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
The first step is to show that we can in fact double the CO2 in the atmosphere from 390 to 780. I have read several places that say burning all the known reserves of gas and oil cannot do it. Burning all the coal, gas and oil just makes it, but how long will it take to burn all of them.
If we cannot get to a double then lets say so.
The model output is obviously flawed. There’s no way in hell the slope could be constant from 5ppm to 325ppm. There’s something out of whack in the model that produces sudden slope changes.
Nevermind. I see the problem. It’s in the x-axis scaling which deviates from exponential below 5ppm and above 320ppm. It would be less misleading and more informative if the x-axis was uniformly exponential or uniformly linear.
Frank Lansner says:
September 8, 2010 at 5:53 am
Check this: Are we sure that there is even more water in the atmosphere after 1948? No, so how can anyone claim positive feedbacks??
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Now you have reached the crux of mainstream climate science. It’s not about the little bit of warming which you have demonstrated CO2 causes, it’s about the response.
I suggest you put your new question to Real Climate and see if Gavin takes flight from the arm waiving. A trip to Roy Spencers blog for his recent paper and discussion and you may turn into a full blown skeptic.
It’s only been recently that we’ve had the ability to measure cloud response in a reasoanble fashion, Dr. Spencer says all the recent satellite evidence he can find all points to negative feedback from cloud vapor (i.e. even less warming than CO2 by iteself) while all the models are loaded with positive feedback.
If he’s right the models would overshoot temps substantially, which they do by MMH10. A paper vigorously blocked by the climate community.
Everyone admits though that the sat data isn’t long enough to make a conclusion, but without strong positive feedback, there is no dangerous warming.
Mike Haseler says:
September 8, 2010 at 12:35 am
“QED too much CO2 will cause atmospheric cooling”
That’s an interesting hypothesis. Milankovich cycles are generally blamed for ending interglacial periods but as warming proceeds during the interglacial CO2 level rises as the warming global ocean releases dissolved CO2. It would be a real laugh riot if the so-called “tipping point” in regard to atmospheric CO2 is runaway cooling instead of runaway warming.
Richard Telford, I still do understand your relevant point concerning ice and albedo, but i already answered this in
“Frank Lansner says:
September 8, 2010 at 5:23 am ”
I cant see that you understood what I asnwered 🙂
tonyb says:
“From what point are we measuring a (mythical) potential increase of say 3C degrees? ”
Hi Tony!! CO2 sensitivity is related to doublings in general as definition. (However as many points out – the effects from CO2 in all kinds of feedbacks can be different)
cal says:
September 8, 2010 at 6:43 am
“Introducing some CO2 would therefore have a major impact with strong positive feedback as water evaporated. ”
Maybe so, but where is the extra water in the atmosphere since 1948?
http://hidethedecline.eu/pages/posts/feedback-positive-ndash-rdquowhat-makes-co2-heat-dangerousrdquo-29.php
K.R. Frank
Mike Haseler says:
September 8, 2010 at 12:35 am
“CO2 is not only a warming gas, the same physical properties make it a cooling gas where the CO2 is warmer than a heat sink like outer space. It helps radiate IR from the convective cooling cycle into space, and the higher the level of CO2 the more effective the cooling cycle. QED too much CO2 will cause atmospheric cooling”
I have been looking for a diagram which shows this CO2 cooling effect. That is, a diagram like the familiar breakdown of sun radiation energy into components which are reflected/absorbed/transformed between atmosphere, clouds, and earth’s surface, but doing this for night-time. The daytime ‘forcing’ of CO2 would be shown as a night-time ‘reducing’.
This would be instructive and also publicise the cooling counterpart of the oft quoted sunlight radiative balance diagram. In this way CO2 would be seen correctly as both a warming and a cooling agent, helping to offset the fixed view of CO2 as a warmer-only.
Mike Haseler says:
September 8, 2010 at 3:59 am
…
That is why, whenever I am able, I mention the cooling effect of CO2 because this destroys this simple message…
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Right on the mark. But the arm waving stops quicker if one applies the tourniquet at the neck (funding). It was never about science.
Tenuc says:
September 8, 2010 at 7:39 am
“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 might not be quite so small. Snow is highly reflective and in the winter it reflects a lot of incoming shortwave over temperate land masses. Just a little bit colder can greatly increase the extent and duration of winter snow cover and it’s a positive feedback which, judging by the paleo-record is wicked fast at bringing interglacial periods to an end. By the same token just a little bit colder can greatly reduce the extent and duration of growing seasons (number of days between killing frosts). Any amount of global cooling is a bad thing. We really need the warming to continue for the sake of agriculture but unfortunately that’s probably not in the cards. Hopefully technology (I’m betting on genetic engineering boosting agricultural output) will come to the rescue when the warming turns to cooling.
Frank,
As a old modtran user ( when it used to be classified) you need to understand that it does not include feedbacks. You can use it to tell you one thing: More C02 = More warming, all things be equal, ie no feedbacks. There is no way of calculating sensitivity. Sensitivity can only be estimated by running a GCM. For engineers we might use Modtran to estimate what level of IR signal we can expect to get when radiation passes through the atmosphere, for example. So if we have a heat source on the ground emitting and we want to view it from above we have to calculate how much of that signal will will actually reach the sensor and how much of it will be blocked by the atmosphere. Or, if we are on the ground and want to estimate what a hot source in the sky will look like by the time that signal passes down through the atmosphere we can also use MODTRAN. As the model shows, adding C02 to the atmosphere will result in changes to the transfer of radiation. If the model wasnt right, if C02 did not interact with IR the way the model describes the sensors in space, the sensors on the ground would not perform as they do. What MODTRAN tells us is that all things being equal a worl with more C02 is a warmer world. Not a colder world, not a world with the same temperature, a warmer world. Folk who deny that C02 has any effect on the transfer of radiation through the atmosphere, need to understand that the fundamental science, engineering and working devices say otherwise.
How much warming when we INCLUDE feedbacks? that’s the real question.
Francisco, you write
“How do you determine the minimum initial concentration whose doubling will follow the current theoretical assumptions of climate sensitivity, whatever they are?”
BINGO a very very very central question!
Never mind what, there will allways be a number of doublings with similar CO2 effect, and thus it not at all due to my using MODTRAN with or without feedbacks that we can wonder how these doublings each with HUGE supposed warming can occur.
But why not talk about 1000.0000 doublings then?
The “first” CO2 molecules added to a gas will not cover the radiation from other CO2 molecules. Therefore in very low concentraions CO2 effect is simply proportional to the amount. Two molecule has twice the effect of one. But at some point the shadowing starts to dominate and we get a logarithmic curve where each doubling yields same effect.
MODTRAN shows that the doubling effect can be used at least from 5 ppm as i did.
Eventually a model like MODTRAN must have its fundamental data from experiments.
K.R., Frank
Solar insolation considered at the equator vertically, is about 1366 W/m2, of which 275 W/m2 is absorbed in the atmosphere (not reflected, refracted or transmitted) and 680 W/m2 reaches the surface, is absorbed and later is reemitted as heat/IR. That is a total of 955 W/m2. As the earth’s surface is 4X its cross-sectional capture area, the average incoming solar power warming the planet at any time is 238 W/m2. This is the amount that gives us the 33C* greenhouse gas warming even the IPCC says. The greenhouse warming is NOT linearly related to gas concentration, but decreases with concentration. Another agreement of warmists and skeptics. But if it were, the relationship is 7.21 W/m2 per C* for all of the GHGs.
A Hansen-predicted 3 – 6C* rise in temperature by this measure would require a 22 – 43 W/m2 forcing factor at the 7.21 W/m2C* average historical rate. Yet if CO2 is responsible for only 15% of greenhouse warming to-date, then we can say also that of the average 7.21 W/m2C* the total GHG represent, then only 1.08 W/m2 radiative forcing is CO2 based, i.e. for 3-6C*, the forcing needed is 3.24-6.5 W/m2. This INCLUDES the feedback mechanism of H2O, whatever it is.
At each step of my journey looking into CAGW I bump into such back-of-the-envelope calculations that make the IPCC claim bizarre. I have learned in my decades as a professional geoscientist that if you cannot sketch out the result with a pencil and a hand calculator and be satisfied with the general result, the claim you’re checking is false – false, generally, because of either optimism or pessimism.
The finicky details are never close to the general whole, except in an unstable system. Hollywood notwithstanding, Planet Earth is not unstable, and requires huge asteroids or global basaltic flows to seriously change conditions overnight. The USS Vincennes shot down an Iranian 747 after the computer systems misidentified it as an attacking F-14 principally because no one was on the bridge with a pair of binoculars to see that the sacrosanct computers were misleading them with misinformation. The CAGW is another Vincennes in action: reasonable men and women with binoculars (or pencils and a piece of paper) asking whether, in principle, the sensitivity to pCO2 makes sense, would shut down Gore, Suzuki and the IPCC.
I cannot understand how we have lost the concept of reasonablness and swallowed whole the shriek of the raging elite after a recent history of Presidents (corporate and national), wars, economies and personal scandals that has shown us by painful means that the extremes we are told will hurt us/will not hurt us are never, and I mean never, real.
Hi Jeff !
Yep, the water is a hot potato
http://hidethedecline.eu/pages/posts/feedback-positive-ndash-rdquowhat-makes-co2-heat-dangerousrdquo-29.php
I think it should be called the IPCC water gate 🙂
The thing is: Why dont IPCC CONSTANTLY everywhere show the latest numbers of water content in the atmosphere?
???
If they where actually so sure that greenhouse effect is so massive, its really odd that they just cherry pick the little brother CO2 and seems to forget about water.
In the article above i show the water content in different atmosphere layers, and there is indeed NO increase, if anything a decrease. And this decrease shold obviously be part of all considderations of the claimed warming from greenhouse gases.
Thanks for commenting
K.R. Frank
“Folk who deny that C02 has any effect on the transfer of radiation through the atmosphere, need to understand that the fundamental science, engineering and working devices say otherwise”
Folks who design and build heat pumps (most often for refrigeration) know better, Mr. Mosher. If it’s static, as the models and the idee fixee, it is not realistic. That is to say it is unreal and does not correspond with reality. That is to say to represent it as reality is insane. Insane, Mr. Mosher. Certifiably.
Are you telling me that this is a planet without much ice?
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/ARCHIVE/20080321.jpg
Steven Mosher , thanks for comment!
I know the chaos of feedbacks etc only too well, but still i find it relevant to use rough bird perspective just to get a tiny clue on the bigger picture.
In some comments on the blog here, i get the feeling that people do not really accept that each CO2 doubling has rougly same effect. It is as though some accepts that for some reason, just exactly the effect of CO2 in our days, “the present doubling” would have a much much greater effecter than all other doublings… This to “rescue” the idea that the present doubling would be very very dangerous without violating the mathematics.
But what are the arguments that CO2-sensitivity in todays level 3-4-500 ppm and todays conditions should warm the Earth much more than other doublings, other conditions?
And where is the documentation for this?
I show, that if all CO2 doublings has same impact – as indicated with the concept of CO2 sensitivity – EACH of them must have a quite small effect – in full agreement with idso and Lindzens results. If the present CO2 doubling can do something the other CO2-doublings could not – well, document it. prove/show that the present CO2-doubling then is extraordinar !
🙂
K.R, Frank
Frank,
The empirical evidence from geology and paleontology demonstrates the changes in atmospheric concentrations of CO2 and global mean temperatures are generally uncorrelated when observed over the geological periods. In other words, changes in CO2 more often than not have no corresponding change in temperatures. The models therefore fail to hindcast the empirical evidence by mammoth proportions in both gains and losses. If the AGW hypotheses and models were true, confounding factors would not be able to account for such mammoth differences between the predictions of their models and the empirical facts observed in the geological samples. No matter whether the sensitivity range is between 1-6 degrees in Kelvin/Celsius, the model results are nonsensical when compared to the actual broad range of conflicting changes recorded in the geological samples.
@Mike Haseler says:
September 8, 2010 at 12:35 am
This is a question akin to the one: “what happens when you double the insulation thickness of double glazing”. In theory, the insulation is proportional to the thickness of air, but the reality is that air doesn’t just sit there and do what the “theory” says.
Just as air in double glazing will start to flow in a convective cycle, so the atmosphere churns in a convective cycle tearing the static model of the atmosphere apart and making it useless to determine the impact of CO2.
– – – – – –
Spot on Mike. Empirical studies by Home Environment researchers have found that the optimal air pocket thickness is about 1 inch in a double glazing, where the R value reaches a maximum. Increase the thickness above that, the overall R value decreases due to an increase in air convection within the pocket, more than offsetting the decrease in heat conduction across the pocket of air due to the increased thickness. How many inches are there in the double glazing we call the earth’s atmosphere?
This seems rather confused. Could you point me to the reference claiming that the radiative forcing of doubling CO2 alone (holding everything else equal) is much greater than 3.7 W/m2 (of roughly 1.1 C warming)?
Also, this paragraph is a bit off:
“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.”
You can’t simply take a number like 15% and apply it to various concentrations, given overlapping absorption bands and whatnot. For example, with less CO2 concentration, you would have a lower water vapor concentration (absolute humidity generally being a function of temperature).
Steven Mosher says: September 8, 2010 at 8:37 am
Frank,
As the model shows, adding C02 to the atmosphere will result in changes to the transfer of radiation. If the model wasnt right, if C02 did not interact with IR the way the model describes the sensors in space, the sensors on the ground would not perform as they do. What MODTRAN tells us is that all things being equal a worl with more C02 is a warmer world. Not a colder world, not a world with the same temperature, a warmer world. Folk who deny that C02 has any effect on the transfer of radiation through the atmosphere, need to understand that the fundamental science, engineering and working devices say otherwise.
How much warming when we INCLUDE feedbacks? that’s the real question.
Mosh,
The graphs above from MODTRAN show two things:
1st graph = Increasing [CO2] from ~320ppm to ~390ppm results in only ~1W/m2 of 1st order forcing,
2nd graph = At ~350ppm [C02], the effect from CO2 is ~ 99% exhausted.
This indicates the earth has warmed ~all it will from 1st order CO2.
Since you are familiar with MODTRAN, and these numbers are correct disregarding 2nd order feedbacks, are you prepared to suggest that any temperature increase in the future as predicted by IPCC will be 99% associated with feedbacks (ie. somewhat synonomous with sensitivity)? If so, then explain why current global temps are lower than predicted by IPCC using a climate sensitivy of 3? (don’t weasel out on this – see previous post and IPCC graph of scenarios) Also, then are you suggesting that the hypothesized feedback effect is temperature dependent? At what temperature do the feedbacks suddenly appear? Should they not increase in a linear fashion?
richard telford says:
September 8, 2010 at 9:02 am
Are you telling me that this is a planet without much ice?
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/ARCHIVE/20080321.jpg
What he’s saying is little ice relative to an ice age or snowball earth. With increasing ice, sea levels drop reducing evaporative surface area. Humidy drops and the greenhouse effect from H20 is reduced. CO2 has miniml impact.
D. Patterson says:
“The empirical evidence from geology and paleontology demonstrates the changes in atmospheric concentrations of CO2 and global mean temperatures are generally uncorrelated when observed over the geological periods.”
Yes! Last week i wrote on exactly that subject on Joanne novas site:
http://joannenova.com.au/2010/08/ice-core-evidence-no-endorsement-of-carbons-major-effect/
Hi Zeke!
You write “Could you point me to the reference claiming that the radiative forcing of doubling CO2 alone (holding everything else equal) is much greater than 3.7 W/m2 (of roughly 1.1 C warming)? ”
Help me out, What did i write that made you ask that?
K.R. Frank
Tenuc says:
September 8, 2010 at 7:39 am
“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.”
I tend to agree on water vapor as a GHG but not water vapor as a heat pump. As temperature increases so does the amount of water vapor the troposphere can hold and so does evaporation rate. In short the water cycle accelerates and with it the transport rate of heat from surface to space. The set temperature seems to be around the dewpoint. More or less cloud cover is not necessary for the themostat to be effective – the extent (and hence global albedo) can remain the same so long as the actual amount of water evaporating from the surface and returning as rainfall increases.
Water in all its phases rules the climate. The primary effect of the atmosphere is simply providing 14.7 psi pressure at the surface which lowers the boiling point of water enough so that a global ocean is possible.
Tim Clark, you write to Richard: “What he’s saying is little ice relative to an ice age or snowball earth.”
Spot on!
We are now in an interglacial and you can claim that there is “much” ice now. Much of what is left (on Antarctica) is rather hard to get rid of as that continent has average temperature of around -27 as I remember, so Ice / snow cover loss on Antarctica and change in albedo right now is not really an option/excuse to explain Hansens HUGE estimate of CO2 sensitivity, 6K.
As I wrote in a comment: I show that if all doublings (9,25!) has same effect, each of these must have limited effect for the mathematics to add up. SO! If the present CO2 doubling for some reason shold have a much greater effect than the other doublings, there must be a specific reason. And an interglacial amount of ice on Antarctica that is not likely to change albedo, that just does not do the trick 🙂
K.R. Frank