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adelady at 20:36 PM on 16 March 2011Maize harvest to shrink under Global Warming
The 'dotted' link took me on a very convoluted trip to nowhere. -
MichaelM at 20:14 PM on 16 March 2011Maximum and minimum monthly records in global temperature databases
h pierce #35 I would suggest that you consider what we mean when we say that in the UK the average family had 2.4 children in 1964 and now has 1.9. By your reasoning and using your non voodoo statistics this is wrong since we cannot measure a 1/10 of a child. Implicit in discussions of global temperature changes is the term 'average' so when you see temperature I suggest you stop thinking of individual measurements and think of thousands. Have look at the wikipedia page on sampling. -
scaddenp at 19:48 PM on 16 March 2011CO2 lags temperature
Under "recent" times, CO2 levels have been much higher. Geological processes gradually remove CO2. When CO2 is above a certain level, you dont get a glacial cycle because its always warm enough to prevent ice build up and the feedbacks that amplify the glacial cycle. While the global forcing is very weak, the forcing at 65 is rather stronger. Land and altitude allow ice sheet build up in the NH. The 100,000 cycle IS a puzzle, but the problem (as with a lot of problems in paleoclimate) is not finding a solution but that there are more solutions than the data can constrain. Yes, there are missing pieces but the overall mechanism is understood. -
shoyemore at 19:09 PM on 16 March 2011Maximum and minimum monthly records in global temperature databases
From Peru #30, Alexandre #15 had the same problem but it went away. Try refreshing the page. Not sure what the cause is. I must be the only one using imageshack to store my charts. -
shoyemore at 19:07 PM on 16 March 2011Maximum and minimum monthly records in global temperature databases
#34 Charlie A, Figure 2 is the cusum plot, with expected centering and expected symmetry about 0. This is actually what happens 1880 to 1940s, giving rise to the suspicion that what was going on back then was natural variation. -
h pierce at 19:03 PM on 16 March 2011Maximum and minimum monthly records in global temperature databases
ATTN: Chris Thank you for your response! An organic chemist, I isolate, identify and synthesize insect pheromones, and I don't know much about or use stats. However I do make measurements and know the rules re significant figures. Chris says: There are thousands of thermometers each taking at least a couple of readings a day for decades; a few tenths of a degree difference is easily distinguishable from noise. If the resolution of the therometer is +/- 1 deg F and data is recored to the nearest whole degree, then any mean computed from that data is rounded to the last signicant figure of the measurement. This is what I have taught Chem 101 lab students for years Your claim that "a few tenths of degree difference is easily distinquishable from noise" is obtained by voo-doo statistics and nobody really believes this. If you want to _know_ temperature to +/- 0.1 deg C, you use a therometer that has that resolution and is properly calibrated. What is your opinion of my proposal for computing "weather noise"Moderator Response: You need to augment your knowledge of the rules re significant figures, with knowledge of the law of large numbers, which increases accuracy as the sample size grows. -
Bern at 18:58 PM on 16 March 2011Maize harvest to shrink under Global Warming
cloa513 @1: Your comment comes across as if you're just making stuff up, to be honest, to try and de-value this study. The bar to get a study into Nature is quite high, and if the authors had ignored such factors, it's unlikely the review process would have let the paper through. I think the point to take away is that this was a study of real-world conditions - it just so happens that the variety of climates where the crops were trialled allowed the researchers to estimate what would happen in the event of warming. I.e. how does the yield vary between an area with mean growing season temperature of X ºC, compared to one with mean temp of (X+1) ºC. I also assume that variances of rainfall etc were controlled as far as possible when making the comparison. Having said that, a 1ºC increase in global temps may significantly change rainfall patterns, so there are still plenty of caveats, I imagine! -
Riduna at 18:51 PM on 16 March 2011And so castles made of sand fall in the sea, eventually
Daniel @ 3 Thank you for reminding us that Dr Weiss study is on imp[act. Odd then that the impact on the New England States, particularly the New York/Jersey City conurbation, is not shown. In my article I showed that a 2.5m SLR would have the most dire effects, crippling NY and causing such dislocation as to make much of the city non-functionable and unliveable. Then there are the effects on cities such as Boston, Baltimore, DC. At 2.5m SLR they do not bear thinking about and if Hansen is right (he usually is), socio-economic destruction is inevitable. Further, there is no defence against SLR. No map, no discussion. Pity.Moderator Response: [DB] See the update section in the post at top. I'll have another post coming out in about a day similarly addressing other parts of the world. It will also include larger-scale renditions of sea level rise impacts on the cities you mention.Edit: Post available here.
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cloa513 at 18:37 PM on 16 March 2011Maize harvest to shrink under Global Warming
What were actual conditions the crops were growing under- average temperature is useless descriptive of conditions. So you fried it under 40C and then froze under 0C so it didn't do well. Average 20C. -
Tom Curtis at 17:43 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
PhysSci @561, I am not in general going to respond to your comments, which I consider to be little more than spam. If you want to discuss the issue, mount an argument, don't snipe, then hide behind an as yet unpublished paper. However, in this case you are clearly only partially correct. Specifically, if back radiation tends to heat the surface beyond the temperature dictated by the lapse rate, convection will increase, cooling the surface. 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. This is an important effect in temperate zones and the poles where outgoing longwave radiation is greater than incoming short wave radiation. More importantly, this effect is very well known to atmospheric physicists and is part of the full explanation of the greenhouse effect as expounded in elementary textbooks (although it does get passed over in many popular science accounts). -
Bern at 17:37 PM on 16 March 2011And so castles made of sand fall in the sea, eventually
Daniel @ 5: I guess that's another one of those tipping points - although in this case, it will be a socio-economic one, when society at large starts to fully appreciate the implications of climate change. A quick google search reveals a news article claiming Australia stands to lose at least $150 billion worth of real estate value as a result of 0.9m of rise (number supposedly sourced from the insurance industry - and they note it's not covered by insurance!). That'd pay for the replacement of a whole lotta coal-fired power stations...Moderator Response: [DB] Check out the maps of Australia I include on the next post on this subject (see next comment response for teaser info). -
Tom Curtis at 17:34 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
Climate_Protector, you indicated that with the low concentrations involved, the GHG must have a very powerful effect. They do not have a powerful effect per molecule, but a lot of molecules are involved. As to who powerful, this is a graph of the absorption of IR by CO2 travelling through 1 meter of atmosphere at sea level at the wavelengths where it is strongest as an absorber of CO2 (courtesy of Science of Doom):
And so you can see the same thing with your own eyes:
Please ignore the comment at the end of the video about "That's exactly how CO2 works in the atmosphere ..." which, as we discussed above, presents only half of the equation.
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Tom Curtis at 17:26 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
CP @552: 1) Your guess is correct. The vast majority of the GH effect is caused by CO2 and water vapour. As it happens, concentrations of water vapour fall to a level where IR radiation can escape to space in its most strongly absorbing frequencies at an altitude of about 5 km. For CO2, that altitude is about 8 km. That means the IR radiation escaping to space comes from a source about 30 degrees cooler than the surface for the frequencies where water vapour is a strong absorber of IR radiation, and about 42 degrees colder for frequencies where CO2 is a strong absorber (including in that part where it overlaps with H2O). The reason the troposphere cools with altitude is because of the rate air heats (or cools) due to compression (or expansion) as it falls (or rises) in the atmosphere. Because air is cooled as it rises by expansion, and heats as it falls through compression, this establishes a stable rate of temperature change with altitude (the lapse rate) such that, if the atmosphere lies near that rate, it will not tend to rise or fall, and if it is far from that rate, it will tend to rise or fall until it is close to it. That rate is a function of the gravitational acceleration and the specific heat capacity of the gas involved. 2) The actual enhancement is greater than 33 degrees C, but the exact amount is difficult to determine, for reasons I discussed @464 on this thread. 3)The following is a graph of the H2O concentrations in the atmosphere at 100% humidity at various temperatures:
You can see that a typical concentration would be between 0.5 and 1% (approx. 33 to 66% humidity at 15 degrees C) but it can rise much higher and go much lower. You should also note that because the concentration falls sharply with falling temperature, H2O concentrations fall sharply with altitude. That is why its effective altitude for radiation to space is lower than that for CO2. It also means CO2 is relatively speaking a far more important green house gas at the poles than at the equator (where water vapour is more dominant).
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PhysSci at 17:09 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
The key to understanding the GH effect is NOT radiative transfer ... -
PhysSci at 17:07 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
Did you know that convection can offset the potential warming by back radiation. If you try solving the radiative transfer simultaneously with convective heat exchange, you will see that convection can neutralize the entire effect of back radiation! -
PhysSci at 17:02 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
Gentlemen, absorption and re-emission can only redistribute available energy, but cannot produce extra heat in the atmosphere needed to explain the near-surface thermal enhancement presently called atmospheric 'greenhouse effect'. That why the key question is the one I asked in 558. -
Tom Curtis at 16:55 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
RW1 @553, 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. -
PhysSci at 16:53 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
Also, think about what might be contributing to the internal energy of the atmosphere (particularly the lower troposphere) besides the Sun? In other words, is there another factor that can enhance the kinetic energy of air beyond the level supported by the absorbed solar solar radiation)? -
trunkmonkey at 16:49 PM on 16 March 2011CO2 lags temperature
scaddenp, the orbital variations have probably been constant as long as there has been life on earth, yet glacial periods are exceptional in earth history.We're just lucky I guess? The orbital insolation variation is miniscule, on the order of a tenth of a Watt per square meter, and its 100000yr signal matches only rather crudely the glacial-interglacial periodicity.I sense were working a puzzle with missing pieces. -
Tom Curtis at 16:48 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
RW1 @547: "All I'm saying is an increase in CO2 concentration will increase absorption in the CO2 absorbing bands, yes, but this does not necessarily mean all of the other absorbing bands will remain constant, especially at various levels of the atmosphere where their concentrations can vary (H20 in particular). That increased CO2 will decrease total transmittance through the whole atmosphere not definite by any means - just seemingly probable." Not only probable, but observed, as shown in this plot of the differences in brightness spectra for various wavelengths between 1970 and 1996:
So, not only is your proposition extremely improbable, it is known to be false from observation.
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PhysSci at 16:40 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
What about the strength of the 'greenhouse' effect? Anybody agree that its 133C increase of surface temperature, and not 20 or 33? -
PhysSci at 16:35 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
What's important to realize here is that air temperature is a direct function of the internal energy of the atmosphere at any level, and IR emission is a product (result) of that temperature, not the other way around! So in the chain of cause and effects, the sequence is: Internal energy --> temperature --> IR radiation. -
PhysSci at 16:27 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
II see that the focus is now on the excess internal energy in the lower troposphere. Does this mean that everyone agrees that solar input alone cannot account for that additional energy? -
dana1981 at 15:53 PM on 16 March 2011Indonesian translation of The Scientific Guide to Global Warming Skepticism
That's an impressive list of languages!Response: I forgot to say, Icelandic is also on the way... -
RW1 at 15:30 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
Tom Curtis (RE: 548), "As it happens, the atmosphere radiates 37.4% (199 w/m^2/532 w/m^2) of its energy to space, and 62.6% to the surface (333 w/m^2/532 w/m^2). That means it radiates 37.4% of the energy it receives by convection to space, and 37.4% of the energy it receives by evapo/transpiration to space, and 37.4% of the energy it absorbs directly from the sun to space, and 37.4% receives as IR radiation from the surface to space. It follows also that 33% (175 w/m^2/ 531 w/m^2) of back radiation comes from energy introduced to the atmosphere other than by absorbing IR radiation from the surface." What? How can the atmosphere radiate 199 W/m^2 to space from thermals and evaporation when it only moves 97 to the atmosphere? -
Climate_Protector at 15:28 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
Tom Curtis @ 548: Yes, thank you! This explanation is much better (for my level of understanding at least)! A couple more questions, though: 1) Why does the atmosphere radiate 67% more IR energy to the surface as it does to space? My guess is because temperature decreases with height (at least in the troposphere), but then what's causing the temperature to drop with altitude? Is is the decrease in water vapor concentration? (because I think CO2 profile is pretty uniform throughout the troposphere, correct?). Bur water vapor amounts in the air depends on temperature. So what's driving what? 2) What is the actual enhancement of the surface temperature due to presence of GH gases, i.e. the greenhouse effect? This question relates to the comment in my previous posting about the amount of absorbed solar radiation in the absence of atmosphere and clouds. About GHG concentrations, I just found a number about the average H2O vapor concentration in the air - 0.25%. Does this sound right? So that means that the mean concentration of all GH gases is about 0.5% or less, correct? ... It's amazing how this minute amount is able to warm the planet to such an extend!! This means the efficiency of redirecting of IR energy towards the surface by GH gases is quite high! -
2nd law of thermodynamics contradicts greenhouse theory
Climate_Protector - Please keep in mind that the overly simplified example I gave was a Gedankenexperiment, intended to describe the important of certain aspects of the climate system if everything else is held fixed. If the Earth were at -17C, we would have a "snowball Earth", extremely high albedo from ice sheets, and the final state would be much much colder. That doesn't matter for the point of a GHG reducing effective emissivity. Suffice it to show that we would be hugely colder without it, and that energy levels can be higher at the surface than incoming values depending on how effectively the energy leaves. As to the values I gave: 100% - 80% = 20% passing through without absorption. Half the 80% (40%) radiates up as well, so upward radiation is 20%+40% = 60% of 240, or 144. The difference between incoming and outgoing is 96, so this cannot be a stable state. Given the (toy) numbers I gave, with 60% of surface going out to space, 240 / 60% * 100% = 400. That's a stable number. Again - that was an overly simplified example to demonstrate the principle. Actual calculations are done line by line modeling 50+ layers of the atmosphere, incorporate convection and latent heat, and multiple greenhouse gases with different altitude distributions such as H2O and CO2. It's the difference between a high-school physics experiment discussing spherical frictionless objects, and a numeric integration of a complex function. --- Opacity is a straight blockage of light, which may or may not result in some thermal radiation at possibly different wavelengths - Absorption/Emission are thermal radiation terms, directly related, and absorption/emission spectra are equal at thermal equilibrium. Opacity is the wrong physical term. -
2nd law of thermodynamics contradicts greenhouse theory
Tom Curtis - You are, of course, quite correct about analogies getting pushed too far. An analogy is find for explaining some aspects of a complex system in terms the listener may understand, but overextending the analogy invariably hits the limits where the analogy no longer corresponds to the complex system. Analogies are useful for explaining forward, not reasoning/disproving backwards. That can only be done in the original, complex system with all the interactions. Still, it's a bit faster to give an analogy than to attempt a first semester thermodynamics course in a blog post... -
Climate_Protector at 14:42 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
KR @ 543: Sorry, for asking these additional questions, but I'm really trying to understand this. 1) I remember reading somewhere that this 240 W m-2 planetary absorbed solar flux includes the effect of a 30% albedo. This is Earth's actual reflectivity. So, if we are talking about Earth without an atmosphere (with emissivity of 0.98) as you suggest, then isn't it more appropriate to consider a much lower albedo in our calculations, because removing the atmosphere (or even only the water vapor) means getting rid of all clouds as well? And, I think clouds were contributing well over half of the earth albedo (not quite sure). So, an Earth without an atmosphere (or without water vapor in the atmosphere) would have an albedo of say 12-15%, correct? This implies a significantly higher absorption of solar radiation, hence higher 'black-body' temperature in the absence of water vapor (or an atmosphere). How would that change your calculations? 2) I did not quite understand, why the energy emitted back to space would be only 60% of the total 240 W m-2 originally absorbed by the system? I thought, in equilibrium, the amount of absorbed solar energy must equal the amount of emitted IR radiation to space. What happens with the 96 W m-2 imbalance? Where does this energy go? Also, in 545 you say that atmospheric opacity is not the same as emissivity, and opacity would stay constant while emissivity decreased with the addition of GH gases. This really cinfuses me, because I thought that emissivity/absorptivity is a measure of opacity - higher absorptivity resulting from more GH gases would cause higher opacity to long-wave radiation. What I did not understand? -
Tom Curtis at 14:33 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
CP @535, the atmosphere does not distinguish between the sources of energy when it radiates. As it happens, the atmosphere radiates 37.4% (199 w/m^2/532 w/m^2) of its energy to space, and 62.6% to the surface (333 w/m^2/532 w/m^2). That means it radiates 37.4% of the energy it receives by convection to space, and 37.4% of the energy it receives by evapo/transpiration to space, and 37.4% of the energy it absorbs directly from the sun to space, and 37.4% receives as IR radiation from the surface to space. It follows also that 33% (175 w/m^2/ 531 w/m^2) of back radiation comes from energy introduced to the atmosphere other than by absorbing IR radiation from the surface. The reason the GH effect is attributed to intercepting IR radiation from the surface is because simplified models are used to explain the concept. It is correct, but only provides part of the more complete explanation. The complete explanation is that GHG intercept some of the IR radiation from the surface, but replace it with their own IR radiation. Because the gases are cooler than the surface at their level of effective radiation to space, the IR radiation they produce is less energetic than that which they intercepted. The difference between the energy emitted by the atmosphere to space (composed of energy drawn from a variety of sources, as per the diagram) and the the energy from the surface makes the radiation of energy to space less efficient, thus warming the surface. So, the key terms from the diagram for the greenhouse effect are: 1) The surface IR radiation intercepted by the atmosphere (356 w/m^2); and 2) The IR radiation from the atmosphere to space (199 w/m^2). The difference between these two, a reduction of IR emission to space of 157 w/m^2, represents the loss of efficiency in reradiating energy to space, which in turn results in a warmer surface. Please note that I am not disagreeing with KR (@538 & 543). He, however is using two analogies which I dislike because they are misleading if pushed, and people always push analogies. The problem with the blanket analogy is obvious. For example, your natural push of the analogy to suggest GHG reflect IR radiation is natural given the analogy, but incorrect in fact. With regard to emissivity, increasing GHG increases the emissivity of the atmosphere, but decrease the emissivity of the Earth as a whole because the atmosphere is colder than the surface so the net radiation is initially reduced. So talking about reduced emissivity of the Earth is not wrong, but is very prone to confusion. @ 537: The proportion of GHG in the atmosphere excluding water vapour is very small. The largest proportion of it is CO2 with an atmospheric concentration of approx 0.4%, with other GHG having much smaller concentrations. Water vapour on the other hand can very between around 6% (from memory) and 0.01% of the atmosphere. Crucially, water vapour concentrations at high altitudes are very low, so at those altitudes in the frequencies in which CO2 absorbs IR, CO2 is the dominant GHG. Outside those frequencies, H2O tends to dominate. -
scaddenp at 14:32 PM on 16 March 2011CO2 lags temperature
trunkmonkey, I am not sure I follow. The ice-age is driven by orbital forcings. When the forcing changing to negative, then feedbacks work the other way pulling CO2 out of atmosphere. There is no "run-away" to pre-Pleistocene atmosphere (see here for more on run away feedback). It seems to me that you are postulating an unknown in ice-age model that doesnt exist. -
RW1 at 14:28 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
KR (RE: 545), "Ah, but basic physics tells us that it does. Emissivity (not opacity) decreases as GHG's increase, widening and deepening absorption bands, the observed satellite emission spectra matching the physics predictions, temperature must increase in response for a stable state emitting as much power as comes in, QED." I don't really want to argue. All I'm saying is an increase in CO2 concentration will increase absorption in the CO2 absorbing bands, yes, but this does not necessarily mean all of the other absorbing bands will remain constant, especially at various levels of the atmosphere where their concentrations can vary (H20 in particular). That increased CO2 will decrease total transmittance through the whole atmosphere not definite by any means - just seemingly probable. -
RW1 at 14:14 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
Tom Curtis (RE: 497), "To finish, Trenberth, Khiel and Fasullo are not obfusticating by indicating some SW radiation is absorbed in the atmosphere. They are describing an indirect emperical result, and one that is more easily determined than, for example the proportion of SW light reflected from clouds, or from the surface. The method is to measure downward SWR at the Top of the Atmosphere, upward SWR at the TOA, and subtract the later from the former. You then measure downward SWR at the surface, and subtract that result from the difference; giving you the amount of SWR absorbed. (Clearly the measurements need to be made at a large number of points and times to determine a global average.) T,K, & F (2009) list a summary of such mesurements on table 2b. It is a telling indictment of your "science" that you cannot use standard definitions correctly, and have to dismiss observational results as "obfustications". Your missing the point, and that is of the 396 W/m^2 radiated from the surface, Conservation of Energy dictates that 239 W/m^2 of if has to come from the Sun because the atmosphere cannot create any energy of its own. Yes, all 239 W/m^2 does not get to the surface as direct SW, but it gets there one way or another. Ultimately, this means the remaining 157 W/m^2 of the 396 W/m^2 emitted at the surface has to come from 'back radiation' from the atmosphere. Trenberth's depiction obfuscates this, which - along with total transmittance, is the most crucial aspect of the entire greenhouse effect. The net effect of all the other components is zero. -
2nd law of thermodynamics contradicts greenhouse theory
RW1 - "You're assuming atmospheric opacity will increase and the rate at which energy can escape will decrease with rising CO2 levels. It may, but it also may not." Ah, but basic physics tells us that it does. Emissivity (not opacity) decreases as GHG's increase, widening and deepening absorption bands, the observed satellite emission spectra matching the physics predictions, temperature must increase in response for a stable state emitting as much power as comes in, QED. That's an observation, not an assumption. An unsupported statement of "...but it also may not" is not science. The level of feedbacks is another topic entirely, Climate Sensitivity. This thread is on the existence of the radiative greenhouse effect (RGE), hence the direct forcing, and the foolishness of claiming that the RGE violates thermodynamics. -
RW1 at 13:45 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
KR, "It's insulation, pure and simple. And the more insulation between a constant input and a cold sink, the hotter the final temperature of the heated object." Except the "insulation" is not made up of one substance or even a constant mix of all the individual substances. If one of the substances changes, it could trigger changes in the other substances - making the net effect very difficult to determine. You're assuming atmospheric opacity will increase and the rate at which energy can escape will decrease with rising CO2 levels. It may, but it also may not. -
2nd law of thermodynamics contradicts greenhouse theory
Climate_Protector - The atmosphere receives energy by convection, but that only moves energy from the warm ground to the cooler air. Here's a very simple example describing emissivity. First, start with the Stefan Bolzmann equation. Power radiated depends on temperature (to the 4th power) and emissivity. In order for the energy of the Earth to be stable, it must radiate as much energy as it receives. It receives 240 W/m^2 from the Sun. If there were no GHG's, the S-B equation indicates that the temperature of the Earth, with an emissivity of 0.98, would be about -17°C (256.15°K), or chilly. For toy purposes, assume the Earth has an emissivity of 1.0 (close enough to 0.98). Add an atmosphere of greenhouse gases. Assume the GHG's absorb (say) 80% of that, and re-radiate it. Half goes up, half goes down - only 60% total of the 240 W/m^2 goes to space, or 144. That's an imbalance of 96, an effective emissivity of 0.6 rather than 1.0. Energy builds up on the surface, emitting more IR. In order to emit 240 W/m^2 with an effective emissivity of 0.6, the surface must go to ( (256.15°K)^4 * 1.0 / 0.6 ) ^ 0.25 = 291°K, or over +17°C; a 34°C difference And the surface radiation will be about 240 / 0.6 = 400 W/m^2. Pretty close for off the cuff numbers and a zero dimensional model! Real numbers are a 33°C difference, 14°C surface temperature, 396 W/m^2. Greenhouse gases insulate by absorbing then re-emitting IR, sending half the energy back down, reducing effective emissivity to space. It doesn't take a lot of thermal mass, just absorbing/emitting in the IR. -
Daniel Bailey at 13:41 PM on 16 March 2011And so castles made of sand fall in the sea, eventually
@ Bern (4) Spot-on. We should be so lucky as to only experience 1 meter of SLR by 2100. Takeaway Seize every chance possible over the next few years to unload low-lying real estate near the sea. Once more robust data comes in to clarify the true scope of SLR with a more defined timeframe the market for affected properties will collapse. The Yooper -
RW1 at 13:34 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
Climate_Protector, "'d like to clarify why I thought that GH gases may also trap heat other than IR radiation: If you look at the Trenberth et al (2009) energy budget diagram (which Tom Curtis kindly linked to at 491), you'll see that the atmosphere absorbs 396-239 = 157 W m-2 of OUTGOING long-wave radiation. This flux is only 47% of the downward IR flux (333 W m-2) shown on the same diagram. So, 53% of the back radiation must be coming from other sources (solar, evapo-transpiration etc.) indicating that GH gases also trap other types of heat. Is this correct? This also makes me wonder, why the greenhouse effect is only attributed to interception of surface IR radiation, when more than 50% of the net energy input to the atmosphere comes from sources other than surface IR flux ... Is this a legitimate conclusion assuming that Trenberth's diagram is correct?" No, because all the energy emitted from (and into) the planet is radiative, which means the net effect of all the other components has to be zero. Remember also, incoming solar energy absorbed by the atmosphere and radiated down has yet to reach the surface and this energy is included in the post albedo of about 239 W/m^2. -
trunkmonkey at 13:12 PM on 16 March 2011CO2 lags temperature
SOMETHING has buffered global warming at the apex of every interglacial warm period for the last 2 million years. Otherwise we would have reverted to the so called greenhouse climates that have dominated earth history.It would be really nice to know what that SOMETHING is.The apparent lag of CO2 behind temperature for the last 800000 years may provide a clue. Temperature has led on both the rapid recoveries where CO2 positive feedback is likely and on the slower declines to ice ages where CO2 may have acted as a brake. Whatever the SOMETHING is, it prevented CO2 from taking control of climate until possibly the last few years. -
Climate_Protector at 13:11 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
Oops, I misspelled your name in my last posting. It was directed to KR @ 538 -
Bern at 13:08 PM on 16 March 2011And so castles made of sand fall in the sea, eventually
Very true, Daniel, didn't mean to imply that I thought that was the case. I think impact studies such as this are vitally important. I guess I should have just stuck to my final point: that science is increasingly saying these are likely to be the minimum impacts we see this century. -
Climate_Protector at 13:07 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
KB 538 - Thank you. I got the idea about the insulation effect of the atmosphere a while ago. I was just trying to figure out how exactly that insulation process works, and I think you gave me a clue - the analogy with the space blanket! If I remember correctly, those blankets have very low emissivity and therefore high reflectivity with respect to IR, and that's how they prevent thermal radiation from escaping and cooling the body. So, greenhouse gases must reflect thermal radiation as well, correct? But then why they say that greenhouse gases have high IR absorptivity especially water vapor. Is it that greenhouse gases have high reflectivity and high absorptivity both at the same time?. But then you mention that "the atmosphere reduces the emissivity of the planet". Do you implay that GH gases reduce the emissivity of the atmosphere, which would mean that they themselves have low emissivity. So, I guess I got confused again ... Sorry, for not being able to follow you completely. Also, from your analogy with the space blanket, does it mean that GH gases also affect (reduce) convection? That would support my earlier conclusion (suspicion) that those GH somehow trap convective heat as well. This is a very interesting discussion to me. Thank you to all for participating.Moderator Response: [DB] You couldn't pick a better place on the Interwebs for it. -
Charlie A at 12:59 PM on 16 March 2011Maximum and minimum monthly records in global temperature databases
Shoyemore, the author says at #29 "The temperatures in the mid century period were not "record", but there was a handful of second-warmest and third-warmest months, as if a warming period had been "damped" in some way." and "Fig 2 is in industrial and healthcare monitoring knows as a "Cusum" chart which is demonstrated to be the type of chart most sensitive to a process change. As you see it dates the advent of late-century warming to 1957 - earlier than any other method." Would it be possible for you to show what the Cumsum plot would look like for earlier periods, such as 1910 to 1950? It would be interesting to see how it dates the advent of warming in the first half of the 20th century. -
Charlie A at 12:51 PM on 16 March 2011Maximum and minimum monthly records in global temperature databases
An interesting analysis along this same line is to look back 10 years or 12 years and see how many of those years are records. For example, the IPCC AR4 noted that "Eleven of the last twelve years (1995–2006) rank among the 12 warmest years in the instrumental record of global surface temperature(since 1850." Below are charts that show how things would have appeared looking at the previous 10 or 12 years.
See update 13 of Congenital Climate Abnormalities
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adelady at 12:32 PM on 16 March 2011Maximum and minimum monthly records in global temperature databases
Bern, never overlook the truly dreadful agricultural practices of the time. The dustbowls of the 30s and 40s in USA, Australia and USSR were created by idiotic plough-every-chance-you-get approaches. More agricultural land was opened up - cleared and flattened to bare exposed soil - during this period. And many farmers continued with practices they'd become used to right into the late 50s and 60s. The changed advice from central agricultural authorities took a lot of time to percolate through the industry. I remember a 1960s school textbook telling me that it was necessary to plough =several= times before seeding because that promoted "capillary action" to bring water to the surface where it was needed. These practices created enormous dust clouds because the ruined, powdery soil blew away every time it was exposed to anything more than a gentle breeze. That effect was declining but not eliminated during the period you're concerned about. My suspicion is that the decline in proportion of farmers using these methods was offset by the large expanses of farmland being cleared. So the total dust produced didn't change as quickly as it might have. An agricultural historian would be a handy person to have right now. -
adelady at 12:12 PM on 16 March 20112nd law of thermodynamics contradicts greenhouse theory
cp#536 "There must be some sort of high energy storage in the atmosphere that is maintained by the absorption of heat by GH gases." Why does it need to be in the atmosphere? The ocean provides a handy, accessible, and huge, energy storage facility right next door. (I'm assuming that the question really does reflect some difficulty here.) -
2nd law of thermodynamics contradicts greenhouse theory
Climate_Protector - The greenhouse gases act as insulators by slowing radiant energy from reaching space. At any level half of the energy going into the atmosphere (including the GHG's) gets radiated up and half down (neglecting convective effects, which are relatively small). And hence not all of the IR leaves - the "insulator" slows it down, requiring a larger energy differential between the bottom and top of the atmosphere to drive 240 W/m^2 out to space. The atmosphere doesn't have to hold the energy in thermal mass (and it doesn't have much thermal mass to start with) - just re-emit it back down and prevent it from leaving. This is a lot like those shiny "space blankets" - they have almost no thermal mass, but via IR reflection and blocking convection they insulate quite well. Without GHG's the Earth could radiate all 240 W/m^2 out to space directly. If you look at just the atmospheric layer, ~240 reach space through various pathways, driven by the 17+80+396 coming up from Earth, the 78 incident on the atmosphere from the sun, minus the 333 going down as "backradiation" = 238 W/m^2 (239 without rounding, with a 0.9 calculated imbalance warming things). To make it clear, what matters is total energy entering and leaving the system, and a stable system will reach the temperatures and internal energy balances necessary for that. The atmosphere reduces the emissivity of the planet, and if emissivity reduces, temperature is the only free variable to return power outflow to the level of the incoming energy. And the stable state of the climate will move towards that point. Internal energy levels are a function of input/output and energy transfer rates, but if there's a narrow point in the energy flow (like the atmosphere) local energy levels will, must, go considerably higher to reach that throughput level. That's the first law of thermodynamics - conservation of energy, what goes in must come out. -
trunkmonkey at 12:09 PM on 16 March 2011Visualizing a History of CO2
The lowest estimates of Mesozioc CO2 I've ever seen (Breeker et al 2010)are on the order of 1000ppm. Maybe the music went to their heads a little towards the end. The truth is hard enough without embellishment. -
Daniel Bailey at 12:08 PM on 16 March 2011And so castles made of sand fall in the sea, eventually
Gentlemen: If you take a closer read of the post, you'll see that predicting the amount of SLR is not the intent of the research the post delineates. Instead, Weiss et al take published consensus estimates of expected SLR by 2100 (which admittedly do not reflect the non-linearities in ice sheet losses discussed in Hansen 2011) and factor those values into a high-rez dataset (electronic vector map) to visually demonstrate that SLR impact in the areas modeled. The idea is that, in order to most properly reflect the impact of future SLR, a picture is of greater value as a teaching tool than a table of numbers. What Weiss et al do not do is to predict by how much SLR will be, or when said SLR values will arrive. But note that the map in the post above shows 6 meter inundation areas that would be fully compliant with the potentialities discussed in Hansen 2011. An extremely valuable study in that context. Hope that helps, The Yooper -
Bern at 12:08 PM on 16 March 2011Maximum and minimum monthly records in global temperature databases
Regarding the mid-century "cooling" - can someone point me to a paper that discusses the aerosol load created by human activities in that period? Just off the top of my head, I can think of the following abnormal aerosol sources: - damaged caused by WW2, including large numbers of fires as cities / towns / industries were bombed; - increased industrial activity during WW2 (the 'War Effort' effect), possibly with decreased attention to pollution control; - increased industrial activity during the post-war period; - aerosols produced by atmospheric nuclear testing (from 1945 until the partial test ban treaty in 1963, although Wikipedia tells me the French continued atmospheric tests until 1974, the Chinese until 1980). It seems to me that those sources could (would?) have produced extremely high amounts of aerosols, some of which (particularly the nuke tests) would have been pushed into the stratosphere. If the effects of those have been quantified, is there need for any other factor to explain the mid-century cooling? The data in the post above that suggests there was no increase in cold records suggests it was mainly an impact on daytime maximum temperatures, with greenhouse gases keeping night / winter temperatures close to average, which would be consistent with aerosol effects.Moderator Response: See the Argument "It cooled mid-century," in the Advanced tabbed page.
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