Paul Ostergaard writes via email:
Here is an interesting new paper that Miklos Zagoni has pointed me to via Judith Curry’s blog. This researcher in Germany has carried out a spectroscopic analysis of the impact of CO2 and other greenhouse gases’ contribution to warming.
It arrives (surprise!) at a value one seventh of the IPCC best estimate for Climate Sensitivity for a CO2 doubling. Looks intriguing at first blush…
The climate sensitivity CS as a measure for the temperature increase found, when the actual CO2-concentration is doubled, assumesCS = 0.41 ̊C for the tropical zone, CS = 0.40 ̊C for the moderate zones and CS = 0.92 ̊C for the polar zones. The weighted average over all regions as the global climate sensitivity is found to be CS = 0.45 ̊C with an estimated uncertainty of 30%, which mostly results from the lack of more precise data for the convection between the ground and atmosphere as well as the atmospheric backscattering…. The values for the global climate sensitivity published by the IPCC [3] cover a range from 2.1 ̊C – 4.4 ̊C with an average value of 3.2 ̊C, which is seven times larger than that predicted here.
Here is the link to the abstract:
http://meetingorganizer.copernicus.org/EGU2011/EGU2011-4505-1.pdf
The paper is being presented at the EGU General Assembly 2011 in Vienna.
Perhaps our WUWT readers can dissect this and see how well it holds up. It is important to verify if the paper’s methodology is sound.
===============================================================
How much CO2 really contributes to global warming? Spectroscopic
studies and modelling of the influence of H2O, CO2 and CH4 on our
climate
Hermann Harde
Helmut-Schmidt-Universität Hamburg, Germany
Based on the actual HITRAN’2008 database [1] detailed spectroscopic studies on the absorbance of the greenhouse gases water, carbon dioxide and methane in the atmosphere are presented. The objective of these investigations was to examine and to quantify with these newly available data the influence of these gases on our climate.
The line-by-line calculations for sun light from 0.1 – 8 m (short wavelength radiation) as well as those for the emitted earth radiation from 3 – 60 m (long wavelength radiation) show, that due to the strong overlap of the CO2 and CH4 spectra with the water vapour lines the influence of these gases is significantly reducing with increasing water vapour pressure, and that with increasing CO2-concentration well noticeable saturation effects are observed limiting substantially the impact of CO2 on the warm-up of the atmosphere.
For the water vapour, which in its concentration is considerably varying with the altitude above ground as well as with the climate zone, separate distributions for the tropes, the moderate zones and the polar regions are presented.
They are based on actual GPS-measurements of the water content in these zones [2] and are applied for calculating the absorbance in the respective regions. The vertical variation in humidity and temperature, in the partial gas pressures and the total pressure is considered for each zone separately by computing individual absorption spectra for up to 228 atmospheric layers from ground level up to 86 km height.
The propagation length of the sun light in these layers, which depends on the angle of incidence to the atmosphere and therefore on the geographic latitude, is included by considering the earth as a truncated icosahedron (bucky ball) consisting of 32 surfaces with well defined angles to the incoming radiation and assigning each of the areas to one of the three climate zones.
To identify the influence of the absorbing gases on the climate and particularly the effect of an increasing CO2- concentration on the warming of the earth, a two-layer climate model was developed, which describes the atmosphere and the ground as two layers acting simultaneously as absorbers and Planck radiators. Also heat transfer by convection between these layers and horizontally by winds or oceanic currents between the climate zones is considered.
At equilibrium each, the atmosphere as well as the ground, delivers as much power as it sucks up from the sun and the neighbouring layer or climate zone.With this model for each climate zone the temperature progression of the earth and the atmosphere is calculated as a function of the CO2-concentration and several other parameters like ozone and cloud absorption, short- and long-wavelength scattering at clouds as well as the reflection at the earth’s surface.
The simulations for the terrestrial and atmospheric warm-up show well attenuating and saturating progressions with increasing CO2-concentration, mainly caused by the strongly saturating absorption of the intensive CO2 bands and the interference with water lines. The climate sensitivity CS as a measure for the temperature increase found, when the actual CO2-concentration is doubled, assumesCS = 0.41°C for the tropical zone, CS = 0.40°C for the moderate zones and CS = 0.92°C for the polar zones. The weighted average over all regions as the global climate sensitivity is found to be CS = 0.45°C with an estimated uncertainty of 30%, which mostly results from the lack of more precise data for the convection between the ground and atmosphere as well as the atmospheric backscattering.
The values for the global climate sensitivity published by the IPCC [3] cover a range from 2.1°C – 4.4°C with an average value of 3.2°C, which is seven times larger than that predicted here.
studies and modelling of the influence of H2O, CO2 and CH4 on our
climate
Hermann Harde
Helmut-Schmidt-Universität Hamburg, Germany (harde@hsu-hh.de)
Based on the actual HITRAN’2008 database [1] detailed spectroscopic studies on the absorbance of the greenhouse
gases water, carbon dioxide and methane in the atmosphere are presented. The objective of these investigations
was to examine and to quantify with these newly available data the influence of these gases on our climate.
The line-by-line calculations for sun light from 0.1 – 8 m (short wavelength radiation) as well as those for the
emitted earth radiation from 3 – 60 m (long wavelength radiation) show, that due to the strong overlap of the CO2
and CH4 spectra with the water vapour lines the influence of these gases is significantly reducing with increasing
water vapour pressure, and that with increasing CO2-concentration well noticeable saturation effects are observed
limiting substantially the impact of CO2 on the warm-up of the atmosphere.
For the water vapour, which in its concentration is considerably varying with the altitude above ground as well as
with the climate zone, separate distributions for the tropes, the moderate zones and the polar regions are presented.
They are based on actual GPS-measurements of the water content in these zones [2] and are applied for calculating
the absorbance in the respective regions. The vertical variation in humidity and temperature, in the partial gas
pressures and the total pressure is considered for each zone separately by computing individual absorption spectra
for up to 228 atmospheric layers from ground level up to 86 km height.
The propagation length of the sun light in these layers, which depends on the angle of incidence to the atmosphere
and therefore on the geographic latitude, is included by considering the earth as a truncated icosahedron (bucky
ball) consisting of 32 surfaces with well defined angles to the incoming radiation and assigning each of the areas
to one of the three climate zones.
To identify the influence of the absorbing gases on the climate and particularly the effect of an increasing CO2-
concentration on the warming of the earth, a two-layer climate model was developed, which describes the atmosphere
and the ground as two layers acting simultaneously as absorbers and Planck radiators. Also heat transfer by
convection between these layers and horizontally by winds or oceanic currents between the climate zones is considered.
At equilibrium each, the atmosphere as well as the ground, delivers as much power as it sucks up from the
sun and the neighbouring layer or climate zone.With this model for each climate zone the temperature progression
of the earth and the atmosphere is calculated as a function of the CO2-concentration and several other parameters
like ozone and cloud absorption, short- and long-wavelength scattering at clouds as well as the reflection at the
earth’s surface.
The simulations for the terrestrial and atmospheric warm-up show well attenuating and saturating progressions with
increasing CO2-concentration, mainly caused by the strongly saturating absorption of the intensive CO2 bands and
the interference with water lines. The climate sensitivity CS as a measure for the temperature increase found, when
the actual CO2-concentration is doubled, assumesCS = 0.41°C for the tropical zone, CS = 0.40°C for the moderate
zones and CS = 0.92°C for the polar zones. The weighted average over all regions as the global climate sensitivity
is found to be CS = 0.45°C with an estimated uncertainty of 30%, which mostly results from the lack of more
precise data for the convection between the ground and atmosphere as well as the atmospheric backscattering.
The values for the global climate sensitivity published by the IPCC [3] cover a range from 2.1°C – 4.4°C with an
average value of 3.2°C, which is seven times larger than that predicted here.
Still based on a model I see. Still a better result than the IPCC.
All models depend on radiation as the prime heat loss from earth. It is not. The prime heat loss process is convection. proof being the large Cu and Cb clouds that build in the hottest parts of the planet where you can still get hail storms, still more proof of heat loss in the convecting air.
It’s models again.
I find it quite interesting, but I would also like to read the rebuttal.
regarding the awkward wording: In German people prefer the passive form, because they consider it more professional, while the active form sounds juvenile to them. Many Germans (including myself) find it very difficult to avoid the passive form when writing in English, and most are not even aware of this difference between the languages, as it is not being taught in school.
An interesting abstract. I hope the authors make the data and code available, in order that others can attempt to falsify the method or conclusions – this is how science is supposed to work.
Concerning politics however, this conclusion, if it cannot be falsified by “climate modellers”, would be catastrophic to the CAGW industry. I expect the sparks to fly!
I find it amazing that people and those responsible for these blogs place faith in an abstract submitted for a meeting that is not even held yet. a)It has not been presented to the meeting in Vienna. b)It has not been checked through any peer review. c) It is not even a paper submitted to a reputable journal. d)It remains unclear wether the analysis include the feedbacks that normal assessments in other papers and summarized by the IPCC includes. If you wish to pinch a hole in the consensus view of climate sensitivity, please apply some elements of scientific thinking, rigour and analysis.
ZZZ says: March 3, 2011 at 12:13 am
” If he’s correct, this could be a big “gotcha” for the standard IPCC climate models, because it would mean that the standard IPCC approach is “over-counting” the combined effect of CO2 and water vapor absorption by assuming that each gas is absorbs as if the other gas was not present instead of — as this author does — calculating how each gas takes away some of the radiation the other gas needs in order to reach its full greenhouse efficiency.”
No doubt the response would be to say: “the double counting has been dealt with by reducing the scale of the (think-of-anything-you-like-to-get-a-grant) climate multiplier, and the result would not significantly change if you took this model and simply used an adjusted (think-of-something-bigger-get-a-grant) climate multiplier
Water evaporation is endothermic. Negative feedback.
Catastrophic AGW RIP.
In effect the “feedbacks” are included. What the author is saying is that the water vapour is already acting as such a powerful greenhouse gas at the particular frequencies where CO2 absorbtion is relevant, that in fact the atmosphere is almost completely saturated with absorbtion gases at those specific frequencies and therefore the addition of further CO2 will have a negligible effect. So if additional CO2 has limited effect on climate due to saturation, the feedbacks will be irrelevant.
However, it is a simulation based on a computer model and has the same underlying flaws as all climate modelling using computers. In fact you can see here that you can use the same climate models but the initial assumption is only changed – in the IPCC they assume that the amount of IR being absorbed is a long way from the maximum possible, whilst in this research they claim we are already close to the maximum possible, when you consider the absorbtion due to water vapour.
Of course the question then simplifies to “Is there enough water vapour in the atmosphere to totally negate any additional absorbtion from CO2?”. What these researchers have done is looked in detail at the absorption lines for each molecule and then measured the level of each gas in the atmosphere at different points to calculate how close we are to saturation at least in terms of how the temperature at ground level will be affected.
It’s not an unreasonable thing to do but in the end it is just another opinion put in the form of algebra.
So to summarise, if zero feedback sensitivity were 1.0ºC per doubling, effect of water vapour and other factors is a negative feedback of just over 50%. Seems eminently reasonable if you overlay the last 50 years’ trend over the earlier years’ warming since the LIA. Indicates effect of CO2 (manmade and otherwise) about 0.2ºC so far.
However before we get excited someone with the relevant atmospheric physics knowledge needs to give it a good going over.
WOW
I was just writing this up on my own blog and it struck me how much of a body blow this will be for the warmists if it sticks. The single undeniable fact: the reason they call us “deniers” is that you can’t deny the evidence of the science that CO2 causes warming
Well, now it appears that you can deny over 50% of this “undeniable fact”.
If this paper holds water, then at the very least all the climate estimates halve. The policy implication is obvious: the rate of reduction of CO2 necessary is half that before, i.e. the “critical” time periods for any reductions are doubled, which now takes any concept of serious global warming or need for action well beyond the period of supposed fossil fuel depletion (my back of the fag packet if oil ran out in 30 years, and we started using coal, was that it would only last 60 years).
Climategate would be a mere splash compared to the overwhelming tsunami this paper could create.
Has the unsinkable Global warming Titanic hit its iceberg?
syphax says:
March 2, 2011 at 10:34 pm
Can we at least agree to perform calculations with a spherical earth?
A pedant responds: Wouldn’t it be better to use an oblate spheroid earth? 🙂
@Baa Humbug: Yes water vapour but not water vapour feedback, thats a difference! The author cant even comare two number (his 0,.4 with IPCC) so the study is likley nonsense.
OK, I have an experiment idea.
Suppose one was to build a hot-house (or use one at any farm that will let one use it) but don’t put a roof on it. Now, put very sensitive equipment in there and measure the CO2 levels and temperature. Once you have the levels and temperature measured, then double the amount of CO2 and see how that effected the temperature. The bottles of compressed CO2 needed could be inside the unit and at the unit’s temp to prevent the addition of CO2 from unduly effecting the inside temperature.
Has this been done?
Mike McMillan says:
March 2, 2011 at 11:23 pm
syphax says: March 2, 2011 at 10:34 pm
If someone published a paper that found a sensitivity of 5 degrees C, and the paper abstract included the phrase “considering the earth as a truncated icosahedron (bucky ball) consisting of 32 surfaces”, how well would that fly around here?
Not ideal, but it does eliminate rounding errors.
The modeling with 32 surfaces is to appease the “Flat-Earthers”
A CO2 question.
If the world’s CO2 level goes from 380 ppm to 420 ppm, how do we know what percentage of that is due to man’s various activities? Are we certain that CO2 would stay at some “perfect” all the time if there was no mankind?
A number for contributors have said that the Harde paper does not parameterise feedbacks?
My question is why should it? Most IPCC papers on climate sensitivity postulate a positive water vapour feedback,
yet measurements of the Earth’s atmosphere since 1948 show no such evidence.
See here http://icecap.us/images/uploads/SPECIFICHUMIDITYSINCE1948.gif
Actually, radiation is the only way the planet loses heat to outer space. Convection and evaporation move the heat around. In particular, they move the heat up through the atmosphere to a greater altitude where it can then radiate into space.
Given that something like thirty percent of the heat is removed from the earth’s surface (to higher altitudes) by evaporation and convection, and given that this isn’t particularly controversial, I would bet a week’s worth of coffee that the authors didn’t forget to include it.
The paper doesn’t seem to be any kind of paradigm change. Even the AGW folks will agree that catastrophic, runaway global warming can only happen because of positive feedback. They really have to prove that there is a plausible mechanism for global warming and they have to prove that it actually exists. Even though they haven’t proven the existence of such positive feedbacks, they will argue that this paper ignores those positive feedbacks. Otherwise, I suspect that they will not find much to quibble about (unless there is an obvious glaring error in the methodology).
Bottom line: This isn’t going to be the paper that convinces the AGW folks to fold up their tents and slip silently away into the night.
I like this paper.
Number one because I can understand where it’s coming from directly from the abstract.
Number two because I never liked the idea that an increase in CO2 which is said to cause a 1.2K rise in temperatures would cause feedbacks that would increase temperatures by between 0.6K and 3.6K, which to my mind is utter bunkum. This paper bypasses all that by including all greenhouse gasses, therefore the idea of feedbacks is nullified. If there were feedbacks to the extent we are told there are, it would be possible to enclose a lake in a biodome, fill it with CO2 and extract all the extra heat created as a result, profitably.
Although it uses a model, it is based on actual measurements of the greenhouse gasses at the various layers of the atmosphere, not some figures finessed to show the right message.
Ryan says: March 3, 2011 at 2:38 am
In effect the “feedbacks” are included. What the author is saying is that the water vapour is already acting as such a powerful greenhouse gas at the particular frequencies where CO2 absorption is relevant, that in fact the atmosphere is almost completely saturated with absorption gases at those specific frequencies and therefore the addition of further CO2 will have a negligible effect. So if additional CO2 has limited effect on climate due to saturation, the feedbacks will be irrelevant.
Are you sure?
There’s not enough in the paper for me to draw any conclusion about feedback. My assumption is that if the direct CO2 forcing gives 1C, the IPCC climate multiplier is 2-5x so if the new direct forcing is 0.45C then the overall expected temperature change on IPCC estimates would be 0.9 – 2.3C.
I presume what you are saying, is that because a lot of this presumed positive feedback is from H2O and additional absorption, then as the absorption by H2O has already been to some extent “double counted” then the multiplier itself will also reduce by perhaps 50%.
So, would this give e.g. if we assume a halving of feedback it would result in an overall new estimate of 0.45C – 1.1C of warming for a doubling of CO2
Ron Cram , aah, yes, the magical feedbacks. And what would they be … research grant funds?
It will be interesting to see how it holds up under scrutiny.
Robert of Ottawa,
Brilliant! Best description of feedbacks yet. ;^)
With reference to the finite element modelling: “…it does eliminate rounding errors” and “The modeling with 32 surfaces is to appease the “Flat-Earthers””.
No problem – just progressively increase the number of surface elements (by reducing thier sizes) until the results approach asymptotic convergence. All you need is a supercomputer (hint: the MET Office has one that is not doing much useful work nowadays – maybe they can borrow that?)
syphax says:
March 2, 2011 at 10:34 pm
32 surfaces approximating a sphere seems reasonable for this kind of analysis to me. What do you believe would be gained by using more surfaces? It isn’t computationally practical to use a perfect sphere, by the way, so all you can do is pick a smaller panel size to approximate your sphere.
This is an improved model which should give us a better estimate of climate sensitivity, but it is not a direct measure. The calculated sensitivities for the different regions are still “fudge factors” that allow the model to agree with observations. If the concentrations of CO2 are uniform globally, why should the actual reduction of OLR by CO2 vary between regions? I f the effect is measurable, it would show up at the poles where atmospheric water is at a minimum. My analysis does not show a statistically significant effect. Click on my name.
syphax says:
March 2, 2011 at 10:34 pm
If someone published a paper that found a sensitivity of 5 degrees C, and the paper abstract included the phrase “considering the earth as a truncated icosahedron (bucky ball) consisting of 32 surfaces”, how well would that fly around here?
Can we at least agree to perform calculations with a spherical earth?
Any idea how much difference it would make to the sensitivity calc? Or are you just nit-picking?