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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 301 to 325 out of 448:

  1. Eric, In 300, I meant to say "but probably a little less than intrinsic + average gain,"
  2. co2isnotevil, you say "Everything else only redistributes energy within the system." But in the diagram that you linked to, there is a derived absorption, A, that redistributes energy within the system. If there's no convection or thermals to redistribute heat from the surface to the atmosphere, how can you derive A?
  3. the feedback operating on the gain as a whole is appears to be negative... In post 5 you said that "gain" of 1.6 takes into account GHG, therefore includes all feedback, so your statement above makes no sense. Also you have not explained what you don't understand in post 210.
  4. Eric, "In post 5 you said that "gain" of 1.6 takes into account GHG, therefore includes all feedback, so your statement above makes no sense. Also you have not explained what you don't understand in post 210." Sorry, I should have explained this better. The gain of about 1.6 accounts for the cumulative effect of all the individual feedbacks in the climate system - positive or negative. This is not the same as the net feedback operating on the system as a whole, which appears to be negative because the global gain decreases as radiative forcing and surface power increases.
  5. Eric, "Also you have not explained what you don't understand in post 210." What specifically in 210?
  6. global gain decreases as radiative forcing and surface power increases. That makes no sense either. The "gain" as described in the paper increases with surface temperature, as shown in 210. "Gain" is 1.0 with no GHG, it is 1.6 with cumulative GHG, thus it is larger with incrementally added GHG. I'm not going to respond any more to statements that "you should have explained better" because frankly I'm in the same boat and the more I try to correct yours, the more likely I will end up making unclear statements myself.
  7. Eric, "co2isnotevil, you say "Everything else only redistributes energy within the system." But in the diagram that you linked to, there is a derived absorption, A, that redistributes energy within the system. If there's no convection or thermals to redistribute heat from the surface to the atmosphere, how can you derive A?" I think A is derived from knowing the weighted averages of the clear and cloudy sky transparent windows of the atmosphere - i.e. how much passes through clear and cloudy sky unabsorbed. If you know the post albedo input power and the surface power, the total amount A absorbed by the atmosphere can be calculated by subtracting the post albedo power from the surface power. This is how much of the surface power is coming from the atmosphere and the difference is the total amount directed out to space. By subtracting this remaining amount from the amount of power that passes through unabsorbed, you can derive how much power absorbed by the atmosphere is directed out to space (385-239 = 146; 0.24 x 385 = 93; 385 - 93 = 292: 292 - 146 = 146; 146 + 93 = 239 leaving = 255K), which is 146 W/m^2 up and 146 W/m^2 down (exactly half up and half down).
  8. Eric, "That makes no sense either. The "gain" as described in the paper increases with surface temperature, as shown in 210. "Gain" is 1.0 with no GHG, it is 1.6 with cumulative GHG, thus it is larger with incrementally added GHG. I'm not going to respond any more to statements that "you should have explained better" because frankly I'm in the same boat and the more I try to correct yours, the more likely I will end up making unclear statements myself. " I'm sorry for not being clear. What I mean is the proportional global gain change (i.e. the decrease) is much greater than the tiny little increase in gain as a result of 2xCO2. In other words, the net gain change still decreases.
  9. If you know the post albedo input power and the surface power, the total amount A absorbed by the atmosphere can be calculated by subtracting the post albedo power from the surface power. That is wrong, but also a tangent. Read Trenberth http://journals.ametsoc.org/doi/pdf/10.1175/2008BAMS2634.1 and you will see the other sources of atmospheric heat that are not accounted for in your formula.
  10. Eric, "That is wrong, but also a tangent. Read Trenberth http://journals.ametsoc.org/doi/pdf/10.1175/2008BAMS2634.1 and you will see the other sources of atmospheric heat that are not accounted for in your formula." There is 239 W/m^2 coming in from the Sun but 385 W/m^2 at the surface. This means 146 W/m^2 of the surface power has to come from the atmosphere. Unless there is some other energy source in the system other than the Sun? I've looked at the Trenberth paper. Which part (or page) are you referring to specifically?
  11. RW1, fig 1. The 239 is power into atmosphere plus surface. The diagram that is linked in post 298 is wrong since it shows all 239 hitting the surface ignoring the 78 of incoming solar that is absorbed by the atmosphere (Trenberth fig 1). Similarly in post 298, the (385-93) / 2 is wrong because it ignores the heat transfer into the atmosphere by thermals and convection (i.e. evaporation) along with the 78 incoming absorbed in the atmosphere.
  12. Eric, "RW1, fig 1. The 239 is power into atmosphere plus surface. The diagram that is linked in post 298 is wrong since it shows all 239 hitting the surface ignoring the 78 of incoming solar that is absorbed by the atmosphere (Trenberth fig 1). Similarly in post 298, the (385-93) / 2 is wrong because it ignores the heat transfer into the atmosphere by thermals and convection (i.e. evaporation) along with the 78 incoming absorbed in the atmosphere. Where is the total power coming from at the surface if not from the combined sources of the Sun and the atmosphere? If the power at the surface is 385 W/m^2 and the incoming power from the Sun is 239 W/m^2, how can the remaining 146 W/m^2 not be the amount coming from the atmosphere? If it's not the atmosphere, where is the power coming from? If 239 W/m^2 is the post albedo power entering and the power leaving, how can less than 239 W/m^2 of the surface power come from the Sun? Where is the extra energy coming from? I assume you know that the law of conservation of energy dictates that atmosphere cannot create any energy of its own - all it can do is redirect it and slow its release out to space.
  13. Eric, Show us the power in = power out calculations that demonstrate what you're talking about.
  14. Eric, In the Trenberth diagram, 161 W/m^2 is the designated amount of power from the sun at the surface. The surface power is 396 W/m^2. 396 W/m^2 - 161 W/m^2 = 235 W/m^2 (from the atmosphere). 396 W/m^2 - 70 W/m^2 (through transparent window) = 326 W/m^2. 326 W/m^2 - 235 W/m^2 = 91 W/m^2 (total directed up out to space by the atmosphere). 91 W/m^2 + 70 W/m^2 = 161 W/m^2 leaving (239 W/m^2 needed). Do you see how this shows that for power in = power out, 239 W/m^2 of the surface power has to come from the Sun?
  15. In #314, 326 W/m^2 is the total power absorbed by the atmosphere. I mean to specify that.
  16. Eric, Trenberth is showing 169 W/m^2 being emitted by the atmosphere out to space and 70 W/m^2 through the transparent window for a total of 239 W/m^2. Where is he getting 169 W/m^2 from?
  17. Eric, I think he's getting 169 W/m^2 by adding the 78 W/m^2 of power from the Sun absorbed by the atmosphere. 91 + 78 = 169. But that 78 W/m^2 is from the Sun. 78 W/m^2 + 161 W/m^2 = 239 W/m^2 from the Sun. Do you see how this shows that 239 W/m^2 of power at the surface has to come from the Sun?
  18. I think I now see where the confusion is coming from. 396 W/m^2 - 161 W/m^2 = 235 W/m^2. This means, according to the diagram, 235 W/m^2 of the power at the surface comes from the atmosphere, but 78 W/m^2 of the power from the atmosphere is from the Sun. So really only 157 W/m^2 is coming from the atmosphere (235 - 78 = 157) and 239 W/m^2 at the surface power is coming from the Sun (239 + 157 = 396 W/m^2). What a mess!
  19. RW1, we are so far off the original topic of climate sensitivity from satellite measures that it's not even remotely funny. As to the science: The information I linked in this post concerns the actual physics of thermal radiation. It's extremely clear you have not read that link, and do not understand the Stephen-Boltzmann equation. About 240 W/m^2 power arrives from the sun, ~239 W/m^2 leave, with ~0.9 W/m^2 imbalance. That's the Earth system from space. The 396+80+17 leaving the surface (into the atmosphere and space) and the 333 back-radiation are aspects of the temperatures of the surface and atmosphere that are required to radiate 239 W/m^2 to space as thermal radiation according to the Stephen-Bolzmann relationship! Your 'gain' is not a constant, not an input, but a result of thermodynamics and radiative physics. And your reliance on lumping all of that into a non-constant number (based, apparently, on a single website with non-reviewed opinions), rather than using the actual physics, has led you into what appears to me to be a web of extremely confusing statements, including your incorrect posts on "halving" TOA forcings, huge mis-scaling of CO2 forcings, claims of negative feedbacks, etc. Back on the topic of climate sensitivities - I would recommend you read the Climate sensitivity is low rebuttal, read a few of those papers, and learn about the actual physics involved. At this point, however, you haven't said anything new (or, in my opinion) correct in this thread for several hundred exchanges, and I will not be continuing my posts on the thread unless that changes.
  20. KR, "As to the science: The information I linked in this post concerns the actual physics of thermal radiation. It's extremely clear you have not read that link, and do not understand the Stephen-Boltzmann equation." I'm well aware of the physics of thermal radiation and that equation. The surface of the earth is considered to be very close to a perfect black body radiator, so an emissivity of 1 can be used (no value for "e" is required because e = 1). "About 240 W/m^2 power arrives from the sun, ~239 W/m^2 leave, with ~0.9 W/m^2 imbalance. That's the Earth system from space." If there is warming occurring, yes. "The 396+80+17 leaving the surface (into the atmosphere and space) and the 333 back-radiation are aspects of the temperatures of the surface and atmosphere that are required to radiate 239 W/m^2 to space as thermal radiation according to the Stephen-Bolzmann relationship!" This still doesn't change the fact that for power in = power out, 239 W/m^2 of the power at the surface has to come from the Sun, which means the back radiation can't be 333 W/m^2. Again, if you're claiming I'm wrong, show me the power in = power out calculations that demonstrate it (239 W/m^2 in and out). "Your 'gain' is not a constant, not an input, but a result of thermodynamics and radiative physics. And your reliance on lumping all of that into a non-constant number (based, apparently, on a single website with non-reviewed opinions), rather than using the actual physics, has led you into what appears to me to be a web of extremely confusing statements, including your incorrect posts on "halving" TOA forcings, huge mis-scaling of CO2 forcings, claims of negative feedbacks, etc." The gain is simply the ratio of surface power to post albedo solar power. The physics of surface power emission and temperature are dictated by Stefan-Boltzman, as mentioned above. I never claimed the gain is a constant - I know it varies and have stated so. I've been using the gain mainly as an average general response of the system to radiative forcing. "Back on the topic of climate sensitivities - I would recommend you read the Climate sensitivity is low rebuttal, read a few of those papers, and learn about the actual physics involved. I'll take a look at them, but I think you may be confused because you're not equating power with temperature via Stefan-Boltzman.
  21. @RW1, Eric, I suggest you exchange e-mails and take this offline, that discussion seems to be getting nowhere. In fact, the useless (and increasingly off-topic) back-and-forth seems to be only designed to waste space. RW1, why didn't you respond to my earlier request, which I made at your invitation? If you wanted to give anyone the impression that you were afraid to reply, it was a resounding success. *Nothing* you have written makes a solid case for sensitivity (with feedbacks) being lower than 3C. Why even keep up this charade?
  22. RW1 - You stated that "239 W/m^2 of the power at the surface has to come from the Sun, which means the back radiation can't be 333 W/m^2". Thank you, that indeed clarifies your position. I suggest you then take the discussion to the appropriate thread, The greenhouse effect and the 2nd law of thermodynamics, where backradiation is clearly discussed. You are conflating power (energy going somewhere, doing work) with the energy involved in the Earth's temperature. Power comes in from the sun, power goes out to space, but the internal temperature of the Earth and atmosphere is determined by the temperature required by dynamic equilibrium between these two numbers, based upon the thermal and emissive properties of surface and atmosphere, and not just a scalar value of the input/output power as you have claimed. Power involves net energy flow - the internal interchange between atmosphere, ground, and space has a net energy flow of ~240 W/m^2; the internal dynamics and interchanges are related, but not directly, nor in a scalar fashion. And, as archiesteel noted, you have made no solid case for low climate sensitivity.
  23. archiesteel, "A simple yes or no will suffice." No.
  24. 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.
  25. KR, "RW1 - You stated that "239 W/m^2 of the power at the surface has to come from the Sun, which means the back radiation can't be 333 W/m^2". Thank you, that indeed clarifies your position." What I meant was 333 W/m^2 can't be coming from the atmosphere, which Trenberth vaguely designates as "back radiation". "Power involves net energy flow - the internal interchange between atmosphere, ground, and space has a net energy flow of ~240 W/m^2; the internal dynamics and interchanges are related, but not directly, nor in a scalar fashion." And what is the net energy flow at the surface? It's 396 W/m^2 (according to Trenberth's diagram). Power equivalent temperature at the surface is calculated via Stefan-Boltzman. We can argue all you want about what the energy flows may or may not be, but this doesn't change the power flux at the surface, which is what the gain is derived from. "I suggest you then take the discussion to the appropriate thread, The greenhouse effect and the 2nd law of thermodynamics, where backradiation is clearly discussed. You are conflating power (energy going somewhere, doing work) with the energy involved in the Earth's temperature." No I'm not. All I'm doing is converting surface power to temperature via Stefan-Boltzman. "Power comes in from the sun, power goes out to space, but the internal temperature of the Earth and atmosphere is determined by the temperature required by dynamic equilibrium between these two numbers, based upon the thermal and emissive properties of surface and atmosphere, and not just a scalar value of the input/output power as you have claimed." The grey body components I think you may be referring to don't matter for the purposes of gain, because the gain is based on surface power emission and the surface is considered to be very close to perfect black body radiator where "e" equals 1.

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