(Note: this originally published on Dr. Spencer’s blog on April 25th, and I asked if I could reproduce it here. While I know some readers might argue the finer points of some items in the list, I think it is important to keep sight of these. – Anthony)
by Roy W. Spencer, Ph. D.
There are some very good arguments for being skeptical of global warming predictions. But the proliferation of bad arguments is becoming almost dizzying.
I understand and appreciate that many of the things we think we know in science end up being wrong. I get that. But some of the alternative explanations I’m seeing border on the ludicrous.
So, here’s my Top 10 list of stupid skeptic arguments. I’m sure there are more, and maybe I missed a couple important ones. Oh well.
My obvious goal here is not to change minds that are already made up, which is impossible (by definition), but to reach 1,000+ (mostly nasty) comments in response to this post. So, help me out here!
1. THERE IS NO GREENHOUSE EFFECT. Despite the fact that downwelling IR from the sky can be measured, and amounts to a level (~300 W/m2) that can be scarcely be ignored; the neglect of which would totally screw up weather forecast model runs if it was not included; and would lead to VERY cold nights if it didn’t exist; and can be easily measured directly with a handheld IR thermometer pointed at the sky (because an IR thermometer measures the IR-induced temperature change of the surface of a thermopile, QED)… Please stop the “no greenhouse effect” stuff. It’s making us skeptics look bad. I’ve blogged on this numerous times…maybe start here.
2. THE GREENHOUSE EFFECT VIOLATES THE 2ND LAW OF THERMODYNAMICS. The second law can be stated in several ways, but one way is that the net flow of energy must be from higher temperature to lower temperature. This is not violated by the greenhouse effect. The apparent violation of the 2nd Law seems to be traced to the fact that all bodies emit IR radiation…including cooler bodies toward warmer bodies. But the NET flow of thermal radiation is still from the warmer body to the cooler body. Even if you don’t believe there is 2-way flow, and only 1-way flow…the rate of flow depends upon the temperature of both bodies, and changing the cooler body’s temperature will change the cooling rate (and thus the temperature) of the warmer body. So, yes, a cooler body can make a warm body even warmer still…as evidenced by putting your clothes on.
3. CO2 CANT CAUSE WARMING BECAUSE CO2 EMITS IR AS FAST AS IT ABSORBS. No. When a CO2 molecule absorbs an IR photon, the mean free path within the atmosphere is so short that the molecule gives up its energy to surrounding molecules before it can (on average) emit an IR photon in its temporarily excited state. See more here. Also important is the fact that the rate at which a CO2 molecule absorbs IR is mostly independent of temperature, but the rate at which it emits IR increases strongly with temperature. There is no requirement that a layer of air emits as much IR as it absorbs…in fact, in general, the the rates of IR emission and absorption are pretty far from equal.
4. CO2 COOLS, NOT WARMS, THE ATMOSPHERE. This one is a little more subtle because the net effect of greenhouse gases is to cool the upper atmosphere, and warm the lower atmosphere, compared to if no greenhouse gases were present. Since any IR absorber is also an IR emitter, a CO2 molecule can both cool and warm, because it both absorbs and emits IR photons.
5. ADDING CO2 TO THE ATMOSPHERE HAS NO EFFECT BECAUSE THE CO2 ABSORPTION BANDS ARE ALREADY 100% OPAQUE. First, no they are not, and that’s because of pressure broadening. Second, even if the atmosphere was 100% opaque, it doesn’t matter. Here’s why.
6. LOWER ATMOSPHERIC WARMTH IS DUE TO THE LAPSE RATE/ADIABATIC COMPRESSION. No, the lapse rate describes how the temperature of a parcel of air changes from adiabatic compression/expansion of air as it sinks/rises. So, it can explain how the temperature changes during convective overturning, but not what the absolute temperature is. Explaining absolute air temperature is an energy budget question. You cannot write a physics-based equation to obtain the average temperature at any altitude without using the energy budget. If adiabatic compression explains temperature, why is the atmospheric temperature at 100 mb is nearly the same as the temperature at 1 mb, despite 100x as much atmospheric pressure? More about all this here.
7. WARMING CAUSES CO2 TO RISE, NOT THE OTHER WAY AROUND The rate of rise in atmospheric CO2 is currently 2 ppm/yr, a rate which is 100 times as fast as any time in the 300,000 year Vostok ice core record. And we know our consumption of fossil fuels is emitting CO2 200 times as fast! So, where is the 100x as fast rise in today’s temperature causing this CO2 rise? C’mon people, think. But not to worry…CO2 is the elixir of life…let’s embrace more of it!
8. THE IPCC MODELS ARE FOR A FLAT EARTH I have no explanation where this little tidbit of misinformation comes from. Climate models address a spherical, rotating, Earth with a day-night (diurnal) cycle in solar illumination and atmospheric Coriolis force (due to both Earth curvature and rotation). Yes, you can do a global average of energy flows and show them in a flat-earth cartoon, like the Kiehl-Trenberth energy budget diagram which is a useful learning tool, but I hope most thinking people can distinguish between a handful of global-average average numbers in a conceptual diagram, and a full-blown 3D global climate model.
9. THERE IS NO SUCH THING AS A GLOBAL AVERAGE TEMPERATURE Really?! Is there an average temperature of your bathtub full of water? Or of a room in your house? Now, we might argue over how to do the averaging (Spatial? Mass-weighted?), but you can compute an average, and you can monitor it over time, and see if it changes. The exercise is only futile if your sampling isn’t good enough to realistically monitor changes over time. Just because we don’t know the average surface temperature of the Earth to better than, say 1 deg. C, doesn’t mean we can’t monitor changes in the average over time. We have never known exactly how many people are in the U.S., but we have useful estimates of how the number has increased in the last 50-100 years. Why is “temperature” so important? Because the thermal IR emission in response to temperature is what stabilizes the climate system….the hotter things get, the more energy is lost to outer space.
10. THE EARTH ISN’T A BLACK BODY. Well, duh. No one said it was. In the broadband IR, though, it’s close to a blackbody, with an average emissivity of around 0.95. But whether a climate model uses 0.95 or 1.0 for surface emissivity isn’t going to change the conclusions we make about the sensitivity of the climate system to increasing carbon dioxide.
I’m sure I could come up with a longer list than this, but these were the main issues that came to mind.
So why am I trying to stir up a hornets nest (again)? Because when skeptics embrace “science” that is worse that the IPCC’s science, we hurt our credibility.
NOTE: Because of the large number of negative comments this post will generate, please excuse me if I don’t respond to every one. Or even very many of them. But if I see a new point being made I haven’t addressed before, I’ll be more likely to respond.
Let me take on your first one: “There is no greenhouse effect.” You should know that it is not the greenhouse effect itself that is at issue but the enhanced greenhouse effect, that part of it caused by the addition of a greenhouse gas to the atmosphere that causes global warming.. That is what IPCC actually means when they say greenhouse because early on they decided to drop the “enhanced” label as unhandy for explanations. It can be demonstrated that the enhanced greenhouse effect actually does not exist in several ways. Let’s start with Hansen’s 1988 presentation. He showed a rising temperature chart that started in 1880 and peaked in 1988. That high point in 1988, he said, was the warmest temperature within the last 100 hears. There was only a one percent chance that this could happen by accident. Hence, it followed that there was a 99 percent probability that it proved the existence of the greenhouse effect. Apparently no one checked his science and he has been getting away with this talk all these years. But if you take a look at his 100 year warming, courtesy of the Congressional Record, you find that his 100 year warming includes the early century warming from 1910 to 1940. For any warming to qualify as enhanced greenhouse warming, it is necessary that there must be a simultaneous increase of atmospheric carbon dioxide when it begins. This is necessary because the IR absorbency of a gas is proprtyof its molecules and cannot be changed. It is easay to find out what happened to atmpspheric carbon dioxide in 1910 from the extended Keeling curve. It was nothing. Hence, this warming can not be enhanceed greenhouse warming. Furthermore, if you have an enhanced greenhouse warming going, the only way to stop it is to remove the molecules absorbing IR from the air. That warming stopped in 1940 but nothing happened to atmospheric carbon dioxide, again. There is no doubt that the 1910 to 1940 warming is natural warming. We must remove it from his 100 year greenhouse warming which lops off 60 years from the end. What is left of his greenhouse warming now is a see-saw, 25 years of cooling followed by 23 years of warming. You don’t have to be a rocket scientist to understand that this in no way proves the existence of the greenhouse effect. But IPCC and company have been using the greenhouse effect in their models for 24 years and getting wrong predictions every time. You get that when you start venerating the emperor’s new clothes. Fact is that others have also fallen for this fake greenhouse effect and have been saying that they too think there is greenhouse warming, only not as much as the IPCC tells us. Get over it: there is no greenhouse warming. By that I do not mean that there is no greenhouse absorption of IR. There is but it does not cause warming for the very good reason that Arrhenius theory does not apply to the atmosphere. He measured absorption in the laboratory and found that carbon dioxide absorbed IR and got warm as a result. From that he jumped to the conclusion that adding carbon dioxide to the atmosphere would change the climate. His calculation showed that doubling the amount of CO2 in the air would raise global temperature by 4 to 5 degrees. Present day calculation is about 1.1 degrees Celsius. That is not very threatening so IPCC adds to it a positive water vapor feedback that can more than double it. But all this is in the absence of actual observations on the real atmosphere. The first person to measure IR absorption by the actual atmosphere was Ferenc Miskolczi. He used NOAA database of radiosonde observations going back to 1948 to determine atmospheric absorption of IR over time. And found that absorption was constant for 61 years while carbon dioxide amount increased by 21.6 percent over that same time period. That is sufficient to prove Arrhenius theory of greenhouse warming wrong. Miskolczi greenhouse theory (MGT) which he developed before he got to do measurements differs from Arrhenius in that it covers the more general case of several greenhouse gases simultaneously absorbing in the IR. When this happens, there exists an optimum common absorption window in the IR that the gases present jointly maintain. In the earth atmosphere, the greenhouse gases that count are carbon dioxide and water vapor. The optical thickness of their common absorption window in the IR is 1.87 which he calculated from radiation theory. If we now add some carbon dioxide to the atmosphere it will start to absorb exactly as the Arrhenius theory tells us. But this will increase the optical thickness and water vapor will start to diminish, rain out, and the optimum optical thickness is restored. This is what his observations of the NOAA database tell us. And this is what is happening today with the hiatys-pause that stole the warming from the IPCC. They are looking everywhere for that lost warming, even in the ocean bottom. But the answer is very simple from MGT: addition of carbon dioxide to the atmosphere is simply neutralized by condensation of water vapor and enhanced greenhouse warming they are searching for is not possible.
lb says:
May 1, 2014 at 2:17 pm
There is debate over the effect of mass alone on planetary T, but even considering just the GHE, one extra molecule of CO2 per 10,000 dry air molecules will have little effect, you’re right. And also that warmer is better than colder within the bounds of possible change in T.
That said, the atmosphere of Venus is not a good model for earth’s.
Engineer Ron says:
May 1, 2014 at 1:43 pm
You’re wrong, however on item #7. The ice core record is subject to huge smoothing error by virtue of temporal sampling limitations an enormous attenuation by virtue of CO2 diffusion between ice layers.
Ron there is very little diffusion of CO2 between ice layers. In the “warm” coastal cores that gives a broadening of the resolution from 20 years to 22 years at medium depth and from 20 to 40 years at full depth (70 kyears) in the Siple Dome ice core:
http://catalogue.nla.gov.au/Record/3773250
But there is no measurable migration in the “cold” inland ice cores like Vostok or Dome C. If there was the slightest migraiton, the quite fixed ratio between CO2 and temperature (proxy) would fade for each interglacial period 100 kyears back in time.
Even these low resolution ice cores (600 and 560 years resp.) would show the 100+ increase over the past 150 years…
And I have provided lots of comments on the reference you gave…
Thank you, Dr. Spencer. I see that the supportive comments far outnumber critical comments.
This was a useful exercise, I would enjoy seeing a list of the “top ten” skeptical arguments that are peer-reviewed and unassailable by the CAGW crowd. These could include the lack of warming in the past decade or so; relative insensitivity of climate to carbon dioxide levels; rising temperatures precede rising carbon dioxide levels & not vice-versa, etc.
Another “top ten” could be a list of the most ludicrous CAGW claims, such as Hansen’s “Venus Syndrome” scare-story: http://www.climatevictory.org/venus.html
As to #9 – a modest proposal… can you describe a method to measure your bath tub water temperature while filling it with warm water [both taps on] with precision and accuracy sufficient to honestly report its temperature to +/- 0.01 C in 1 minute intervals?
Let me save you some time, your bath tub water doesn’t have a temperature at that level of granularity and its dishonest to pretend it does, and we sure a hell didn’t measure the earth’s atmosphere to a similar granularity – ever – over any period of time. Therefore we don’t have a data pool sufficient to make statements about past states or make predictions about future states in the the realm of 2 significant digits. In fact the actual measurement set you could achieve in your bath tub in the conditions described and honestly report is probably well over 100x less accurate than 0.01 C. For the planet’s atmosphere it is obviously a lot more challenging a task carried out with a lot less care and control than you might exercise in your bath tub, and therefore the data pool is significantly less accurate and less precise than available in that thought experiment.
With that fact in mind when we look at the pool of alarmist global warming models and the claimed granularity of Global Average Temperature [GAT] information from the past and the predictions made going forward, its pretty obvious the exercise is well outside of what was measured and therefore well outside what anyone could rationally claim to be able to predict. And lo and behold – such predictions in fact don’t “hold water”.
Pretending we know that the GAT in 1939 was 0.36 C less than it was in 1998 is pretending. For all we know it was actually hotter in ’39, because the simple truth is we didn’t measure accurately or precisely enough to honestly report a difference that small.
#7 is still a mystery to me (both the argument and what is wrong with it). Maybe a link?
If #9 was as claimed, it should be a T**4 average.
I’m surprised that an average temperature of your home is claimed to make sense, when the refrigerator and gas cooktops are included.
Latitude says:
May 1, 2014 at 2:06 pm
was talking biology Ferd………..
For the whole biosphere, we know the balance within large margins of error, thanks to the oxygen balance:
http://www.bowdoin.edu/~mbattle/papers_posters_and_talks/BenderGBC2005.pdf
That gives some 1 GtC/year net uptake by the whole biosphere. The earth is greening… But not enough to gobble up all of our 9 GtC/year emissions…
I know it is your blog, but I am saddened you snipped my comment identifying Pierre Latour’s response to Spencer. It is not a food fight but a series of legitimate scientific points and questions in a very important debate. My experience continues to be that the more specialists are made aware of the use of their area for climate science, especially IPCC style, the more problems of misuse arise some through ignorance and some deliberate.
LT:
I write to answer your question and not to deflect the thread.
At May 1, 2014 at 1:34 pm you write
As you say, the rise in atmospheric CO2 concentration does not match the anthropogenic emission. And this is not supportive of the assumption of “accumulation” of some of the anthropogenic CO2 causing the rise. Indeed, the dynamics of the seasonal rise clearly refute that the rise is caused by saturation of the system inducing accumulation of part of the anthropogenic emission.
Also, the rise in atmospheric CO2 concentration does not match the temperature rise. This is clearly seen during this century when there has been no discernible (at 95% confidence) rise in global temperature but the rise in atmospheric CO2 concentration has continued unabated.
But these facts do NOT indicate that either the anthropogenic emission or global temperature change is not the cause of the rise in in atmospheric CO2 concentration.
Some effects of the carbon cycle have rate constants of years and decades so the system takes decades to adjust to an altered equilibrium. Indeed, the ice core data indicates a lag of atmospheric CO2 behind global temperature which suggests that achieving the equilibrium can take ~8 centuries.
The existing observations are all consistent with the carbon cycle adjusting to a changed equilibrium to provide the recent rise in atmospheric CO2 concentration.
And if the equilibrium state of the carbon cycle has changed then the cause of the rise in atmospheric CO2 is whatever caused the alteration to the equilibrium state. Perhaps the anthropogenic emission has altered the equilibrium state. And perhaps the temperature rise from the Little Ice Age (LIA) has altered the equilibrium state. And perhaps … etc..
So, I do not know what has caused the recent rise in in atmospheric CO2. In reality nobody knows the cause because the available data does not indicate the cause, but some people think they know the cause.
I hope this brief answer is sufficient for you and does not deflect the thread.
Richard
Just look at this year’s (and other years) temp records for the Arctic (80+ degs North) … see anything unusual? http://ocean.dmi.dk/arctic/meant80n.uk.php
Jimbo: Indeed, he probably got it wrong, as most of the global warming measured is a side effect of the much underestimated UHI; due to rapid urbanisation since the 50’s (the earth’s population grew from 1 billion to over 7 billions in half a century, and the climate stations didn’t move during that time). There are some human manipulations of the data that seem to come into play eventually. Those 2 factors are still human causes for the warming as seen by the data series released to the public though… While CO2 is a greenhouse gas, to some extent (the molecule has a polarity, like H2O, so electromagnetic interactions at the molecular level are at play too); it is probably not the main contribution to the warming that the earth has seen since a century. But at least tonight i’ve understood that the weight of the molecule of CO2 probably doesn’t matter for the ideal gas approximation, as much as possible electromagnetic interactions.
About #7: IMHO Dr Spencer’s explanation is correct in essence if not detail, and the arguments here suggest it could have been expressed better. Perhaps the pertinent question is by how much would atmospheric CO2 concentrations have risen if there had been no man-made CO2?
Ferdinand Engelbeen (May 1 9:39am) provides the answer: max 8ppmv. Rather more than Dr Spencer suggests, but even allowing for lots of error it’s a small amount nonetheless.
Dr Spencer : Many thanks for the sanity that you have promoted over the years. Please can you refine your 10 points in light of the comments here, and post them in a permanent place for ongoing reference. And of course referenced from, or copied in, WUWT, JoNova, etc.
If Co2 were a layer in the atmosphere how thick would it be?.
.“THERE IS NO GREENHOUSE EFFECT”
There is a difference between a “total effect” (e.g. from some zero level), and an “incremental effect” (e.g. from some non-zero reference level). Beer’s Law is relevant here, as I often see worrymongers quoting the ~30K rise in temperature as if this is supposed to be relevant to the assumed enhanced GHE.
Some form of saturating effect in the atmospheric system is all it takes to blow the enhanced GHE argument. We know the climate seems to operate within limits. The “hotspot” is nowhere to be seen. The models (with non-saturated assumptions) are poor predictors. There is plenty of evidence to point to saturating processes, even if we have not presently identified and described them.
If you change to: “there is no ENHANCED greenhouse effect”, you get a fair sceptical question.
“THE GREENHOUSE EFFECT VIOLATES THE 2ND LAW OF THERMODYNAMICS”
The crux is whether climate sensitivity is amplified by positive feedback. Can a rise of temperature CAUSE further rise in temperature? Energy added to the system caused by the last rise in energy in the system. It is essential to demonstrate conservation of energy and the physics for accumulation in the atmosphere to run this argument.
And it can be useful to test the same argument is the reverse direction as the same physical processes should still be active. Positive feedback suggests a drop in temperature would cause further drop. Why should we not be in a panic over imminent collapse of temperatures?
If you change to: “POSITIVE FEEDBACK in climate sensitivity violates the 2nd Law of Thermodynamics”, you get a fair sceptical question.
“THE IPCC MODELS ARE FOR A FLAT EARTH”
Maybe not in general, but the arguments about positive ice albedo feedback come pretty darned close.
Although complicated by seasonal variation, positive ice albedo feedback falls into a trap of assuming each increment of ice retreat will add energy (i.e. the exposed surface will cause net absorption).
This overlooks cos-theta for incoming solar – the next increment of ice retreat must therefore have a lower energy increment compared to the last. But the exposed surface then radiated into the hemisphere above – this is not a function of cos-theta of the incoming solar. It suggests some equilibrium state to be reached (all other things equal).
So it is no coincidence that there is ice at the poles, and it expands in the polar winters.
And like before, the idea can be tested by considering movement in the opposite direction. For an advancing ice sheet, each increment of ice advance would cover a better absorber. In this case, cos-theta would be increasing as the ice advances and therefore the next increment in albedo effect would reject an increasing quantity of incoming solar. It suggests albedo feedback (if it existed) would be more potent in the advancing mode as cos-theta increases. (Panic!)
If you change to: “POSITIVE ICE ALBEDO FEEDBACK is for a flat Earth”, you get a fair sceptical question.
JBJ: Just look at this year’s (and other years) sea ice extent for the Antarctic… see anything unusual? 😉 This is weather, not climate. What’s interesting about the polar regions is that the duration of day and night has some interesting side effects on the climate of these regions. During the polar night they’re merely heat sinks, and the temperature in antarctic falls so low that CO2 may become liquid and eventually solid. Can’t remenber of any studies that quantifies the quantity of dry ice formed during the polar winters, strangely.
A few comments say that O2 & N2 dont absorb EM. Hasn’t it been established that, not only ‘they do’, but also that they are actually quite significant in the big picture?
markrust: Co2 is not a layer in the atmosphere, but the concentration of heavier gas decreases more rapidly as a function of altitude.
I didn’t know it was the cold temperature of my clothese that kept me warm!
“””””…..Jimbo says:
May 1, 2014 at 12:46 pm
9. THERE IS NO SUCH THING AS A GLOBAL AVERAGE TEMPERATURE …..”””””
Well the earth itself does not do averages; so whenever you read that word, you know it is a number that somebody calculated. Nobody ever observed an average temperature; or an average anything else either.
But the concept of average is quite precisely defined, in statistical mathematics.
But as Dr Roy said; you don’t need to know the average Temperature; you just need to know how the result of your calculation for some specific data set that is updated periodically, changes with those updates; presuming that you retain the same algorithm for all calculations.
Trouble is that we have people constantly changing the values calculated years ago, and trying to assert that they are using the same algorithm.
I don’t get the #6 issue, which is not to say it’s not an issue.
When moisture evaporates and then rise in the atmosphere, it presumably is storing gravitational potential energy. So when the rain drops come crashing down, do we get that PE back as KE, and “heat” when the rain drops collide with the ground ?? Never have thought much about the adiabatic thing.
One thing that seems self evident to me concerns delay effects.
We all see how at sunrise, the lower atmosphere and surface tend to immediately start heating, and after sundown, they will also be cooling.
So the Instantaneous Temperature anywhere in the atmosphere/ weather system, responds essentially instantaneously to what is happening in terms of incoming solar energy, and cloud blocking, Raleigh scattering, et cetera.
So if the CO 2 changes; and it does quite slowly; 2 ppm / yr., or 6-18 ppm in 5 months for the fine print; the effect of that on atmospheric warming, is not going to take any 800 years to manifest itself; it will happen immediately, just as a cloud passing in front of the sun, will cool the shadow zone instantly.
So I’m not into any cross correlations versus delay offset stuff. The effect on temperature of GHGs is rather immediate.
Now the 800 year or so offsets in the ice core records, between CO2 proxies, and temperature proxies. which seems quite evident in the reported data; I just don’t get a mechanism for.
And the band saturation thing is obvious. Beer’s law relates to the absorption of “specific wavelengths” versus optical path or absorbing species abundance. It does NOT apply to the “energy transmission” because it presumes that the captured photons stay dead; they do not stay dead. Einstein in his 1909 papers mentioned the “fluorescence” of the absorbing material, and Stokes had already observed, and alerted Einstein, to the fact that the fluorescence was always at a longer wavelength, lower energy photon emission. The “Stokes shift” is now a standard buzzword of solid state lighting. (white LEDs).
In a fluorescent lamp, a UV emission in the tube containing mercury, produces no visible light; but the UV photons cause fluorescence in the phosphors coating the tube., and the Stokes shift photon energy loss, going from UV, perhaps 4-5 eV photons to 2.5 eV or so visible photons, is the energy loss that appears as “heat” at the tube envelope. The loss in the phosphor, is what makes fluorescent tubes warm.
White LEDs typically use a 460 nm blue LED, perhaps 3.0 eV photon energy, to excite the 2.5 eV phosphor, but the surviving blue photons combined with the broad yellow photons from the phosphor, provide the white light; but the blue component involves no Stokes shift loss, which is why they are more efficient light sources.
So IR photons, also don’t stay dead in the CO2, but get a new life to move on, where they will no doubt, encounter another CO2, or whatever GHG molecule, to catch them.
So all that changes, is how thick (or thin) an air layer it takes to get them all. So yes the opaque already thing is a red herring.
I’m not a fan of the Trenberth “earth energy budget”, and also call his diagram, a “cartoon”. But not in any derogatory sense. My objection to it is that the numbers are actually power density numbers; not energy numbers, and the magnitude of those numbers, is quite different from the real observed rates of energy flow, so it is not a valid depiction of what really happens TSI(0) is still 1366 W/m^2, and not 342., and different things happen for those two numbers as a result.
But anyway, I personally believe Dr Roy has already turned over the Rosetta stone of climate stability. Its the strong negative cloud feedback, that frustrates everything else that is trying to change the thermostat. And Frank Wentz et al (RSS) got the experimental data to prove the mechanism.
lou, no, isolation, such as cloth, is a means of suppressing the velocity of air, which means your body can more easily heat a limited quantity of air efficiently.
“Despite the fact that downwelling IR from the sky can be measured”
co2 at differing heights.
If co2 radiates energy downwards can co2 below absorb this energy. If so and this co2 then re- emits downwards and upwards , can the co2 above absorb this energy to re- emit it to the co2 below again?
Very bizarre situation.
I had read somewhere that if the amount of CO2 in the atmosphere increased the temps wouldn’t, because the amount of CO2 that is already in the atmosphere has already reached it max heat trapping potential. Is that correct? (apologies for the unscientific terminology).
What has caused the temperature to remain flat for a couple of decades despite the increased CO2 in the atmospehere? Are you saying that the “man-made” CO2 must cause global warming in the long term, but that some short term factors are holding the temperatue down for now? What are those factors? When will they change and when they do change, how much do you expect the global average temperature to rise by?
You are indeed confused about pressure broadening, different gases have different broadening coefficients, in particular the ‘self broadening’, in this case of CO2 by CO2. Check out references on line by line calculations such as HITRAN, Spectracalc covers it I think:
independent of location in a well-mixed atmosphere. The probability of any given collision being CO_2 on CO_2 is then 
— one collision in 10 million is CO_2 on CO_2. Even if we track individual CO_2 molecules, the probability of the next collision of a CO_2 molecule being CO_2 on CO_2 is 
. That means that one expects the fractional contribution of the total line broadening due to CO_2 on CO_2 to be 0.03%. Even if it produced twice the broadening “per collision”, nobody would care — you couldn’t resolve it from the total with any measurement we are capable of. And note that this is really pretty unlikely — most of the broadening comes from phase interruption, not from resonant energy exchange AFAIK or can estimate.
of order of 0.01%. That is the very definition of negligible.
Pascals, with an enormously larger MFT between collisions, would you expect any sort of significant Lorentzian line width? Of course not — as the document you linked indicates (as well as Petty’s book which is sitting next to me as I write this) — this is precisely the region that inhomogeneous broadening due to thermal doppler shift dominates. The Lorentzian line width is completely negligible. So why does adding a lot more collisions with nitrogen somehow effect the Lorentzian contribution from CO_2 on CO_2 at this partial pressure?
http://www.spectralcalc.com/info/CalculatingSpectra.pdf
Actually, no it doesn’t. It asserts that same species collisions have a different effect on broadening than collisions between species — no argument there as long as those effects are order unity — and then uses the same formula with no partial pressure indicated to estimate the total broadening, which makes no sense to me at all. The actual cause of pressure/collisional broadening is reviewed in Van Vleck and Weisskopf, Reviews of Modern Physics 17, p 227 (1945). Not so “Modern” any more, but more than adequate. This paper makes it clear that the basic cause of collision broadening is the phase interruption of an otherwise pure frequency train at intervals of the mean free time between collisions. The fourier transform of a pure harmonic signal phase interrupted with delta-correlated noise is Lorentian — end of story. The paper does all for a small effect due to either the details of the quantum interaction in a collision or a medium with inhomogeneous mean times between collisions, but the latter is extremely rare and again, the effects are order unity against the only really important parameter, the mean free time between phase interrupting collisions of any sort.
Now let’s do an interesting estimate. Suppose we are back in 1950, at 300 ppm CO_2. At that point the probability of a molecule being CO_2 is around
If one doubles the concentration to 0.06%, nobody still cares. Even if the per-collision broadening of CO_2’s lines were ten times as strong for CO_2 on CO_2 as the per-collision broadening of CO_2 on N_2 or O_2, there just aren’t enough of the latter compared to the number of the former for it to constitute one whole percent of the total absorptivity, and the total absorptivity doesn’t have anything like a linear effect on the total GHE. We’re looking at a log effect based on an increase in
Note well — we’re not talking about increasing CO_2 concentration so that the CO_2 on CO_2 collisions go from 10% of the total CO_2 on anything total to 50% of the total CO_2 on anything total. That would produce a meaningful variation of the total atmospheric absorptivity in the CO_2 band even if the lorentian linewidth of the former doubled compared that of the latter for non-CO_2 collisions for the same mean free time between collisions (holding pressure and mean density approximately constant, in other words). But I simply don’t see any way that even a fairly hefty increase in line width due to CO_2 on CO_2 collisions could ever make their contribution to the total line width anything but negligible for any order unity variations of CO_2 concentration in the absolute range from 0 to 1000 ppm.
Look at it this way. If you had a very dilute gas of pure CO_2 — one at the partial pressure of CO_2 in the atmosphere, that is,
I don’t think that it does. I’ve had a hard time following this argument since I started looking at Beers-Lambert. It looks like a simple error — collision broadening is dominated by the mean free time ONLY, and only fractionally altered by per-species variations, and you cannot use the mean free time of collisions between CO_2 and either N_2 or O_2 in an estimate of the broadening due to CO_2 on CO_2. You have to use the mean free time between CO_2 on CO_2 collisions, which is many orders of magnitude larger so even if the lines broaden more, they have to broaden orders of magnitude more for it to matter. And they don’t — the basic broadening mechanism is almost exactly the same.
If anybody has measurements of absorptivity variation in O2-N2-Ar mixtures with 0.03% CO_2 in the CO_2 bands, I’m happy to be convinced otherwise, or else feel free to direct me to physics that suggest that the actual total pressure P should in any way be relevant to the MFT between same-species collisions in a mixture rather than the partial pressure. I can easily believe that total pressure is related to the MFT, and that Lorentzian linewidth is dominated by MFT alone, but I’d be very skeptical of any argument that CO_2 the any-species MFT matters much in the per-species Lorentzian as a fraction of the whole.
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