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During the past several months there have been various, unpublished studies circulating around the blogosphere and elsewhere claiming that the “greenhouse effect” cannot warm the Earth’s atmosphere.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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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.
See:
http://www.scribd.com/doc/28018819/Greenhouse-Niels-Bohr
No CO2=No life on earth=No YOU.
BTW: CO2 it is not black, ya know, it’s what you exhale (900 grams a day)and plants breathe.
John Prendergast says:
July 23, 2010 at 9:20 am
“[…]cooler fuller spectrum radiating nitrogen and oxygen molecules. The very slightly heated Oxygen and Nitrogen molecules radiate more energy to space than they did before. ”
One objection, John: O2 and N2 don’t radiate in the LWIR range. What they can do is rise, give the heat back to CO2 molecules higher up in the atmosphere via collisions, and CO2 is a good radiator in the LWIR range – namely in its absorption band. That is why CO2 and water vapor act as coolants in the stratosphere because these molecules are best suited to radiate LWIR to space.
I disagree completely with the 3rd and 4th paragraphs because they refer to a step change in absorption and not the resulting steady state condition after the system returns to equilibrium! The temperature of theEarth is controlled by the radiation received from the sun. If that radiation is held constant, the changes in the CO2 concentration will not deduce the energy out, only slow the transit time temporarily until the new equilibrium condition is achieved. Energy in was balanced with the energy out prior to the step change and if the energy in does not change, the energy out will again balance the energy in at the new equilibrium level. The only change is the temporary change to the radiation transit time.
Mr. Juraj V;
Are you saying there is more CO2 on Mars than on Earth, yet there is no discernible ‘greenhouse warming’ on Mars? Yikes!
From those very handy links,
Mars atmosphere is ~2.5 x 10**16 kg, @ur momisugly950,000 ppm CO2, yes?
Earth atmosphere is ~5 x 10**18kg, @ur momisugly 400ppm CO2.
This seems to be a very potent issue for the greenhouse advocates.
Maybe RC can answer this one.
RR
What is patently obvious is that there are too many processes going on in the atmosphere, including daytime/nighttime effects, seasonal effects, land versus ocean effects, conduction, convection, radiation etc etc for simple explanations to answer the question. It is because “climate scientists” try to oversimplify what is a very comples process and include “back-radiation” that non-experts in thermodynamics get very confused.
Perhaps it is the purpose of “climate scientists” to spread confusion because they do not understand it themselves.
Explaining misconceptions on “The Greenhouse Effect”
Posted on July 23, 2010 by Anthony Watts
Guest post By Ben Herman and Roger A. Pielke Sr.
“[…]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.”
Wait. If a cooling rate decreases, but, as you say, the overall radiation emitted by the planet stays the same, this means that the heat transport becomes slower. This is in line with my CO2 fog argument.
BUT, if the TRANSPORT RATE decreases, this will lead to an increase in “trapped heat” only as long as the transport rate keeps decreasing. IOW, the temperature anomaly must be the first derivative of the CO2 increase as recognized by Beenstock and Reingewertz
(in
http://economics.huji.ac.il/facultye/beenstock/Nature_Paper091209.pdf
)
and as predicted by Miskolczi’s theory.
So i guess we have a new consensus here even though we approach the argument from different angles.
DirkH says:
July 23, 2010 at 9:40 am
“IOW, the temperature anomaly must be the first derivative of the CO2 increase ”
Correction : “the temperature anomaly must be the first derivative of the CO2 concentration”
We must be nit-picky here.
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.
Some comments:
1. The weight of the atmosphere adds heats. PV=nRT. STP indicates without “GHE” temperature is 273 K. So “GHE” can account for 15 K at most.
2. The second law is about the increase of entropy. dS = dQ/T. You seem to be saying entropy can decrease. Please be clearer. Every exchange of a IR photon must increase entropy and thereby not allowing an increase in temperature.
3. If you are going to use blackbody radiation then include Wein’s Law. T = 3000/micro. The absorbtion line for CO2 is 15 micro. That is a temperature of 200 K. We live is a 300 K world. Any IR absorbed by a molecule of CO2 would be at the temperature energy level of 200 K. How does this heat anything? Further, let’s be clear black body is for a two dimensional cavity. The soil, rocks, etc absorb energy down to depth which is a violation of the use of black body theory.
4. All atmospheric gases dissipate heat. None add heat on there own. Adding CO2 in my living room will not increase the temperture as long as my heater puts out the same heat. CO2 in not an insulator.
5. O2 or N2 that absorbed conducted heat or convected heat from the ground will not be effected by anything a CO2 molecule does having absorbed an IR photon.
Thank you for the post.
Omitted is the fact that the overwhelming greenhouse effect is caused by water vapor and not CO2.
I do not know of any serious student of climate study refuting the fact that water vapor literally blankets the planet and keeps it warm during nighttime.
This fact is evident whenever cloud cover at night blankets us even in colder weather.
Everyone who is alive recognizes that fact and it has never been in any serious dispute.
A crystal clear night cools more rapidly than a cloudy one. What is always lost on the warmest, and apparently the authors of this piece, is that CO2 remains relatively constant whether or not the night sky is cloudy or clear.
If CO2 were a dominate greenhouse gas, then every night would remain warm regardless of cloud cover.
Thus endeth the obvious. Why not point it out?
Ben Herman and Roger A. Pielke Sr: NODC Ocean heat content (OHC) data shows no sign of the effects from a rise in anthropogenic greenhouse gases. Tropical and southern hemisphere OHC show flat to declining trends that are occassionally shifted up by multiyear La Nina events. See:
http://bobtisdale.blogspot.com/2009/09/enso-dominates-nodc-ocean-heat-content.html
North Pacific OHC declined until the late 1980s, then shifted upwards with a change in the NPI. Refer to:
http://bobtisdale.blogspot.com/2009/12/north-pacific-ocean-heat-content-shift.html
And North Atlantic OHC is impacted by AMO/AMOC, sea level pressure and ENSO. See:
http://bobtisdale.blogspot.com/2009/10/north-atlantic-ocean-heat-content-0-700.html
Vince Causey says:
July 23, 2010 at 8:15 am
“Good article Dr. Pielke. It is unfortunate that this needs saying at all, but I fear the infamous G&T paper has done a bit of damage to the credibility of sceptical science.”
Not at all! It is the same argument as formulated by Prof. Claes Johnson and classical thermodynamics! It is just that we mere mortals often have a hard time following the physicists because they tend to make rather large steps in their arguments. It’s not a contradiction at all.
Trouble with carbon dioxide greenhouse effect is that it requires carbon dioxide to absorb infrared radiation and thereby get warm. This simply does not happen because the infrared band of the atmosphere is saturated and no further additions of carbon dioxide to air can change the already-existing greenhouse effect. This follows from the empirical observation based on NOAA’s weather balloon database that the global average annual infrared optical thickness of the atmosphere has been unchanged for 61 years, with a value of 1.87. This means that constant addition of carbon dioxide to the atmosphere for the last 61 years has not had any influence on the transparency of the atmosphere in the infrared or the optical thickness would have increased. And it didn’t. See Ferenc Miskolczi E&E 21(4):243-262 (2010). His is the first determination of the actual optical thickness of the atmosphere in the IR despite the billions spent on “climate research” by “climatologists” who spew out thousands of “peer reviewed” papers every year.
1. It’s kind of sad that Pielke needs to put this kind of thing forward and that hoi polloi are/were/continue to be so wishful thinking as to believe the greenhouse effect can not exist or the like.
2. There are a lot of good insights from nuclear reactor design that are useful in giving insights into why greenhouse effect occurs. Things like understanding heat transfer accross plates of multiple cladding content. Things like how a material may be non-absorbing of fast neutrons, but absorbing of thermal neutrons. how water can act as a “reflector” despite isotropic nature of the liquid itself, how power can remain the same, but centerline temp change as a result of gradient across the plate. Etc. etc.
“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. ”
Whoa! Big logical leap right there. The atmosphere may on average warm up. That does NOT mean that the ground warms up.
The absorbtion could be in the upper layers of the atmosphere leaving less energy to reach the ground. This will be particularly true if the angle of incidence of incoming radiation is such that the energy reaching the ground has had to travel through a great deal of atmosphere to reach the ground – since much of the warming of the (upper) atmosphere will in such cases occur further south.
Imagine a duvet touching your body – the inner layers of the duvet tend to get as warm as your skin temperature but the outer layers do not, and neither do the parts of the duvet not in contact with your skin.
And all this is before we get into the complexities of energy being absorbed by evaporation creating cloud cover and therefore less incident radiation reaching the ground, in the manner of a giant air-conditioning system.
Thank Dr. Pielke,
One of the difficulties the sceptical community has in making any headway is the large collection of nonsense that certain people insist upon. Luckily, Christy, Spenser, Lindzen, Pielke, Monkton all rightly understand that the key scientific questions is
How much warming.
GHGs will not cool the planet.
“When absorbing gases are added to the atmosphere, more of emitted radiation from the ground is absorbed by the atmosphere”
Can I just point out the CO2 is not just an absorbing gas, it is also an emitting gas.
A gas which absorbs at a particularly frequency is also a gas which emits at that frequency (at least when that frequency is near black body temperature).
Adding CO2 to the atmosphere therefore can also tend to make it cool down by creating a pathway for heat to be emitted by the CO2 if the CO2. This is basic physics and it is about time the cooling effects of CO2 were more widely known.
Wow, this is a popular thread!
As few are likely to connect my first post back to Juraj V insightful comment,
I herewith try to make a self-contained post.
What about the application of ‘greenhouse gas’ theory to Mars?
The (thin) Martian atmosphere is >95% CO2.
Unless I’ve blown the math, Mars atmosphere has much more (total) CO2 enveloping Mars than our Earth enjoys.
Yet the atmospheric temperature of Mars is the same as the BlackBody temperature, at 210K.
So, it seems that ‘greenhouse gas’ theory should apply with equal vigor to warm Mars as to more complex planets like Earth.
Is it wrong to expect that a planet with more total CO2 than Earth would have such a negligible ‘warming’ by all of that CO2?
Perhaps Dr. P will run the GG math on this nice clean example planet, which lacks the complexity of oceans, clouds and highly variable albedo feedbacks.
TIA
RR
Very nice and straightforward article. Easy to understand. I’m certain that despite the clarity and scientific rigor of this and countless other articles, a certain class of skeptics will continue to spew forth their own unfounded nonsense.
Steven Mosher says:
July 23, 2010 at 9:57 am
“[…]GHGs will not cool the planet.”
CO2 in upper atmospheric layers does cool the planet.
“The planet’s temperature is regulated by the thin upper layers where radiation does escape easily into space. Adding more greenhouse gas there will change the balance.”
from:
http://www.aip.org/history/climate/co2.htm
See also:
“Earth’s upper atmosphere cooling dramatically ”
http://www.msnbc.msn.com/id/34479085/
Dr. Pielke et al, do you disagree with these numbers;
http://www.geocraft.com/WVFossils/greenhouse_data.html
It would be nice to know whether you agree. Because if you do, we can further agree that the effect from human induced CO2 can only be insignificant noise in the big picture.
Enneagram says:
July 23, 2010 at 9:03 am
“Tallbloke is right. Do you prepare your breakfast with a hair dryer?”
No, but I do put water in the freezer and after a while I get ice cubes.
“By virtue of the second law of Thermodynamics, heat cannot be transferred from a colder to a warmer body”
A minor quibble with that statement. Heat cannot be transferred from a colder to a warmer body via conduction, but it can via radiation. IR from a colder body can be absorbed by a warmer body. I don’t think that invalidates anything else in the post though.
Perhaps we need to rename the “greenhouse effect” to something that is more descriptive? After all, that’s not how greenhouses work.
I want to thank Richard Garnache for his very illuminating post. Do you have a website, Richard?
After all these decades, how in this world can anyone talk about greenhouse anything and not be talking about water?
We’re still trying to come up with some plausible explanation of CO2.
A person would think, after all this time, and all the horrible things that are going to happen to us all, we might have some sort of clue.