The political target of limiting the effect of Man-made global warming to only +2⁰C can never be attained.
Guest essay by Ed Hoskins
According to well understood physical parameters, the effectiveness of CO2 as a greenhouse gas diminishes logarithmically with increasing concentration and from the current level of ~390 ppmv, (parts per million by volume). Accordingly only ~5% of the effectiveness of CO2 as a greenhouse gas remains beyond the current level.
This inconvenient fact is well understood in the climate science community. It can be accurately modeled using the Modtran program maintained and supported at the University of Chicago.
The logarithmic diminution of the effect of CO2 is probably the reason why there was no runaway greenhouse warming from CO2 in earlier eons when CO2 levels were known to be at levels of several thousands ppmv.
Remarkably, IPCC Published reports , (TAR3), do actually acknowledge that the effective temperature increase caused by growing concentrations of CO2 in the atmosphere radically diminishes with increasing concentrations. This information is in their report. It is well disguised for any lay reader, (Chapter 6. Radiative Forcing of Climate Change: section 6.3.4 Total Well-Mixed Greenhouse Gas Forcing Estimate).
The diminishing percentage effectiveness of CO2 as a greenhouse gas as acknowledged by the IPCC and its concomitant diminishing temperature effect are as follows:
increment cumulative
0-100 ppmv: according to David Archibald / Modtran data ~2.22°C ~2.22°C
100-200 ppmv: plants die below this level of CO2 +~0.29°C ~2.51°C
200-300 ppmv: noted as the preindustrial CO2 level +~0.14°C ~2.65°C
300-400 ppmv: current level IPCC attributes all as Man-made +~0.06°C ~2.71°C
400-600 ppmv: business as usual till 2100 +~0.08°C ~2.79°C
600-1000 ppmv: improving levels for plant growth +~0.06°C ~2.90°C
Accounting for the diminution effect the actual temperature reductions achievable, the calculated achievable values are in the range of few hundredths to a few thousandths of a degree Centigrade. As the margin of error for temperature measurements is about 1.0°C, these miniscule levels the temperature effects for all the efforts of those nations attempting to control their CO2 emissions, (only about 12% of world CO2 emissions), are marginal, immeasurable and thus irrelevant.
These minute temperature changes have to be seen in the context of normal daily temperature variations at any a single location of 10⁰C to 20⁰C. It can be as much as 40⁰C to 50⁰C over the course of a whole year.
Although the IPCC tacitly acknowledges that this crucial diminution effect with increasing concentrations effect exists, it certainly does not go out of its way to emphasise it. Like the Medieval Warm Period, that they attempted to eliminate with the Hockey Stick graph in 2001, the panel knows that wide public knowledge of the diminution effect with increasing CO2 concentration would be utterly detrimental to their primary message.
“Man-made CO2 emissions are the cause of climate change”.
The IPCC certainly does not explain these devastating consequences for the CAGW theory in their Summary for Policy Makers. This is because the IPCC is an essentially political organisation, that is solely tasked with the promotion and presentation of Man-made Climate Change from CO2 emissions, as an accepted and non-contentious fact for world’s politicians.
Thus the IPCC is entirely misleading in its central claim for Policy Makers, as they say:
“Warming of the climate system is unequivocal. Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.”
Any unquestioning, policy making reader is lead to assume that all increasing CO2 concentrations are progressively more harmful because of their escalating Greenhouse impact. But the opposite is so.
From the present concentration of atmospheric CO2 at approaching 400 ppmv, only ~5% of the effectiveness of CO2 as a Greenhouse Gas remains.
This can only give rise to a maximum of a further of ~+0.21°C. Thereafter beyond 1000+ ppmv the effect of increasing levels of CO2 can only ever be absolutely minimal even if CO2 concentrations were to increase indefinitely.
It is for this irrefutable physical fact that the widely held alarmist policy ambition
“to constrain Man-made temperature increase to only +2.0 °C”
could in fact never be reached, however much more Man-made CO2 was emitted.
It is impossible to ever reach the much vaunted policy upper limit of +2.0 °C that has been promoted by politicians as a target upper limit of temperature effect caused by man-made CO2 emissions.
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The best place to go for understanding CO2 behavior is the hard physics area most of which have absolutely nothing to do with climate science.
Knut Ångström the son of Andres after whom the unit is named faced almost the equivalent of an adverse finding over his experiment on radiative theory. The reason being was because if the result stood then QM theory was wrong a fact E.O. Hulburt noticed and replicated and re-did all the experiments.
It is via the subsequent enquiry that we know that Knut entrusted most of his experiment to his lab assistant Herr J. Koch who basically fouled it all up.
I see WUWT did an article by Anthony(Story submitted by John Keh) on the argument between Arrhenius and Ångström (http://wattsupwiththat.com/2012/04/30/a-tale-of-two-altitudes-how-stratospheric-temperature-is-de-coupled-from-the-surface-temperatures/) what he misses in all that is the fact Ångström is most certainly wrong as shown E.O Hulburt showed because for it not to be wrong put QM in a degree of trouble to be blunt it was an invalidation and so it was a big deal to QM.
Most of the Knut Ångström story is in Swedish which is why it’s probably not well known to those outside the QM field.
E.O. Hulburt is a rather interesting man who I encourage all to read his papers and the Naval research laboratory still gives out an annual award named in his honour being the E. O. Hulburt Annual Science Award.
The bottom line is Knut Ångström and classic physics is wrong and QM prevailed and repeating an argument settled 100 years ago is pointless because if Ångström was right then QM must be wrong and we know that isn’t so.
Phil writes “It wouldn’t become liquid it would be a supercritical fluid which has a density less than that of water so your scenario doesn’t apply.”
It would only be a supercritical fluid if its temperature was over about 30C and since the average temperature of the earth is considered to be around 15C then it would be liquid or possibly even solid.
daveburton says:
May 8, 2013 at 2:19 pm
Even though CO2 levels are measured in parts-per-million, there’s nevertheless already so much CO2 in the atmosphere that it blocks nearly all of the IR that it can possibly block. So adding more CO2 doesn’t have much effect on temperature. For CO2′s main absorption bands, we’re way, way past the CO2 levels at which the IR is all absorbed.
———————————
Well, for one thing, you emission to space in the 14 micron band occurs high up in the troposphere. That means that when you add more CO2 to the atmosphere, the level at which the radiation from CO2 can be effectively emitted to space moves up, and because of the lapse rate, this is at a lower temperature, and because of gravity there is a lower concentration of CO2 (the pressure is lower). The net of this all is that there will be less emission in the 14 micron band and the surface has to heat up.
When it does so the emission from the surface shifts to the blue, e.g. more emission from the surface in regions where CO2 does not absorb. Elegant
TimTheToolMan says:
May 9, 2013 at 7:49 am
Phil writes “It wouldn’t become liquid it would be a supercritical fluid which has a density less than that of water so your scenario doesn’t apply.”
It would only be a supercritical fluid if its temperature was over about 30C and since the average temperature of the earth is considered to be around 15C then it would be liquid or possibly even solid.
Not a chance! Even if the amount of CO2 was added at present temperature the vapor pressure of CO2 would be over 10atm, at that concentration the surface temperature would rise to super critical values (and then the pressure would increase to 92atm (the original proposition).
How about this for a “layman'” explanation.
If you would build a greenhouse with single thickness of glass, you would observe an increase in temperature. Great! I will add another thickness of glass to increase the temperature. It may of increased some but not like the original…I’l just add another pane. Hardly any measurable increase. That’s what we mean by a logarithmic effect.
Bart said on May 9, 2013 at 12:15 am, “daveburton says, ‘…such a mechanism still could not reduce the warming effect of any other factor (like CO2) all the way to zero. No negative feedback mechanism, no matter how strong, can do that.’ As I explained above, this is not true in general. Please stop saying it.”
You are confused, Bart. If temperature doesn’t change, then a feedback mechanism based on temperature changes cannot possibly have any effect whatsoever.
Bart continued, “If you do not understand integral control, then you do not understand one of the most basic types of feedback, and you prejudice knowledgeable members of your audience against you.”
I have a degree in Systems Science. I understand control systems very well, including PID industrial controllers (the “I” stands for “integral”). Regardless of how you set the “I” knob, you still can’t reduce the effect of other inputs to the system all the way down to zero.
Positive feedbacks amplify an effect, and negative feedbacks attenuate it (though with time delays they can also cause oscillation). But no negative feedback mechanism can ever attenuate an effect all the way to zero.
What’s more, if you’re really claiming that temperature integrated over time is negatively coupled to atmospheric water vapor content (i.e., a history of warmer air causes reduced atmospheric water vapor content), then, pray tell, how on earth do you think that could possibly work? What could cause such a thing?
Kevin Vaughn asked, “how does such a small part of the atmosphere absorb all of the infra red [in its absorption bands]“
To understand the answer, consider an analogy: a liter of pure water in a clear, 10x10x10 cm cubic jar or box, and one drop of food coloring. Our (99% N2+O2) atmosphere is like the water, and CO2 is like the food coloring, except that the “color” of CO2 is from absorption in the invisible IR range.
If you add one drop of food coloring to the liter of water, it will very noticeably tint the whole liter. But one drop is only about 0.05 ml, so one drop in one liter is 0.05 / 1000 = 0.00005 = just 50 ppm.
But consider: although the atmosphere is less dense than liquid water, it is miles thick. The full thickness of the atmosphere is about the same mass as a 30 foot deep layer of water.
Your cubic jar of colored water is only about four inches thick. So to get an equivalent thickness to the Earth’s atmosphere, you’ll have to stack up 90 of those jars of colored water in a 30-foot-long row.
Now, look through (or shine a light through) the row of 90 jars of colored water. Imagine how deep the color will be, from just 50 ppm food coloring.
That’s why just a few ppm of a trace gas can significantly affect the spectrum of the light which passes through the Earth’s atmosphere.
daveburton says:
May 9, 2013 at 12:29 pm
“Regardless of how you set the “I” knob, you still can’t reduce the effect of other inputs to the system all the way down to zero.”
That is precisely what integral control does, and my respect for your opinions has just plummeted to near zero.
“What’s more, if you’re really claiming…”
This statement is worth debating. The former is not. Concede the former, or forget further discussion.
The author said
According to the Guinness book of World records “Temperatures in Verkhoyansk (67⁰33’N, 133⁰23’E) have ranged 105⁰C 188⁰F, from -68⁰C -90⁰F to 37⁰C 98⁰F”
Werner Kohl,
“So my question: Which effect leads to such a high temperature on Venus?”
The greenhouse effect of the CO2 despite the claims of this article.
The simple answer is that having more CO2 acts like a thicker layer of insulation. The visible light from the sun goes straight through and heats what it hits. The infrared radiation emitted by the heated surfaces has to work its way up through more CO2 (more insulation) before escaping.
Here is the long answer:
Think of CO2 as an insulation which doesn’t loose it’s R factor even when compressed.
So lets imagine a uninsulated house with a copper shell, and a small furnace continually burning the same amount of fuel. This will generate a steady amount of heat that needs to be radiated from the exterior of the house to maintain a stable temperature. Suppose that given an outside temperature of 0 degrees the interior stays a 60 degrees. Since it is uninsulated the surface of the copper shell is at 60 degrees too. So the exterior of the house at 60 degrees can loose exactly all the heat from the furnace to the 0 degree outside air.
Now lets insulate the house with one inch of this special R factor stable compressable insulation on the outside surface of the copper shell. We will ignore the trival addition of surface area this causes. I’m also going to simplify and assume that you loose ten degrees of temperature for every one inch of insulation.
So if it was at 60 degrees in the house the additional one inch of insulation causes the exterior to drop to 50 degrees (while the interior is still 60). At 50 degrees not as much heat is lost to the 0 degree air. Think about it, if the exterior was 0 degrees it would lose zero heat to the air, so as it gets colder it looses less heat. In order to balance the interior temperature will rise till the exterior again is at 60 degrees. It has to rise to 70 to be able to have the exterior be 60 (there is ten degree drop over the thickness of the on inch of insulation).
Now if you add an additional one inch of insulation the temperature drop across this layer is again ten degrees and now the exterior is 50 degrees. Again this is too cool to radiate all the heat from the furnace. The outside surface temperature would have to rise back up to 60 degrees again in order for the heat to be radiated. So the interior temperature will again rise by ten degrees to accomplish this. Now it is 80 degrees inside the house, 70 degrees after the first inch of insulation, and 60 degrees after the second inch. Now this insulation is compressible. We could compress the two inches down so it is only one inch wide, and still generate a 20 degree drop over the entire depth of the insulation. We can keep doing this, add another inch and the interior has to be a 90 in order for the exterior to be at 60. Another and it goes to 100. Etc.
Now the R factor of the insulation depends on several factors. One of which is how much radiation it intercepts going out. Others include how fast heat is conducted, or convected through the material. If you make the insulation thinner some factors are going to overwhelm others. When the insulation is very thin the R factor is going to go down because some percentage of the radiant energy will pass right through without ever hitting any molecule to be absorbed and reradiated.
Say in our imaginary insulation that 50% of radiation just passes through one millimeter of material. Well if you double that two millimeters you now capture half that 50% that passed through to have a 75% capture rate. Now one inch of our imaginary material in 25 mm thick. So only 1/2^25 of the radiation can get through. That’s 1/33554432 or only 0.000003%.
The fact that one inch of our insulation blocks 99.999997% of the direct radiation does not mean it is only radiating .000003 percent of the heat. It just means that the other factors, like conduction and convection are the main means by which the heat moves through the material. In fact 100% of the heat being produced by the furnace is traveling through the insulation and is being radiated by the exterior surface.
One of the means that heat travels through the material is via internal reradiation and absorbtion by the material. For every point A inside the material the point B one inch further towards the exterior is ten degrees colder. Point A would like to radiate directly to point B but cannot because the intervening material blocks 99.999997% of radiant energy. I can radiate .000003 percent of its heat directly and it does. But point B also back radiates in the other direction .000003 percent of what it can. Point A also radiates 50% of it’s heat directly to a point only one millimeter away, and that point 50% of what it can back. However those two points being much closer are also much more similar in temperature. So interior radiation can play a factor, even if we don’t have any conduction or convection, but it is NOT easy for the heat to move through the material in this way.
If you are confused, like many here, you might think that the fact that 99.999997% of the radiant heat (infrared) is blocked by one inch this insulation that adding more insulation cannot accomplish anything. While it is true that you can keep on increasing the insulation and can only hope to block at most .0000003 percent more of the DIRECT radiation that is NOT how most of the heat is being transported at that point anyway. Most of the heat is passing via conduction, convection of air in the spaces of the insulation, and interior radiation. In fact at that point 99.99997% of the heat is being transferred by the other factors which totally depend on the amount (not thickness) of this special material. I said amount because we can shrink or expand the material and the same amount of material causes the same amount of insulating.
Now even with this imaginary material things are more complex than I have explained. It wouldn’t even be possible for one thing, because when you compress the material the molecules will be closer together. Since temperature is a function of how fast the molecules are vibrating (or moving in a gas) they will have more opportunites to collide, and convection would increase. Nor is this imaginary material a perfect analog for CO2. I will not go into the differences, but it is close enough.
So once you have gotten to the point where CO2 is blocking 99 percent of the radiation it is not true that you can only insulate another 1%. At that point the direct radiation is only 1% of the problem. Over 99% of the heat is moving through the atmosphere by other means. That amount of CO2 will have a certain R factor due to how slow the heat moves through the material by those other means. It will cause a certain amount of temperature rise. Simplistically, if you double the CO2 from that point then you get double the insulation value.
There are however all sorts of other factors that counteract a simple doubling of R value for a doubling of CO2, negative feedbacks Pressure goes up in the lower layers allowing more conductive transfer. Heat is conducted to other greenhouse gasses which reradiate at wavelengths that can pass right through the additional layers of CO2, etc. These factors are negative feedbacks on the insulative value of having double the CO2.
The pressure on Venus is not the cause of the increase in temperature. It is the side effect of having so much more CO2. Venus has 92 times as much atmosphere to begin with, and a much larger percentage of that atmosphere is CO2. Venus has a 96.5 percent CO2 atmosphere. Ours has only around 400 ppm. Not sure of exact percent because you have to adjust for molecule weight but it is close to 0.04 percent. There is 2412 times the concentration of CO2 on Venus and 92 times as much atmosphere. That’s a whopping 221950 times as much CO2 for the heat to get out through.
The negative feedbacks are fairly powerful because the temperature difference between earth and venus is no where near the multiple of the difference in CO2 (plus we have other greenhouse gasses like water I did not count). Heat conducts very well through an atmosphere compressed to 92 bar, and there are winds on Venus and thus much convection, the same velocity winds in dense atmosphere carries more heat content, etc.
Hello Brian,
thank you for your long explanation. I will read it tomorrow (here in Germany it’s shortly after midnight.
But in between one question:
I’ve computed the CO2 ratio between the earth and Venus to 1:227641 – that’s almost identical to your ratio.
As we know dT is proportional to the logarithm of (C2/C1)
where C1, C2 are the concentrations of CO2
Let dT be 3 K if the concentration is doubled (I think it’s an assumption where IPCC doesn’t protest). So we have this equation:
dT = 10 * log10(C2/C1) = 10 * log10(227641) = 53.6 K
If we assume that the natural GH effect of the earth is 33 K (I know that this is not a very good assumption) so the total GH effect on Venus should be 87 K.
If we make the assumption that the energy from the sun which comes down to the surface is radiated back to space from the whole surface we have this equation:
(1-0.750) * 2615 W/(m² * K^4) = 0.9 * Sigma * T^4
where
0.750: albedo
2615 W/(m² * K^4): solar constant at Venus
0.9: emissivity (I know no better value)
Sigma: Stefan-Boltzmann constant
==> T = 238 K
Compared to the mean surface value of 737 K which I find in Wikipedia the GH effect of 87 K is far away from explaining that very high temperature.
How can this be?
davidmhoffer,
“It seems clear from the article that the author meant increasing CO2 indefinitely through the burning of fossil fuels. The entire article is about that. Implying that the author meant otherwise adds little value to the debate.”
Baloney, you CANNOT increase CO2 indefinitely by the burning of fossil fuels. Eventually you run out. So that cannot be what he meant. Either that or it is yet another flaw in the article. That he makes these mistakes is not my problem.
Fact is, that if you keep adding CO2 you can get temperature increases going all the way up to that of Venus. There is no 5% upper bound on the increase. The limiting factor is no absorbtion. The limiting factor is the amount of fossil fuels, and other sources of CO2.
He is claiming that the amount of radition that can escape directly from the surface to space is the limiting factor. Which is nonsense. When you have 95% interception of infrared by greenhouse gases then the vast majority of infrared escaping the system comes from the upper layers of the atmosphere. Those upper layers are cooler precisely becasue they are heated from below and the atmosphere underneath is blocking much of the infrared. The closer you get to the surface the greater proportion of the surface generated infrared can heat the air. Assuming 95% then only 5% of the direct surface radiation is available to heat it, and yet that upper layer can radiate directly to the near absolute zero of space. Meanwhile air near the surface gets nearly 100% of the infared impinging on it from the surface, but cannot radiate directly to space (except for around 5%). 95% of the reradiation from air near the surface is being captured by higher layers of air which are way warmer than space. Thus it is much more difficult for it to get rid of that heat. That is part of the reason for the temperature gradient in the atmosphere.
Additionally the pressure gradient means that air higher up is naturally cooler (lapse effect). The heat vibrations near the surface need to be much more vigorous to support the 14 lbs per square inch pressure. Higher up, where the pressure is less a lower temperature can support all the air above it without collapsing. When you add more CO2 you are moving some of it higher where it is cooler and this is the part that can radiate to space. That higher cooler CO2 is an additional blanket over the lower CO2. Like the house with more insulation having a cooler surface radiating means higher interior temperatures.
Sorry, I forgot a “4” in my equation:
(1-0.750) * 2615 W/(m² * K^4) = 4*0.9 * Sigma * T^4
But the result T = 238 K was correctly calculated.
Brian Macker says:
May 9, 2013 at 3:01 pm
“Simplistically, if you double the CO2 from that point then you get double the insulation value.”
Very simplistic. And, not generally true. The distribution of the gas is extremely important. The surface temperature increases inversely with the mean altitude of the layer – increase the altitude, and surface temperature decreases, decrease it, and the surface temperature increases.
So, if you make it more dense, but move it to higher altitude, the two actions oppose one another, and the surface temperature may increase, or it may decrease, or it may stay the same.
Phil writes “Not a chance! Even if the amount of CO2 was added at present temperature the vapor pressure of CO2 would be over 10atm, at that concentration the surface temperature would rise to super critical values ”
Of course you can add whatever clauses you like into a hypothetical argument but the energy has to come from somewhere so you’re assuming that we’re adding CO2 AND supplying the energy to get it to the temperature where it becomes a supercritical fluid. You might as well assume the sun doubles its output to match Venus’ insolation and that the water vapour is lost to space too.
Werner Kohl,
Because is is way more complex than you are making it out to be. There are also positive feedbacks and a big difference between a atmosphere that is mostly non-greenhouse gas with a little mixed in vs. one that is nearly all greenhouse gas. The lapse effect is a positive feedback.
I understand the concepts but have not done this kind of math since I was a kid, and am not in the field. I can give you an example of something I would think was a positive feedback but I am not going to be able to compute it’s strenght vs other factors. The fact that most of the visible light is absorbed at the earths surface, vs on Venus where it is absorbed at the top of the cloud layer is going to have an effect.
On venus the less dense upper atmosphere is heated, and most of the energy then needs to move up from there. If you could magically drop the temperature Venus to say earth temperatures I think the following would happen. Most of sunlight would heat the tops of the clouds. Let;s pretend they are half way up the 92 bar at 46 bar height. The extra heat at that height is causing a certain amount of velocity to be imparted to the molecules. These higher molecules will bang on the lower ones transporting heat downward. The few percent of light that strikes the surface will also be heating from below. However the vast majority of energy will be moving both downward from the tops of the clouds and upwards from the tops of the clouds (some upwards into space). The same amount of sunlight being absorbed by a less dense material will bring it to a higher temperature. There will be more energy per molecule. So the fact this is being absorbed very high in the atmosphere means it will be getting hotter than if absorbed at the surface. There is still heat being pumped in at the surface but it cannot radiate past this higher temperature upper atmosphere. Since heat is being pumped in continuosly at the surface it must be hotter than the high temps above it in order to transport it upward.
Once equlibrium is reached no heat will be transported downward from the cloud tops. All of that will go upward. The few percent of heat impinging on the surface will travel upward. Because most of the heat is captured and radiated above the clouds I would expect the high atmosphere to have the most convection and winds. Since little energy can escape by radiation almost all the impinging energy will go into causing convection currents. Wind speed should be higher up higher in the atmosphere.
This is all speculation on my part. But you can see that there are complexities that your simple formulas do not take into account.
The profile of the earth atmosphere temperature with height is not a simple one of closer to the ground warmer either. As you go higher the temperature drops rises then drops then rises. The very top of the atmosphere has very little green house gas in it and so cannot radiate to space. It is being impinged by solar particles (and may also absorb some component of sunlight). So it is actually hotter than the layers below it. Things just aren’t so simple as your formula, and frankly I can’t tell you exactly why it is so hot on the surface of Venus but the vast quantities of CO2 play a role.
@Brian Macker:
Yes, I know that my calculation was very simple and that there are additonal effects. I’ve done it to get a scale of the greenhouse warming. I would not be surprised if the actual temprature differs by 50 K or a little bit more.
But if you are right the logarithmic relation between increase of CO2 and increase of temperature is not valid for Venus. The Venus is ~400 K (!) hotter than expected when assuming this logarithmic relation. By no way you can reach a rise of 400 K using a logarithmic relation.
Because of that I supposed that there are other effects contributing.
And because of that the greenhouse warming may be not the primary effect, so it cannot be quantified.
Bart,
“So, if you make it more dense, but move it to higher altitude, the two actions oppose one another, and the surface temperature may increase, or it may decrease, or it may stay the same.”
Density of the CO2 isn’t the important factor. It is thickness of layer containing CO2. More CO2 means more at higher elevations where as you admit it is colder and therefore the outer layers of CO2 will be radiating less energy with the same lower atmosphere temp. Just like with the house example. The bottom layers need to heat to raise the temperature enough transport the heat through the atmosphere to a higher level (and therefore raise temps on the greenhouse gases that are in the upper layers where it can be radiated directly to space). Several commenters have already pointed this out.
You seem to believe that more CO2 is going to make things colder. Also how the heck do you “make it more dense and move it to a higher altitude” that’s ridiculous. The density is a factor of the altitude and temperature.
I would like to hear all you gyro pseudoscience junkies explain how your microwave oven works and develop your classic physics stupidity to discuss it because you are faced with the same problem. Some real world reactions are simply beyond the reach of classic physics because they don’t even understand how the effects occur.
You will find many real world studies of CO2 laser beams interactions as they pass thru the atmosphere and the CO2-water interactions because it is a key understanding how high energy laser weapon pass thru the atmosphere for both land based and space based weapons. A reasonable overview can be got from the link (http://www.ausairpower.net/APA-DEW-HEL-Analysis.html#mozTocId18199) and nothing to do with climate science.
If you go back and read your own stupidity that most of you have written a CO2 laser beam couldn’t go very far in the atmosphere because it’s saturated and would be completely absorbed or some other stupidity.
It may interest some of you gyro gearloose types that publicly you can get the information on how 10.6um moves thru the atmosphere from up to 10Km from military publications (http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA187679). There is data available from space but it is largely still classified but you may pick up snippets here and there as usual on the web.
The science of water vapour continuum is not so well known from the hard sciences and military there is still currently no single accepted theory or model on reactions because it has a massive number of interactions and to be blunt before climate science debate it wasn’t considered important.
There is a reasonable summary of the current state on water vapour on the UK met board website (http://www.met.reading.ac.uk/caviar/water_continuum.html). The UK met board correctly states => “Thus, a deep controversy on the nature of the water vapour continuum still remains unresolved.”.
So hard physics science understands how CO2 emissions react they interest us, water vapour we don’t know so much about.
@rgbatduke says:
May 8, 2013 at 2:57 pm
Thanks for injecting some sense into this discussion. This is a water world, and CO2 has a tiny but key part in its on-going play. That CO2 line is “Don’t let me get below 200 ppm, or I’ll kill you!”
Eli Rabett said on May 9, 2013 at 9:20 am, “Well, for one thing, you emission to space in the 14 micron band occurs high up in the troposphere. That means that when you add more CO2 to the atmosphere, the level at which the radiation from CO2 can be effectively emitted to space moves up, and because of the lapse rate, this is at a lower temperature, and because of gravity there is a lower concentration of CO2 (the pressure is lower). The net of this all is that there will be less emission in the 14 micron band and the surface has to heat up.”
With more CO2 in the atmosphere, the IR within CO2’s absorption bands which is emitted from the surface is absorbed, on average, at an ever-so-slightly lower altitude. But since that altitude is just a few meters(!!), it doesn’t matter much. The transport mechanisms which move heat from the lower atmosphere to the upper atmosphere, where it can be radiated to space, work just the same, and the surface temperature is not much affected.
The only exception is for those IR wavelengths (mostly on the fringes of the two main absorption bands), for which CO2 is just a very weak absorber of IR.
Eli continued, “When [the surface heats up] “the emission from the surface shifts to the blue, e.g. more emission from the surface in regions [of the spectrum] where CO2 does not absorb. Elegant”
Interesting thought. That would be a negative feedback mechanism (helping to stabilize temperature), were it significant. But I doubt that it is.
So Dave if CO2 is this massively good absorber of IR and you fully understand the physics how can I pass a 10.6um CO2 laser beam thru the air not just a few meters but kilometers if I so desire.
Look carefully at what you said and your garbage classic physics predicts I shouldn’t be able to pass a CO2 emission like for a CO2 laser thru the air because the CO2 in the air will absorb it that’s what your saying.
See the problem yet?
I wrote on May 9, 2013 at 12:29 pm, “Regardless of how you set the “I” knob, you still can’t reduce the effect of other inputs to the system all the way down to zero.”
Bart replied on May 9, 2013 at 1:43 pm, “That is precisely what integral control does, and my respect for your opinions has just plummeted to near zero.”
No, it’s not. Adding a bit of negative integral feedback can improve the precision of a control system (at a potential cost in stability), but it cannot completely eliminate the effect of any other input. No feedback mechanism can do that, because, by definition, feedbacks react to an output of a system, and “feed back” to affect the inputs. Unless the output is perturbed, there’s no feedback.
I continued, “What’s more, if you’re really claiming that temperature integrated over time is negatively coupled to atmospheric water vapor content (i.e., a history of warmer air causes reduced atmospheric water vapor content), then, pray tell, how on earth do you think that could possibly work? What could cause such a thing?”
And Bart replied, “This statement is worth debating. The former is not. Concede the former, or forget further discussion.”
Of course you don’t want to talk about it, because you must surely know that it’s silly. There’s no plausible way that such a mechanism could work.
We know how warming increases evaporation and atmospheric water vapor content, and how cooling the atmosphere has the opposite effect, causing the water vapor to precipitate out, and since water vapor is a GHG this is obviously a positive feedback mechanism for temperature. But, contrary to wishful thinking, size matters, and the alarmists’ first error is in their failure to quantify the effect, which is actually quite modest. (Their second error is their failure to take into account various negative feedbacks.) But it is no good pretending that positive feedback from water vapor doesn’t exist at all. That’s just wrong.
You need to answer the question Dave how come I can pass a CO2 emission cleanly thru the atmosphere infact the only thing that will limit you is things like water vapour.
You state CO2 simply absorbs IR that’s your level of understanding I get it but lead also absorbs certain types of radiation I am sure you know that. Put enough lead in the way and your radiation can’t pass thru it I am sure you know that.
So how come I can’t put enough CO2 in the atmosphere to stop a CO2 laser passing thru it.
That’s the big problem O.E.Hulburt was working on in 1931 it’s not complicated how can something that is absorbing not block answer that answer your problem.
For others interested you can’t block a CO2 laser with CO2 because it is a positive gain medium.
The lead and radiation is a negative gain medium example the one classic physics is much more familiar with.
There is no way to understand why a CO2 laser can pass thru CO2 even though it absorbs at those frequencies under classic physics and to attempt to do so is stupid because there is no basis to understand it … if I told you radiation increased as it passed thru lead would you believe me because that’s the same issue?
That’s the very basic problem with people trying to understand CO2 and its behavior using classic physics it simply won’t work all we can do is sort of create a half baked lie.
All of the garbage written by most of the pseudoscience types in the above comments don’t even get the basic problem of trying to understand positive gain mediums .. end of story.
LdB asked on May 9, 2013 at 7:20 pm, “how can I pass a 10.6um CO2 laser beam thru the air not just a few meters but kilometers if I so desire… [despite] your garbage classic physics…”
Because 10.6 µm is not within any of CO2’s strong IR absorption bands. The major CO2 absorption band is centered around 14 µm, with narrower bands around 2.6 and 4 µm. Within those bands a photon can only travel a few meters through the atmosphere, on average, before it is absorbed.
(Also, strange things apparently happen if you punch up laser power levels high enough.)
Carbon dioxide lasers are complicated, and I don’t claim to understand them, but the physics of IR absorption by CO2 is not “garbage.”
10.6um is the dominant frequency of CO2 … classic physics says if I absorb at that frequency it shouldn’t pass thru it … and that’s your logic.
This is not some associated band of CO2 it is the dominate frequency.
Classic physics put CO2 in front of beam says it should block it and that’s the logic you have used above.
It’s blatantly wrong you can see it’s wrong a CO2 laser is emitting exactly CO2 absorption frequency to an incredible accuracy.
You don’t have to understand a CO2 laser to understand the problem your physics above just got smashed by an observation that CO2 is allowing a frequency it absorbs to pass thru.
Lets put this in perspective as you do to the bottom of the ocean it get darker because the water absorbs the light … if we did the same with an ocean of CO2 the beam would hit the bottom with no loss of intensity … SEE THE BIG DIFFERENCE.
Yes CO2 absorbs IR but it does not block it and that is why your explaination is garbage.
Classic physics can not explain positive gain media there is now ay to do it nor can I explain to you how your microwave at home works using classic physics either.
So the moral of the story is stop trying to understand CO2 absorption using classic physics you can’t do it and anything you try and explain will be blatantly and obviously wrong.