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This is what so fascinates me about the denialist thought process -- they'll look at graphs of Earth's emission spectrum which were produced using radiative transfer theory, eyeball the graphs, conclude that CO2 is saturated and that any additional CO2 will have no further effect, then completely ignore the exact same mathematics that created the graphs which say that CO2 is not saturated and that it is, and will continue to be, an incredibly important factor in the surface energy budget. It's mind-boggling.
What you don't seem to get, Maxx, is that the "diminishing returns" concept you decry as being ignored by "AGW believers" is in fact inherent in the very concept of climate sensitivity -- every doubling, whether it be from 100ppm to 200ppm or 500ppm to 1000ppm, will have the same effect on temperatures; that is, a 1C increase. So although the absolute increase in concentration is 5 times larger in the 500-1000ppm scenario than the 100-200ppm scenario, the ratio of final to initial concentration is the same, and thus the temperature response will be the same. Another way of putting it is that, as concentrations increase, it takes a lot more CO2 to get the same effect.
BUT that effect is not, and will never be zero, as the U of Chicago link notes. If you'd actually take the time to read that link I think you'd find it to be incredibly informative.
For homework, let's try a little though-experiment: To simplify things, let's take a planet very much like Earth in size and distance from the Sun, but with a uniform surface and zero albedo, and call it planet A. Let us add a single isothermal layer of atmosphere to A that is completely transparent to incoming shortwave radiation from the Sun and completely opaque to outgoing IR from the planetary surface. We could provide a more quantitative description of this scenario, but suffice to say that the surface is now warmer with an atmosphere than it would be without. That being said, you might call this atmosphere "saturated", yes? Now let's add a second layer with properties identical to the first. What happens? Using your original logic we might conclude that this second layer has no effect on surface temperatures because the first was already saturated, but is this actually the case? The answer is no. The increase in temperatures would be less going from 1 layer to 2 than from no layers to 1, but it would still warm.
This is a very basic question, with variations of it found in almost all introductory atmospheric thermodynamics or radiative transfer texts, with the take home point being that "saturation" is irrelevant.
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Maxx
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Clearly it wasn't a strawman. I'll try again: THIS IS WRONG. Did you not read anything I wrote above?
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What that means to me is that any additional CO2 to the atmosphere should have less of an effect than previous additions. It doesn't mean it won't have any effect but you can't even define how much our previous emissions affected the temperature. Obviously, there is no convincing evidence that the 100 ppmV that we may have contributed to changed the temperature much from what it would have been naturally if our industries never existed. It is about a degree warmer than a hundred years ago and even that increase seems to be following the previous trend so blaming it on CO2 is more about wishful thinking on your part IMO. Sorry for bursting your bubble.
Jeff take a closer look at figure 4-5 here: http://forecast.uchicago.edu/chapter4.pd...
This figure contains 4 graphs that are exactly on point. Each graph shows IR absorption for a given CO2ppm.
Upper Left shows absorption for 0ppm - no absorption in the 600 to 800 band
Upper Right shows absorption for 10ppm - significant absorption in the 600 to 800 band
Lower Left shows absorption for 100ppm - shows a little more absorption in the 600 to 800 band
Lower Right shows absorption for 1,000ppm - very slightly more absorption in the 600 to 800 band
The biggest jump in absorption is the first 10ppm of CO2. When CO2 is increased to 100ppm (graph lower left) you see a little more absorption but it's not a very big increase. And finally the last graph at the lower right is 1,000ppm and you can hardly tell the difference in the adsorption curve from the 100ppm graph.
So these graphs argue against you. You've provided good evidence AGAINST you're own argument.
These graphs show that once 100ppm of CO2 is achieved, the effect of adding more CO2 has very little effect. And that's exactly what me and Kano were saying.
I had posted this graph before:
http://wattsupwiththat.files.wordpress.com/2010/03/heating_effect_of_co2.png
It was not said that adding more CO2 will not cause more warming, it was said that adding more CO2 now we have reached 400ppm will only add miniscule warming, the first 400ppm gave approx 0,8 degrees C by empirical measurements and it was estimated that another 400ppm would give maybe another 0.1C or less.
Of course continuing to increase CO2 will cause further temperature rises, but in such decreasingly smaller amounts it would be impossible to measure.
Even 100% CO2 would not give us another 1 degree C.
The fact that the amount of energy that a carbon dioxide molecule can absorb decreases with temperature does say that it will require larger doses of carbon dioixde to create the same additional effect. (The law of diminishing returns) This absolutely does not mean that adding more carbon dioxide will have NO effect.
Don't give up. Some people come to YA with legitimate questions and are open to legitimate answers.But the likes of Pat, Madd Maxx, Sagebrush, NW Portland Jack and other hard core denialists are not interested in the truth. They either ignore the evidence, or if they acknowledge it at all, they claim that it is a lie and post videos of what looks like graphs taped to see-saws.
I'm not up to speed on this subject so unfortunately I can't address this question.
However, it does bring up and interesting thought. We talk about climate sensitivity being the effect on temperature of a doubling of CO2 concentration. If the CO2-temperature relationship is not linear, then wouldn't climate sensitivity be higher at low concentrations and vice versa? In other words, if you mention a figure for climate sensitivity, then don't you need to specify at what concentration you are talking about?
Your first statement appears erroneous: The "rise in CO2 diminishes as concentration rises."
What you are evidently driving at is the rise in heat retained as a function of cumulative CO2 emissions, not the ability of the atmosphere to retain CO2.
You are giving deniers what they want.
You argue with them until you are blue in the face, which helps the smarter ones learn how to lie less clumsily, and then when you eventually make a mistake, the dumb ones pounce. You learn nothing, and no flat-earther, or Holocaust denier, or fanatical Marxist, or birther, or religious zealot, or believer in the resurrection of Elvis, or Koch-Wattsup climate science denier dupe/liar EVER changes his mind, no matter how much time you waste arguing with him.
So apparently I have been called a walking contradiction because I stated that the rise in CO2 diminishes as concentration rises but then state it hasn't happened (Meaning there is still quite a bit of radiation at CO2 absorption wavelengths to be retained). Lets go over this in detail shall we?
First lets us look at the frequencies CO2 absorbs at related to the greenhouse effect. There are a couple but the major one is centered in a band at 667cm^-1. (Note: This band stretches out past 750cm^-1 in one direction.)
http://www.tp.physique.usherbrooke.ca/experiences_fichiers/Fourier/References/CO2.pdf
Now we look at what will occur if CO2 increases it's concentration in the atmosphere. See figure 4-5 below.
http://forecast.uchicago.edu/chapter4.pdf
It looks like there is still quite a bit of energy to be absorbed in this region. And measurements show this to be the case as we look at the frequencies associated with the atmospheric window and the changes within it.
https://workspace.imperial.ac.uk/physics/Public/spat/John/Increase%20in%20greenhouse%20forcing%20inferred%20from%20the%20outgoing%20longwave%20radiation%20spectra%20of%20the%20Earth%20in%201970%20and%201997.pdf
http://journals.ametsoc.org/doi/pdf/10.1175/JCLI4204.1
http://www.eumetsat.int/Home/Main/Publications/Conference_and_Workshop_Proceedings/groups/cps/documents/document/pdf_conf_p50_s9_01_harries_v.pdf
Here's a question. If someone states that the amount of energy CO2 is able to retain decreases as concentration increases does that automatically mean that the total amount of energy that the molecule is able to retain has been reached? I'm sure anyone with the least bit of understanding in logic would state no. The user, and apparently questioner, in the linked thread below, however, figures differently.
http://answers.yahoo.com/question/index;_ylt=Am4y8lzBkKXkgtYlw8ma1lv_5nNG;_ylv=3?qid=20130613173350AALzH6l
And here is the question: How many times does this need to be brought up in here before it finally sinks in for those that are still stuck on the CO2 and saturation question?
It was not said that adding more CO2 will not cause more warming, it was said that adding more CO2 now we have reached 400ppm will only add miniscule warming, the first 400ppm gave approx 0,8 degrees C by empirical measurements and it was estimated that another 400ppm would give maybe another 0.1C or less.
Of course continuing to increase CO2 will cause further temperature rises, but in such decreasingly smaller amounts it would be impossible to measure.
Even 100% CO2 would not give us another 1 degree C.
The fact that the amount of energy that a carbon dioxide molecule can absorb decreases with temperature does say that it will require larger doses of carbon dioixde to create the same additional effect. (The law of diminishing returns) This absolutely does not mean that adding more carbon dioxide will have NO effect.
Don't give up. Some people come to YA with legitimate questions and are open to legitimate answers.But the likes of Pat, Madd Maxx, Sagebrush, NW Portland Jack and other hard core denialists are not interested in the truth. They either ignore the evidence, or if they acknowledge it at all, they claim that it is a lie and post videos of what looks like graphs taped to see-saws.
I'm not up to speed on this subject so unfortunately I can't address this question.
However, it does bring up and interesting thought. We talk about climate sensitivity being the effect on temperature of a doubling of CO2 concentration. If the CO2-temperature relationship is not linear, then wouldn't climate sensitivity be higher at low concentrations and vice versa? In other words, if you mention a figure for climate sensitivity, then don't you need to specify at what concentration you are talking about?
Your first statement appears erroneous: The "rise in CO2 diminishes as concentration rises."
What you are evidently driving at is the rise in heat retained as a function of cumulative CO2 emissions, not the ability of the atmosphere to retain CO2.
You are giving deniers what they want.
You argue with them until you are blue in the face, which helps the smarter ones learn how to lie less clumsily, and then when you eventually make a mistake, the dumb ones pounce. You learn nothing, and no flat-earther, or Holocaust denier, or fanatical Marxist, or birther, or religious zealot, or believer in the resurrection of Elvis, or Koch-Wattsup climate science denier dupe/liar EVER changes his mind, no matter how much time you waste arguing with him.
So apparently I have been called a walking contradiction because I stated that the rise in CO2 diminishes as concentration rises but then state it hasn't happened (Meaning there is still quite a bit of radiation at CO2 absorption wavelengths to be retained). Lets go over this in detail shall we?
First lets us look at the frequencies CO2 absorbs at related to the greenhouse effect. There are a couple but the major one is centered in a band at 667cm^-1. (Note: This band stretches out past 750cm^-1 in one direction.)
http://www.tp.physique.usherbrooke.ca/experiences_fichiers/Fourier/References/CO2.pdf
Now we look at what will occur if CO2 increases it's concentration in the atmosphere. See figure 4-5 below.
http://forecast.uchicago.edu/chapter4.pdf
It looks like there is still quite a bit of energy to be absorbed in this region. And measurements show this to be the case as we look at the frequencies associated with the atmospheric window and the changes within it.
https://workspace.imperial.ac.uk/physics/Public/spat/John/Increase%20in%20greenhouse%20forcing%20inferred%20from%20the%20outgoing%20longwave%20radiation%20spectra%20of%20the%20Earth%20in%201970%20and%201997.pdf
http://journals.ametsoc.org/doi/pdf/10.1175/JCLI4204.1
http://www.eumetsat.int/Home/Main/Publications/Conference_and_Workshop_Proceedings/groups/cps/documents/document/pdf_conf_p50_s9_01_harries_v.pdf
Here's a question. If someone states that the amount of energy CO2 is able to retain decreases as concentration increases does that automatically mean that the total amount of energy that the molecule is able to retain has been reached? I'm sure anyone with the least bit of understanding in logic would state no. The user, and apparently questioner, in the linked thread below, however, figures differently.
http://answers.yahoo.com/question/index;_ylt=Am4y8lzBkKXkgtYlw8ma1lv_5nNG;_ylv=3?qid=20130613173350AALzH6l
And here is the question: How many times does this need to be brought up in here before it finally sinks in for those that are still stuck on the CO2 and saturation question?
