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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 26 to 50 out of 95:

  1. muoncounter (RE: Post 24), You can't assume all the increase in temperature we've seen is from additional CO2. The climate doesn't do anything but change. There are many natural forces at work, the bulk of which we don't even know.
  2. @RW1: sure we can assume the warming is due to CO2, because there are no other causes that could be indentified. Of course, this means filtering out cyclical patterns, which is what climate scientists do. That said, if you want to chase for those elusive other causes, please do, and come back to us when you have actual evidence. In the meantime, we'll stick with the actual science.
  3. archiesteel (RE: Posts 27 & 28), The burden of proof is not on the skeptics to demonstrate what caused the warming because the amount and rate of warming we've experienced is well within the range of natural variability. The burden of proof is on the AGW proponents to demonstrate it was caused by CO2, and all of that evidence has to be in accordance with all other existing evidence. There can't be any significant discrepancies or inconsistencies, especially those which cannot be adequately explained in the overall context of the theory. It only takes one piece of contradictory evidence to disprove a hypothesis - no matter how much confirming evidence may exist. Now I know that climate is not an exact science, so there is some leeway; however, these basic fundamental scientific principles still apply. *And no - I'm not damorbel (whoever that is).
  4. #29: "It only takes one piece of contradictory evidence to disprove ... " Where is this piece of evidence? Love to see it. Let's review what we have seen: Begin with this quixotic statement: "... average global temperatures are actually colder at perihelion in January then at aphelion in July." Follow with some back-of-the-envelope-style calculations which some here have already called into question. Continue with the declarative judgment "response time is a non issue". Avoid all attempts to consider other SkS pages wherein these claims, many of which have been raised before, are addressed in detail. When asked for a reference, refer only to a website which concludes with the polemical ... CO2 mitigation will have no effect, other than to drag down the worlds economy and impede the goal of energy independence. A world economy, I might add (with a short veer off-topic), that was (and remains) perfectly capable of dragging itself down without any CO2 mitigation. And in rebuttal, present "... natural forces at work, the bulk of which we don't even know." No, sir, that's not evidence. And in this particular part of the blog-science world, this statement is indeed true: "basic fundamental scientific principles still apply."
  5. @RW1: "The burden of proof is not on the skeptics to demonstrate what caused the warming because the amount and rate of warming we've experienced is well within the range of natural variability." Wrong. The burden of proof *is* on the skeptics to prove that similar temperature increases have happened at this rate in the past, and that similar natural forces are at play today. There is no evidence of this, nor have you provided any. "The burden of proof is on the AGW proponents to demonstrate it was caused by CO2, and all of that evidence has to be in accordance with all other existing evidence." Wrong again. The burden of proof is on the AGW proponents to demonstrate it was caused by CO2, and all of that evidence has to be in accordance with all other existing evidence. The evidence is already there supporting AGW, if only in the satellite-measured OLR or ground-measured downward LR. In other words, all lines of evidence point to the warming being caused by CO2, while there is virtually no evidence supporting your position. "It only takes one piece of contradictory evidence to disprove a hypothesis - no matter how much confirming evidence may exist." As muoncounter said, please provide this evidence. After all, the burden of proof is on you, not on AGW proponents. AGW is the currently accepted science. The burden of proof is on the challengers.
  6. muoncounter (RE: Post 30), The biggest piece of contradictory evidence is that the amount of expected warming is absent. Due to the logarithmic response of CO2, an increase from 280 ppm to 380 ppm equals about 75-80% of the forcing from a doubling of CO2. 75% of 3 degrees C is 2.25 degrees C. During the period from about 1900-2000, the amount of warming was only about 0.6 C - less than 1/3rd of the predicted amount, and that's only if you assume all the warming was from CO2 (highly unlikely). They have tried, after the fact, to ascribe the lack of warming to be due to aerosols. Or is it ocean thermal inertia? Or something different tomorrow or next week? It seems anything but conclude the hypothesis is probably wrong, and the sensitivity is far smaller than they are still claiming it is. The scientific method dictates modifying or discarding a hypothesis when it does not fit the evidence. It does not permit adding unsubstantiated things arbitrarily after the fact when the hypothesis is not in accordance with the evidence. The site that was referenced and the empirically derived calculations of sensitivity by George White totally add up. I've never seen the fundamental science, calculations and logic presented there adequately disputed anywhere. If you believe you have clear evidence that contradicts it, present it in detail and we'll discuss and debate it.
  7. archiesteel (RE: Post 31), Just look at the icecore data from Vostok, for example. The amount of warming we've experienced in the last 100 years of about 0.6 degrees C is not only within the range of natural variability - it's below average. Over the last 10,000 years the average amount of temperature change per century is roughly 1 degree C - with some 100 year periods seeing as much as 2 degrees C:
  8. @RW1: again, that has been debunked over and over again. First, most of the CO2 has been added to the atmosphere in the past 40 years. Second, it takes quite a while for the entire impact of CO2 to be felt, so some of that temperature increase is still "in the pipeline." Third, I don't believe you get 75% of the increase you'd get from doubling CO2 from a 35% increase in its concentration. I'd be curious to see where you got those figures - hope it's not from that same website. Fourth, the current temp increase is 0.8C, not 0.6C. "and that's only if you assume all the warming was from CO2 (highly unlikely)" CO2 + Feedbacks. It's not "highly unlikely", but rather very likely that the greater part of the warming is due to CO2 increase, and you have not provided any evidence to the contrary. "I've never seen the fundamental science, calculations and logic presented there adequately disputed anywhere." May I suggest that you actually look at peer-reviewed litterature rather than seeking confirmation for what you already believe from random web sites on the Internet?
  9. RW1 writes: "Due to the logarithmic response of CO2, an increase from 280 ppm to 380 ppm equals about 75-80% of the forcing from a doubling of CO2." Forget about learning the science... you aren't going to get anywhere until you learn math. ln(380/280)=0.305382, or about 31%... not 75-80% Also: "75% of 3 degrees C is 2.25 degrees C." Which, in addition to the incorrect starting factor, would assume that all the warming feedbacks were instantaneous... which is not what climate science projects. It will take decades after any given CO2 level is reached for all the FAST feedbacks to play out and centuries for slow feedbacks to complete. Also: "During the period from about 1900-2000, the amount of warming was only about 0.6 C" The CO2 level at 1900 was higher than 280 ppm... so you are also using different base periods for your calculations of percentage increase of CO2 vs warming purportedly caused by this percentage increase. Finally: "...less than 1/3rd of the predicted amount, and that's only if you assume all the warming was from CO2 (highly unlikely)." The figure of 3C from a doubling of CO2 you cite is the amount climate science projects from CO2 and fast feedbacks not CO2 alone. If you correct for the host of errors identified above you will find that based on the increase of CO2 levels observed so far we'd expect, and have observed, temperature increases of about 0.8 C globally since CO2 rose above 280 ppm. In short, projections of 3 C warming are right on track... which is precisely why that IS the average projection... because it is what observations thus far suggest is most likely.
  10. @RW1: cherry-picking. That graph is for a single region, not a global average. It is well known certain areas see greater variability, especially near the poles. For example, the current Arctic anomalies are more than twice the global one (which is 0.8, not 0.6), putting them in the high end of what this graph shows. Never mind the fact that most of the warming has occured over the last 40 years, not century. Nice try, but this has been debunked here countless times. Perhaps you should actually learn the science on this site before arrogantly claiming to overturn decades of climate science with your old and tired talking points?
  11. RW1 feedbacks are not included in the 4 W/m2 and you're still separating the whole system into two parts. It does not work this way. Try the enrgy balance of the earth as a whole.
  12. Riccardo (RE: Post 36), I know the feedbacks are not included in the 4 W/m^2 (2 W/m^2 net) - that is why the actual response is greater than 2 W/m^2 or about 3.2 W/m^2 (or 6.4 W/m^2 if all the absorbed power is assumed to be directed back to the surface). The point is even if all the power is directed back down, the temperature increase would still only be about 1.2 C, which is significantly less than the 3 C predicted (390 W/m^2 + 6.4 W/m^2 = 396.4 W/m^2 = 289.2K). No one has yet to really address the initial question, which is what's so special about 1 W/m^2 additional of power from CO2 that the system is all of the sudden going to treat it as being at least 5 times more powerful than 1 W/m^2 of power from the Sun?
  13. RW1 "4 W/m^2 would the total that affects the surface only if all the absorbed power is directed back toward the surface, but only about half of it does because GHG infrared absorption and re-radiation is in all directions - i.e. about half goes down and other half goes up out to space in the same general direction it was already headed" I have already pointed out twice that this is simply plain wrong. The point on emissions being both up and down is irrelevant - the calculation already takes account of the fact that emission is isotropic. No amount of you baldly stating the opposite makes the fact go away. Doubling CO2, devoid of feedbacks, adds 4W/m2 to the Earth's energy budget. When you insist on quoting again and again, without references something plainly wrong, there's no point in any "debate".
  14. VeryTallGuy (RE: Post 38), I'll break it down into a series of questions: 1. Do you agree that the infrared power at the surface is on its way up out to space when it gets absorbed by GHGs (i.e. CO2)? 2. Do you agree that when re-radiated, half of the power absorbed is directed upward out to space and the other half is directed downward toward the surface? 3. Do you agree that all infrared power at the surface that isn't absorbed goes directly out to space? 4. Do you agree, therefore, that re-radiated power that is directed up out to space is same as power that was never absorbed to begin with? 5. Do you agree that about 4 W/m^2 is the total absorbed power from a doubling of CO2? 6. Do you agree that half of 4 W/m^2 is 2 W/m^2?
  15. CBD said: "ln(380/280)=0.305382, or about 31%... not 75-80%" But ln(2) is 0.693 so it should be 44%, not 31%, and not 75-80% in post 31
  16. Eric and CBD, The response of incrementally more CO2 is not linear - but logarithmic, which means each additional amount added only has about half of the effect of the previous amount. This is how and why I'm getting about 75-80% when going from 280 ppm to 380ppm. What this also means is that the remaining 180 ppm to get to a doubling of 560 ppm will only have about 20-25% of the effect as the first 100 ppm
  17. RW1 no one addressed your question because it makes no sense. As I'm trying to explain your reasoning is wrong beacuse you mix what happens at TOA with what happens at the surface. You should work out the correct energy balance starting with a simple zero-dimensional model.
  18. As I pointed out in another thread quoting Mombiot, I'm afraid that some trolling need to be taken into account. The obstinacy in certain errors and the conceitedness of having found a "significant hole in the AGW theory" with a few (wrong) back of the envelop calculations are typical; the tactics in the dicussion are also always the same. Sound familiar.
  19. Riccardo (RE: Post 42), Explain to me what is happening at the TOA vs. what is happening at the surface. I need some specifics. I understand that an imbalance at the surface from a increase in radiative forcing will be offset by radiating out more power at the TOA to compensate - to achieve equilibrium. Is this what you're saying?
  20. Riccardo (RE: Post 43), I'm sticking to the science via civil discourse. And for the record, I don't believe that the 2nd law of thermodynamics contradicts the greenhouse effect or global warming theory at all. I don't dispute that increased CO2 likely has some warming effect - I'm just presenting empirically derived evidence and logic that suggests the magnitude of the warming predicted - 3 degrees C, is simply much too high.
  21. #45. RW1 - I'm sorry but you are damorbel and I claim my £5! (http://en.wikipedia.org/wiki/Lobby_Lud)
  22. @RW1: you're not sticking to the science - in fact, you have failed to provide evidence that point to climate sensitivity being lower than 3C. The 0.8C increase in temp is in line with what models predict for a 3C sensitivity.
  23. Can I say I am confused about what is actually being argued about here? A TOA energy imbalance implies earth is storing energy - this make future temperature rise inevitable but surely this is information about current energy imbalance. Since 1750, top of tropopause downward radiative forcing is 2.9W/m2 due to change in GHG composition. Would this be the more relevant number?
  24. archiesteel (RE: Post 35), Vostok is in Antarctica - not the Arctic, which I know is more variable than global averages. Antarctica is considerably less variable than the Arctic. Even if you assume the global averages were only half of what Vostok depicts, that still means the amount of warming we've seen is only about average or maybe a little above. The 0.6 C rise was from 1900-2000 (i.e. 100 years), not necessarily the total rise since we've been measuring, which I don't doubt is about 0.8 C.
  25. RW1 at 05:36 AM on 20 December, 2010 RW1 at 08:50 AM on 20 December, 2010 That's all incorrect RW1 (and note [***] below) You can calculate the warming expected at equilibrium from an increase in atmospheric [CO2], very simply: delta T = (ln([CO2]final/[CO2]start))*S/ln(2) where delta T is the change in temperature at equilibrium from increasing atmospheric [CO2]start to [CO2]final, for a climate sensitivity of S (oC per doubling of [CO2]). For your 280 ppm to 380 ppm, the warming at equilibrium for a climate sensitivity of 3 oC, is: 1.31 oC The temperature rise from the period when [CO2] was 280 ppm (early-mid 19th century)[***] to 2000 is around 0.9 oC. Since the Earth has a substantial inertia to warming, we certainly haven't attained equilibrium with respect to warming from the enhanced greenhouse forcing. Likewise we know that a significant amount of the warming from enhanced greenhouse forcing has been offset by anthropogenic aerosols. The solar contribution to warming is known to be small over this period (no more than 0.1 oC); note that a small part of the warming is from non-CO2 anthropogenic sources (methane, and nitrous oxides). for a climate sensitivity of 2 oC the expected temperature rise is 0.88 oC. This is a small part of the reason that climate sensitivites below around 2 oC are simply incompatible with empirical observation. In other words we've already had the warming expected from a climate sensitivity of 2 oC, without taking into account the climate inertia and the effects of aerosols. The empirical data are generally consistent with a climate sensitivity near 3 oC (per doubling of atmospheric [CO2]. [***] you have mismatched 280 ppm with 1990. In fact in 1990 atmospheric [CO2] was already near 300 ppm (297-298 ppm; see D. M. Etheridge et al (1996) "Natural and anthropogenic changes in atmospheric CO2 over the last 1000 years from air in Antarctic ice and firn J. Geophys Res. 101, 4115 -4128), and your expected temperature rise should be 1.02 oC for a climate sensitivity of 3 oC (we had around 0.75-0.8 oC of this to 2000...)

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