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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To add to Dave’s response the reason why the CO2 laser emits strongly at the 10.6 Micron level is because it is not just CO2 but a mixture of gases including He and N2 that is inside the laser. That mixture is balanced in precise proportions that allow the CO2 to move from the excitation state emitting a 10.6 micron photon, and then down through various states to the ground state without shedding other photons, where it can then be excited again. The CO2 can move through the lower states by shedding vibrational energy to the other molecules, some of which shed energy to the container wall. Air just does not have the right proportions of gases to support CO2 in this absorption band, nor a container wall, and therefore air is very transparent at 10.6 microns. Gas proportions effect absorption. One of the many complexities, and no I do not understand the quantum mechanics (quantum state shifts) involved but it is important.
Well Lbd the surface of the earth isn’t a CO2 laser so it is emitting at wavelengths which CO2 will absorb given the proportions of gases in the air. The earth does emit some IR at 10.6 and that just escapes.
Oh, and none of what I’ve written implies that I think we are going to get Venusian temperatures here. There is no way to generate that much CO2, we don’t have sulfur clouds, and I believe H20 is a strong negative feedback. Yes, negative not positive, because of clouds and because water vapor is lighter than air and thus can act as a heat pipe working fluid. Like someone said above however a negative feedback cannot be greater than it’s driver. Thus adding CO2 will drive temperature up, and if you keep adding it then temps will keep going up.
Brian Macker says:
May 9, 2013 at 5:45 pm
“…and therefore the outer layers of CO2 will be radiating less energy with the same lower atmosphere temp.”
CO2 radiates energy at specific levels. No more, no less. But, when it is spread out at higher altitude, there is much more surface area to radiate, increasing as the square of the radius. When the thickness of the layer increases, the area at the bottom decreases, and the area at the top increases, due to the spherical distribution. This produces less efficient back-radiation to the planet and more efficient radiation to space. Result: cooler planet.
There is no fundamental physical reason that the heating due to CO2 must be monotonic with increasing concentration. It is only required that the energy it radiates back acts to raise the surface temperature above what it would be without any CO2 at all. But, the partial derivative of surface temperature with respect to concentration can be positive, negative, or zero.
daveburton says:
May 9, 2013 at 7:36 pm
“Of course you don’t want to talk about it, because you must surely know that it’s silly.”
Actually, there are many possibilities. But, I agree, it is silly to discuss with someone who not only does not know what he is talking about, but insists on repeatedly demonstrating it.
When you are in a hole, stop digging.
I didn’t claim it is monotonic. The thickness of the atmosphere compared to the diameter of the earth is so thin that the difference in area between the sphere defined by the surface of the earth and the surface of the top of the atmosphere that still has CO2 is negligible. Hotter CO2 radiates more energy than colder. It radiates more at the whatever wavelengths [it] can.
Adding more CO2 doesn’t cause the existing CO2 to spread out, silly. It causes increased density at all levels. It is just that at the top there is next to none so it causes that boundary to move up.
That was “it can” not “I can”.
[Is that the right place? Mod]
Bart says:
May 9, 2013 at 9:34 pm
Brian Macker says:
May 9, 2013 at 5:45 pm
I did err previously in saying that increasing the mean altitude of the layer causes a decrease in surface temperature. The surface temperature function appears likely to be monotonic in Rlo/Rhi, where Rlo is the radius of the effective lower boundary, and Rhi is the radius of the effective upper boundary. If we set Rlo = a – d/2 and Rhi = a + d/2, where a is the median altitude and d is the depth, then we can easily show that Rlo/Rhi increases for increasing a, and decreases for increasing d. Since the function is monotonic in the ratio, it behaves in the same manner. In fact, you can pick a to be any radius which remains within the layer, and find that increasing the depth always cools the surface.
I realized this dynamic when discussing Willis Eschenbach’s “Steel Greenhouse” here. Although the thought experiment is only analogous to the true situation, I do not see any reason the result should not carry over.
Brian Macker says:
May 9, 2013 at 9:50 pm
“Hotter CO2 radiates more energy than colder.”
No. CO2 radiates energy it receives from the ground back to it. That is the whole basis of the GHE. Some of that energy gets radiated back to the planet. Collisions do not generally cause photon emission, so the ambient temperature is not relevant.
Yes Brain I understand how the laser emits that’s not the importance where it emits it also absorbs that is what QM is all about.
What makes a laser media is the fact that it behaves strangely in that it can absorb yet transmit that frequency that is because most of the energy goes into resonant modes. All the other gas mixtures are there to help efficiency of the CO2 by assisting the optical pump and aid in cooling the tube.
Normal negative gain media don’t behave like that they absorb the emission in a one way process because they don’t resonate and block the transmission as you see with visible light going down in an ocean.
It is one of the interesting things about laser media is the absorbed frequency must also be transmissive otherwise the beam would in effect be blocked by the gas or media in the tube or optical cavity. It’s why not all elements can be made into a laser media.
If you look at the standard rules of a creating and evaluating laser media
(http://www.rp-photonics.com/gain_media.html)
1.) a laser transition in the desired wavelength region, preferably with the maximum gain occurring in this region
2.) a high transparency of the host medium in this wavelength region
So for a laser media you want absorption yet transmission and that’s because those two things are separate things just because something absorbs does not mean it won’t transmit or as Dave wants it blocks at that frequency.
10.4-10.6um from CO2 emissions are not important from Earth science point of view I agree but they do show how wrong Daves argument about absorption and blocking is.
Brian I thought of an easy way to invert the problem on you.
Basically your argument is 10.6um CO2 laser emission passes thru the atmosphere without really interacting with it and heads out to space. At a layman level that is sort of fine but you are ignoring the QM reality that it isn’t anything like that the beam is fully and continually interacting with the CO2.
So here is the inversion for you does increasing the CO2 level change the transmission characteristics of the the 10.6um beam ….. your argument is it shouldn’t do anything right because they don’t interact.
Want to have a guess what happens???
I will give you a sneak snippet … want to guess why the US Navy spent millions of dollars studying what the effects might be on there new toy 10.6um laser
http://connection.ebscohost.com/c/articles/59526563/climate-change-anticipated-effects-high-energy-laser-weapon-systems-maritime-environments
If you want the technical background
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA501519
See this has nothing to do with climate change its the physics of transmission of infrared thru the atmosphere.
@mpainter.
I asked a physicist this question and his reply was that to increase energy uptake by a IR receptive molecule you would have to increase insolation. Surface radiated energy was within the emission spectra of these molecules so would not be adsorbed. If a molecule was saturated with energy, remember these so called molecules are under energy bombardment as long as the sun shines so reach radiative equilibrium, saturated, and remain at that point. Remember equilibrium is reached when energy in equals energy out. This equilibrium is reached due to high energy solar radiation not low energy radiation from the surface. They cannot get hotter than the radiative equilibrium temperature otherwise this would not be at equilibrium. They loose energy through radiation and kinetically through collision with other molecules. Also energy levels dictate the heat path, ie., hot to cold and never cold to hot as required by the theory of the GHE.
See http://www.climateofsophistry.com
This site has several papers on energy flow, the GHE, written by an Canadian astrophysicist Joseph E Postma.
TimTheToolMan says:
May 9, 2013 at 4:57 pm
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.
No that’s not necessary, increasing the CO2 concentration by the amount proposed would reduce the IR losses from the surface thus causing the temperature to increase. Only a small increase in the temperature would be required to reach the supercritical state, in fact in the tropics sufficiently high temperatures already exist.
This article seems pretty flakey to me. I know Skeptical Science is not popular here but they do address this issue with some pretty straightforward points: yes, you do need a lot more CO2 (“blankets”) for each extra degree for warming,(as is clear in the IPCC reports despite the author’s lame conspiracy theory) but a lot more CO2 is exactly what we are going to get: http://www.skepticalscience.com/exponential-increase-CO2-warming.htm
skepteco says:
May 10, 2013 at 7:39 am
Yes, no doubt that is why Global Warming has been accelerating for the past 15 years.
Only, it hasn’t. In fact, it hasn’t even been warming at all. The idea that the missing warming is “in the pipeline” is obviously a flail of desperation.
Skeptical Science has a lot of nice, pat, straightforward if you will, points on a lot of climate related subjects. It isn’t popular here because it is sophomoric and generally wrong.
Being a motor head, I always use a hp/speed analogy. Almost any motorcycle will go 100 miles per hour. Getting to 120, well that takes more power. Getting to 140, well that takes even more. Going above 140? Now you’re talking big horsepower. I think it’s a good analogy as the horsepower difference between getting to 100 mph and 160 mph is more than triple.
Alberta Slim says:
May 9, 2013 at 4:18 am
John F. Hultquist says:
May 9, 2013 at 12:45 am
” [Fn]……………………etc.
. . . the ball is missed and rolls on the ground . . .
When energy is released by a molecule there is no preferred direction. Some up. Some sidewise. Some down. Any direction happens. Thus, radiation that starts in a direction away from one of Earth’s surfaces is as likely to end up back there as anywhere else. A surface might then absorb or reflect the energy. If the energy is absorbed, say by pavement, then the molecules of that move more rapidly – warm – giving a higher temperature. This is a temporary state because the warmed object will (1) radiate more then the cool one and the energy is sent on its way again, or (2) something in contact with the surface will be warmed – water might evaporate, O2 or N2 might warm and the air expand, thus conduction and convection work to move the energy higher into the atmosphere where it can be radiated to space. The ir-interactive gases (H2O) being the most abundant by far simply slow the loss of energy from the system. Because there is a delay in loss there is a slight warming.
Note if there is more in-coming solar radiation (insolation) the surface and the atmosphere will respond as the processes of conduction, convection, and radiation move the energy around and back to space. CO2 is a bit player in these processes .http://www.esrl.noaa.gov/gmd/ccgg/about/co2_measurements.html
Atmosphere with 3% water has about 30,000 ppm of H2O to about 400 ppm of CO2. The absorption bands overlap so additional CO2 is of little importance. That’s why there is a hunt on for a multiplier effect – also mentioned under the heading “sensitivity.”
Bart,
“No. CO2 radiates energy it receives from the ground back to it. That is the whole basis of the GHE. Some of that energy gets radiated back to the planet. Collisions do not generally cause photon emission, so the ambient temperature is not relevant.”
A collision doesn’t have to cause a photon emmission. It only needs to transfer heat. If the collision is just right it can result in bringing the CO2 to a vibrational frequency at which it can shed (at random) a photon of infrared light.
Heat can be transferred between all the modes, and also effect velocity. CO2 can gain and shed vibrational energy to photons at the right wavelengths. Two colliding molecules of CO2 with the same lower vibrational energy can collide and separate with some of the vibrational energy transferring from one to the other, resulting in one at an even higher state, and one at an even lower one. Collisions can result in the conversion of velocity changes into vibrational energy and vice versa. All these conversions are symmetric. Plus CO2 can do the same with other molecules and atoms that are in the air, and with solid dust particles.
When air is warmer there is an overall average higher velocity and energy content to it, and so more chance that collisions will result in the excitation of a greenhouse gas in it to the proper vibrational frequency at which it can shed a infraredd photo.
Sure CO2 can adsorb and reemit a photon of easily between collisions. This is because it is always moving between vibrational states that hav an energy gap that matches the quanta of energy of the photon. Since the molecules spend way more time between collisions than the do colliding then of course it is not likely to drop to a lower state and shed a photon during a collision.
The fact that in order for a greenhouse gas to adsorb a photo it must move between two states that a have a proper energy difference for infrared, means that it is in the exact energy state at which it can shed it, by dropping back to the lower state. This makes it easy to adsorb and release a photon before the next collision.
There is nothing stopping a CO2 molecule from absorbing an infrared photon as vibrational energy and then transferring it to another molecule, atom, or dust particle as a velocity change. CO2 lasers depend on this fact to get the CO2 back to the ground state by shedding vibrational energy to the walls (of the N2 intermediary). CO2 in the laser at the lower vibrational states shed vibrational energy to N2 in collisions and then N2 sheds to the wall.
If what you said were true then you could never heat a gas using infrared light. Heck, you could never heat any gas with any light of any kind. Which is baloney. You seem to think that the aborbed energy can ONLY, not preferentially, be converted back to light. This is wrong. Some percentage of light absorbed can and does result in a temperature rise in the gas.
According to you if there were two 100% CO2 gas planets closely orbiting each other as a binary system, and one was hotter than the other, they would exchange infrared light, but the temperature of both would be unaffected by the partner. Such a planet a 0 C could start with a partner at 100 C, or at -50 C and it would not make a difference to how it’s temperature would change. It would exchange infrared photons, but never cool nor heat.
Presumably if such a 100% planet were floating in space it would shed infrared to space yet never cool. Whatever infrared impinges on it would merely be reemitted, and none of the heat content stored in the velocity of the molecules could every convert to vibrational energy then infrared. The planet would stay warm forever since it is isolated by a vacuum from shedding heat via contact with other objects.
Ridiculous.
John Marshall, That’s only on the side facing the sun.
… also remember that the atmosphere is much closer to the earth. So even during the day half of the surrounding space points to earth, most of the rest to space, and a tiny circle towards the sun. Depending on how high you are in the atmosphere there is going to be differing influence of each. For example at night low in the atmosphere, say near the surface, the ground has much greater influence than space. While high in the atmosphere at night it is space that has the most influence. Oh, and part of the impinging infrared at any point in the atmospher comes from the atmosphere itself.
Far more intelligence is displayed in this exchange of ideas than the typical (unfortunately) series of rants and counter-rants that add up to the food-fights disguised as comments at climate blogs. A tip of the hat to you gentlemen for being gentlemen! HL Mencken
LBD, “but you are ignoring the QM reality that it isn’t anything like that the beam is fully and continually interacting with the CO2” No, I’m not. The air is very transparent at this wavelength so in layman’s terms there is next to zero interaction with anything in it. If there were strong interaction then it would NOT be transparent, in layman’s terms. You can understand all this by empirical measurement, with no need to even know what is going on quantum mechanically. Just like I can tie my shoe without knowing about QM and even though our universe is QM from top to bottom.
Bart says:
May 9, 2013 at 9:34 pm
Brian Macker says:
May 9, 2013 at 5:45 pm
“…and therefore the outer layers of CO2 will be radiating less energy with the same lower atmosphere temp.”
CO2 radiates energy at specific levels. No more, no less. But, when it is spread out at higher altitude, there is much more surface area to radiate, increasing as the square of the radius. When the thickness of the layer increases, the area at the bottom decreases, and the area at the top increases, due to the spherical distribution. This produces less efficient back-radiation to the planet and more efficient radiation to space. Result: cooler planet.
This is nonsense, the Earth’s radius is ~6400km, at an atmospheric emission height around 10km there isn’t much more surface area!
daveburton says:
May 9, 2013 at 7:36 pm
“Of course you don’t want to talk about it, because you must surely know that it’s silly.”
Actually, there are many possibilities. But, I agree, it is silly to discuss with someone who not only does not know what he is talking about, but insists on repeatedly demonstrating it.
When you are in a hole, stop digging.
Good advice, you should take it.
Bart says:
May 9, 2013 at 10:06 pm
Brian Macker says:
May 9, 2013 at 9:50 pm
“Hotter CO2 radiates more energy than colder.”
No. CO2 radiates energy it receives from the ground back to it. That is the whole basis of the GHE. Some of that energy gets radiated back to the planet. Collisions do not generally cause photon emission, so the ambient temperature is not relevant.
But collisions can prevent emission which is why emission depends on pressure and temperature, near the surface the mean time between collisions is much less than the emission lifetime for CO2.
Brian Macker says:
May 9, 2013 at 9:10 pm
To add to Dave’s response the reason why the CO2 laser emits strongly at the 10.6 Micron level is because it is not just CO2 but a mixture of gases including He and N2 that is inside the laser. That mixture is balanced in precise proportions that allow the CO2 to move from the excitation state emitting a 10.6 micron photon, and then down through various states to the ground state without shedding other photons, where it can then be excited again. The CO2 can move through the lower states by shedding vibrational energy to the other molecules, some of which shed energy to the container wall. Air just does not have the right proportions of gases to support CO2 in this absorption band, nor a container wall, and therefore air is very transparent at 10.6 microns. Gas proportions effect absorption. One of the many complexities, and no I do not understand the quantum mechanics (quantum state shifts) involved but it is important.
The N2 is important because it is excited in the laser by an electric discharge, the excited energy state is a very close match to an excited energy level of CO2 and collisionally excites that CO2 energy level. From that excited state emission to a lower excited state takes place emitting a 10.6 micron photon (or 9.4). In order for a transition to occur there must be a population inversion so that lower level is depopulated by collision with the He gas in the tube. Absorption of this frequency by the atmosphere requires sufficient of these lower states in the atmosphere, however since it’s an excited state not a ground state that is rare.
Brian Macker says:
May 11, 2013 at 5:15 am
“Collisions can result in the conversion of velocity changes into vibrational energy and vice versa.”
We are speaking specifically of emissions in the IR spectrum. There, the major effect of collisions is line broadening, which is second order.
Besides, you are putting the cart before the horse. The lower temperature of the upper atmosphere does not prevent GHG molecules from radiating. The lapse rate of temperature in the atmosphere exists because of the radiation of GHGs in the upper atmosphere. If they did not radiate, the temperature gradient would disappear.
Phil. says:
May 11, 2013 at 6:53 am
“This is nonsense, the Earth’s radius is ~6400km, at an atmospheric emission height around 10km there isn’t much more surface area!”
0.3% more. That may be small, but so is the change in temperature with altitude which Brian is suggesting results in greater surface temperature.
A scientific view of this post can be found here:
http://scienceblogs.com/stoat/2013/05/09/ive-not-found-much-of-interest-to-write-about-tonight-and-story-submissions-have-been-a-dry-hole-lately/
REPLY: Actually turned out to be nothing more than an errant spam filter issue -Anthony