This simple visual analogy that Ron House has designed can help readers not familiar with a contentious atmospheric modeling issue get a primer on the it. While not a perfect analogy (and by definition analogies often aren’t) it does help convey an important point: the predicted red spot has not appeared. For the more technically inclined, or for those wanting more, Steve McIntyre posted an interesting discussion at Climate Audit. – Anthony
Guest Post by Ron House July 29, 2009
Let’s say it’s a cold night and Fred climbs into bed:
(A) Fred in bed.
Will Fred use a blanket to keep warm? If so, the air will heat up close to Fred because his body warms the air and the blanket prevents it from moving away. On the other hand, as the night progresses, the air beyond the blanket will cool:
(B) With a blanket, the warm air collecting around Fred warms him up.
In the picture, the “+” signs show air that becomes warmer, and the “-” signs air that becomes cooler.
Now what if Fred (forgetful Fred) didn’t use a blanket? The warm air escapes and tends to rise (warm air being less dense than cold air):
(C) With no blanket, warm air escapes and Fred shivers.
Poor Fred gets colder as the night wears on. But now we come to the point of the exercise: How do we know whether Fred used, or did not use, a blanket?
“Easy,” you say: “Take a look!” But let’s suppose that Fred is a very light sleeper, we dare not put on the light, so there’s no way we can see if there’s a blanket. But—surprise!—we just happen to have an infra-red scanner that can tell us the temperature of the air at various spots throughout the room. Depending on whether Fred uses a blanket, the temperature change in the room follows one of the two characteristic patterns we saw above; so if we check where the air gets colder and where it gets warmer as the night wears on, we know, for a fact, whether or not Fred used a blanket, even without being able to see it. If Fred did use a blanket, our scanner should show results like this (note how we can’t see the blanket, but we can be sure that it is there):
(D) Warm air collects in a contained region, so there must be a blanket.
On the other hand, if he does not use a blanket, we will see the temperature change in a pattern something like this:
(E) Warm air escapes upwards, so we are sure there is no blanket.
Once again, there is no doubt at all what is going on. In science, nothing is absolutely certain, but depending on which temperature pattern develops, we can be very, very sure indeed of the answer to the question: Did Fred use a blanket?
Now we can turn to the global warming question, whether the Earth is surrounded by a ‘blanket’ of anthropogenic (human-generated) greenhouse gas stoking up the temperature of the planet. The physics of a real blanket (as with Fred in the fable above) and a gaseous ‘blanket’ around the Earth differ, but just the same, different heat dissipation (or retention) processes will result in different characteristic patterns of temperature change. Just as Fred will be surrounded by something roughly resembling one of two quite different patterns of air temperatures, so likewise will temperature changes around the Earth have a quite definite pattern, depending on which climate theory is right. Scientists whose paycheck does not depend on agreeing with global warming alarmism will all agree with this simple statement. It’s part of the basic skill of having a ‘nose’ for physics.
What, then, are our main competing climate theories? The IPCC’s reports are based on results from a collection of climate computer models; they have nothing else. These are simply computer programs that, in essence, contain a computerised version of the assumptions and beliefs of the climate modeller as to how the climate of the planet works. Whether these assumptions are well-founded is another question, but the key point is that whatever these assumptions may be, when the climate model is run, it generates its ‘predictions’ by calculation of hypothetical futures for the behaviour of the atmosphere. These ‘futures’ contain, as an essential element, predictions of the changes of atmospheric temperatures at various heights above the planet and the various latitudes all the way from south pole to north pole.
The indisputable fact about these atmospheric temperature predictions is that if the pattern doesn’t happen, the model is wrong. Just as Fred won’t warm up if he isn’t surrounded by warm air, likewise the effects on the Earth of global warming cannot happen if the cause of the warming —the warm air—isn’t there.
So now we come to the graphs that clinch the matter. All global warming models predict some sort of developing ‘hotspot’ in the atmosphere above the tropics. Here is the graph for one of the models, but they all look roughly similar:
(F) Model predicts air above the tropics heats up. from the NIPCC Report p. 107
This picture shows the air from 75 degrees north to 75 degrees south (the equator in the middle) and up to 30 km above the Earth. We can think of this air pattern as corresponding to the pattern in Fred’s bedroom when Fred used a blanket: although the actual mechanism is different, something is ‘keeping the heat in’, so to speak. Just as we did with Fred in bed, we can compare reality with this picture. Is the heat in the real atmosphere doing what the model predicts? Here is the temperature trend in the real world:
(G) Real world trend develops no hotspot. from the NIPCC Report p. 106
What have we actually proved here? Well, proved, without possibility of error, nothing, of course: no question at all about the real world ever has a complete perfect proof as an answer, so don’t be misled if someone says the world still might be heating due to CO2 despite the absence of the warm spot that is supposed to do the warming. Of course anything might be happening; but how likely is it? Well how likely is it that Fred has a blanket, but the air around him is getting colder just as if he had no blanket, and yet Fred is warming up despite that? The two questions have the same answer: not very.
Yet surprisingly, some proponents of global warming alarmism actually resort to this very strategy. “True,” they say, “the hot spot isn’t developing. But that is because the heat is being stored up elsewhere—it’s “in the pipeline”—and one day it will burst forth with even greater severity and vengeance.”
What can we make of that claim? Well, thinking back to Fred again, it amounts to this: We use our temperature probe in Fred’s darkened bedroom and we see a pattern like that in (E) above, corresponding to no blanket: Fred should be freezing! But actually, the heat has all gone into Fred’s body, despite the complete absence of the hot air which is the mechanism for making it do so. In other words, Fred got warmer by disobeying the second law of thermodynamics—in other words, by magic. Likewise, if someone says heat is being secretly stored somewhere by global warming, despite the absence of the very mechanism that does the warming, they are saying global warming is happening by magic. That is the harsh truth of the matter.
One thing I have learned whilst studying the global warming question is that, like many other physical systems, the climate is constrained by limits that can be understood by any intelligent person willing to learn some simple physics. The ‘hotspot’ is one of them. Anyone talking down to you and telling you you have to take the word of some mythical ‘consensus’ of ‘experts’ is trying to hoodwink you.
Let’s say it’s a cold night and Fred climbs into bed:
(A) Fred in bed.
Will Fred use a blanket to keep warm? If so, the air will heat up close to Fred because his body warms the air and the blanket prevents it from moving away. On the other hand, as the night progresses, the air beyond the blanket will cool:
(B) With a blanket, the warm air collecting around Fred warms him up.
In the picture, the “+” signs show air that becomes warmer, and the “-” signs air that becomes cooler.
Now what if Fred (forgetful Fred) didn’t use a blanket? The warm air escapes and tends to rise (warm air being less dense than cold air):
(C) With no blanket, warm air escapes and Fred shivers.
Poor Fred gets colder as the night wears on. But now we come to the point of the exercise: How do we know whether Fred used, or did not use, a blanket?
“Easy,” you say: “Take a look!” But let’s suppose that Fred is a very light sleeper, we dare not put on the light, so there’s no way we can see if there’s a blanket. But—surprise!—we just happen to have an infra-red scanner that can tell us the temperature of the air at various spots throughout the room. Depending on whether Fred uses a blanket, the temperature change in the room follows one of the two characteristic patterns we saw above; so if we check where the air gets colder and where it gets warmer as the night wears on, we know, for a fact, whether or not Fred used a blanket, even without being able to see it. If Fred did use a blanket, our scanner should show results like this (note how we can’t see the blanket, but we can be sure that it is there):
(D) Warm air collects in a contained region, so there must be a blanket.
On the other hand, if he does not use a blanket, we will see the temperature change in a pattern something like this:
(E) Warm air escapes upwards, so we are sure there is no blanket.
Once again, there is no doubt at all what is going on. In science, nothing is absolutely certain, but depending on which temperature pattern develops, we can be very, very sure indeed of the answer to the question: Did Fred use a blanket?
Now we can turn to the global warming question, whether the Earth is surrounded by a ‘blanket’ of anthropogenic (human-generated) greenhouse gas stoking up the temperature of the planet. The physics of a real blanket (as with Fred in the fable above) and a gaseous ‘blanket’ around the Earth differ, but just the same, different heat dissipation (or retention) processes will result in different characteristic patterns of temperature change. Just as Fred will be surrounded by something roughly resembling one of two quite different patterns of air temperatures, so likewise will temperature changes around the Earth have a quite definite pattern, depending on which climate theory is right. Scientists whose paycheck does not depend on agreeing with global warming alarmism will all agree with this simple statement. It’s part of the basic skill of having a ‘nose’ for physics.
What, then, are our main competing climate theories? The IPCC’s reports are based on results from a collection of climate computer models; they have nothing else. These are simply computer programs that, in essence, contain a computerised version of the assumptions and beliefs of the climate modeller as to how the climate of the planet works. Whether these assumptions are well-founded is another question, but the key point is that whatever these assumptions may be, when the climate model is run, it generates its ‘predictions’ by calculation of hypothetical futures for the behaviour of the atmosphere. These ‘futures’ contain, as an essential element, predictions of the changes of atmospheric temperatures at various heights above the planet and the various latitudes all the way from south pole to north pole.
The indisputable fact about these atmospheric temperature predictions is that if the pattern doesn’t happen, the model is wrong. Just as Fred won’t warm up if he isn’t surrounded by warm air, likewise the effects on the Earth of global warming cannot happen if the cause of the warming —the warm air—isn’t there.
So now we come to the graphs that clinch the matter. All global warming models predict some sort of developing ‘hotspot’ in the atmosphere above the tropics. Here is the graph for one of the models, but they all look roughly similar:
(F) Model predicts air above the tropics heats up. from the NIPCC Report p. 107
This picture shows the air from 75 degrees north to 75 degrees south (the equator in the middle) and up to 30 km above the Earth. We can think of this air pattern as corresponding to the pattern in Fred’s bedroom when Fred used a blanket: although the actual mechanism is different, something is ‘keeping the heat in’, so to speak. Just as we did with Fred in bed, we can compare reality with this picture. Is the heat in the real atmosphere doing what the model predicts? Here is the temperature trend in the real world:
(G) Real world trend develops no hotspot. from the NIPCC Report p. 106
What have we actually proved here? Well, proved, without possibility of error, nothing, of course: no question at all about the real world ever has a complete perfect proof as an answer, so don’t be misled if someone says the world still might be heating due to CO2 despite the absence of the warm spot that is supposed to do the warming. Of course anything might be happening; but how likely is it? Well how likely is it that Fred has a blanket, but the air around him is getting colder just as if he had no blanket, and yet Fred is warming up despite that? The two questions have the same answer: not very.
Yet surprisingly, some proponents of global warming alarmism actually resort to this very strategy. “True,” they say, “the hot spot isn’t developing. But that is because the heat is being stored up elsewhere—it’s “in the pipeline”—and one day it will burst forth with even greater severity and vengeance.”
What can we make of that claim? Well, thinking back to Fred again, it amounts to this: We use our temperature probe in Fred’s darkened bedroom and we see a pattern like that in (E) above, corresponding to no blanket: Fred should be freezing! But actually, the heat has all gone into Fred’s body, despite the complete absence of the hot air which is the mechanism for making it do so. In other words, Fred got warmer by disobeying the second law of thermodynamics—in other words, by magic. Likewise, if someone says heat is being secretly stored somewhere by global warming, despite the absence of the very mechanism that does the warming, they are saying global warming is happening by magic. That is the harsh truth of the matter.
One thing I have learned whilst studying the global warming question is that, like many other physical systems, the climate is constrained by limits that can be understood by any intelligent person willing to learn some simple physics. The ‘hotspot’ is one of them. Anyone talking down to you and telling you you have to take the word of some mythical ‘consensus’ of ‘experts’ is trying to hoodwink you.
Kaboom (04:29:00) :
The death pollutant gas carbon dioxide is not a blanket (we don’t live in a greenhouse!!)
I just finished a bottle of some kind of carbonated drink called “Fernandez”, its damn tasty and you tell me that the CO2 in it is a deadly pollutant? OOOOOH MY GODDESS i am going to die.
BTW: Photons always travel at lightspeed, its that the keep bouncing into atoms and have to ask the way out again that slows them down.
I am a skeptic of AGW and do have a large problem with the IPCC’s work. So what I say here refers to the misuse of the two figures. I have seen these two figures so compared before. But, I am afraid the user overlooks the respective scales and thus makes too much regarding the differences. The modeled data is for a period of 41 years; the scale is C/41 years. The HadAT2 data is for C/decade, or C/10 years. Taking this into account then the hot spot in the modeled data reduces to a range of values from 0.25 C/10 years to 0.3 C/10 years. The HADAT2 data places the values from 0 C/10 years to .1 C/10 years. The ratio of these is ‘3’ for the upper end. So, even though there is a difference between modeled and observation we should be cautious in making too much out of this.
What if Fred’s blanket is infinitely thick?, then, and only then, greenhouse would be possible. (If Fred is infinitely robust, of course)
Stevo (12:15:57) : Happy to oblige.
OK, now to the core of my question. Say, I have a molecule of CO2 and it is in Earth’s atmosphere. Next our Sun sets a packet of energy traveling in Earth’s direction and some meters over my head energy meets molecule. Or not. So, much of the energy comes to Earth’s surface. Maybe it is reflected. Maybe it is absorbed. The absorption transforms the solar energy into molecular motion which gets measured as a temperature increase. Now the surface radiates from a lower temperature, than does the Sun, with a longer wavelength and the energy heads away from the surface – where it might have an encounter with a molecule of air, even, perhaps, CO2.
Usually, at about this point someone says “. . . and the atmosphere warms because CO2 acts like a blanket.”
Sorry, that won’t do. I want to know what happens next. Your answer should explain what CO2 does and why, and why N2 or O2 don’t do ‘this’, whatever ‘this’ is. In the end, whatever ‘this’ is, it is supposed to warm the atmosphere.
Your reliance on “The warming mechanism is pressure, not absorption.” – Seems to sidestep the entire notion of why GHGs are involved at all.
Then you have this: “And more greenhouse gases mean a thicker layer of IR-opaque ‘fog’,”
Do you actually mean there is a layer – I’ve seen diagrams with such layers – or do you favor a well dispersed mixture of molecules?
Is the atmospheric pressure at sea level greater at present than it was in the year before the industrial age began?
rbateman,
It took you an hour to read that?
Well, ok, here’s a faster explanation. Greenhouses gases aren’t a blanket, they’re a refrigerator. Kitchen refrigerators pump heat from the inside to the outside. The one in the atmosphere cools the top of the atmosphere and pumps the heat down to the surface. And because the thermostat is positioned half way up the fridge, the bottom is warmer than expected given the number on the dial. That extra warminess is called the greenhouse effect.
Fred’s blanket is assumed by the models to act as a diode. The energy comes in, but the heat (IR) can’t get back out.
Fred is a good model. The Earth likewise is heated internally by tidal forces of Sun & Moon gravitational tug-of-war acting in equal force by way of distance scale and in constant state of vector change.
The models predicted increased heat retention assuming that Fred’s blanket is 100% effective in thier calculations, and blew off any change in the thermostat that heats Fred’s room at night. The only thing wrong with Fred is that his diet is not 100% constant.
The amount of heat coming from the Sun is not constant, and neither is the atmosphere’s retention rate linear as regards the trace gas CO2. So they changed thier models. They still have it 95% wrong.
I could say the same thing about the Sun & Solar System’s evironment as regards the Galaxy, but I’ll wait.
We can do an experiment actually. Put 350ppm of c02 in a chamber and 600ppm in an identical chamber. Subject them to the same heat source for 30 minutes at 30C.
According to the AGW advocates, the 600ppm ought to be 34C whilst the 350ppm chamber would be constant 30C, in theory. It raises the question: Where did this extra 4C come from?
Stevo: Ijust had an email from teh Met Office here in the UK in response to a question as to why temperatures plummetted during the solar eclipse. They categorically replied that “C02 doesn’t retain heat. It intercepts and transfers heat to the atmosphere” Therefore, despite c02 being the great climate driver, it tells the heat to go elsewhere, since c02 doesn’t seem to like absorbing heat.
Fill a closed test tube with a known amount of CO2 gas, heat it up using an infrarred bulb, take the time it takes to cool down (in nanoseconds of course).
Stevo (13:52:44) :
rbateman,
It took you an hour to read that?
It will take an hour to EXPLAIN that to Fred the Citizen, and you have about 5 minutes top, after which all subsequent explanation will fly over the head of Fred.
Fred doesn’t do heiroglyphic scientific paper reading.
Fred will stop you after 30 seconds for the definitions of words never heard before.
At that point, it’s all downhill.
Couple of spins in Fred’s head over a highly confusing picture and you’re done.
Fred will excuse himself.
I guess i’ll be adding c02 to my bedroom if my heating breaks down this winter…
or better still, just open the window and let it diffuse in from the cool air outside
John F. Hultquist,
The photon hits the solid surface and is absorbed. It’s actually irrelevant how the heat escapes to the middle/upper atmosphere – some does so by IR radiation, some by convection, some by evaporating water from the surface (like sweating cools you). The only thing that matters is that because greenhouse gases can absorb and emit IR, that at least some of the emission to space is from altitude.
The reason why H2O and CO2 absorb/emit is that their molecules are asymmetrical. Some bits look different to other bits, and in particular have a different electrical charge, which means electromagnetic waves have something to ‘grab on to’. N2 and O2 are ‘all the same’, so the forces cancel out exactly.
It would in fact be possible to have a greenhouse effect without any greenhouse gases at all. Imagine a fictional alien planet that has a very thick Nitrogen atmosphere and a high level layer of dusty clouds, that absorb and re-emit nearly all of the light of the sun. The cloud layer settles out at the equilibrium temperature, such that it emits exactly as much heat as the planet absorbs, and just enough light gets through the clouds, reaching the surface, to drive convection. Then as gas descends from the warm cloud level down to the surface, it is compressed and gets hot. And then as it rises again it expands and cools down. If the atmosphere is thick enough, the surface could be intensely hot. A 50 km thick atmosphere with a 10 C/km lapse rate would be 500 C hotter than the clouds above. And with not a greenhouse gas in sight.
All that matters is that some of the emission is from above the surface, so the average altitude of emission is greater than zero; and that enough energy reaches the surface to drive convection. Without convection, the temperature gradient reverses, with warm air on top of cold, and there is no exchange between layers to drive the changes in temperature.
The fundamental reason they matter in the Earth’s atmosphere is that they change the average height of emission – moving the ‘thermostat’ upwards. All that matters is that they emit. Absorption is just an equivalent physical property. But even if you could invent some impossible material that emitted without absorbing, the heat would still rise by convection, evaporation or even conduction to the emitting layer and it would still show the same effect.
Nearly all of the emission to space comes from the bottom 8 km, with a nearly uniform spread over that altitude, so some of it comes from colder air and some from warmer – and of course there’s some direct from the surface, which is what the satellites pick up. That’s simply because that’s where the water vapour is. It evaporates from the surface, and condenses out when it gets too cold, so that above a certain altitude the air is intensely dry. If you want the exact profile, see Manabe and Strickler, J. Atmos. Sci. 21:p373 (1964).
roddy.baird (05:27:49) :
“Nonetheless I find the idea that the atmosphere heats the ocean a little counter intuitive.”
Roddy, as I understand it if something is warmer than something else then given the opportunity heat will travel downhill, and heat will not distinguish between solid, liquid or gas. As an example in the UK we are subject to about 5 different types of air mass (excuse if you know already), and is either dry, wet, hot, warm cold etc. and all because that air has passed over something dry, wet, hot, etc. etc. It might not be much, but if air passes over water that is cooler than itself then the air will become a little cooler and the water a little warmer. Of course once that air gets here then depending on prevailing conditions the land will either add or subtract heat or moisture. I haven’t forgotten the sun. It’s just for us in the UK to have a nice day down the beach we need the air to come from somewhere warm and dry, and not too fast, and then the sun can get to work.
“no matter how good the blanket, a fart still smells like a fart”
You know the honeymoon’s over when the husband pulls the blanket over his spouse’s head after he’s farted in bed.
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Stevo (12:15:57) :
This is important. The surface is not warmer because heat is “trapped”. The warming mechanism is pressure, not absorption. And more greenhouse gases mean a thicker layer of IR-opaque ‘fog’, a higher average emission altitude, and therefore a greater pressure difference between this altitude and the surface.
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OK, I’ll bite. So you add 200 ppm to the atmosphere. The average emission altitude goes up. So what? The extra 200 ppm of CO2 won’t add any significant pressure due to the extra gas. If you are saying the extra CO2 will heat the air and thereby increase the pressure, OK. So you add the CO2, increase the pressure, the air get hotter and re-equilibrates. That is, the heat caused by the increase in pressure dissipates and the air cools off. For example, if I turn on my compressed air machine. It gets hot as the pressure goes up. But after the pressure ceases to increase, it cools off again.
Someone could repeat the Wood experiment: http://neighbors.denverpost.com/blog.php/2009/02/04/greenhouse-theory-disproved-a-century-ago/
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Stevo (14:39:09) :
All that matters is that some of the emission is from above the surface, so the average altitude of emission is greater than zero; and that enough energy reaches the surface to drive convection. Without convection, the temperature gradient reverses, with warm air on top of cold, and there is no exchange between layers to drive the changes in temperature.
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Why doesn’t the convection upwards take away as much heat as was deposited by the sinking gas?
OK, this is what I do not understand and I would appreciate someone explaining for me.
Question 1. There are numerous graphs, pictures out there , related to GW that depict temperature anomalies. So we have somewhere up in the atmosphere that is 2C warmer than it used to be. For a standard atmosphere of 15C lets assume at around 10,000ft it has warmed from a supposed usual of 0C to 2C. The question is can this extra heat warm the surface?
Question 2. CO2 is considered to have a greater affect (heating wise) at altitude. Considering CO2 is distributed evenly at around 360 ppm what consideration is given to the actual amount per volume? e.g at 10,000 there is a third less atmosphere for a given volume. So whereas at sea level there might be 360 CO2 molecules in a given volume, at 10,000ft there is only 240 CO2 molecules for the same volume, and at 35,000ft there is a measly 1/5 or around 70 CO2 molecules.
“”” Stevo (14:39:09) :
John F. Hultquist,
The photon hits the solid surface and is absorbed. It’s actually irrelevant how the heat escapes to the middle/upper atmosphere – some does so by IR radiation, some by convection, some by evaporating water from the surface (like sweating cools you). The only thing that matters is that because greenhouse gases can absorb and emit IR, that at least some of the emission to space is from altitude.
The reason why H2O and CO2 absorb/emit is that their molecules are asymmetrical. Some bits look different to other bits, and in particular have a different electrical charge, which means electromagnetic waves have something to ‘grab on to’. N2 and O2 are ‘all the same’, so the forces cancel out exactly. “””
So just what is it about CO2; and how about CH4, that is assymmetrical. Explain how this assymetry is any different from the assymetry of O2 and N2.
So a sphere is symmetrical; but what else is ? And that too is irrelevent since spheres do not exist anywhere in the universe.
Out of interest and related to the temperature cross sections. I watched a DVD of Concorde on a round the world trip. As Concorde crossed the Pacific it was pointed out that Concorde was able to go further and higher because of the colder equatorial air at altitude. It was not a surprise. It was expected and planned for.
Where the IPCC is in error is on the 4th power lapse of infrared radiative forcing. The 1st power of course, is the solar energy reaching the earth which c02 is invisible to. The 2ns is re-radiation to the tropopause (1-3% of the original energy budget) The 4th power is the re-radiation back to the earth from the tropopause downwards and upwards – absorbed radiation is re-emitted bi directionally – so we can assume that 50% of withheld radiation goes back into space – In other words, thermal re-emission beyond the tropopause – whilst the other 50% does in fact go back to the earth. From 1-4 there is a huge energy loss. No additional energy is re-introduced during this process, so it can be assumed that the coefficient of solar energy is the dominant factor. The IPCC assumes that the ratio isn’t 1:1 even but entirely downwards, which is the first fundamental mistake. So when warming projections looked exagerrated, they assumed that it was a cooling effect from aerosols. What they are also ignoring is the strong water vapour feedback – it also witholds heat at 15Mc’s and many other wavelengths – far more than c02, and given that from the tropopause to the earth is where water vapour resides, it effectively means that there is less radiation for c02 to absorb. Efectively, the water vapour feedback neutralises the c02 feedback, and climatically they are both feedbacks and not forcings, and are dependent on atmospheric temperatures. This is the case for all c02, and not just the 3% anthropogenic
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Stevo (12:15:57) :
This is important. The surface is not warmer because heat is “trapped”. The warming mechanism is pressure, not absorption. And more greenhouse gases mean a thicker layer of IR-opaque ‘fog’, a higher average emission altitude, and therefore a greater pressure difference between this altitude and the surface.
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Stevo – what you have said is interesting. If you would suffer one more questsion. I thought sunlight mostly passed through the atmosphere and was absorbed by the surface of the Earth, including the oceans – even there it eventually goes dark at some depth. So the sunlight is absorbed and heats the Earth. I thought that is why the surface of the Earth is hot. Again, why do you say it is pressure?
Time to refer to my highly relevant article here:
http://climaterealists.com/index.php?id=1562&linkbox=true
“Greenhouse Confusion Resolved.”
This essentially shreds the notion of positive feedbacks. Conversely, it suggests where the next round of research should focus, namely, understanding negative feedbacks.