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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The earth’s temperature has stayed between 12C and 22C for hundreds of millions of years. Is that a true assumption? If true, wouldn’t a strongly negative feedback system having dead-band model it? Such a feedback system would servo to 290 deg K with a +/-5 deg K dead-band (non-linear region) .
AC (13:00:32) :
Larry, Jay, John Finn, RockyRoad, and others who have discussed positive and negative feedback mechanisms:
Is there anything logically wrong with the following AGW position?
1) There are natural negative feedback mechanisms to absorb CO2.
2) These negative feedbacks kept CO2 in check and/or reduced CO2 from previous extremes without causing a runaway hot earth (unchecked positive feedback).
3) The negative feedbacks are now being overwhelmed by man made emissions that are increasing CO2 dramatically faster than in the past.
E.g., something along the lines of what’s being said here:
http://climateprogress.org/2008/04/28/human-driven-co2-rise-14000-times-faster-than-nature-overwhelming-the-slow-negative-feedbacks/
These feedbacks are referring to specifically to the growth of CO2. It could actually be argued that there are both positive and negative feedbacks here. For example, the amount of CO2 produced by fossil fuel burning adds is equivalent to ~3.5 ppm but only ~2 ppm is being added each year. It seems as thoughthe system is responding and at least partly offsetting the increase.
However the CO2 feedbacks (+ve or -ve) simply determine whether we’ll double the pre-industrial level in 2050, say, or 2070 or even 2100. The feedbacks referred to earlier by myself relate to the forcing feedbacks at a given concentration of CO2. It is these feedbacks where there is disagreement. To explain:
If CO2 doubles from 300 ppm to 600 ppm then radiative transfer calculations suggest that this will cause the earth to warm by a bit more than 1 deg. That’s the basic temperature rise due to CO2 alone. Now then, because the surface and atmosphere is warmer it’s possible that increased evaporation will occur. Also a warmer atmosphere can hold more moisture (water vapour) which might mean that the greenhouse effect is amplified further (water vapour is a ghg) and so we get further warming in addition to that from CO2 alone. That is a simplified explanation of why climate models get warming of 3 deg per CO2 doubling. However, the assumption seems to be that all the extra water vapour goes into warming the planet. I’m not convinced by this.
Thanks for the analysis.
I first became convinced that AGW is greatly exaggerated when I found out it relies on positive feedback to magnify any forcing by at least 3. That should surely have meant the earth would have shot off to an extreme, never to return, ages ago. The earth would be either permanently frozen, or boiling hot, unless the forcings were miraculously minute. A volcano would have led to an ice age. The heat from a major asteroid hitting earth would have made the earth being boiling hot for ages.
I started to say in a previous comment that assuming a magnification of 3 times due to feedback is incompatible with a relatively stable system like the earth’s climate, and started to analyse the effect of feedback combined with a logarithmic forcing due to CO2. Someone pointed out that the effect of CO2 can’t be logarithmic since ln(0) is negative infinity. I would say that it’s approximately logarithmic over a wide range where we are, but goes to a very small linear effect at low concentrations. If there was one molecule of CO2 in the atmosphere, and you added a second, the effect would be almost exactly linear since the second order effects would be tiny.
It now seems that the feedback reduces the change to maybe 1/3 of the forcing. Even if there was no feedback opposing changes, ignoring the relatively stability of the earth’s climate, even if we could double the CO2 in the air before it dissolved in the oceans or we went to nuclear power etc, that would mean a rise of about 1.2 degrees Celsius. I think that would make the world a better place, more like the prosperous medieval warming than the cold times of the Great Famine and the Little Ice Age.
When we have accurate temperature measurements over the last century, without “artificial adjustments” and “normalisation”, this would be an interesting calculation:
Calculate the forcing due to CO2 over the last 100 years.
For various assumed feedback magnifications of forcing, calculate the effect of CO2.
Subtract the effect of CO2 from the measured temperatures to get the temperature as determined by natural variation.
Compare the calculated variation for the various assumed magnifications.
The AGW theory is that natural variation is small and CO2 effects are large and dangerous.
Given that it cooled from about 1940 to 1970 when industry got going, and then cooled from 1998 to 2010 when CO2 production was at it’s maximum, I’m sure that large positive magnifications would need more natural variation to fit, and that negative feedback with say 1/3 magnification would need much smaller natural variation. In other words, scary scenarios for the future need a large positive feedback but that’s incompatible with the actual temperatures and CO2 of the 20th century.
George E. Smith (11:32:44) :
George E. Smith (12:42:22) :
Thank you for elucidating so clearly fact that CO2 hypothesis is fallible. Considering the light’s electromagnetic wave properties, the CO2 absorption and radiation account, in the ‘light’ of spectrum’s wavelengths and atom’s energy levels, may be as instructive.
Thanks again.
Smokey (14:22:46) :
You miss the point I was making. I wasn’t suggesting that the ‘Beck’ measurements were wrong or inaccurate I was suggesting they were taken from different locations and so were inconsistent and from locations that were inappropriate.
They are useless in providing any comparsion to the current well-mixed levels. Here’s an example from an Excel file of Beck’s data.
In 1843 CO2 was 308.6 ppm
In 1844 CO2 was 400 ppm
Now it’s quite possible these were both highly accurate readings but I doubt if they were taken from the same location. If we took a measurement from the centre of London or Paris or New York I’m sure it would be well in excess of 400 ppm but it would not be representative of global CO2 concentrations.
Mike J (13:37:49) :
@ur momisugly P Gosselin (02:19:05) : “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?”
You ask a good question. A quick search came up with the following, although it is only 3.6% rather than 10…. Hope it helps.
It doesn’t – it’s nonsense.
Oh, great. Another pseudoscientific article. If someone shows me that net downwards forcing (backradiation) is an observed property of the atmosphere, I’ll show a fraudulent representation of physics.
Also CO2 is NOT a strong absorber of IR. CO2 is much poorer at absorbing heat than air. The rate of emission of CO2 is inversely proportional to its rate of absorption. CO2 temperature always LAGS dry air when equal volumes are heated (with CO2 at 100% concentration). CO2 is a poor absorber of heat period. Compared to water vapor CO2 is insignificant to do anything but provide life to the biosphere.
“AC (13:00:32) :
Larry, Jay, John Finn, RockyRoad, and others who have discussed positive and negative feedback mechanisms:
Is there anything logically wrong with the following AGW position?
1) There are natural negative feedback mechanisms to absorb CO2.”
This is not the way a negative feedback works. A negative feedback simply produces an input to the system with the opposite polarity of the output, and depending on the strength of the negative feedback this might reduce amplification or null it altogether. An example would be: Rising CO2 level leads to a fall in humidity according to F. Miskolczi’s theory. But the physical mechanism is not that important: Important is that negative feedback can be independent of absorption of CO2.
“2) These negative feedbacks kept CO2 in check and/or reduced CO2 from previous extremes without causing a runaway hot earth (unchecked positive feedback).”
The effect of a negative feedback can be what you described here.
“3) The negative feedbacks are now being overwhelmed by man made emissions that are increasing CO2 dramatically faster than in the past.”
A simple linear negative feedback is proportional to the output of the system, so the stronger the output rises, the stronger the negative value fed back. So, no, it can’t be overwhelmed.
Of course the feedback might be nonlinear, might have a time lag associated with it (in a physical system the size of the earth, probably a noticeable one on the order of at least days if not months, years or decades), might be a logarithmic response etc…
It’s difficult to say without a model of a physical mechanism. The AGW scientists have never talked much about negative feedbacks or i didn’t listen, i always hear “positive feedback” from them… Miskolczi, Lindzen, Eschenbach have described negative feedback mechanisms.
For a stable system, the negative feedback must have an amplification factor between 0 and -1 i would say; a greater negative value would lead to rapid and amplifying oscillations (ever greater extremes, which we don’t observe).
A consequence would be that the input perturbation – the warming of the surface through increased CO2 – would not be entirely compensated: The output of the system must be perturbed slightly to be able to feed back a compensation value. So a negative feedback close to -1 would lead to a near-compensation of the “warming due to increased CO2 ‘forcing'”, but not compensate it completely.
(My usual model of a negatively fed back operational amplifier – i don’t know whether any “credible climatologist” (of the Hansen school of thought, i hope that is not taken as an insult) ever thought about it this way; or whether they even know about negative feedbacks)
HTH
I keep reading that greenhouse gases are the reason the average temperature of the Earth is approximately 33 degrees K (or C) higher than the average temperature would be in the absence of greenhouse gases. Just like Juraj V. (06:54:22), I find this hard to believe. My reasons for disbelief are as follows.
(1) I’ll assume the average temperature of the Earth is 15 degrees C or 288 degrees K. Subtracting 33 degrees C gives a temperature of -18 degrees C or 255 degrees K. Thus, for greenhouse gases to warm the Earth 33 degrees C, the average temperature of the Earth in the absence of greenhouse gases must be 255 degrees K.
I believe the argument for a “greenhouse-gasless” average Earth temperature of 255 degrees Kelvin is based on five assumptions: (a) the Earth’s surface acts like a “grey body” absorber/radiator, (b) the temperature of the surface of the Earth is everywhere the same (both day/night and at all latitudes/longitudes), (c) the average albedo of the Earth is approximately 0.3–which implies an average absorptivity of approximately 0.7, (d) the emissivity of the Earth is unity, and (e) the Earth exists in a directional electromagnetic radiation field having a power density of approximately 1,367 Watts per square meter. The computation of the power absorbed by the Earth is the product of (i) the incident power density, (ii) the average Earth absorptivity, and (iii) the cross-sectional area of the Earth (pi times the radius of the Earth squared). The computation of the power radiated by the Earth is the product of (i) the temperature of the Earth in degrees Kelvin to the fourth power, (ii) the surface area of the Earth (4 times pi times the radius of the Earth squared), (iii) the Stefan-Boltzmann constant, and (iv) the average Earth emissivity. Setting these two powers equal and solving for temperature one gets approximately 255 degrees K for the temperature of the Earth.
A critical flaw with this approach is that for thermal radiation from “grey body” surfaces, the principle of detailed balance (which is a qualitative form of Kirchoff’s law) requires that the emissivity and the absorptivity of a surface be equal. Thus, it is inappropriate to simultaneously use an absorptivity of 0.7 and an emissivity of 1. When the preceding model is used with the single change that the average absorptivity equals the average emissivity, the Earth’s temperature is approximately 278 degrees K, not 255 degrees K; and provided the absorptivity is not zero, the temperature is independent of the absorptivity.
This still leaves 10 degrees C to be accounted for; but not 33 degrees C as is often claimed.
(2) Then like Ron E Seal (06:28:48) and Ken Coffman (07:05:02) have pointed out, the presence of an atmosphere (greenhouse or otherwise) will have an effect on the Earth’s average temperature. In the first place, the surface of the Earth can no longer be treated as a “grey body” radiator. Electromagnetic radiation through and by gases voids the use of grey body radiation laws–conduction and convection must be taken into account. I believe such computations are extremely complex–especially for a non-inertial (rotating) Earth. As such, it seems eminently reasonable that an atmosphere like the Earth’s but devoid of all greenhouse gases might raise the average surface temperature of the Earth 10 degrees C above what it would be in the absence of an atmosphere.
Bottom line, I see little or no justification in Mr. Archibald’s statement: “The greenhouse gasses keep the Earth 30° C warmer than it would otherwise be without them in the atmosphere…“
Hmmm … I sometimes wonder if these posts (head post + ensuing discussion) aren’t some sort of over-all general competency test … doing a word-search on the volume of text and posts above, I found zero mention of the following terms WHICH underpin the of physics of ‘radiational forcing’ that CO2 (and H2O vapor) are intimately involved insofar as the surface-to-space energy budget.
“Atmospheric window” – an area in/about 10 um that enjoys a clear view from surface to space (save for moderate to heavy overcast/clouds). Coincidentally, the ‘warm earth’ produces a spectral peak in the Planck curve in this atmospheric window especially as warmer earth surface temperatures. The spectrum either side of this window are bracketed by (variable amounts of) water vapor and CO2 absorption (which also serve to determine how wide this ‘window’ ultimately is)
“Planck’s curve” – a curve denoting wavelength versus spectral emission (radiation, as a verb) strength. Notably, the spectral energy in this curve is proportional to Temperature to the 4th power.
“Wein’s Law” – calculates where the peak wavelength occurring in Planck’s curve, which for a 288 to 290 K earth peaks in/about 10 um wavelength atmospheric window (see above)
I note that MODTRAN is used in the first graph to depict ‘net downward forcing’ energy; MODTRAN can also be used for calculating ‘upwelling’ LWIR radiation from the earth’s surface should internally be using Planck’s Law and the ‘spectral opening’ at 10 um to determine the energy budget/energy flow into space
An interesting experiment of the student: Using MODTRAN plot David Archibald’s graph axis for CO2 (ppm) versus a fixed earth surface temperature; (is IT, the resulting func logarithmic? what does a delta change in temperature vs total W/m2 upwelling LWIR look like?)
.
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Re: Percentage contribution from CO2 to greenhouse effect.
Ididn’t particualrly want to get into this but here goes anyway.
Because of overlaps in the absorbing spectra, calculating the effect any particular gas is not straightforward. The best way to illustrate this is to look at a hypothetical case or thought experiment.
If CO2 were removed from the atmosphere while leaving all other ghgs at the same concentrations then we would be left with 91% of the current greenhouse effect. However, if all other ghgs were removed leaving only CO2 then 26% of the current greenhouse effect would remain. The CO2 contribution, therefore, is somewhere between 9% and 26% of the total. But (and it ‘s a big but) if we removed CO2 thus cooling the atmosphere it’s unlikely that the water vapour concentration would remain constant.
“AC (13:00:32) :
Example of +ve feedback as proposed by AGW
doubling CO2 from 280ppm to 560ppm = 3.7 watts/m2 extra juice “kept in”
3.7 w/m2 = +1 degree C
max water vapour about doubles with every +10 degree C
water vapour is a greenhouse gas
extra water vapour from +1 degree C = 7.4 w/m2
CO2 plus positive feedback = 3 degrees
(over simplification but you get the idea)
Example of -ve feedback
+3 degrees temperature rise
earth surface radiates power (in theory) = constant x T(degrees K) ^4
or P=C*T*T*T*T
so +3 degrees at 0 C = 14.3 w/m2
but +3 degrees at 20 C = 17.7 w/m2
so the warmer it gets, the FASTER the rate at which the earth sends heat to space goes up. Now it is of course much more complex than that, but it is easy to see that the +ve inputs can only raise temperature for so long before the -ve inputs overwhelm them.
Bravo, Reed Coray! It’s just amazing how many lapses in phyical reasoning are encapsulated in the usual, simplistic, radiation-only view of Earth’s thermodynamics. You’d think that those who call themselves climate scientists had never heard of enthalpy or understand that evaporation from the oceans necessarily cools the surface. All this without even touching the misguided notion of “positive feedback.”
One of the things I’m finding interesting about this thread is that Dr. Svalgaard has not yet turned up to give a thump to Dr. Archibald. One of these days those two Renaissance Men will get together on something they agree on and set us all back on our heels. I’m waiting for the day. In the mean time, I sit and learn.
John Finn (14:48:33) :
“Also a warmer atmosphere can hold more moisture (water vapour) which might mean that the greenhouse effect is amplified further (water vapour is a ghg) and so we get further warming in addition to that from CO2 alone. That is a simplified explanation of why climate models get warming of 3 deg per CO2 doubling. However, the assumption seems to be that all the extra water vapour goes into warming the planet. I’m not convinced by this.”
See my comment at 12:41:13. If there is a logarithmic relationship between temperature increase and concentration of water vapor, then how could any small addition of water vapor caused by the additional heat from CO2 be significant?
I agree with your last two sentences quoted above. I think folks l
”
Bill S (13:20:36) :
I was reading here ( http://www.aip.org/history/climate/simple.htm ) that viewing the atmosphere as a series of distinct layers as opposed to as a single “slab” increases the likelihood that adding more CO2 will cause more radiative absorption. If CO2 doesn’t “capture” the outgoing radiation in one layer, a higher layer might do so, and still “trap the heat”.
The layer suggestion might hold up better in the stratosphere, but I know next to nothing about the stratosphere. Can anyone enlighten me in this area?
”
Bill, a multislab situation provides more accuracy because each has its own temperature, pressure, and gas concentrations. It doesn’t mean though there’s more chance to capture – in fact – it’s less. As pressure drops, the lines become narrower so there’s less energy that can be collected. Also, each slab has far less material than the whole so there’s still only so many molecules of co2 between here and the top of the atmosphere.
Another factor is that for the troposphere and most all of the stratosphere and thermosphere, there is radiation away from the slab as well as absorbed by the slab. In fact, the lapse rate is related to this as a conservation of energy. Lower down, when surrounded by slabs above and below that are similar in temperatures, there is a bit of equilibrium going on – or so it would seem. Higher up, you’ve got all the radiation coming through the slab (in the LWR arena) coming from below. One can approximate with the stefan’s law grey body concept. Stefan’s law is for radiation in a hemisphere and there are two hemispheres – the outbound and the inbound. It’s got to radiate equally in both directions and the energy has to balance with what is absorbed, which is essentially only from below as you get higher – as there’s low lwr coming down so there’s got to be a T drop – unless there’s some additional energy coming in.
General comment – I am rereading Tommy Gold’s Deep Hot Biosphere and his chapter on the carbon cycle is now extremely relevant – put very simply, in order for life to exist on Earth, apart from having a massive atmosphere which ensures the presence of liquid water, CO2 is continually extracted from the atmosphere and precipitated into sediments, coral reefs etc. This requires a fresh source of CO2 that Gold proposes comes via the breakdown of hydrocarbons by a deep hot biosphere which then emits, mainly methane, and some CO2.
So the existence of life on the Earth’s surface that is dependent on photosynthesis for its existence, and consumes carbohydrates, actually relies on an even deeper biosphere that feeds on upwelling hydrocarbons whose metabolising products are methane and hence CO2 which feed the surface biosphere.
To paraphrase Obiwan Kenobi, we are in a symbiotic relationship with the deep hot biosphere, surely you must understand that! 🙂
”
Reed Coray (15:25:22) :
..
A critical flaw with this approach is that for thermal radiation from “grey body” surfaces, the principle of detailed balance (which is a qualitative form of Kirchoff’s law) requires that the emissivity and the absorptivity of a surface be equal. Thus, it is inappropriate to simultaneously use an absorptivity of 0.7 and an emissivity of 1. When the preceding model is used with the single change that the average absorptivity equals the average emissivity, the Earth’s temperature is approximately 278 degrees K, not 255 degrees K; and provided the absorptivity is not zero, the temperature is independent of the absorptivity.
This still leaves 10 degrees C to be accounted for; but not 33 degrees C as is often claimed.
(2) Then like Ron E Seal (06:28:48) and Ken Coffman (07:05:02) have pointed out, the presence of an atmosphere (greenhouse or otherwise) will have an effect on the Earth’s average temperature. In the first place, the surface of the Earth can no longer be treated as a “grey body” radiator. Electromagnetic radiation through and by gases voids the use of grey body radiation laws–conduction and convection must be taken into account. I believe such computations are extremely complex–especially for a non-inertial (rotating) Earth. As such, it seems eminently reasonable that an atmosphere like the Earth’s but devoid of all greenhouse gases might raise the average surface temperature of the Earth 10 degrees C above what it would be in the absence of an atmosphere.
Bottom line, I see little or no justification in Mr. Archibald’s statement: “The greenhouse gasses keep the Earth 30° C warmer than it would otherwise be without them in the atmosphere…“
”
Emissivity and the grey body assumption are an engineering approximation. In reality, one should expect the body to have emissivity and absorption by wavelength to be consistent at each wavelength. Note, incoming solar is for a planck curve of about 6000k and peaks around 500 nm. The albedo is 0.7. The Earth is radiating outward at a T of near 288k and it is radiating totally in the longwave IR. The effective emissivity is going to be approximately 1 at the lwr. Note too that the albedo of 0.7 is a combination of surface and cloud albedo and the actual average surface albedo is around 0.08 while the clouds contribute around 0.22 so in no way do you have a problem here.
One does have the problem of such things being radiative only – but then the idea is to conceptually explore the conditions associated with such. Around 100 w/m^2 is the convection and water vapor cycle. any increase in T results in increases of convection and evaporation. It’s not that big a deal to assume an average or typical value or look at radiative only as that is a best case (actually worst case) scenario for problems in transfer of heat. Since the surfac an d most Ts in the atmosphere are triple digit – 200-400 K, one also can deal more with pertubations than having to worry about individual calculations for every variation above or below the mean with T^4 rather than T.
The figure of 1DegC warming for a 3.5W/m^2 increase in Radiative Forcing (which the IPCC makes clear is a forcing at the Tropopause) is for the Tropopause area only.
At the surface, the sensitivity is between 0.095 and 0.15 DegC/W/m^2, depending on the assumption you make for evaporation (there is a wide range of views – the mainstream seems to lie between 2% and 6.5% increase per DegC).
So the same forcing translated to the surface would produce an extremely worrying 0.3to 0.5 DegC temperature rise, implying a 1% to 3% increase in water vapour.
To maintain the median IPCC forecast of 3DegC at the SURFACE, the implied conditons at the surface are:
1. Evaporation increased between 6% and 20%.
2. Surface Forcing increased by between 21W/m^2 and 32W/m^2
So we have the situation, according to the Proponents, that a doubling of CO2 causes a radiative imbalance of 3.5W/m2 at the Tropopause. This Radiative Forcing translates to an increase in Surface Forcing (at equilibrium- this is not a transient) of between 21-32W/m^2.
In detail, how is this increased forcing maintained? Where is the accounting of it, Watt by Watt?
The global warming theory does provide a number of testable hypothesis. Generally each component of the following assumptions can be tested. This may be a new explanation of global warming theory for some of you.
1) If CO2/GHGs double, there should be an increased forcing of 4.0 watts/metre2 at the tropopause emission layer which is now 255K or 240 watts/m2 (on average 5 kms up, not the surface);
2) If there is an increase of 4.0 watts/m2 at the tropopause emission layer, temperatures at that layer will increase by 1.2C (according to the Stefan Boltzmann equations).
3) If temperatures increase by 1.2C at the (former level of the) tropopause emission layer, water vapour will increase providing an additional indirect 4.0 watts/m2 of forcing.
4) If there is 8.0 additional watts/m2 of forcing at the tropopause emission layer, another 1.75 watts/m2 of indirect and surface albedo affects will appear in the long-run and (and another 1.75 watt/m2 of humidity forcing will result from those indirect effects) and, in total there will now be 11.5 extra watts of forcing at the emission layer.
5) If there is an extra 11.5 watts/m2 at the layer which was 255K or 240 watts/m2, temperatures at this layer will increase by 3.0C according to the Stefan Boltzmann equation.
6) If temperatures increase by 3.0C at the former level of the tropopause emission layer, the layer itself will increase in height by 461 metres. This newer higher emission layer will still be in equilibrium (over the long-term) with the solar forcing of 240 watts/m2.
7) If the tropopause emission layer is now 461 metres higher, and if the adiabatic lapse rate of 6.5C/km stays constant, the surface temperature will now increase by the same 3.0C .
8) And thus we have 3.0C per GHG doubling of 4 watts/m2 (or a impact of 0.75C/watt/m2).
There is your global warming theory in a nutshell which is not really explained anywhere else like this that I have seen.
We can test all of these assumptions:
1) humidity levels are not increasing at the tropopause emission layer.
2) the adiabatic lapse rate should not be considered as a never-changing entity. The Stefan Boltzmann equations predict that it should increase slightly as the temperatures increase so that the surface should only warm by a little more than half of the tropopause.
3) I have never seen a proof of Myhre’s GHG doubling forcing estimates.
John Finn (15:43:17)
‘The CO2 contribution, therefore, is somewhere between 9% and 26% of the total. But (and it ’s a big but) if we removed CO2 thus cooling the atmosphere it’s unlikely that the water vapour concentration would remain constant.
That’s a “BIG IF” taking in the power of wind.
John Finn (04:44:49) : Thanks for your clarification. I was actually pointing out that, while people here seem quite happy to attribute fluctuations in the climate to solar cycles (and also the LIA), they don’t seem aware just how small the change in energy input needs to be to cause that change. As you point out, the increased energy retention brought on by CO2 doubling is actually bigger than the much touted “it’s the sun, stupid”.
Sergey (09:37:55) :
The very premise of this article that 30C increase in surface temperature is explained by greenhous effect is wrong. This difference is due to convection.
Thank you. Convection trumps radiative effects in every complex system. Why the effect seen in the backwards derivation of the magical properties of CO2 I don’t know.
Considering the history and persistance of this line of reasoning I don’t blame David for putting forward this intellectual argument.
There is only one comment I haven’t made yet and that is given the logarithmic effect of CO2, I suppose if we remove it from the atmosphere its effect goes to infinity 😀 … so like many have noted here, until I see some empirical experiment that shows something interesting and not some assumption laden model based derivation disguised as an experiment … the CO2 effect is ZERO in my mind and simply does not exist. It is only a small part of layers of a mixed gases of certain densities of the layered fluids that blanket the surface of the Earth and the phenomena we are observing should be renamed the ‘Blanket Effect’.
Ben W (05:57:46), HelmutU (06:44:57) and a number of other comments seem to have hit on the biggest problem with the CO2 graphs. David Archibald’s explanation of the diminishing logarithmic effect of CO2 is reasonable, however accepting claims of pre-industrial levels for CO2 of 280 ppm seems to have little foundation.
Splicing under sampled and inappropriate tree ring data to cherry picked UHI contaminated surface station readings produced temperature graphs showing “unprecedented warming”. These were offered as valid reconstructions by advocate scientists who intentionally hid the divergence between the two sets of rubbish data where they overlapped.
Splicing ice core readings from CO2 poor areas of the planet in which CO2 is not evenly mixed in the atmosphere with modern readings taken from the side of an active volcano produced graphs showing rapid increases in CO2. These were offered as valid reconstructions by advocate scientists who have intentionally ignored the large number of direct chemical measurements from the last 200 years that diverged from their ice core proxy data.
Same “Climate Science”, different bucket.
Jan Pompe (08:34:26) :
Hi Jan,
I’m happy to see your name here!
Here’s a bit from John Christy on benefits of co2,
Gene