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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 & Choi 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 & Choi 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 & Choi 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 & Choi (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 & Choi (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 326 to 350 out of 387:

  1. Eric, That's fine with me, please request my email address from John Cook via the contact form so I don't have to print it out publicly." There is no reason why we can't continue to discuss this here. It is completely related to the subject, though somewhat indirectly.
  2. RW1 - The net power at the surface [sum of all incoming minus outgoing energies] according to Trenberth 2009 is (161 solar + 333 back IR) - (17 thermals + 80 latent heat + 396 IR) = ~1.0 W/m^2 Not 240 W/m^2. The gross power [sum of all energy movements as all positives] is much higher, but that's a steady state exchange with no net energy flow.
  3. #325: "what is the net energy flow at the surface? It's 396 W/m^2 (according to Trenberth's diagram)" The 396 W/m^2 is not the net surface flow, it's clearly labeled as 'surface radiation'. Has all of this been due to the fact that you still can't figure out what the numbers represent in Kiehl and Trenberth's Global Energy Flows diagram? That would suggest strongly that you've never even looked at any of the links you've been given. Where I work, we call that 'doing your homework' and it does not need to be done in public. You really should take the 'work session' you've been having off line.
  4. KR, "RW1 - The net power at the surface [sum of all incoming minus outgoing energies] according to Trenberth 2009 is (161 solar + 333 back IR) - (17 thermals + 80 latent heat + 396 IR) = ~1.0 W/m^2" Yes, and what's the power flux at the surface? If it's not 396 W/m^2 then the temperature cannot be 289K. Where do you think the 396 W/m^2 is coming from? It's been backed into from Stefan-Boltzman where "e" equals 1 at the surface (396 W/m^2 = 289K). "Not 240 W/m^2. The gross power [sum of all energy movements as all positives] is much higher, but that's a steady state exchange with no net energy flow." Is the power coming in not the same as the power leaving? If only 161 W/m^2 are from the Sun, then the power leaving cannot be the same because the atmosphere cannot create any energy of its own.
  5. muoncounter, "The 396 W/m^2 is not the net surface flow, it's clearly labeled as 'surface radiation'." Same thing. The total power at the surface is the 'surface radiation'.
  6. RW1, in the chart that you are using, from http://www.palisad.com/co2/div2/div2.html the 396 shown is IR from the surface at a temperature of 289K. Where are thermals and latent heat transfer in that chart? IOW, when the surface cools by evaporation, that cooling is in addition to black body radiation.
  7. #330: The word 'net' means sum of all input and output; surface radiation (with an up arrow) is clearly an output in this context. See #327. Do your own homework.
  8. RW1, in anticipation of a few posts with muddled terminology and "sorry I meant to say...", let me give you some choices (there are no others). 1. The 396 in your link palisad.com somehow includes surface cooling (i.e. S-B is wrong) 2. Surface cooling doesn't exist (enthalpy of evaporation does not exist) 3. Surface cooling can be placed in the atmosphere black box (because ???) and thus disregarded. Please answer with just a number, then we can move on to a new topic.
  9. RW1, The heat from the CO2 is distributed differently around the globe from the sun's heat. They are not the same. You are mistaken when you say that they are the same. According to the global averages you use, the average increase in temperature from 1 W/m2 of forcing will be the same. The spatial distribution of the increase in temperature will be different. The distribution of warming has been measured and it is due to CO2 and not the sun. If you do not understand why the distribution of energy is different you should do the background reading and not claim that others who have done their homework are wrong. When you do not understand the basics you waste everyones time arguing.
  10. @RW1: so, you refuse to acknowledge you were wrong bout the nature of the W/m² figure, and thus your earlier (seemingly abandoned) argument that the additional CO2 forcing was 2 W/m² instead of 4 (using round numbers for clarity). Yet you offered no conclusive counter-argument supporting your position. Ergo, you refuse to recognize when you're wrong, which means it is impossible to have a rational debate with you. For the record, I have been corrected quite a few times on this very web site, and have admitted I was wrong then. It's not a shameful thing to do when you're interested in finding the truth. You also never answered to chris at #222, despite his very thorough rebuttal.
  11. Eric, http://www.palisad.com/co2/div2/div2.html"RW1, in the chart that you are using, from http://www.palisad.com/co2/div2/div2.html the 396 shown is IR from the surface at a temperature of 289K." Actually, that chart is using 385 at the surface for temperature of 287K (287K = 385 W/m^2 via S-B). Where are thermals and latent heat transfer in that chart? IOW, when the surface cools by evaporation, that cooling is in addition to black body radiation. How can thermals and latent heat transfer be in addition to the black body radiation? Are you saying the surface power flux is actually 493 W/m^2? (396 + 17 + 80 = 493). From Stefan-Boltzman, a surface power of 493 W/m^2 = 305.4K, which is an average surface temperature in excess of 30 C!
  12. Michael, "RW1, The heat from the CO2 is distributed differently around the globe from the sun's heat. They are not the same. You are mistaken when you say that they are the same. According to the global averages you use, the average increase in temperature from 1 W/m2 of forcing will be the same. The spatial distribution of the increase in temperature will be different. The distribution of warming has been measured and it is due to CO2 and not the sun. If you do not understand why the distribution of energy is different you should do the background reading and not claim that others who have done their homework are wrong." Show me the calculations that demonstrate that 2xCO2 is distributed differently around the globe than average incident solar power? You apparently do not know that the increase in radiative forcing from 2xCO2 of 3.7 W/m^2 is a globally calculated average - just like power from the Sun is.
  13. BTW, I'm planning on getting to Chris's #222 and the whole issue or thermal inertia from the ocean in more detail, but I can only take one thing at a time.
  14. RW1, the wood stove at 200C next to me is outputting a decent amount of black body radiation warming myself, furniture and cats. But I can also visibly see the thermals above the stove (light refraction). I can also feel that heat rising. I also have a pot of water and kettle on the stove. As that water evaporates, the pot and kettle cool and cool the stove surface under them by conduction. All these heat transfers are additive, they all subtract heat from the stove and add it to the room (the water vapor is latent heat).
  15. @RW1: "Show me the calculations that demonstrate that 2xCO2 is distributed differently around the globe than average incident solar power?" You don't need a calculation to show that increased CO2 is distributed evenly around the globe, while solar power affects hemispheres differently depending on the season. Therefore, while both figures are averaged out to provide comparative W/m² values, in reality it's possible to differentiate the effect of the two on global climate. "You apparently do not know that the increase in radiative forcing from 2xCO2 of 3.7 W/m^2 is a globally calculated average - just like power from the Sun is." Indeed they are, but that doesn't mean we cannot differentiate between the effects of increased atmospheric CO2 and seasonal solar insolation, which you seem to be arguing from the beginning. If that is *not* what you are arguing, then can you at least sum up your argument in a concise manner, so we can clearly debate it?
  16. Eric, "RW1, the wood stove at 200C next to me is outputting a decent amount of black body radiation warming myself, furniture and cats. But I can also visibly see the thermals above the stove (light refraction). I can also feel that heat rising. I also have a pot of water and kettle on the stove. As that water evaporates, the pot and kettle cool and cool the stove surface under them by conduction. All these heat transfers are additive, they all subtract heat from the stove and add it to the room (the water vapor is latent heat). None of these examples is a system at equilibrium where power in = power out, which is what the climate system is. In the case of the water in the pot on the stove - a better analogy is a pot of water where continuous heat from the burner (on low) is keeping the water at a constant temperature (at equilibrium); where the heat from the burner is the equivalent to power coming in from the Sun and the temperature of the water is equivalent to the surface power. But you didn't answer my question, what is the power flux at the surface?
  17. RW1, KR answered it in 327 for incoming, outgoing and net. My wood stove doesn't have to be at equilibrium to show that it conducts heat to the air next to it that is in addition to BB radiation. The earth does the same thing. My question to you: does the earth conduct heat to the atmosphere or not? If yes, is that included in BB radiation or not? If yes, then why is S-B formula the same in a vacuum as in air?
  18. RW1 - I just looked (again) at the link you provided here, and this graph seems to fit the status of "not even wrong". No evaporative or thermal transfer from the surface to the atmosphere. A back-radiation value of 146 W/m^2, when a value of ~333 has been established and measured repeatedly since the 1950's. 239 W/m^2 of visible light directly to the surface, rather than the 161 W/m^2 measured value (with ~78 absorbed by clouds). 93 W/m^2 through the atmospheric window, when it's only 40. See Trenberth 2009, and a more detailed component description in the earlier Trenberth 1997, plus their (excellent) references. If your hypothesis is directly contradicted by observations (as this is on multiple counts), it's time for a new hypothesis. Reality is a harsh critic, and "should have" speculations using made-up incorrect numbers, such as those on that web site, are not science.
  19. Eric, The thermals and latent heat transfer don't matter because they aren't contributing to the overall radiation budget - they are just moving energy around "non-radiatively". I'm not saying they don't occur because they definitely do; however, the way they're transfering energy isn't from absorbtion/re-radiation like GHGs and clouds.
  20. To clarify my statements in the previous post - Science consists of reasoning from measurements, exiting theories, known physical principles, etc., and generalizing new unifying and explanatory hypotheses that can be tested. Making up numbers based upon opinions of what "should be" is not science in any way, shape, or form. But if anyone is is willing to believe in the results of such an approach, I have have some investment opportunities in a couple of phlogiston and anti-gravity devices! :)
  21. Eric, "My question to you: does the earth conduct heat to the atmosphere or not?" Yes. "If yes, is that included in BB radiation or not?" No. Thermals and latent heat transfer are non-radiative components - they are conductive and convective components.
  22. RW1, unfortunately "moving energy around non-radiatively" does matter. Since the earth is moving energy into the atmosphere via latent heat and thermals, it means that "A" in the diagram in the second link in 343 is not the only source of atmospheric heat. There is also, for example, the heat released when the evaporated water condenses. That heat is missing in that diagram. It is not the only error in that diagram.
  23. RW1 >The thermals and latent heat transfer don't matter because they aren't contributing to the overall radiation budget The radiation emitted by the atmosphere is determined by its temperature, and the temperature is determined by the input of energy, which includes thermals and latent heat transfer. You cannot reason about the energy flux of the atmosphere while ignoring a significant source of that energy. If I gave you $1000, it doesn't matter if some of it was in check form and some of it was in cash, either way you have $1000 in spending power. Energy in the atmosphere works the same way, it doesn't matter how the energy got there, all that matters is that it's there.
  24. RW1 - "Thermals and latent heat transfer are non-radiative components - they are conductive and convective components": Components which move energy to the upper troposphere, where atmospheric H2O and CO2 thin enough to radiate that energy to space. This is clearly shown in the atmospheric spectra (Figure 1 here), where the notches in the TOA outgoing spectra are from colder high atmosphere GHG's rather than the surface. Much of your discussion seems to be treating the climate thermodynamics as a two-body problem, rather than the three-body separation in Trenberth, and mixing terms between them (i.e., you still don't seem to understand the energy budget diagrams, 'net power', or dynamic thermal equilibrium). Again, errors where your input numbers do not match measurements will lead to erroneous conconclusions.
  25. Eric, "RW1, unfortunately "moving energy around non-radiatively" does matter. Since the earth is moving energy into the atmosphere via latent heat and thermals, it means that "A" in the diagram in the second link in 343 is not the only source of atmospheric heat." "A" is not the only source of atmospheric heat - it's the amount of heat absorbed and re-radiated by GHGs and clouds. Why do you think energy moved thermally and convectively into the atmosphere cannot be absorbed and re-radiated by the atmosphere? "There is also, for example, the heat released when the evaporated water condenses. That heat is missing in that diagram. How is that heat missing? All of the energy is accounted for.

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