Guest post by David Archibald
The greenhouse gasses keep the Earth 30° C warmer than it would otherwise be without them in the atmosphere, so instead of the average surface temperature being -15° C, it is 15° C. Carbon dioxide contributes 10% of the effect so that is 3° C. The pre-industrial level of carbon dioxide in the atmosphere was 280 ppm. So roughly, if the heating effect was a linear relationship, each 100 ppm contributes 1° C. With the atmospheric concentration rising by 2 ppm annually, it would go up by 100 ppm every 50 years and we would all fry as per the IPCC predictions.
But the relationship isn’t linear, it is logarithmic. In 2006, Willis Eschenbach posted this graph on Climate Audit showing the logarithmic heating effect of carbon dioxide relative to atmospheric concentration:
And this graphic of his shows carbon dioxide’s contribution to the whole greenhouse effect:
I recast Willis’ first graph as a bar chart to make the concept easier to understand to the layman:
Lo and behold, the first 20 ppm accounts for over half of the heating effect to the pre-industrial level of 280 ppm, by which time carbon dioxide is tuckered out as a greenhouse gas. One thing to bear in mind is that the atmospheric concentration of CO2 got down to 180 ppm during the glacial periods of the ice age the Earth is currently in (the Holocene is an interglacial in the ice age that started three million years ago).
Plant growth shuts down at 150 ppm, so the Earth was within 30 ppm of disaster. Terrestrial life came close to being wiped out by a lack of CO2 in the atmosphere. If plants were doing climate science instead of us humans, they would have a different opinion about what is a dangerous carbon dioxide level.
Some of the IPCC climate models predict that temperature will rise up to 6° C as a consequence of the doubling of the pre-industrial level of 280 ppm. So let’s add that to the graph above and see what it looks like:
The IPCC models water vapour-driven positive feedback as starting from the pre-industrial level. Somehow the carbon dioxide below the pre-industrial level does not cause this water vapour-driven positive feedback. If their water vapour feedback is a linear relationship with carbon dioxide, then we should have seen over 2° C of warming by now. We are told that the Earth warmed by 0.7° C over the 20th Century. Where I live – Perth, Western Australia – missed out on a lot of that warming.
Nothing happened up to the Great Pacific Climate Shift of 1976, which gave us a 0.4° warming, and it has been flat for the last four decades.
Let’s see what the IPCC model warming looks like when it is plotted as a cumulative bar graph:
The natural heating effect of carbon dioxide is the blue bars and the IPCC projected anthropogenic effect is the red bars. Each 20 ppm increment above 280 ppm provides about 0.03° C of naturally occurring warming and 0.43° C of anthropogenic warming. That is a multiplier effect of over thirteen times. This is the leap of faith required to believe in global warming.
The whole AGW belief system is based upon positive water vapour feedback starting from the pre-industrial level of 280 ppm and not before. To paraphrase George Orwell, anthropogenic carbon dioxide molecules are more equal than the naturally occurring ones. Much, much more equal.
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Willis Eschenbach (23:44:44) :
For an example from another discipline, consider the temperature of the human body. It is very insensitive to the environmental temperature. When the forcing from the environment goes up or down, the human body temperature barely responds.
But when we get a fever, our temperature can spike radically. All the human body’s lack of sensitivity to forcing shows is that human temperature is not set by the forcing … but that doesn’t mean it can’t change as you claim.
Yes, Willis you picked an example of an organism which has a control mechanism to maintain body temperature, a better example would be a lizard, the which body temperature of which follows the surrounding temperature! Also it’s not true that the ‘human body temperature doesn’t respond’, try sitting out in the snow or out in the sahara desert naked.
Phil. (18:51:39)
First, I’m obviously talking about the core body temperature, so it is ingenuous to suggest sitting out in the snow or the desert. Within obvious limits, neither of these change the core temperature.
Second, you assume that the climate has no mechanism to maintain the temperature. This is a very doubtful assumption, as all flow systems which are far from equilibrium have such a mechanism that regulates certain aspects of their behavior. For the climate, this mechanism maximizes the total of work done and turbulent heat loss.
See my posts here and here, and Bejan’s work here among others, for more information on this question.
ABG (06:37:28)
All that is very fine … but you have only claimed that we have evidence that the long-term temperature of the earth is ruled by the forcings. Until you produce some, all we have is your word that it exists.
Despite changing locations of the continents, despite strikes by huge meteors, despite millennia long volcanic eruptions, the earth’s temperature has not varied by more than ± 3% in the last half billion years. I call that “stable”. If you can design a system as complex as the climate that has that characteristic, and which does not have some kind of temperature regulating mechanism, I’d love to see it. I propose such a mechanism here …
Henry@ABG
I started my own investigations on global warming in October last year and I already compiled my final report. If you are interested in reading this, here are the results of my investigations/conlusions:
FOR MY CHILDREN, & FAMILY AND FRIENDS LIVING IN THE NORTHERN HEMISPHERE
You may not know this. For a hobby I did an investigation to determine whether or not your carbon footprint, i.e. carbon dioxide (CO2), is really to blame for global warming, as claimed by the UN, IPCC and many media networks. I guess I felt a bit guilty after watching “An inconvenient truth” by Al Gore, so I had to make sure for myself about the science of it all. If you scroll down to my earlier e-mails you will note that I determined that, as a chemist, I could not find any convincing evidence from tests proving to me that CO2 is indeed a major cause for global warming. As my investigations continued, I have now come to a point where I doubt that global warming is at all possible…. Namely, common sense tells me that as the sun heats the water of the oceans and the temperatures rise, there must be some sort of a mechanism that switches the water-cooling system of earth on, if it gets too hot. Follow my thinking on these easy steps:
1) the higher the temp. of the oceans, the more water vapor rises to the atmosphere,
2) the more water vapor rises from the oceans, the more difference in air pressure, the more wind starts blowing
3) the more wind & warmth, the more evaporation of water (evaporation increasing by many times due to the wind factor),
4) the more evaporation of water the more humidity in the air (atmosphere)
5) the higher the humidity in the air the more clouds can be formed
6) Svensmark’s theory: the more galactic cosmic rays (GCR), the more clouds are formed (if the humidity is available)
7) the more clouds appear, the more rain and snow and cooler weather,
8) the more clouds and overcast conditions, the more radiation from the sun is deflected from the earth,
9) The more radiation is deflected from earth, the cooler it gets.
10) This cooling puts a brake on the amount water vapor being produced. So now it is back to 1) and waiting for heat to start same cycle again…
Now when I first considered this, I stood in amazement again. I remember thinking of the words in Isaiah 40:12-26.
I have been in many factories that have big (water) cooling plants, but I realised that earth itself is a water cooling plant on a scale that you just cannot imagine. I also thought that my idea of seeing earth as a giant (water) cooling plant with a built-in thermostat must be pretty original….
But it was only soon after that I stumbled on a paper from someone on WUWT who had already been there, done that …. well, God bless him for that!
i.e. if you want to prove a point, you always do need at least two witnesses!
Look here (if you have the time):
http://wattsupwiththat.com/2009/06/14/the-thermostat-hypothesis/
But note my step 6. The Svensmark theory holds that galactic cosmic rays (GCR) initiate cloud formation. I have not seen this, but apparently this has been proven in laboratory conditions. So the only real variability in global temperature is most likely to be caused by the amount of GCR reaching earth. In turn, this depends on the activity of the sun, i.e. the extent of the solar magnetic field exerted by the sun on the planetary system. We are now coming out of a period where this field was bigger and more GCR was bent away from earth (this is what we, skeptics, say really caused “global warming”, mostly).
But apparently now the solar geomagnetic field is heading for an all time low.
Look here:
http://wattsupwiththat.com/2010/01/07/suns-magnetic-index-reaches-unprecedent-low-only-zero-could-be-lower-in-a-month-when-sunspots-became-more-active/
Note that in the first graph, if you look at the smoothed monthly values, there was a tipping point in 2003 (light blue line). I cannot ignore the significance of this. I noted similar tipping points elsewhere round about that same time, (e.g. in earth’s albedo, going up). From 2003 the solar magnetic field has been going down. To me it seems for sure that we are now heading for a period of more cloudiness and hence a period of global cooling. If you look at the 3rd graph, it is likely that there wil be no sun spots visible by 2015. This is confirmed by the paper on global cooling by Easterbrook:
http://wattsupwiththat.com/2008/12/29/don-easterbrooks-agu-paper-on-potential-global-cooling/
In the 2nd graph of his presentation, Easterbrook projects global cooling into the future. These are the three lines that follow from the last warm period. If the cooling follows the top line we don’t have much to worry about and the weather will be similar to what we had in the previous (warm) period. However, indications are already that we have started following the trend of the 2nd line, i.e. cooling based on the 1880-1915 cooling. In that case it will be the coldest from 2015 to 2020 and the climate will be comparable to what it was in the fifties and sixties. I survived that time, so I guess we all will be fine, if this is the right trendline.
Note that with the third line, the projection stops somewhere after 2020. So if things go that way, we don’t know where it will end. Unfortunately, earth does not have a heater with a thermostat that switches on if it gets too cold. Too much ice and snow causes more sunlight to be reflected from earth. Hence, the trap is set. This is known as the ice age trap. This is why the natural state of earth is that of being covered with snow and ice. This paper was a real eye opener for me:
http://wattsupwiththat.com/2009/12/09/hockey-stick-observed-in-noaa-ice-core-data
However, man is resourceful and may find ways around this problem if we do start falling into a little ice age again. As long as we are not ignorant and listen to the so-called climate scientists whose agenda’s depend on money. A green agenda is still useless if it has the wrong items on…
Obviously: As Easterbrook notes, global cooling is much more disastrous than global warming….
Willis Eschenbach (01:26:04) :
First, I’m obviously talking about the core body temperature, so it is ingenuous to suggest sitting out in the snow or the desert. Within obvious limits, neither of these change the core temperature.
I think you mean ‘disingenuous’ and in any case you’re wrong, either of those situations will drop/raise the core temperature and kill you! The human body’s mechanism is to balance heat release with heat loss and uses heat loss coefficient changes to do so in extreme conditions (shivering/sweating), those only have a small range of effectiveness. The whole comfort zone is governed by the shape of the heat release curve which gives a small region of relatively stable temperature with changing heat loss otherwise you’re in trouble!
Second, you assume that the climate has no mechanism to maintain the temperature. This is a very doubtful assumption, as all flow systems which are far from equilibrium have such a mechanism that regulates certain aspects of their behavior. For the climate, this mechanism maximizes the total of work done and turbulent heat loss.
The mechanism is known as the greenhouse effect, same as the human body, loss=release.
Henry@Phil
So how much cooling and how much warming did you say is caused by the CO2?
(exact results would be preferred)
RE: Willis Eschenbach; 9 Mar 2009 (22:09:28) : “…you can do this easily using the MODTRAN line-by-line online radiation calculator.”
I have investigated this results provided by this tool for the default tropical clear air calculation using 293 W/m2 (292.993) for the nominal required output energy flow at 70 km, Iout. I based this flow requirement on a listed maximum lunar surface temperature. I have tried this with CO2 concentration inputs from 0 to over 70,000 ppm, usually in half doubling (1.41421…) steps relative to the nominal pre-industrial concentration of 280 ppm.
I am accepting the results provided as-is. I have no documentation on the use of this tool so I do not know how valid my results are over the full range of CO2 concentrations I tried. I ran this in an attempt to obtain an estimate of the raw CO2 sensitivity of the atmosphere before any positive or negative feedback effects are get involved.
My results with MODTRAN indicate that a constant nominal log-doubling slope of 0.9 deg C per doubling applies over a range of 70 ppm to 792 ppm, but from 4,480 ppm to 71,680 ppm the slope rapidly rises from 1.2 to 2.9 deg C per doubling. I calculated the slope from a precision (low residual error) polynomial approximation of the MODTRAN surface temperature results where the output energy flow at 70 km is required to be 292.993 W/m2.
I do not know if the swift slope increase above 4,480 ppm (over 10 times our current level) is due to a MODTRAN model calculation limitation or if this just shows the spectrum data noise floor becoming significant at these CO2 concentrations. Of course, this could also be showing the actual onset of atmospheric window pinch-off.
Tropical, Clear Air Default Setting Atm Log2 Gnd Tmp Surface Surface Log2 CO2 (CO2/280) Offset Tmp °K Tmp °C Slope 70 -2.0 -0.81 298.89 26.7 0.9 99 -1.5 -0.365 299.34 27.2 0.9 140 -1.0 0.08 299.78 27.6 0.9 198 -0.5 0.52 300.22 28.1 0.9 280 0.0 0.96 300.67 28.5 0.9 396 0.5 1.41 301.11 29.0 0.9 560 1.0 1.86 301.56 29.4 0.9 792 1.5 2.33 302.03 29.9 0.9 1,120 2.0 2.81 302.51 30.4 1.0 1,584 2.5 3.31 303.01 30.9 1.0 2,240 3.0 3.835 303.54 31.4 1.1 3,168 3.5 4.39 304.09 31.9 1.1 4,480 4.0 4.99 304.69 32.5 1.2 6,336 4.5 5.63 305.33 33.2 1.3 8,960 5.0 6.34 306.04 33.9 1.5 12,671 5.5 7.11 306.81 34.7 1.6 17,920 6.0 7.97 307.67 35.5 1.8 25,343 6.5 8.94 308.64 36.5 2.1 35,840 7.0 10.03 309.73 37.6 2.3 50,685 7.5 11.26 310.96 38.8 2.6 71,680 8.0 12.65 312.35 40.2 2.9Swift slope increase? I think not. The rate per doubling is increasing very slowly; the 35840 – 71680 temp offset step is 2.65, and the 2240 – 4480 step was 1.16. On a linear basis, the increase is falling off rapidly. The lower level is 0.516°C per 1000 ppm; the higher level is 0.074°C per 1000 ppm.
David;
By the way, on your charts and in the text, you might want to reconsider the “accepted” pre-industrial number. See here: http://www.canadafreepress.com/index.php/article/18343 / http://www.canadafreepress.com/images/uploads/ball122809-1.jpg .
The actual average (with a HUGE variance range) was probably about 50 higher than the one given, around 335 ppm. Really changes how all those graph slopes look, doesn’t it?
Just For Reference:
After trying out various relationships with the MODTRAN data, I find that if one defines the variable Z=0.979 + 0.911*CO2 — Where CO2 is the CO2 concentration in ppm, then the formula:
T(K)=293.73 + 0.8668*Log2(Z) + (log2(Z)/12.7857)^7
seems to match my recent MODTRAN results for values from zero to 71,680 ppm CO2 within 0.12 degrees K for 292.993 W/m2 Iout in tropical clear air.
The third term, LOG2(Z) divided by 12.7857 and then raised to the seventh power looks like it would only begin to have an effect greater than one degree K at CO2 concentrations above 7,212 ppm. That assumes that MODTRAN is correctly modeling the real world at those extra high levels of CO2. Also, I believe this data just shows the raw CO2 effect without any natural compensation or exacerbation.
BTW, Log2(Z)=Ln(Z)/Ln(2) [=0.69315]
It does appear that MODTRAN is now yielding slightly different results (about -0.2 W/m2) than when I first compiled the table in my earlier post.
The seventh power log term that shows up in my MODTRAN data analysis does not change my opinion that the logarithmic nature of the effect of carbon dioxide is one of the key reasons for doubting the claims that anthropogenic carbon dioxide is having a serious effect on our climate. That is because this effect only shows up at very high CO2 concentrations
The seventh power term seems to become significant around 18 times our current CO2 level. We would have to put about 72 times as much CO2 into the atmosphere as we have in the last century or so to get the CO2 concentration that high. I am not sure that we could do this even if we wanted to.
As CO2 is not, as some appear to have been conditioned to think, an actual source of heat, it seems only natural to assume that the range of any simple linear logarithmic effect approximation would be limited by a pinch-off effect. This is because the gradually expanding CO2 absorption band is progressively reducing the width of the earthshine transmission window and surface temperatures must increase to force the same amount of power through this narrowing constriction.
Also, there are also other trace isotopic varieties of CO2. The most common on Earth (about one percent of natural CO2) has two extra neutrons in one of its oxygen atoms. Each of these abnormal CO2 ‘isotopologues’ may have their own unique absorption spectra and I suspect these could become significant at 10 to 100 times our current CO2 concentration levels.
Also, once again, I do not know how accurately MODTRAN models the real world at these extra high CO2 concentrations. Perhaps someone with a better understanding of this whole problem could explain why the seventh power term appears to fit the data so well.