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muoncounter at 09:40 AM on 28 February 2012Fritz Vahrenholt - Duped on Climate Change
elsa#80: "In its crudest form..." So? We are not here to discuss 'crudest forms.' It is clearly a part of the overall understanding of climate that aerosols can cause significant cooling. Hence your claim of falsification of a cherry-picked part of valid science is false. You need to stop coming up these silly, pedantic objections and move on to improving your own understanding the science. Otherwise, your just wasting everyone's time. -
Postma disproved the greenhouse effect
YOGI - It would correspond to a uniform temperature of 17.4C; see the Stefan-Boltzmann law. The average temperature (~15C) of the Earth surface radiates a bit more effectively due to variations - given positive and negative variations, and the T^4 relationship for radiative power, any variations will increase the energy radiated. Please read the OP, including the reference to Selsis 2007 for airless bodies with slow rotation rates like the Moon or Mercury. This is very unlike the more quickly rotating Earth with oceans and atmosphere to distribute heat far more evenly. You are continuing to compare apples to, well, coconuts. I would strongly suggest that you read up a bit on IR absorption and the lapse rate, and how they together cause a much lower emission of IR energy to space than would occur if we did not have greenhouse gases in the atmosphere. Postma's nonsense will, IMO, not be helpful to your understanding. -
elsa at 09:31 AM on 28 February 2012Fritz Vahrenholt - Duped on Climate Change
1. Non repeatability (if that's a word) We cannot rerun the climate. By this I mean that we cannot experiment with the climate. We cannot try what the temperature would be with a given CO2 concentration because (a) we cannot fix the concentration and (b) even if we could the other things that affect climate will have changed too. 2. Modification In its crudest form the AGW theory (and I grant you this is a simplification) postulates that with rising CO2 the climate will warm. In the period 40s to 70s this not only failed to happen but probably the temperature actually declined. The usual escape route for the AGW theory is to attribute this to aerosols. Thus the theory needs to be modified. In its crudest form it has been falsified. -
Tom Curtis at 09:22 AM on 28 February 2012Satellites find over 500 billion tons of land ice melting worldwide every year, headlines focus on Himalayas
Matthew L @48: 1) Your assumption of rigid constraint of the Ocean on all sides is incorrect. The Ocean floor (except over continental shelves) is a thin layer that flexes with the addition of further mass to the Ocean. The effect is to slowly push magma from under the Ocean floor to under the Continental crusts, thereby pushing them up. With the reduction in steric sea level rise over the last few years, and the increase in sea level rise due to the melting of glaciers, ice sheets and ice caps, this will have been a more important effect over recent years. Unfortunately I am unable to quantify it for you, and it will explain only a small part of the reduced rate of increase of sea level. 2) There has been a distinct decrease in steric sea level rise over recent years. That is due in large part to the deep solar minimum over the period 2008 - 2011. In fact, from the 2001-2002 peak, TSI has declined by about 0.25 W/m^2 averaged over the Earth's surface, or about a quarter of the average Top Of Atmosphere energy imbalance over the last few decades. Evidence suggests a further 0.25 W/m^2 reduction from other sources since about 2004 with possible reasons including the impact of aerosols from industrial expansion in China and India, possible slight changes in TOA energy balance due to the effects of ENSO, or even a very slightly enhanced solar effect due to Solar specific feedbacks. SFAIK, the exact balance of reasons is still unknown, and nor is it known that all possible candidates are even being discussed. 3) Finally, the very large dip in sea levels from 2010 - 2012 is attributed to increased land storage of water due to the very wet 2010-2011. According to the IPCC, 100 Gigatonnes of water will result in 0.28 mm of sea level rise. The dip is just over 5 mm at its deepest, and therefore represents just over 2,000 Gt of water stored on the land surface. -
skywatcher at 09:22 AM on 28 February 20122012 SkS Weekly Digest #8
Based in Australia. I'll regularly check up on: RealClimate Open Mind Neven's Arctic blog Deep Climate (BTW, an interesting new post on how GMU have just released their very tardy and weak fndings on the Wegman scandal, and a hypothesis that they did so under the cover of the Heartland fiasco - "good day for bad news"?) I might also pass by Deltoid, Science of Doom, Rabett Run and keep an eye out for new videos from ClimateCrocks and potholer54 (Peter Hadfield) - both often superb video debunkings. -
neil at 09:14 AM on 28 February 2012Search For 'Missing Heat' Confirms More Global Warming 'In The Pipeline'
@ Rob 51 I did not say the IPCC failed to consider carbon-climate models. I said the fully-coupled models were predominantly 'physical' models only, with no carbon cycle which is true. For example, this list gives the 23 AO GCMs used in CMIP3 / AR4. I also said in my previous post that some models (mainly intermediate complexity models, not full AO GCMs) like UVic, Bern and Climber etc did have carbon cycles. This is exactly what your link above shows (11 models, from C4MIP), so we agree here. I fully agree about uncertainties in the land-carbon storage etc of the models; but for the C4MIP model configurations (as listed your IPCC table), the carbon-climate response (thus warming from past emissions) is basically constant in time on scales from hundreds to thousands of years (as shown in Mathews et al. 2009), which is the point that I have been making all along. Again, for the umpteenth time, I give you that there is an 'aerosol' based warming in the pipeline, but not one from the carbon cycle, based on the C4MIP/AR4 generation of carbon-climate models. About the ocean heat ; yes there are many terms in the heat budget. I never said heat only travels downwards, I was saying the net of all these terms is a downward heat flux. If you do not agree that there is a net downward heat flux in the ocean under global warming, I just don't know what to say. In fact, I think we agree on almost everything, I was just trying to politely point out that the C4MIP models, with constant aerosols, show no 'warming in the pipleline' for past emissions on medium to long timescales, as documented amply in the literature. I feel that more than anything I've been attacked for this, rather than engaged, so at this point I'm going to withdraw from SKS. -
JP40 at 09:06 AM on 28 February 2012Global Extinction: Gradual Doom as Bad as Abrupt
Building a giant server bank on the moon, or even a self-sufficient colony, isn't future technology. We had the technology to go there 40 years ago. It is only a matter of someone with enough money and power deciding not to be greedy, which ,as you observed, isn't likely. However, if anyone reading this blog happens to be a political leader of a large country or a billionaire, I beg you to invest in our future. -
YOGI at 09:03 AM on 28 February 2012Postma disproved the greenhouse effect
KR The daylight figure for the Moon is the same as near Earth space maximum temp` at 121 degC, while the Lunar night figure is affected by warmth from the Lunar surface so is higher at the equator and lowest at the poles. The maximum temp is just a direct sunshine figure that you can take on the Moon or in near Earth space, so it`s apples and oranges. What temperature does 396 W/m^2 correspond to ? -
Riccardo at 08:45 AM on 28 February 2012Postma disproved the greenhouse effect
YOGI "With an albedo of 0.12, we actually receive more IR than visible from the Moon." Could you please elaborate a bit? I'm really missing the logic. -
Postma disproved the greenhouse effect
YOGI - The average temperature on Earth is ~288K. The average temperature on the Moon is ~218K. Averages reflect the total incoming energy and radiative effects, not peak or nadir temperatures. Note the difference between the averages? The amount of energy radiated from the top of our atmosphere is ~240 W/m^2, corresponding to a temperature of ~255K for a blackbody. This is due to the greenhouse effect, to greenhouse gases radiating from the top of the atmosphere, and to the atmospheric lapse rate which requires a much warmer surface (radiating ~396 W/m^2) to radiate the incoming solar energy back to space at TOA. Rosco was completely incorrect - Postma's work is nonsense. I suggest you do some more reading. -
YOGI at 08:36 AM on 28 February 2012Postma disproved the greenhouse effect
Sphaerica "..the surface of the moon reflects a large amount of the light (as proven by how bright it is when viewed from the earth at night)" With an albedo of 0.12, we actually receive more IR than visible from the Moon. -
Bob Lacatena at 08:32 AM on 28 February 2012Postma disproved the greenhouse effect
Yogi, Please forgive me if I don't take anything you say at all seriously. -
YOGI at 08:19 AM on 28 February 2012Postma disproved the greenhouse effect
Rosco is correct (roughly). The maximum temperature measured in near Earth space is 121°C, that is what is being measured on the Moon, not the Moon`s actual temperature, which is in it`s soil, not in the vacuum of space above the surface. Clearly, when maximum daytime temp is measured on Earth in direct sunshine, the atmosphere is impeding warming, not amplifying it. -
ubrew12 at 08:03 AM on 28 February 2012DenialGate - Highlighting Bob Carter's Selective Science
Citizens invest money and labor into their economy. They do this selfishly, as they expect a positive return on their investment. They follow an investment philosophy, in hopes of maximizing that return. Thus, the state of the economy is a referendum on that economic philosophy. If the global economy is in a shambles, its a simple and blunt verdict on the economic philosophy that dominated the previous 10-30 years. As it turns out, that economic philosophy is the 'free market, supply-side, deregulation' philosophy. In America, for example, income taxes have never been lower, the wealthiest 1% have gone from owning 20% of the country in 1979, to 40% of it now, and union membership has dropped by a factor of three. Reaganomics, Globalization, 'end of welfare as we know it', finance sector deregulation, Bush tax cuts, Greenspan low interest rates, 'irrational exhuberance', 'financial innovaton', largest ever housing and derivatives bubbles: all point to a country on a 'free market' deregulation binge (matched, to a lesser extent, by the rest of the world). So, by this economic philosophy, we invested in our future. How did that investment turn out? Behold: the greatest recession since the Great Depression, with likely worse on the way, and led by a meltdown in the most 'free market' sector of the economy, the finance sector. So, when a 'free market' think-tank like Heartland Institute wants to propagandize our children into doubting the work of scientists, the irony is too rich. These are primarily economic thinkers, whose economic philosophy has just led to the greatest economic meltdown in 80 years, and we're supposed to trust them on climate? Personally, I don't think even Lewis Carroll could have imagined this situation. -
Bob Lacatena at 07:57 AM on 28 February 2012Postma disproved the greenhouse effect
It's actually a nice, convoluted little bait and switch they pull, and what's really, really, really funny about it is they have to violate the 1st law of thermodynamics for it all to work... while all the time screeching that GHG theory violates the 2nd law of thermodynamics. You see, pressure is determined by density is determined by gravity, which is determined by distance from the center of the earth, so closer to the surface the pressure is higher. Who can argue with that? And any high school chemistry student learned that for an (ideal) gas, PV=nRT. So... temperature is proportional to pressure. So if the sun heats the planet to 255˚K with constant sunshine, then... clearly as the pressure gets greater nearer the surface, the temperature must rise above that! It's all so simple. Who needs that radiative greenhouse mumbo-jumbo anyway? -
dana1981 at 07:43 AM on 28 February 2012DenialGate - Highlighting Bob Carter's Selective Science
KR - if that's the case, I'd certainly agree! -
Camburn at 07:35 AM on 28 February 2012Satellites find over 500 billion tons of land ice melting worldwide every year, headlines focus on Himalayas
scaddenp: A La Nina or El Nino event is only noise in the rate of rise of Sea Level. Even if you considered last years La Nina to be wet, the water has long since gone back to the ocean. We know with certainty that Greenland has lost ice mass. As a percentage of total mass, the loss is very small but the result is still a loss of mass and an increase in volume of water in the ocean. This is a long term trend that is not changing. The rate of SLR has slowed down over the past 5 years. ARGO data, while short, shows a reduction in THC of the oceans in the 0-700M volume. As you can see from the following link, even a 10% increase in freshwater is not a significant amount when looking at all of earth's water. The Water CycleResponse:[DB] "ARGO data, while short, shows a reduction in THC of the oceans in the 0-700M volume."
Kindly provide a link that supports this assertion...
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actually thoughtful at 07:14 AM on 28 February 20122012 SkS Weekly Digest #8
In the them of being off topic - I have noticed two things about moderation that appear easy to fix: 1. Authors "moderating" their own posts 2. Moderator who wrote the original post have trouble staying as objective as possible. I recommend not having the original author moderate their own posts.Moderator Response: [JH] Like "beauty","objectivity" is in the eye of the beholder. PS - Not all SkS authors have volunteered to serve as Moderators. -
Alexandre at 07:07 AM on 28 February 20122012 SkS Weekly Digest #8
Besides SkS, I regularly look at RealClimate Open Mind Science of Doom Nasa GISS and RoySpencer for monthly temp anomalies NSIDC for sea ice extent Ok, that's six. I only visit Nasa, RS and NSIDC about once a month. -
DenialGate - Highlighting Bob Carter's Selective Science
dana1981 - Perhaps he doesn't consider his opinions re: climate change to be "research"? -
dana1981 at 07:06 AM on 28 February 2012DenialGate - Highlighting Bob Carter's Selective Science
Neven - Carter seems to have a very odd definition of "special interest organization":"He receives no research funding from special interest organisations such as environmental groups, energy companies or government departments."
Apparently political think tanks don't qualify? How convenient. -
Neven at 07:02 AM on 28 February 2012DenialGate - Highlighting Bob Carter's Selective Science
And don't forget that according to Carter's bio he "receives no research funding from special interest organisations". -
scaddenp at 06:49 AM on 28 February 2012Satellites find over 500 billion tons of land ice melting worldwide every year, headlines focus on Himalayas
"ENSO has no effect on the volume of water in the ocean" - yes it does. The recent removal of water to land for instance in the La Nina, affecting sea level. -
scaddenp at 06:23 AM on 28 February 20122nd law of thermodynamics contradicts greenhouse theory
YOGI - as SoD explains, the example is chosen because it is easy to calculate and shows how the insulation doesnt violate 1st Law. That is the point, no more. -
scaddenp at 06:10 AM on 28 February 20122012 SkS Weekly Digest #8
My ones - "A few things ill considered", for the news/papers round up; Realclimate; Science of Doom; and Tamino. I also look at Blackboard and Roy Spenser as the more honest of the "skeptic" world so I dont get tunnel vision. -
Rob Painting at 05:59 AM on 28 February 2012The Deep Ocean Warms When Global Surface Temperatures Stall
Muon - of course I'm jumping the gun, the length of the record, as discussed in that post, isn't long enough to to say definitively. But the error bars will reduce as the length of observations grows, that much is a gimme. -
Postma disproved the greenhouse effect
Nonsense, Dikran - your posts contain (ahem) significantly more content :) -
Dikran Marsupial at 05:54 AM on 28 February 2012Postma disproved the greenhouse effect
KR, nice explanation; the difference in clarity between your answer and mine is why I tend to keep to statistical issues! ;o) -
Postma disproved the greenhouse effect
The "gravitational heating" meme is one I've seen over and over. I would suggest it as a topic for a SkS thread, except that it's so ridiculous I feel it a waste of time. Gravitational collapse can release energy - once per collapse. Once that happens, the energy is free to radiate away as per the Stefan-Boltzmann law, and it's quite clear that over the 4.5 billion years of Earth's existence all of the excess energy from the atmospheric collapse would be long gone. But such collapse cannot provide a continuing flow of energy. -
Matthew L at 05:53 AM on 28 February 2012Satellites find over 500 billion tons of land ice melting worldwide every year, headlines focus on Himalayas
Muoncounter: "But I take issue with the prior comparison to warming a test tube, resulting in all vertical expansion. Continental shelves do not have vertical sides; the areal inundation of just a few meters of sea level rise is very large." Point taken, but we are talking about a rise of just a few millimetres not metres. I doubt the reduction in the rising trend has anything to do with "inundation" of river deltas at these tiny levels. It is much more likely to do with the temperature of the oceans not rising as fast. -
Matthew L at 05:46 AM on 28 February 2012Satellites find over 500 billion tons of land ice melting worldwide every year, headlines focus on Himalayas
Sphaerica: I'm not at all certain of myself here, but my initial point was that if you add enough energy to a bucket of water to raise it by 1 degree, will that expand as much as if you added that same amount of energy to a pool of water? Hmmm... not sure if that is the right question! In the case of the ocean the bucket (upper levels) and pool (lower levels) have the same surface area. So the better question might be "if you add enough energy to a bucket of water to raise it by 1 degree, will that expand as much as if you added that same amount of energy to a bucket of water that is deeper?" To which my answer would be "Yes" (as far as I understand it) even though the temperature of the water in the bucket rises less. "The question was, given that level of pressure, would an increase in temperature result in an equivalent or lesser increase in volume compared to a liquid at a lower pressure." Water at a higher temperature (up to 45c) is even less compressible so the effect of high pressures really has no significant effect on what happens when water is warmed slightly in the deep oceans. All of this may be moot, however... your graph of decreasing sea level trend does not seem to take into account other "noise" factors, such as the effects of ENSO events. Are you certain that the decreasing trend you see is real? This data set has the intra-annual seasonal effects removed and my 12m moving average removes monthly noise. However it does include the effect of any ENSO events. Because the analysis is done over 5 years any ENSO "spikes" or "dips" are somewhat delayed. For instance the El-Nino in 1998 is reflected in an up-tick in the graph in 2003 (this was confirmed to me by the University of Colorado). I am certain the downward trend is real but uncertain as to its cause. The most likely explanation would appear to be a reduction in the rate of rise in heat content of the oceans. This seems to verify the graphs of ocean heat content that show a levelling off in the most recent period. -
Dikran Marsupial at 05:34 AM on 28 February 2012Postma disproved the greenhouse effect
Cheers Sphaerica. I noticed that Postmas paper lapsed into all the lapse rate nonsense. The idea that there is gravitational heating seems like nonsense to me. If gravitational heating were true, then it should be heating the surface even if the sun were to stop shining. My intuition here would be that it wouldn't, the Earth would cool and the atmosphere with it, until it eventually condensed out as ice on the surface and we would have no atmosphere at all. It is only the heat we recieve from the sun that holds the atmopshere up by providing the thermal energy that causes it to have pressure due to the movement of the molecules. It seems to me that Postma has got it completely the wrong way round. -
muoncounter at 05:28 AM on 28 February 2012Satellites find over 500 billion tons of land ice melting worldwide every year, headlines focus on Himalayas
Sphaerica#49: Thermal expansion varies with temperature, not with quantity of heat added. So you are correct, a fixed quantity of heat added to a bucket will result in a higher percentage of volumetric expansion than in a pool. Unless I am reading this table incorrectly, the coefficient of volumetric expansion for sea water increases with pressure, but decreases with temperature. Result: not much difference between warm surface water and cold depths. Compare coefficients of 244x10-6/K at 0C and 1000 atm pressure (deep water) vs 250x10-6/K at 20C and 1 atm pressure (surface). But I take issue with the prior comparison to warming a test tube, resulting in all vertical expansion. Continental shelves do not have vertical sides; the areal inundation of just a few meters of sea level rise is very large. -
Bob Lacatena at 05:20 AM on 28 February 20122nd law of thermodynamics contradicts greenhouse theory
1387, Dikran, I posted a response to you on the proper thread on Postma. -
Bob Lacatena at 05:19 AM on 28 February 2012Postma disproved the greenhouse effect
Dikran, Postma's paper, in the end, waters down to two things. First, he misuses the term "thermodynamics" repeated, treating it more as an incantation to ward off evil spirits than as an actual, applicable argument. He doesn't reference real thermodynamic "laws." He just throws the word around whenever and however he pleases. So after throwing around the word thermodynamics as many times as he can, then acting as if he has proven something and so can dismiss radiative effects, he gets to the real heart of his argument, which is that lapse rate is entirely defined by gravity, and explains the temperature of the surface of the earth. But here is the real gem of his smoke and mirrors act. What he does now is to do a basic, wikipedia derivation of lapse rate proportional to gravity, which of course gives the wrong answer. He then instead substitutes in the environmental lapse rate, which is the observed lapse rate. He picks a point in the atmosphere which is really arbitrary (he justifies it by saying it's the point where the atmosphere radiates at 255˚K, but that's the nifty legerdemain, because it doesn't actually matter where he started, he'll still get the same answer). Then he works down, and lo and behold, the surface temperature of the earth comes out correct! So... he dismisses radiative theory by using the word "thermodynamics" as many times as he can, couched in a lot of gibberish which is nothing more than a (poor) restatement of basic atmospheric physics, and then he goes on to introduce a superior theory, which he proves by getting the right answer... except he constructed his equation from observations, so he had to get the right answer! What he actually proves is that temperatures computed from lapse rate observations match observed temperatures. Interestingly, he does not address the elephant in the room. What happens to the energy that is radiated from the surface of the earth at 288˚K? Where does it go? Why does it not escape into space, to be seen by passing alien spaceships that can then remark "wow, that place is nice and toasty, we should visit some day, don't you think?" Postma establishes that the surface of the earth is 288˚K because of gravity and pressure, and everyone knows that PV=nRT. But he stops there and fails to explain how the atmosphere avoids then cooling from that point on, because it must be radiating at 288˚K! -
Camburn at 05:07 AM on 28 February 2012Satellites find over 500 billion tons of land ice melting worldwide every year, headlines focus on Himalayas
A change in pressure, such as increaseing pressure in hydralics, will generate heat. My send was too quick. A change in pressure, such as increaseing pressure in hydralics, will generate heat. The heat generated is a result of an external force tho, and work is being done, hence the generation of heat. -
Camburn at 05:06 AM on 28 February 2012Satellites find over 500 billion tons of land ice melting worldwide every year, headlines focus on Himalayas
Sphaerica @49: ENSO has no effect on the volume of water in the ocean. The THC of the ocean does not change with an ENSO event, it is distributed differently. AS Matthew L. pointed out, the volume of a liquid changes very little under pressure. The basis of working hydralic usage depends on this fact. A change in pressure, such as increaseing pressure in hydralics, will generate heat. The ocean bottom pressure has to be stable, as the actual volume of water does not change significantly. The top thermal layer may expand and contract, but the volume by density would stay the same unless one adds volume. The little percentage change of water on land on a long term basis as a percentage of volume of the ocean is insignificant. -
YOGI at 05:05 AM on 28 February 20122nd law of thermodynamics contradicts greenhouse theory
scaddenp#1362 That`s just a 30kW oven. The radiative transfer is all outwards, there is no energy within the middle PVC wall returning to make the inner surface hotter. Its not much different to say the maximum surface temperature that the Moon or any object in near Earth space can get to, which is 121°C. If you get closer to the Sun it gets hotter, which would be the analogy of a thicker wall on the PVC oven. -
Dikran Marsupial at 05:00 AM on 28 February 20122nd law of thermodynamics contradicts greenhouse theory
Cheers Riccardo, thought experiments are always very handy in testing out ones intuition about these things, and that one is very neat. As I mentioned earlier, Postma's example violates Kirchoffs laws, but he then goes on to use Kirchoff's laws later in the paper, so it isn't as if he didn't know them. This seems to me to be the sort of lack of self-skepticism that leads to Dunning-Kruger syndrome; presumably once he had an example that he thought he could use to argue the GHE violated the second law of thermodynamics, he didn't stop to consider whether it [his example] violated the first law of thermodynamics! -
Camburn at 04:59 AM on 28 February 20122nd law of thermodynamics contradicts greenhouse theory
All very good expanations etc above, but I think YOGI has to accept that all matter is trying to achieve a temperature of absolute zero. It is continuously cooling, and it doesn't care what direction it sheds its emissions. IF he can't accept that basic fact, then he will never understand. -
Bob Lacatena at 04:55 AM on 28 February 2012Satellites find over 500 billion tons of land ice melting worldwide every year, headlines focus on Himalayas
48, Matthew L, I'm not at all certain of myself here, but my initial point was that if you add enough energy to a bucket of water to raise it by 1 degree, will that expand as much as if you added that same amount of energy to a pool of water? We're not increasing the temperature by the same amount... we're adding the same amount of energy, which because one body is larger (pool vs. bucket, ocean depths versus surface) will not increase by the same amount in temperature. As to your formula for the volume of a liquid, I was hoping to see something with both pressure and temperature terms. The question was, given that level of pressure, would an increase in temperature result in an equivalent or lesser increase in volume compared to a liquid at a lower pressure. Stated more clearly, if you apply X joules of energy to a small volume of water at a low pressure, how will the difference in volume compare to adding that same amount of energy to a larger volume of water under high pressure. All of this may be moot, however... your graph of decreasing sea level trend does not seem to take into account other "noise" factors, such as the effects of ENSO events. Are you certain that the decreasing trend you see is real? -
Riccardo at 04:50 AM on 28 February 20122nd law of thermodynamics contradicts greenhouse theory
Dikran immagine to have a box made of ideally absorbing material (emissivity=1). An object (a black body itself) inside the box and in thermal equilibrium with it receives from the walls as much energy as it radiates. Now, take a piece of the wall (or the whole of it) away and replace it with a mirror (ideally emissivity=0). In thermal equilibrium the mirror will reflect back to the object as much energy as the absorbing wall was emitting. So, the object will receive exactly the same energy as before.(*) Maybe Postma thinks his example describes a similar situation. Though, in his example the black body is not inside a cavity. He apparently does not note the (foundamental) difference. In doing so, he breaks the First Law of Thermodynamics. Definitely the object will warm more, as you say. Like turning the central heating on while the fireplace is running. (*) The way I described the thought experiment is not strictly correct but (hopefully) gives the idea. This reasoning is not mine, the correct description is part of the work published by Kirchhoff himself when demonstrating his well known law. Good old physics, I'd say. Rerference: Philosophical Magazine, v. XX, n. CXXX, p. 1, 1860, "On the relation between Radiating and Absorbing Powers of different Bodies for Light and Heat" -
David Kirtley at 04:23 AM on 28 February 20122012 SkS Weekly Digest #8
Thanks JMurphy, for the extra info. I looked through Lindzen's presentation and it looks like the same old stuff, hardly the "devastating testimony overturning the global warming hoax" promised by the American "Thinker" headline. Sorry, moderators, if this is hijacking the post. -
Matthew L at 04:20 AM on 28 February 2012Satellites find over 500 billion tons of land ice melting worldwide every year, headlines focus on Himalayas
”First, the volume of water involved in this in the deep ocean is huge, so you are distributing that heat over a very, very large volume of water. As such, the per-mole addition of heat, and hence any expansion, is very, very small.” I don’t think that is the case. The sea is constrained on all sides by the crust of the earth, except at its top where it meets the atmosphere. Therefore any expansion or contraction can only happen in a vertical dimension (if you ignore the minor effect of flood plains and deltas). This negates the effect of an expansion in a larger volume being less than that of a smaller volume. For instance if you increase the heat content of water in a test tube by a fixed amount it will rise the same distance whether the test tube is 1m long or 10m long. Think about it! In that situation, as I understand it (happy to be corrected) if you increase the heat content of the top 10% of the ocean by 20 gigajoules (totally made up number!) it will expand vertically just as much as if you use that same energy to increase the heat content of the bottom 90% of the ocean. Sure, the temperature will rise much less, but there is much more of the sea being heated. ”Second, the water in question is under intense pressure, so I think the percentage increase in volume will be greatly reduced. I know very little about the behaviour of liquids, however, so this last is an assumption on my part, not a fact.” Actually the volume of water changes very little, even under very high pressures. That is the whole basis of hydraulic control systems. The exact formula is 5.1×10−10 Pa−1 . This is the formula at 0c, it changes even less at higher temperatures. At the average ocean depth of 3790m the pressure is 38.2 million Pascal so the water is compressed by very roughly 2%. Therefore a rise of water at sea level of 3mm translates to roughly 2.94mm at the average sea depth. Overall I think we can discount the effect of pressure on the expansion of water at deep ocean levels. So, if my assumptions are correct, and taking the reduction in the rate of sea level rise at face value, either a falling amount of water is entering the seas or the heat content is rising less quickly. Or, as has been hypothesised elsewhere, there is more water on the land. My scepticism of that final hypothesis remains, as does my final question. -
Dikran Marsupial at 04:13 AM on 28 February 20122nd law of thermodynamics contradicts greenhouse theory
Postma makes an excellent point at the top of page 12 that the blackbody equivalent temperature of 255k (-18C) is not the temperature of the surface, "but because most of the Earth's thermally emitted radiation comes from high up in the atmopshere and therefore this is the temperature you find up there" Well quite, that is exactly as AGW theory would suggest! -
Dikran Marsupial at 04:00 AM on 28 February 20122nd law of thermodynamics contradicts greenhouse theory
Thanks Tom, reassuring that my intuition was in the ball park. It is rather telling that an error in Postmas paper can be spotted by someone whose only qualification in Physics is an A-level obtained in the mid 1980s! It is interesting that my intuition "To remain at the same temperature, it would have to be radiating energy at the same rate that it is absorbed." appears to be something called Kirchoff's law, which Postma actually uses later in the paper! ;o) -
Tom Curtis at 03:54 AM on 28 February 20122nd law of thermodynamics contradicts greenhouse theory
Dikran Marsupial @ 1377, your intuition is correct. In setting up his description, Postma says:"When a blackbody absorbs the energy from light and there are no other heat or light sources around to warm it, then it will warm up to whatever temperature is possible given the amount of energy coming in from the light being absorbed. If the source of light is constant, meaning it shines with the same unchanging brightness all the time, then the blackbody absorbing that light will warm up to some maximum temperature corresponding to the energy in the light, and then warm up no further. When this state is reached it is called “radiative thermal equilibrium”, which means that the object has reached a stable and constant temperature quilibrated with the amount of radiation it is absorbing from the source of light."
(My emphasis) He has defined radiative equilibrium relative to a specific light source on the assumption that there are no other heat or light sources available. He then, as a thought experiment introduces another source of light (the mirror) and assumes the radiative equilibrium remains constant even though the presupposition of his definition is now false. To see that he has made an error, imagine that the mirror is angled to reflect the rays of an IR lamp glowing with the same intensity as the black body. Clearly in this instance the black body would warm up further. As the IR photons do not come with labels indicating their origin, it makes no difference in the thought experiment whether we use an actual IR lamp, or save on our budget by using the black body as the IR lamp because, according to the hypothesis, the IR lamp and black body shine with the same intensity. -
Dikran Marsupial at 03:49 AM on 28 February 20122nd law of thermodynamics contradicts greenhouse theory
Tom Curtis Nitpick completely accepted. The first seven pages of the paper give the impression of having been written by a student that doesn't really understand the material, and hence is full of clunky explanation that if not actually wrong, are at least misleading or confusing. muoncounter Nevermind socks, which blackbody universe keeps absorbing my car keys? I'll lookup the Azomov book, haven't read any for years. -
Dikran Marsupial at 03:44 AM on 28 February 20122nd law of thermodynamics contradicts greenhouse theory
Regarding my previous post, I suspect postma is neglecting the fact that the blackbody will have an equilibrium temperature less than that of the lighsource, which means that its temperature can still rise due to the reflected IR. It couldn't become warmer than the light source though. Readling the rest of page six and the first half of seven, I think that Postma is making the same error than YOGI was. The GHE doesn't violate the second law of thermodynamics because the NET flow of heat is always from warmer to cooler, and as a result never makes the warmer object warmer, but it does mean that its equilibrium temperature can be higher if the surface is warmed by something hotter than the atmosphere (which it is). -
Tom Curtis at 03:43 AM on 28 February 20122nd law of thermodynamics contradicts greenhouse theory
Dikran Marsupial @ 1372, a minor nit pick. Postma does not say that the black body stops absorbing light, only that the light it absorbs stops contributing towards heating the body. However, he appears to be making a bizarre claim, ie, that there is some temperature which constitutes thermal equilibrium such that, if a black body reaches that temperature it will automatically emit all light that it absorbs, where that temperature can be determined without calculating the energy balance. In fact, radiative thermal equilibrium is achieved when energy radiated equals energy absorbed, simpliciter, so he has the explanation backwards. He makes his error in the preceding paragraph where he writes:"If the source of light is constant, meaning it shines with the same unchanging brightness all the time, then the blackbody absorbing that light will warm up to some maximum temperature corresponding to the energy in the light, and then warm up no further."
Here "some maximum temperature corresponding to the energy of the light" is ambiguous. Does he mean the brightness temperature of the light? In that case his claim is false. Or does he mean that it will warm up until energy emitted equals energy absorbed? Well, then what he says is true, but he has taken several paragraphs to say in a very confused way what he could have said clearly with one sentence. Of course, his " bizarre claim" of paragraph 2 of page 5 is not bizarre at all, but merely obscure if we give the second meaning to the quoted ambiguous passage.
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