Yellow dot is the present day ppm CO2 and the Green dot is double present ppm CO2. NASA estimates CO2 was 300 ppm in 1910 and 400 ppm in 2015. Exhibit from Coe et al. with added information.
Consensus climate science asserts as given a difference of 33°K between earth surface temperature average 288°K and top of the atmosphere temperature average 255°K. It further claims that IR active gases in the atmosphere (so-called “greenhouse gases”) cause the entire 33°K by their absorption of IR emitted from the earth. A recent peer-reviewed paper took without challenging that presumption and proceeded to attribute the warming effect to the various GHGs: H2O, CO2, CH4, and N2O. The researchers are expert with measures of atmospheric radiation activity and use of the HITRAN database. The paper is The Impact of CO2, H2O and Other “Greenhouse Gases” on Equilibrium Earth Temperatures by David Coe et al. Excerpts in italics with my bolds. H\T Paul Homewood
Abstract
It has long been accepted that the “greenhouse effect”, where the atmosphere readily transmits short wavelength incoming solar radiation but selectively absorbs long wavelength outgoing radiation emitted by the earth, is responsible for warming the earth from the 255K effective earth temperature, without atmospheric warming, to the current average temperature of 288K. It is also widely accepted that the two main atmospheric greenhouse gases are H2O and CO2.
What is surprising is the wide variation in the estimated warming potential of CO2, the gas held responsible for the modern concept of climate change. Estimates published by the IPCC for climate sensitivity to a doubling of CO2 concentration vary from 1.5 to 4.5°C based upon a plethora of scientific papers attempting to analyse the complexities of atmospheric thermodynamics to determine their results.
The aim of this paper is to simplify the method of achieving a figure for climate sensitivity not only for CO2, but also CH4 and N2O, which are also considered to be strong greenhouse gases, by determining just how atmospheric absorption has resulted in the current 33K warming and then extrapolating that result to calculate the expected warming due to future increases of greenhouse gas concentrations.
The HITRAN database of gaseous absorption spectra enables the absorption of earth radiation at its current temperature of 288K to be accurately determined for each individual atmospheric constituent and also for the combined absorption of the atmosphere as a whole. From this data it is concluded that H2O is responsible for 29.4K of the 33K warming, with CO2 contributing 3.3K and CH4 and N2O combined just 0.3K. Climate sensitivity to future increases in CO2 concentration is calculated to be 0.50K, including the positive feedback effects of H2O, while climate sensitivities to CH4 and N2O are almost undetectable at 0.06K and 0.08K respectively. This result strongly suggests that increasing levels of CO2 will not lead to significant changes in earth temperature and that increases in CH4 and N2O will have very little discernable impact.
Discussion
Unlike water vapour, the mean CO2 concentration will remain constant at all atmospheric levels, although its density will reduce as altitude increases and pressure and temperature decrease. CO2 concentration however will vary considerably with location and with seasons, as biospheric photosynthesis removes substantial seasonal amounts of CO2 from the atmosphere. A mean level of 400ppm has been assumed for the following calculations of atmospheric absorptivity. Similarly, CH4 and N2O concentrations will be considered to remain constant at current average levels of 1.8ppm and 0.32ppm respectively.
CH4 and N2O are indeed very powerful absorbers of infra-red radiation. Increasing the concentrations of each gas to 30ppm (a 16fold increase in the case of CH4 and an almost
100fold increase in N2O) would result in a combined absorption of 15%, close to the value of 18% for 400ppm of CO2. The combined absorptive impact in the presence of
H2O and CO2 however reduces this absorption to less than 3% as can be seen in Figure 11 due to the overlap of the absorption bands of CO2 and H2O. It would thus take a huge increase in atmospheric concentrations of these gases to have any significant impact on total atmospheric infra-red absorption.
Figures 4, 5 and 6 show the transmission of the spectral radiation Eλ, through current atmospheric concentrations of CO2 and H2O and through the combination of the two gases. Absorptivities of both CO2 and H2O, as well as CH4 and N2O, have been determined over the range 3 to 100µm to a resolution of 0.1cm-1. It is clear that significant amounts of radiated energy are absorbed by both CO2 and H2O. It is also clear that there is considerable overlap of the absorption bands of CO2 and H2O with the H2O absorption being the dominant factor.
Coe et al. Figures 4, 5 and 6.
It is of some interest to calculate the increase in temperature that has occurred due to the increase in atmospheric CO2 levels from the 280ppm prior at the start of the industrial revolution to the current 420ppm registered at the Mona Loa Observatory. (K. W. Thoning et. al. 2019) [17]. The HITRAN calculations show that atmospheric absorptivity has increased from 0.727 to 0.730 due to the increase of 140ppm CO2, resulting in a temperature increase of 0.24Kelvin. This is, therefore, the full extent of anthropogenic global warming to date.
Conclusions
From this it follows that the 33Kelvin warming of the earth from 255Kelvin, widely accepted as the zero-atmosphere earth temperature, to the current average temperature of 288Kelvin, is a 29.4K increase attributed to H2O, 3.3K to CO2 and 0.3K to CH4 and N2O combined. H2O is by far the dominant greenhouse gas, and its atmospheric concentration is determined solely by atmospheric temperature. Furthermore, the strength of the H2O infra-red absorption bands is such that the radiation within those bands is quickly absorbed in the lower atmosphere resulting in further increases in H2O concentrations having little further effect upon atmospheric absorption and hence earth temperatures. An increase in average Relative Humidity of 1% will result in a temperature increase of 0.03Kelvin.
By comparison CO2 is a bit player. It however does possess strong spectral absorption bands which, like H2O, absorb most of the radiated energy, within those bands, in the lower atmosphere. It also suffers the big disadvantage that most of its absorption bands are overlapped by those of H2O thus reducing greatly its effectiveness. In fact, the climate sensitivity to a doubling of CO2 from 400ppm to 800ppm is calculated to be 0.45 Kelvin. This increases to 0.50 Kelvin when feedback effects are taken into account. This figure is significantly lower than the IPCC claims of 1.5 to 4.5 Kelvin.
The contribution of CH4 and N2O is miniscule. Not only have they contributed a mere 0.3Kelvin to current earth temperatures, their climate sensitivities to a doubling of their present atmospheric concentrations are 0.06 and 0.08 Kelvin respectively. As with CO2 their absorption spectra are largely overlapped by the H2O spectra again substantially reducing their impact.
It is often claimed that a major contributor to global warming is the positive feedback effect of H2O. As the atmosphere warms, the atmospheric concentration of H2O also increases, resulting in a further increase in temperature suggesting that a tipping point might eventually be reached where runaway temperatures are experienced. The calculations in this paper show that this is simply not the case. There is indeed a positive feedback effect due to the presence of H2O, but this is limited to a multiplying effect of 1.183 to any temperature increase. For example, it increases the CO2 climate sensitivity from 0.45K to 0.53K.
A further feedback, however, is caused by a reduction in atmospheric absorptivity as the spectral radiance of the earth’s emitted energy increases with temperature, with peak emissions moving slightly towards lower radiation wavelengths. This causes a negative feedback with a temperature multiplier of 0.9894. This results in a total feedback multiplier of 1.124, reducing the effective CO2 climate sensitivity from 0.53 to 0.50 Kelvin.
Feedback effects play a minor role in the warming of the earth. There is, and never can be, a tipping point. As the concentrations of greenhouse gases increase, the temperature sensitivity to those increases becomes smaller and smaller. The earth’s atmosphere is a near perfect example of a stable system. It is also possible to attribute the impact of the increase in CO2 concentrations from the pre-industrial levels of 280ppm to the current 420ppm to an increase in earth mean temperature of just 0.24Kelvin, a figure entirely consistent with the calculated climate sensitivity of 0.50 Kelvin.
The atmosphere, mainly due to the beneficial characteristics and impact of H2O absorption spectra, proves to be a highly stable moderator of global temperatures. There is no impending climate emergency and CO2 is not the control parameter of global temperatures, that accolade falls to H2O. CO2 is simply the supporter of life on this planet as a result of the miracle of photosynthesis.
Footnote:
Coe et al. confirm what Ångström showed experimentally a century ago. He stated in 1900:
“Under no circumstances should carbon dioxide absorb more than 16 percent of terrestrial radiation, and the size of this absorption varies quantitatively very little, as long as there is not less than 20 percent of the existing value.” See Pick Your A-Team: Arrhenius or Ångström
Independently, W. A. van Wijngaarden, W. Happer published findings this year similar to Coe et al. in their study Relative Potency of Greenhouse Molecules
Science Matters 
Whenever I hear the word consensus, I know it’s probably a boatload of cr#p, especially regarding science and very intricate systems, like the Big Bang Theory, which doesn’t have an ounce of verifications. Regarding things like universe beginnings, how life began, and global anything, the scope of study and current information requires honesty and ongoing study, but I would suggest, there are things we will never know during human existence. Still worth the study, for in study, we learn, and there are applications. ** Regarding man-made global anything, we simply don’t know enough, for even if the Earth were to warm, and it hasn’t, not to any provable degree, for the Earth and Universe goes through cycles, we don’t know what any warming would result: good, bad, or something in between, perhaps even necessary for other changes that lead to more life. Just sayin.
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Thanks dw for your POV. In the present social discourse, it has become almost impossible to seek the truth, because there is so much power and money to gain by declaring science is settled. As one political commentator put it: When a politician speaking about a scientific matter says the debate is over, you can be sure of two things: the debate is raging and he is losing.
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Reblogged this on Climate Collections.
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The thing is, as we’ve always maintained, to think for yourselves. That’s a heavy responsibility, requiring thought, due consideration, and research, but also an unwillingness to part from principle. As Washington shared, the price of freedom is eternal vigilance, which means never accepting anyone’s word because of the “expert” title. No one is an expert.
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The paper linked here is all based on a mathematical mistake. The trick of this paper lies in equation 2. They claim that the temperature of the earth can be determined by a formula involving the product of the no-reemission atmospheric absorption (a), with some number n. Then they use the current temperature and current value of a with this formula to calculate n. Finally, they claim n is a constant. Great! Now they have a formula to calculate the earth’s temperature when a changes. Just multiply a times n and plug it into the formula.
Unfortunately this reasoning is completely wrong. There is no reason at all to believe that n is a constant with no influence from other variables. Their reasoning is no better than the following:
I postulate a formula that the mean global temperature is equal to the number of pirates p, times the temperature per pirate x. The current number of pirates on earth is 200 and the mean temperature is 290 K, so x=1.44. We assume x is a constant. Therefore, if the number of pirates increases to 300, the temperature will increase to 300*1.44=432 K.
Just like theirs, my formula is right, at least currently. The mean temperature really is 1.44 times the number of pirates, right now. The problem is assuming this formula will still hold true as conditions change. In particular, you can’t assume x is a constant.
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Thanks for commenting samh. That equation factor is explained thus:
“The effect of an atmosphere of infra-red absorbing gases is
that some of the emitted radiation will be absorbed by the
atmosphere. Let “a” be the total radiative absorptivity of the
atmosphere. The energy absorbed will be a∙R and the energy
transmitted through to space will be (1 – a)∙R. What happens
to this absorbed energy? Some will be retained by the
atmosphere/earth system and some will be reradiated by the
atmosphere through to space. Let “n” represent the “energy
retention factor”, the fraction of the absorbed energy a∙R that
is retained by the atmosphere/earth system, so that the fraction
transmitted to space is (1 – n)∙a∙R.”
The values are constrained by the requirement to match the TOA 255K temperature.
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Thanks for having the comment.
Indeed, the authors have not directly proposed an overly simple formula for the temperature. Instead they have recognized temperature is determined by radiative forcing at the surface (largely true), and then proposed an overly simple formula for radiative forcing. But the problem is the same.
There are many variables that go into radiative forcing. In their formula, they have claimed the only important variable is the no-reemission absorption a. They then fit their formula to the current temperature by choosing an “energy retention factor”.
But it is easy to fit a formula to a single data point (as I showed with the pirate example). That doesn’t make the formula correct. There is no reason to believe this energy return factor is not itself a complicated function of CO2 concentration, and the other GHG concentrations relative to it.
Last thing: it’s not too hard to calculate the radiative forcing correctly (see for example reference 9 in the paper). Since this paper disagrees with that one, I would think the more thorough calculation should take priority.
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Sam, there are many objections that are made against the IPCC supposition that GHGs cause a 33K increase in global mean temperature. Bear in mind Coe et al. inquery is very focused: If the 33K effect is true, what is the contribution of each GHG?
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In any case, the calculation in this paper just isn’t correct. It isn’t based on a rigorous physical derivation, as you would find, for example, in the Happer paper. Rather, it pulls a plausible sounding formula out of a hat and fits that formula to a single data point using a free parameter. But literally any formula can be fit to match a single data point, so this is no support for its validity.
The results in this paper strongly disagree with the more thorough calculation in Happer’s paper, which find (if I remember correctly) a sensitivity to doubling CO2 of around 1.2 C without accounting for any feedbacks, and 2.5 C with water vapor feedback. I am more inclined to trust the calculation based on rigorous physics, than this one which is essentially a curve fit to a single data point.
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OK Sam. Enough said.
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– “CH4 and N2O are indeed very powerful absorbers of infra-red radiation.”
No, they are not. Take a look at the image on the page below:
https://www.researchgate.net/post/Can_anyone_suggest_a_site_for_downloading_atmospheric_transmission_data_for_the_UK
Not only are those very WEAK absorbers of IR, but their strongest response is at wavelengths shorter than those emitted by the Earth (at 15C Earth emits only to 10um).
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Thank you, Ron, for bringing up arguments from the “other side” of the coin. Discussion is needed in all fronts of science.
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I have been fascinated by how many people talk about things they think they know, having never really examined the subject or their thoughts in any real effort, but keep going because they’re supported by other people who also don’t think for themselves. They never consider the motives of others, and they don’t look at their own motives. It’s quite amazing…, and troubling.
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A comment by Jordan Peterson:
“It struck me about the communist manifesto that it was akin to something Jung said about typical thinking, meaning the thinking of people who weren’t trained to think. He said that when the typical thinker has a thought, it appears to them like an object might appear in a room. The thought appears and then they just accept it.
They don’t go the second step which is to think about the thinking, and that’s the real essence of critical thinking. So that’s why you try to teach people in university to read a text and to think about it critically; not to destroy the utility of the text but to separate the wheat from the chaff.”
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I’ve shared this with others. The way I explained it is it’s like putting a gap between yourself and the idea or thought, for in that way, you see the thought is not you, but something to consider, for we know not where thoughts come from. Thoughts, as I explained, I believe, are not you. But we do have an understanding, something we’re born with, or shines in us if we’re allowing, and from that, we can view others and ideas from a point of view of understanding. Then, we can tell the difference between real and gobbledeegook (I sometimes use that term. Hah.).
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There is also the matter of clouds, which, while usually considered to be a positive feedback, may actually be negative. In other words, as water vapor in the atmosphere increases, so do clouds, which reflect the incoming solar radiation, especially over the oceans.
https://www.drroyspencer.com/research-articles/satellite-and-climate-model-evidence/
There is also a positive correlation between the density of low maritime clouds and galactic cosmic rays. More GCRs, more cooling. And the more active the sun, the fewer the GCRs. as they are deflected by the solar wind.
https://www.thegwpf.com/henrik-svensmark-cosmic-rays-and-clouds-anno-2016/
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Thanks kbks. There is way more information and data on clouds and climate, but it is suppressed because it undermines the alarmist narrative. Here some that I found:
More 2019 Evidence of Nature’s Sunscreen
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That’s interesting. I doubt they are able to bring much usable data for long term understanding, as yet, but all learning requires a beginning point, and often, interesting observations come forth. Fascinating.
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Hi All/Ron
I’m new to this site but finding it very engaging 🙂
It’s certainly interesting work and I hope will attract interest from the scientific community. I hope that other researchers in the area look at it and constructively criticise and reproduce the work. However, I feel it is not a convincing paper and does not deserve public or government attention at this stage:
1) When one theory/piece of evidence emerges that is contrary to the vast majority of research, it is probably flawed in some way. That doesn’t mean it shouldn’t receive attention, but until independently verified, should be treated as highly provisional.
2) While the paper was peer-reviewed, it is in a relatively new journal that doesn’t even yet have a published impact factor. Peer review is far from perfect, even if it is the best we have. I note that the paper was accepted only 9 days after receipt. This is almost unheard of.
3) The authors do not seem to have the expertise in the area to change our understanding of the field based on their career profiles.
4) The paper is mostly based on simulation/calculation. I’m a fan of simulation, but unless it’s verified against the hard data, there is little confidence that could be placed in it.
5) The authors express surprise that current models of temperature variation have such high uncertainty. I don’t think that is surprising at all given the complexities of the planet’s atmosphere. They then advertise their method as a way to simplify the estimation of temperature. Simplification can be good at times, but here it feels like a euphemism for missing out important details. This is evidence of poor understanding of the scientific method.
6) The language used at times implies lack of professionalism/scientific neutrality. Especially, in the concluding paragraph or so.
I might be able to accept one or two of these points, but collectively, they make me highly sceptical of the credibility of this paper. As I said, however, that does not preclude the work from further scrutiny and duplication by independent researchers, nor for it to be completely cast aside. But it is not yet convincing.
Cheers
Gary
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Gary, thanks for reading and appreciating, and for critically intelligent comments. Yes Coe et al. are outsiders to the IPCC consensus group of climate scientists, but they have expertise re the dataset they are analyzing. As you say, their findings contradict the majority narrative pushing for CO2 reduction policies. But they are not alone in their critique. The post includes several other sources dissenting for various reasons from the popular understanding of global warming/climate change. As well, there are many other dissenting qualified scientists upon whose work I have posted, providing synopses and links to peer-reviewed publications.
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Yes, it can be hard to marry popular understanding from actual science!
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Just so. For example
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Listened to a couple “real” scientists, one demonstrating warmings happen without any look at Co2. The science of climate is incredibly complex. I find it fascinating, but know, I’ll never fully understand it. If these “real” scientists see aspects they are still studying, how can a regular blogger….?
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Thanks for commenting dw. Having a sense of realism and humility about what is known and not known is a rare quality even among the scientists. John Christy has that, and would that were more. Here’s a quote from him:
On Climate Knowledge, Dr. John Christy
Climate science is a murky science. When dealing with temperature variations and trends, we do not have an instrument that tells us how much change is due to humans and how much to Mother Nature. Measuring the temperature change over long time periods is difficult enough, but we do not have a thermometer that says why these changes occur.
We cannot appeal to direct evidence for the cause of change, so we argue.
The real climate system is so massively complex we do not have the ability to test global-size theories in a laboratory. Without this ability, we tend to travel all sorts of other avenues to confirm what are essentially our unprovable views about climate. These avenues tend to comfort our souls because we crave certainty over ambiguity.
Without direct evidence and with poor model predictability, what other avenues are available to us? This is where things get messy because we are humans, and humans tend to select those avenues that confirm their biases. (It seems to me that the less direct evidence there is for a position, the more passion is applied and the more certainty is claimed.)
One avenue many folks tend to latch onto is the self-selected “authority.” Once selected, this “authority” does the thinking for them, not realizing that this “authority” doesn’t have any more direct evidence than they do.
Other avenues follow a different path: Without direct evidence, folks start with their core beliefs (be they political, social or religious) and extrapolate an answer to climate change from there. That’s scary.
http://www.centredaily.com/opinion/article42846180.html
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The hope is to encourage people to think beyond the media. On my site, I listed many scientists who share the complexities.
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