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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 251 to 275 out of 401:

  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.

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