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The 2nd law of thermodynamics and the greenhouse effect
Berényi - I would actually have to disagree about equilibrium states. If a constant input and sink of energy are maintained (sun and the 3 degree K of space), the climate will cycle around equilibrium based on the internal variance of weather. Currently we are moving towards (but have not reached) an equilibrium - but a 'steady-state' system will still reach an entropy balance (dynamic equilibrium) where energies do not change. As Riccardo stated, the MEP indicates the path taken towards equilibrium, or as I understand it entropic balance. That affects the speed of attaining equilibrium, not the final thermodynamic state. Re-reading Ozawa et al: they are indeed speaking of speed (delta) of entropy, not the final thermodynamic states. If you disagree, please point out the sections of the paper that indicate this. You have also not addressed my point here, that high entropy production if correct is already part of the climate sensitivity - it's already incorporated into our knowledge and models of climate behavior. -
Riduna at 11:08 AM on 26 October 2010Measuring CO2 levels from the volcano at Mauna Loa
Mauna Loa and other sampling sites provide an interesting record of increasing atmospheric CO2 but how much of it is the result of human activity (and how is that determined) and how much is from other sources? Global warming arises from the increased presence of greenhouse gases (CO2-e) in the atmosphere, CO2 being only of them. Do Mauna Loa and other stations measure the concentration of other greenhouse gases in the atmosphere? Measuring CO2 concentration only provides part of the picture. For example, as global temperatures rise melting permafrost and ice, methane is released from subsurface decaying material. When ocean water warms it is less able to absorb atmospheric CO2 and increases its release of that gas into the atmosphere. Are these effects identifiable and are they measured? When we talk of the importance of keeping the concentration of CO2 in the atmosphere to less than 450 ppm, should we not be stressing the importance of keeping the concentration of CO2-e in the atmosphere to less than 450 ppm?Moderator Response: Your questions are generally addressed in the following posts:
How do human CO2 emissions compare to natural CO2 emissions?
Water vapor is the most powerful greenhouse gas
What is methane's contribution to global warming? -
Berényi Péter at 10:33 AM on 26 October 2010The 2nd law of thermodynamics and the greenhouse effect
#59 KR at 07:53 AM on 26 October, 2010 If Riccardo is correct, this means that the MEP principle you brought up has zero effect on the equilibrium temperature change for various forcings, only (if the MEP hypothesis is true) upon the speed (time lags) at which the climate moves there Wait, I can see a conceptual confusion here. The climate system is never in thermodynamic equilibrium, not even close to one and the MEP tells nothing about the path to be taken there either. It's in a steady state, which is a completely different thing altogether. In this state a pretty stable stream of energy flows through it, arriving as low entropy sunlight and (part of it) leaving as high entropy thermal IR radiation against the cosmic microwave background. So there is also a constant rate of entropy production. In fact it is not really constant, just a target value actual entropy production tends to fluctuate around in a scale invariant manner. It is much like sandpile avalanche dynamics in this respect. If you change the system by increasing baseline IR opacity of the atmosphere a bit, I have already shown you it decreases entropy production rate (along with increasing average surface temperature) if all else is held unchanged. You can depict it as a landscape defined over a phase space of climate states by the entropy production rate function. MEP means the climate state tends to linger around a peak. As soon as baseline IR opacity is increased by a small quantity, the landscape gets rearranged somewhat. If there is a maximum entropy production principle at work indeed, for a neutral feedback you need the same climate state to be found right at a peak on the rearranged landscape, which is extremely unlikely. All other positions would involve some negative feedback and there is no room for a positive one at all. Of course the MEP is only a local constraint, meaning all sufficiently small changes of the climate state relative to the actual one tend to decrease entropy production rate. It does not mean there are no higher peaks at all along the landscape, accessible only through deep valleys (that is, not accessible under normal circumstances). With an ever increasing baseline opacity of the atmosphere at some point the topological structure of attractors over this landscape may get rearranged (at which point, we have no idea), so as a previously inaccessible peak becomes accessible along a continuous path with an ever increasing entropy production rate (or at least it only needs to jump through shallow valleys). If this happens, a climate regime shift occurs, but it is a highly nonlinear process, inexpressible in the climate sensitivity formalism. It is not clear either if this new steady state would imply higher or lower average surface temperatures (or the same ones with some regional rearrangement). Unfortunately mainstream climate science failed to ask these questions so far, so for the time being we do not have a chance to get proper answers. -
Riccardo at 09:07 AM on 26 October 2010The 2nd law of thermodynamics and the greenhouse effect
KR very much like the equilibrium state, i.e. that of maximum entropy, in statistical thermodynamics can be defined as the most probable state, the maximization of the entropy production rate may be thought as defining the most probable path toward equilibrium. I'm not an expert on non-equilibrium thermodynamics and I can't tell if the MEP path is always the fastest possible. In simple systems I guess it probably is, it's not obvious it will be so in general. -
Harald Korneliussen at 08:41 AM on 26 October 2010Irregular Climate podcast 13
Typo: Micheal => MichaelResponse: Fixed, thanks -
CBDunkerson at 08:14 AM on 26 October 2010Waste heat vs greenhouse warming
RSVP, back at 272 you wrote: "Imagine a lake whose level is seen to rise 3 inches in the course of 150 years due to a new spring breaking ground up stream." I couldn't "imagine" this because even the analogy breaks the laws of physics. So let's see if fixing it helps you see what we are saying. If a lake (i.e. the Earth's atmosphere) suddenly acquired a new source of incoming water (i.e. heat), such as the spring in your example (i.e. waste heat), it would NOT slowly increase in depth (i.e. temperature) over 150 years. The depth would increase almost immediately and then stop because the higher water level would allow more water to flow OUT of the lake as well. Once the new net outflow was equal to the new net inflow the new water level of the lake would then be set. How long the spring continues pouring in water is irrelevant... it doesn't lead to an ever increasing water level because when the inflow increases the outflow inherently must as well. Further, if the new inflow ever stopped or declined (i.e. we began producing less waste heat) the lake would quickly drop down to a lower level... the constant inflow is required just to MAINTAIN a small increase in the water level rather than producing a continually increasing level. Now, if you were to put sand bags blocking some of the streams leading out from the lake (i.e. decrease radiation outflow by increasing greenhouse gases) the lake would rise until the net outflow from the remaining streams, or possibly over the tops of the sandbags, again equaled the net inflow. The water level would then stay at that new height until the sandbags were removed. The inflow and outflow of water in a lake and energy in the atmosphere are pretty close corollaries... so long as you stick to actual physics for both. -
scaddenp at 07:54 AM on 26 October 2010Blaming global warming on the oceans - a basic rebuttal
Dan, since oceans cant generate heat, then heat from oceans cant be forcing only a mechanism. So the correct approach is do what you do, but plug in the real forcings instead. Already done of course, looks within Benestad & Schmidt -
The 2nd law of thermodynamics and the greenhouse effect
* state * -
The 2nd law of thermodynamics and the greenhouse effect
Riccardo - So, the MEP principle doesn't affect the thermodynamic end stateto, but simply says that systems will tend to move to that state as quickly as possible? Berényi - If Riccardo is correct, this means that the MEP principle you brought up has zero effect on the equilibrium temperature change for various forcings, only (if the MEP hypothesis is true) upon the speed (time lags) at which the climate moves there. -
Riccardo at 07:27 AM on 26 October 2010The 2nd law of thermodynamics and the greenhouse effect
nealjking and indeed you can't. First, the MEP principle says other things than the 2nd law; it says that a system out of equilibrium will follow the path that maximises the entropy production rate. Note that it does not define the final equilibrium state, which (apart from metastable states which might occur) is still given by standard thermodynamics; it just tell us the path toward it. Second, it aspires to be a principle and hence it's not demonstrated; only time will tell if it really is a general principle or if it has a limited range of validity. It is a very interesting topic, whose consequences are yet to be unveiled. Unfortunately, it currently does not add much to our knowledge of the final fate of our planet, so neatly given by standard thermodynamics. -
RSVP at 07:06 AM on 26 October 2010Waste heat vs greenhouse warming
Bibliovermis #335 "... a well-established field of scientific endeavor is composed of grossly incompetent, corrupt individuals" This is a good point, and we would all be better off assuming good will on all sides. -
Daniel Bailey at 07:05 AM on 26 October 2010Why is Greenland's ice loss accelerating?
Stop the presses, this just in:Danish research scientist Sebastian Mernild of Los Alamos National Laboratory in the US told national daily newspaper Jyllands-Posten that his calculations show that 540 cubic kilometres of inland ice, weighing approx. 500 gigatons, have melted this summer, which is 25-50% more than in a typical year.
According to Jyllands-Posten, climate researcher Jason E. Box from Byrd Polar Research Center at Ohio State University, USA, is also saying that the inland ice melting has been particular strong this year:"It is my assessment that we have had the strongest melting since they started measuring the temperature in Greenland in 1873."
Let the good times roll. The Yooper -
Waste heat vs greenhouse warming
RSVP - If you disagree with the level of CO2 forcings, I would suggest taking it to the How do we know more CO2 is causing warming thread; that's where it's appropriate. The value of 2.9 W/m^2 is quite well established from physical theory, from multiple orbital and ground measurements, etc. -
GFW at 06:48 AM on 26 October 2010Measuring CO2 levels from the volcano at Mauna Loa
For those wondering about how the offshore breeze results in higher air descending to the mountaintop, it's just fluid continuity. If air at or below the mountaintop is flowing outward, something has to replace it ... which means air from higher up. While air is not a "perfect fluid", divergence still has to be pretty darn close to zero :-) -
Waste heat vs greenhouse warming
RSVP > if the atmosphere were to always radiate more and more in a way that exactly compensated any positive changes in heat, global warming wouldnt be possible Seriously, I am perfectly aware that "Radiated energy increases as the 4th power of temperature" These two sentences are in direct contradiction to one another, and reflects your inability to accurately visualize the simple logic of how this would play out. If there is a positive change in the rate of heat input, then temperature will increase. If temperature increases, then radiated energy increases. As long as the output radiation is less than the input energy, then temperature will continue to increase, and just as you claim to be aware of, so will radiated energy. If temperature continues to increase, then output radiation will continue to increase, and if it does, it is mathematically and logically inevitable that eventually output will increase to a point where it matches input, at which point temperature increases will stop. If temperature increases stop, then so will changes in output, and since this is precisely the point where input matches output, there will be no more changes to the total energy content of the system. The overall temperature has gone up, but past this point there is no more accumulation. -
nealjking at 06:41 AM on 26 October 2010The 2nd law of thermodynamics and the greenhouse effect
#54, Berényi; #55, Riccardo: Looking briefly at Ozawa, I notice again and again the phrases: "the hypothesis of MEP," "that might be applicable." Why would I want to construct an understanding of the 2nd law on the basis of something that looks rather speculative? -
The 2nd law of thermodynamics and the greenhouse effect
Berényi - Thunderstorms and hurricanes are excellent examples of increasing local entropy, not decreasing it as you claim, they reduce order. A small turbulent variation in updrafts can trigger a thunderstorm, tipping a temporarily ordered system downslope. Pre-storm states are more ordered, with warm wet air present - a thunderstorm lifts and condenses approximately 5×10^8 kg of water vapor. Hurricanes do much more. The result is higher entropy, more disorder, less concentration of energy. What you have argued is that large scale fractal patterns of water vapor, or cloud formations of some kind, would form as part of local variation within the degrees of freedom of the climate system. Large scale patterns of water vapor (big enough to change the climate, certainly) would require long term persistent order to exist. That's a widespread, persistent low entropy system, and you have presented no evidence for such to exist. Your example of thunderstorms and hurricanes does not support your theory; quite the contrary. More to the point: Ozawa et al 2003, as Riccardo points out, indicates that "turbulent fluid systems adjust themselves to the states of maximum entropy production". Assuming that this is so (and it seems a reasonable hypothesis), the climate system is already adjusted to the state of maximum entropy production. Your hypothesis that the climate will adjust to increase entropy and avoid warming fails to consider this - that it's already adjusted in that fashion, and that this max entropy production is part of the existing climate and climate feedbacks. Maximum entropy production won't suddenly switch on in response to climate forcings - it's already there, already part of the system, already part of the climate sensitivity. It certainly won't kick in abruptly to save us from greenhouse gas heating. -
RSVP at 06:29 AM on 26 October 2010Waste heat vs greenhouse warming
KR #333 "Anthropogenic heat flux = 15 TW/year" You mean 15 TW all year. Day and night. As there are 60 x 60 x 24 x 365.25 = 31536000 seconds in a year, that gives you 31536000 x 15 x 10E12 = 473040000 x 10E12 or 473 x 10E18 Joules. The heat flux value you cite for CO2 is an estimate, not a measurement; derived by correlating the observed warming with the observed CO2 increase and contrasting this with the known total solar heat flux. But the situation would be completely inverted, IF you started with the opposite assumption. So the only way you could be right about this is if you can prove that all that energy being injected into the environment is having no impact, (instead of warming things, it hightails for the stars). This is hard to believe as glaciers and polar caps melt before us. -
Riccardo at 06:17 AM on 26 October 2010The 2nd law of thermodynamics and the greenhouse effect
nealjking "I am not an expert on non-equilibrium thermodynamics." you're in good company, I don't think you'll find many experts on non-equilibrium thermodynamics around, let alone on the MEP principle. As with the 2nd law of thermodynamics (just a reminder, it's the topic of this post) you'll find, instead, a lot of misuses. Apart from Miskolczki "theory", there's really no contraddiction between an increased GHG effect and the MEP principle. A carefull look at section 3 in Ozawa et al. 2003, and fig. 5 in particular, should make it clear. -
Berényi Péter at 06:05 AM on 26 October 2010The 2nd law of thermodynamics and the greenhouse effect
#52 KR at 02:56 AM on 26 October, 2010 Local effects (more ordered cloud formations, less uniform water vapor distributions, etc., that you have suggested in the past) that are not locally high entropy will not occur What you are effectively saying is hurricanes, supercells or tornadoes (with their more ordered cloud formations, less uniform water vapor distributions, etc.) are impossible. I don't think you mean it.
Although the moderator was kind enough to delete it once, I give it another try. MEP is nothing fancy, really. The underlying principle is the same as for water flowing downhill; it simply follows the steepest gradient available. Note it says a bit more than the 2nd law, which only states water would not flow spontaneously uphill.
In systems like this local entropy fails to win out, somehow. Think about it.
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robert way at 06:00 AM on 26 October 2010Do critics of the hockey stick realise what they're arguing for?
Protestant, "We already have evidence on 60 year cycles like PDO and AMO after all, which are caused by winds, which are caused by pressure changes in condensation (cloud formation, models ignore this)" The AMO is not caused by this process at all. You should consider reading the literature prior to making grand statements that are vitally flawed. The AMO is a proxy for the strength of the thermohaline circulation (THC). Positive phases indicate a strengthening of the THC and negative phases indicate a weakening of the THC. It occurs over a roughly 70 to 80 year period and is directly linked to sea ice transport through the fram strait. I can give you a more direct explanation if you prefer? Another side note, Judith Curry may be well-known but I would rather get my information from other people than her. There's a reason she's taken such a beating at RC and elsewhere, it is because she is often wrong. Finally, I do agree with one thing you had to say, this post does insinuate that there is a clear forcing and effect. I believe that millennial scale climatic changes are inherent within the climatic system as found by Viau et al (2006) however I don't think they have a cloud origin. I would guess ocean driven with some sort of Solar initiation perhaps. -
nealjking at 04:00 AM on 26 October 2010The 2nd law of thermodynamics and the greenhouse effect
Berényi: I am not an expert on non-equilibrium thermodynamics. My main exposure to this MEP claim has been through Miskolczki's claim that the MEP ruled out any possibility of the enhanced greenhouse effect at all. I spent some time trying to find out what this meant, but it eventually became clear enough to me that Miskolczki was also not an expert in non-equilibrium thermodynamics, and was using this principle, that he did not fully understand, to counter well-known physics that everybody understands. This seems to me not to be the most prudent way to arrive at an understanding of phenomena. Usually, one is better advised to try to extend one's understanding from things well known to things less known. -
Andy Skuce at 03:17 AM on 26 October 2010Measuring CO2 levels from the volcano at Mauna Loa
Thanks for the comments. I replaced "offshore breezes" with different wording that I hope will be unambiguous. I also reworded the latter part of that sentence to make it more clear that at night the observatory samples well-mixed high altitude air from the Central Pacific rather than the lower altitude air that has come upslope from the lower reaches of the island and which may be slightly depleted in CO2 due to the effects of the vegetation there. Some of this will be discussed in more detail in a forthcoming Advanced Version of this rebuttal. -
Bibliovermis at 03:01 AM on 26 October 2010Waste heat vs greenhouse warming
Why should we be happy about explaining, and re-explaining & then explaining yet again, basic, fundamental physical properties to somebody who adamantly insists that these misconceptions are the reason why a well-established field of scientific endeavor is composed of grossly incompetent, corrupt individuals? Yes, the scientific theory of anthropogenic warming can be disproven. Your lack of understanding and refusal to learn is not sufficient. We have been magnimous, but you are wrong - plain and simple. Your conceptions of how heat moves through the atmosphere are indeed utter nonsense. Indignation & insults (e.g. "you're just insecure") do not impart validity. Repeating the same misconception over & over & over is a good way to get people to snap at you. Global warming is how more & more energy is radiated from the planet. No additional energy can leave the system until there is an increase in temperature. The temperature cannot rise without more energy leaving the system. Energy can only leave the system through radiation; convection only moves it around internally. Energy cannot simultaneously cause a temperature increase & remain in the system (i.e. accumulate). -
The 2nd law of thermodynamics and the greenhouse effect
Berényi - Are you arguing that the climate will (by virtue of many degrees of freedom) increase entropy production in some fashion in order to avoid raising temperatures? Do you have any evidence for such an assertion? Note that if a system could reach a more entropic state by reordering internal components/relationships, but those internal elements would require a less entropic (more ordered) state, local entropy will win out and the system entropy will be the product of the local (internal) entropies. Local effects (more ordered cloud formations, less uniform water vapor distributions, etc., that you have suggested in the past) that are not locally high entropy will not occur. In short, the system is the product of the components, not the other way around. And quite frankly a warmer planet with a higher effective photosphere for portions of the emission spectra is the most entropic solution - at least, according to and supported by the data. -
Albatross at 02:43 AM on 26 October 2010DMI and GISS Arctic Temperatures: Hide the Increase?
Peter @129 and 133, Thanks for this Peter-- I realise that it is easy for me and others to talk hypotheticals, but another story entirely to actually track down the data, undertake the analysis and then write it up. Great work. Peter "My summary based on the best available evidence is that Summer Arctic temperatures are increasing slightly, the Lansner chart contains errors and any conclusions based on this chart are likely to be incorrect. Based on your findings and those of Screen and Simmonds (2010) I concur with that assessment. "I have concluded that "pixel counting" is not an appropriate method for analysing trends or data in this case. The Lansner chart has large differences from the correct DMI values and it appears the conversion of numerical data to images and then pixel counting from these images is easily capable of creating bad data." FWIW, I would concur with that assessment as well. It seems that the alleged "cooling" is an artifact of a combination of issues with the DMI data and Lansner's methodology and/or analysis. I would also like to second what Doug wrote @133. It may be worth bringing this to the attention of DMI as well...the poor match that you show between ERA-interim and DMI (for the melt season) is rather troubling. Just one example in addition to the "step" issues, something odd seems to have happened with the DMI data between 1991 and 1995. -
CBDunkerson at 02:43 AM on 26 October 2010Waste heat vs greenhouse warming
muoncounter #331: "In order for your argument at 317 to work at all, you must accept the points (its warming, its not the sun, etc) made in 325." I dunno. I've yet to meet a dedicated 'skeptic' who isn't capable of passionately believing three or more contradictory things at the same time. -
Daniel Bailey at 02:22 AM on 26 October 2010Measuring CO2 levels from the volcano at Mauna Loa
Re: chrisd3 (8) As a former nautical cartographer, I didn't realize that it wasn't common knowledge about such breezes. You and Kevin McKinney should share sailing backgrounds sometime. -
michael sweet at 02:07 AM on 26 October 2010Blaming global warming on the oceans - a basic rebuttal
Dan, The issue that I have with your argument is that sea surface temperature is determined by the interaction of the atmosphere and the ocean. Your proposal suggests that global warming is caused by the ocean heating the atmospehre. What heats the ocean? Since both the ocean and the atmosphere are warming the heat has to come from somewhere. CO2 heats the atmosphere. The heated atmosphere heats the ocean. The energy to heat both comes from the sun. Your equation works because the ocean is heated by the atmosphere. Since the two are linked you observe this link with your calculation. -
Waste heat vs greenhouse warming
RSVP - No, not insecure, just tired of the same disproven skeptic arguments being brought up again and again.. oh look, and again. Increased thermal radiation affects the contributions of anthropogenic heat flux, and it affects the contributions of greenhouse gases. The same rules apply in all cases. Energy changes lead to temperature changes, and thence to radiation changes that tend to balance out the energy change. The 4th power of temperature relationship with energy is the negative feedback that limits temperature changes. However, GHG's are two orders of magnitude larger, and hence have a much larger effect. I'm quite frankly puzzled as to why you continue to think that AHF dominates global warming. Anthropogenic heat flux = 15 TW/year Greenhouse Gas entrapment = ~1550 TW/year Now, which of these will dominate climate effects? -
RSVP at 01:48 AM on 26 October 2010Waste heat vs greenhouse warming
KR #330 When you snap "incorrect" and "utter nonsense", it makes you appear insecure. If I am the one thats all messed up, you could be a little more magnanamous. I may be completely wrong, and if so, at least in being wrong, it would be just that much more proof that AGW is a good theory. You should be happy to proove me wrong, not upset. Besides, I am not sure what you have to worry about? There is still 20,000 experts out there that have signed on who would have to be convinced. AGW is an entrenched theory with a lot of backers. One might ask if it is even possible to disprove at this point, assuming it were completely flawed. Seriously, I am perfectly aware that "Radiated energy increases as the 4th power of temperature". What I find strange is how increased thermal radiation is used to undermine the contribution of waste heat, while the basis of GHG heating depends on jsut the opposite. Conclusion. Calm down, be happy. Besides, as far as every reading this, you are winning, (and won before the discussion even began given the rule set). -
Riccardo at 01:46 AM on 26 October 2010Measuring CO2 levels from the volcano at Mauna Loa
chrisd3, the Mauna Loa Observatory is already high enough to be a good place to measure background CO2 concentration, unless air coming from lower elevations "contaminate" the readings. At night, or whenever there's no upslope wind, there's no reason for concern. Whether the air comes from higher up (which is often true) or from the same level is irrelevant. -
nealjking at 01:39 AM on 26 October 2010The 2nd law of thermodynamics and the greenhouse effect
#48, Berényi Péter; #49, Kooiti Masuda: TonyWildish is not talking about the emissivity of the gas, but the "effective emissivity" of the Earth. So the whole discussion about Kirchoff's law, etc., has nothing to do with what he's talking about. He's just saying that the Earth will "have a harder time" tossing off radiation at a specific frequency if the absorption coefficient of the atmosphere at that frequency increases. "Emittance is proportional to the product of emissivity (a dimensionless number) and the fourth power of absolute temperature." This is not quite true: the T^4 law relates to the total power integrated over all frequencies, in a case when there is no frequency-specific filtering (like absorption lines): this doesn't apply to cool gases, which have line spectra. In these situations, what is more relevant is the Planck distribution, which is multiplied with the absorption spectrum to get the emission spectrum. Maximum entropy production: I am not very familiar with this "principle," and have no clear reason to believe in it. The only other time I've heard of anyone trying to apply it to atmospheric processes was when Miskolczi was trying to disprove the possibility of the greenhouse effect. I didn't believe it then, and I have no reason to believe it now. -
muoncounter at 01:27 AM on 26 October 2010Waste heat vs greenhouse warming
#326: "Not sure why you say this?" In order for your argument at 317 to work at all, you must accept the points (its warming, its not the sun, etc) made in 325. Like it or not, you're an AGW guy now. "There is no waste heat sunset." Nor is there a waste heat correlation. Your calculation says all energy consumed directly warms the atmosphere; temperature anomalies should correspond with historic energy consumption (see EIA energy consumption tables). You picked one year's energy consumption; over the longer term, how well do temperature anomalies track energy use? Your model makes a testable prediction. In order for your model to be taken seriously (although most others here have already said it should not), it still must be checked against observations. Sunrise, sunset. -
Berényi Péter at 01:20 AM on 26 October 2010The 2nd law of thermodynamics and the greenhouse effect
#49 Kooiti Masuda at 22:42 PM on 25 October, 2010 For entropy production in the climate system, see Ozawa (2003) (Unfortunately I do not find a free copy) Dear prof Masuda, here is a copy of the paper you are referring to. Reviews of Geophysics, 41, 4 / 1018 2003 doi:10.1029/2002RG000113 THE SECOND LAW OF THERMODYNAMICS AND THE GLOBAL CLIMATE SYSTEM: A REVIEW OF THE MAXIMUM ENTROPY PRODUCTION PRINCIPLE Hisashi Ozawa, Atsumu Ohmura, Ralph D. Lorenz & Toni Pujol Unfortunately their claim "On the contrary, absorption of radiation is essentially a linear process; its rate is given by the flux of radiation multiplied by the absorptivity of the material under consideration. There can be no feedback mechanism for the strength of the flux or the absorptivity in this process. Radiation can therefore be seen to be just an energy source for the climate system." is not a valid one, as absorption of radiation clearly depends on things like clouds, snow cover, foliage and airborne dust. Looks like there can be feedback mechanisms after all, as distribution of many absorbers are determined by climate. Their omission of the factor 4/3 from the standard expression of radiation entropy is strange. Also, total entropy production is the difference between entropy of outgoing (reflected/dispersed short wave and emitted thermal) radiation and that of incoming sunlight. The MEP, being a pretty universal principle covering all steady state open thermodynamic systems with sufficient degrees of freedom, should not differentiate between internal modes of energy transfer in a way they claim. -
chrisd3 at 01:19 AM on 26 October 2010Measuring CO2 levels from the volcano at Mauna Loa
Daniel #7:onshore breezes are those winds that normally flow toward the land from the sea
Quite right. As a former sailor, I'm quite ashamed that I didn't even notice that, and even repeated it. The sentence should say "onshore" rather than "offshore." But still I don't think it's the onshore/offshore direction that brings air down from the upper atmosphere. -
Stu at 01:17 AM on 26 October 2010Mauna Loa is a volcano
Good stuff Dan, and good article Andy. The comments at American Thinker are just... argh! So boneheaded! Still, I wont judge all Americans by that - just the ones who let American Thinker do their thinking for them ;-) -
Waste heat vs greenhouse warming
RSVP - "If the atmosphere were to always radiate more and more in a way that exactly compensated any positive changes in heat, global warming wouldnt be possible" Incorrect. The Earth doesn't radiate more unless it warms, thus positive energy changes cause global warming. Cause >> effect: Positive energy changes >> global warming >> increased radiation >> steady state Claiming that this relationship disproves global warming is utter nonsense. -
Waste heat vs greenhouse warming
RSVP - "I understand the theory as modeled by a solid blackbody the size of the Earth": Not quite what I said, and that's worth clarifying. The Earth is a 'graybody', not a blackbody, with notches in the emission spectra from among other influences greenhouse gases. Radiated energy increases as the 4th power of temperature, scaled by the emission spectra of the body in question. Graybodies never emit as efficiently as theoretic blackbodies, but they certainly do emit. Starting from a rough equilibrium, with the Earth radiating the energy it absorbs from the sun (known value) at current temps, an average increase of 0.015°C to 0.034°C emits an additional 15 TW/year (plus climate sensitivity scaled feedbacks) to space, thus reaching a new state of equilibrium between energy in/energy out. And once equilibrium is reached the system ceases to change due to that forcing. The "λ" in the sensitivity equation is exactly that - sensitivity to energy perturbations. This ranges from a low pushed by some sceptics (Lindzen and Choi, for example), to fairly high values given by loosely bounded upper limits. See Figure 4 of "How sensitive is our climate" to see a good discussion of this range. So no, "I get the sense as applied to the effects of GHGs that its value reflects the assumption that GHG are the main cause of the observed global warming and in this sense the operation is basically both subjective and circular" is incorrect. This is sensitivity to any forcing that adds energy to the climate system, which is why it applies to TSI variations, aerosols, GHG's, ice albedo, etc. Oh, and to anthropogenic heat flux... -
Daniel Bailey at 00:34 AM on 26 October 2010Measuring CO2 levels from the volcano at Mauna Loa
Re: Offshore/onshore breezes The accepted understanding is that onshore breezes are those winds that normally flow toward the land from the sea during daylight hours, as the land will typically be much warmer during the day. At night, the land loses its heat through radiative processes, and the winds change to downslope: the sinking cooler air moves toward the sea, moving offshore from the land to the sea. The Yooper -
RSVP at 00:33 AM on 26 October 2010Waste heat vs greenhouse warming
Bibliovermis #327 If the atmosphere were to always radiate more and more in a way that exactly compensated any positive changes in heat, global warming wouldnt be possible, no matter what the source. Waste heat is warming the air and in general convectively. This does not make the best launchpad for radiation. -
Riccardo at 00:07 AM on 26 October 2010Measuring CO2 levels from the volcano at Mauna Loa
chrisd3 "at night, the prevailing winds are offshore breezes" i guess he means going offshore, although you're right that usually it is intended the other way around. Yvan Dutil the Mauna Loa Observatory is at 11,135 ft which should be something like 3300 m (will the descendants of the anglo-saxons ever convert to the SI units? :)). It should be high enough. -
Yvan Dutil at 23:46 PM on 25 October 2010Measuring CO2 levels from the volcano at Mauna Loa
Well, in Mauna Kea and Mauna Lea, plant stop at 3000 m. This the normal height of the boundary layer. At night, this layer is normally much thiner due to reduction of convection. Astronomer make use of this and put telescope on the top of Mauna Kea for that reason. Actually, on top of Mauna Kea, the air flow is coming strait from the pacific ocean. This is why it is so stable, which provide a good seeing. Similar situation occur in Mauna Loa but since the altitude is lower, the effect is less obvious. -
muoncounter at 23:34 PM on 25 October 2010Extreme weather isn't caused by global warming
#9: "first report doesn't make sense" I don't expect headlines in newspapers to make sense. As you say, the headlines and blogposts that 'The Ice Age Cometh' will indeed be all over the place. Whatever happened to the old idea that Arctic melting flooded the North Atlantic with cold, fresh water, thereby shutting off the northwards-flowing Gulf Stream? Has that mechanism fallen out of favor these days? -
The Skeptical Chymist at 23:34 PM on 25 October 2010Throwing Stones at the Greenhouse Effect
Speaking of the strength of the greenhouse effect and what would happen if you took out all the C02, the good folks at NASA have just published a paper in Science looking at precisely this question. The Science paper is here but for those who can't access it there are good discussions on the NASA GISS website (including most of the figures from the Science paper) here and here. The answer seems to be that while C02 (and other GHGs like methane) make up around 25% of the greenhouse effect, without them water vapor crashes out of the atmosphere, leaving a planet with an average temperature of -21dC. It might not be a completely snowball earth though, the equator may get enough heat to keep the oceans at a balmy 1dC. Interesting stuff, but the take home message is spelled out in the title of the paper: "Atmospheric CO2: Principal Control Knob Governing Earth’s Temperature" -
Kooiti Masuda at 22:42 PM on 25 October 2010The 2nd law of thermodynamics and the greenhouse effect
I agree to the 2nd to 5th paragraphs of #48 by Berényi Péter (#48), but I disagree to the last two paragraphs. Excuse me, I cannot fully write my reasoning right now. For entropy production in the climate system, see Ozawa (2003) (Unfortunately I do not find a free copy). The authors suggest that the principle of maximum entropy production seems to be applicable to fluid motion processes, but not to the whole climate system including radiative processes. -
chrisd3 at 22:18 PM on 25 October 2010Measuring CO2 levels from the volcano at Mauna Loa
the prevailing winds are offshore breezes, which bring clean air from high in the atmosphere down to the observatory Is that accurate? Offshore breezes bring in air from the direction of the ocean, but not necessarily from "high in the atmosphere." I think you're mixing up the onshore/offshore pattern with a slightly different diurnal pattern. During the day, the wind at Mauna Loa tends to be upslope (upward from the island), while at night the wind tends to be downslope (downward from the atmosphere). Changes in temperatures drive both patterns, but it's the downslope effect, not the offshore effect, that brings down air from higher in the atmosphere. That's been my understanding, anyway. -
Berényi Péter at 21:36 PM on 25 October 2010The 2nd law of thermodynamics and the greenhouse effect
#41 TonyWildish at 02:07 AM on 25 October, 2010 you can think of it as effectively lowering the emissivity of the earth at certain frequencies, by lowering the transparency of the atmosphere to those frequencies No, you can't. In fact by lowering atmospheric transparency, you increase emissivity. That's Korchoff's law of thermal radiation. If the atmosphere would be in thermodynamic equilibrium, that is, if it were isothermal, lowering its transparency would increase not only emissivity, but also its emittance, so adding a small amount of GHG to a perfectly transparent atmosphere (let's say made of Nitrogen and Argon) would decrease its temperature (something like that is happening to Earth's stratosphere). However, the atmosphere is not in equilibrium, just in a more or less steady state with a continuous flow of energy going through it, associated with a steady rate of entropy production. If there's already some GHG content in such an atmosphere, the upper layers tend to cool faster (because they are more "visible" from space), which is why they are kept at a lower temperature. If you increase GHG content (as we have seen, also increasing emissivity by the very same act), the "photosphere" (the layer from which IR photons have a chance to escape to space unimpeded) goes higher, that is, to a colder place. Emittance is proportional to the product of emissivity (a dimensionless number) and the fourth power of absolute temperature. In some cases the latter one decreases more than the increase in the first term, so their product also decreases. But by decreasing the emittance, entropy production rate also decreases (while internal entropy contents of the system increases). Now, open systems with many degrees of freedom tend to assume a state of maximum entropy production (with minimum entropy contents, that is, a tendency to maintain internal order). So to prove increasing GHG contents of the atmosphere decreases overall IR emittance indeed, it is not enough to show photosphere rises to a higher layer in a narrow IR band, you also have to demonstrate the climate system has no way to reconfigure itself (even with its gazillion degrees of freedom) to a state which restores entropy production rate to its former value or at least makes it decrease less than indicated by first order GHG calculations. If you fail to do so, a negative feedback is likely (which makes AGW scare moot). -
JMurphy at 21:34 PM on 25 October 2010Extreme weather isn't caused by global warming
That first report doesn't make sense, muoncounter. Firstly, we have no direct evidence of temperatures going back that far, so how can it be judged the coldest in 1000 years ? Secondly, isn't the Little Ice Age meant to be the coldest period over the last 1000 years (according to proxies), i.e. 3-400 years ago ? Thirdly, wasn't there a Medieval Warm Period at various times and places, about 1000 years ago - again, according to proxies ? Overall, I bet the so-called skeptics are drooling at the possibility of this coming to pass, despite the fact that they will have to rely on the veracities of the instrumental temperature records and the proxy records, and ignore the LIA and MWP - just so they can scream : 'Ice-age is coming !' Perhaps this will be another good example of their incoherence. -
Nick Palmer at 20:23 PM on 25 October 2010Do critics of the hockey stick realise what they're arguing for?
Shoot this down if you want, but I think the sceptics obsession with the MWP proves that they are Lovelock/Hansen style "alarmists" (or would be if they thought about it...). The most "sceptical" of those credible scientists, quoted by the denialist element (Lindzen et al), reckon that their purported low climate sensitivity will lead to less than 1 degree C for a doubling of CO2, which would take us (globally)in due course outside the peak of the (probably) local MWP. Surely the most fervent deniers must accept that, if it was as fertile and lush and lacking in ice as they claim, then also surely the albedo of "fields of corn" Greenland and elsewhere, such as Northern Russia and Alaska etc would have been a lot lower. If they accept that a small amount of increase from the previous cooler era lead to a fertile darker surfaced Greenland etc then they must accept that ice sheets are very much more prone to radical melting and disappearance due to small temperature changes than hitherto suspected in which case they must realise that their beliefs must mean there is a very large positive feedback that melts ice quickly although they would also have to explain why the rise in the MWP was not much larger if the planetary albedo was so much less too. So, if they believe in the denialist/Singer version of the MWP, they must expect Greenland to melt rapidly leading to a greater albedo feedback that mainstream climate science does not expect for a long time. Deniers are alarmists!
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