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Protector at 11:12 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
Tom Curtis @ 590: Yes, this is exactly what I meant as you articulated it in the first paragraph of #590. Also, your reply to RW1 is right on! -
Riduna at 11:11 AM on 17 March 2011Maize harvest to shrink under Global Warming
So, what does this article tell us that we did not already know? To those who are concerned with the broader topic of food security in a warming world with a population expected to exceed 9 billion within 40 years – not much. To those who wonder what impact SLR and salt water flooding of river delta’s and low-lying fertile coastal plains will have on food production – even less. To those worried about the already failing adequacy of freshwater for agriculture in the face of diminishing mountain snow and glaciers – nothing useful. Academic research, publication of papers and debate thereon is undeniably important and is to be encouraged. However sometimes those efforts do seem rather specialised and esoteric in a world facing some very serious, relatively short-term problems, arising from the broader effects of AGW on food production. A dissertation on the effects on maize yield grown where temperature exceeds 30C by 1degree-day is important but does it deal with future real world conditions where average global temperature may rise by 2C by mid-century? -
RW1 at 11:07 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
Tom Curtis (RE: 587), "2) At the Surface: Absorbed Solar Radiation + Absorbed Back Radiation ~= Thermals + Evapo/transpiration + Surface Radiation <=> 161 + (10.6 + 48.8 + 50.1 + 222.6) ~= 17 + 80 + 396 <=> 493.1 ~= 493" There is 239 W/m^2 of post albedo coming in, 239 leaving at the top of the atmosphere, and 396 W/m^2 at the surface. Your energy flow calculations do not adhere to this; thus, Conservation of Energy is not being met. You don't seem to understand this, so I'll break it down into a series of separate questions and we'll go from there: 1. Do you agree that 239 W/m^2 of post albedo enters the system and ultimately becomes 396 W/m^2 at the surface? 2. Do you agree that the atmosphere cannot create any energy of its own? 3. Do you agree that 239 W/m^2 is leaving the system at the top of the atmosphere and all of this is radiative? 4. Do you agree that all of the 396 W/m^2 emitted by the surface is radiative? 5. Do you agree that the 396 W/m^2 emitted by the surface is a result of its temperature and nothing else? 6. Do you agree that latent heat and thermals are kinetic energy (non radiative) moved into the atmosphere from the surface? 4. Do you agree that because latent heat and thermals are kinetic, their energy moved into the atmosphere is in addition to or independent of surface emitted radiation? -
RickG at 11:02 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
Ryan @ 589
Specifically, what is it that you guys don't understand about this diagram? You are trying to make it into something that it is not.
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Berényi Péter at 10:46 AM on 17 March 2011What would a CO2-free atmosphere look like?
OK, 195 K is -78°C. Still, it is much lower than global effective temperature in the 18-22.5 THz range. -
Tom Curtis at 10:40 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
Protector @582, I could have stated (3) better, but it should do for current discussion. More accurately, the GHG concentration determines the altitude of the effective radiation. The need to balance incoming solar radiation with outgoing longwave radiation then determines the temperature at that altitude, which then governs the temperature at the surface by means of the lapse rate. DB, thanks, but I do not have entire confidence in myself. I try though. RW1 @586, until you can identify a physical mechanism whereby CO2 or H2O molecules in the atmosphere can determine the original source of the energy they are emitting, your claim is clearly wrong. Bear in mind that the emitting molecule may not have been the molecule that originally absorbed the energy, but may have gained it after a series of collisional transfers in the atmosphere.Moderator Response: Your first paragraph of this comment helped me a lot. -
JMurphy at 10:39 AM on 17 March 2011Republicans to Repeal Laws of Physics
Gilles, the 'debate' is between Creationism and Evolution, so that should convince you that not everything is settled - as it seems to have done with regard to AGW. Details are unimportant : the debate is all, apparently. As for global warming, please read these threads : The Big Picture Newcomers Start Here They should give you many assertions concerning global warming.Moderator Response: [DB] I appreciate your talents and determination, but hopefully by now you realize what you're dealing with. -
L.J. Ryan at 10:38 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
RickG @ 580 "And again, the diagram is about the distribution of energy, not temperature. " Rick in what form can one quantify the "loose" atmospheric energy? As you say, it is not temperature, so how do you know is there...can it be measured? Measured of course, not based on temperature. And by what means is the atmospheric energy stored? -
Berényi Péter at 10:37 AM on 17 March 2011What would a CO2-free atmosphere look like?
#69 Tom Curtis at 05:39 AM on 17 March, 2011 The result was to increase OLR by 27 watts Impossible. You did something terribly wrong. The flux emitted by a black body between 18 THz and 22.5 THz (wavenumber 600 cm-1 & 750 cm-1) at 255 K is 39 W/m2. If current abundance of CO2 would decrease it by 27 W/m2, effective temperature of the photospehere in this frequency range would be 195 K (-102°C), which is way below any temperature ever observed in terrestrial atmosphere. -
Protector at 10:35 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
RW1 @ 586: I think it was Tom Curtis, who made a comment earlier that it's difficult and probably physically not sound to try separating IR fluxes like that, because we are dealing here with absorption/re-emission NOT reflection of radiation. From what I've read elsewhere, these two processes are physically quite different ... But maybe the other experts would not agree. -
deyanaus at 10:34 AM on 17 March 2011Maize harvest to shrink under Global Warming
I'm a bit disheartened by the overall quality of comments, but hey just in case anyone is genuinely interested, here is a link to a similar study done recently for wheat in the conditions of NW Turkey. -
Tom Curtis at 10:32 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
RW1 @583: 1) At the TOA: Incoming Solar Radiation ~= Outgoing Longwave Radiation + Reflected Solar Radiation <=> 341 ~= (40 + (6.4 + 29.2 + 29.9 + 133.4)) + 102 <=> 341 ~= 340.9 Check! 2) At the Surface: Absorbed Solar Radiation + Absorbed Back Radiation ~= Thermals + Evapo/transpiration + Surface Radiation <=> 161 + (10.6 + 48.8 + 50.1 + 222.6) ~= 17 + 80 + 396 <=> 493.1 ~= 493 Check! 3) For the atmosphere: Solar Absorbed by Atmosphere + Thermals + Evapo/transpiration + (Surface Radiation - Atmospheric Window) ~= Back Radiation + OLR emitted by atmosphere including clouds ~= 78 + 17 + 80 + (396 - 40) = (10.6 + 48.8 + 50.1 + 222.6) + (6.4 + 29.2 + 29.9 + 133.4) <=> 531 ~= 531 Check! All units in w/m^2. Slight errors introduced by rounding, and a slight inequality exists because the Earth is accumulating energy. Other than that, it all adds up if you make sure to use the correct figures. -
deyanaus at 10:26 AM on 17 March 2011One of the best climate change ads I've seen
The author is apparently Ferdi Rizkiyanto, an Indonesian (according to this site). His blog is here. -
johnd at 10:20 AM on 17 March 2011Maize harvest to shrink under Global Warming
Rob Painting at 09:00 AM, whilst I understand the purpose of the trials which is reflected in the majority of trial sites being in areas where maize is less commonly grown, it seems that the negative response to increased temperatures was not evident or very low in those areas where maize is more commonly grown. The two main areas seem to be are the region in the vicinity of Johannesburg and southern Nigeria which interestingly have different average growing temperatures with southern Nigeria at about 25°C being about 5°C higher than the main area near Johannesburg. If the findings of the study were applicable to those areas, then the yields of those crops in southern Nigeria must be only a small % of those around Johannesburg If it is not rational for technology to fix everything, is it rational to expect that maize should like temperatures over 30°C when, whilst it is grown in a wide range of conditions, the area where the greatest % of land is utilised for maize in Africa is in a more temperate zone? Also, if maize was previously thought to be tolerant of warming, was there any real foundation for such opinion, and if so on what was it based? -
adelady at 10:18 AM on 17 March 2011One of the best climate change ads I've seen
Excellent, John. Some people are really clever. I wish I'd thought of such a simple illustration - how to link heat-> melt-> sea level rise. And have it attractive enough for people to look at it long enough for the image and its message to stick. -
Gilles at 10:18 AM on 17 March 2011Republicans to Repeal Laws of Physics
JMurphy : I am not working with analogies. Each issue is to be examined separately. Do you have a precise assertion concerning creationism that you would try to convince me about ? do you have a precise assertion concerning global warming that you would try to convince me about ? I will examine each one seriously and I will tell you what I'm thinking of them. I never said that the existence of a peer-reviewed journal was a proof of veracity - me. "Well, one more try... Gilles, when you say that you are unable to make the determination yourself, but these people say X, that is a style of argument called an appeal to authority, whether you recognise it or not." No it's not, because I not claiming that something is true because somebody said it. I said some issues are open. That's different. " a) That's not true; Jim Hansen has proposed a phased-in carbon tax that would provide the mechanism to wean us off of fossil fuels without causing a crash." May be Hansen is a magician. I suggest him to teach chinese people how to develop without coal. b) "It's irrelevant; it's not really the climate scientists primary responsibility to say how we should reduce FF use. Their primary responsibility is to determine if there is a serious problem, and the consensus is 'yes', there is." I think there is a serious problem with car crashes , which kill a million people a year. It's scientifically proved - actually very easy to prove. Nobody contests it ! no contrarians, no denialist, for sure it's true. So i deduce that we should immediately ban all cars and stop making them. Do you agree ? what does Jim Hansen think of it ?Moderator Response: [DB] This has strayed far enough off-topic. -
RW1 at 10:14 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
Protector (RE: 585), "I mean total down-welling long-wave radiation ..." It has to be separated, because what is determining the GHE and surface temperatures is precisely the amount of surface emitted that is coming back from the atmosphere. -
Albatross at 10:11 AM on 17 March 2011Maize harvest to shrink under Global Warming
Rob @15, It is worrying that a C4 crop (i.e., maize) does not fare well under high temperatures, b/c C4 vegetation has (up until now at least) tended to cope quite well with high temperatures. It also struck me in their Figure 3, that the Sahel region (an important crop producing region) is also expected to suffer yield losses under higher temperatures. Also, AFAIK, maize is also a staple crop in Africa. People also tend to forget that much of the farming in Africa is subsistence-type farming, and thus much more at the whim of heat, drought and flood. As an aside, apparently Canola also does not like temperatures above 30 C. From a paper by Kutcher et al. (2010, Agricultural and Forest Meteorology): "Iterative Chi square analysis and iterative principal components analysis both showed that the beginning of July, which coincides with the early part of the flowering period of the crop in SK [Saskatchewan, Canada], was the critical time in which high temperatures (>30 C) and low precipitation led to yield loss." -
Protector at 10:04 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
RW1 @ 584: I mean total down-welling long-wave radiation ... -
RW1 at 09:50 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
Protector (RE: 582), "1) Back radiation has a marginal influence on surface temperature due to the effect of convection;" If by 'back radiation' you mean downward emitted radiation that last originated from the surface emitted, then NO. -
RW1 at 09:46 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
Tom Curtis (RE: 559), "the total IR radiation from the atmosphere to space is 199 w/m^2. Of that, 6.4 w/m^2 will have been transported to the atmosphere by thermals, 29.2 would have been absorbed SW radiation, and 29.9 would have been carried into the atmosphere by convection." Let's run these numbers and see if they work: If 40 W/m^2 passes through the atmosphere, that leaves 199 W/m^2 emitted by the atmosphere, yes. 199 W/m^2 - 36.3 W/m^2 (6.4 + 29.9) emitted out to space from thermals and evaporation = 162.7 W/m^2. That leaves an additional 162.7 W/m^2 to be emitted. If you assume 29.2 W/m^2 (37.4%) is emitted directly from the 78 W/m^2 of the energy the atmosphere absorbs from the Sun, that leaves 133.5 W/m^2 that must come from surface emitted IR. It also means 48.8 W/m^2 (out of 78 W/m^2) total is radiated down to the surface. 161 W/m^2 is absorbed directly by the surface. 396 W/m^2 - 133.5 emitted to space = 262.5 W/m^2 emitted down to the surface. 161 W/m^2 + 262.5 W/m^2 + 48.8 W/m^2 + 60.7 W/m^2 = 533 W/m^2 (396 W/m^2 required). These numbers don't work. -
Chris G at 09:37 AM on 17 March 2011Republicans to Repeal Laws of Physics
Well, one more try... Gilles, when you say that you are unable to make the determination yourself, but these people say X, that is a style of argument called an appeal to authority, whether you recognise it or not. "so why don't you stop using ANY fossil fuel just tomorrow ? " And, that style of argument is called a strawman. No one is claiming that we should cease all fossil fuel use immediately; so, whatever point you are trying to make is moot. "The vast majority of authorities don't have any idea how to stop FF without an immediate economic crash, and nobody even think of that ." a) That's not true; Jim Hansen has proposed a phased-in carbon tax that would provide the mechanism to wean us off of fossil fuels without causing a crash. b) It's irrelevant; it's not really the climate scientists primary responsibility to say how we should reduce FF use. Their primary responsibility is to determine if there is a serious problem, and the consensus is 'yes', there is. Before you start an argument about the consensus, you should come to grips with the idea that the consensus came to exist as a result of the research, not the other way around. I'm neither a scientist, nor a policy maker; so, it isn't my job to answer your last question. It is the job of the policy makers deal with what the scientists are telling them about the nature of the problem, and that is what this group is trying hard not to do. They just want to ignore it. Not find it wrong, just ignore it. -
MattJ at 09:16 AM on 17 March 2011Examining the impacts of ocean acidification
There is one passage from this long article that I think is particularly valuable, something we can use as our basic message as we focus public attention on this issue. That is: "These and creatures like them are at the base of an ocean food chain, and they are already seriously damaged. If they are lost, it is not just biodiversity we are losing, but our food supply as well." That people will understand, that underlines how important this really is. -
carbonfootnotes at 09:02 AM on 17 March 2011Examining the impacts of ocean acidification
Great post, overlooked issue. On my way to watch the vid now. Thanks. -
Rob Painting at 09:00 AM on 17 March 2011Maize harvest to shrink under Global Warming
SNRatioThere are too many parameters which I think are not properly controlled here. Adaptations in genetics, growing techniques etc may to some extent mitigate
The whole purpose of the trials was to identify varieties of maize that were robust i.e.selecting those genes which would better suit the harsh African conditions. Despite this a consistent response was found; maize don't like temperatures over 30°C. I don't think it's rational to expect the "technology fairy" to fix everything. -
Protector at 08:59 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
To ALL: I'd like to get the discussion back to the topic at hand, the Greenhouse Effect, if I may (since this is so fascinating!). I'm curious to know, if there is a broad consensus among this group about 3 aspects of the GH effect discussed above by Tom Curtis, damorbel, and myself. Since these revaluations were a real surprise to my level of understanding, I thought I'd make sure that the other expects support them as well: 1) Back radiation has a marginal influence on surface temperature due to the effect of convection; 2) Temperature lapse rate in the troposphere is controlled by convection through the vertical pressure gradient, and is not affected much by GH gases; 3) GH gases affect surface temperature only indirectly through controlling the temperature of the emission layer (where most IR radiation escapes to space) in the upper troposphere. Are those correct? I appreciate your input!Moderator Response: [DB] Tom Curtis has my complete and utter confidence. -
idunno at 08:50 AM on 17 March 2011And so castles made of sand fall in the sea, eventually
Hi Michael, My understanding of the physics of dissolved gases and frozen chemicals such as methane clathrates at pressure is limited to say the least. I have done the PADI divemaster course, but that doesn't make me any kind of an expert. I do have a gut feeling that the temperature rise is already so great that the sea level rise would have to be in the range of 20 to 30 metres of water for the "clathrate stability zone" in the East Siberian shelf, and other locations, to be truly stable. This should perhaps be a worry to your students, to you and to Dick Cheney. As you are doubtless aware, the floating Arctic sea ice is disappearing. As this goes, the extra heat within the Arctic ocean will increasingly begin to melt the sea bed - which is composed of methane clathrates. Melt one litre of frozen water (aka ice) at surface and you get one litre of liquid water. Melt one litre of frozen water (aka methane clathrate) at the sea bed and you get only 0.8litre of liquid water. You also get 168 litres of methane. For "litre" replace "cubic kilometre" and you're dealing with the right units. If any of your students might be able to persuade me that I shouldn't be scared witless by this, I would really like to hear from them. Methane-lake level rise may precede sea level rise. Additionally, methane in sufficient concentrations is both poisonous and explosive. -
carbonfootnotes at 08:36 AM on 17 March 2011Maize harvest to shrink under Global Warming
I literally just finished reading Lester R Brown's 'World on the edge' a few hours ago - this problem is a main theme and I recommend you check his book out. Food security is intertwined with so many issues attached from climate change, both its causes and results. -
Albatross at 08:24 AM on 17 March 2011Republicans to Repeal Laws of Physics
Gilles @167, Nice try, but you seem to have missed my closing statement @162, which read: "Giles, I am not going to continue debating with you, and [thereby] providing you a platform to perpetuate your misinformation." I'm not biting. -
Philippe Chantreau at 08:19 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
Damorbel, "just the reason why jet transports like to fly in the stratosphere." You should have explored this more before throwing it in the discussion as if it was fact. At mid latitudes, the average height of the troposphere is 17 km, it gets higher toward the equator, lower toward the poles. At our latitudes, transport jets fly mostly between 8 and 13 km (25 to 42000 ft pressure altitude). A number of business jets are designed to handle transonic speeds and can be comfortably flown up to 50000 ft or even higher. However, they are not true stratospheric airplanes. Even commercial transport jets operate on a relatively thin margin of safe airspeed. As air density decreases, an aircraft needs more and more speed to generate lift, edgeing close to the speed of sound. At high altitudes, the difference between stall speed and maximum speed for the aircraft's design (beyond which flight controls may become ineffective) becomes small enough to be a concern. Stratospheric flight requires specific design or the ability to go supersonic. Modern transport jets are not designed to fly in the stratosphere and pilots do not like to go higher than 45000 feet. Not only their safe airspeed range shrinks but the risks from a decompression accident increase dramatically. In a 2 men crew airplane, if one pilot leaves his station, the other must wearing the oxygen mask, and keep it until the other crewmember returns. At 40000 feet, you have about 18 seconds of useful consciousness if you're a healthy adult. There is plenty of smooth air between 15 and 25000 feet, the reason why long range transport jets fly above 30000 is fuel consumption. When there is weather generating turbulence at these kind of altitudes, it is most likely convective in nature and can extend to 55000 ft or more, you can't beat it by climbing. -
JMurphy at 08:19 AM on 17 March 2011Republicans to Repeal Laws of Physics
Gilles wrote : "...Mcintyre has already made relevant criticisms that have been acknowledged by the community, and published reviewed papers (which is not the case of astrologists for astrophysicists or creationnists, to my knowledge)." It's easy to criticise but quite another thing to be taken seriously, as McIntyre knows. He may well have pointed out some problems with proxy data in MBH98 but, not being in any way an expert in anything to do with Climatology, he has not (indeed, cannot - in the same manner as you mention with regard to astrologists vis a vis astrophysics) been influential. Oddly, though, so-called skeptics seem to hold him in high regard and he has even been called here a "real statistician" - whatever that was meant to prove. If you want to see more 'debate' with regard to Evolution, how about this peer-reviewed journal - admittedly as scientifically trustworthy as Energy & Environment. Now, which hero to the so-called skeptics has published in E&E...? -
Gilles at 07:49 AM on 17 March 2011Republicans to Repeal Laws of Physics
" I am judging you on your inability to make a consistent, coherent and fact/science-based argument, and your inability to get your facts straight. " I'm deeply sorry you think so. So may be we could compare our "facts". For instance, let us compare our scenarios. Could you please indicate me , what would be for you * the worst scenario * the "most realistic" scenario * the "best scenario" for the XXIth century, with the following estimates : - CO2 concentration in 2100 - annual CO2 production in 2100 -annual energy consumption in 2100 - annual GDP in 2100 - average temperature increase in 2100 (with respect to preindustrial value) -
RickG at 07:49 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
damorbel @ 570 The diagram is not about temperature. Its about incoming solar radiation expressed in W/m^2 and how it is distributed throughout the Earth's climate system, which is the proper unit of measure for that particular type of energy (Incoming Solar Radiation). The 2009 diagram shows slightly different numbers from your example which was published in 1997 because the data has been updated. Why would Ternberth or anyone for that matter want to use 12 year old data when more up to date data is available? And again, the diagram is about the distribution of energy, not temperature. -
Gilles at 07:34 AM on 17 March 2011Republicans to Repeal Laws of Physics
Chris G "You are using an appeal to authority, and the vast majority of the authorities are against you." I'm sorry, but you're projecting your own attitude on me. I am not appealing any authority. I am not saying these people are always right. I observe that there is a debate, and I can give you many comments even by climate scientists showing that these people have been often right. " The only efficient way to stabilize the CO2 content of the atmosphere is to quit putting more into it. " Well said ! and the only efficient way to avoid car crashes is to stop using cars, too. so why don't you stop using ANY fossil fuel just tomorrow ? " The vast majority of authorities agree that things will get catastrophically bad if BAU continues until we run out of fossil fuels. Like Yul Brynner, at some point, we will quit using fossil fuels. The sooner we do that, the less chance we have of developing a fatal condition. The current bill would delay when we quit." The vast majority of authorities don't have any idea how to stop FF without an immediate economic crash, and nobody even think of that . So please tell me : what is the reasonable minimum amount of FF you would allow per capita, and for how long ? -
Tom Curtis at 07:30 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
damorbel @578, you are of course correct about the stratosphere. Further, without the absorption of UV by the dissociation of O2 and O3, there would be no temperature inversion in the stratosphere. However, even without that absorption, radiation rather than convection would dominate energy transfers in the stratosphere as I have described, and for the reasons given. I had considered giving the fuller explanation, but opted for brevity. -
Gilles at 07:26 AM on 17 March 2011Maize harvest to shrink under Global Warming
MattJ : I thought that the continuous of fossil fuels had increased our food production by several dozens, but again, we may not live in the same world .... -
damorbel at 07:10 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
Re #573 Tom Curtis, very interesting contribution. You are certainly correct about radiation playing a minor role in transferring energy in the bulk of the troposphere. But I have a problem with your explanation for the 'top of the trop.' I suggest it is the absorption of ultraviolet by O2 that dominates the heating of the atmosphere above the tropopause. About 10% of the Sun's radiant energy is absorbed by O2 and of course the resultant O3. This 'stratospheric heating' occurs even with the rather small amount of UV energy because the density of air is so low 'up there'. And, being a heating effect and causing the temperature to rise, it produces what is called, in the troposphere, a temperature inversion, a condition with warm air over cold, known to supress convection and produce stable air conditions, just the reason why jet transports like to fly in the stratosphere. The temperature at the bottom of the stratosphere ('top of the trop.') can be -60C but it rises steadily to about 0C at 60 to 65km. -
Tom Curtis at 07:06 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
The following is a diagram to illustrate the importance of the lapse rate from one of the best simple explanations of the Green House effect that I know of. (Warning, it contains some maths; but you do not need to follow the maths to understand the explanation.)
One point the diagram illustrates which I haven't mentioned is that GHG "sets the temperature at the top of the troposphere" (which on reflection, is not the best wording) by adjusting the altitude from which the Earth effectively radiates to space at different frequencies.
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Protector at 07:00 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
Tom Curtis @ 573: Wow, that's a whole different picture from what I had in mind. Very enlightening!... So, it sound like the vertical pressure gradient is a key factor controlling the lapse rate at least in the troposphere, and then GH gases affect directly only the upper troposphere temperature, and controls the surface temperature indirectly through the lapse rate, correct? Let me ponder on this for a while before I continue this amazing (at least to me) discussion. -
Rob Honeycutt at 06:57 AM on 17 March 2011The name is Bond...Gerard Bond.
PhySci @ 18... "I have researched this topic in detail, I can tell you with full confidence that is NO credible empirical evidence in the entire historical record that CO2 has had ever any impact on Earth's climate! " I can tell you with equal (or more confidence) that there are many thousands of other scientists who have researched this in excruciating detail and have come to the conclusion that CO2 is the "largest control knob" on the planet's climate. You have a daunting uphill battle to convince the broader scientific community of your position. -
Tom Curtis at 06:55 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
Protector @572, back radiation is relatively unimportant in determining global temperatures, although situations arise where it is very important in determining the local temperature for a period of time. However, if back radiaton raises surface temperatures to far, this will raise temperatures at the top of the troposphere by convection. The raised upper tropospheric temperatures will result in more radiation escaping to space, thus cooling the Earth. In consequence, the temperture at the surface in the long term is set by: 1) The Lapse rate; and 2) The balance of IR radiation to space from the upper troposphere, as determined by GHG. You need both factors. If you consider a number line representing the surface tempertures, then the lapse rate is a sloped line intersecting the number line. The point of intersection will determine the surface temperature. However, if we just know the slope, we do not know the point of intersection. We also need to know the location of at least one other point on the slope, and that is determined by the GHG in the atmosphere. -
les at 06:48 AM on 17 March 2011Republicans to Repeal Laws of Physics
160 Moderator Yes, well. No engineer understands all the processed of combustion in a piston; and certainly not without the help of models and simulations. This uncertainty is surely enough to stop someone, inclined to that kind of thinking, to stop driving a car. -
Tom Curtis at 06:47 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
Michael Sweet @571, damorbel is using the correct units, and the approximate value of the environmental lapse rate, which is critical to the greenhouse effect. (See my comments at 563 and 573.) Where he is wrong is in supposing that Trenberth's diagram from the IPCC is a model of the greenhouse effect. It is not, except in the most rudimentary terms. It is only what it claims to be, the Earth's energy budget, ie, a tabulation of what comes in and what goes out. His demand about the proper presentation of the table amounts to a demand that every diagram related to a theory should explain every feature of the theory, which is absurd. -
Tom Curtis at 06:42 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
Protector @569, very happy you are finding it useful. The air heats as it falls because it is compressed by the higher pressure air around it. It cools as it rises because it expands because of the lower pressure air around it. This is an indirect effect of gravity, which is of course the reason the air becomes more dense, and under higher pressure the lower you get in the atmosphere. GHG also impose a lapse rate on the atmosphere, however, in the troposphere, the effect of convection overwhelms that of GHG in determining the lapse rate because it takes much less time for convection to move energy than it does radiation. Radiation counter intuitively takes a long time to move energy because it only travels a short distance before being absorbed. It will then take considerable time before it is re-emitted. So, while convection carries energy quite slowly, and radiation carries it very fast (at the speed of light), convection carries it in one continuous motion, while the radiation makes a series of short journeys with very long delays in between. The tortoise and the hare come to mind. At higher altitudes, because the molecules are greatly seperated radiation becomes the main means of carrying energy. But because the molecules a greatly seperated, very little of the Earth's radiation to space comes from those altitudes, so they can be effectively ignored. So, in the troposphere, convection determines the lapse rate. What GHG do is determine the temperature in the upper troposphere. By determining that temperture, they also determine the temperture at the surface because the two are related by the lapse rate. And to avoid one common confusion, this is not a case of the upper troposphere warming the surface. The sun warms the surface. The lapse rate and GHG determine how efficiently the energy from the sun can escape the surface, and hence how much the surface is warmed by the sun. -
Protector at 06:20 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
Tom Curtis @ 565 I just read your comment to PhysSci. "As a result, except for short term excursions (ie, over a few hours or in some cases days), back radiation is not very significant in determining average surface temperature. However, back radiation can lift surface temperatures up to the temperature determined by the lapse rate without the heat being dissipated by convection." I thought that back-radiation was the primary factor controlling the global surface temperature. That has been my impression all along from the popular literature describing the greenhouse effect. However, as someone has pointed out on this thread before, one cannot learn good physics from popular literature and analogies ... So, should I understand that back radiation is only marginally important for surface temperature globally because of the presence of convection? Is this another way of saying that the lapse rate is the main factor determining surface temperature? Thanks again! -
michael sweet at 06:19 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
It is amazing that someone who does not even understand the units thinks that professional scientists have been wrong about the 2nd law for 150 years. And they are the only ones who can figure it out! degrees/km, it would be funny except people like this keep us from taking any action about AGW. -
Alexandre at 06:16 AM on 17 March 2011Irregular Climate Episode 18 (featuring Dana Nuccitelli)
I have just listened to the interview. Relax Dana, you did really fine. -
scaddenp at 06:15 AM on 17 March 2011CO2 lags temperature
trunkmonkey - "Paleoclimate is really a logic excercise where you are lucky when the disparate signals from proxies give you a correlation." This simply not true. Uncertainty bands gets larger but you will find that alternative theories have to work with quite strong constraints. Suggest you read up on this. "I believe that the clear signal that temperature lead CO2 in these data is an extremely important clue that is not adequately explained by Milankovitch." And what is the basis of your belief? Certainly not published science. How come models using known physics have little problem with such data? As to whether CO2 has always led temperature, possibly but PETM is closer to what we had. Temperature increases will certainly lead to CO2 increases to amplify the effect but if another mechanism (eg burning fossil fuel) will increase CO2, then you still get the temperature rise. -
damorbel at 06:11 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
Re #541 RickG, you wrote:- "The diagram was about the flow in energy which is expressed in units of W/m^2. That is: energy (watts) over a specific area (a square meter). Are you suggesting that it should be "degrees" per square meter?" No, I'm not. Degrees per meter i.e. distance, not area. The temperature in the tropsphere (in the diagram) should be shown as -6.5C per km (altitude). Then the author could show how it is affected by CO2, it is the second law of thermodynamics. You also wrote:- "Also, why are you criticizing the IPCC when the diagram you are talking about is by Trenberth, Fasullo and Kiel (2009)? " Because the IPCC use Treberth's diagram in many of its official reports
when making the case for governmental action to reduce CO2 emissions
Trenberth has updated his diagram a number of times changing the W/m^2 numbers but never showing any temperatures or even temperature gradients. Surely if the IPPC wishes to make the case for CO2 global warming they could have chosen a diagram with temperatures on it so that the warming would be clear to all?
It a fundamental of heat transfer, W/m/K Watts per metre per degree Kelvin. You can multiply this by however many m^2 you have to determine the total power being transferred for the given temperature difference, the formula just gives the temperature gradient; in the atmosphere it is -6.5 deg. Kelvin per km.
Moderator Response: [Muoncounter] You've raised this point before. If you have an objection of substance, perhaps you can take it up directly with Dr. Trenberth and report back. -
Protector at 05:58 AM on 17 March 20112nd law of thermodynamics contradicts greenhouse theory
Tom Curtis @ 563: Thank you for this wonderful explanation! It gave me insight and more food for thought. I knew that air rises when it heats up, but did not fully realize that it also cools at the same time. I did not understand that 'compression' actually heats up the falling air. From what you said: "That [lapse] rate is a function of the gravitational acceleration and the specific heat capacity of the gas involved", I figured out that gravity is somehow responsible for compressing a falling parcel of air. Could you elaborate a bit more how exactly that works? Also, from your explanation, I gather that greenhouse gases are not determining the lapse rate. Is this right? I thought GH gases were either controlling the lapse rate or directly heating the surface, and that the lapse rate was responsible for the higher temperature on the surface. Could you provide a little more clarification on this? This discussion has been really useful for me. I feel like I'm really advancing my understanding in a field I've been taken for granted!
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