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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,A few corrections to last post (sleepy, I guess): I meant to say that because Earth didn’t burn up even with 20 percent CO2 in the air, it would have taken much more even than that for there to be extreme warming.
Ferdinand Engelbeen says:
May 8, 2013 at 2:35 pm
0-100 ppmv: according to David Archibald / Modtran data ~2.22°C ~2.22°C
Something wrong here: if you use Modtran for the first step, looking down from 70 km height, 1976 US standard atmosphere, no clouds or rain, the difference between 0-100 ppmv CO2 is near 7°C.
Modtran also says if you go from pre-industrial 280 ppmv to a double 560 ppmv, the temperature increase is ~0.9°C, which is quite different from the 0.14°C extra (from 300 to 600 ppmv) in your calculation. What is going wrong here?
Ferdinand Engelbeen says:
May 8, 2013 at 3:21 pm
“What worries me is the too low calculation by the author of the increase by Modtran for the first step 0-100 ppmv, which affects all following steps.”
I don’t know that I buy either yours or the author’s version, but at the moment I lean toward his. The writing is not altogether clear but he seems to indicate that his figures are drawn directly from the IPCC(TAR)
“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:”
Additionally,as I recall, the conventional value for the total GHE is 33C, the difference between Earth’s temperature with its atmosphere or without it. In comment above rgb indicates ” water already provides over 95% of our total GHE”, a value i suspect is close. You suggest that, just from 0-100ppm CO2 is responsible for 7C. 7/33 = 21.2%. You then suggest that doubling from 280ppm to 560ppm will yield another 0.9C. 7.9/33 = 23.9%. You don’t provide a value for the 1.4 doublings from 100ppm to 280ppm, but a rough interpolation would suggest that CO2 is responsible for a full third of the GHE. That’s fairly bold. although there does appear to be at least one spot on the planet where itis actually the case.
http://journals.ametsoc.org/doi/abs/10.1175/JCLI3525.1
Spectral and Broadband Longwave Downwelling Radiative Fluxes, Cloud Radiative Forcing, and Fractional Cloud Cover over the South Pole.
Abstract
Annual cycles of downwelling broadband infrared radiative flux and spectral downwelling infrared flux were determined using data collected at the South Pole during 2001. Clear-sky conditions are identified by comparing radiance ratios of observed and simulated spectra. Clear-sky fluxes are in the range of 110–125 W m−2 during summer (December–January) and 60–80 W m−2 during winter (April–September). The variability is due to day-to-day variations in temperature, strength of the surface-based temperature inversion, atmospheric humidity, and the presence of “diamond dust” (near-surface ice crystals). The persistent presence of diamond dust under clear skies during the winter is evident in monthly averages of clear-sky radiance.
About two-thirds of the clear-sky flux is due to water vapor, and one-third is due to CO2, both in summer and winter”
I assume you’re familiar with the temperature history at the South Pole over the last 40-50 years, so i won’t take the time to find a link.
Personally I suspect the global average contribution might be even smaller than the <5% that rgb suggests. If you, or anyone else, is interested in my speculation I posted a slightly shorthand version of it in a recent thread.
Dave Wendt says:
April 30, 2013 at 10:47 pm
http://wattsupwiththat.com/2013/04/30/the-paradox-of-consensus/#comment-1293027
It's about the twelfth time I've put it in a comment over the years, each time fully expecting my ideas to be quickly demolished. So far that hasn't happened. I could put that down to the incredible brilliance of my impeccable logic, although I suspect a more reasonable assessment would be that most of my comments are completely ignored.
Tonyb says:
May 8, 2013 at 1:53 pm
Phil
Have you got a graphic of some kind that demonstrates your point? It is difficult to visualise your comment especially as you provide mo actual figures or links.
It’s called ‘the curve of growth’, at very low concentrations the absorption is linear (B-L) at high concentration it’s square root, in between it passes through logarithmic which is where our current atmosphere is for the 15 micron band of CO2.
See e.g.:http://astrowww.phys.uvic.ca/~tatum/stellatm/atm11.pdf
Science of Doom did a piece on the curve of growth too.
http://scienceofdoom.com/2011/04/30/understanding-atmospheric-radiation-and-the-“greenhouse”-effect-–-part-twelve-curve-of-growth/
Relevant to this thread he has also showed the problems in Miskolczi’s analysis:
http://scienceofdoom.com/2011/04/22/the-mystery-of-tau-miskolczi/
The point, about the logarithmic decline in the ‘greenhouse gas’ effect of CO2 with concentration, and Bob Tisdale’s point, that the long-wave infrared radiation re-emitted back towards the surface in the ‘greenhouse gas CO2’ model can only penetrate the all-important ocean surface by a few mm and probably just increases surface evaporation, are very big flaws in the ‘greenhouse gas CO2’ hypothesis of anthropogenic global warming.
I think both are essential points to make in the Youtube movie.
And a very good layman’s illustration of the deep ocean penetration of directly incoming shortwave solar radiation but the ocean’s opacity to CO2-re-radiated, longer wave infrared radiation is the simple fact that the deep sea is blue and cold. It is mostly the shortest wavelength blue light that penetrates it. Some longer wavelength green, yellow and red light does get down to shallow depths (hence the colours of corals and tropical fish when snorkelling), but the sub-visible, longer wave infra-red wavelengths of heat re-radiated by CO2, do not get down to any depth at all.
David Banks says:
May 8, 2013 at 7:11 pm
Since water vapor and CO2 both trap heat at the same wavelength
They don’t, so your subsequent argument is moot.
TimTheToolMan says:
May 8, 2013 at 7:50 pm
Brian Macker writes “Just keep adding CO2 until you get to 92 bar of pressure at the earth’s surface. Then you have essentially recreated the Venusian atmosphere, and the surface temps would rise to 872 °F.”
No you haven’t “essentially recreated the Venusian atmosphere”. Venus has only trace amounts of water vapour in its atmosphere. If you were to hypothetically quickly add say 60-80 kms depth of what would become liquid CO2 under that pressure, then our ocean would still float on top of that to a depth of around 2-3kms and the oxygen/nitrogen atmosphere we have now would be atop that.
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.
Why would you assume it wouldn’t stratify?
Why should it?
As no sunlight would reach the 60-80kms of liquid CO2 then there is no reason to expect it to warm the planet in anything like the way Venus is warmed.
Why not, sunlight reaches the surface on Venus despite the dense clouds in the Venusian atmosphere.
I first became aware of the diminishing CO2 effect from reading Matt Ridley’s Angus Miller lecture. He quoted an IPCC report:
I asked about it on Eli Rabbett’s blog (Eli is reputed to be a chemistry professor) and he responded by admitted it was true but, of course, he embellished the feedbacks. He concluded:
http://rabett.blogspot.com/2013/04/eli-grabs-another-envelope.html?showComment=1366810476893#c2860151886663545408
Doesn’t matter if the hypothetical was possible. It was the authors hypothetical. He claimed that you could keep adding CO2 indefinitely and not get more than 5% increase. Which is false. How he was going to do this doesn’t matter. He can fly the stuff from Venus in spaceships for all I care. Seems like some here are as dense as the Venusian atmosphere if they don’t understand what a hypothetical is. We KNOW that this claim is false because Venus is an empirical example that falsifies it. We don’t need to do it here on earth because the experiment has already been run.
Brian Macker says:
May 8, 2013 at 10:16 pm
Doesn’t matter if the hypothetical was possible. It was the authors hypothetical. He claimed that you could keep adding CO2 indefinitely and not get more than 5% increase. Which is false.
>>>>>>>>>>>>>>>>
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.
What does MODTRAN give for the surface temperature of Venus? It must be a pretty useless model if it can’t predict the surface temperatures for all the known planets!
Ferd Berple: Your explanation is concise and, I think, correct. Atmospheric pressure is a function of earth’s gravity, which is a constant. Occam’s Razor in action?
dcfl51 said on May 8, 2013 at 3:02 pm, “Dave Burton, warmer air is capable of holding more moisture than cooler air. But observations made over the past 60 years show that global relative humidity has actually been falling… [link to “friends of science” material about middle tropospheric humidity]“
Relative humidity isn’t what matters when water vapor is considered as a GHG. It’s absolute water vapor content that matters.
Moreover, most water vapor is in the lower atmosphere. As you you go higher in altitude, temperatures drop, and so does the ability of the atmosphere to hold moisture, so water vapor content drops. At 7.5 km altitude (400 mb, which is middle troposphere), which is the altitude shown in this graph from the web page you cited, air temperature runs about -35°C, and it contains only minute traces of moisture.
Also, you need to remember that correlation does not imply causation. Assume, for the sake of argument, that it really is true that middle tropospheric humidity has been dropping over the last 60 years [which is questionable], and also that middle tropospheric temperature has been increasing over the same time period [which is also questionable], that still wouldn’t mean that atmospheric moisture content is inversely reliant upon temperature, which is what Arno claimed. There just doesn’t seem to be a plausible mechanism for such a causal relationship. There are many factors which affect either temperature or humidity, and could account for such trends.
Additionally, as Roy Spencer points out, “few people believe long-term trends in radiosonde humidities. [Miskolczi’s] result depends upon the reality of unusually high humidities in the 1950s and 1960s. Without those, there is no cancellation between decreasing humidity and increasing CO2 as he claims.”
But, more fundamentally, even if it were true that the warming of air caused it to retain less water vapor rather than more, 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. A negative feedback mechanism based on temperature can only reduce the temperature increase if temperature actually increases.
Mike H “It would be greatly appreciated if somebody could provide me with a layman’s way of explaining this to people”
The greenhouse effect is determined by how much radiation is SENT BACK into space vs ABSORBED from the Earth.
Angstrom did a simple experiment in 1900, which is confirmed today. A 20 in long column of CO2 at sea level all the way to 10000 ft height absorbs NO heat.
CO2 absorbs strongly, about 16% of the solar energy.
It does it however in a very narrow spectrum band.
All the energy in the CO2 spectrum is absorbed by even 60ppm CO2, 20% of the CO2 around.
That’s why that band is empty.
The only effect of extra CO2 is that that amount is a small change in the altitude at which the absorption happens.
*
By contrast, water vapor absorption is roughly proportional to the amount of vapor.
So water vapor is the main driver of greenhouse effects. Based on historic evidence, water vapor acts as a stabilizing thermostat.
daveburton says:
May 8, 2013 at 11:21 pm
“…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. 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.
Alberta Slim says: My question is this:
May 8, 2013 at 6:59 pm
Say you and a dozen friends (Fn) each have a tennis racket and there is just one ball. Someone, say F1, starts and hits the ball toward F3 who hits the ball toward F7. F7 hits toward F9, to F11, to F8. F8 hits the ball over a wall and into a lake. Have F1, F3, F7, F9, F11, and F8 trapped the ball? Do they have some sort of net gain or loss? Suppose F1 had hit the ball into the lake on first contact? What if everyone hit the ball twice before it sailed from the playing field? Suppose the ball is missed and rolls on the ground for 2 seconds before it is started on its way again?
Instead of saying that heat is trapped just say there is a delay of energy loss from the system. Then one doesn’t have to imagine friends expanding and floating into the upper atmosphere. [Note that this analogy doesn’t change if you have two dozen friends.]
~~~~~~~~~~~
A more scientific view is at the link below that shows what actually happens as a CO2 molecule responds to absorbed photons.
http://webphysics.davidson.edu/alumni/jimn/co2/pages/co2theory.htm
I still don’t understand the high surface temperature of planet Venus.
Assuming that dT ~ log(C2/C1)
(where C1 and C2 are concentrations of CO2) cannot explain a mean temperature of 737 K.
Is has been argumented that the high preesure explains the rise of temperature but I don’t understand this. If you compress a gas you observe such an effect. But this compression happened in far history so – after that long time – the excess heat should have been radiated to space.
So my question:
Which effect leads to such a high temperature on Venus?
Dave Wendt says:
May 8, 2013 at 8:35 pm
I don’t know that I buy either yours or the author’s version, but at the moment I lean toward his. The writing is not altogether clear but he seems to indicate that his figures are drawn directly from the IPCC(TAR)
No, he indicates that the first step (0-100 ppmv) is taken from the Modtran program. The Modtran program only calculates the change in outgoing IR, not a change in temperature, but if you calculate the outgoing IR at 0 ppmv and 100 ppmv, you must adjust the ground temperature offset from the 100 ppmv calcualtion to compensate for the loss of IR, until the same value of outgoing IR is reached as for 0 ppmv CO2. That gives a temperature increase of slightly under 7°C, not the 2.22°C of the author. Thus I suppose that someone of us did make a mistake…
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.
That is right, but it makes a lot of difference if the first step is 2.22°C or 7°C. With the latter, the increase from a doubling still may reach the “catastrophic” 2°C increase at the end of this century. Not that I expect such an increase and certainly not the “catastrophic” part, but that is what the IPCC expects from the average model increase…
but a rough interpolation would suggest that CO2 is responsible for a full third of the GHE
That is what the Modtran program for clear skies says and what the IPCC says (before any feedbacks). It is also what your reference for the South Pole indicates. I have no stake in this debate, so I am not going to discuss the reason for 5% or 30% of the GHG effect percentage between opponents…
@Adrian Clarkson O
Perhaps now you need to go forward to 1931 and read the paper from E.O. Hulburt that shows that Ångström and his assistant Herr J. Koch results were wrong both at experiment and theory, They should have got 1% not 0.4% if they did the experiment properly and the theory was at odds with both reproduced experiments and the newly emerging Quantum Mechanics calculations.
As I had tried to explain to many of the pseudoscience types on here QM gives a very precise calculation of what will happen and it is way beyond the stupidity of climate science or your garbage.
QM already knows that Ångström’s argument is trivially and stupidly wrong and we record it in history as such and it’s ridiculous that you go back to an argument that is settled way beyond your ability to argue it because you are trying to invalidate Quantum Mechanics.
So instead or repeating already dead and fatally flawed science Adrian read what Hulbert who was studying the new field of QM found happens when you mix water vapour and CO2 and that the result is entirely unexpected and inconsistent with classic physics but complete consistant with what QM predicted.
There is no classic way to explain to you what is happening the result makes no sense from a classic physics sense and that in a nutshell is why climate science is in the rather stupid loop it is stuck in and we even have nutcases that think the greenhouse effect doesn’t exist.
What gets up my nostril is the answer from science via QM is and has been available to people since 1931 and it is beyond the reach of classic physics garbage and any argument you can conjur up. QM tells you the answer both water vapour and CO2 are quantum active gases and they react with each and no you won’t be able to understand it using classic physics.
So lets see if you actually get up and read Hulburt’s paper and QM analysis and grasp that you and Angstrom are trivially and fatally wrong. Hopefully you will understand that how the greenhouse effect works is way beyond climate science stupidity because we have CO2 and water vapour lasers to confirm QM calculations. The unknowns in climate science that hard physicists can’t answer is what the positive and negative feedbacks are outside the main QM behavior of the gas mixture. We can’t answer those because the earth doesn’t have the precise control of a laser tube.
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.
So how does such a small part of the atmosphere absorb all of the infra red. There is a lot of space between the CO2 molecules????????? Aren’t you assuming that the CO2 blankets the whole atmosphere??
This still relies on using a property that CO2 does not have ie., to retain heat. Water vapour can but only through latent heat which is NOT the GHE.
If CO2 could heat the atmosphere as indicated then at 400ppmv it would be radiating in the near UV which would be easily picked up and measured.
Another thing, the GHG molecules in the atmosphere are saturated with energy through insolation. They cannot become supersaturated due to surface radiated LIR.
johnmarshall says:
May 9, 2013 at 2:39 am
Another thing, the GHG molecules in the atmosphere are saturated with energy through insolation. They cannot become supersaturated due to surface radiated LIR.
<<<<<<<<<>>>>>>>>>>>>>>>
A startling statement. Could you elaborate, please?
“Climate Science”: where refusal of perfectly honest men
to say they believe
in a
giant,
unfindable
unseeable
unquantifiable,
unmeasurable
light in the sky,
turned ‘on’ 24/7/365,
are banished as worse than the well documented criminal scammers they expose,
while “widely respected scientists”
point Home Depot thermometers at the sky – claiming without shame or dent to their teflon-like gloss, in a field where no number of infantile errors reveal incompetency,
“Look, the big CO2/Water-derived infrared light really is there!
Only to have to have the manufacturer of that instrument
be forced to finally, issue a statement: to stop such illucid ranting,
because the thermometer is tuned to reject CO2/Water-derived light,
due to false readings occuring.
Only to have that same “scientist” then grab an off-the-shelf infrared camera, and repeat the same claim:
and be lauded as a genius before his time.
——-
This is why real scientific thinking laughs in the face of the “science” that claims
experimental evidence is below it
instrumentally verified readings are below it,
and no number of infantile, childlike errors, disqualifies one as a “world expert.”
Where “statement of belief”
in the
giant,
unquantifiable,
unfindable,
unseeable,
unmeasurable light in the sky,
turned ‘on’ 24/7/365,
is roundly used, as sole qualifier
of the intellectual bona fides
for being a “member in good standing”
of “the widespread consensus” –
consenting to be termed
‘believer’ in
the giant,
unquantifiable,
unfindable,
unseeable,
unmeasurable light in the sky,
on 24/7/365.
The “science” where the likes of Eli Rabbet, Michael Mann, John Cook, Phil Jones, James Hansen, Peter Gleick, and Kevin Trenberth can not be fired, for any act no matter how eggregious,
and the entire rest of the civilized world, is instructed it’s best to be afraid they’ll be sued for demanding evidence of any claims they encounter, and that it’s best to just shut one’s mouth,
because it’s unseemly to confront “widely respected” so-called “scientists.”
The field where top “science advisers” are politicians, train engineers, mechanical engineers,
and daring people to arrest them in their scamming, is the stamp of “scientific integrity.”
The following is an excellent reference site concerning the greenhouse gas mechanism and related climate change questions. The author is classically skeptical from a strictly scientific perspective. (i.e. There appears to be no bias by the author.)
http://www.barrettbellamyclimate.com/index.htm
This is a review paper by the author of the site.
http://www.warwickhughes.com/papers/barrett_ee05.pdf
Greenhouse molecules, their spectra and function in the atmosphere
John F. Hultquist says:
May 9, 2013 at 12:45 am
” [Fn]……………………etc.
Thanks for that. I will check it out. Have to leave now, on a trip.
One quick thought. The IPCC says that some of my friends are hitting the ball back to the earth and heating it up. That seems to me, to be more than a delay of the ball reaching outer space.