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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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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 351 to 375 out of 421:

  1. RW1, Hold on, are you thinking that solar radiation has to stay radiation as it travels through the system? If so, you are very much mistaken. Energy can and does change forms as it travels within the system. It can start as radiation, change into thermal energy, then into convective motion, then back into radiation, or any arbitrary combination of the above. The energy can also "bounce" back and forth between the atmosphere and surface multiple times, which is how the gross back radiation manages to be larger than the net solar input. It represents the "same" energy moving back and forth between atmosphere and surface.
  2. RW1, you are trying to partially correct that incorrect diagram and are not succeeding. "A" in that diagram is just the portion of the 385 outgoing IR absorbed by the atmosphere. It is missing the heat transfer from incoming solar (78), thermals (17), latent transfer (80).
  3. No one has yet to answer my question: If 239 W/m^2 of the total power of 396 W/m^2 at the surface isn't coming from the post albedo power from the Sun, then where is it coming from?
  4. Eric, "RW1, you are trying to partially correct that incorrect diagram and are not succeeding. "A" in that diagram is just the portion of the 385 outgoing IR absorbed by the atmosphere. It is missing the heat transfer from incoming solar (78), thermals (17), latent transfer (80)." Show me the power in = power out calculations.
  5. RW1>If 239 W/m^2 of the total power of 396 W/m^2 at the surface isn't coming from the post albedo power from the Sun, then where is it coming from? Did you read my earlier post? The 396 represents the "same" power bouncing back and forth between the surface and the atmosphere. All of that energy comes from the sun. You're trying to compare gross internal exchanges with the net input at TOA, it's apples and oranges.
  6. RW1, I want to make sure this is clear: every single Watt in Trenberth's diagram comes from the sun. You cannot differentiate between what portion is or isn't from the sun, because it is all from the sun. The reason you see numbers larger than the net solar input, is because the energy can move back and forth multiple times within the system, inflating the gross internal numbers. This is the essence of the greenhouse effect.
  7. e, "Did you read my earlier post? The 396 represents the "same" power bouncing back and forth between the surface and the atmosphere. All of that energy comes from the sun. You're trying to compare gross internal exchanges with the net input at TOA, it's apples and oranges." How do you figure? Is not 239 W/m^2 from the Sun less than 396 W/m^2 at the surface?
  8. RW1 (#353), the 396 in your post is not "total power at the surface" it is just the radiated power. It is missing the other transfers. KR showed the power equation in #327
  9. e, "I want to make sure this is clear: every single Watt in Trenberth's diagram comes from the sun. You cannot differentiate between what portion is or isn't from the sun, because it is all from the sun. The reason you see numbers larger than the net solar input, is because the energy can move back and forth multiple times within the system, inflating the gross internal numbers. This is the essence of the greenhouse effect." What's your point?
  10. RW1, I am explaining to you how the gross radiation emitted by the surface can be greater than the net input from the sun, even though there are no other sources of energy other than the sun. Did my explanation make sense or no?
  11. Eric, "RW1 (#353), the 396 in your post is not "total power at the surface" it is just the radiated power. It is missing the other transfers. KR showed the power equation in #327" No, 396 W/m^2 is the total power at the surface. The "total power" at the surface is same thing as the radiated power at the surface (so is the "power flux"). If it wasn't, the temperature could not be 289K.
  12. e, "I am explaining to you how the gross radiation emitted by the surface can be greater than the net input from the sun, even though there are no other sources of energy other than the sun." We all know this already.
  13. RW1 >396 W/m^2 is the total power at the surface ... If it wasn't, the temperature could not be 289K. No total power is total power, it includes radiation as well as convective heat transfer. Stefan-Boltzmann only applies to thermal radiation not to power in general. Thus, the temperature estimate does not change, as you are deriving it only from the radiative component of total power.
  14. "No, 396 W/m^2 is the total power at the surface. The "total power" at the surface is same thing as the radiated power at the surface (so is the "power flux"). If it wasn't, the temperature could not be 289K" RW1, that is simply incorrect. The total power flux (or heat transfer) from the surface is the radiated power plus conducted power producing thermals, plus latent transfer from evaporated cooling. As you agreed in #346, the earth conducts heat to the atmosphere. That has to be added to the radiative transfer to get the total.
  15. RW1, You asked us how power at the surface could be larger than power input from the sun, I answered your question, did you understand my explanation or not?
  16. e, "No total power is total power, it includes radiation as well as convective heat transfer. Stefan-Boltzmann only applies to thermal radiation not to power in general. Thus, the temperature estimate does not change, as you are deriving it only from the radiative component of total power." There is no distinction between "thermal radiation" and power - they are one in the same. Thermal radiation is measured in W/m^2, which is an equivalent power.
  17. e, "You asked us how power at the surface could be larger than power input from the sun, I answered your question, did you understand my explanation or not?" No, I asked how 239 W/m^2 of the surface power cannot be be from the Sun?
  18. RW1 - You make a curious statement here: "There is no distinction between "thermal radiation" and power - they are one in the same" I suppose I should now junk my car (thermal expansion power from exothermic reactions, not to mention thermal conduction to convective cooling at the radiator) and electric razor (electric power), as they cannot use energy to accomplish work??? You're wandering very far afield. Power is the net movement of energy accomplishing work. Temperature is the result of energy sitting still (present in an object as molecular motion).
  19. RW1, Ok, you're just being obtuse, and I doubt you are here for serious conversation. If you can't be bothered to look up the definition of power, then this conversation is pointless.
  20. Eric, "The total power flux (or heat transfer) from the surface is the radiated power plus conducted power producing thermals, plus latent transfer from evaporated cooling. As you agreed in #346, the earth conducts heat to the atmosphere. That has to be added to the radiative transfer to get the total." Why do you think this? The 396 W/m^2 power flux at the surface already accounts for the thermals and latent heat transfer - that is why the diagram shows them in the atmosphere away from the surface and not at the surface. If there was no conduction and convection, the surface would be warmer than it is - over 30 C (396 + 17 + 80 = 493; 493 W/m^2 = 305.4K). Does this clarify things?
  21. "The 396 W/m^2 power flux at the surface already accounts for the thermals and latent heat transfer - that is why the diagram shows them in the atmosphere away from the surface and not at the surface." So you believe that the S-B formula accounts for evaporative cooling and conduction? There are no applicable factors in the formula to account for those. It determines radiation only. Ok, archiesteel was right, (110, 120, 134, ...). The fact is, RW1, that you didn't show us your incorrect website until post 150. Lesson learned for me: read the offending website completely, determine the most basic errors, don't go on tangents, don't allow tangents, and keep my promise to stop responding.
  22. Eric, "So you believe that the S-B formula accounts for evaporative cooling and conduction?" No. "There are no applicable factors in the formula to account for those." Correct. It determines radiation only." No, the S-B formula determines the equivalent temperature at the surface from the total power at the surface (and vice versa).
  23. Eric, re 302 A is simply the radiative input from the surface to the atmosphere. The atmosphere then radiates this absorbed power up and down according to the laws of BB radiation. Is it your contention that a heated gas does not radiate as a black body? Also consider that evaporation/precipitation is a closed loop which redistributes energy from the tropics to the poles. Why is this any different than an oceanic or atmospheric circulation that does the same thing? You must keep in mind that a portion (albeit small) of the planets thermal mass is in the atmosphere and that circulation currents are what move energy around the entire thermal mass, including between the oceans and the atmosphere (actually clouds).
  24. Eric, re #208 #211 The Ps and Pc values come from the raw ISCCP data. These are converted to surface and cloud top temperatures with a lookup table implementation of SB. The ISCCP defines the surface to be an ideal BB radiator with an equivalent temperature, but since in the IR, the Earth is nearly a perfect BB radiator, this is a good approximation and SB exactly defines the relationship between radiated power and equivalent temperature. Pw is generally small, but is the power converted by the Carnot engine driving weather into the work of weather. It may actually be 0 in the steady state, where the energy driving weather nominally comes from the latent heat of evaporation. The seasonal variability of the gain has more to do with seasonally variable surface reflectivity than anything else. The 1.6 value is a yearly average, so any seasonal gain variability averages out. The bottom line is that it takes 16 W/m^2 of incremental surface power for a 3C rise in surface temperature. Of the 3.7 W/m^2 of incremental absorption from doubling CO2, 1.9 W/m^2 actually affects the surface. This requires an average amplification of over 8. While the peak at the poles can even exceed 8, the average is all that matters relative to the long term effect of doubling CO2. The only way to reconcile this discrepancy is to treat power from GHG absorption as being many times more powerful at affecting surface temperatures than power from the Sun. Obviously, I can't accept this. A view of the gain as a scatter plot is here. http://www.palisad.com/co2/gf/st_ga.png The convergence of the surface gain to 1.6 is quite clear. Some of the higher gain values at the poles are the result of accounting for power transferred from mid latitudes, which tends to push mid and lower latitude gains down. While this appears to be a criticism of L&C, from the scatter plot, the average behavior of each 2.5 degree slice of latitude (green and blue dots) shows a very consistent interpolation between the equator and the poles. Note that for display purposes only, the individual gain data points were truncated to 12.
  25. Bibliovermis, re #233 and many that followed Forcing has no implicit time over which it occurs, only a time by which the system responds, known as the time constant. http://en.wikipedia.org/wiki/Time_constant The climate is readily modeled as a first order LTI as, Pi = Po + dE/dt, where Pi is the power arriving from the Sun, Po is the power leaving the planet and E is the total energy stored in the Earth's thermal mass. When dE/dt is positive, the planet warms and when negative, it cools. Po is dependent on reflectivity and the temperature of the thermal mass and other factors dependent on E, collectively lumped into tau, thus fitting the general form of an LTI described by the above wikipedia entry as, dE/dt + 1/tau E = (1-r)Pi, where r is the reflectivity and (1-r)Pi is the forcing function f(t). This is where the definition of forcing actually comes from. In fact, GHG absorption influences the time constant and is not even properly considered forcing. Only power from the Sun can actually force the climate system, what the IPCC considers forcings simply modify the systems response. This is yet another manifestation of the confusion between gain and feedback where forcing and the response to forcing are similarly confused. The response of such a system to an immediate change is called it's impulse response and takes the form of the decaying exponential exp(-t/tau). If the forcing function is a sinusoid of the form exp(-jwt), the steady state solution (after at least 4-5 periods) is a delayed sinusoid of the form exp(-jwt)/(jw+1/tau). There's a second differential equation which relates the capacity and transfer characters of a thermal mass to dT/dt and F (also shown in the above wikipedia entry), where the flux F, is equal to dE/dt. The linear relationship between dE/dt and dT/dt is often misapplied to infer a linear relationship between 'forcing' and temperature, justifying a linear sensitivity, except that dE/dt is not the forcing, Pi is the forcing function and dE/dt is the response to that forcing. Finally, solar power is far from constant. It has latitude specific daily and seasonal variability all of which are easily represented as functions of the form exp(-jwt) and from which the time constants can be inferred by measuring the response to such stimulus. If indeed this was not relevant, there would be no differences in the climate between night and day, summer and winter or even latitude. There are also long and short term solar cycles and Milankovitch forcings affecting solar variability. It's not the average magnitude of solar radiation, but how that intersects with hemispheric and seasonal specific reflectivity.

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