Guest post by John Kehr from: The Inconvenient skeptic
There are many times when I am putting together articles that I need to compare the results of my research to the models of the theory of Anthropogenic Global Warming (AGW). In this manner I can contrast the results and predictions directly. This way I understand how the different views relate to each other.
Recently I was trying to find the total amount of energy (forcing) that the warmists claim CO2 is responsible for in the atmosphere. The reason I wanted this is because I have recently completed my full analysis of absorption and I wanted to compare my results to the warmist views. While this article is not about my results, it will focus on some interesting results that I found using their models. Because I was searching for the warmist views about energy I was using information from their sites (and citations of course). While that might seem strange, they generally have lots of good information there.
The starting point is the basic equation they use to determine the forcing caused by a change in CO2 concentration.
CO2 Forcing Equation
This equation provides the amount of energy in W/m2 that a difference in two CO2 concentrations should cause.
While looking for the total forcing of CO2 in the atmosphere, I found an interesting article on the Skeptical Science (SkS) site that had an answer to my question (citation). They state that the radiative flux caused by CO2 is 32 W/m2. I will use the information from that article several times. When I compare the energy calculated by the forcing equation using CO2 levels of 1 ppm and 390 ppm I get a result of 31.9 W/m2. So far things are looking consistent for the theory of AGW. Here is a chart of the forcing from 1 ppm to over 1000 ppm.
Proposed Model of CO2 Forcing
The next step is to determine how much warming this energy causes. For this I use the next important equation that the AGW model uses. That is the climate sensitivity.
Climate Sensitivity: Warming caused by Forcing
Again I found lots of discussion and references at the SkS website (Hansen et al. 2006) where they provide their views about climate sensitivity. This equation is straightforward and simple to decipher. They generally calculate it by looking at a period of time with a temperature change and then estimate the change in forcing. For example if increasing CO2 caused a forcing of 2 W/m2 and the observed temperature change was 5 °C, then the climate sensitivity would simply be 2.5 °C /(W/m2).
One thing to be aware of is that the sensitivity is usually not shown directly. Most warmist publications display the results in terms of temperature change that will happen as a result of forcing. For example the most commonly used quantity for climate sensitivity is 3.0 °C for a doubling of CO2. To determine the climate sensitivity they are using it is simply:
λ = (3°C / 3.7 W/m2 ) = 0.81 °C/(W/m2)
I am going to use the direct climate sensitivity instead of the temperature effect that a forcing will cause. This will make my numbers look a little different, but here is the conversion.
Proposed Range of Climate Sensitivity
When comparing climate sensitivity it is very important to know exactly which form is being used. I will be using the actual climate sensitivity instead of the CO2 doubling form. The best way to check is to look at the units being used.
The most common estimate is the 0.81 °C/(W/m2). That is what corresponds to the 3 °C temperature increase for a doubling of CO2. The full range is what I have shown in the table. Some estimates do go a little higher or lower, but the 0.43-1.13 °C/(W/m2) is the most widely accepted range.
SkS puts the climate sensitivity at the 0.81-0.92 °C/(W/m2). I am going to use the 0.81 °C/(W/m2) as the default value for the warmists as it is the most commonly used value.
So far all of this seems perfectly reasonable and hopefully acceptable. This is also where the wheels start to come off.
I decided to look at another method to determine the climate sensitivity. I am troubled by the method normally used because it is very hard to know the exact forcing and cause of the temperature change. So I decided to use what should be a less controversial method, but somehow I doubt it works out that way.
I decided to use the total Greenhouse Effect (as the ΔT) and then the energies involved. The total Greenhouse Effect is perhaps the least controversial aspect of the Global Warming debate. I will use the normally accepted value of the Greenhouse Effect as 30 °C.
Now by using the climate sensitivity value it is possible to compare what portions of the Greenhouse Effect (GHE) are caused by different components. Since the accepted forcing value for CO2 is accepted as 32 W/m2 it is now possible to determine the total impact that CO2 has on the total GHE.
ΔT = (0.81°C/(W/m2)) * 32 (W/m2) = 25.9 °C
While that might not immediately seem unreasonable. The entire stated effect of the GHE is 30 °C. So according to the accepted climate sensitivity and CO2 forcing equations, CO2 accounts for 86% of the total GHE.
So all other factors in the Earth’s climate account for 14% of the GHE and CO2 by itself accounts for the other 86%. This can also be compared to the number of CO2 doublings that take place from 1 ppm to 390 ppm. That is roughly 8.6 CO2 doublings (1,2,4,8,16,32,64,128,256,390 ppm). Using 8.6 doublings from 1 ppm gives 25.8 °C. So their model is coherent, but saying that CO2 causes 86% of the GHE is extremely incorrect.
This means that the methods being used for determining temperature change based on forcing and climate sensitivity are flawed. Any result that puts CO2 at 86% of the GHE is wrong. Earlier I showed that the forcing model and the accepted total forcing have a good match. That would indicate that the problem is with (at least partially) the estimated climate sensitivity.
So I worked backwards. Assuming that the total temperature change caused by the GHE is 30 °C and then the total energy inputs are the total forcing. The total GHE is not very controversial. Very few people will argue that the Earth is not warmer as a result of the atmosphere. Without the atmosphere the Earth would be around -15 °C and with the atmosphere it is currently about 15 °C. That 30 °C difference is caused by the insulative effect caused by the atmosphere.
That leaves forcing as the problem in determining the correct climate sensitivity. The same article that stated CO2 as 32 W/m2 also stated that water vapor causes a forcing of 75 W/m2. If I assume that water vapor and CO2 are the ONLY factors I get a total forcing of 107 W/m2. This would indicate:
λ(30%) = (30°C /107W/m2) = 0.28 °C/(W/m2)
Already using very poor assumptions the climate sensitivity is already much lower (by almost 3x) than the accepted value. This still puts CO2 at 30% of the total GHE, so even this estimate for climate sensitivity is still too high.
The normally discussed range of CO2 effect on the GHE is 9-26%. Assuming that the 32 W/m2 remains accurate for the forcing magnitude of CO2 results in climate sensitivities of:
λ (9%) = (30°C / 356 W/m2 ) = 0.08 °C / (W/m2 )
λ (26%) = (30°C / 123 W/m2 ) = 0.24 °C / (W/m2 )
At 9% of the GHE the climate sensitivity must be 10x lower than what is currently accepted. There is one more possible scenario that I want to cover.
If I look at the Radiation Budget (Kiehl, Trenberth 1997) I get a total forcing from the surface to the atmosphere of 452 W/m2. That would include the energy from evaporation, convection and radiative transfer and subtracting out the open window of 40 W/m2. If I use the 32 W/m2 for CO2 with that total energy then CO2 accounts for 7% of the total GHE. Then the climate sensitivity is:
λ (total energy) = (30°C / 452 W/m2 ) = 0.066 °C / (W/m2 )
That is what the real lower limit of the climate sensitivity is. The flaw in the estimates for climate sensitivity is the assumption that all temperature change is caused by the greenhouse gas forcing. If the climate was as sensitive as the much higher estimates currently in use are, the Earth would be a very unstable place as small changes in energy would cause large changes in temperature.
Using the total GHE determined climate sensitivities, here are the CO2 doubling effects on the climate.
GHE Determined Climate Sensitivities
What this shows is that trying to determine the climate sensitivity from a change in measured temperature and then assuming it was caused by a particular forcing is incompatible from the determination of climate sensitivity from the actual GHE. In choosing between methods it is the GHE that is a known quantity. Since the measurements have been done to determine the individual parts of the GHE, that seems to be a much more reliable method than “assuming” that a particular forcing caused a certain change in temperature.
The IPCC and the general AGW method of determining climate sensitivity is about an order of magnitude different than the method of using the total GHE and then calculating the components. This is a significant scientific disparity.
The difference the climate sensitivity makes to the temperature projections based on increasing CO2 concentrations are significant. Assuming the same CO2 forcing while using the different climate sensitivity values results in the following effects of CO2 on the global temperatures.
Red: The AGW accepted climate sensitivity of 0.81 (3C for doubling) Green: Climate sensitivity of 0.28 (1C for doubling) Blue: Climate sensitivity of 0.066 (0.24C for doubling)
The total GHE of 30 °C is incompatible with the currently accepted IPCC values of climate sensitivity and CO2 forcing. In order for the GHE to be compatible, the total effect of the greenhouse would have to be closer to 100 °C which would result in a global temperature of ~85 °C. This strong overstatement of the climate sensitivity substantially weakens the idea that CO2 could cause measurable change in the Earth’s climate, much less the type of danger that is often being stated.
This does not mean that CO2 is not a significant portion of the Earth’s greenhouse, but it does limit the role that it plays in the total GHE. The climate sensitivity is what prevents the sum of the parts from being greater than the whole and the sum of the parts cannot be greater than the total observed GHE. If the current estimates of CO2 forcing and climate sensitivity do not fit within the parameters of the total GHE effect, those estimates must be incorrect.
JDN says:
October 25, 2010 at 1:00 pm
DesertYote says:
October 25, 2010 at 12:01 pm
richard telford says:
October 25, 2010 at 7:51 am
There was a similar post to this on WUWT a month or two back. Not surprisingly they share the same flaw.
The greenhouse effect of 30C is for a planet with an albedo of 0.3. The earth would not be cooler by more than 30C if the atmosphere was not radiatively active because the albedo would increase because of increased snow and ice cover.
#
What does a state change discontinuity at boundary have to do with the anything?
————————
@DesertYote: It’s the difference between walking on water and walking in water.
@Telford: I assume that he meant “all things being equal”, as in equal albedo, the earth would be 30C colder. Since it’s an analysis of formulas, that seems reasonable. Is this going to be a problem for you?
###
I said discontinuous state change at a boundary, as in domain boundary. Your analogy is for a discontinuity within the problem domain. Try again.
MarkR says October 26, 2010 at 6:27 am
You must live in a different world than I do … in my world, when you heat water up with sunlight some of it evaporates …
Dave, I don’t think we are disagreeing. I was trying the make the point that — if you want to know about the IR coming and going from the surface at any given time, the temp at the surface is all you need to know.
Certain
>> “The surface itself would still be around 15 C.”
> That depends on a whole bunch of factors. It’s 15C on average 15 thousand years into an interglacial period. During the peak of the glaciation cycle the surface is going to be largely ice with an average temperature well below freezing.
AGREED 🙂 And if a square meter of the ocean surface is 15 C at a specific time (or 13 C or 18 C) then that square meter will radiate IR like water at 15 C (or 13 C or 18 C). And then you could average the temperatures and get some sort of global average. I have no special expertise in that area, so I was just using 15 C that had been presented as a reasonable number for the sake of discussion.
>>“And that 15 C surface temperature is all that matters for IR radiation to
>> the atmosphere. (Kinda like rocks deeper down are much hotter, but that
>>doesn’t affect the IR radiation either.)”
> … There is no comparison in this regard between the earth’s crust
> and the global ocean.
The one comparison — the one I apparently did not make clearly — is that we don’t need to know ANYTHING about the deeper layers to know about the surface IR. As you said (and I said in a later post) the internal details are vastly different. But if the temperature and the material of a surface are known, IR characteristics are determined. No IR comes from 1000 ft down, so whether it is hotter at that depth (like the land) or colder (like the ocean) is immaterial to the surface IR.
Hopefully I made my point more clearly now. 🙂
George E. Smith says:
Well how about a little consistency. either the global mean surface Temperature is a linear function of the log of the CO2 abundance, or it isn’t. Climatism 101 says it is; and if we accept that, then John’s numbers are correct.
That’s exactly the problem. It isn’t. There are many factors that contribute to rising mean global surface temperature besides CO2. Among the most important just off the top of my head:
1. Rising temps caused by CO2 allow the atmosphere to hold more water vapour. This is a greenhouse gas with more than double the effect of CO2. It is a feedback rather than a forcing, but it still results in rising temps beyond what CO2 alone is responsible for.
2. Rising temps cause glaciers, snow, and arctic ice to melt, thus reducing the Earth’s albedo. Less reflected sunlight means more absorbed sunlight/IR. Temps go up.
The GCMs take much more than CO2 into account. Trying to set up CO2 as the sole contributor to warming is setting up a straw man.
Your post is the very first time I have ever seen anybody refer to Climate Sensitivity as the rise in mean global surface temperature for an increase in CO2 from 280 ppm to 560 ppm. It is almost universal to refer to the Temperature rise per doubling; and that specifies a log function; which isn’t some arbitrary non linearity.
You misunderstood my post. I was correcting John Kehr’s egregious error in his understanding of what doubling meant. It refers to the doubling from *pre-industrial* CO2 levels. Thus the first doubling will occur sometime in the future. There are a lot of people, John Kehr included, who seemingly think that doubling has already occurred.
How many times do the same facts need to be repeated to you people? Oh, I know, an *infinite* number of times. Because it is your ideology that will not let you accept any science that would cause you to change your lifestyle. This is no different to creationists who refuse to accept evolution because it conflicts with their religion.
George E. Smith says:October 25, 2010 at 2:46 pm
Earth to Tim ! This planet has almost no other external energy input besides solar spectrum electromagnetic radiation from the sun; sunlight. Any reduction in sunlight for time scales of climate significance must result in a cooler earth.
I agree completely with your last sentence. But I don’t think that by itself negates what I was saying.
More specifically — Any reduction in sunlight for time scales of climate significance must result in a cooler earth as a whole (including the surface, the oceans and the atmosphere). So if the sun dimmed for some reason, then the earth as a whole would cool until it was emitting the same IR back to space as total solar radiation it receives. If liquid water (in the form of clouds) reflects some of that light away, then the earth as a whole would have to cool. By water vapor absorbing solar energy is still “part of the earth”.
“Ultimately, it is the total solar energy that EARTH ABSORBS that determnines its Temperature over climate times scales.=; and H2O ALWAYS reduces that.
Specifically, H2O vapor reduces the solar energy the SURFACE of the earth absorbs. “The earth” as a whole is still absorbing that energy. The “optical surface for IR” (somewhere up in the atmosphere) must be at an appropriate temperature (around 280 K give or take a bit) to radiate back to space the energy absorbed from the sun (whether absorbed by water in the atmosphere or by the surface itself). The physical surface does not need to be this temperature (and indeed is measured to be much higher than the blackbody temperature due to inputs from a slightly cooler atmosphere and a much hotter sun).
I think there are way to many issues involved to figure this out in a discussion of a blog about climate sensitivity. Perhaps some smaller group should chat off-line to come up with something we can agree on and make it a new blog here.
“”””” Tim Folkerts says:
October 26, 2010 at 12:55 pm
George E. Smith says:October 25, 2010 at 2:46 pm
Earth to Tim ! This planet has almost no other external energy input besides solar spectrum electromagnetic radiation from the sun; sunlight. Any reduction in sunlight for time scales of climate significance must result in a cooler earth.
I agree completely with your last sentence. But I don’t think that by itself negates what I was saying. “””””
Tim, Chasmod, is always chiding me for writing too fast; and he means too long. But it seems no matter how long I make a post; I still fail to communicate.
Yes it is true that earth’s Temperature depends on how much energy the EARTH absorbs; it also depends on how much solar energy REACHES THE PLANETARY SURFACE; meaning where the atmosphere terminates.
And as you point out solar energy that is intercepted in the atmosphere (mainly by H2O) isstill absorbed in what is a part of the earth.
I thought I explained quite clearly that energy from whatever source that is deposited in the atmosphere (and likely raises itsa Temperature, subsequently results in ISOTROPIC LWIR thermal emission; and ONLY HALF of that reaches the surface to get absorbed by something else(mostly the ocean surface).
The other half of that atmospheric radiation takes off for outer space; to get lost. Yes it is likely to be reabsorbed in the atmosphere (partly) and that will result in a further isotropic emission, only half of which will proceed downwards. The end result, is that energy; for example incoming solar energy that gets captured by the atmosphere and therefore does not reach the surface (as solar energy); ends up getting split about 50:50 and only half of it ends up at the surface where it becomes a part of the long term energy sink.; it is not stored for long periods in the atmosphere; so it is a total energy losing mechanism. Without the atmosphere it would all reach the surface and mostly get stored less a small surface albedo reflection loss.
Anything in the atmosphere which is capable by any mechanism of absorbing some part of the incoming solar spectrum energy from the sun; must necessarily reduce the total amount of solar energy the earth captures over time; and that must result in a lower mean global Temperature.
Now I’m not saying that the Temperature will decline linearly with the reduction in insolation. Corrective mechanisms like changes in cloud cover will likely alter the result; just as those same measures would adapt to a real change in the extra-terrestrial TSI.
People can nit pick all they want about what else might go on; but none of that changes the bottom line that the earth must cool if the total energy captured from the sun goes down; which it will, with more H2O in the atmosphere in any and all phases.
Well I just might make an exception for noctilucent clouds; maybe it is possible that they send solar spectrum energy earthwards, that wouldn’t happen without them. But then I don’t know that Noctilucent clouds actually glow as a result of being illuminated by the sun; rather than charged particle interactions for example. But I’ll just leave it as the exception that proves the rule. Good luck on explaining any global warming with noctilucent clouds.
This all reminds me of some horrible experiment trying to determine the relationship between the number of pins in a cat and the volume of its screech.
How many pins will it take to get a 92db screech on a standard cat etc. etc.
Have you ever tried to hold down a cat and stick in a pin? Ask any vet with scars down their face how they got them! Likewise, the atmosphere is not some passive entity that just sits there and gets warm according to some theoretical “cat-screech” equation. Like the cat it will be running round the walls doing everything you can conceive, puffing up in clouds, pouring IR into the vast emptiness of space … all helped along by IR cooling gas!
Yes somehow sensible people still seem to be able to sit and talk about the theoretical number of pins you can stick in a cat and the “cat-screech” sensitivity!
“”” Steve Metzler says:
October 26, 2010 at 12:41 pm
George E. Smith says:
Well how about a little consistency. either the global mean surface Temperature is a linear function of the log of the CO2 abundance, or it isn’t. Climatism 101 says it is; and if we accept that, then John’s numbers are correct.
That’s exactly the problem. It isn’t. There are many factors that contribute to rising mean global surface temperature besides CO2. Among the most important just off the top of my head:
1. Rising temps caused by CO2 allow the atmosphere to hold more water vapour. This is a greenhouse gas with more than double the effect of CO2. It is a feedback rather than a forcing, but it still results in rising temps beyond what CO2 alone is responsible for. “”””
Steve; you say:- “” 1. Rising temps caused by CO2 allow the atmosphere to hold more water vapour. “””
Let’s add:- “” 2. Rising temps caused by H2O allow the atmosphere to hold more water vapour. “””
and :- “” 3. Rising temps caused by CO2 allow the ocean to outgas more CO2. “””
and :- “” 4. Rising temps caused by H2O allow the ocean to outgas more CO2. “””
and:- “” 5. Rising temps caused by CO2 allow the ocean to “outgas” more water vapour. “””
and:- “” 6. Rising temps caused by H2O allow the ocean to “outgas” more water vapour. “””
and:- “” 7. Rising temps caused by sunlight allow the atmosphere to hold more water vapor “”””
and:- “” 8. Rising temps caused by sunlight allow the ocean to outgas more CO2 . “””
and:- “” 9. Rising temps caused by sunlight allow the ocean to “outgas” more water vapour. “””
Now there is a portrait of absolute symmetry.
Rising Temperatures; whether caused by sunlight, CO2 or H2O, allow the atmopshere to hold more water vapor; allow the ocean to outgas more CO2 (or take up less), and allow the ocean to outgas (evaporate) more water vapor.
So now where is the hidden label that says CO2 is a GHG but H2O isn’t. why isn’t the sun a GHG sicne it warms the atmosphere and th4e ocean just like other GHGs do.
And H2O of course is a feedback since it more CO2 causes more H2O; but more H2O also causes more CO2 so therefore CO2 is also a feedback; and more CO2 or more H2O causes more atmospheric and surface warming by sunlight so therefore sunlight too must be a feedback and not a GHG.
I suggest Steve, that the Emperor has no clothes; and there simply is no basis for quite arbitrarily labelling CO2 as a GHG and NOT a feedback; whereas H2O is a feedback and NOT a GHG and sunlight is neither a GHG nor a feedback. when ALL of them are warming various things.
And I am quite tired of that lame excuse that CO2 resides in the atmosphere for hundreds or thousands of years but H2O does not.
WHEN, was the last time that earth’s atmosphere was observed to be devoid of H2O; that sometime temporary visitor to our atmosphere ??
George E. Smith,
You can’t find any legitimate problems with the science, so instead you play with words. Have at it.
Sorry, I didn’t have time to read the article in enough detail. Silly question, but what do we mean by greenhouse effect? I’m assuming it’s the radiative effect, is that really contributing about 30degreesC? The reason I ask is because what about the fact that the oceans and atmosphere (and rotation of the planet so it is not always heating the same hemisphere) are transferring heat around the planet by conduction and convection. Doesn’t that ‘warm’ the planet, i.e. increase the average temperature because it reduces radiation loss from the surface because radiation is T to power 4, so the smaller the temperature range of the planet the less the total radiation loss for the same average temperature, or have I got my logic wrong?
This is my reasoning – I’ve probably got this all wrong, but I’m imagining 2 bodies in space heated by radiation from a star. One body has poor conduction of heat from the hot sunny side to the cold dark side, for simplicity I’ll assume the hot side is all one temperature, let’s say 4 units (where 0 units = absolute zero) so the heat lost from that side is proportional to temperature to power 4 or 4x4x4x4 = 256. The cold side has a temperature of 2 units, so is losing 2x2x2x2 = 16. Add the two sides together gives a grand total of 272 radiation loss and the average temperature is (4+2)/2 = 3. The other object has perfect heat transfer (or is spinning so fast) so both sides are the same temperature, if this temperature is 3.415 then each side is radiating 3.415 to power 4 = 136, so the total for both sides is 272 with an average temperature of 3.145, in other words, quite a lot warmer on average than the object with poor heat transfer.
So if I use the same simple logic to compare Earth and Moon, taking into account the differing albedos I come up with this (non radiative) heat transfer effect accounting for a large proportion (or may be almost all) of the difference in temperature of Earth and Moon. Mine was only an extremely simple calculation with finger in the air temperatures, really I guess it needs more accurate temperatures and to be integrated over a realistic set of temperatures over the entire surface at a typical point in time.
Am I missing something, doing it wrong or were my finger in the air temperatures too way off the mark?
[SNIP – violation of site policy – wtf@fu.com is not a valid email address. the fu.com domain is in Arlington, VA and your comment originates at The University of Reading, UK., until you use a valid email address, all of your comments will be discarded – Anthony]
“”””” MarkR says:
October 26, 2010 at 4:05 pm “””
Well Lacis et al have a problem if what they say will happen is true.
With little or no water in the atmosphere; there won’t be much in the way of clouds; and the earth albedo will be very much lower; and you will have the mother of all warming forcings from a near TSI level of 1366 W/m^2, instead of about 1000.
If you figure out the BB equilibrium Temperature it is no longer 255 K byt more like 276 K which is above zero.
So their model simply doesn’t work; and you don’t need any taxpayer financed supercomputers to figure that out’ a stick on a sandy beach will do.
Who’s playing with words ? I simply pointed out that the SCIENCE says that each of those things produces the same SCIENTIFIC results; so there isn’t any SCIENTIFIC basis for characterizing CO2 and H2O as different in their effects.
Both exhibit the characteristics of GHG forcings which is pure SCIENCE; and both cause “regenerative” sort of effects; which the climatists call FEEDBACK which is SCIENCE; so in no qualitative way are they different to where one can be called a GHG forcing, and the other a non-GHG feedback. It’s a quite arbitrary and UNSCIENTIFIC dsitinction.
But the climatists cchoose the most perjorative interpretation to make their unfounded case that H2O is not the most important GHG; which it clearly is.
Over the last 600 million years; CO2 has been all over the map; yet for hundreds of millions of years, that had absolutely no recorded influence on the Temperature which simply refused to budge. And that is from the peer reviewed Science; not any wordmanship from me.
Regarding : Tim Folkerts says:
October 26, 2010 at 11:46 am
“Dave, I don’t think we are disagreeing. I was trying the make the point that — if you want to know about the IR coming and going from the surface at any given time, the temp at the surface is all you need to know.”
Thanks Tim, a couple of thoughts: I was responding to this, ““I can’t see any way to escape the logic that more water vapor (and more GHG’s in general) should and do have a net affect of warming the planet.” My response was that the atmosphere could well be heating up, but the oceans could well be cooling during this same period, and increased atmosphere heating, leading to increased water vapor and clouds, could reduce the flow of energy into the oceans where the residence time of energy in the planetary budget is far longer then in the atmosphere. The net affect of water vapor could well be cooling or even Newtonia, “for every action there is an equall and opposite reaction” (-; just on different time scales.
As for this : “if you want to know about the IR coming and going from the surface at any given time, the temp at the surface is all you need to know.” I have several concerns. First it is not easy to KNOW the temperature at the surface and with out knowing the relative average humidity, even if the temperature was known within say .10 F, then one really knows little. Secondly of course one must know how much of the IR surface temperature is coming from above, it spectral band in detail, and how much is coming from below, the land and oceans, as both create the IR surface temperature. I do not see how just knowing it (a certain amount of IR radiation) is there, tells us it flow direction and residence time in the atmosphere or near and below the surface on 70% of the planet. My point is if the atmosphere heats up (due to increased water vapor) at the cost of reduced energy flow into the oceans where the residence time is far longer, the net long term result may be cooling, not warming. I hope I have expressed my self well.
George E. Smith says:
But the climatists cchoose the most perjorative interpretation to make their unfounded case that H2O is not the most important GHG; which it clearly is.
Please learn to read for comprehension. I’ve said up-thread several times that water vapour has more than twice the greenhouse effect of CO2. It’s hard to be logically consistent when you’re lying to yourself all the time, isn’t it?
Here is a different way to estimate atmospheric sensitivity based on Miskolczi’s 2007 paper.
http://met.hu/doc/idojaras/vol111001_01.pdf
Miskolczi gives the ratio of St (flux transmitted through the atmosphere, directly to space) to Su (upward flux emitted at the surface) as 1/6, which is adopted in the following.
The problem is to calculate the surface temperature of the earth including greenhouse effect but excluding all other effects such as evapotranspiration, convection, meridional atmospheric circulation, solar variation, etc. Based on Miskolczi’s St/Su ratio of 1/6, we take the no-atmosphere surface temperature of -18 degrees C and adjust it for the change of St/Su from 1 (no atmosphere) to 1/6 (greenhouse atmosphere). The calculation in Excelese is:
T = (0.7 * 1365/(1/6 * 4 * 5.67E-8))^0.25 = 399 ºK = 126 ºC
Where:
0.7 = 1 – surface albedo of 0.3
1/6 = St/Su ratio (Miskolczi 2007)
St = upward radiation power transmitted directly to space (“window radiation”) W/m^2
Su = upward radiation power at the surface W/m^2
1365 = incoming SW radiation power W/m^2
4 = ratio sphere surface to disk surface
5.67E-8 Stephan-Boltzmann constant, J/(sec*m^2*K^4) or W/(m^2*K^4)
0.25 = Stephan-Boltzmann exponent ^ -1
For the no-atmosphere case (substitute 1 for 6), T = -18 deg C which is the commonly accepted value.
The sensitivity based on this is
labmda = (126-(-18)) / (0.7 * 1365 * 5 / 4)) = 0.121 ºC/(W/m^2)
Where:
5 = reflects the excess of window flux, greenhouse atmosphere over window flux, no-atmosphere (= 6 – 1).
Sherwood Idso made several estimates of sensitivity
http://www.warwickhughes.com/papers/idso98.htm#e4
His best estimate based on the 8 cases he looked at is 0.100 ºC/(W/m^2)
This exercise tends to confirm the thesis of this posting and Idso’s work, which together with this calculation gives a value of about 0.100 ºC/(W/m^2).
George E. Smith says: October 26, 2010 at 2:07 pm
Anything in the atmosphere which is capable by any mechanism of absorbing some part of the incoming solar spectrum energy from the sun; must necessarily reduce the total amount of solar energy the earth captures over time; and that must result in a lower mean global Temperature.
OK — I will agree with that, but that is only half the equation. Since I agreed with you, I think you will have to agree with this:
“Anything in the atmosphere which is capable by any mechanism of absorbing some part of the OUTGOING RADIANT ENERGY from the EARTH; must necessarily reduce the total amount of OUTGOING RADIANT ENERGY the earth LOSES over time; and that must result in a HIGHER mean global Temperature.
If blocking incoming energy cools the earth, then blocking outgoing energy must warm the earth.
So then the question becomes “is water vapor better at blocking incoming solar radiation, or is it better at blocking outgoing terrestrial radiation?” Does this result in a net warming or a net cooling effect?
P.S. I’m not sure that “blocking energy” is really the best frame for discussing the issue, but even using this approach, the greenhouse effect shows up clearly.
Tim Folkerts;
So then the question becomes “is water vapor better at blocking incoming solar radiation, or is it better at blocking outgoing terrestrial radiation?”>>
Neither the water molecules nor the photons care much about direction, so it isn’t better or worse at one than the other. HOWEVER, the path of a given photon may take it past more water molecules and hence have a higher percent chance of absorption and re-emission. This is where the concept of averages falls apart. You can’t assign 364 w/m2 to the whole planet and call it a wash. A photon emitted at the equator is going to plonck straight into a band of water vapour measured in tens of thousands of ppm. Emitted at the south pole at -90 degrees, there’s not too much water vapour in the air so the percent chance of being intercepted is lower. BUT, there’s way more photons emitted at surface at the equator than there are at the south pole. It isn’t a straight forward better or worse.
“So then the question becomes “is water vapor better at blocking incoming solar radiation, or is it better at blocking outgoing terrestrial radiation?” Does this result in a net warming or a net cooling effect?”
That is only part of the question. The “blocked” incoming solar radiation also increases the energy in the atmosphere. The question perhaps better asked is ” How is the residence time of all incoming TSI affected by changes in various GHGs?
To Steve Meltzer and Tom Folkerts. Please take some time to read http://www.kidswincom.net/CO2OLR.pdf. You might learn something about relative sensitivies of OLR to water (all phases) and CO2. I’ll gladly answer any questions you may have about the analysis.
For those interested in meteorological data during a total eclipse of the Sun, for the eclipse of February 26 ‘98 in Venezuela, I offer the pages:
http://www.oarval.org/MeteorologiaALen.htm (Meteorology by Angel Laya)
http://www.oarval.org/seclps98en.htm (Images & Data)
http://www.oarval.org/SEclpsTechen.htm (Tech Data)
http://www.oarval.org/SEclpsen.htm (Observatorio ARVAL: Paraguaná Total Eclipse of the Sun – February 26 ’98)
Well one of our climate scientists Bill Kinimonth has been saying for some time now that doubling CO2 will cause about 0.3 degree centigrade change (not 3 degrees cent.). See:
So you have someone else with qualifications in agreement with your conclusions!.
davidmhoffer says: October 26, 2010 at 7:10 pm
>Tim Folkerts;
>So then the question becomes “is water vapor better at blocking incoming solar
> radiation, or is it better at blocking outgoing terrestrial radiation?”>>
Neither the water molecules nor the photons care much about direction, so it isn’t better or worse at one than the other.
Ah! But the light itself is different. The incoming light from the sun has much of its energy in the form of visible light, which passes quite easily thru the vapor and down to the earth – maybe 20% of the energy is blocked. But the outgoing radiation is almost entirely IR. I don’t have the specific numbers handy, but water vapor certainly blocks over half of the outgoing radiation.
So, in fact, water DOES block the energy differently in different directions.
I DO agree that different amounts of water vapor in different areas, along with different amounts of incoming solar radiation, means that simple averages are not sufficient to quantitatively determine the actual balance. For that we would really have to look sq km by sq km and add up all the results.
But then we would need a computer model! 😉
Steve Metzler says:
October 26, 2010 at 12:41 pm
“1. Rising temps caused by CO2 allow the atmosphere to hold more water vapour. This is a greenhouse gas with more than double the effect of CO2. It is a feedback rather than a forcing, but it still results in rising temps beyond what CO2 alone is responsible for.”
That’s utter nonsense and we wouldn’t be alive to talk about it if were true. Water doesn’t care what makes it warmer so more water vapor would spawn more water vapor in your thesis and we’d have a runaway greenhouse. Since the earth has never experienced a runaway greenhouse the positive feedback you describe simply and demonstrably does not exist.
The flaw in your thinking is that water vapor is lighter than air. Warmer surface temperature certainly does cause more evaporation but that water vapor quickly rises by convection and as it rises the pressure drops and as the pressure drops it cools. When it cools enough it reaches the dewpoint and condenses into a cloud. This is junior high school physical science called the water cycle.
The cloud of course with a top measured in kilometers above sea level then reflects about 85% of the sunlight hitting directly back out into space. Adding to this effect is that most of the remaining 15% that gets absorbed by the cloud is transformed from visible to infrared light still kilometers above ground level. The water vapor and other greenhouse gases between the cloud and the ground now serve to insulate the surface against the cloud adding to the cloud’s awesome power to cool the surface beneath it.
Further, there’s a thing called latent heat of vaporization that is a powerful force in removing heat from the surface. It takes one BTU to heat one pound of water by one degree. It takes over 1000 BTUs to change one pound of water into one pound of water vapor at the same temperature. So all that latent heat of vaporization is carried up from the surface by convection and released kilometers from the surface when water vapor condenses to form a cloud.
The bottom line is that any surface warming caused by CO2 does not cause even more warming through increased water vapor because the water cycle simply doesn’t work that way. The water cycle has a built-in inescapable negative feedback with regard to increased surface temperature. Write that down.
@Steve Metzler
October 26, 2010 at 12:41 pm
While we’re on the subject of CO2 here’s some more inconvenient facts from physics.
The surface warming effect of CO2 comes by way of it absorbing upwelling infrared radiation and re-emitting it in all directions with approximately half going back towards the surface. That surface is in fact over 70% the surface of a body of water. You can’t heat water with infrared radiation. Infrared radiation is completely absorbed by the first layer of water molecules at the surface. You can increase the evaporation rate of water with infrared light but you can’t heat it. So for most of the earth’s surface downwelling infrared radiation doesn’t do jack diddly squat to heat the surface – all it does is increases the evaporation rate. It simply speeds up the water cycle and since the water cycle is a self-limiting process with negative feedback there’s no surface warming. Any insulation effect of CO2 over water is defeated by an increase in heat transport (evaporation, convective rise, condensation) from the surface to kilometers above the surface where it can more easily escape to the cold void of space.
CO2 over land is a different story as land surfaces readily absorb infrared radiation. There you have a real honest-to-God surface warming effect because of it. But since land surfaces are less than third of the entire surface there’s only a third of the warming from CO2 that might otherwise be expected. This handily explains why the IPCC’s dire warnings about global warming fell so far short of observed warming and why the warming that is observed is primarily in the northern hemisphere because the NH has more land surface than the southern hemisphere.
I never expect anyone who drank the CAGW kool-aid to someone who lets facts get in the way of their beliefs but these sir are the facts and they are indisputable.