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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)

Predicting the Future

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 Table of Elements was proposed, 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, despite the fact they hadn’t been discovered.

The 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 and Tyndall. Many scientist have refined the theory in the last century. Nearly all have reached the same conclusion: if we increase the amount of greenhouse gases in the atmosphere, the Earth will warm up.

What they don’t agree on is by how much. 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).

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 about 0.8 degrees C (1.4°F):

"According to an ongoing temperature analysis conducted by scientists at NASA’s Goddard Institute for Space Studies (GISS)…the average global temperature on Earth has increased by about 0.8°Celsius (1.4°Fahrenheit) since 1880. Two-thirds of the warming has occurred since 1975, at a rate of roughly 0.15-0.20°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.

 

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 outbound radiation. We can examine the spectrum of upward long-wave radiation in 1970 and 1997 to see if there are changes.

 

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

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 know CO2 absorbs and re-emits longwave radiation (Tyndall). The theory of greenhouse gases predicts that if we increase the proportion of greenhouse gases, more warming will occur (Arrhenius).

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.

These data provide empirical evidence for the predicted effect of CO2.

Basic rebuttal written by GPWayne

Last updated on 1 August 2013 by gpwayne. View Archives

Printable Version  |  Offline PDF Version  |  Link to this page

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.

Comments

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Comments 101 to 143 out of 143:

  1. Aye, agreed.
  2. (-Snip-)
    Response:

    [DB] Again, you must finish up what you initiated on the It's the sun thread before you can initiate something on another.  What you are doing is trolling.  If you persist in this behaviour your posting privileges will be reconsidered.

  3. DB, we are not responding to Mace on the "It's the sun" thread because he has still not properly responded on The 2011 Climate B.S.* of the Year Awards thread.
    Response:

    [DB] Thank you for your guidance, and your efforts.  Mace has found compliance with the SkS Comments Policy too onerous & has recused himself from further participation.

  4. http://www.engineeringtoolbox.com/spesif...d_159.html

    Gas or Vapor kJ/kg

    Air 0.287

    Carbon dioxide 0.189

    Water Vapor 0.462
    Steam 1 psia.
    120 – 600 oF

    That’s what it takes to change the temperature 1 degree K.

    When CO2 changes from 1 to -1 C, a change of 2 degrees C, it radiates 2(0.189 kJ/kg) = 0.378 .

    http://en.wikipedia.org/wiki/Enthalpy_of_vaporization

    When water vapor changes from 1 to -1 (and condenses) it radiates 2257 kj/kg + 2(0.462 kJ/kg) = 2257.853776 kJ/kg.

    It does this every single time you see a cloud.
    But CO2 has no phase change so it carries no heat – the numbers:

    All gases at the same temperature have the same number of molecules per unit volume. (Avogadro)

    Water, being light, masses 18g/mole and CO2 masses 44 g/mole

    Using 1 mole of air, just to make math easy:

    We lowball the water in the atmosphere at 1% of the molecules

    So, in a mole of atmosphere, we have 0.01 moles of water = 0.18g

    now we highball the CO2 at 500ppm which is 0.0005, or 1/2000 of a mole of CO2.

    1/2000 * 44g/mole = 0.000484 moles of CO2 = 0.021296g

    So in our mole of air with but 1% H2O and a generous 500ppm CO2-

    the water condensing radiates 0.18g * 2257.853776 kJ/kg = 406.41367968 J

    while the CO2 radiates 0.021296g * 0.378 kJ/kg = 0.008049888 J

    the ratio of 0.008049888/406.41367968 = .00001980712855516645290496438242332

    or as much to say that water vapor in the example carries 50486.873814890343815963650674393 times more heat than the CO2 does.
    And that’s just rain. If it turns to snow- multiply by 5-6.

    Meanwhile, Venus is a ball of active volcanoes with a dry heat pump to radiate it poorly.

    That is why Earth’s climate doesn’t resemble that of Venus.
    Forget about CO2.
    Response: [JH] "Dana69" is not an SkS author.
  5. Dana69 @104, I'll grant you that it is a novel approach. To bad that you make such fundamental errors. The most important error is that there is no requirement that the heat be radiated away. In fact, most of the heat will be carried away by collisions with other molecules. Therefore your assumption that be comparing the heat content of molecules you can determine the relative contribution to the Outgoing Long wave Radiation, and hence the overall temperature of the Earth is a simple non sequitur.

    In fact, the radiation of IR radiation by each gas is a direct function of it temperature, emissivity and concentration, and nothing else. The heat capacity determines how long it takes for the gas to heat, or cool given a particular flow of heat. Indirectly it helps determine the lapse rate in the troposphere. But beyond those two factors is has no further bearing on the greenhouse effect.

    Finally, those so equipped can easily determine the absurdity of Dana69's suggestion. The need merely direct an IR camera at a cup of water as it is first heated then cooled. They will find that as it warms (and hence is absorbing more energy than it give of) it radiates more, whereas when it cools (and hence is giving of more energy than it absorbs) it radiates less. If you compare the IR flux measured using the camera, you will find the same flux for a given temperature regardless of whether it is warming or cooling.
  6. But, Tom, what Dana69 says looks interesting. It's got numbers, and calculations, and references to laws. And it has an attempt to stop dialogue at the end of it--the hallmark of a good faux skeptic.
  7. And aren't Venus' volcanoes all but extinct? No more plate tectonics?
  8. Rob the volcanoes found on Venus are not of the type associated with plate movements. The front running theory on the planet's geology is that of periodic volcanic resurfacing, no plate tectonics. Although no active volcano has been observed, evidence of volcanic activity is everywhere to be seen on the surface.
  9. Any increase in backradiation’s contribution to warming would still be subject to the defect of GMST; that is (A + B)^4 > A^4 + B^4 which shows that backradiation, like all Stefan-Boltzman effects, is subject to regionalised variation which defeats any averaging that AGW relies on as a metric.
    Response: [JH] "Dana69" is not an SkS author.
  10. Dana69 - Variations in surface temperature will increase the energy radiated, and Trenberth 2009 discusses that. Their estimates of 396 W/m^2 are an increase from the 390 W/m^2 stated in the earlier version of the paper for that very reason.

    "...regionalised variation which defeats any averaging..." - This is an issue recognized by folks in the field, where temperature variations are taken into consideration. Certainly not a "gotcha" moment, wherein it turns out that all of the science is wrong due to an overlooked variable...

    As I recall, you were involved in a discussion of CO2 and radiation over at the CO2 is just a trace gas thread. You demonstrated some understanding of the issues there, which makes your current comments puzzling.
  11. KR,

    They are perhaps puzzling since both #109 and #104 are copied and pasted from comments on science of doom.

    #109 is posted under user cohenite
    while
    #104 is posted under Dave McK, appearing again at WUWT
  12. IanC - That's absolutely fascinating...


    Dana69 - Perhaps you could either offer your own opinion, or clearly link and credit to issues you feel important, rather than plagiarizing other folks words? I'm getting the distinct impression of a troll, rather than someone who holds their own views on the subject.
  13. Fascinating stuff, IanC. So either Dana69 is cohenite (aka Anthony Cox), or Dana69 is an intentional plagiarist. If Dana69 = Cox, your puzzlement, KR, is resolved. Cox has a vested interest in maintaining a specific position re climate. Until he can demonstrate an ability to accept his own error (learn), his posts can be considered nothing but trolling. If Dana69 is not Cox and is a plagiarist, then Dana69's ability to express his/her actual understanding is suspect, and further dialogue is probably (but not certainly) a waste of time (since one never knows who one is actually engaging in dialogue with -- a pastiche or the original brain).

    All of this is obvious, but it's worth pointing out to anyone tempted to respond to Dana69 (until such a time as Dana69 addresses the issue, of course).
  14. DSL - Given that Dana69 has copied posts from two different authors (assuming that cohenite doesn't also post as Dave McK), I would suspect that it's not cohenite under another handle.

    DNFTT
  15. Dana69 @109 appears to not recognize that climate predictions are made with climate models that use (relatively) high resolution grids of the surface. The GISS-HYCOM model, for example, uses a 4 degree latitude by 5 degree longitude grid, thereby dividing the Earth's surface into 3240 cells. The model has 20 layers for the atmosphere, meaning the atmospheric model divides the atmospheric model divides the atmosphere into 64,800 cells in total. Oddly enough, the model does not constrain all cells to maintain the same temperature, a necessary constraint for Dana69's comment to have any relevance.

    GISS also runs a 2 x 2.5 degree model, which therefore has 12,960 surface cells, if that is not enough resolution for you. Dana69 may feel that dividing the Earth into 12,690 cells does not sufficiently account for regionalization, but that tells us more about Dana69 than climate science.

    When will the fake skeptics wake up to the fact that pretending climate science is based on a single zero dimensional model, as Dana69 has done, reveal them to be cranks pushing an agenda in no uncertain terms?
  16. And of course whoever originally wrote post #104, that was plagiarised by dana69, also neglected to discuss evaporation: whereupon liquid water absorbs all that extra energy to become the water vapour that is able to release energy. I presume they just forgot...
  17. skywatcher @116, are you suggesting that averaged over time, just as much water falls to the ground as raine (or snow etc) as evaporates. What sort of radical new theory is that. (/sarc)
  18. Tom #117, Apparently, according to #104, all the water you and I naively feel as rain, actually is dropped off by passing comets, the water having never evaporated from the ground. This also accounds for sea level rise and so there is nothing to worry about. /sarc
  19. "A good summation of the physics of radiative forcing can be found in V. Ramanathan's Trace-Gas Greenhouse Effect and Global Warming."

    Is a broken link.
    Response:

    [DB] Fixed link, thanks. The actual URL is: http://www-ramanathan.ucsd.edu/files/pr72.pdf

    A portion of V Ramanathan's publication list can be found here.

  20. From the introductory paragraph, surely this is incorrect:

    "The Earth receives energy from the Sun in the form of visible light and ultraviolet radiation, which is then re-radiated away from the surface as thermal radiation in infrared wavelengths."

    About half of the energy in sunlight is near and short wave IR, and surely it is mostly this component of sunlight which heats the planet and is rebroadcast as longwave IR.
  21. Ruffy, can you give a reference to a reputable scientific source for the claim of half of the energy in sunlight being near and short wave IR?
  22. Dikran Marsupial, I know it's not a science paper but Wikipedia puts the sun's input to the planet at about 1 kilowatt per square meter of which "527 watts is infrared radiation, 445 watts is visible light, and 32 watts is ultraviolet radiation". There is also a graph showing the ultraviolet, visible and infrared boundaries linked to the "Sunlight" page.

    The source looks credible and contains a spreadsheet of the wattage values for each wavelength.

    Significan energy in wavelengths longer than 0.74µm is also shown in the blackbody emission graph of the sun and earth on the Science Of Doom's excellent page on back radiation.
  23. Ruffy wrote: "About half of the energy in sunlight is near and short wave IR, and surely it is mostly this component of sunlight which heats the planet and is rebroadcast as longwave IR."

    So what do you imagine happens to the energy from visible light? Does it magically cease to exist or 'go away' somewhere? If so, why is it that white objects (which look white precisely because they reflect most visible light) do not heat up as much as black objects (which absorb most visible light)? Why does electromagnetic radiation in the range that we have arbitrarily labelled 'infrared' behave differently than that in the range we can see?
  24. @Sapient fridge, many thanks, Wikipedia is fine for me (where it has external references), at least as a start. I think the thing that Ruffy might be missing is that a lot of that radiation will be absorbed by the GHGs in the atmosphere before it gets to the surface (which will only see the IR that is not in the absorption bands of H2O, CO2 etc.). I suspect most of this gets re-radiated back out into space (at each "layer" in the atmosphere half is re-radiated up and half re-radiated downwards, so the amount heading downwards decreases logarithmically?). That would be my intuition anyway.

    The point still remains however, as CBDunkerson mentions, that increasing CO2 will still increase warming at the surface by absorbing the IR re-radiated from the ground from incoming visible, UV and unabsorbed IR (which will be re-radiated at wavelengths included those that are absorbed by GHGs).
  25. Ruffy @120, to put this into perspective here is a graph of the energy content of solar radiation to the Earth by wavelength, along with important absorption bands:



    As you can see, the 49% figure is about right. However, very little of that 49% is in the wavelengths of the outgoing radiation, as can be seen by this diagram:



    You will note that nearly all of the incoming solar radiation is absorbed by water vapour, or by the surface. As nearly all the water vapour in the atmosphere is in the bottom four km of the atmosphere, that means nearly all of the energy is absorbed at, or near the surface. Therefore I must disagree with Dikran Marsupial @124, not because his analysis is wrong, but because his assumption that the incoming energy is at frequencies where there is significant absorption by well mixed greenhouse gases (ie, GHG other than water vapour and ozone) is false.

    It should be noted that the energy absorbed by water vapour near the surface from the sun is very small compared to the energy absorbed from the surface. Based on the energy balance by Fasulo and Trenberth, the near surface atmosphere absorbs around 450 W/m^2, compared to around 80 W/m^2 absorbed in the atmosphere (as significant proportion of which is UV radiation absorbed by the ozone layer). Given this, and given that convection ensures a well structured temperature profile in the lower atmosphere, the energy absorbed in the lower atmosphere can be treated as being absorbed at the surface for nearly all practical purposes.

    That being the case, the IR radiation from the sun does not differ significantly in its effects from the visible light from the sun. It is absorbed at the surface. It is not directly reradiated but rather, redistributed as heat through the collisions of molecules, some of which then emit IR radiation at an entirely different wavelength, that radiation constituting the Earth's thermal radiation.

    And, of course, to maintain an energy balance, the energy received by the Earth must equal the energy which leaves the Earth. If the Earth's IR radiation came only from the IR radiation received from the Sun, then about 50% of the Sun's energy would not be reradiated back to space. The resulting energy imbalance would be a catastrophe worse than a full nuclear exchange, even if maintained for a single day.

    So, yes the Earth does receive IR radation from the sun, primarily at wavelengths where it is absorbed at or very near to the surface; but no it is not this component alone (or primarily) that results in the Earth's IR radiation from the surface or to space.
  26. @Tom, many thanks for correcting my intuition, getting things wrong and having ones understanding challenged is an excellent way to learn! Forgetting that the water vapour is in the lower trophosphere should have been obvious even to me. ;o)
  27. Hello, I'm new to this place and don't really want to cause any fuss and this may have been covered elsewhere, however I am very interested in all of the topics covered so far. Not wanting to post a link to anything that may be biased whatever a persons personal belief is, I still believe scientific work deserves credit where it is due and discredit if it can be falsified. Please any input on the findings of Roy. Clark on the questioning of radiative forcing models and techniques would be much appreciated.

    http://venturaphotonics.com/GlobalWarming.html

    I realize he is very much what you would consider a skeptic but any confirmation of his observations and/or conclusions, contradictions, corrections would be handy. I am currently unaware if he has tried to submit this work for peer review as I doubt he believes the system is currently without faults or bias itself. Thanks
  28. As a newcomer, Welcome!

    Quite frankly, anyone who runs around claiming "fraud!" like Roy does is already 1 foot in wingnutville. Add to that the usual gibberish about "2nd Law" violations and he takes the next step all the way in.

    Also speaking frankly, your whole linked site is a Gish Gallop of epic proportions. If you would like to select the 1 specific item that you feel Roy's whole case rests upon, do so and someone here will engage you on that. On the appropriate thread.

    One way to best utilize this site is by looking at the argument structure via taxonomy:
    http://www.skepticalscience.com/argument.php?f=taxonomy

    Or you can just use the Search Function in the UL corner of every page. Just plug in a term like "2nd Law" and you'll get something like this.

    BTW, Roy is welcome to come here openly. We don't bite.
  29. photeki @127, the linked article immediately demonstrates that Roy Clark is yet another in the long line of supposed "skeptics" who attempt to refute the theory of the greenhouse effect with out first bothering to learn what it is. Specifically, he attempts to show that the CO2 effect is saturated by discussing back radiation only. The greenhouse effect is not based on back radiation, and any discussion that assumes it is shows the author to be in complete ignorance of the theory they purport to refute. You will find a basic introduction to the greenhouse effect here. Read it carefully. Notice how the relevant factors are the Top of Atmosphere radiative balance, and that no mention of back radiation is needed. And for the record, if you work out the radiative physics for an increase of CO2 at the TOA, it does result in significant changes in radiative forcing, of 3.7 W/m^2 per doubling of CO2.
  30. photeki,

    Hint... anyone who includes lots of words and graphs and numbers, but no actual mathematics, is being lazy and trusting to common sense and "thought processes" to qualify everything while quantifying nothing.

    More directly... his perspective and opinions are totally worthless.

    Is it not peer-reviewed because he's afraid the process is flawed, or just because he's so demonstrably wrong? How often do people get to walk onto the floor of the U.S. Mint and demand their fair share of freshly printed bills, because the money-review system is flawed and unfair and they deserve more?
  31. Bob Loblaw, over here I said I answered "yes" to the question: ""Do you think human activity is a significant contributing factor in changing mean global temperatures?"" which I claimed put me in agreement with 97% of climate scientists. My thought in a nutshell was that CO2 is represents the largest forcing change over the 20th century, so "significant contributing factor" makes sense. You asked "What kind of model could be used to support a claim of "significant contributing factor", but would not also have an estimate of sensitivity built into it?"

    Using a model without sensitivity built in: the rise in CO2 is 6% per decade so the rise in forcing from CO2 per decade is 5.35 * ln (1.06) which without any feedback (lambda is 0.28 K/W/m2) means 0.087C per decade rise due to CO2. The observed rise per decade is 0.2C Now the question boils down to: is 43% of the rise in temperature per decade due to CO2 assuming no feedback a "significant contributing factor in changing mean global temperatures"?

    My answer is yes, that is a significant contribution.
    Response: [DB] Please take the model "hammer" discussion to the "Models are unreliable" nail.
  32. DB, I will take any model discussion there. I should point out here that using the same simple (no model) equations I get 2.4C per doubling of CO2. I'm sure someone else will point this out, but fast feedback in my post above disproves my claim of low sensitivity that I made on the other thread.
  33. Eric,

    I would also point out that simultaneous to adding CO2 to the atmosphere, we are seeing the sun enter a quiet phase, and we are adding dimming aerosols to the atmosphere (a short lived exercise in "global cooling" that will end when fossil fuel consumption ends, while the CO2 will remain).

    These two factors represent negative forcings which are holding the rate of warming down to a mere 0.2C per decade. This suggests that when the sun wakes up and the dimming aerosols (pollution) are no longer being added to the atmosphere, actual warming will be even greater than the 2.4C per doubling that you are currently calculating.

    For more on this look at Huber and Knutti.
  34. Eric: as per the moderator's comment, I have posted a reply over in the models thread.
  35. Sphaerica, I have replied on the "it's the sun" thread here Regarding aerosols, the stratospheric variety are very low http://data.giss.nasa.gov/modelforce/strataer/ and I would like to know on an appropriate thread if that is more or less important than tropospheric aerosols that you refer to.
  36. I'm on a quest to find peer-reviewed papers specifically testing the enhanced greenhouse effect by raising CO2 levels in a volume of atmosphere in the lab. I'm looking for a fistful of more tightly controlled examples of those experiments you see on youtube.

    Not OLR or DLR in the atmos, not spectroscopic tables, just the meat and potatoes physical lab test.

    Checked every citation for Tyndall's papers. Nothing. Tried various search terms in google scholar. Nothing.

    I begin to imagine that this experiment has never been submitted for peer review! If anyone knows of such papers, or can tell me the right search terms to use to find them, that would be much appreciated. I plan to offer them up to Ari for a new list @ http://agwobserver.wordpress.com/index/, and to have them standing by for the undead hordes.
  37. barry: "the meat and potatoes physical lab test."

    I think you need to explain just exactly what it is you mean by this.

    For example, if what you want is a simple demonstration that CO2 really does absorb IR radiation, then there are gazillions of commercially-available systems for measuring CO2 in air using IR spectrometry. e.g., Licor.
  38. Do you have anything yet, barry? Maybe I'm wrong, but I'm not sure people do that kind of stuff anymore. They certainly don't publish it. You might ask over at science of doom.
  39. barry
    strictly speaking, there's no lab experiment possible on the enhanced greenhous effect. It is like asking a lab experiment on the gravitational collapse leading to the explosion of a supernova. Climatology shares with astronomy and other fields of science the characteristic of reproducible and controlled experiments being impossible.
    But then, knowing the radiative properties of GHGs and the structure of the atmosphere you know what to expect. Whoever knows even a little bit of the two does not question the atmospheric greenhouse effect, self-styled skeptics only question its magnitude.
  40. I have an idea for an experiment, and have identified a suitable industrial partner, however I have been unable to attract sufficient funding from the Natural and Environmental Reseach Council. They say I should just use a model instead.

    More seriously, to perform a physical experiment you would need to have a colum of atmosphere tall enough to exhibit a significant lapse rate, which pretty much rules out any lab based experiment. The basic mechanism was first suggested by Calendar and the first quantative analysis performed by Gilbert Plass in the 1950s. That is probably the closest you will get.
  41. By the way, David Archer and Raymond Pierrehumber (of RealClimate) published a book a while back called "The Warming Papers", which is essentially a collection of some of the key historical landmark papers on climate change, with commentary from the authors. So if you want to find out the historical undepinnings of climate change research, the Warming Papers is an excellent place to start. ALL skeptics should get a copy of it and read it so they know the true depth of what they are skeptical of.
  42. Following up several points in one place...

    Although a controlled experiment of "the greenhouse effect" is not possible (we're doing an uncontrolled one, however), many, many parts of atmospheric science are amenable to controlled lab experiments - such as IR characteristics of CO2 and other gases, scattering effects of aerosols, and much other physics-related issues. There isn't any simple "global climate theory" - it's a compendium of many aspects of physics and biology; some with extremely strong evidence, others with less. A specific question can be answered with specific details, but if the question asked is "What's the Answer to Life, the Universe, and Everything", then answering "42" is probably not an answer to the question you really want to know.

    I know I've seen the table of contents of "The Warming Papers" on-line. Many of the papers contained in it are freely available for download, too. (Try Google Scholar.)
  43. Coming from a geological background, I would also point out that climate theory is pretty successful at predicting the surface temperatures of other planets/moons given atmospheric concentration, TSI and albedo. Regard each planet as a lab experiment.
  44.  

     

    The data from The European Project for Ice Coring in Antarctica shows results that are inconsistent with those presented here.  I did a scatter plot of CO2 vs. temperature for the 800,000 years represented by that study.  The first thing I noted was that the current point is way, way, way far away from the other 799.  That suggests by itself that there is a fundamental structural difference in what’s going on today vs. the past. Next, I plotted the climate equation using the maximum value of λ, 1.2.  It was way below the actual data points.  Then I estimated the value of λ which  would best fit the historical data (leaving out the current point because it is so far off).  The result was a value of 20.7 which is an order of magnitude larger than the maximum value stated here of 1.2.  Finally, I fit the best linear relationship.  It’s R square, .79, was better than that of the log fit, .76.  Can anyone give me a scientific explanation of what’s going on here?

     

  45. Regarding post # 64 by Stephen Baines:


    I asked a question about the law of conservation in a different thread and rceived some very interesting and compelling - to me - answers from Tom Curtis and Bob Loblaw.  They were clear and very helpful!

    Philosophically, I think it is important to be skeptical AND curious because the two fundamentally drive knowledge.  The two above mentioned men have been extremely helpful in presenting science as I remembered it, but with much more fidelity.

    I can only add here, questioning the limits our predictive powers, is that mother nature freely associates.  I trust the science and I consider models as useful tools to help point to a condition that is possibly very harmful to our future.  I cannot ignore, however, what I see...and for me it is sobering. 

  46. I did not read this entire thread, so forgive my question.

    There was a discussion above about co2 sequestration.  I understand that the ocean's ability to 'buffer' additional co2 can be helpful at first blush.  But buffering mechanisms, to my way of thinking, are trade-offs if you like.  From my own botany and soil science background I understand that the chemical equation will 'buffer' in the other direction as well if conditions permit.  Doesn't the buffered co2 bother us?  I don't see it as a long term benefit; if we stop introducing co2 into the air today, the level can drop to a point where some of the co2 is re-released into the atmosphere...or is my science off?

  47. Not sure its been covered yet, Is a 250ppm co2 laden atmosphere thinner than a 400ppm co2 laden atmosphere.

    Is it thicker in depth and does it let the same amount of solar radiation through?

  48. vonnegut, This is covered by the post from Tom Curtis at 125, CO2 is not a big absorber of visible light or ultra violet or the wavelengths of much of the IR we recieve from the sun.

    Incidentally, see my post at 126 for an example of how to deal with getting something wrong.

  49. I’m interested in the effects of CO2 on outgoing radiation, I have some questions.

    1. If an infinitely thin line were extended out perpendicular from the earth, how far would it extend before it reached a 99.9% probability (aprox.) of coming in contact with a CO2 molecule?  At 280 ppm and 400 ppm.

    2. When a CO2 molecule re-radiates, what is its efficiency? I.e. energy in vs energy out.  An analogy would be a number of steel balls in a row, each ball does not impart all of its energy to the next. After a certain number of balls the output is almost zero. The energy is absorbed as heat in the balls.

    3.  Would the long wave radiation in the CO2 bands ever reach the top of the atmosphere by the relay mode?

    4. What other gases emit long wave radiation when heated. I.e. the IR we see at the top of storm clouds.

    5. How much would the earth’s temperature rise if all long wave radiation (CO2 bands) were filtered and showed up as heat in the lower atmosphere?

  50. Others might have the numbers at their fingertips but here is some very quick answers.

    1/ To make any sense of this question, I think you are really meaning, how far would a photon of suitable wavelength travel before it hit a CO2 molecule. I dont know the exact no.s but pretty much 100% by 10m.

    2/ you are mixing up macroscopic (heat) and microscopic here. Think what "heat" means in the collision between photon and CO2. As such, the "efficiency" is 100%.

    I think you get a better idea of what is going on if you look up Radiative Transfer Equation for the diffusion model, and also Beers Law (Beer's-Lambeth law). A bit much for a comment reply.

    3/ Yes - pretty much the only way IR exits the atmosphere.

    4/ Not sure I follow you but do you mean what are the other greenhouse gases, then prominent are water vapour, CH4, O3,NO.

    5/ Dont really follow this at all. What CO2 does is absorb outgoing IR and then when it reradiates some of that re-radiation is going down (and by same path warms the surface). The gas itself doesnt heat.

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