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Climate Hustle

Working out climate sensitivity from satellite measurements

What the science says...

Lindzen's analysis has several flaws, such as only looking at data in the tropics. A number of independent studies using near-global satellite data find positive feedback and high climate sensitivity.

Climate Myth...

Lindzen and Choi find low climate sensitivity
Climate feedbacks are estimated from fluctuations in the outgoing radiation budget from the latest version of Earth Radiation Budget Experiment (ERBE) nonscanner data. It appears, for the entire tropics, the observed outgoing radiation fluxes increase with the increase in sea surface temperatures (SSTs). The observed behavior of radiation fluxes implies negative feedback processes associated with relatively low climate sensitivity. This is the opposite of the behavior of 11 atmospheric models forced by the same SSTs. (Lindzen 2009)

Climate sensitivity is a measure of how much our climate responds to an energy imbalance. The most common definition is the change in global temperature if the amount of atmospheric CO2 was doubled. If there were no feedbacks, climate sensitivity would be around 1°C. But we know there are a number of feedbacks, both positive and negative. So how do we determine the net feedback? An empirical solution is to observe how our climate responds to temperature change. We have satellite measurements of the radiation budget and surface measurements of temperature. Putting the two together should give us an indication of net feedback.

One paper that attempts to do this is On the determination of climate feedbacks from ERBE data (Lindzen et al 2009). It looks at sea surface temperature in the tropics (20° South to 20° North) from 1986 to 2000. Specifically, it looked at periods where the change in temperature was greater than 0.2°C, marked by red and blue colors (Figure 1).


Figure 1: Monthly sea surface temperature for 20° South to 20° North. Periods of temperature change greater than 0.2°C marked by red and blue (Lindzen et al 2009).

Lindzen et al also analysed satellite measurements of outgoing radiation over these periods. As short-term tropical sea surface temperatures are largely driven by the El Nino Southern Oscillation, the change in outward radiation offers an insight into how climate responds to changing temperature. Their analysis found that when it gets warmer, there was more outgoing radiation escaping to space. They concluded that net feedback is negative and our planet has a low climate sensitivity of about 0.5°C.

Debunked by Trenberth

However, a response to this paper, Relationships between tropical sea surface temperature and top-of-atmosphere radiation (Trenberth et al 2010) revealed a number of flaws in Lindzen's analysis. It turns out the low climate sensitivity result is heavily dependent on the choice of start and end points in the periods they analyse. Small changes in their choice of dates entirely change the result. Essentially, one could tweak the start and end points to obtain any feedback one wishes.


Figure 2: Warming (red) and cooling (blue) intervals of tropical SST (20°N – 20°S) used by Lindzen et al 2009 (solid circles) and an alternative selection proposed derived from an objective approach (open circles) (Trenberth et al 2010).

Debunked by Murphy

Another major flaw in Lindzen's analysis is that they attempt to calculate global climate sensitivity from tropical data. The tropics are not a closed system - a great deal of energy is exchanged between the tropics and subtropics. To properly calculate global climate sensitivity, global observations are required.

This is confirmed by another paper published in early May (Murphy 2010). This paper finds that small changes in the heat transport between the tropics and subtropics can swamp the tropical signal. They conclude that climate sensitivity must be calculated from global data.

Debunked by Chung

In addition, another paper reproduced the analysis from Lindzen et al 2009 and compared it to results using near-global data (Chung et al 2010). The near-global data find net positive feedback and the authors conclude that the tropical ocean is not an adequate region for determining global climate sensitivity.

Debunked by Dessler

 Dessler (2011) found a number of errors in Lindzen and Choi (2009) (slightly revised as Lindzen & Choi [2011]).  First, Lindzen and Choi's mathematical formula  to calculate the Earth's energy budget may violate the laws of thermodynamics - allowing for the impossible situation where ocean warming is able to cause ocean warming.  Secondly, Dessler finds that the heating of the climate system through ocean heat transport is approximately 20 times larger than the change in top of the atmosphere (TOA) energy flux due to cloud cover changes.  Lindzen and Choi assumed the ratio was close to 2 - an order of magnitude too small.

Thirdly, Lindzen and Choi plot a time regression of change in TOA energy flux due to cloud cover changes vs. sea surface temperature changes.  They find larger negative slopes in their regression when cloud changes happen before surface temperature changes, vs. positive slopes when temperature changes happen first, and thus conclude that clouds must be causing global warming.

However, Dessler also plots climate model results and finds that they also simulate negative time regression slopes when cloud changes lead temperature changes.  Crucially, sea surface temperatures are specified by the models.  This means that in these models, clouds respond to sea surface temperature changes, but not vice-versa.  This suggests that the lagged result first found by Lindzen and Choi is actually a result of variations in atmospheric circulation driven by changes in sea surface temperature, and contrary to Lindzen's claims, is not evidence that clouds are causing climate change, because in the models which successfully replicate the cloud-temperature lag, temperatures cannot be driven by cloud changes.

2011 Repeat

Lindzen and Choi tried to address some of the criticisms of their 2009 paper in a new version which they submitted in 2011 (LC11), after Lindzen himself went as far as to admit that their 2009 paper contained "some stupid mistakes...It was just embarrassing."  However, LC11 did not address most of the main comments and contradictory results from their 2009 paper.

Lindzen and Choi first submitted LC11 to the Proceedings of the National Academy of Sciences (PNAS) after adding some data from the Clouds and the Earth’s Radiant Energy System (CERES).

PNAS editors sent LC11 out to four reviewers, who provided comments available here.  Two of the reviewers were selected by Lindzen, and two others by the PNAS Board.  All four reviewers were unanimous that while the subject matter of the paper was of sufficient general interest to warrant publication in PNAS, the paper was not of suitable quality, and its conclusions were not justified.  Only one of the four reviewers felt that the procedures in the paper were adequately described. 

As PNAS Reviewer 1 commented,

"The paper is based on...basic untested and fundamentally flawed assumptions about global climate sensitivity"

These remaining flaws in LC11 included:

  • Assuming that that correlations observed in the tropics reflect global climate feedbacks.
  • Focusing on short-term local tropical changes which might not be representative of equilibrium climate sensitivity, because for example the albedo feedback from melting ice at the poles is obviously not reflected in the tropics.
  • Inadequately explaining methodology in the paper in sufficient detail to reproduce their analysis and results.
  • Failing to explain the many contradictory results using the same or similar data (Trenberth, Chung, Murphy, and Dessler).
  • Treating clouds as an internal initiator of climate change, as opposed to treating cloud changes solely as a climate feedback (as most climate scientists do) without any real justification for doing so. 

As a result of these fundamental problems, PNAS rejected the paper, which Lindzen and Choi subsequently got published in a rather obscure Korean journal, the Asia-Pacific Journal of Atmospheric Science. 

Wholly Debunked

A full understanding of climate requires we take into account the full body of evidence. In the case of climate sensitivity and satellite data, it requires a global dataset, not just the tropics. Stepping back to take a broader view, a single paper must also be seen in the context of the full body of peer-reviewed research. A multitude of papers looking at different periods in Earth's history independently and empirically converge on a consistent answer - climate sensitivity is around 3°C implying net positive feedback.

Last updated on 6 July 2012 by dana1981. View Archives

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Further viewing

Andrew Dessler explains in relatively simple and short terms the results from his 2011 paper:

Comments

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Comments 251 to 300 out of 483:

  1. In the absence of power from the Sun, the climate would change; therefore, by definition, power from the Sun is forcing the climate.

    Whether a particular forcing is constant or variable, doesn't make it any less of (or something other than) a forcing.
  2. Eric,

    "Regardless, as I showed in 208 the "gain" term in the paper in #150 does not use the aphelion to perihelion cycle."

    It's included in the solar input (Psun), which varies according to perihelion/aphelion. 'Psun' is the total power from the Sun and varies - it's not a constant.

    "The cyclical solar change is not considered in calculating gain."

    This isn't correct. It's automatically considered because the post albedo power is the incoming solar power minus the albedo and each varies. The gain is based on the aggregate measure of the two, which includes the increased and decreased solar power at perihelion/aphelion, as well as the changes in the albedo.

    "To put it another way, the gain is not being used to calculate earth's response to the solar change that you and I call forcing."

    Yes it is. That is in fact precisely what the gain is calculating, albeit albedo adjusted.
  3. Eric,

    The graph clearly shows the solar power fluctuting by about 20 W/m^2 from perihelion in January to aphelion in July:

    http://www.palisad.com/co2/eb/g/flux.png
  4. Ok, so the sun "forces" the climate. After albedo that "forcing" is 238 W/m^2. The "response" is 390 W/m^2. Therefore the "gain" is 1.6 Now add a permanent (hypothetical) 1 W/m^2 to the sun (forcing change by the consensus definition). What is the "response"? 391.6? Thus the temperature response is about 0.3 degrees higher according to your "gain" formula. Now, please show the evidence that a permanent 1W increase in effective solar forcing will only increase earth by only 0.3 degrees.
  5. Eric,

    At last, I think you now understand what the gain is representing, and you're asking the right question - it is the basis of the argument I've put forth.

    Before I answer the question, do we also agree that additional forcing from CO2 is the same as solar forcing? In other words, 2 W/m^2 of power from the Sun (existing or hyothetically added) is the same as 2 W/m^2 from increased CO2?
  6. Eric,

    BTW, I'm not trying to entrap you with that last question. I'm just attempting to establing that a W/m^2 of power is a W/m^2 of power, independent of where it originates from.
  7. Eric,

    I mean at least as far as intrinsic forcing is concerned.
  8. RW1 asked "2 W/m^2 of power from the Sun (existing or hyothetically added) is the same as 2 W/m^2 from increased CO2?"

    Not the same, although you didn't define "same". Existing power flux is in equilibrium at T, "gain" = 1.6. New power flux is added which causes an increase to T+delta, "gain" is much higher. That's because "gain" is not a constant as KR explained in 210.

    If instead you asked "2 W/m^2 of power from the Sun (hypothetically added) is the same as 2 W/m^2 from increased CO2?", the answer is yes.
  9. Eric,

    "Not the same, although you didn't define "same". Existing power flux is in equilibrium at T, "gain" = 1.6. New power flux is added which causes an increase to T+delta, "gain" is much higher. That's because "gain" is not a constant as KR explained in 210."

    I'm not sure what you mean here. I know the gain is not a constant. Is the "T" you're refering to temperature or something else?
  10. Eric,

    Again, I'm talking about intrinsic forcing - meaning before any potential gain or feedback (positive or negative).

    I just want to make sure we agree that each 1 W/m^2 of power from the Sun is equivalent to each 1 W/m^ of power from CO2.
  11. RW1, yes T is temperature. Each added 1 W/m^2 of power from the sun is equivalent to each added 1 W/m^2 of power from CO2. Feedback doesn't matter in the previous statement.
  12. And 1W/m2 of forcing from whatever source will induce around 0.3C of surface temperature change without considering feedbacks. However, all forcings induce feedbacks. Feedbacks are not equal however, depending on the nature of the forcing. Thus the signature for a CO2 forcing is different from the signature of a solar forcing. This is the point of several other postings.
  13. Eric,

    "New power flux is added which causes an increase to T+delta, "gain" is much higher. That's because "gain" is not a constant as KR explained in 210."

    Can you explain what you mean here? Again, I'm not sure.
  14. scaddenp,

    "However, all forcings induce feedbacks. Feedbacks are not equal however, depending on the nature of the forcing. Thus the signature for a CO2 forcing is different from the signature of a solar forcing. This is the point of several other postings.

    If this is true, then power from the Sun and power from CO2 cannot both be expressed in W/m^2 as they are.
  15. Eric,

    "Each added 1 W/m^2 of power from the sun is equivalent to each added 1 W/m^2 of power from CO2. Feedback doesn't matter in the previous statement."

    Do we also agree that power from the Sun and power from CO2 are both "forcing" the climate system?
  16. @RW1: "If this is true, then power from the Sun and power from CO2 cannot both be expressed in W/m^2 as they are."

    Sure they can. The fact they have different signatures doesn't mean they can't all be reduced to relative W/m² values.

    RW1, it's clear you have some serious issues understanding simple scientific fact. Rather than waste everyone's time here, I suggest you start taking science classes (and pay attention, this time).
  17. @RW1: "The graph clearly shows the solar power fluctuting by about 20 W/m^2 from perihelion in January to aphelion in July"

    Who cares? It's a fluctuation, as you point out yourself. The additional 4 W/m³ for a doubling of CO2 is an actual increase (and raises temperatures in both seasons).

    Seriously, go read a book or something.
  18. Eric,

    "New power flux is added which causes an increase to T+delta, "gain" is much higher. That's because "gain" is not a constant as KR explained in 210."

    The reason I ask is because I think you are saying that the gain increases as temperature and surface power increases.

    Actually, the gain decreases as radiative forcing and surface power increases. This is very clear from the graphs, where the gain is out of phase with solar input:

    http://www.palisad.com/co2/eb/g/gain.png

    This is true in both hemispheres as well:

    http://www.palisad.com/co2/eb/nh/gain.png
    http://www.palisad.com/co2/eb/sh/gain.png

    Do you see how/why this clearly illustrates negative feedback? That is as radiative forcing and power increases, the proportional amount of surface power increase is reduced, and as radiative forcing and power decreases, the proportional amount of surface power increases. This means that increases in radiative forcing and temperature are being opposed rather than reinforced by the climate system.
  19. @RW1: why do you keep citing the same website as reference? Is that your only source?

    Also, why won't you acknowledge the fact that the seasonal change represents a cycle, while CO2 forcing represents a supplementary increase, i.e. raising the "AVG" value of those irrelevant graphs?

    In short, why do you keep wasting our time? You're not going to convince anyone here with marginal theories that haven't been published and/or peer-reviewed, and which run counter to actual observations. You're also not going to convince those who are still learning the science with your convuluted, purposefully confusing arguments.

    The only people you are going to "convince" are those who have already decided they don't believe in AGW, i.e. who seek positive reinforcement of their preconcieved opinions. This begs the question, then: why are you doing this?
  20. archiesteel,

    Also, why won't you acknowledge the fact that the seasonal change represents a cycle, while CO2 forcing represents a supplementary increase...

    Because I already have acknowledged it - multiple times in this thread I might add. I'm well aware of it, and I have been long before I ever posted anything here.

    I'm trying to now take things in a step by step basis. I'm using the information from that website because it's empirically derived from satellite data and it makes the fewest assumptions about how the climate system behaves globally or hemispherically - each of which reveals critically important characteristics.

    Also, the Lindzen and Choi feedback study has been criticized as only being localized in the tropics, where as this analysis is global and gets roughly the same sensitivity.

    If you're not interested, then don't participate and continue to believe whatever you want.
  21. @RW1: I'm sorry, I wasn't clear enough. I meant to ask why, considering you agree that CO2 is an additional forcing, do you keep trying to insinuate that the CO2 effect is not significant, when the science clearly indicates it will be, and observations confirms what the science says?

    This is the crux of it: we know it is warming, and we know why it's warming. That warming is within projections that indicate an increase of about 3C (including feedbacks) for a doubling of CO2.

    So far you have failed to clearly demonstrate *anything* that challenges this, relying on a single source that has not been peer-reviewed, and which to makes some glaring mistakes (if we are to believe your interpretation - the fault may lie there instead).

    Again, please stop wasting everyone's time.
  22. archiesteel,

    Just repeating generalities doesn't make them true.

    If you don't desire to or not able to engage in genuine scientific discussion in this thread, then why participate?
  23. @RW1: "Just repeating generalities doesn't make them true."

    They're not generalities, they're the actual current level of scientific understanding on the matter of AGW.

    You have failed so far to demonstrate why we should believe in a unreviewed theory that runs counter to current science *and* observations.

    "If you don't desire to or not able to engage in genuine scientific discussion in this thread, then why participate?"

    I am both able and eager to engage in genuine scientific discussion, but apparently you're not, since you continue to latch on a dubious theory while ignoring the very thorough counter-arguments presented to you. As I said earlier, you're not really interested in learning the truth, but simply "muddy the waters", i.e. create confusion and force people to spell out obvious scientific truths in order to bog down the scientific debate.

    Hey, when even self-avowed skeptics disagree with your argument, you know you have a problem.
  24. archiesteel (RE: 273),

    You're not engaging in scientific argument - just shouting down anyone who presents any contradictory information and repeating things you've already concluded.

    If that is all you're interested in doing, then why even participate on this site - let alone this thread?
  25. @RW1: "You're not engaging in scientific argument - just shouting down anyone who presents any contradictory information and repeating things you've already concluded."

    I'm not shouting down anyone, I'm just pointing out that your arguments have all been rebutted, and yet you continue repeating them as if saying a false thing often enough would make it true.

    Unlike you, I'm more than welcome to be shown wrong about AGW. I don't *want* it to be true. However, I must conced when faced with the mountain of evidence supporting it, and the absence of evidence supporting the contrarian view.

    That's what science is about, not your purposefully-confusing attempts at minimizing the reality of AGW in order to satisfied you preconceived, politically-motivated opinions.

    "If that is all you're interested in doing, then why even participate on this site - let alone this thread?"

    Because that's not what I'm interested in doing. I'm interested in honest scientific debate, not whatever it is that you're doing.
  26. archiesteel,

    "I'm just pointing out that your arguments have all been rebutted.

    No, you're just declaring they have been successfully rebutted.

    You also keep repeating obvious things I already know, such as the increase from 2xCO2 will be in addition to (or on top of) seasonal and orbital eccentricity cycles, each of which average out and don't contribute to long term warming.

    Whatever, dude. If you're not going to specifically address anything in a way that facilitates any genuine scientific give and take discussion, I'm not going to respond anymore.
  27. @RW1: "No, you're just declaring they have been successfully rebutted."

    When someone offers a cogent counter-argument and you don't respond, then you have been successfully rebutted. I'm hardly the first one to note this here, either. Therefore, I am simply pointing out something everyone already recognizes.

    "Whatever, dude. If you're not going to specifically address anything in a way that facilitates any genuine scientific give and take discussion, I'm not going to respond anymore."

    Go ahead, "dude", it'll make my job of pointing out errors in your arguments a lot easier. :-)
  28. Re: RW1 (274, 276 et al)

    You said:
    archiesteel,

    "I'm just pointing out that your arguments have all been rebutted.

    No, you're just declaring they have been successfully rebutted.
    Thanks for clarifying that. Other than being argumentative, do you still have a purpose in continuing this conversation?

    After all, you point out that your position has been successfully rebutted.

    This site contains a plethora (lovely word, that) of science-based information substantiated by links to actual peer-reviewed sources for those interested in learning about climate science.

    Even, for example, on working out climate sensitivity from satellite information (the subject of this post the nature of which this conversation abandoned any pretense at following long ago).

    Usually I'm the one catching flack for using the appellation "dude". :)

    The Yooper
  29. archiesteel,

    When someone offers a cogent counter-argument and you don't respond, then you have been successfully rebutted. I'm hardly the first one to note this here, either.

    I know I have missed a few things and haven't responded to everything. Again, I stated that in the middle of the thread somewhere. Please point me to the specific counter-argument presented that I have failed to address and I'll respond to it.
  30. "If this is true, then power from the Sun and power from CO2 cannot both be expressed in W/m^2 as they are."

    Of course they can. The forcing term is global annual average. The energy flux (NOT power - please note that this term is normally used in context of energy transformation) produces the same temperature rise without feedbacks. See the chapter in the IPCC on why you calculate forcings in this way and evidence that it can used for arithmetic. However, for considering feedbacks, the energy flux is different spatially, temporally, and spectrally between solar and GHG (and aerosols and albedo if it comes to that).
  31. @RW1: sure, you can start by responding to chris at #222.

    I'm also curious to see if you will acknowledge you were wrong when you said: "If this is true, then power from the Sun and power from CO2 cannot both be expressed in W/m^2 as they are."

    scaddenp and I both revealed your misconceptions about what the W/m² figure means. Will you admit you were wrong about this, and thus about the 4 W/m² having to be cut in half to calculate sensitivity?

    A simple yes or no will suffice.
  32. As an off-topic note, it would be nice to be able to vote (or at least register our agreement/disagreement) on comments.

    Some sort of "real ID" registration would also help weed out sockpuppet accounts (not aiming this at anyone in particular, mind you).

    Skeptical Science 2.0, anyone? ;-)
  33. scaddenp,

    "Of course they can. The forcing term is global annual average. The energy flux (NOT power - please note that this term is normally used in context of energy transformation) produces the same temperature rise without feedbacks."

    This is what I'm referring to - the intrinsic response only. And what triggers the feedbacks? The intrinsic temperature rise - which you just said was the same for solar power and power from CO2.

    "However, for considering feedbacks, the energy flux is different spatially, temporally, and spectrally between solar and GHG (and aerosols and albedo if it comes to that)."

    Why? A watt is a watt - a joule is a joule, is it not?

    Explain to me how the surface, whose temperature is directly tied to the total power flux via Stefan-Boltzman, is going to 'know' the difference from increased power from Sun or CO2? Even further, even if it were to somehow 'know' the difference, for what physical reason would it respond differently to the same amount of heat increase?

    (*Please understand that this is not the same question as additional power from CO2 on top of all the current solar power. I think many in this thread are confusing the two, and from that, deriving that I somehow don't understand this distinction.)
  34. RW1,
    The extra power from the sun will be distributed the same as the sun's power: highest at the equator, during the summer and only increasing during the day. The power from CO2 will be distributed differently: all seasons, at night as well as day and at all latitudes. Since the forcing is distributed differently, the effect is different. This difference has been measured. The night warms more than the day, the winter has warmed more than the summer and nights have increased more than days. All this information has been discussed on this site in the last month. Most of this is discussed in the Scientific Guide to Global Warming linked on the top of this page. Give it a good read and you will know more of the background information.
  35. michael,

    "The extra power from the sun will be distributed the same as the sun's power: highest at the equator, during the summer and only increasing during the day. The power from CO2 will be distributed differently: all seasons, at night as well as day and at all latitudes. Since the forcing is distributed differently, the effect is different. This difference has been measured. The night warms more than the day, the winter has warmed more than the summer and nights have increased more than days. All this information has been discussed on this site in the last month. Most of this is discussed in the Scientific Guide to Global Warming linked on the top of this page. Give it a good read and you will know more of the background information."

    The solar forcing numbers I've used are global averages, which automatically include all of things you mention. The effect is proportionally the same, because the only source of energy in the climate system is from the Sun (plus a tiny bit of heat energy emitted from the interior of the earth). Beyond that, everything is about heat fluxes and the rate at which incoming power is delayed from leaving the planet due to the presence of GHGs and clouds in the atmosphere.
  36. #279: "the specific counter-argument presented that I have failed to address"

    Its hard to say if anyone is interested in the continuing lecture series this thread has become. The questions and counter-arguments started at comment #7, but they were evaded a number of times.

    I would ask that you refrain from suggesting to interested parties that they shouldn't participate in what you've clearly come to think of as 'your' thread. Unless you're paying the rent here, you have no say over who comes and goes.

    I suppose all I am really mildly curious about is whether the 'doubling of CO2' paper linked below the comment box here is your work as that came out with a higher sensitivity -- 1 deg C per doubling -- than you currently claim.
  37. muoncounter,

    "Its hard to say if anyone is interested in the continuing lecture series this thread has become. The questions and counter-arguments started at comment #7, but they were evaded a number of times."

    Please point to something specific you don't feel I addressed and I will respond to it (I'm serious).

    "I would ask that you refrain from suggesting to interested parties that they shouldn't participate in what you've clearly come to think of as 'your' thread. Unless you're paying the rent here, you have no say over who comes and goes."

    That's not really what I meant, but I get your point. Fair enough.

    "I suppose all I am really mildly curious about is whether the 'doubling of CO2' paper linked below the comment box here is your work as that came out with a higher sensitivity -- 1 deg C per doubling -- than you currently claim.

    No. I've never even heard of the paper or the author.
  38. RW1, in #263 you asked for an explanation of why "gain" from the website you linked to isn't constant. KR provided an explanation in #210, that temperature increases to compensate for decreasing emissivity due to GHGs. He pointed out that with no GHG, "gain" is 1.0 Q1: Do you agree or disagree with that statement?

    Your answer in #213 was "I know the gain isn't a constant, but an average. It fluctuates somewhat, but the range of fluctuation doesn't go anywhere near 8 (or 4) that is necessary to amplify 2xCO2 to 3 degrees C."

    As KR pointed out, "gain" increases with increasing GHG concentration, it does not just fluctuate in some non-specific way. Q2: Do you agree that "gain" increases with GHG concentration?
  39. (continued), Do you agree that the reason "gain" increases is because e decreases with increased CO2? Do you understand then that for "gain" as you've defined it, that 1 W/m^2 of solar forcing increase is not the same as 1 W/m^2 of equivalent CO2 forcing increase?
  40. Eric,

    "RW1, in #263 you asked for an explanation of why "gain" from the website you linked to isn't constant. KR provided an explanation in #210, that temperature increases to compensate for decreasing emissivity due to GHGs. He pointed out that with no GHG, "gain" is 1.0 Q1: Do you agree or disagree with that statement?"

    Yes, but only if there were no clouds too. In other words for the gain to be 1, there would need to be no GHGs and no clouds in the atmosphere.

    "Your answer in #213 was "I know the gain isn't a constant, but an average. It fluctuates somewhat, but the range of fluctuation doesn't go anywhere near 8 (or 4) that is necessary to amplify 2xCO2 to 3 degrees C."

    As KR pointed out, "gain" increases with increasing GHG concentration, it does not just fluctuate in some non-specific way. Q2: Do you agree that "gain" increases with GHG concentration?"


    No, not at its current operating point. The gain is simply the current ratio of surface power to post albedo solar power. Now, the surface power itself would increase with higher GHG concentration, but that's because the radiative forcing from the GHGs would also increase the power flux at the surface.

    This is why I asked if you agreed that power from the Sun was the same as power from CO2, and whether or not both are "forcing" the surface.
  41. Eric,

    "(continued), Do you agree that the reason "gain" increases is because e decreases with increased CO2? Do you understand then that for "gain" as you've defined it, that 1 W/m^2 of solar forcing increase is not the same as 1 W/m^2 of equivalent CO2 forcing increase?"

    What is "e"?
  42. When you say "not at its current operating point", that means the gain is dependent on operating point which means it increases as GHG gas concentrations increase.
  43. e is emissivity (see formula in 210)
  44. RW1 asked if I agreed that power from the Sun was the same as power from CO2, and whether or not both are "forcing" the surface.

    You've asked that over and over, please stop asking. The answer is no, those are unscientific terms. Here's a (somewhat) more scientific question: Does the (total or increase in) power from the sun have the same "gain" (as defined in the link in 150) as the (total or increase in) power from CO2? Answer: No, the paper is wrong. Explanation: reread 210, and ask questions about 210 if you don't understand it.
  45. Eric,

    Look at this way:

    At a temperature of about 288K, the surface power is about 390 W/m^2. If about 238 W/m^2 is from the Sun, then the remaining 152 W/m^2 has to come from GHGs and clouds in the atmosphere, right? So an increase in 2 W/m^2 (or 4 W/m^2) from additional CO2 (a GHG) would increase the surface power to 392 W/m^2 (or 394) because an additional 2 W/m^2 (or 4) would come from the atmosphere. The original gain is 1.638 (390/238). The new gain as a result of increased CO is 1.647 (392/238), so yes higher GHG absorption does increase the overall gain a little but not very much - only by about 0.5-1%.

    Also, if the solar power increases 2 W/m^2, the surface power also increases to 392 W/m^2 (this time 240 from the Sun; 152 from the atmosphere). The new gain is 1.633 (392/240) - only about 0.3% less than the original gain.

    So yes, there is a very small increase in the gain from increased GHG concentration, but it is no where near 8 or 4 and is still extremely close to about 1.6.

    More importantly, do you see how this shows that power from the Sun and power from CO2 is the same as far as the surface power flux is concerned? Whether the additional power is from the Sun or CO2, the net effect at the surface is proportionally the same.
  46. Eric,

    In my first example from Post 295, that's 238 from the Sun and 154 W/m^2 from the atmosphere (+2 W/m^2 from the atmosphere).
  47. The first objection to Lindzen and Choi seems to be that the full coverage, gridded data covering over 1/3 planets surface is insufficient. This criticism is somewhat ironic when all of the temperature reconstructions that show large warming start with very sparse surface measurements. These sparse measurements cover less than 1% of the total surface are and are extrapolated to 100% coverage using homogenization techniques. Similar homogenization techniques were applied to extrapolate the L&C results to cover the whole planet. Extrapolating from the equator to the poles is far more deterministic than extrapolating from the airport at a coastal city to the mountains 100's of miles away. I would suggest that you come up with a more solid 'what the science says' response to this question. If you really want to follow this logic, then everything about 'consensus' climate science is wrong for the same reason.

    Secondly, it mentions several studies that claim positive feedback. This is the result of confusion between feedback and gain. Consensus climate science assumes unit open loop gain. You can thank Hansen for starting this major FUBAR and Schlesinger for obfuscating the error behind the meaningless units of degrees K per W/m^2, which for all intents and purposes is already quantified by Stefan-Boltzmann! I should point out that from Bode, gain or in this case, sensitivity, must be dimensionless ratios of output power to intput power and only when gain is dimensionless does the very idea of quantifying feedback as positive or negative even make sense. Since the surface is warmer than it would be otherwise. The closed loop gain is clearly greater than one. Assuming unit open loop gain, a matching result can only occur when there's about 12% positive feedback. If instead of assuming unit open loop gain, we use a value of about 1.2, 12% negative feedback is required. It turns out that the 1.2 open loop gain is not arbitrary and is measurable. In this case, the system gain is the ratio between emitted surface power and total incident power and is about 1.12, compared to the surface gain of about 1.6. Albedo can't just be subtracted out when determining the system response since albedo variability is part of the control mechanism.
  48. Regarding Trentbert's mistakes, he makes several. First, he underestimates the size of the transparent window at about 18%. From line by line simulations for surface to space and surface to cloud to space radiation, weighted by cloud cover, the net transparency is closer to 22%. He completely fails to recognize that of the remaining 78%, half is radiated into space and only half back to the surface. This makes the net transmittance 22% plus half of 78% which is 61%. This means that for each W/m^2 of power that leaves the surface, 61% is radiated into space and 39% is returned to the surface. We can check this by recognizing that the gain from the surface/clouds to space is the reciprocal of the net transmittance, where 1.0/0.61 = 1.6, meaning that it takes 1.6 W/m^2 of radiated surface power for 1 W/m^2 to leave the planet. At an albedo of 0.3 and a solar constant of 341.5 W/m^2, the total power entering the system is 239 W/m^2, corresponding to 255K (from SB). The surface, at an average temperature of 287K, radiates abou 385 W/m^2, where 385/239 = 1.6. BTW, the root of all climate science evil is considering the obvious gain characteristics of atmospheric absorption as feedback, rather than as a component of the open loop gain. When properly treated as gain, the required system feedback is negative.

    Another mistake is lumping in non radiative components, for example, latent heat and thermals with radiative components. The evaporation/precipitation cycle transfers heat from the equator to the poles and as such is more like an oceanic or atmospheric circulation current, where power goes in as latent heat and comes out as wind, rain and weather. To make the math work out, he lumps in the return path for power arising from evaporated water and thermals as 'back radiation', giving a very misleading picture of the radiation budget. A far better view can be found here.

    http://www.palisad.com/co2/div2/div2.html

    Only radiative components are counted in the planets energy balance because energy can only enter and exit the planet's climate system as EM radiation. Everything else only redistributes energy within the system.
  49. RW1: "So an increase in 2 W/m^2 (or 4 W/m^2) from additional CO2 (a GHG) would increase the surface power to 392 W/m^2 (or 394) because an additional 2 W/m^2 (or 4) would come from the atmosphere."

    The 4W is TOA, so the surface power increase increases from feedback and is greater than 4W.
  50. Eric,

    "The 4W is TOA, so the surface power increase increases from feedback and is greater than 4W."

    The numbers I presented are the just intrinsic responses. After gain and potential feedback, they would be greater - but probably a little less than intrinsic + gain, because the feedback operating on the gain as a whole is appears to be negative (i.e. as the radiative forcing and surface power increases, the gain decreases and vice versa).

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