9,25 – a factor that could close the global warming debate
Guest post by Frank Lansner (hidethedecline)
The CO2-sensitivity describes the warming effect induced by a doubling of the CO2 concentration in the atmosphere, and is thus the epicentre of the global warming discussion. Estimates of the CO2 sensitivity are very different, and the value range used by IPCC appears unlikely to physically impossible. To show this, I will focus on the factor “Fw” between the total CO2 warming and then the warming from a single doubling of CO2 concentration.
The total CO2 warming effect is obviously many times bigger than the warming from a single CO2 doubling. Example: When changing CO2 concentration from 5 ppm to 320 ppm we have 6 doublings. But on top of these 6 doublings, how much warming effect is introduced when CO2 concentrations are changed from 0 to 5 ppm etc? In the following I use the online model MODTRAN:
Fig. 1. Above is illustrated the warming effect of CO2 for 3 different climatic areas. Zero W/M2 represents the net forcing of the atmosphere fore a given scenario with CO2 concentration set to 0 ppm.
For each area is shown a clear sky scenario as well as a light rain scenario. All other variables in MODTRAN are left as the default values. The results from MODTRAN are total atmosphere outgoing radiation, and thus when changing concentrations of CO2 we get total atmosphere responses incl feedbacks if present.
Fig 1 Shows 6 doublings of CO2 concentration: 5-10-20-40-80-160-320 ppm where every doubling shows warming effect of similar size (–as could be expected due to the logarithmic declining effect of adding more CO2 to the atmosphere).
From the graph above we can see that the total CO2 warming effect today equals around 9 times the warming effect of one doubling of CO2 concentration.
Fig 2. For a better compare between the scenarios on fig1, these are now shown as %-values of the total CO2 warming effect for (Forcing) with today’s concentration of 390 ppm CO2, equals 100%. It appears that clear sky, rainy sky, Arctic area, tropics, subtropics scenarios has a very similar profile indeed and I find that this result shows that we can consider these %-trends to be rather global.
Fig 3. The average global CO2-doubling can now be calculated more accurate to be near 10,8% of the full CO2 warming effect at 390 ppm. (Or, the “CO2-sensitivity” warming effect is around 10,8% of the total CO2 warming effect, globally.)
Thus, the “best estimate” of the factor between total CO2 warming effect and the warming effect from one CO2 doubling – Fw – can be calculated. Best estimate (so far) Fw = 9,25.
CO2-warming-total (K) = 9,25 * CO2-warming-from-one-doubling (K) = 9,25 * CO2 sensitivity (K)
I have used MODTRAN for this result, but it is universal that the doublings must have near same warming effect and thus the individual doubling will have just some fraction of the total value. For now, the factor 9,25 is best estimate.
Hansen – CO2 sensitivity.
Now how does the factor 9,25 between total CO2 warming effect and CO2 warming effect from a single doubling support the viewpoints of James Hansen on CO2 sensitivity?
James Hansen often refers to a CO2-sensitivity of 6 K… 6 K warming effect for each single CO2 doubling:
Fig 4 James Hansens CO2 sensitivity of 6 K gives around 55,5 K of total CO2 effect using the factor Fw = 9,25. As the total warming effect of all greenhouse gasses is assumed to have a warming effect of approx 33 K, the Hansen CO2-sensitivity demands that the total CO2 related warming effect is bigger than all the greenhouse gasses effect combined.
The overall CO2 warming effect is supposed to be around 10-15-2% of the total warming effect of the atmosphere, here we use 15%. Since CO2 is assumed to account for 15% of the total 33K greenhouse effect on Earth, the CO2 total warming effect is around 5 K. So just ONE CO2 doubling of Hansen’s CO2 sensitivity of 6 K has a bigger warming effect than the total warming effect supposed to be possible.
It is therefore highly odd that Hansen’s claim of 6 K CO2 sensitivity has been taken seriously anywhere at any time.
Here the “greenhouse wheel” (see WUWT post Wheel! – – Of! – – Silly!) where supposedly scientists imagine that we by year 2100 can have warming of over 7 K in fact with less than one CO2 doubling to cause this:
Fig 5. To account for their 7 K temperature increase, they must have played with a CO2-sensitivity of perhaps 10 K? So these honourable “scientists” believes that one CO2-doubling might resemble a third of the combined earth greenhouse effect?
IPCC – CO2 sensitivity
Then, how does the factor 9,25 between total CO2 warming effect and CO2 warming effect from a single doubling support the viewpoints of IPCC on CO2 sensitivity?
IPCC AR4 viewpoints for the CO2 sensitivity :
http://en.wikipedia.org/wiki/Climate_sensitivity
IPCC “best estimate” of warming from one CO2 doubling is 3 K.
Using the Fw = 9,25 we learn, that if one doubling warms 3 Km then the total CO2 warming should be around 28 K ( = 9,25 * 3 )
We must then remember again that the total warming effect of the atmosphere is generally accepted to be near 33 K. The warming effect related to CO2 should then be around 85% of the total Earth atmosphere greenhouse gas effect. And without CO2, the atmospheres warming effect should be reduced to 15% of todays atmosphere…. On a globe with mostly water-ocean surface…
The IPCC numbers where each doubling of CO2 represents 3 K it simply does not fit at all with the total warming effect of the atmosphere.
IPCC then claimed:
“Values substantially higher than 4.5°C cannot be excluded..”
Well, 4,5 K for CO2 sensitivity gives a total CO2 effect of 41,6 K. This is 126% of the total earth greenhouse effect, so we could rephrase:
IPCC:
“Values of CO2 related warming substantially higher than 126% of the total greenhouse gas warming cannot be excluded..” …
Idso´s and Lindzens estimates for CO2 sensitivity.
What if we assume that CO2 is responsible for the 15% of the 33K greenhouse warming effect on Earth? This corresponds to 5 K. If true, the CO2 warming from one doubling should be
CO2 sensitivity = CO2warming-total / Fw
CO2 sensitivity = 5K / 9,25 = 0,54 K
So just using the generally accepted knowledge that CO2 sholuld account for around 15% of the total Earth greenhouse effect, and using the also generally accepted knowledge that total Earth greenhouse effect is 33K, then the CO2 sensitivity should be near 0,54K
Idso 1998 suggests 0,4 K, and Lindzen suggests 0,5 K these results appears sound and realistic in strong contrast to values from IPCC and Hansen.
Hansens 350 ppm ”safe level”
Fig 6. When working with CO2 – effect, one cant help wondering what Hansens ”safe level” of 350 ppm CO2 is all about.
Fig 7. NASA´s, James Hansen has claimed 350 ppm to be a safe level of CO2:
– Just 1,5 % less Warming effect from CO2 and we are “safe”.. ?
If CO2 has a total warming effect of 5 K – as previously calculated – the difference between the Hansen “safe level” CO2 warming and todays level is around 0,075 K.
I wonder if the peoble creating the 350 ppm demonstrations knows this?
I wonder how they will react when they find out.
Idso 1998:
http://www.int-res.com/articles/cr/10/c010p069.pdf
MODTRAN:
http://geoflop.uchicago.edu/forecast/docs/Projects/modtran.orig.html
“when changing concentrations of CO2 we get total atmosphere responses incl feedbacks if present.”
Kindly provide a reference showing that MODIS includes feedbacks.
Please also remember that the total greenhouse effect of 33K is for a planet with an albedo of ~0.3. If you removed all greenhouse gases the temperature would be 33K colder, but once ice feedback occur, the albedo would increase, and the temperature would fall even further.
Hi Anna,
Most scientist believes that it takes around 4 W/M2 to warm the Earth surface 1 kelvin – you dont agree?
Read: http://en.wikipedia.org/wiki/Climate_sensitivity
They say:
x = ΔTemp/ΔForcing * (3.7 W/m2)
Looks rather proportional to me.
And why on Earth should the change
355->356 W/m2
not result in a temperature change similar to
358->359 W/m2
??
Of course temperature and effect is proportional to a high degree.
K.R. Frank
Hi Mike Haseler, you write:
“OR TO PUT IT ANOTHER WAY, THE DESTROY THE CO2=GREENHOUSE WARMING MESSAGE”
I understand you only too well. But to be realistic, I cant attack all corners of the AGW card house in one go, in one blog entry.
If i did that, mentioned “all” I would end up with a huge mess, and no message coming across. therefore I just pick one argument, and show its problems. Its more realistic to get one point across by just mentioning the one point.
Next article perhaps we should look at the other planets atmpspheres, show that their insulating effect appears very unrelated to the particular gasses in the atmosphere – and thus make your point. But one thing at a time 🙂
K.R. Frank
Richard Telford
Thanks for interesting input. However if MODTRAN uses feedbacks or not is not relevant as I explained in the comment
September 8, 2010 at 3:13 am .
You see, the problem of each CO2 doubling causing a similar heat effect has nothing to do with the fact that i just used MODTRAN. The whole concept of CO2-sensitivity is based on effect from each doubling to be similar – incl and excl feedbacks.
– So if you are correct about MODTRAN not using feedback – what would that change?
K.R. Frank
Certainly, Hansen wouldn’t have written, “9,25.”
I’m afraid my poor little brain cell cannot follow the logic of this article. And I work in a scientific field so I don’t know what non-scientific people will make of it.
Richard Telford, you write:
”
Please also remember that the total greenhouse effect of 33K is for a planet with an albedo of ~0.3. If you removed all greenhouse gases the temperature would be 33K colder, but once ice feedback occur, the albedo would increase, and the temperature would fall even further.
”
This thinking is super relevant. My comments though:
the 33K goes for a globe with todays albedo. So the atmosphere including greenhouse gasses today are eeping this Eath with its appearance 33K warmer. This tells something about the greenhouse gas effects. If you then cooled earth down, we would due to ice mostly see a cooling greater than 33K.
But we have to seperate things: The 33K shows what the gasses themselves “can do” without help from albedo changes etc.
So far so good.
But Hansens 6 K per doubling of CO2 is not much helped by ice changes, as the Earth already has rather small icecaps. The overall albedo of earth due to ice changes wont change that much due to a warming. And therefore the most important albedo effect, ice , cannot really help much in a situation of warming.
But still hansen believes that just one CO2 doubling should cause a temperature change in same magnitude as the temperature difference over the iceages.
So buttom line: 33 K is the warming effect of the atmosphere today, not much albedo change can be expected from warming up.
(Hansen believes that each single CO2 doubling shold cause temperature changes in the same size as the temperature over the ice ages due to the feedbacks.)
K.R. Frank
It’s difficult to follow the article. If I understand correctly, the author is missing the moisture feedback argument. The rest of the warming is alleged to come from moisture feedback. IOW, the CO2 itself causes a fractional amount with cloud formation causing the rest.
The cloud formation is the unknown factor. Spencers recent paper on cloud sensitivity should be a headline here imo, it’s far more powerful than the hockey stick paper highlighted recently. Two papers this year have been more damaging to the extremist AGW case than any I’ve read, MMH10 and Spencers recent work.
MMH show models running 2 to4 times warmer than the measured data and S10 showed that current satellite data predicts a negative feedback to clouds while model data run through the same methods predicts positive feedback.
In the case of this article, extremist AGW predicts that the CO2 does a bit of work and the clouds react by warming more. The current data on feedback (which we never had before) shows otherwise. It’s a really big deal but it may need blogland to highlight it further because it looks like climatology is going to try and ignore these gaping holes which hit the core of their argument.
Thanks Frank,
There is too many straight lines in the Modtran output. This indicates it is based on artificial formulae rather than physical measurement simulations.
————-
Hansen’s 6C sensitivity is a long, long-term equilibrium that could take up to 1,500 years. He is stil using 3.0C per doubling in the short-term, year 2100 timeline.
The long-term equilibrium includes feedbacks from water vapour, the deep oceans fully adjusting, glacial melt which can take a long time given the thermal inertia of the ice, and even vegetation patterns moving toward the poles – forests growing into tundra locations for example.
It is just that throughout the history of the planet, there was always enough time for the long, long-term equilbrium to set in and we do not find 6C sensitivity in the climate history, maybe 1.0C to 1.5C.
How good is the theory correlating CO2 with warming? My point is that it all seeems to be based on computer modeling that, at it’s core assumes a certain warming effect from CO2 (and other factors). If the CO2=warming theory is wrong (like warming causes CO2 increases in the atmosphere, not the other way around), then we have GI-GO in the models….right?
Just askin’.
Jeff, you write:
”
If I understand correctly, the author is missing the moisture feedback argument. The rest of the warming is alleged to come from moisture feedback. IOW, the CO2 itself causes a fractional amount with cloud formation causing the rest.
”
Thanks Jeff for comment. In fact I did not focus on where and how the claimed big CO2-sensitivity comes from (allthough thats interesting too, cant beat them all)
In stead i focus on the very buttom line: What happens if we just accept the huge estimates of CO2 warming from each doubling? Then for example the just 3 CO2 doublings incl feedback (using Hansens 6 K) should result in a temperature increase 3 times larger than the difference between ice ages and interglacials ? etcetc.
Bill!, Thanks for comment!
Its true, many inputs to science concerning CO2 effect are actually just smaller changes over thousands years, and the CO2 effect to occur within year 2100 appears not well supported in actual data from the ice cores or the like.
K.R. Frank
K.R. Frank
“So if you are correct about MODTRAN not using feedback – what would that change?”
Everything.
It causes you to make at least two errors, I just want to focus on one of them:
Your argument is predicated on the temperature change is all greenhouse gases were removed being 33k. This is only valid if the albedo is fixed. Since snow and ice cover would increase if the temperature was 33k colder, the albedo would increase, the temperature would drop further. You now need to compare the forcing from a doubling of CO2 with value larger than 33k – the effect of greenhouse gases with ice albedo feedbacks.
Jeff, you write:
“In the case of this article, extremist AGW predicts that the CO2 does a bit of work and the clouds react by warming more.”
Check this: Are we sure that there is even more water in the atmosphere after 1948? No, so how can anyone claim positive feedbacks??
IPCC WATER GATE:
http://hidethedecline.eu/pages/posts/feedback-positive-ndash-rdquowhat-makes-co2-heat-dangerousrdquo-29.php
K.R. Frank
“As the total warming effect of all greenhouse gasses is assumed to have a warming effect of approx 33 K…”
This fundamental misunderstanding renders your conclusions invalid. Greenhouse gases would actually warm the surface a lot more than that, if it were not for convective cooling.
Frank
From what point are we measuring a (mythical) potential increase of say 3C degrees?
Let us assume that CO2 levels didn’t change during the depths of the LIA 1650-1698 .
(which surely is strange if it is supposed to be a climate driver- see graph 1)
http://noconsensus.wordpress.com/2010/03/06/historic-variations-in-co2-measurements/
Surely a doubling of CO2 from 270ppm should result in a 3C temperature rise that is measured from 1698-which is when a warming trend started? Why are we taking it from Hansen’s 1880 Giss records which merely plugged into the end of an already well established warming trend which had commenced nearly 200 years previously?
(I am temporarily suspending my incredulity in the merits of the highly dubious notion of an accurate ‘global’ temperature in the first place)
tonyb
I find the article very difficult to follow from a “technical writing form” aspect. The many convention errors are jarring and decreases the overall quality of the science. In the blogosphere as well as in paper journals, conventions count as much as the science does.
Darn WUWT, all these people discussing and commenting like grown ups, shouldn’t there be more name calling and unsubstantiated fact flinging at this rate people might come to a consensus.
And anyone that is trying to show the UN’s IPCC as a bunch of monkeys with the keys to the computer suite is thumbs up in my book.
There is more involved in Hansen’s 3C long term climate sensitivity then just ice albedo. You also have things like co2 and methane release and trees gowing further north. You don’t see the 3C long term climate sensitivity batted about too much. I suspect the reason is you don’t have to be a climate scientist to grab on to the most logical question: if there is a high long term climate sensitivity then how much of today’s warming can be explained by the long term sensitivity from forcings in the past? Not a question one would wish to answer when you are already missing heat from recent forcings.
richard telford says:
September 8, 2010 at 5:49 am
Sorry Richard, you can’t remove all greenhouse gases and then state that snow and ice would change the albedo – you removed all greenhouse gases, remember. We either have greenhouse gases (water included) or we don’t. If we have water, then we can have ice, snow, clouds, if not, then see the other, effectively waterless planets like Mars.
[Matt, water has been found on Mars.]
I agree with Jeff Id. MMh10 and Spencer clearly have inflicted mortal damage to CAGW.
CAWarmers always talk about feedbacks and such, but apparently haven’t read either paper or just wish they’d go away, but they can’t be ignored forever and should be kept in the spotlight. The data show negative feedbacks dominate in nature as it always has. Spencer made a public plea for all scientists to debunk his paper. For the sake of science, they should respond.
http://www.drroyspencer.com/2010/09/one-the-debunking-spencers-feedback-ideas-an-appeal-to-physical-scientists-everywhere/
The hockey stick has been shattered how many times now? People know the h/s was and still is a complete fraud. Bury the zombie under Giant stadium and be done with it. If h/s worshipers need to build a shrine to mourn their loss, whatever, it’s dead. Get over it.
Models! I, recently, tried to encase a damaged (Thanks to me not clearing this stuff away from kids) Airfix model in resin. The results were worse than I expected. The temperature of the chemical reaction and the fact I was impatient, the busted plastic model, well, was melted in the resin, permanently! LOL
Just watched a program on ABC here in Aus tonight, and while we’re worrying about CO2 being a “pollutant” (Emissions from concrete, wine, bread, beer….pollutants?), we have people in this world suffering “noma”, the billons “spent” on “renewables” could be spent, wisely, on real issues.
I guess a poor person on Africa, is, well, worthless.
I like the gist of the article but I think it is a bit more hand waving than the maths would imply. The problem is that the percentage of forcing due to CO2 (as against the other greenhouse gases and convection) is not likely to be constant for every doubling of CO2. For example if there were no CO2 at all the world would be amost entirely frozen since the level of water vapour in atmosphere would be very low and therefore almost all radiation from the surface would go directly into space.
Introducing some CO2 would therefore have a major impact with strong positive feedback as water evaporated. This might even increase with say the second third and fourth doubling as the more powerful water vapour effect began to dominate. In later doublings the effect of increasing water vapour might very well be a strong negative feedback once clouds become possible (reducing incoming radiation) and convection increases the heat loss to the upper atmosphere. At some point this negative feedback might turn positive once more if there were some natural limitation on cloud formation or convection losses. My guess is that no one really knows what the nett feedbacks are today and certainly do not know what they will be in the future.
Therefore it is not possible to use the “CO2 is 15% of the warming effect” which exists today for any scenario in the past or the future. However, Mike’s article makes the strong point that the IPCC are saying that the next doubling with feedback will be far more than the average historic temperature increase for a CO2 doubling. It is not impossible, given the uncertainties of the feedbacks of the past, but extraordinary claims demand extraorinary evidence. I have not seen it!
Mike Haseler wrote
Air heated at the surface rises by convective currents, and then is cooled by IR emission into space. The addition of CO2 to this warm air mass increases the rate of cooling thereby increasing the rate of cooling of the atmosphere.
I have sympathy with your idea and have made the same point myself but it is only part of the picture. You cannot counter the oversimplification of AGW with an oversimplifying of your own.
The upper atmosphere is heated by radiative absortion (mainly by H20 and CO2 molecules) as well as convection. This heat is radiated into space (mainly by H20 and CO2 molecules). The amount of heat radiated is determined by the number of molecules and the temperature of those molecules. As the concentration of H2O and CO2 increases the meanfree path of photons decreases and the average height at which radiation to space takes place increases. In principle the higher one goes the cooler it is so the radiation amount drops. The AGW argument is that since radiation is proportional to the fourth power of abolute temperature the height change dominates the density change and there is a nett reduction in outgoing radiation. Less outgoing radiation from the upper atmosphere means the surface has to warm to maintain the radiative balance.
So your simple argument may persuade the layman but would not influence the AGW atmospheric scientist. The stronger argument I believe is whether the change in height will really lead to a reduction in temperature. As I have stated before the Hadley explantation states that the effective radiation level into space occurs at a point in the troposphere where the 6K per kilometre adiabatic lapse rate still holds. However all the data I have seen suggests that the level at which CO2 emits is very near, if not in, the tropopause where there is no change in temperature with height. In this situation your simple argument becomes true. But to prove it you would have also have to prove that there is no change to the height of the tropopause. A few years ago there were reports that an increase in the height (and therefore a drop in temperature) had indeed been measured but it was then quickly refuted. I have heard nothing since so perhaps the jury is still out.
Frank Kotler says:
September 8, 2010 at 2:15 am
“You’ve started way too high! Start with one molecule of CO2. Double it until you get to a single mole. Already – even if we assume CO2 is responsible for 100% of the 33k warming – a half degree per doubling is too high!”
================
I like that. Sometimes my mind comes up with questions that I discard and decide not to ask, because I assume they must be too innocent. Questions like the following:
If the doubling effect on forcing is logarithmic, with the first 30 ppmv or so (that is, about 5 doublings starting at 1 ppm) accounting for a disproportionately large part of the current warming effect of CO2, then why are there so many initial doublings that have no effect whatsoever? This must be so because there is a huge number of doublings from 1 molecule to current levels.
How do you determine the minimum initial concentration whose doubling will follow the current theoretical assumptions of climate sensitivity, whatever they are?
In other words, how many doublings does it take for these doublings to start becoming relevant? (i.e: how many initial doublings would have no measurable effect?)
And I always end up with the same question:
Why are there no attempts ever made to measure the warming effect of different concentrations of this gas under some kind of controled conditions? Why must everything remain forever floating in theoretical ether?
Regressing all the way back to one molecule makes no sense. The problem is as follows. The radiation calculations involve an assumption of local thermodynamic equilibrium (LTE). Gas concentration must be above some threshold for LTE to apply. One molecule is surely not enough, and LTE does not apply to the upper atmosphere. There is some doubt that LTE even applies to Earth’s present troposphere, and even stellar atmosphere physicists disagree about the applicability of LTE to an atmosphere as dense as the photosphere for purposes of calculating spectral line shape. This is why I have asked on several occasions whether anyone knows of actual measurements to verify MODTRAN calculations. Does anyone know about such?
At any rate the author here assumes 5ppm as a starting point, and the distance from 5 to 320ppm is six doubles for sure, but we aren’t certain if LTE applies anywhere along this chain.
The Stefan Law holds true only if the entire spectrum is present in the emission. On Earth the transmission passes though “windows” in the spectrum, and the result is that the surface temperature relationship is more like T to the 4.6 power, with a proportional constant smaller than the Stefan constant (5.67e-8). One the other hand, for small changes in temperature one can use a linear proportionality in any case–Taylor Series and all that.
berniel says:
September 8, 2010 at 3:15 am
The Climate sensitivity wiki article you refer to says…
‘CO2 climate sensitivity has a component directly due to radiative forcing by CO2 (or any other change in Earth’s radiative balance), and a further contribution arising from feedbacks, positive and negative. Without any feedbacks, a doubling of CO2 (which amounts to a forcing of 3.7 W/m2) would result in 1°C global warming, which is easy to calculate and is undisputed. The remaining uncertainty is due entirely to feedbacks in the system, namely, the water vapor feedback, the ice-albedo feedback, the cloud feedback, and the lapse rate feedback’; addition of these feedbacks leads to a value of approximately 3 °C.
As a non-scientist, I have always followed Lindzen that the dispute is about the feedback component of sensitivity.”
It is looking more and more like the total additional feedback mechanisms are negative rather than positive. Ice albedo has only a small effect during climate optimums as the distribution of the relatively small amount of ice is at the poles were the angle of incidence low, and even sea water reflects much of the incoming light at these latitudes.
It is now looking like cloud cover increases with temperature, and is a negative climate feedback mechanism.
Water vapour is a significant ‘greenhouse’ gas, but it already exists in the atmosphere in large quantities, with its absorption spectrum already well saturated. Further water vapour will have little further effect on temperature.
My view is that the climate oscillations we observe are due to the deterministic chaos inherent in its weather systems. As the Earth heats, the oceans and the atmosphere become more turbulent dissipating heat more efficiently, with the reverse happening when the planet cools. Ice ages are ‘black swan’ events which occur when a series of cooling events coincide, these kick the Earth into a stable cold phase.