitude and told us that the worst excuse for doing something illogical was “it has always been done that way.”
My most recent publication on Questioning Attitude is titled It is probable that atmospheric scientists were wrong about CFC’s. In that article, I trace through, in as brief a way as possible, the genesis of my assertion that CFCs do not destroy the ozone layer – even though Nobel Prize winning scientists asserted that they do and that most of the world’s leadership voted to agree with that assertion.
For the past several weeks, I have been engaged in an email conversation with a guy who was actively involved in the effort to ban CFCs. He has repeatedly accused me of being a science denier. I think there were probably several other accusations as I persisted in providing my evidence – which he described as unsubstantiated and non peer reviewed.
I finally decided that it was time to share my thoughts with a broader audience and see if my theories and supporting evidence can withstand the onslaught of commentary that might result. If you have any thoughts on the matter, please add them in the comment section on that Questioning Attitude blog post instead of putting them here. That way, it will be easier to consolidate them for an updated version at a later time.
Rod, just look at your own article and the Cl/O3 and ClO/O reactions.
Once formed in the stratosphere, Cl radicals are NOT consumed by the reaction. They are constantly regenerated by this cycle. The radicals are catalysts. You even use the term. It only stops when the radical is consumed by a side reaction, assuming this side reaction creates a stable chlorinated compound that will not yield a Cl radical again under UV irradiation, otherwise the cycle starts again.
So a single radical can go on and on and on to wreck destroy O3/O pairs back to O2. A single radical can go on to destroy 100 of thousands of O3 molecules. Assuming 100,000 x, it takes only 10 pptv of CFC can destroy 1 ppmv worth of ozone, given enough time.
As the CFC presence at high altitude, the assumptions I presume are used for the vapor-air mixture article (non-ideality, displacement of one specie by the other) are not applicable to very dilute additions in a gas. At very low concentrations, I’d think good ol’ Fick’s law of diffusion applies.
Actually, even simpler:
http://www.chemistryquestion.com/English/Questions/ChemistryInDailyLife/37c_mixture_atmosphere.html
The composition of the earth
“given enough time”
Well, that’s the rub, isn’t it? Got any reaction rates?
Until you’ve specified the production rate of ozone, the depletion rate of ozone from other causes, the production/depletion rates of Cl radicals, and the reaction rate of the process that you mention, you have told us nothing substantial.
@Fraikel – Sure, a single radical can go on to destroy hundreds of thousands of O3 molecules – in theory. Why stop there? Why not propose that a single radical – since it is not destroyed in the reaction – can destroy millions, billions or trillions of O3 molecules. Of course, you could also go the other way and say that in a certain period of time, with a certain rate of movement, a single radical can only destroy tens, or hundreds or thousands of O3 molecules before the clock expires.
When there is such a wide range of possibilities, the rate at which the reaction occurs in the conditions where it occurs really matters.
It’s not a matter of “proposing” but rather careful calculation of reaction networks from experimentally determined parameters. Harold Johnston, Mario Molina, and others have contributed to this. As you say, these rates and the networks of relevant reactions really matter. You might consider the work that has been done in this area.
“Why not propose that a single radical – since it is not destroyed in the reaction – can destroy millions, billions or trillions of O3 molecules.”
Because the x100,000 order of magnitude and a 2 years lifetime for Cl
@Fraikel – you wrote: “Because the x100,000 order of magnitude and a 2 years lifetime for Cl
Rod,
The X axis units are absolute concentration in molecules/cm^3. And no, the data set is not particularly noisy given the method, the state of the art at the time (remember how computers looked like in 1982 ?) and the very low concentrations measured.
Actually, that’s the rather healthy point of the article : how to correlate very disparate, huge data sets taken under wildly different conditions.
My bigger issue with the CFC ban is the extreme nature of it. My wife can no longer get a CFC-based asthma inhaler. And at 38,000 feet, I want the best engine fire suppressing agents on the face of the earth, not some second-rate substitute. Lastly, the change-out of CFC blowing agents for shuttle external fuel tank insulation nearly caused a disaster after popcorning and shotgunning the underside of the shuttle.
The bottom line has to be that anything to do with life safety or human health has to take priority over environmental concerns. The use of halons and the use of CFCs as aerosol propellants for drugs are uses that are appropriate to allow continued production for, just as, for instance, the use of DDT for health-related insect control purposes is appropriate.
Once again, the problem is not so much the appropriate use of CFCs for purposes where they are truly necessary – but their reckless consumable use (e.g. making styrofoam peanuts, as hairspray propellants, etc.) – which was stopped as alternatives became available.
(This is assuming the “ozone depletion by CFCs” theory is accurate. Based on what I understand, I believe that it is.)
@Dave – I agree with your measured approach, but I would add air conditioning and refrigeration as applications where low cost CFC’s with very light administrative controls are also life giving applications that have little possibility of environmental harm. The volume of material released into the atmosphere by these uses is naturally pretty small since the material is sealed inside machinery that will no longer work if the CFCs leak out.
For those people around the world who live on far less resources than the average American, access to cheap air conditioning and refrigeration can make life a lot healthier and pleasant, just like access to cheap energy.
There are many options to CFC’s for blowing materials, so I really have no beef with halting the use of the material in aerosol cans or styrofoam peanuts as a precautionary measure. I do believe that the hypothesis of whether or not the material actually tends to sink or float and whether or not there are sinks besides stratospheric decomposition can be tested pretty readily. There is no real economic motive for the test – after all, cheap CFC’s primarily benefit poor people.
That may be one of the reasons that I am so interested in following up with some physical experimentation.
“I do believe that the hypothesis of whether or not the material actually tends to sink or float and whether or not there are sinks besides stratospheric decomposition can be tested pretty readily.”
If CFC vapour behaves anything like all other gases of high molecular mass(mercury vapour, sulfur hexafluoride and so on) the first one is pretty easy to answer.
In bulk amounts it is dense and sinks to the floor. This is also a trivial consequence of the ideal gas law which is a good approximation at STP:
pV = nRT
If you hold p and T constant you see that the volume is directly proportional to the amount of substance. Since the molecular mass is much higher than for air molecules, a mole corresponds to a larger mass than for air and hence the gas is denser than air.
But that’s only how concentrated bulk amounts behave. At the boundary between the CFC vapour and regular air there is diffusion. At any normal temperature individual air molecules are going at hundreds of meters per second and with this intense jostling air molecules penetrate into the CFC vapour and vice versa.
Once you have individiual molecules of CFCs at low concentration in air they stay suspended; the tiny effect of gravity is overcome by the intense moshpit of air molecules and the resulting motion is brownian. It no longer sinks or floats(on average, individual molecules could go either way), it just slowly mixes evenly in the rest of the atmosphere.
CFC concentration has been measured at different altitudes and it is consistent with little or no CFC being destroyed before it diffuses into the upper atmosphere, where it can destroy ozone. CFCs also diffuse down into caves and into all sorts of other places, but nobody cares because it doesn’t directly hurt plant nor animal.
@Soylent – Here is the phrase that keeps coming up, but which I have not yet been able to accept without some quantification:
CFC concentration has been measured at different altitudes and it is consistent with little or no CFC being destroyed before it diffuses into the upper atmosphere, where it can destroy ozone.
The total cumulative amount of CFC’s produced as of the mid 1990s was just 25 million tons. (That compares with the fact that humans are dumping approximately 20 BILLION tons of CO2 into the atmosphere every single year.)
What portion of the gas floated up vice spread out and sank to low level areas? How much was measured in the upper levels of the atmosphere and what were the error bars in the measuring device? All I have read indicate levels measured in units of parts per trillion. (One molecule out of 10^12 molecules.) What kinds of devices can actually measure with that precision and what kinds of sampling techniques can capture a representative quantity of air without any contamination that might alter the measurements?
Are we really sure that there are no sinks for the material? Again, the assumption stated in Rowland and Molina’s paper was that essentially all of the material made it to the stratosphere to be destroyed. Are the conclusions still valid if the real portion that makes it up that far is only 10%, 1% or even 0.01%?
Were the samples that have been used as the basis for decision making validated by repetition? I know I am not a scientist, but I do know that repeatability is an essential quality of any valid experiment. If the results cannot be repeated by almost any qualified, independent experimenter, they are unlikely to be valid.
>What portion of the gas floated up vice spread out and sank to low level areas?
Rod, do a simple experiment. Put some sugar in a glass of water. Keep the glass very still. After a while, you will see lines that look like internal ripples as the sugar dissolves. The sugar is mixing into the water. Sugar is denser than water, but it rises into the water. After a while, stick your finger in the top of the container and taste it. It will be sweet from the sugar.
Gases are completely miscible, so you’re not even dissolving a solid in a liquid; it’s much easier for them to mix.
As to the rest of your questions, they are answered in the scientific papers that you haven’t checked out. I haven’t looked at Rowland and Molina’s papers lately, but I’ll bet that what you call an assumption is in fact a conclusion.
Cheryl – would it be possible for you to stop talking down to me? Just curious.
The experiment that you propose is to put sugar into solution – solutions behave differently than mixtures.
Gases are miscible, but not instantly. It is also well known that the rate at which they mix is related to the density of the gas.
I have read a number of the papers associated with the theory that CFCs are the primary source of ozone destruction in the stratosphere. I keep tripping over phrases like “given enough time”, “have been measured”, and “essentially all of the gases rise” that seem to conflict with the material safety data sheets that you can find for nearly every heavier than air gas that is used in an industrial environment. Those sheets warn operators that heavy gases tend to accumulate in low lying areas and voids.
Obviously my questions are not up to your standards, but they are real questions generated out of real observations. I have seen gases with different densities stratify and remain stratified for a considerable period of time – at least several days.
Yes, gases mix. In a small enough volume they mix nearly perfectly – albeit at a given rate that depends on the density of the gas, the temperature and the external influences on the motion of that gas. An atmosphere that has a depth of 15-30 km spread out over a globe with a diameter of 8,000 miles is not exactly a small volume, especially when the total mass of material under discussion is measured in tens of millions of tons.
Rod, there is too much about thermodynamics and the scientific method that you don’t understand. You haven’t done the proper calculations to support your hypotheses. You haven’t read the papers, and you make assumptions about what is being said in them that can’t be supported. You don’t know what a phase diagram is or how to use it. You confound variables (the size of a volume, for example, has no bearing on mixing, and solutions *are* mixtures!). You have no concept of molecular motion and how it affects mixing. Or at least I infer all those things from your statements.
Yes, mixing in the atmosphere is imperfect, but have you ever been in a hurricane? Or even the everyday wind cycle? You may think that my sugar experiment is talking down, but it’s an easy way to see the Second Law applied to mixtures in action. If “solutions are different from mixtures,” then tell me why.
You’re dealing in qualitative terms with things that can be calculated to see if your qualitative hypotheses are correct. The calculations, experiments, and observations have been done on the other side of the argument. You present nothing but your intuitions. At least back them up with calculations.
Or here’s the Second Law in qualitative terms: things tend toward a state of maximum disorder. Use that to explain how those nefarious CFCs are going to hide out somewhere!
I’ve been following Rod’s instructions to discuss this at Questioning Attitude. If anyone thinks I’ve been doing a good job, tell it to the tip jar.
Rod,
I’ve been following this fairly closely, and sorry to say, I think that your whole stance towards CFCs reminds me of another commentator I listen to (and enjoy quite a bit) – Bill Maher.
Mr. Maher has quite a few incisive points to make about human stupidity and insanity, in particular the effects that organized religion can have on people (ie: tend to make them batshit crazy – see religulous for a particular example). He has, generally, a very rational view towards science and the scientific method.
But when it comes to immunology – and vaccines – his views go right off the wall. He advocated a boycott of vaccines for god-knows-what reason, but it was NOT scientific but personal, highly influenced by his dislike of institutions and possibly personal experience.
Now in this case, perhaps your ‘fever’ is not quite as bad as Mr Maher’s, but I present 3 points here:
* a plausible mechanism for ozone depletion has been presented via CFCs and the general properties of gases.
* when CFCs were being produced, there was a substatnial ozone hole.
* after CFCs were banned, this hole has gotten substantially smaller.
Now, I know about ‘correlation being not equal to causation’, but in my mind a substantial amount of work has been done here, and the CFC ban/corresponding ozone-layer-healing seems to be more than a coincidence. Given the negative effects of not having a reliable ozone layer being so huge, I don’t know if I would run the CFC experiment again on our environment. I’d also like to hear an alternate explanation of this – if it wasn’t CFCs, what exactly was it that caused the ozone hole?
Anyways, it may be worthwhile to piggyback on the climate models – given that the state of the art in computer modeling is so much greater than it was then – and see how modest CFC production for critical human needs would effect the ozone layer.
But using it as a standard industrial component seems pretty dangerous to me.
Ed