The Logarithmic Effect of Carbon Dioxide

Guest post by David Archibald

The greenhouse gasses keep the Earth 30° C warmer than it would otherwise be without them in the atmosphere, so instead of the average surface temperature being -15° C, it is 15° C. Carbon dioxide contributes 10% of the effect so that is 3° C. The pre-industrial level of carbon dioxide in the atmosphere was 280 ppm. So roughly, if the heating effect was a linear relationship, each 100 ppm contributes 1° C. With the atmospheric concentration rising by 2 ppm annually, it would go up by 100 ppm every 50 years and we would all fry as per the IPCC predictions.

But the relationship isn’t linear, it is logarithmic. In 2006, Willis Eschenbach posted this graph on Climate Audit showing the logarithmic heating effect of carbon dioxide relative to atmospheric concentration:

And this graphic of his shows carbon dioxide’s contribution to the whole greenhouse effect:

I recast Willis’ first graph as a bar chart to make the concept easier to understand to the layman:

Lo and behold, the first 20 ppm accounts for over half of the heating effect to the pre-industrial level of 280 ppm, by which time carbon dioxide is tuckered out as a greenhouse gas. One thing to bear in mind is that the atmospheric concentration of CO2 got down to 180 ppm during the glacial periods of the ice age the Earth is currently in (the Holocene is an interglacial in the ice age that started three million years ago).

Plant growth shuts down at 150 ppm, so the Earth was within 30 ppm of disaster. Terrestrial life came close to being wiped out by a lack of CO2 in the atmosphere. If plants were doing climate science instead of us humans, they would have a different opinion about what is a dangerous carbon dioxide level.

Some of the IPCC climate models predict that temperature will rise up to 6° C as a consequence of the doubling of the pre-industrial level of 280 ppm. So let’s add that to the graph above and see what it looks like:

The IPCC models water vapour-driven positive feedback as starting from the pre-industrial level. Somehow the carbon dioxide below the pre-industrial level does not cause this water vapour-driven positive feedback. If their water vapour feedback is a linear relationship with carbon dioxide, then we should have seen over 2° C of warming by now. We are told that the Earth warmed by 0.7° C over the 20th Century. Where I live – Perth, Western Australia – missed out on a lot of that warming.

Nothing happened up to the Great Pacific Climate Shift of 1976, which gave us a 0.4° warming, and it has been flat for the last four decades.

Let’s see what the IPCC model warming looks like when it is plotted as a cumulative bar graph:

The natural heating effect of carbon dioxide is the blue bars and the IPCC projected anthropogenic effect is the red bars. Each 20 ppm increment above 280 ppm provides about 0.03° C of naturally occurring warming and 0.43° C of anthropogenic warming. That is a multiplier effect of over thirteen times. This is the leap of faith required to believe in global warming.

The whole AGW belief system is based upon positive water vapour feedback starting from the pre-industrial level of 280 ppm and not before. To paraphrase George Orwell, anthropogenic carbon dioxide molecules are more equal than the naturally occurring ones. Much, much more equal.

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This seems a perfectly clear exposition of what’s wrong with AGW theory.
So what in the above it beyond the capabilities of main-stream journalists? If I was a Harabin or Black, I would want to know from the Met Office experts exactly where the errors are in this, because clearly there MUST be some serious mistake, as we know from the Met Office just last week that AGW is real, and MUST be due to man-made interference with nature.
So seriously, if any main-stream journalists get to read this, why are you not doing your jobs and investigating? Surely it is the low-level arguments such as this that need to disproved by the AGW supporters who constantly tell us that the science has been clear for 150 years.
If they cannot disprove this, why do the MSM listen to them?

Richard Telford

I don’t know if this post was supposed to be misleading and confusing but is certainly is.
Forcing is logarithmic! Surprisingly, climate scientists were aware of that.
The final graph is complete junk. Comparing forcing due to CO2 alone with forcing due to CO2 + feedbacks and finding that the latter is larger is pretty trivial.


Excellent post for the layman. But it would be nice to have a few citations. What is the source of the claim that “the first 20 ppm accounts for over half of the heating effect ?”
But the following is the true statement that is gives some perspective (and puts a smile on my face): If plants were doing climate science instead of us humans, they would have a different opinion about what is a dangerous carbon dioxide level.

Lawrie Ayres

The IPCC projection looks decidedly odd even for a layman. Unbelievable in fact. Since the amount of warming is also in doubt due to poorly sited and deleted thermometers I’m beginning to wonder what the AGW hypothesis has left to support it. Manic rants from those about to lose their cash cow appears to be the last resort. Even chairman Rudd has gone quiet and Penny Wrong has gone off to buy some floodwater.


“To paraphrase George Orwell, anthropogenic carbon dioxide molecules are more equal than the naturally occurring ones. Much, much more equal.”
Borrowing another idea from Orwell’s “Animal Farm”:
– Four legged CO2 is a friend.
– Two legged CO2 is an enemy.


They have a nice theory, they have models that use the theory but these models future predictions all end up being wrong so end of theory in my mind.


The temperature sensitivity of CO2 is clearly not logarithmic over the entire range. The logarithmic relationship appears to range from about 40ppm to about 200ppm. After that it looks more like a 1/x type relationship. Maybe the whole curve is closer to 1/x. Has anyone tried doing such a plot?


I’ve read Davids papers on this before (I’m a layman I hasten to say). Apart from a derivative graph on the Junk Science site and a quote from Fred Hoyle I’ve not been able to dig out any further papers that support this idea. I’m told the science is settled, but something as basic as this seems to cut right to the heart of the whole argument…how could something as simple as this have been overlooked?


forcing due to CO2 + feedbacks
You mean like the melting ice-caps decreasing albedo. How’s that particular forcing working out for you?
The idea that water vapour suddenly kicks in at a particular CO2 concentration is extremely odd. Water vapour levels doesn’t depend on CO2 levels, just temperature and wind. We already have parts of the world which remain at high temperatures year round — the tropics. They would already be exhibiting the vapour feedback, and have done so for centuries. We have parts of the world which are always cold — the poles. No substantial mechanism effect there because they don’t get hot enough. So any water vapour effects will have to come at the margins, and they won’t generate the accelerating effect you need.
The idea that water vapour will cause accelerated warming seems to rest on the idea that the earth is a consistent temperature. Since it isn’t, there can be no magic kick-in point.
So what forcing are you actually relying on?


Nice one David,
I can’t stand it when an alarmist states (unchallenged) that the sceptics have not come up with one argument to upset the settled science. Well how about we get this into the head of the next talking head (to challenge) – hey dude CO2’s contribution is logartithmic not linear – heck that scientific enuff for ya. Plimer touches on it in his book – but well explained here, good job. I like the line about the point of view of the plants. You know, I reckon corals and foraminifera might like it for their skeletons too.

Mr Archibald:
May I translate this article into Spanish and publish it in my blog, with due recognition and links to the original, of course?


David Archibald’s conclusions are either true or not. Or am I being simple-minded? If he’s wrong why don’t climate scientists stop holding their noses and say why. Wouldn’t that be science?
This we’re-not-talking-to-each-other mentality is what is so frustrating to non-scientists like me.
I’d like Richard Telford to comment in greater detail. Then I’d like to see David Archibald respond.
And yes, I know we’ve all got day jobs … but hang on! Aren’t we sceptics all funded by Big Oil?


Richard Telford (01:00:29) :
May I respectfully suggest that you re-read the penultimate para. of the post, think, engage brain, think again, then make a considered response.

P Gosselin

I’ve read in literature somewhere that CO2 contributes to about 25% of the greenhouse effect, i.e. 7-8°C. Can you cite where the 10% value comes from?
And there are other logarithmic curves, e.g. Lindzen, that are less flat after the first 300 ppm than the ones presented above. I’m wondering which are correct. Has Willis’s graphs been peer-reviewed? (Not that it makes a difference).

Peter Taylor

Its a curious thing that this point – well made by David here, still gets re-iterated and as far as I am aware, without response from the modellers. In the middle of last year I wrote a book aimed at my fellow environmentalists where I outline this issue – especially the 300% ‘gain factor’ in the equations – which is not so easy to derive from IPCC documents and for which I must thank Christopher Monckton in his article for the American Physical Society, where he tracks it down to James Hansen way back at the very beginning. It is a theoretical feedback, as Richard Lindzen pointed out at IPCC-1 in 1990! The modellers have taken the ‘warming’ (partly it now appears to have conjured and manipulated in the ‘gridded data set’ process) as evidence of the theoretical projection – and small wonder that when, after 2002, the warming ceased (no appreciable rise in upper oceanic heat content which is where 80% of the ‘warmth’ is held) that Kevin Trenberth at NCAR states in exasperation that it is a ‘travesty’ that they can’t account for the ‘lack of warming’.
You would think that at least one environmentalist from the long list of IPCC supporters would have either written to me, or pointed out in numerous public talks and discussions, where the refutation can be found – or that the MetOffice would have issues some guidance. Not one word!
So – given that this blogsite is visited by the orthodox – he is a challenge – please explain in simple terms, what is wrong with David Archibald’s presentation. I, for one, am open to listening and being re-educated – I care about the future of humanity, biodiversity…..the planet, but right now much of what I and others greatly value is threatened not by the projected consequences of carbon dioxide, but by the supposed remedy for climate change which will seriously and immediately damage landscape, biodiversity and community throughout the world, not to mention draining the pockets of taxpayers in a feeding frenzy of ‘jobs-for-the boys’ (Friends of Rajendra Pachauri rather than Friends of the Earth) – the technologies of turbines, barrages and biofuels.
So lets have an intelligent dialogue around this central issue – please!


Richard Telford (01:00:29) :
“I don’t know if this post was supposed to be misleading and confusing but is certainly is. Forcing is logarithmic! Surprisingly, climate scientists were aware of that.
The final graph is complete junk. Comparing forcing due to CO2 alone with forcing due to CO2 + feedbacks and finding that the latter is larger is pretty trivial.”
Looks like you have an excellent opportunity to demolish the sceptics with at most one follow-up submission which I hope you’ll make. Please avoid abuse such as ‘complete junk’ (makes you feel better but does not enlighten us) and tell us exactly where the author has gone wrong and mislead us

Mari Warcwm

Richard Telford
Why is the last paragraph complete junk? Forcing is logarithmic. Surprisingly, climate scientists were aware of that….. were they? So why do you get such alarming amounts of warming out of a trace gas?
Either you know a lot that needs to be explained to the rest of us, or you don’t now nuffin.

Richard Telford (01:00:29) :
I don’t know if this post was supposed to be misleading and confusing but is certainly is.
Forcing is logarithmic! Surprisingly, climate scientists were aware of that.

Then why do their models produce an algebraic result?
Reply: Do you mean arithmetic? ~ ctm

David Wells

If these graphs display the reality then why does the IPCC and the MET office want – seriously want – to continue propating the myth of AGW what is the purpose? If someone could describe to me in simple detail the reason behind the corruption of data and evidence that at the end becomes simple propaganda then whilst not being happy with the current situation I could at least understand why it exists.
You see it is a really big issue because if the BBC is correct according to their documentary serious about the solar system (last night) we only have 5 billion years left to sort the problem out.
Within that time frame the sun will implode and turn planet Earth into Walkers crisps hopefully if Al Gore is still around then he will get fried first so I am not going down to the gym and then restrict my diet to the minimum amount of calories so I live long enough to watch the episode on reality TV, I cant wait!
David Wells


I’m a little confused on this. The logarithmic nature of the Beer-Lambert law is well established but my understanding is that it applies even with an abundance of IR radiation that CO2 can absorb and dissipate as kinetic energy. Now, I’m under the impression that there exists a scarcity of IR radiation in the wavelengths which CO2 absorbs and the only effect of increasing the amount of CO2 in the atmosphere is that this finite amount of available energy gets absorbed closer to the ground.
So, is it correct that there are, in fact, two influences here, i.e. (a) the logarithmic impact on temperature according to the Beer-Lambert law and (b) the finite amount of reflected IR energy already being absorbed to extinction by the CO2 already in the atmosphere. Can someone please clarify this for me?

Mike J

MC – thanks for the link : brilliant debating, just superb. Monckton, with wit and humour aplenty, describes the reduced greenhouse effect of each additional atmospheric CO2 molecule over its predecessor, so this debate is not entirely off topic. It is well worth a watch if you have a spare 80 minutes or so.

If their water vapour feedback is a linear relationship with carbon dioxide, then we should have seen over 2° C of warming by now. We are told that the Earth warmed by 0.7° C over the 20th Century.

I’m not sure what claim the first sentence is based on. Can the writer elaborate?
My initial thoughts when I look at the post. The current radiative forcing at top of atmosphere from 380ppm of CO2 is around 1.7W/m^2 and from all increases in “greenhouse” gases = 2.4W/m^2. What I would call “non-controversial physics”, because it nicely ignores the rest of climate effects – the radiative-convective effect in isolation.
When you calculate the “rule of thumb” surface temperature increase from these 2 numbers above from the Stefan-Boltzmann equation you get 0.5’C and 0.7’C increase in surface temperature respectively. This is without feedbacks. You can see this all laid out in CO2 – An Insignificant Trace Gas? Part Seven – The Boring Numbers
But these are just rules of thumb – a “ready reckoner” approach to save standing in the long queue for the GCM each time you want to know something..
As far as I understand the point of this post, the climate modeling community is wrong because the current temperature increase isn’t 0.5’C x 2 or 0.7’C x 2 ?
I have my skepticisms about the climate models, but is this critique based on what climate modelers say? Is there a paper to reference?
The water vapor feedback is perhaps one critical aspect of climate models.
Do climate modelers presume it linear from pre-industrial times?
Do they calculate it to be linear from pre-industrial times?
I don’t know the answer. There seems a presumption in the article but no reference. It would be nice to check.
A few extra notes on the boring detail..
2. Where did “Carbon dioxide contributes 10% of the effect” come from? Kiehl and Trenberth (1997) calculate CO2 as about 26% of the “greenhouse” effect (see CO2- An Insignificant Trace Gas? – Part Five
3. Where does the forcing calculation in the 2nd graph come from and what is it saying?
The IPCC, effectively quoting Myhre (1998), says radiative forcing at top of atmosphere = 5.35x ln(C/Co), where Co is industrial levels of CO2, 278ppm. It is specified in boring detail (see it at the reference above) and tells us the expected addition to radiative surface forcing.
This 2nd graph says “Net downwards forcing” – at surface? at TOA? And is this after feedback, before feedback?


Please can we all play nicely!
Contrast the comment by Antonia (02:14:59), which attempts to get more information from Richard Telford, with the following one from Ronaldo (02:17:36) which is guaranteed to kill any serious discussion.
What’s the point of the nastiness? It doesn’t help anyone.

“The whole AGW belief system is based upon positive water vapour feedback starting from the pre-industrial level of 280 ppm and not before.”
This is just assertion. No reference, no cite. It’s a fabrication.

Positive feedback, assumed by the AGW hypothesis, can’t just kick in today or at 280ppm: it would have to apply at all CO2 concentrations if such feedback exists. If every 20ppm CO2 causes 0.46 degC warming, then this would hold for concentrations below the level of today, and because of the logarithmic effect, each 20ppm reduction in CO2 concentration would give a monotonically increasing effect on cooling (lack of heating). So going down to the so-called pre-industrial level of 280ppm would appear to knock out about 2.5 degC of heating, if this positive feedback be true.
The fourth graph says it all, if your calculations are correct: the cumulative effect declines to zero at around 280ppm. No – that can’t be right: any cumulative effect must go through the origin: there can be no good reason why positive feedback would kick in at 280ppm. I would expect to see the cumulative effect starting at the X-Y axes origin and monotonically increasing with CO2 concentration, BUT with the increase in the cumulative temperature per 20ppm CO2 decreasing with increasing CO2 concentration.

Bill Tuttle (02:43:21) :
Then why do their models produce an algebraic result?
Reply: Do you mean arithmetic? ~ ctm

Yup — thanks, Charles.
Too little sleep from enjoying the celebratory tracer fire over here last night…


There does appear to be some question as to the actual, say 1880, level of atmospheric CO2. At the Air vent blog points out that perhaps that generally accepted figure of 280ppm, may be too low a figure. If we are questioning assumptions, then this seems to be one that needs rechecking.

Dave Wendt

Where do the numbers in the second graph, indicating CO2 contributing over 250W/m2 to the downward forcing, come from. These two papers
which describe experiments which used spectral analysis of downward longwave radiation to determine the contribution of the various GHGs to the total signal, show that CO2 doesn’t contribute more than 35W/m2 at its most active range and would likely be below 10W/m2 throughout most of the Tropics and Subtropics.


A great post by David; of course the effect of increasing CO2 on temperature has been known to be miniscule by the IPCC because that is why they have invented the enhanced Greenhouse effect which depends on the slight warming from increased CO2 releasing water into the atmosphere with its much greater greenhouse effect.
This is wrong on many levels despite Mr Telford’s typical warmist snark. First there has not been increased levels of water going into the atmosphere; Paltridge’s excellent paper establishes that with the ghost in the machine of Miskolczi present in the stability of optical depth over the enhanced greenhouse period.
Secondly, the role of clouds has been profoundly misunderstood by AGW proponents; the recent Pinker et al dispute between Monckton and Lambert in their Sydney debate shows this; the SW flux findings of Pinker, most likely caused by cloud variation, are sufficient to explain recent warming. In this respect Monckton, despite misunderstanding cloud forcing, was correct about climate sensitivity to increases of CO2; this tiny CS from ^CO2 must be based on the log effect described by Archibald and this fact coupled with the moderating role water plays against temperature movement in any direction fundamentally contradicts AGW.

Dave N

sHx (01:06:52) :
Refer the MODTRANS facility, University Of Chicago.
Alarmists will tell you that the climate is far more sensitive than Archibad suggests, however I’ve never seen a convincing argument for *why*

David Archibald

Heber Rizzo (02:05:53) :
Please do. If you email me at david.archibald @ ,
I can send you the original.


“Plant growth shuts down at 150 ppm”
Try telling that to Mr 350.


Great News: Over the past 140 years the British weather observatory situated in the Himalayas revealed a temperature drop of .4 degrees
Senior scientists at the Wadia Institute of Himalayan Geology (WITG) has rejected the Global Warming Theory and told that the Himalayas are quite safer zone on earth, where Global Warming has no role in controlling the conditions. They also said that the conditions of Himalayas are controlled by the winter snowfall rather than external factors like much hyped Global Warming.


So a doubling of CO2 relative to pre-industrial times leads to an increase of 2W/m2. The difference between the solar minima and solar maxima IIRC is about that much.

Just in case you missed it, more over enthusiasm from the IPCC on CO2.

David Wells

God save me from scientists and pseudo scientists, you are all as bad, if you are so concerned about the environment then for goodness sake do something practical eg dont buy biscuits or anything else that uses palm oil.
50,000 Orang Utans have already been sacrificed for your own personal health and wellbeing before you even consider the average Americans concern about the cash in his pocket, palm oil being the cheapest vegetable oil available, then if you moan about water shortage then consider that it takes 14000 litres of fresh water to make one litre of biofuel.
Who for goodness sake cares whether or not Co2 is logarithmic or suffers from attention deficit disorder and maybe subject to rabies, what we do know is that none one single prediction made by the IPCC, Gore or Hansen has come true therefore commonsense would clearly indicate that its all hot air and that only someone severely retarded would want to continue this idiotic debate rather than actually do someone about the absolute destruction of our environment.
Americans should eat less hamburgers not because cows belch but because more rainforest is destroyed each year just to fuel the average Americans desire to cheap subsidised food.
Get your face out of the screen, go out and let some daylight into your challenged brains and recognise that none of you bellacheing about pointless statistics well change anything or is your chosen sense of status more important that the biodiversity that you think will be saved by your craven indulgence?
Get a life, you only have one so make use of it.
David Wells

John Finn

I would urge WUWT readers to take anything written by David Archibald with a large pinch of salt.
The main (only) point of debate between responsible sceptics and AGWers concerns feeback. Sceptics think it’s likely to be small or even negative – AGWers think it will be large and positive.
David A says “ Carbon dioxide contributes 10% of the effect so that is 3° C . This is rubbish. Jack Barrrett, a leading expert in spectroscopy – and a sceptic (see ) reckons the effect of CO2 is more like 9 deg (see the link to his paper on Warwick Hughes site). In fact David Archibald’s own graphs suggest his numbers are wrong. The Modtran plots show the net downward forcing increasing by ~25 w/m2 (~235 w/m2 -> ~260 w/m2) due to the current concentration of CO2.
Is David saying that 25 w/m2 only equates to a 3 deg rise?
How does that square with his claims that weaker solar output will result in a temperature decline of ~2 deg over the next “few years”. TSI measurements show that the sun’s output varies by ~0.1% or ~0.24 w/m2 at the earth’s surface.
In this WUWT post, Richard Lindzen estimates 1 deg increase from a doubling of CO2
Here, Jack Barrett calculates an increase of ~1.3 deg
There are many other reputable (not AGW) scientists who say much the same. If the feedback effect is small (or negative) then we don’t have a problem and it’s quite possible that natural variation will ‘hide’ most of the effect. CO2 will, though, have an effect. There are also very good reasons that continuing to add CO2 will not, as David says result in the effect being ‘tuckered out’, but result rather in indefinite warming. I’m not prepared to go into that now, though.

Steve Goddard

This effect is the opposite of a “tipping point.” More like a “disappearing effect.”

That CO2 forcing increases logarithmically with concentration has been known for over a century. Arrhenius (1896) did the necessary calculations:
“if the quantity of carbonic acid increases in geometric progression, the augmentation of the temperature will increase nearly in arithmetic progression”
The IPCC are well aware of this
“Note that for CO2, RF increases logarithmically with mixing ratio” (AR4 WG1 chapter 2.3.1)
and this knowledge is implicit in all the model projections. To imply otherwise is disingenuous.
Graph 4 is simply wrong. The bar chart is warming per 20ppm increase in CO2 concentration, the line is the cumulative effect. The units of these two parts are different – the first is deg C/ppm, the second is deg C. They are incomparable.
That problem is fixed in the last plot: at least the units are the same in this figure. But there is a second problem. The natural CO2 forcing is shown without any feedbacks, whereas the anthropogenic forcing is shown with feedbacks. This is misleading. Nobody would argue that the natural changes in CO2 are not magnified by feedbacks (try to explain the glaciations without feedbacks) One can argue about the magnitude of the feedbacks. Perhaps the IPCC has them too high. Perhaps too low.

Steve Goddard

Richard Telford,
Are cloud feedbacks positive or negative?
How is it that earth’s temperature has remained in a narrow range for 600 million years, despite 2000% changes in CO2 concentration?


As a non-scientist, can anyone please explain why there is no convective heating
of the atmosphere? Are thermals due entirely to CO2 in the deserts?

wes george

Thank you, David. This one simple fact has not been repeated often enough. Dare I say it has been suppressed in the mainstream debate.
I know that most disinterested people I talk to are under the impression driven by media alarmists that as atmospheric CO2 levels increase the temperature follows in a linear, if stochastic, fashion. That is the single greatest myth behind AGW demagoguery.
Watts and others should repeat some version of this post once a month for the next decade. It can not be stated often enough!

John Finn

ginckgo (04:03:44) :
So a doubling of CO2 relative to pre-industrial times leads to an increase of 2W/m2. The difference between the solar minima and solar maxima IIRC is about that much.

The doubling of CO2 relative to pre-industrial times leads to an increase od ~3.7 w/m2. When looking at the difference between soalr minima and maxima you need to look at insolation, i.e. what the earth receives, not TSI. If TSI increases by 2w/m2, the earth’s surface, on average, only receives 25% of this (think day, night, winter, summer). Of that ~30% gets reflected back to space due to the earth’s albedo. A 2 w/m2 increase in TSI equates to an increase of ~0.35 w/m2 averaged over the earth’s surface. You should take a bit more notice of Dr. Leif Svalgaard’s posts and it a little less of Dr. David Archibald’s.

Or alternatively one could be to look to ‘natural causes’. One of the better proxies is GMF (geomagnetic field)
which not necessarily mean that GMF is either the cause or a consequence, but possibly two offsprings of the same parentage.


Let’s see, usually we are told by AGW skeptics that the atmosphere is too complex to understand. That the sophisticated mathematical models that run on supercomputers cannot possibly come close to the real climate. But, now we are to believe that some guy with a graphing calculator has got it all figured out! He didn’t even need calculus, just an ln x button. Think of all the tax dollars that could have been saved!


I have been on the receiving end of proponents’ reply to the temperature changes mentioned in the above post.
The counter argument is that we need to make a distinction between the “equilibrium” climate sensitivity, and “transient phase”. We are suppiosed to be in the transient phase at the moment, and it is argued that the climate will take centuries to settle to equilibrium. According to this argument, we would not expect to see the equilibrium conditions for a long time to come.
I have not found this to be convincing.
Even if we were to accept that the present condition is the transient en route to a much higher equilibrium, the transient should still be evident in measurement. IPCC AR3 Chapter 9 has a beautiful chart of the “big red spot”, which show how atmospheric heating above the surface is necessary to observe heating at the surface (if heating is due to radiative physics). We should be able to see the red spot forming by now (transient or not) – especially if some past warming has been attributed to CO2.
I know of no confirming measurements which do so. Some people claim that cooling in the ionosphere is evidence – but cooling in the ionosphere without warming further down does nothing to explain recent warming. In the absence of such evidence, I’d look upon the hypothesis as falsified.
Secondly, what I consider to be the unphysical argument of amplification of temperature change by positive feedback. The term “amplification” means a dimensionless constant, where a change of an input variable results in a greater change of an output variable with the same dimensions. In the case of climate sensitivity, we’re talking about units of temperature or units of radiative flux at the surface (take your pick), where a change of input results in some multiplied change, when the system eventually settles to equilibrium.
Given that amplification is dimensionless, it’s clear that there is an increase of energy from the input to the output. We need to identify and account for this energy to make a convincing case for amplification in climate sensitivy.
And this applies equally to feedback systems – without an “auxiliary” source of energy, feedback cannot amplify a signal. Trying to say it does would be like arguing that I could jump into a basket and lift myself off the ground using the handle. You might get that to work in the cyberworld of computer models, but it doesn’t work in the real world.
I’m not trying to say that amplification is wrong. I just haven’t seen the full explanation of energy flows, so references would be welcomed. And until I see this, I would tend to view amplification of the climate sensitivity as another falsified hypothesis.

David Archibald

There is no need to rehash the science. Real Climate attacked my graph back in October 2007 in a piece entitled “My model, used for deception”.
That was the seal of approval. Real Climate felt they could no longer ignore it, they had to try to counter it. Thanks guys. Without that sort of feedback, you don’t know how effective you are.
There are two sorts of IPCC scientists – the ones that fake the historical record and the modellers who generate warmings for a doubling of CO2. We hear a lot about the former but the latter are required to give credence to the alarmist projections. Looking at a graphic that Roy Spencer produced in early 2008, there are 21 model results contributing to the IPCC concensus, with the lowest warming 2.5 degrees and the median 3.5 degrees.
But it had been bugging me for a while that global warming belief system has their heating from the pre-industrial level, and not some other point. Never mind that Spencer has shown that the feedback is negative, not positive. What the AGW belief system requires is that the system is quiescent up to the pre-industrial level and then it just explodes. It requires everybody to believe in fairies at the bottom of the garden. It defies the laws of physics and nature. It is the big lie upon which the whole AGW edifice is founded.

Bill Tuttle (02:43:21) :

Richard Telford (01:00:29) :
I don’t know if this post was supposed to be misleading and confusing but is certainly is.
Forcing is logarithmic! Surprisingly, climate scientists were aware of that.
Then why do their models produce an algebraic [arithmetic] result?

I think some of the answer is that if CO2 are climbing exponentially, then the log() of that is a straight line. The catch is that current CO2 levels can better be modeled, I believe (i.e. no references and I wouldn’t believe this if I were you), as a baseline plus an exponential. The log() that is quite a bit
flatter until the exponential overwhelms the baseline.

OT, but being the science blog, some of you may find these interesting, I think they are fascinating (to see next position cursor over the photo).