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During the past several months there have been various, unpublished studies circulating around the blogosphere and elsewhere claiming that the “greenhouse effect” cannot warm the Earth’s atmosphere.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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Misconception is a failed conception, a natural or an induced abortion. Is your theory the equivalent of the “Day After pill”? 🙂
Phil. says:
July 23, 2010 at 12:42 pm
“Suppose you have an isolated black ball which you heat so that it eventually equilibrates at a certain temperature, introduce another ball nearby at a lower temperature, the hotter one will get hotter (as will the cooler).”
Are you sure about this, Phil? That the hottest will be hotter? I allways believed that this is exactly what was impossible, according to the 2’nd law….because if it got hotter…then heat has gone from colder to hotter….. or is this Trenberts hidden heat?
Monckton: how much warming a given increase in CO2 concentration will be expected to cause (around a third of what the IPCC projects
.
Climate Sensitivity Reconsidered
http://www.aps.org/units/fps/newsletters/200807/monckton.cfm
.
Real Climate: Once more unto the bray
http://www.realclimate.org/index.php/archives/2008/07/once-more-unto-the-bray/
.
The APS and global warming: What were they thinking?
http://duoquartuncia.blogspot.com/2008/07/aps-and-global-warming-what-were-they.html
BTW:
Why forests are so fresh:
Examples of Endothermic and Exothermic Processes
Photosynthesis is an example of an endothermic chemical reaction. In this process, plants use the energy from the sun to convert carbon dioxide and water into glucose and oxygen. This reaction requires 15MJ of energy (sunlight) for every kilogram of glucose that is produced:
sunlight + 6CO2(g) + H2O(l) = C6H12O6(aq) + 6O2(g)
Dr. Ferenc Miskolczi says in his paper (Miskolczi, Ferenc M. 2007. “Greenhouse Effect in Semi-Transparent Planetary Atmospheres.” Időjárás 111, 1-40) that water vapor and CO2 are in permanent equilibrium, and that for the past 61 years there has been no global warming, whatsoever, as a result of CO2 increases. For the last 3 years, as far as I know, no one has been able to prove him wrong.
Talking of greenhouse gases ( GHG ) assumes that it is the chemistry of the gases that matters. O2 is OK, CO2 is a GHG, and therefore bad.
The temperature of the earth’s atmosphere depends on the kinetic, translational energy of all the gas molecules in it, mainly oxygen and nitrogen.
1. THE “GREENHOUSE EFFECT”
AS A FUNCTION OF ATMOSPHERIC MASS
http://ruby.fgcu.edu/courses/twimberley/EnviroPhilo/FunctionOfMass.pdf
planet pressure Atmosphere effect Atmosphere gas
mars low low CO2
earth medium medium O2and N2
venus high high CO2
The surface temperature of planet atmospheres depends on the pressure not the type of gas.
There is similar effect on Jupiter and other planets made of hydrogen and helium
The atmosphere is physics not chemistry
Scott Basinger says:
July 23, 2010 at 2:31 pm (Edit)
The “greenhouse gases” heat the earth’s surface up approximately 35°C higher than it would be otherwise.”
No they don’t. They slow the rate of cooling.
Please don’t try to say that ‘this is the same thing’.
Ryan writes:
“What AGW proponents are saying is that we have, in CO2, a translucent panel above our heads (i.e. it absorbs light). According to AGW proponents, if we put more and more translucent panels above our heads the area beneath the translucent panels will get brighter and brighter.”
Let me put that a bit differently. From the posts we have seen today, especially including Pielke, Sr’s article, CO2 in the atmosphere can be treated as a magnifyer of the Sun’s energy, in appropriate bandwidths, of course. From that, it follows that the effects of CO2 would necessarily parallel changes in the sun’s energy output.
Aside from the point above, would someone who knows the math undertake the exercise of treating CO2 as a magnifyer of the sun’s output? I think it would be greatly illuminating.
Joss writes:
“That’s plausible. But if it is that simple, why not laying down the equations and publish a much needed paper?”
This is what is so frustrating about attempting to discuss matters with climate scientists, both warmists and deniers. No one introduces actual hypotheses about phenomena in the environment that can be shown to be true or false at some future time. All discussions are about unchallenged principles or the sort of thing that happens in the laboratory. Does no one have a genuine hypothesis about behavior of the atmosphere under the influence of CO2?
You forgot point 4 i.e. will increased co2 lead to a runaway warming of the planet? That is the most important question for me and so far all I get are caveats. (Point 2 kind of hited at it though)
The basic points made by Ben Herman and Roger A. Pielke Sr. are quite valid as far as they go. Also the comments by Monckton of Brenchley put the whole issue in correct perspective. The Earth is a particularly complex case with oceans, clouds, water vapor and the main gases of the atmosphere. However it should be remembered that water vapor and clouds constitute the main part of the greenhouse effect on Earth.
Mars, mainly consisting of CO2 at a much lower pressure is a totally different case. The first point to make about Mars is that the adiabatic lapse rate (=g/Cp) is less than 1/2 that of Earth due to lower gravity dominating the slightly lower Cp. In addition, lack of water vapor and clouds decrease the absorption of long wave radiation compared to Earth. It has also been observed on Earth and Venus that there is a minimum pressure where lapse rate assumptions break down (about 1/10 bar), and the lapse rate becomes smaller than at the higher pressures. This may be due to the solar wind and other external forcing being more significant. The result is that a lower lapse rate would be expected for Mars, and is in fact seen.
Venus is different from both Earth and Mars. There is a mostly CO2 atmosphere that is both very massive and high, and a solid cloud layer very near the location of outgoing radiation. It is likely that the cloud layer both absorbs most of the incoming solar radiation that is not reflected, and emits most of the long wave outgoing radiation. Only a very small fraction of the sunlight reaches and is absorbed at the surface. The atmosphere is also extremely dense (about 91 bar). The absorption by the CO2 near the surface is so high that back radiation to the surface is also very large and net radiation heat transfer is very small. The net result is that the hot surface and hot lower layer of the Venus atmosphere are mainly maintained by the flowing atmosphere (convection and turbulent mixing), not solar heating of the surface or radiation heat transfer. The flow that maintains the high temperature is that portion of the atmosphere that absorbs most of the sunlight, and is adiabatically compressed as it is convected down and mixed through the atmosphere. The lapse rate, which is in this case the adiabatic lapse rate, is the result of the increased temperature from conversion of gravitational potential energy to kinetic energy as the gas goes down. It is almost exactly the value expected from g/Cp for CO2 at the high temperatures. One could say it is the combination of high pressure, tall atmosphere, and greenhouse gases that result in the very high ground temperature on Venus.
Getting back to Earth, as the greenhouse gas concentration increases over the present level, due mainly to CO2, the only way the temperature would increase (assuming water vapor feedback is not a large factor, and it does not seem to be) would be for the altitude of the effective outgoing radiation to increase (the lapse rate would not increase). Since the high altitude pressure drops very rapidly with increasing altitude, the increase is limited to a few degrees. However, that is assuming the water vapor does not become a significant fraction of the total mass of the atmosphere. The possible water vapor fraction is limited for any reasonable temperature, so this should not be an issue.
A final parting point. The wet lapse rate is smaller than the dry lapse rate. The greater the water vapor content, the smaller this wet lapse rate becomes. As the water vapor content became more significant, the lapse rate would actually DROP. The result would be a cooling at lower levels even with a modest raising of the level of radiation out. The problem is very complicated, and there is no realistic chance of greenhouse runaway or heating more that a few degrees.
From what I remember any atom or molecule when it’s electron have a change in velocity (acceleration/deceleration) will always radiate no matter what type of particle it is of where the change in velocity came from (collisions, vibrations, etc.). Is this when two O2 and/or N2 also radiate when they collide? I think it in the microwave so weaker photons but there are many magnitudes more of those molecules within the atmosphere than CO2 which should compensate. WUWT? Never have seen it mentioned.
Boy, did Ben Herman and Roger A. Pielke Sr. ever leave gapping holes in their explanation !! Just read the comments above. Where are all of the inconvenient and lacking-complete-understanding factors which should have at least been mentioned? Come on climatologist, you can do better than that. Give us some real info, don’t worry, you won’t go over most heads here.
I’ve always wondered if the equation that comes up with 33 degrees of greenhouse effect took into account that space really isn’t absolute zero – if I recall correctly it’s 3 or so K. Not that it really matters, just curious if anyone knew
Maybe instead of “greenhouse” gasses we could call them “blanket” gasses, for that is what they do.
‘From what I remember any atom or molecule when it’s electron have a change in velocity (acceleration/deceleration) will always radiate no matter what type of particle it is of where the change in velocity came from (collisions, vibrations, etc.). Is this when two O2 and/or N2 also radiate when they collide? I think it in the microwave so weaker photons but there are many magnitudes more of those molecules within the atmosphere than CO2 which should compensate. WUWT? Never have seen it mentioned.
Boy, did Ben Herman and Roger A. Pielke Sr. ever leave gapping holes in their explanation !! Just read the comments above. Where are all of the inconvenient and lacking-complete-understanding factors which should have at least been mentioned? Come on climatologist, you can do better than that. Give us some real info, don’t worry, you won’t go over most heads here.’
Too true wayne, too true.
It is almost like a propaganda post.
we want real answers to the unaswered questions, not to be patronised in a – don’t be a denier – kind of way.
We know it warms
HOW MUCH ???????
Maybe I’m missing something, but of course I do miss a lot, but why does everyone use the sun as a constant when its output is highly variable on a day to day basis, month to month, year to year, cycle to cycle? Is it like gravitational pull and push which is used as a constant, in junior high lol, for being conveniently abstract rather than accuracy and detailed?
And using CO2 as some form of a starting point in the whole so called green house effect is moot since nobody frakking knows which gas molecule exhibit the main secondary forcing or what ever. What does CO2 mean if water vapor is first, or heh argon? What would happen to the temperature, in reality, if we could switch co2 for argon, or oxygen, or nitrogen? After all if we remove the “overhead” of co2 something will take its place, especially if you believe that the atmosphere only can consist of 100% of stuff at 1 bar and 1 bar at sea level is an absolute constant.
If the earth’s atmosphere really worked like a green house effect you’d be able to remove the sun and exchange it for an artificial non-heating light source, what with it gets its supposed heating from the ground up rather then from the sun. lol try convincing people of a real green house effect when it is 40 below. The so called green house effect is naught but a self made statistical phenomenon.
If the black body radiation is the primary way by which energy is emitted and we know it is proportional to the FOURTH power of temperature. It seems clear the energy budget must depend on the distribution of heat on the planet. So any change in the movement of air or seawater can change the radiation budget. So some of the recent warming could have been caused by a transfer of heat from the tropics to the arctic.
Steven Mosher says:
July 23, 2010 at 10:50 am
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.
————————-
Steve,
Hi, I loved your book : )
Overall, your comment rings true to me with two exceptions:
Exception #1 – in your leading paragraph you show a significant concern about the negative things the “warmists” (your word not mine) might think about some of the GHG effect (or lack of effect) comments by individuals on this active and long thread. In an open society like this wonderful venue Anthony has created, people will do naturally what the commenters are doing on this thread. Limiting comments here because of concern about what the “warmists” think will tend to make for a much more limited participation and there would eventually be less learning going on about very important things. The key is learning.
Exception #2 – you also say “C02 will warm the planet, up to limit”. Ben Herman and Roger A. Pielke Sr give us an introductory tutorial on “the greenhouse effect”, but it is simplistic by their own intention to illustrate fundamental points to try to teach people who they think are missing the physics fundamentals about “the greenhouse effect”. They are to be commended for that and I admire them for that. In their simplistic example they show “GHGs, all other things being constant, will warm the planet”. But when adding in all the very high level complexity of our earth’s systems (which cannot be any farther from constant), however, there is no automatic assurance that about the statement that “C02 will warm the planet, up to limit”. It may try to, but does it when combined with everything else? I think so, but think also that we have hardly started the climate science homework to be convincing about it.
Bless Anthony and the WUWT team.
John
Roger Clague says:
July 23, 2010 at 2:49 pm
http://ruby.fgcu.edu/courses/twimberley/EnviroPhilo/FunctionOfMass.pdf
Roger, I read that paper. Difficult to debunk, I would say.
“”” NickB. says:
July 23, 2010 at 3:28 pm
I’ve always wondered if the equation that comes up with 33 degrees of greenhouse effect took into account that space really isn’t absolute zero – if I recall correctly it’s 3 or so K. Not that it really matters, just curious if anyone knew. “””
Has no effect. Remember that objects are limited to radiating sigma.T^4 W/m^2 max (thermally); so just how much radiation do you think you are going to receive from a 3 Kelvin Black Body radiator ?
It is weak enough that it takes a major radio telescope antenna to even detect it in the noise. But a good question.
George E Smith’s response (10:58) to Jeff’ comment is, I believe, an example of what I perceive as the need when discussing energy flow and temperature to carefully define terms. I ask the readers of this post: (a) are the following two statements equivalent; and (b) if not, which statement, if either, is the commonly accepted definition of “cooling”.
(1) An object is “cooling” if the net energy flow is away from the object.
(2) An object is “cooling” if its temperature is decreasing.
“”” kwik says:
July 23, 2010 at 4:10 pm
Roger Clague says:
July 23, 2010 at 2:49 pm
http://ruby.fgcu.edu/courses/twimberley/EnviroPhilo/FunctionOfMass.pdf
Roger, I read that paper. Difficult to debunk, I would say. “””
You may be right on that debunk being difficult; I would say it is just about pure bunk.
Steven Mosher says:
July 23, 2010 at 10:50 am
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.
I’m sorry to see the warmists have successfully brainwashed Mosher into believing co2 warms the planet.
The Sun warms the planet. Co2 does not and cannot warm the planet. As Pielke senior correctly points out, GHG’s (mostly water vapour) can slow down the rate of cooling of the planet. Slowing down the rate of cooling is not the same thing as being able to warm something up.
Can my blanket warm my bed up before I get in it Mosh?
Reed Coray says:
July 23, 2010 at 4:13 pm
George E Smith’s response (10:58) to Jeff’ comment is, I believe, an example of what I perceive as the need when discussing energy flow and temperature to carefully define terms. I ask the readers of this post: (a) are the following two statements equivalent; and (b) if not, which statement, if either, is the commonly accepted definition of “cooling”.
(1) An object is “cooling” if the net energy flow is away from the object.
(2) An object is “cooling” if its temperature is decreasing.
—————-
Reed Coray ,
My wife tells me it is better to grab the tail of the dragon (lung in chinese), than to look in its mouth.
John
tallbloke says:
July 23, 2010 at 4:23 pm
The Sun warms the planet. Co2 does not and cannot warm the planet. As Pielke senior correctly points out, GHG’s (mostly water vapour) can slow down the rate of cooling of the planet. Slowing down the rate of cooling is not the same thing as being able to warm something up.
Can my blanket warm my bed up before I get in it Mosh?
——————–
tallbloke,
Ahhh heck, I wish I could have said that blanket thing. : )
John