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How do we know more CO2 is causing warming?

What the science says...

Select a level... Basic Intermediate Advanced

An enhanced greenhouse effect from CO2 has been confirmed by multiple lines of empirical evidence.

Climate Myth...

Increasing CO2 has little to no effect

"While major green house gas H2O substantially warms the Earth, minor green house gases such as CO2 have little effect.... The 6-fold increase in hydrocarbon use since 1940 has had no noticeable effect on atmospheric temperature ... " (Environmental Effects of Increased Atmospheric Carbon Dioxide)


To make a statement like, "minor greenhouse gases such as CO2 have little effect", is to ignore 160 years of science history. So let's look at who figured out the heat-trapping properties of carbon dioxide and when.

Experiments involving various gas mixtures had demonstrated the heat-trapping properties of water vapour, CO2 and methane in the 1850s. But those effects were yet to be quantified - there were no meaningful numbers. It was to be another 40 years before that happened.

Swedish scientist Svante Arrhenius (1859-1927) was the person who crunched the numbers. The results were presented in a remarkable paper, "On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground", in 1896.

The many calculations in the 1896 paper include estimates of the amounts of CO2 increase or decrease required to drive the climate into a different state. One example used was the Hothouse climate of the Cenozoic, around 50 million years ago. Another was the glaciations of the last few hundred millennia.

To get a temperature rise of 8-9°C in the Arctic, Arrhenius calculated that CO2 levels would have to increase by 2.5 to 3 times 1890s levels. To lower the temperature 4–5°C to return to glacial conditions, he calculated a drop in CO2 was needed of 0.62-0.55 times 1890s levels.

We know CO2 levels in the 1890s from ice-core data. They were around 295 ppm. Let's do the sums. A reduction factor of 0.55 to 0.62 on 295 ppm gives 162.2-183.9 ppm. Modern ice-core measurements representing the past 800,000 years show that in glacial periods, CO2 levels fell to 170-180 ppm.

What we now know due to additional research since 1896 when Arrhenius worked on this, is that CO2 was an essential 'amplifying feedback'. That means changes triggered by long term, cyclic variations in Earth's orbit cause warming or cooling and CO2 release or entrapment in turn. Those changes in CO2 levels affected the strength of Earth's greenhouse effect. Changes in the strength of the greenhouse effect then completed the job of pushing conditions from interglacial to glacial - or vice-versa.

Arrhenius also made an important point regarding water vapour: "From observations made during balloon voyages, we know also that the distribution of the aqueous vapour may be very irregular, and different from the ideal mean distribution." This statement holds true today: water vapour is a greenhouse gas but because water exists in gas, liquid and solid forms in the atmosphere, it is continually cycling in and out of the air. It is distributed in a highly uneven fashion and is uncommon in the upper atmosphere. That's where it differs from CO2.

Once CO2 is up there, it's up there for a long time. As a consequence it has a pretty even distribution: 'well-mixed' is the term. As Arrhenius quantified all that time ago, once it's up there it constantly absorbs and re-radiates heat in all directions. That's why dumping 44 billion tons of it into our atmosphere in just one year (2019 - IPCC Sixth Assessment Report 2022) is a really bad idea.

Please use this form to provide feedback about this new "At a glance" section. Read a more technical version below or dig deeper via the tabs above!

Further details

Good scientific theories are said to have ‘predictive power’. In other words, armed only with a theory, we should be able to make predictions about a subject. If the theory’s any good, the predictions will come true.

Here’s an example: when the Periodic Table of the chemical elements was proposed in 1869, many elements were yet to be discovered. Using the theory behind the Periodic Table, the Russian chemist Dmitri Mendeleev was able to predict the properties of germanium, gallium and scandium prior to their discovery in 1886, 1875 and 1879 respectively. His predictions were found to be correct.

The effect on Earth's greenhouse effect of adding man-made CO2 is predicted in the theory of greenhouse gases. This theory was first proposed by Swedish scientist Svante Arrhenius in 1896, based on earlier work by Fourier, Foote and Tyndall. Many scientists have refined the theory since Arrhenius published his work in 1896. Nearly all have reached the same conclusion: if we increase the amount of greenhouse gases in the atmosphere, the Earth will warm up.

Where there is less agreement is with respect to the exact amount of warming. This issue is called 'climate sensitivity', the amount the temperatures will increase if CO2 is doubled from pre-industrial levels. Climate models have predicted the least temperature rise would be on average 1.65°C (2.97°F) , but upper estimates vary a lot, averaging 5.2°C (9.36°F). Current best estimates are for a rise of around 3°C (5.4°F), with a likely maximum of 4.5°C (8.1°F). A key reason for this range of outcomes is because of the large number of potential climate feedbacks and their variable interactions with one another. Put simply, some are much better understood than others.

What Goes Down…

The greenhouse effect works like this: Energy arrives from the sun in the form of visible light and ultraviolet radiation. The Earth then emits some of this energy as infrared radiation. Greenhouse gases in the atmosphere 'capture' some of this heat, then re-emit it in all directions - including back to the Earth's surface.

Through this process, CO2 and other greenhouse gases keep the Earth’s surface 33°Celsius (59.4°F) warmer than it would be without them. We have added 42% more CO2, and temperatures have gone up. There should be some evidence that links CO2 to the temperature rise.

So far, the average global temperature has gone up by more than 1 degrees C (1.9°F):

"According to an ongoing temperature analysis led by scientists at NASA’s Goddard Institute for Space Studies (GISS), the average global temperature on Earth has increased by at least 1.1° Celsius (1.9° Fahrenheit) since 1880. The majority of the warming has occurred since 1975, at a rate of roughly 0.15 to 0.20°C per decade."

The temperatures are going up, just like the theory predicted. But where’s the connection with CO2, or other greenhouse gases like methane, ozone or nitrous oxide?

The connection can be found in the spectrum of greenhouse radiation. Using high-resolution FTIR spectroscopy, we can measure the exact wavelengths of long-wave (infrared) radiation reaching the ground.

Greenhouse spectrum

Figure 1: Spectrum of the greenhouse radiation measured at the surface. Greenhouse effect from water vapour is filtered out, showing the contributions of other greenhouse gases (Evans 2006).

Sure enough, we can see that CO2 is adding considerable warming, along with ozone (O3) and methane (CH4). This is called surface radiative forcing, and the measurements are part of the empirical evidence that CO2 is causing the warming.

...Must Go Up

How long has CO2 been contributing to increased warming? According to NASA, “Two-thirds of the warming has occurred since 1975”. Is there a reliable way to identify CO2’s influence on temperatures over that period?

There is: we can measure the wavelengths of long-wave radiation leaving the Earth (upward radiation). Satellites have recorded the Earth's outgoing radiation. We can examine the spectrum of upward long-wave radiation in 1970 and 1997 to see if there are changes.

Change in outgoing radiation

Figure 2: Change in spectrum from 1970 to 1996 due to trace gases. 'Brightness temperature' indicates equivalent blackbody temperature (Harries et al. 2001).

This time, we see that during the period when temperatures increased the most, emissions of upward radiation have decreased through radiative trapping at exactly the same wavenumbers as they increased for downward radiation. The same greenhouse gases are identified: CO2, methane, ozone and so on.

The Empirical Evidence

As temperatures started to rise, scientists became more and more interested in the cause. Many theories were proposed. All save one have fallen by the wayside, discarded for lack of evidence. One theory alone has stood the test of time, strengthened by experiments.

We have known CO2 absorbs and re-emits longwave radiation, since the days of Foote, Tyndall and Arrhenius in the 19th Century. The theory of greenhouse gases predicts that if we increase the proportion of greenhouse gases, more warming will occur.

Scientists have measured the influence of CO2 on both incoming solar energy and outgoing long-wave radiation. Less longwave radiation is escaping to space at the specific wavelengths of greenhouse gases. Increased longwave radiation is measured at the surface of the Earth at the same wavelengths.

Last updated on 16 July 2023 by John Mason. View Archives

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Further reading

A good summation of the physics of radiative forcing can be found in V. Ramanathan's Trace-Gas Greenhouse Effect and Global Warming.

Denial101x video


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Comments 376 to 400 out of 451:

  1. @JohnSeers @375

    Okay, I'll bite you back.

    1.  If CO2 isn't driving the initial temperaturte rise, then what reason is there to cite it in subsequent rises?

    2.  Did you forget about the ice core data?  Temperature goes up, then temperature goes down before yhe CO2 does.  Were you not paying attention?

    3.  Go ahead, do some.

    4.  Do you normally contradict yourself?  Decreasing surface wind speeds is associated with increasing surface temperatures.  Decreasing global surface wind speeds means what, no global surface temperature change?

    Do pay attention.


    [DB]  This is a moderated forum.  Please comport your comments to comply with this site's Comments Policy.  

    From the depths of the Last Glacial Maximum 20,000 years ago, CO2 levels increased due to warming from Milankovitch forcings, which then triggered an immense increase in atmospheric CO2, which drove the bulk of the temperature increase needed to drive the world from full glacial phase into the full interglacial world of today.

    In short, the initial warming was indeed triggered by the Milankovitch cycles, and that small amount of orbital cycle-caused warming triggered the CO2 release from the Southern Oceans, which caused most of the glacial-interglacial warming.  CO2 led and was the primary driver behind most of the glacial-interglacial warming.

    From Parrenin et al, we see that temperatures and CO2 levels in Antarctica rose synchronously, with no lag in either measurement.

    According to the Shakun et al data, we see that increase in atmospheric CO2 led the increase in global temperatures for the remainder of the globe.

    Shakun 2012

    Inflammatory rhetoric snipped.

  2. Youjaes @376 , LOL but please do not bite me   ;-)

    1.    . . . was expressed rather ambiguously.   For each rise (or fall) of temperature in glaciation/de-glaciation, the first 10% is caused by slight variation in "insolation" and the subsequent 90% is caused by change in CO2 level (i.e. change in GreenHouse Effect).   Rough figures, of course.

    So your comment #1 was 90% wrong.  Ah, if only you had read the Original Post and subsequent comments!    ;-)

    2.  Ice core data conforms with the 10% / 90% description (above). 

    No problemo !

    3.  The so-called (but poorly-named) GreenHouse Effect [ = GHE ] has already been shown with data from satellites.   Long ago.   ( But half the crazies at WhatsUpWithThat blog . . . are still in full denial about it all !  . . . even though the good Mr Watts occasionally whispers that they're wrong to deny it. )

    No need for backyards or front yards being involved.

    4.   As global warming has proceeded, wind speeds have slowed very slightly, I am told.   But WUWT has made a mountain out of a molehill, on that.   Kind of a nothingburger.   Strange, since WUWT is usually trying to make molehills out of mountains !    ;-)     ;-)     ;-)

  3. "1. If CO2 isn't driving the initial temperaturte rise, then what reason is there to cite it in subsequent rises?"

    Ah... because that's the difference between a forcing and a feedback.

    Without that CO2 feedback the initial orbital forcing would only produce a very small change in temperature. The resulting feedback is what gives us glacial/interglacial cycles.

    Regardless, the effect is the same. CO2 is a gas with radiative properties. Adding CO2 to the atmosphere will cause the planet to warm. Add lots of CO2 and the planet will warm a lot.

  4. I am not a scientist but would somebody explain to me how a gas that consists of 400 parts per million is going to heat the other 9600 parts per million in any significant way and why would one of the other green house gases water vapor not have a much greater effect.  

  5. Firstly let me say how much I have enjoyed reading this topic, oh and I had better add I have no doubt that mans activity is warming the planet, but I am a little at odds with the how....

    I must confess that I am more than a little surprised that in everything I have read there is no mention of the heat component thats mans activity is adding to global warming?

    I we take the ocean for instance a throw a few thousand ships in it pouring billions of Kw of heat in to the ocean for say the last 70 odd years, and more than 1 or 2 reactors in subs spewing heat in to the oceans.  The ocean is not infinite, so all of this hot water must go somewhere, right?.  Where are the calculations that determine what percent of the oceans warming is by the heat released by mans "industry"?

    And again if we take the worlds population and distribute it evenly over the globe for the sake of back of the napkin math, tabulate the daily fuel burn, heat released by reactors, exothermic process in industry, heat released by electrical appliances driven by wind and hydro, (some fair guesses can be made here) and apply it to our 1 square km model.  Throw a bit more water vapor in to the atmosphere, as after we are burning fossile fuels, stand a coloum of air on the top of this heat source about the dimensions of the atmosphere with a large heatsink at the other end and you come up with some really interesting numbers.  Certainly they are big enough to be, well not nothing.....

    My back of the napkin math suggests that the heat being produced by mans industry at the very least needs to be incorporated in to any greenhouse model, and the sun is not the only significant source of heat.  I suspect that greenhouse gases are not nearly as efficient at trapping heat as we give them credit for and the petawatts of heat being liberated in to the atmosphere by man are a much bigger part of the "full" picture, especially when the wavelength of wate heat is considered....

    Is it just me or has this work been done already?  Or am I simply wrong?


    [PS] Please see the "its waste heat" myth and post any further comments on that thread please, not here.

  6. Dukester @380,

    My back of fag packet calculation puts the energy used by shipping at roughly (300Mt/year x 43 GJ/t / (8766 x 3600) = 400 GW. That is certainly billions of kWh/year. But as a global forcing it comes to 400e9W / 510e14m = 0.0008Wm^-2. As of last year NOAA AGGI puts the forcing from CO2 at 2.044Wm^-2 with a total positive GHG forcing of 3.1Wm^-2. Burning fossil fuels does result in much energy release but, depending on the fuel, the resulting increase in atmospheric CO2 will be heating the planet by the same amount over the following 9 to 18 months, and again for following periods of that length. The combustion energy release thus quickly becomes a trivial value relative to the GHG forcing.


    [PS] no more comments about this on this thread please. Take it to the waste heat thread.

  7. Recently many scientist start to doubt on such theories about man made climate changes, specially those from other background like me. I am a phisicist. For me it is difficult to give credit to a mere conference paper as the one you cite as main reference. Is there any other reference to address the full sun spectrum and compare with the presented one? Also I am in doubt of the name you used to describe the FTIR spectrum. It is not a " greenhouse radiation spectrum" as you claim, it is just an FTIR of the atmosphere. Have the authors accounted for the emissions from the Earth and subtracted them? You can use a simple fit with a black body radiation with an emissivity also called as brown body. Another issue is the water spectrum being ommited. Why? Is not the water contributing to warm Earth's surface? In resume I do believe in the possibility of warming, my main criticism is that experimental procedure seems to be incorrect. Also to a cientist it is not enough saying that many people believe in something or that you're the majority of them. This is not the way scientific evidence is validated. If there is ANY inconsistency in ANY theory it does not turn it completely false immediately but it put the model in serious doubt. Number of scientist that agree to a flaw evidence is useless here. I rather know how do you conduct your research and how do you reach your conclusion. So tell me some measurements made from a standard labs like the NREL of the sun radiation. Because to compare data taken from distinct instruments one decades after the other in distinct times of the year or even the day and also without absolute power calibration cannot be accounted as serious science. Forgive me by being skeptical but that is my job and I am giving you an opportunity to show me more arguments of your claim.
  8. Rero @382 ,

    What a happy co-incidence that you have posted here!  I am delighted to find another fellow phisicist.  There are so very few of us, and our scientific field of specialty is so very new, that it has not yet even been incorporated into the Oxford English Dictionary (but I have hopes it will be so, in February).

    More to the point, Rero, you have unfortunately been extremely vague in your commentary ~ amounting to little more than semantic nihilism.

    Best if you start from the beginning, and provide some names of well-qualified & well-informed scientists who have recently (say in the last 100 years) developed a credible doubt about the mainstream physics of climate.

    More importantly, you should specify the plausible (and preferably peer-reviewed) evidence which justifies their doubt.  Because we phisicists abhor empty words, do we not?

  9. Eclectic @383,

    I fear you fail to spot the linguistic limitations within the comment of Rero @382 who doesn't sound like a native English speaker. And I do not see Rero @382 saying there are "well-qualified & well-informed scientists who have recently developed a credible doubt about the mainstream physics of climate." Rather it is "recently many scientist start to doubt" (my bold). There is no mention of "credible doubt."

  10. Rero @382,

    Picking up on some of your comment, I would echo the view @383 that if you do mention their existence you should give some indication of who these 'recently doubting scientists' are.

    You also mention the figure in the OP of Spectrum of Greenhouse Radiation described in the OP as measurement of FTIR spectroscopy. This is clarified in the paper referenced which states "The measurements have been obtained using commercial Fourier-transform infrared (FTIR) spectrometers." You ask for a more substantial reference than Evans & Puckrin (2006) 'Measurements of the Radiative Surface Forcing of Climate' which is a conference paper. The figure is not controversial so I am not sure why further reference is required. The same result can be obtained using the UoC MODTRAN model (with Water Vapor set to zero, altitude to zero and looking up). But if you insist on a peer-reviewed published paper, perhaps Ellingson & Warren (1996) would be what you are looking for.

    Your following statements are not entirely clear. When you state "my main criticism is that experimental procedure seems to be incorrect," this seems to be separate from the criticism of using consensus to define the science (which is not a valid crticism. The consensus rests on science, not the other way round). If your "main criticism is that experimental procedure seems to be incorrect" and if this is separate from your consensus consideration, please set on why you consider the "experimental procedure seems to be incorrect".

  11. MAR @384 , your comment is doubtless kindly meant.  There were numerous indications (including the first sentence of #382) that it was a case of "non-native English".   And no-one should object to grammatical and spelling trespasses, where the underlying meaning is obvious enough.   Just as each of us would hope to be forgiven our own trespasses.   (And I am very happy for posters to post comments in their native tongue . . . although often it would be prudent for them to provide a rough translation into English, for the benefit of the majority readership.)

    Nevertheless, to borrow a non-English word, there was in #382 a considerable chutzpah  in making an improper spelling of physicist , while criticizing/berating the mainstream scientists for inattention to proper detail.   The irony was amusing.

    MAR, you have a formidable depth of knowledge of climate matters, and I find it hard to believe that you could find it credible that Rero would come up with anything to back up his statement that "many scientists were starting to doubt".   That's why I asked Rero to name some scientists & supply a modicum of the evidence on which any true scientist could base his "increasing doubt".   Of course, a real scientist is only wishing to entertain credible doubt [my phrasing, not Rero's].

  12. Figure 2 is wrong. This was pointed out more than 10 years ago @1 by HumanityRules. The caption for Figure 2 says "Change in spectrum from 1970 to 1996...", but Figure 2 is a copy of the Harries 2001 1c graph, a simulated spectrum, i.e. a purely theoretical graph, something never measured at all, which is why all the values are below zero Kelvin. This article should be using a copy of the Harries 1b graph instead: the actual measured spectrum difference between 1970 (IMG satellite) and 1996 (IRIS satellite). In the the 1b graph there are large portions above the zero line, e.g. between 750 - 1100. This is what @HumanityRules was asking about: why so much positive energy at these frequencies? @2 provides an explanation from the Harries paper itself about "residual small ice crystal effects". However, I believe this explanation is wrong. The real reason for a <b>net positive</b> energy difference between 1996 and 1970 is that the earth was warmer in 1996 than it was in 1970. The Stefan Boltzman law requires that a hotter earth emits more heat. Since CO2 and CH4 and other trace GHGs are blocking parts of the emitted IR spectrum, then other parts of the spectrum must make up for this. The Harries 1b graph simply confirms that earth was warmer in 1996. In contrast, Figure 2 implies that the earth was cooler in 1996 than in 1970.

  13. If greenhouse gases such as CO2 are absorbing the sun's radiation and emitting it as long wave infrared radiation as the post suggests, why would an increase in atmospheric CO2 translate to an increase in downward longwave emissions but a decrease in upwards longwave emissions attributed to CO2 as measured via Satelite? Again, as the post suggests, greenhouse gases absorb the sun's radiation and then these same gases emit that radiation in all directions (not favoring up or down). Wouldnt an increase in atmospheric CO2 (and O3, CH4) result in an increase in both upward and downward longwave emissions for their respective greenhouse gases? 

  14. unsure @388,

    The essential characteristic of GHGs is that they do not absorb sunlight. They do absorb (and re-emit) the long wave infrared. With an increase in CO2, there isn't directly an increase in the 'intensity' of this long wave infrared, be that up, down or sideways. That is, there are more CO2 molecules emitting, but there are also more CO2 molecules absorbing. The extra absorption means the higher number of emitted infrared photons have a reduced pathlength. So at any point, the surface say, the infrared recieved is unchanged by simply adding CO2. Something else has to happen to increase the infrared 'intensity'.

    What does cause this increase in infrared (up, down and sideways) is an increase in global temperature. The temperature rises because the extra CO2 increases the height in the atmosphere at which the CO2-emitted infrared has a clear shot at space. This means the CO2 molecules shooting out to space are in a higher colder part of the atmosphere. Cold gases emit less than warm gases, so to balance the global energy equation the planet has to warm, thus boosting the infrared emissions into space, from all sources, not just CO2. Note that because the temperature boost to infrared is across all sources and this is to balance the reduced infrared from CO2 alone, there will still be less CO2 emissions out into space when the balance is restored.

  15. Unsure @388 , I will add in some extra food for thought.

    The "greenhouse" planet-warming effect of the GHG [GreenHouse Gasses] molecules is not simply explained in a single sentence (or three).  But once you get your head around how it works, you will see that it is a straightforward basic mechanism.

    You will need to do some more of reading & thinking it through.  Several points to keep in mind :-

    (A)  InfraRed photons are emitted in all directions by the CO2 molecules ~ when each molecule has enough energy to emit an IR photon.  Emission rate depends on local air temperature.

    (B)  The energy (to produce an IR photon) for each CO2 molecule ~ is gained from collision with neighbouring "air" molecules (almost all of which are nitrogen and oxygen).   Likewise, when a CO2 molecule receives/gains an IR-photon's worth of energy, the CO2 molecule immediately distributes energy to neighbouring "air" molecules, by collision.   In other words, a CO2 molecule can warm the neighbouring nitrogens/oxygens when it receives an IR photon . . . or it can (by emitting an IR photon) cool its neighbouring nitrogens/oxygens.

    (C)  Each layer of air is receiving and radiating IR  from/to the layers above and below . . . except for the uppermost layer, where the CO2 is so "thin" that some of the radiated IR photons can escape to outer space, through the "gaps" between the nearby CO2 molecules.   (Lower layers with denser concentrations of CO2, in effect have "no gaps".)

    (D)  All of the above, also applies to IR emission/absorption by other GHG's e.g. methane, water vapor ~ but for each of these other compounds, the corresponding "uppermost thin layer" is at a different altitude (than CO2's "Top Of Atmosphere" emitting layer).   O3 is rather a special case, being mostly in the stratosphere.

    And I will stop at that point, since the consequence of all this is the higher heat concentration at the planet's surface i.e. the so-called (and poorly named) GreenHouse Effect.

  16. I have found Chris Colose's explanation very useful, particularly the last diagram on effective height.

  17. Ok. I am new to this thread. I wonder if someone could help me with a CO2 concentration problem? I was researching CO2 levels on other planets to compare those to Earth along with surface temperature and atmospheric pressure so I can understand how they all interact. The CO2 concentration on Earth is .041%; the average temperature is 59F; and the atmospheric pressure is 14.7psi. Lets go to Venus now: CO2-96.5%;average temp+864F; atmosperic pressure-1363psi. And lastly Mars:CO2-95%;Temp- -81F; atmospheric pressure-.088psi. Can someone explain how Mars and Venus have basically the exact CO2 concentrations that are magnitudes above ours; and have drastically different temperatures?  Thanks if anyone can explain this to me.

  18. Responding to the question posed @392 (not being sure if the commenter is still 'with us', but the question remains),

    The point of a greenhouse effect is that it elevates the temperature of the planet above the temperature it would be without a greenhouse effect. Thus (and apologies for using SI units here) the start point is the actual surface temperature of the different planets minus their blackbody temperature. And it is not the percentage of CO2 but the volume of CO2 that should be considered because 100% of naff-all is still naff-all.

    (Note this is an overly simplistic analysis as a greenhouse effect can be reliant-on or boosted-by the presence of other gases. For instance, on Earth the greenhouse effect would be 25% of current values if the CO2 warming wasn't boosted mainly by water vapour and clouds for the remainder. And it is not just greenhouse gases that can play a role.)

    From this Venus fact sheet & this Mars fact sheet:-

                                              Venus         Mars          Earth

    Surface teperature                737K        210K         288K

    Blackbody temperature         226K        210K         254K

    Greenhouse effect                 515K            0K          33K

    Atmospheric pressure             92bar  0.006bar       1bar

    CO2 (by weight)                      96%         96%        0.06%

    CO2 content                           88bar   0.006bar    0.0006bar

    So the answer to the question "how Mars and Venus have basically the exact CO2 concentrations that are magnitudes above ours; and have drastically different temperatures?" is that the strength of the greenhouse effect is reliant (simplistically) on CO2 content and not CO2 concentrations. The table presented here simplistically sets out why Mars and Venus have "drastically different temperatures". The Mars/Earth difference is another (and more complex) story.


    [DB] The user account to which you were responding is a sock puppet account of the same name as the user which ceded their commenting privileges previously.  This new iteration of the account had its commenting privileges accordingly suspended.  As will all future iterations.

  19. (Checking to see if my post uploads successfully to SkS)

    Thank you, MA Rodger.   Mr Dakota was quite off-target in trying to picture things in relative CO2 concentrations such as 0.041% or 410 parts per million.

    As you say, the presence of water vapor adds a large complication ~ except for Mars.   Adjustments also for albedo or reflectiveness at non-visual wavelengths . . . plus or minus reflectiveness of sulfate aerosols from industrial and/or volcanic origin.   Other adjustments for Earth's tilt or seasons, and for clouds at different heights & latitudes.

    The climate scientists certainly have their work cut out for them, to get a handle on it all.   Mr Dakota is probably tempted to think it's much easier just to be a science-denier, and firmly close one's eyes to reality !

  20. Correlation does not confirm a theory, it leads to a mechanism . There is not enough CO2 in the atmos to account for global sea temperature rise. Temperature rise is caused by the tremendous Heat emanating from Coastal cities. This Heat goes into water ( sewers, streams, sheet water) into rivers into the Sea. Civilization cause water sources to become Turbid, there is not enough water treatment to prevent Turbidity levels. Heat and Turbidity cause anoxic regions to proliferate. Warm coastal water causes storms and polar melting of ice. Civilization itself causes Global warming not levels of Carbon dioxide.

  21. pettman - Waste heat is _not_ the problem; the forcing changes from waste heat in our climate system are 100x smaller than the CO2 forcing. See Greenhouse warming 100 times greater than waste heat, where you can check the numbers. 

    The data does not support your assertion. 

  22. Pettman says "Correlation does not confirm a theory, it leads to a mechanism." You got this exactly wrong. The mechanism is identified by physics and does not depend at all on the correlation. Correlation is in fact more important when there is not a known physical process, hence the vacuity of the null hypothesis problem advanced by some so-called skpetics. Furthermore, the correlation does not lead to a mechanism, it only shows the possible existence of causation, which then must be identified separately. Then the mechanism of why something causes something else should be investigated. That is, of course, in cases where only statistical data is available initially to investigate a phenomenon. Fortunately, in the case of climate change, the correlation was predicted beforehand by physics, and its later appearance in the data was an expectation.

  23. @pettman @395

    Some interesting ideas there. You have obviously done considerable research to come up with those thoughts. Could you please give some of the key references that you have used to come to your conclusions. They would make very interesting reading. 

  24. What is this? It appears to pop up on the denier blogs these days.

  25. SDK @399,

    You provide the link to Allmendinger (2017) 'The Refutation of the Climate Greenhouse Theory and a Proposal for a Hopeful Alternative' and say it is featuring on denialst sites. This should not be a great surprise as Allmendinger (2017) is a pack of nonsense, pretty-much like the rest of the content of denialist websites. There is a post about this particular pack of nonsense at …and Then There's Physics. Apparently Allmendinger paid $519 for his vanity publication.

    Another grand work from the same author was 'published' a few months later, 'The Real Cause of Global Warming and its Implications', and a further work with a similar title is also listed in his biog but appears to have disappeared with a defunked website. Other works are listed here. I would suggest the only reason for examining them would be to gain a better insight into the mind of a lunatic obsessive.

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