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What is the net feedback from clouds?

What the science says...

Select a level... Basic Intermediate

Evidence is building that net cloud feedback is likely positive and unlikely to be strongly negative.

Climate Myth...

Clouds provide negative feedback

"Climate models used by the International Panel on Climate Change (IPCC) assume that clouds provide a large positive feedback, greatly amplifying the small warming effect of increasing CO2 content in air. Clouds have made fools of climate modelers. A detailed analysis of cloud behavior from satellite data by Dr. Roy Spencer of the University of Alabama in Huntsville shows that clouds actually provide a strong negative feedback, the opposite of that assumed by the climate modelers. The modelers confused cause and effect, thereby getting the feedback in the wrong direction." (Ken Gregory)

The effect of clouds in a warming world is complicated. One challenge is that clouds cause both warming and cooling. Low-level clouds tend to cool by reflecting sunlight. High-level clouds tend to warm by trapping heat.

clouds

As the planet warms, clouds have a cooling effect if there are more low-level clouds or less high-level clouds.  Clouds would cause more warming if the opposite is true.  To work out the overall effect, scientists need to know which types of clouds are increasing or decreasing. 

Some climate scientists, such as Richard Lindzen and Roy Spencer, are skeptical that greenhouse gas emissions will cause dangerous warming. Their skepticism is based mainly on uncertainty related to clouds.  They believe that when it warms, low-level cloud cover increases. This would mean the Earth's overall reflectiveness would increase. This causes cooling, which would cancel out some of the warming from an increased greenhouse effect. 

However, recent evidence indicates this is not the case. Two separate studies have looked at cloud changes in the tropics and subtropics using a combination of ship-based cloud observations, satellite observations and climate models. Both found that cloud feedback in this region appears to be positive, meaning more warming.

Another study used satellite measurements of cloud cover over the entire planet to measure cloud feedback.  Although a very small negative feedback (cooling) could not be ruled out, the overall short-term global cloud feedback was probably positive (warming).  It is very unlikely that the cloud feedback will cause enough cooling to offset much of human-caused global warming.

Other studies have found that the climate models that best simulate cloud changes are the ones that find it to be a positive feedback, and thus have higher climate sensitivities.  Steven Sherwood explains one such study:

While clouds remain an uncertainty, the evidence is building that clouds will probably cause the planet to warm even further, and are very unlikely to cancel out much of human-caused global warming.  It's also important to remember that there many other feedbacks besides clouds. There is a large amount of evidence that the net feedback is positive and will amplify global warming.

Basic rebuttal written by dana1981


Update July 2015:

Here is the relevant lecture-video from Denial101x - Making Sense of Climate Science Denial

Last updated on 25 July 2017 by skeptickev. View Archives

Printable Version  |  Offline PDF Version  |  Link to this page

Comments

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Comments 101 to 150 out of 256:

  1. Sphaerica (RE: 98), "How do you get "half?" Citation, please." Trenberth actually has it being less than half - meaning more of the surface emitted energy absorbed by the atmosphere is emitted up out to space than is emitted down toward the surface (specifically, he has 157 W/m^2 emitted down and 169 W/m^2 emitted up). So using his numbers for this component would actually result in even more energy reflected away than retained. That aside, when the atmosphere (clouds or clear sky) absorbs surface emitted LW infrared, it re-emits it equally in all directions, which means the net effect through the whole atmosphere is half goes up out to space and half goes down toward the surface. Using Trenberth's numbers, he has the surface emitting 396 W/m^2. Of this, he has 70 W/m^2 passing through unabsorbed straight out to space (40 W/m^2 through the clear sky and 30 W/m^2 through the cloudy sky). 396 - 70 = 326 W/m^2 absorbed by the atmosphere. He then has 169 W/m^2 designated as being emitted up out to space, so 326 - 169 = 157 W/m^2, which is the remainder and is the amount emitted down toward the surface. 70 + 169 + 157 = 396 W/m^2 total emitted by the surface. 70 + 169 = 239 W/m^2 emitted to space. 239 coming in from the Sun + 157 emitted down from the atmosphere = 396 W/m^2 at the surface. A lot of confusion lies in Trenberth having 78 W/m^2 of the incoming energy from the Sun absorbed by the atmosphere and brought to the surface as 'back radiation'. Only it's not 'back radiation', it's 'forward radiation' yet to reach the surface that last originated from the sun - as opposed to 'back radiation' being energy that last originated from the surface. These distinctions are absolutely critical to understanding the constraints Conservation of Energy puts on the system relative to all the energy flows.
    Response: [DB] "it's 'forward radiation' yet to reach the surface that last originated from the sun" Parse:Fail
  2. RW1 - I begin to see the problem. You are not distinguishing between the current state of affairs (from the Trenberth diagram) and the feedbacks, or how those values will change with temperature changes. All of the studies show a mean estimate of slightly positive feedback for clouds, with Dessler's including a small possibility of cloud feedback being negative. Do you have any issues with the referenced papers mentioned in this thread? I do not recall seeing any such in this thread so far. If you don't, then you are not actually addressing feedback.
  3. 100, RW1,
    ...one piece of evidence among many in support of negative cloud feedback...
    Aside from your calculations (which we're still trying to work through), what other evidence do you have of negative cloud feedback?
  4. Sphaerica (RE: 93), "5. You think the reduction is so great that 1.9 isn't a problem -- it's not a dangerously high amount of warming. I have not made this claim, though I'm not sure a 1.9 C rise would be 'dangerous'. "6. You discount the fact that the lapse rate feedback might not be as great as estimated, or that CO2 and albedo feedbacks might be greater or kick in sooner than estimated, or that anthropogenic CO2 additions could actually increase with human population growth and expanding industrialization. 7. You discount the fact that other studies point to a climate sensitivity of 3+, which imply that that the cloud feedback estimates are either correct, or that any error is offset by underestimations of other positive feedbacks (or over-estimation of the lapse rate negative feedback). 8. You discount the fact that we've already seen the climate warm by 0.8˚C this century without a noticeable negative cloud feedback, i.e. that the climate is obviously sensitive enough to swing 0.8˚C in a mere 100 years (0.6˚C of that in only the last 30 years) despite your proposed fast acting negative cloud feedback." You're putting a lot of words in my mouth and making a lot of assumptions. I have not discounted anything entirely. Lots of things or combinations of things are theoretically possible. All the evidence has to be weighed very carefully. There are many lines of major contradictory evidence against net positive cloud feedback. I have presented many here, but the simplest and perhaps most significant is positive cloud feedback for GHG 'forcing' at the surface is contradictory to the system's response to solar 'forcing' at the surface. For additional GHG 'forcing' it's nearly a factor of three greater. Ultimately, for net positive cloud feedback to be supported, this has to be explained by quantifying specifically how the feedback causes this much change for the next 3.7 W/m^2 at the surface from GHG 'forcing' and why it does not for the original 98+% (239 W/m^2) incident on the surface from the Sun.
  5. 101, RW1,
    Trenberth actually has it being less than half...
    This is your interpretation, and it's incorrect, as you will see below.
    ...which means the net effect through the whole atmosphere is half goes up out to space and half goes down toward the surface.
    This is incorrect (probably because it is oversimplified).
    That aside...
    This entire paragraph is a misinterpretation of the diagram. You are reading too much into it and seeing things that are not there. 40 pass through the atmosphere (cloudy or not) directly from the surface into space. 356 are absorbed by either the clouds or the atmosphere. His diagram does not distinguish. 30 are emitted from clouds into space. You cannot say this is part of the 396 (some of it will be from thermals and evapostranspiration/latent heat, and some is the energy absorbed by the atmosphere from inbound radiation... the individual sources are not relevant, and cannot really be separated). 169 is emitted into space from the atmosphere. Again, like the 30 from clouds, you cannot separate this by source. 333 is radiated back down the surface, again from the atmosphere and clouds, without distinction. Specifically, in your calculations:
    326 - 169 = 157 W/m^2
    You can't do this, because the 169 is from the atmosphere, which is also heated by solar input, thermals and evapostranpiration/latent heat. You can't just allocate all of that to the radiation from the surface.
    157 emitted down from the atmosphere...
    No. You can't say this. 333 emitted down from the atmosphere + clouds, that's as much as you can specify.
    A lot of confusion lies in Trenberth having 78 W/m^2 of the incoming energy from the Sun absorbed by the atmosphere and brought to the surface as 'back radiation'.
    But he doesn't have that. In his diagram (which is already a simplification) it is absorbed by the atmosphere and you can't then say where it goes, any more than you can identify the molecules from a cup of water after you've dumped it into a boiling pot. The atmosphere is heated from above by the sun (78), and from below through the processes of radiation (356), thermals (17), and evapostranspiration/latent heat (80). It sheds heat by radiating upward (199, 169 atmosphere + 30 clouds) and downward (333). You cannot do from these numbers what you are trying to do, which is to allocate some measure of this specifically to clouds. Which isn't to say that it can't be done from appropriate sources, or that the information isn't available, only that your calculations here do not and can not do it.
  6. 104, RW1,
    positive cloud feedback for GHG 'forcing' at the surface is contradictory to the system's response to solar 'forcing' at the surface.
    Please explain. This makes no sense.
    For additional GHG 'forcing' it's nearly a factor of three greater.
    Please explain. This makes no sense.
    Ultimately, for net positive cloud feedback to be supported, this has to be explained by quantifying specifically how the feedback causes this much change for the next 3.7 W/m^2 at the surface from GHG 'forcing' and why it does not for the original 98+% (239 W/m^2) incident on the surface from the Sun.
    Please explain. This makes no sense to me whatsoever.
  7. Sphaerica (RE: 103), "Aside from your calculations (which we're still trying to work through), what other evidence do you have of negative cloud feedback?" I don't think you've been paying attention. I've presented much more evidence than just my initial calculations (I suggest you go back and reread the thread from the beginning), but burden of proof is on those claiming a positive cloud feedback, which subsequently leads to an enhanced warming warming of 3 C, rather than a more modest 1 C in line with the system's directly measured response to surface incident energy.
  8. 107, RW1,
    I've presented much more evidence than just my initial calculations...
    Like what? I remember nothing of the sort. I've seen nothing of any weight or importance in anything you've said so far. And no, I'm not going back to re-read the convoluted thread. If you have valid points to make, it is easy enough to state them. An unwillingness to do so speaks volumes.
    ...but burden of proof is on those claiming a positive cloud feedback...
    Huh? And why would that be? The burden of proof falls on the person trying to convince other people. I'm not trying to convince you of anything. You're trying to convince me. And so far you have a set of calculations that are invalid, logic that is insufficient, and hand waving supported by "I don't think you've been paying attention."
  9. Sphaerica (RE: 105), "This entire paragraph is a misinterpretation of the diagram. You are reading too much into it and seeing things that are not there. 40 pass through the atmosphere (cloudy or not) directly from the surface into space. 356 are absorbed by either the clouds or the atmosphere. His diagram does not distinguish." Have you read the paper? The diagram does distinguish. If you look carefully, it shows that of the 396 W/m^2 emitted at the surface, 40 W/m^2 of it passes straight through the atmosphere to space and 30 W/m^2 of the 396 is emitted through the clouds for a total transmittance of 70 W/m^2 - meaning 70 W/m^2 of the surface emitted 396 goes straight out to space without being absorbed by the atmosphere. "169 is emitted into space from the atmosphere. Again, like the 30 from clouds, you cannot separate this by source." This isn't correct because the clear sky only absorbs a total of 131 W/m^2 (0.33 x 396 = 131). If the clear sky is emitting a total of 169 W/m^2 up - that's more than the energy it absorbs, which is impossible. The 169 W/m^2 represents the total amount the atmosphere, both cloudy and clear sky, is emitting up out to space.
  10. 109, RW1,
    ...the clear sky only absorbs a total of 131 W/m^2 (0.33 x 396 = 131)...
    Where do you get this from?
    If the clear sky is emitting a total of 169 W/m^2 up - that's more than the energy it absorbs, which is impossible.
    But you can't tell how much the "clear sky" absorbs. The "clear sky" does not absorb separately from the clouds. The two are not distinct. Clouds form and dissipate very quickly. There are only three components to the ("Trenberth") system; space, atmosphere, and surface. Different components and interactions are represented in each (land/ocean at the surface, sky/clouds in the atmosphere), but you can't separate them for the purposes of Watts bookkeeping (except where he has explicitly done so). The atmosphere absorbs 78 from inbound solar radiation, 17 from thermals, 80 from evapostranspiration/latent heat, and 356 from surface radiation, for a total of 531. It radiates 169 to space from the atmosphere, 30 to space from clouds, and 333 back to the surface, for a total of 532. So the entire system gets 290 in from space, and sends 290 out to space. The atmosphere gets 531/532 in, and sends 531/532 out. The surface gets 517/516 in, and sends 516/517 back out... Each is in balance. You cannot say that the clear sky absorbs 131.
    Response: [DB] FYI, Chris Colose is explaining something along these lines to Kevin McKinney over at Open Mind as we speak type. Very understandable.
  11. RW1 - "...40 W/m^2 of it passes straight through the atmosphere to space and 30 W/m^2 of the 396 is emitted through the clouds..." No - 30 W/m^2 is emitted by the clouds, heated by radiation, convection, and latent heat. This is not a direct re-radiation or window through the clouds.
  12. RW1 - "This isn't correct because the clear sky only absorbs a total of 131 W/m^2 (0.33 x 396 = 131). If the clear sky is emitting a total of 169 W/m^2 up - that's more than the energy it absorbs, which is impossible." As Sphaerica quite clearly states, this is completely incorrect. The atmosphere receives about 532 W/m^2 from various sources, and puts out about 532 W/m^2, thus conserving energy. 131 of the input is direct solar energy. 169 of the output is IR to space. Each is just a portion of the energy flowing through the atmosphere, no impossibilities whatsoever. You are displaying a serious misunderstanding the Trenberth energy diagrams, which explains many of the (incorrect) issues you have raised.
  13. Sphaerica (RE: 110) "RW1, ...the clear sky only absorbs a total of 131 W/m^2 (0.33 x 396 = 131)... Where do you get this from?" From the ISCCP data, which says that clouds cover 2/3rds of the surface. This means 1/3rd of the surface is clear sky (i.e. cloudless). "But you can't tell how much the "clear sky" absorbs. The "clear sky" does not absorb separately from the clouds. The two are not distinct. Clouds form and dissipate very quickly." The average coverage is what matters to the energy flows. If the surface is 1/3rd clear sky, this means that 1/3 or 0.33 of the average emitted surface power passes through the clear sky. If my calculations are in error, why do they accurately predict the correct brightness temperature of 255K?
  14. Sphaerica (RE: 110) "The atmosphere absorbs 78 from inbound solar radiation, 17 from thermals, 80 from evapostranspiration/latent heat, and 356 from surface radiation, for a total of 531. It radiates 169 to space from the atmosphere, 30 to space from clouds, and 333 back to the surface, for a total of 532. So the entire system gets 290 in from space, and sends 290 out to space. The atmosphere gets 531/532 in, and sends 531/532 out. The surface gets 517/516 in, and sends 516/517 back out... Each is in balance." Show me the energy in = energy out calculations that demonstrate COE is being satisfied? There is 239 W/m^2 coming in and 239 W/m^2 leaving. The surface cannot be "getting" 517 watts in, as it's only emitting 396 W/m^2.
  15. 113, RW1,
    From the ISCCP data, which says that clouds cover 2/3rds of the surface. This means 1/3rd of the surface is clear sky (i.e. cloudless).
    No. The ability of clouds to absorb IR is different from "clear sky" (i.e. the atmosphere). One cannot simply take a percentage. It's a meaningless estimation.
    If my calculations are in error, why do they accurately predict the correct brightness temperature of 255K?
    Where do you do that, and how?
  16. 115, RW1,
    The surface cannot be "getting" 517 watts in, as it's only emitting 396 W/m^2.
    You are ignoring the 23 reflected, 17 transported through thermals and 80 transported through evapotranspiration (396 + 23 + 17 + 80 = 516).
    Show me the energy in = energy out calculations...
    Apologies... I mistyped the 290. The number is for space is 341 in and 341 out (79 reflected by clouds + 23 reflected by the surface + and 239 emitted by the atmosphere/clouds). The 239 comes from ignoring the reflected incoming radiation, which for all intents and purposes never affects the system. So 341 in - 102 reflected = 239. Similarly, 341 out - 102 reflected = 239. Everything balances.
  17. RW1, Now that we've identified the flaws in your calculations and can do away with them... 1) Do you have any actual evidence at all that cloud feedbacks would or should be negative? 2) Do you have any response to the question that I've posed 3 times (posts 27, 71, 90) and KR once (post 94)? For the fifth time, do you have any response to the fact that multiple studies, using a wide variety of methods, all point to a climate sensitivity of 3 or greater, and so the chance of cloud feedbacks being negative or neutral is slim to none?
  18. RW1 - In reference to Sphaerica's question, on cloud feedback, keep in mind that both Sphaerica and I (as in my post here) are asking about changes in cloud response from the current state, which are what will amplify or (as you seem to be arguing) damp temperature changes.
  19. 113, RW1, From the ISCCP data, which says that clouds cover 2/3rds of the surface. This means 1/3rd of the surface is clear sky (i.e. cloudless). What about cloud pressure? What about optical thickness? What about cloud albedo? How much is low cloud? How much is high cloud? What is the moisture content in the air column? What are the particulate concentrations in the air column? And there's more. Not quite so black and white is it?
  20. #92 Sphaerica at 21:57 PM on 21 April, 2011 I'd suggest that of that 341, since 78 is absorbed by the atmosphere, only 263 is available to be reflected (although this is a gross estimate, since it's more complex than that). If one assumes a cloud cover of .66 then 174 of that 263 is subject to cloud cover. 79 reflected from 174 gives .45, which is well within the ranges given by Hansen 1998 -- even at the upper end. No, that's not correct. Trenberth's figure clearly shows that according to him from the average 341 W/m2 incoming shortwave solar radiation at ToA 78 W/m2 is "Absorbed by Atmosphere" and 79 W/m2 is "Reflected by Clouds and Atmosphere" (right back to space, yes). Therefore a fraction of that 79 W/m2 is reflected by the atmosphere, not clouds, so somewhat less than 79 W/m2 remains to be reflected by global cloud cover. If cloud fraction is 0.66 as you say and no short wave radiation is reflected by the atmosphere from cloud free regions, then average cloud albedo is 79/341/0.66 (=0.35) which is way too small (should be more than 0.42). On the other hand if there is some reflection from the atmosphere in cloud free regions, average cloud albedo comes out even smaller. It may be the case that average cloud fraction projected to a plane perpendicular to incoming solar rays is much smaller than 0.66. It should be close to 0.5 to bring cloud albedo back to a reasonable range. It would simply mean cloud fraction around polar regions is much higher than the global average while it is lower above the rest of the globe. I do not know if it is the case or not, I have not seen data on average latitudinal distribution of cloud cover. If anyone knows a link to such measurements, that could help a lot. However, if cloud fraction is so high in polar regions indeed, it would diminish ice-albedo feedback tremendously, because, unlike in glacial times, there is not much ice to be melted elsewhere.
  21. 120, BP, I disagree with your logic. You cannot count the 78 absorbed by the atmosphere as eligible to be reflected. So it's not 79 of 341, it's 79 if 341-78, or 79 of 263, so it's not 79/(341*0.66)=0.35, it's 79/(263*0.66)=0.455. And, again, the 0.66 is a gross estimate. After all, what matters isn't how much of the earth's surface is under cloud cover, but how much of the daylight surface, at what angle of incidence (as you said, latitudinal distribution, as well as proximity to the day/night boundary), and what type of clouds. All in all, to me it's a total non-issue. I see no reason to doubt the numbers. Especially since, in the scheme of things, this is a bird's-eye view over-simplification diagram meant to help people better understand how energy moves through the earth's climate system, and what the term "energy budget" actually means. It's not like this is the foundation for all AOGCMs and all of climate science.
  22. Sphaerica is quite correct - the Trenberth diagrams are summaries of a great deal of data, not a climate model themselves. Which is why attempting to model cloud feedback directly and solely from the Trenberth energy 'budget' without understanding the underlying physical processes and their response to changes is rather quixotic.
  23. #122 KR at 03:55 AM on 23 April, 2011 Sphaerica is quite correct Sphaerica is not correct and you know it. It is math, not a matter of opinion.
  24. Berényi - Indeed, it's a matter of math. And physics. Tied to observations. However, Sphaerica is correct in stating that the Trenberth numbers are summaries, not a climate model, and playing with the numbers does not replicate actually considering the physical interactions of climate elements! As to the cloud effects, I suggest you look at the Trenberth 2009 paper for details. The term "cloud" occurs ~30 times in the text (not counting references to CloudSat), and in >12 bibliography titles; clouds were recognized as a major source of inter-estimate variability when that was written, and Trenberth et. al. put a lot of work into it. In other words, if you disagree with the numbers, address the paper that presented the numbers!
  25. What problems do you all have with the figure? Reflected solar radiation (101.9)/Incoming solar radiation (341.3) = 0.298 (global albedo) What is that figure doing here? I don't see you are going to get any of it as it looks pretty "constant", don't you think? No detail about low and high clouds can be got from there. Then no delta something or delta nothing, as you like. It looks quite an off-topic in this post. Just the same old song played the last few days with Trenberth being hiding behind everything because, he got mail!
  26. Sphaerica (RE: 116), "115, RW1, The surface cannot be "getting" 517 watts in, as it's only emitting 396 W/m^2. You are ignoring the 23 reflected, 17 transported through thermals and 80 transported through evapotranspiration (396 + 23 + 17 + 80 = 516)." No, I'm not ignoring them. The 23 reflected is part of the albedo and not included in the 239 W/m^2 coming in. Latent heat and thermals are kinetic and not radiative, so the net effect they have on the radiative budget is zero. All the energy entering and leaving the system is radiative. This seems to be a major source of confusion on a multitude of issues. The surface is not getting 516 watts in, as if it was, the surface would be radiating 516 instead of 396. "The 239 comes from ignoring the reflected incoming radiation, which for all intents and purposes never affects the system. So 341 in - 102 reflected = 239. Similarly, 341 out - 102 reflected = 239. Everything balances." Where is the surface emitted of 396 W/m^2 in your numbers? You have to show how the surface is receiving this many watts with 239 entering and 239 leaving. All the energy has to be accounted for, and you can't simply create an additional 120 watts out of nothing (516 - 396 = 120).
  27. Sphaerica (RE: 115), "113, RW1, 'From the ISCCP data, which says that clouds cover 2/3rds of the surface. This means 1/3rd of the surface is clear sky (i.e. cloudless).' No. The ability of clouds to absorb IR is different from "clear sky" (i.e. the atmosphere)." I know - that's the whole point of separating the clear from the cloudy sky, as I did. "One cannot simply take a percentage. It's a meaningless estimation." Relative to the whole of the energy flow from the surface to space, the percentage of clear vs. cloudy sky is what matters. " If my calculations are in error, why do they accurately predict the correct brightness temperature of 255K? Where do you do that, and how?" At the end of my post #2.
    Response: [mc] Fixed closing italics tag.
  28. 126, RW1,
    All the energy entering and leaving the system is radiative. This seems to be a major source of confusion on a multitude of issues.
    All of the energy entering/leaving from space is radiative. That does not allow you to ignore other energy transfers between the surface and atmosphere. Those are not inconsequential. It's an "energy budget," not a "radiation budget." The diagram covers the movement of energy in a three layer model (surface, atmosphere, space). The only way for energy to get in from and out to space is radiative, but that does not apply to transfers between the surface and atmosphere. All energy transfers must be accounted for. You can't simply choose to ignore some numbers. Why do you think things add up properly when they are included, and don't when they are excluded?
    Where is the surface emitted of 396 W/m^2 in your numbers?
    I gave this in post 110, but to repeat and clarify... If you want to consider the atmosphere in total, it gets 79 in from space which is reflected back (a wash). 23 are reflected through from the surface and can also be ignored (a wash), as does the 40 that passes through radiated from the surface. That leaves us with, coming from the surface, 17 from thermals, 80 from evapotranspiration/latent heat, and 356 absorbed through radiation (we've already recognize the 40 that passes through, so we don't work with the whole 396, just the remaining 356), for a total coming into the atmosphere from the surface of 17 + 80 + 356 = 453. Another 78 are absorbed from inbound sunlight, from space, giving a total absorbed by the atmosphere of 531. The atmosphere emits 333 down to the surface as radiation, and 199 (169 from the atmosphere, 30 from clouds) up into space, for a total of 532. So the atmosphere gets 531(532) from above and below, and sends out 532(531) up and down, but not in equal measure (if it did the surface of the planet would be 255˚K, and we'd all be dead, or else we'd be ice-loving lifeforms huddling around geothermal vents in the deep ocean). We can't keep going around and around with this. It's a simple diagram. Sit down with a piece of paper and add the numbers up. It's really not that hard.
  29. Sphaerica (RE: 117), "2) Do you have any response to the question that I've posed 3 times (posts 27, 71, 90) and KR once (post 94)? For the fifth time, do you have any response to the fact that multiple studies, using a wide variety of methods, all point to a climate sensitivity of 3 or greater, and so the chance of cloud feedbacks being negative or neutral is slim to none?" Look, I can only deal with one thing at a time. There are many facets to this whole thing - each of which involve a significant degree of complexity. I can eventually address those things in their appropriate threads.
  30. 126, RW1,
    At the end of my post #2.
    As before, I cannot make heads or tails of those numbers. I can see, though, that you are trying to distinguish clear and cloudy sky in your numbers, and since we have already established that that information is not available in Trenberth's diagram, I can dismiss it as inaccurate. If you'd still like to explain that set of numbers, you can try, but please be clear. What you have now is not. But to give you a generic answer to your "why do they accurately predict" query, if your numbers come to 239 at TOA (no matter how you got there) you are going to get 255K. If they come to 390-396 from the surface, you're going to get 288K-289K. That running your calculations in reverse brought you back to these numbers is no big surprise, but doesn't validate the logic behind the calculations.
  31. 126, RW1,
    Look, I can only deal with one thing at a time.
    Apologies, but you cannot one the one hand claim that there is other evidence for negative cloud feedbacks (without producing it), and on the other ignore the contrary evidence (neatly summarized and cited by SS) provided as rebuttal. But I will agree, we should continue to focus on your numbers, and your interpretation of Trenberth's diagram, as I believe that is where you will get the greatest insight into where you are mistaken. Once we get past that, we can revisit your position on the issue by considering other factors.
  32. Quick correction. At the end of post 128, I incorrectly said the temp would be 255˚K if the atmosphere radiated heat equally in both directions. The actual temperature would be 262˚K. We'd still be ice-loving creatures living in the ocean depths near geothermal vents, but we wouldn't be quite as ice-loving as I implied.
  33. RW1 - "Look, I can only deal with one thing at a time. ... I can eventually address those things in their appropriate threads. " I would like to point out that this is the "What is the net feedback from clouds" thread - that in fact is the appropriate topic here, not various interpretations of the Trenberth energy budget. Looking up the dynamic feedback numbers in the Trenberth diagram, let's see... Look! Nothing! There is no dynamic information, nothing about net feedbacks, nothing about how various elements change with temperature, in the Trenberth diagram!
  34. Sphaerica (RE: 130), "All of the energy entering/leaving from space is radiative. That does not allow you to ignore other energy transfers between the surface and atmosphere. Those are not inconsequential. It's an "energy budget," not a "radiation budget." The diagram covers the movement of energy in a three layer model (surface, atmosphere, space). The only way for energy to get in from and out to space is radiative, but that does not apply to transfers between the surface and atmosphere. All energy transfers must be accounted for. You can't simply choose to ignore some numbers." I'm not ignoring anything. Nor am I claiming the kinetic energy flows of latent heat and thermals from the surface to the atmosphere aren't part of the whole thing. They are. The problem lies in that Trenberth returns the energy from latent heat and thermals to the surface as 'back radiation' when in reality most of it returns in kinetic form through precipitation. The bottom line is it's returned to the surface in equal and opposite amounts, so relative to the radiative budget and COE, its net effect is zero. If any of the kinetic energy moved from the surface into the atmosphere gets radiated into the atmosphere and ultimately radiated out to space, the amount returned to the surface will be less than the amount that left the surface. This will cool the surface and reduce surface emitted radiation by and equal and opposite amount. Again, this seems to be a major source of confusion. In Trenberth's diagram, the latent heat and thermals of 97 are returned to the surface as 'back radiation'. The incoming solar energy of 78 'absorbed by the atmosphere' is also brought to the surface as 'back radiation'. But it's not really 'back radiation' - it's 'forward radiation' yet to reach the surface that last originated from the Sun. The point is 239 W/m^2 from the Sun gets to the surface and becomes 396 through 157 of back radiation from the atmosphere. 333 - 97 - 78 = 158 coming back from the surface emitted of 396. 239 arriving at the surface from the Sun + 157 arriving at the surface from back radiation from the atmosphere = 396 emitted at the surface. From the surface, 70 passes through the atmosphere unabsorbed out to space and 169 is emitted by the atmosphere up out to space. 70 + 169 = 239 leaving at the TOA.
  35. Sphaerica (RE: 128), "Another 78 are absorbed from inbound sunlight, from space, giving a total absorbed by the atmosphere of 531." The atmosphere cannot create any energy of its own. COE dictates this. You can't have 531 absorbed by the atmosphere when only 239 W/m^2 are coming in and the surface is only emitting 396 W/m^2.
  36. 134, RW1,
    ...when in reality most of it returns in kinetic form through precipitation...
    No, this is wrong. The kinetic energy isn't part of the equation. You're right, it's lifted up, and then falls down. What is being transported is the heat. Thermals are bodies of air that are heated by the surface, and rise. The heat doesn't fall back down through the pull of gravity. It stays in the atmosphere until it is radiated away. Evapotranspiration puts the energy into vaporizing the water. When the water condenses in the atmosphere, that energy is released -- to the surrounding atmosphere -- as latent heat. When the rain falls, it's a cool rain, having left its heat behind in the atmosphere.
    In Trenberth's diagram, the latent heat and thermals of 97 are returned to the surface as 'back radiation'.
    Okay, so if you got this, what was the "kinetic energy" bit about? But you are wrong in saying it is returned to the surface. The same goes for the energy absorbed by the atmosphere from the sun. You can't say where it goes versus other energy. The atmosphere is a big pot, and all of the energy is part of the stew. Once it's been added, you can't say "this part of the broth came from here and has to go there."
    239 arriving at the surface from the Sun + 157 arriving at the surface
    I have told you repeatedly. You are making the 157 number up. You cannot extract that with the information given. We need to stop discussing this. If you can't interpret the diagram properly, you certainly can't out think all of the climate scientists. Sit down and work this stuff out. Don't start by assuming you're smarter than everyone. Start by assuming you are the student, and there is something here you don't get. Stop trying to second guess it. Work through the numbers. Understand the diagram. If you can do that, and we can move beyond this, we can discuss negative cloud feedbacks. We've already overloaded this threat with analyzing Trenberth's diagram (for the sake of analyzing your numbers on negative cloud feedbacks) and we're getting nowhere.
  37. (RE: my 134), I wrote: The point is 239 W/m^2 from the Sun gets to the surface and becomes 396 through 157 of back radiation from the atmosphere. 333 - 97 - 78 = 158 coming back from the surface emitted of 396. This should say: The point is 239 W/m^2 from the Sun gets to the surface and becomes 396 through 157 of back radiation from the atmosphere. 333 - 97 - 78 = 158 coming back to the surface for a total of 396 (239 + 158 = 396) (Trenberth purposefully has an extra watt in there).
  38. Sphaerica (RE: my 136), "[The kinetic energy isn't part of the equation]. You're right, it's lifted up, and then falls down. What is being transported is the heat. Thermals are bodies of air that are heated by the surface, and rise. The heat doesn't fall back down through the pull of gravity. It stays in the atmosphere until it is radiated away. Evapotranspiration puts the energy into vaporizing the water. When the water condenses in the atmosphere, that energy is released -- to the surrounding atmosphere -- as latent heat. When the rain falls, it's a cool rain, having left its heat behind in the atmosphere." Thermals and latent heat are in the form of kinetic energy. They are totally separate from and in addition to the 396 emitted radiatively by the surface. I do not dispute that some of the kinetic energy moved from the surface to the atmosphere is radiated into the atmosphere and finds its way radiated out to space. Regardless of whether it's most or only a small amount (Trenberth has all of it being returned), it's net effect is still zero on the radiative budget. I think you may not understand that the surface is emitting 396 solely due to its temperature and nothing else. As a result, it cannot be receiving more energy than this.
  39. @Sphaerica RW1 has made 52 comments to this post, so far. Virtually none of that deserves a reply. He or she went on commenting virtually because you continue to reply to him/her. In my opinion it is most of all off-topic because all those additions and subtractions don't make to "feedback". I don't want to point nothing specifically because I didn't read -nor did nor will, most of the visitors- that ping-pong of some 100 of comment. I'm saying I don't want to point, but I suspect that somebody might try to get some 70W/m2 reflected upwards and some whatever, say, 40W/m2 downwards and "declare" a negative feedback from that when the feedback resides in the change of cloudiness, the type of clouds and the altitude of the clouds so those 70/40 would change maybe to 71/42 or maybe to 72/38 what provides the feedback and its sign. I'm not sure what are you two discussing, but I don't see in Trenberth's figure nor in those finger calculations the feedback that may confirm or falsify the myth subject of this post. If you stop replying I think RW1 messages will end the same way foam vanishes once shaking ceases.
    Response: [muoncounter] This is deja vu all over again; by the standards of the Lindzen and Choi thread, its just getting warmed up.
  40. Sphaerica (RE: my 136), "But you are wrong in saying it is returned to the surface. The same goes for the energy absorbed by the atmosphere from the sun. You can't say where it goes versus other energy. The atmosphere is a big pot, and all of the energy is part of the stew. Once it's been added, you can't say "this part of the broth came from here and has to go there." You can derive them with the constraints COE puts on the system. There is only one source of energy - the Sun. You can't count energy twice, which is what Trenberth does in the diagram by designating 78 being absorbed by the atmosphere and also having it part of the 333 of back radiation to the surface. The atmosphere cannot create any energy of its own - the energy either last originated from the Sun or surface emitted.
  41. Sphaerica (RE: 130), "As before, I cannot make heads or tails of those numbers. I can see, though, that you are trying to distinguish clear and cloudy sky in your numbers, and since we have already established that that information is not available in Trenberth's diagram, I can dismiss it as inaccurate." Only the cloudy vs. clear sky percentages don't come directly from Trenberth's diagram. Everything else is taken directly from the diagram, as I've explained (or tried to at least). "That running your calculations in reverse brought you back to these numbers is no big surprise, but doesn't validate the logic behind the calculations. That's true, but the point is all the calculations work out with the all 'logic' I've used, and the criticisms of the 'logic' don't work out, as I've shown. For example, it was claimed the 169 designated as being 'emitted by the atmosphere' was for the clear sky, but that doesn't work because only 131 W/m^2 is actually emitted to the clear sky. Can you find a better way to quantify the relationships in a way that results in the appropriate output power and brightness temperature of 255K?
  42. @muoncounter response to #139 Oh! I see (my Goodness). So, why not a Yogi Berra section? For instance, one of the last comments telling something like "a body that emits energy solely due to its temperature cannot be receiving more energy than that" or "if the square doesn't fit the circular hole then take a drop hammer and, smash it!".
  43. RW1, We're done. As muoncounter and Alec have pointed out, I've shown way too much patience, and you quite simply don't get it... seemingly because you refuse to. I can't help you with that. The diagram is very, very simple. It's really not all that hard to understand, and that you ever thought you had the genius to prove all of climate science wrong through your clever re-interpretation of it just astounds me. You should put less time into your clever numbers, and more time into reading up on the physics behind climate science. It would help you tremendously, and the number of misconceptions and misunderstandings you hold now seem enormous -- they're holding you back. Really, the mods should go back and delete every single post, because almost none of them relate in any way to cloud feedback, and where they do, they're tainted by your misinterpretation of Trenberth's simple energy budget diagram. Conversation ends.
  44. Sphaerica (RE: 143), "We're done. As muoncounter and Alec have pointed out, I've shown way too much patience, and you quite simply don't get it... seemingly because you refuse to. I can't help you with that. Conversation ends." Suit yourself. "Really, the mods should go back and delete every single post, because almost none of them relate in any way to cloud feedback, and where they do, they're tainted by your misinterpretation of Trenberth's simple energy budget diagram." All of the my posts are directly or indirectly related specifically to the cloud feedback issue. If anything, I was the one frequently pushing to keep the discussion on topic, while others digressed.
  45. Documentary evidence that cloud feedback is positive, courtesy of the good folks at the North Pole webcam site: Spring conditions can be cloudy at the North Pole. Clouds are produced when the North Pole experiences Spring warming and the beginning of Summer melting. Water is evaporated from the melting snow surface, forming the fog and low clouds that are seen in Spring/Summer pictures from the North Pole, such as the one on the right from June 2002. In the left image, from 5/1/02 19:06 UTC, the surface is covered by fog and low clouds. Radiation energy is trapped near the surface and thus the temperatures have increased to a very warm 27 F. -- emphasis added [source] Temperature inset at lower left shows 27F as stated.
  46. muoncounter (RE: 145), "Documentary evidence that cloud feedback is positive, courtesy of the good folks at the North Pole webcam site: Spring conditions can be cloudy at the North Pole. Clouds are produced when the North Pole experiences Spring warming and the beginning of Summer melting. Water is evaporated from the melting snow surface, forming the fog and low clouds that are seen in Spring/Summer pictures from the North Pole, such as the one on the right from June 2002. In the left image, from 5/1/02 19:06 UTC, the surface is covered by fog and low clouds. Radiation energy is trapped near the surface and thus the temperatures have increased to a very warm 27 F. -- emphasis added" It's not disputed that the cloud feedback is positive in areas that are permanently snow and ice covered, such as the North Pole. This is because the albedo of clouds is roughly the same as snow and ice, so the net effect of clouds is to warm by 'trapping' additional surface emitted energy. However, the vast majority of the Earth is not snow or ice covered, which is consistent with net negative feedback for clouds, globally. Also, when ice or snow melts from warming (CO2 induced or otherwise), the primary mechanisms that drive negative cloud feedback reassert themselves - specifically the latent heat of evaporation, which has a strong cooling effect on the surface, and the clouds above become more reflective than the surface, which also has a strong cooling effect.
  47. RW1#146: "the vast majority of the Earth is not snow or ice covered, which is consistent with net negative feedback for clouds" I don't know where you live, but in my neck of the woods, nights don't get cool when there's high humidity (which is almost always) or high clouds. But here's how an actual weatherperson puts it: Clouds are regions of a high density of saturated air, (which form cloud droplets). Clouds (especially low thick clouds) have a high ability to absorb and re-emit longwave radiation. Thus, on cloudy nights much less longwave radiation is able to escape to space. Holding in heat at night is a fingerprint of the enhanced greenhouse effect. So your thesis that clouds will always be negative feedbacks doesn't hold water.
  48. 146, RW1,
    However, the vast majority of the Earth is not snow or ice covered, which is consistent with net negative feedback for clouds, globally.
    So you say, but you offer no (substantive) support that actually proves this. You keep saying there's a net negative cloud effect, but (1) you don't prove it, and (2) as several people have pointed out, the important factor isn't the net current effect, it's the net change as a result of warming. Similarly, your logic is only so much "thought experiment" with no substantive calculations. It's easy to say things like "strong cooling effect" without backing such statements with actual numbers.
  49. muoncounter (RE: 47), "I don't know where you live, but in my neck of the woods, nights don't get cool when there's high humidity (which is almost always) or high clouds. But here's how an actual weatherperson puts it: Clouds are regions of a high density of saturated air, (which form cloud droplets). Clouds (especially low thick clouds) have a high ability to absorb and re-emit longwave radiation. Thus, on cloudy nights much less longwave radiation is able to escape to space. Holding in heat at night is a fingerprint of the enhanced greenhouse effect. So your thesis that clouds will always be negative feedbacks doesn't hold water." Yes, net effect of clouds at night is to warm (or slow heat loss). This is because clouds are better at 'trapping' outgoing surface energy than the clear sky is. Again, this is not in dispute, nor does it conflict with net negative feedback for clouds. Globally averaged data automatically includes the effects of night and day.
  50. Sphaerica (RE: 148), "You keep saying there's a net negative cloud effect, but (1) you don't prove it," I've provided much evidence and logic for net negative cloud feedback. Even Dessler says in his paper the net effect of clouds is to cool by 20 W/m^2. "(2) as several people have pointed out, the important factor isn't the net current effect, it's the net change as a result of warming." I'm aware of this, but I'm not the one making the claim that the net effect of clouds is suddenly going to switch from cooling to warming on the next few watts incident on the surface.

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