Guest post By Ben Herman and Roger A. Pielke Sr.
During the past several months there have been various, unpublished studies circulating around the blogosphere and elsewhere claiming that the “greenhouse effect” cannot warm the Earth’s atmosphere. We would like to briefly explain the arguments that have been put forth and why they are incorrect. Two of the primary arguments that have been used are
- By virtue of the second law of Thermodynamics, heat cannot be transferred from a colder to a warmer body, and
- Since solar energy is the basic source of all energy on Earth, if we do not change the amount of solar energy absorbed, we cannot change the effective radiating temperature of the Earth.
Both of the above statements are certainly true, but as we will show, the so-called “greenhouse theory” does not violate either of these two statements. (we use quotation marks around the words “greenhouse theory” to indicate that while this terminology has been generally adopted to explain the predicted warming with the addition of absorbing gases into the atmosphere, the actual process is quite a bit different from how a greenhouse heats).
With regards to the violation of the second law, what actually happens when absorbing gases are added to the atmosphere is that the cooling is slowed down. Equilibrium with the incoming absorbed sunlight is maintained by the emission of infrared radiation to space. When absorbing gases are added to the atmosphere, more of emitted radiation from the ground is absorbed by the atmosphere. This results in increased downward radiation toward the surface, so that the rate of escape of IR radiation to space is decreased, i.e., the rate of infrared cooling is decreased. This results in warming of the lower atmosphere and thus the second law is not violated. Thus, the warming is a result of decreased cooling rates.
Going to the second statement above, it is true that in equilibrium, if the amount of solar energy absorbed is not changed, then the amount of IR energy escaping out of the top of the atmosphere also cannot change. Therefore the effective radiating temperature of the atmosphere cannot change. But, the effective radiating temperature of the atmosphere is different from the vertical profile of temperature in the atmosphere. The effective radiating temperature is that T that will give the proper value of upward IR radiation at the top of the atmosphere such that it equals the solar radiation absorbed by the Earth-atmosphere system.
In other words, it is the temperature such that 4 pi x Sigma T4 equals pi Re2 Fso, where Re is the Earth’s radius, and Fso is the solar constant. Now, when we add more CO2, the absorption per unit distance increases, and this warms the atmosphere. But the increased absorption also means that less radiation from lower, warmer levels of the atmosphere can escape to space. Thus, more of the escaping IR radiation originates from higher, cooler levels of the atmosphere. Thus, the same effective radiating temperature can exist, but the atmospheric column has warmed.
These arguments, of course, do not take into account feedbacks which will kick in as soon as a warming (or cooling) begins.
The bottom line here is that when you add IR absorbing gases to the atmosphere, you slow down the loss of energy from the ground and the ground must warm up. The rest of the processes, including convection, conduction, feedbacks, etc. are too complicated to discuss here and are not completely understood anyway. But the radiational forcing due to the addition of greenhouse gases must result in a warming contribution to the atmosphere. By itself, this will not result in a change of the effective radiation temperature of the atmosphere, but it will result in changes in the vertical profile of temperature.
The so-called “greenhouse effect” is real. The question is how much will this effect be, and this is not a simple question. There are also questions being raised as to the very sign of some of the larger feedbacks to add to the confusion. Our purpose here was to merely point out that the addition of absorbing gases into the atmosphere must result in warming, contrary to some research currently circulating that says to the contrary.
For those that might still question this conclusion, consider taking away the atmosphere from the Earth, but change nothing else, i.e., keep the solar albedo the same (the lack of clouds would of course change this), and calculate the equilibrium temperature of the Earth’s surface. If you’ve done your arithmetic correctly, you should have come up with something like 255 K. But with the atmosphere, it is about 288 K, 33 degrees warmer. This is the greenhouse effect of the atmosphere.
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I just had to share this from another blog with you.
DirkH Says:
July 22, 2010 at 9:55 pm
“To see what will happen, here are some pictures of the snow catastrophy of 1978/79 in Northern Germany.
This is what awaits many people when the winters get harder.”
DirkH Says:
July 22, 2010 at 10:05 pm
“One more word: 12 people died in Western Germany. Intense rescue efforts by the army freed most of the people lost in villages from their peril.
In Eastern Germany, Communist at that time, the entire energy production shut down. Shortly before they had decided to use only home-grown brown coal power plants to become independent. The cold meant they were no more able to dig the humid brown coal so they had to shut off all power plants.
How many people died in Eastern Germany was never communicated. It must have been far more than the 12 in the west – it was a country with 14 Million inhabitants under a total blackout in winter!
So the technology of the West saved our asses. The run-down technology of the East failed spectacularly.
The West immediately offered help. The West asked the communists what they needed; rotary hammers they said, and within 3 hours some trucks with a few hundred rotary hammers were at the border so they could hammer some brown coal out of their pits to restart energy production.
Technology saves your ass. And only technology.”
http://pgosselin.wordpress.com/2010/07/22/noaa-models-predict-big-arctic-deep-freeze/
All climate forecasts need to take a lesson from economics. There is a Latin phrase which is used (not over used) in economics. That phrase is: Cēterīs paribus.
Unfortunately in climatology, as in economics, one cannot hold all other things equal (constant). This is where the “rub” is. The AGW concept may be right in theory, but it will never be useful in forecasting the earth’s climate because there are so many many other factors in play. I doubt that no one really knows what all those factors are; nevermind being able to model their effects and the interplay amongst all of those factors.
This is amongst my biggest complaints about the AGW concept (that controlling ONLY the relative amount of CO2 in the atmosphere will greatly impact Global Warming). What is also so remarkable about the AGW concept is that such an infintesimally small change in the relative amount of CO2 in the Earth’s atmosphere can have such an enormous impact on the Earth’s average temperature (assuming that anyone can accurately calculate what it is).
Stephen Wilde says:
July 23, 2010 at 9:22 am
Thanks Stephen; that’s it.
My great grandmother used a hot water bottle, now she would use instead a hot water bag. One more curious thing: She used, also, water bottles made of glass of different colors, which she put under the sun light to drink that for different ailments.
The surface warming part of the ‘greenhouse effect’ is just the downard IR radiation from the atmosphere to the surface. Most of this originates in first kilometer layer above the surface. However, there is no equilibrium. The temperature of this layer is mainly set by convection from the surface. The idea that CO2 can cause any kind of climate change is incorrect.
The surface heating is dynamic. The daily heat load hitting the surface can be up to 30 MJ/day – varying continuously during the day. At night the cooling is between about zero and 360 kJ per hour depending on humidity and cloud cover. Over the last 200 years the 100 ppm increase in CO2 has produced an increase in downard ‘clear sky’ LWIR flux of 1.7 W.m-2. That is 6 kJ/hour or 0.15 MJ perday. Add this to the rest of the surface surface flux and it is buried in the noise. The surface flux is also coupled into the surface and heats the ground down to about 1 meter.
IT IS IMPOSSIBLE FOR A 100 PPM INCREASE IN ATMOSPHERIC CO2 CONCENTRATION TO CAUSE ANY KIND OF CLIMATE CHANGE
There is no CO2 ‘signature’ in the meteorological surface air temperature (MSAT) record. This has been created from the ocean surface temperature changes along the path of the weather systems that show up in the MSAT. In the US it is just the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation. The hockey stick itself is not the major fraud. It is the use of the hockey stick to ‘calibrate’ the climate simulations that is the real fraud. The climate results are then used to perpetuate the rest of the ‘environmental disaster’ fraud. The increases in ocean surface temperatures from about 1960 onwards have been reprocessed into a ‘CO2 signature’ in the meteorlogical surface temperature record. The ocean surface temerpatures are now cooling so the fraud is finally being revealed. The oceans won’t ‘hide the decline’.
For more info go to Energy and Environment 21(4) 171-200 (2010) ‘A Null Hypotheisis for CO2’
http://multi-science.metapress.com/content/9p72043270187318/?p=186148f7bd6a4c1681163d19daa8aea0&pi=2
[Paywall, unfortunately – if WUWT sends me an e-mail address I can send a copy of the paper]
The altitude of a CO2 molecule makes a difference. The higher up it is, the larger percentage of re-radiated LW goes out into space due to the curvature of the Earth.
This shows what happens.
The fastest way to lose your soul: Change your creed to GWR religion.
Green house effect is not a source of energy; if it warms the surface, something else must cool; the cooling of the stratosphere can give an idea of how much the surface must warm, or how much heat is in the pipe (oceans)
With regards to the violation of the second law, what actually happens when absorbing gases are added to the atmosphere is that the cooling is slowed down. Equilibrium with the incoming absorbed sunlight is maintained by the emission of infrared radiation to space. When absorbing gases are added to the atmosphere, more of emitted radiation from the ground is absorbed by the atmosphere.
I have problems with this. You cannot absorbed more energy than is available to the receptive molecule. Perhaps Ben Herman and Roger A. Pielke Sr would like to quantify the amount of surface
emitted LWR that CO2 is receptive to that escapes directly into open space.
A greenhouse effect and a green house gas are different things. Greenhouse effect is caused by the fact that glass is semi-transparent to IR in both directions which causes IR to be trapped on the side away from the primary IR source. Thus the inside of a greenhouse (glass house) then becomes warmer.
A greenhouse gas which is often pumped into a greenhouse is CO2. This is done by commercial growers to increase plant growth (yields), not because it warms but because it feeds the plants by making the scarce CO2 more readily available for photosynthesis.
CO2 increases in temperature when exposed to sunlight. It does this by absorbing IR. This is neither due to a greenhouse effect nor is it a greenhouse gas when it is not in a greenhouse.
Can we drop the ‘greenhouse’ as either an adjective or adverb and find word(s) which correctly describe the phenomenon of its IR absorption properties and its effect on the atmosphere then planet in that order. The search for the correct descriptives may assist in critical thinking about the subject which is demonstrably sadly lacking in some quarters.
Monckton says:
“whether attempting to mitigate future “global warming” will make any real difference to the climate (it won’t: remember Canute), whether the cost of forestalling each degree of “global warming” will be disproportionate to the climatic benefit (it will), and whether focused adaptation to any change in the climate, where and if necessary, will be orders of magnitude cheaper than trying to prevent that change from occurring in the first place (yes).”
If some of the ice core data is correct, co2 and methane started increasing about 6 or 8 thousand years ago, about when men, due to a more beneficial climate, crawled out of their caves and began to farm and icrease their population. Can’t quote the study, but it was in “Scientific American” years ago when I still subscribed to that rag. The chart actually picked up the drop in c02 and methane that occured about the time of the two great plagues which substantially reduced populations around 450? and 1450? AD. Makes sense given what we do to warm ourselves (build fires), irrigate crops (rotting vegetation), raise livestock which defecate, as do we, etc. It would appear from that analysis that the only real reductions in these gasses which we could cause would require drastic depopulation of our planet. Of course I am doing what I hate here by implying cause and effect from a simple Algore type of chart.
As far as the cost of any potential change in our production of greenhouse gasses, I totally agree with your comments. Not going to the extreme of drastic population reduction, there will be little effect by other actions and significant socio-economic negative impacts as a result. We must, after all, continue to heat and eat. One can see it coming here with the various carbon tax schemes being planned by the US federal government which all will be detrimental to our economy and way of life while giving more control to the government. But that is the real goal in our particular situation.
Enneagram says:
July 23, 2010 at 9:27 am
There is no such a thing as the greenhouse effect, greenhouse gases are gases IN a greenhouse, where heated gases are trapped and relatively isolated not to lose its heat so rapidly. If greenhouse effect were to be true, as Svante Arrhenius figured it out: CO2 like the window panes in a greenhouse, but the trouble is that those panes would be only 3.8 panes out of 10000, there would be 9996.2 HOLES.
———————
This is, of course absolutely, correct if you are considering a planet with an atmosphere a single molecule thick. In an atmosphere two molecules thick, the number of holes would be 10000*0.9962^2 = 9924. Now consider how many holes there would be in an atmosphere only a million molecules thick (<<1mm). (10000*0.99962^1000000
PTCO.
It’s more than sad that people continue to fight against the basic physics. Physics that working engineers understand and use on a daily basis. The problem is this: The warmists have been very successful in lumping those of us who understand how GHGs work to warm the lower portion of the atmosphere, with those who deny this fundamental physics. They lump those who deny the science of GHGs with those who question the accuracy and completeness of our understanding of sensitivity.
GHGs will not cool the planet. There no science to suggest they will. C02 will warm the planet, up to limit. That limit has not been reached and the questions are:
1. how fast will we reach that limit
2. will it be damaging
3. Can and should we do anything about it.
Anthony,
you should read this article:
“[b] Falsi fication Of The Atmospheric CO2 Greenhouse E ffects Within The Frame Of Physics[/b]”
[b]Abstract[/b]:
The atmospheric greenhouse e ffect, an idea that many authors trace back to the
traditional works of Fourier (1824), Tyndall (1861), and Arrhenius (1896), and which
is still supported in global climatology, essentially describes a fictitious mechanism, in
which a planetary atmosphere acts as a heat pump driven by an environment that is
radiatively interacting with but radiatively equilibrated to the atmospheric system. Ac-
cording to the second law of thermodynamics such a planetary machine can never exist.
Nevertheless, in almost all texts of global climatology and in a widespread secondary
literature it is taken for granted that such mechanism is real and stands on a rm sci-
enti c foundation. In this paper the popular conjecture is analyzed and the underlying
physical principles are clarified. By showing that (a) there are no common physical laws
between the warming phenomenon in glass houses and the fictitious atmospheric green-
house eff ects, (b) there are no calculations to determine an average surface temperature
of a planet, (c) the frequently mentioned difference of 33 C is a meaningless number
calculated wrongly, (d) the formulas of cavity radiation are used inappropriately, (e) the
assumption of a radiative balance is unphysical, (f) thermal conductivity and friction
must not be set to zero, the atmospheric greenhouse conjecture is falsified.
Electronic version of an article published as International Journal of Modern Physics
B, Vol. 23, No. 3
http://arxiv.org/PS_cache/arxiv/pdf/0707/0707.1161v4.pdf
Good article. Second time I read it today. I’ve always accepted the greenhouse effect because it just seems intuitive. However I have recently been reading some of the work by some of those who are skeptical of the greenhouse effect theory and they make compelling arguments.
So let’s just assume the greenhouse effect is real and it is responsible for the planet being about 33 degrees K warmer than it would be without it. If water is responsible for 95% of the effect, does that suggest that all the remaining GHGs are responsible for only about 1.6 degrees K of the total effect? I suppose this is the central question. Just how much warming (or reduced cooling) is likely to result from a doubling of atmospheric CO2 concentration? As I understand it, a doubling would theoretically result in about 1.2 degrees K of apparent warming. Is this even significant?
An excellent article. It is not an easy thing to make the complicated understandable.
The absorption of radiant heat in the atmosphere was studied in detail long before climate scientists began getting involved. As an example, those who question Dr. Pielke’s explanation must explain why it is that blast furnace calculations work. These too account for the amount of heat absorbed by the atmosphere and the subsequent increase in temperature of the atmosphere.
The blast furnace calculations for radiant heat transfer are identical in form to those used to estimate the absorbance of radiant heat in climate research. Climate science is not the only area where these calculations are performed. In other areas, there is little disagreement with Hansen / Ramanathan.
My only issue is that in other areas, the impact of CO2 is asymptotic, parallel to the x axis to a line at about 500 bar.cm with nearly 0 increase after 100 bar.cm. (See “Heat Transfer Handbook, Bejan And Kraus, Pg 618). Using the methods taught me, I come up with a curve nearly identical to F=5.35ln[CO2], diverging at about 100 ppm CO2 and basically F=0 after 200 ppm CO2.
The graphic accompanying the article is not helpful to those of us who need education because it does not show the relevant mechanisms. Could someone please post a graphic that covers the molecular level, sort of a “Radiation’s Quest for Space” graphic that shows radiation leaving the cooling black asphalt and all the adventures it might have, especially encounters with CO2 molecules, as it heads for space?
There’s a basic physics’ problem. To state “The bottom line here is that when you add IR absorbing gases to the atmosphere, you slow down the loss of energy from the ground and the ground must warm up.” is only correct if the extra CO2/CH4 etc. does not trigger a reduction of water vapour concentration. The evidence here [ http://docs.google.com/leaf?id=0B74u5vgGLaWoNDFjODAwMWMtNmNmYS00NDhmLWI3NjItMTE0NGMwNWMxYjQ2&sort=name&layout=list&num=50 {sorry, needs Google Mail account to read}] indicates that over the past c. 60 years, as CO2 has increased, the water average vapour concentration in the atmosphere has decreased. So, whilst the land/water/lower atmosphere have warmed, there has been no apparent change of the integrated atmospheric IR absorption properties. If true, this indicates that the extra CO2 has not caused the warming so the latter may have been due to a natural process(es).
The above paper by ex-NASA scientist Miskolczi should be read in conjunction with his 2006 paper which suggests a thermodynamic equilibrium argument for this control mechanism. If true, it indicates a Gaia-type mechanism with an interaction between the IR adsorption column properties, the transport of latent heat upwards, liquid/solid water downwards.
So, no argument about higher temperatures, just be careful about the claim that this is firm evidence of global warming!
“”” Jeff says:
July 23, 2010 at 8:20 am
slowing down the cooling of an object cannot cause it temperature to rise … THAT would violate the 2nd law … “””
Jeff, if only you knew just how much, a statement such as you just made lowers YOUR credibility (as to knowledge of thermo-dynamics.)
Let us take as the (your) “object” a small spherical “Blackbody”; might as well make it the size of a tennis ball, say about 5 cm diameter. I choose a “blackbody”, simply because you did not exclude it from your “object” category; and other than that it is a simple thing to understand. In the end though, it matters not that I choose a blackbody. And since we are doing this; stick in the sand wise, I will also make the body to have infinite thermal conductivity; well very high anyway; and it is a thin shell like a ping pong ball so that it is of very low mass and heat capacity.
So we put our ball out in space in earth’s orbital position (from the sun) to soak up solar radiation at 1366 W/m^2 of intercept are exposed to the sun. All that incident energy gets absorbed; and since the ball is highly thermally conductive; it spreads uniformly throughout the ball, so the Temperature of the ball is the same all over the surface. BB radiation theory tells us that the ball will radiate uniformly (W/m^2) from all over the surface, as soon as its Temperature moves above zero Kelvins (absolute zero). With this loss of energy through radiation, the rate of increase of temperature with the incoming solar radiation, will slow down, since the energy arrives from the sun at a constant 1366 W/m^2, but leaves at a sigma.T^4 W/m^2 rate based on the Temperature. Since the total surface area of our uniform Temperature ball is four times the intercept area collecting solar energy, the uniform rate of energy loss from the ball, cannot exceed 1366/4 or 341.5 W/m^2 (Trenberth uses 342).
We know from our compendium of useless facts that must be remebered; that at 288 K; the mean earth Temperature; the rate of black body radiation is 390 W/m^2. So we are less than that. 0.875641 of that to be more specific; and we know from BB theory that that number varies as T^4.
So 4th root of 0.875641 is 0.967345, and we multiply that by the 288 Kelvins of earth Temperature and we get 278. 6 Kelvins, or about 5.45 deg C.
Well our authors above said 255 Kelvins; but they don’t have a black body; theirs has an albedo equal to Earth’s, and that is what lowers us to 255 K.
Ok so far so good. I deliberaterly chose a low thermal mass ping pong like ball so that it heats and cools very rapidly; if I make it thin enough it would change temperature in milliseconds or less, adjusting its Temperature so that incoming energy RATE always equals outgoing energy RATE (Watts).
Now you have declared that the cooling rate does not change the Temperature. Well specifically you said “”” slowing down the cooling of an object cannot cause it temperature to rise “””
So now I want to modify our ball to “slow down its cooling rate.” Well just to see if you are correct.
I’m not going to add an atmosphere to our ball; that just complicates things with hurricanes; and tornadoes and things.
So now I am going to fill our nearly massless ping pong ball with lead to increase its mass by a huge amount, and with a material that isn’t too great a thermal conductor either (for a metal).
Now a Maxwell’s Demon sitting on the surface of the sun looking at our new ball, is not going to “see” ANY difference in the appearance of the ball; but its gravimeter is going to detect that the gravitation pull of our modified ball on the sun has increased by a huge factor so it does know the ball is different; but not in external visual appearance.
Now the radiation impinging on our heavy ball is still totally absorbed; but now the ball is not infinitely thermally conductive, so the rate at which heat travels through the ball to the unradiated isde slows down as most of the heat has to propagate through the lead core, which isn’t such a great conductor.
Now notice that the thermal black body radiation being emitted from the surface of the ball, encounters NO impediment of any kind; it simply leaves as before, but the presence of the lead core slows down the rate that heat is moved from the sun side to the night side, which slows the rate at which the sun side can cool.
Since the night side can only radiate energy that comes to it from the sun side, by conduction through the ball, that heat can only flow, if there is a Temperature gradient through the ball to drive the heat. It is quite like Voltage across a Resistor driving a current through the resistor. No Voltage difference; no current flow.
So our ball can no longer be isothermal like it used to be. The sun side must get hotter since heat is arriving faster than it is being radiated (1366 W/m^2 in and 341.5 out) to that extra 1022.5 W/m^2 has to travel through the ball to get radiated from the rest of the surface.
The sun side Temperature increases above 278 K setting up a temperature gradient which starts to drive heat through the ball; but the night side must cool down since it waqs also radiating at 341.5 W/m^2; but we have slowed down the rate of supplu of that energy from the sun side, so the night side temeprature must fall, as well as the sun side heating up; and all this happened simply because we slowed down the rate of heat flow.
Eventually the situation will stabilize; with the sun side somewhat hotter than 278 K, and the night side somewhat cooler than 278 K and the Temperature difference is driving 1022.5 W/m^2 through the ball to other parts (on average).
Since the rate of loss of energy goes as T^4; so it is non-linear with temperature, the colder parts of the ball, are not doing their fair share of cooling, and the hotter parts are being overworked, and if we average the Temperature all over the ball surface that average will ALWAYS be hgher than the original case of an isothermal ball at 278 K all over.
Now I didn’t put any atmospheric impediment in the way of energy loss from the surface; I simply slowed down the rate at which that energy can be lossed; in this case by raising the thermal mass and hence thermal time constant of the ball.
We have such a ball in the solar system. The Planet Mercury keeps one face facing the sun almost all the time; and it isn’t highly thermally conductive, and has no impeding atmosphere and the sun side is much hotter than the night side.
You get into real trouble trying to apply Second Law concepts to Electromagnetic Radiation. EM radiation IS energy; but it is NOT HEAT; and the second law applies to HEAT transport; NOT energy transport.
A photon emitted from some interstellar molecule at a Temperature of say 3 Kelvins; the background Temperature, can easily impinge on the surface of the sun and be absorbed; or for that matter on the surface of some Neutron star at some totally enormous Temperature. Photons don’t know ANYTHING about Temperature; they can come from anywhere and go anywhere without impediment.
Well, hold on. A planet without an atmosphere would be at a certain surface temperature defined by surface albedo and stephan-botlzmann’s law. Would the surface temperature of that planet be the same with a massive atmosphere that was completely transparent to all radiation? No, because the atmosphere would still affect the temperature of the planet through conduction and convection, to the point thatthe same radiative balance would exist at the top of the atmosphere, the surface being at a higher temperature than without an atmosphere, due to the physics of the lapse rate.
Remember, this test assumes an atmosphere completely radiativeely transparent to all wavelengths, but allows for convection and conduction.
My point is, radiative processes are not the only ones governing the temperature of the plane. Conduction and, especially, convection and evaporation, are not understood, complex and ignored.
How much of the 33 k is due to clouds?
I’m not a fan of (too) simple models of the type presented here.
It is no easier for lay persons to understand this type of model than it is for them to understand ones that are considerably closer to the reality (Mother Gaia’s model).
The idea that somewhere in the earth’s atmosphere there is a layer that has some “effective Temeprature” and from that layer ALL of the radiation of the planet is emitted to space in some black body like radiation spectrum at that characteristic Temperature; is quite incorrect; and quite misleading to the lay reader.
YES the earth’s atmosphere at ALL levels is emitting a thermal radiation spectrum IN ALL DIRECTIONS; and some of that returns to earth which DELAYS its loss to space (but DOESN’T prevent it); and some of it is directly lost to space. Some of it also is RE-ABSORBED by other atmospheric layers (and their GHG molecules).
The earth’s surface itself (solid and liquid) is a majort source of thermal EM radiation with a spectrum that is characteristic of the surface temeprature (principally); and a good deal of that radiation goes right through the atmosphere unimpeded to be lost to space with a spectrum characteristic of the surface temeprature of that particular surface element.
As a result; the earth’s external emission spectrum is not a simple Black Body spectrum of an isothermal body at 288 K or any other single Temperature.
But other than that, I’m supportive of the authors. The Second Law of Thermodynamis is a dog that won’t hunt in this field; and the “Greenhouse” effect; as well understood in climate science as opposed to agriculture IS A VERY REAL EFFECT.
The important point is that although the greenhouse effect is real, and does raise earth’s temperature above some BB theoretical equilibrium Temperature; THAT IS NOT WHAT IS CONTROLLING THE EARTH’S TEMPERATURE RANGE !!!
HEY ! IT’S THE WATER !!! (ever heard of clouds ?)
PS I have also been working on the validity of the claim in many of the IPCC models that high AGW/high feedback has so far been partially masked by man-made cooling via aerosols decreasing cloud droplet size thereby increasing albedo. This greatly worries the modellers because of the uncertainties of cloud physics although the direct aerosol effect has been verified by Mt. Pinatubo.
The problem is the cloud theory [Twomey 1974] uses a very simplistic approximation to the physics. Whilst it does successfully predict increased albedo for thin clouds with smaller droplets [e.g. ship’s track clouds], it cannot apply to thick clouds. Also, if you think about it, once the light entering a cloud becomes fully diffuse, the maximum albedo is 0.5; 0.7 is common, I’ve seen 0.9 quoted, there’s an unpredicted angular dependence and no apparent difference of albedo between thick polluted and thick unpolluted clouds.
So, there’s probably another optical process giving enhanced back-scattering at the tops of clouds: I think I’ve worked out why but the maths is horrific. No man-made cooling from polluted clouds means either the assumptions about AGW in the models are wrong, they’ve been wrongly calibrated, or both. I prefer the combination.
Steven Mosher says:
July 23, 2010 at 10:50 am
(…)
GHGs will not cool the planet. There no science to suggest they will. C02 will warm the planet, up to limit. That limit has not been reached and the questions are:
1. how fast will we reach that limit
2. will it be damaging
3. Can and should we do anything about it.
———————Reply:
It gets far more complicated than that. First you must defend your term “damaging”. Many (like myself) see far more benefits to an increase in CO2 than the problems, hence one might argue that “damaging” is an unfortunate choice of words; perhaps switch #2 with the statement “What will be the impacts, if any”. Then it gets even worse (if that’s possible), since your #3 gets to the truly messy part of balancing interests regarding a subject for which there is precious little concensus.
What may be of great interest (and a source of substantial grant funding) to a scientist may be conveyed as horribly unsettling by someone ideologically driven for political purposes yet, if left alone, could be beneficial with an overall improvement in society as a whole. Everybody with an opinion needs to be asked simply: “What is your vested interest?”
“Patrik says:
July 23, 2010 at 11:06 am
How much of the 33 k is due to clouds?”
A good question but even more to the point how much of that 33K is due to liquid water oceans.
The air even in it’s entirety could well be a total irrelevance in comparison.
Dr David says:
July 23, 2010 at 8:29 am
How much of the 33 degrees is due to heat escaping from the Earth’s core and tidal forces?
It’s not necessary to calculate this as we are talking about climate variables and not energy constance.