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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 151 to 175 out of 191:

  1. #150: "Check out this ... " Why am I not surprised? I asked you if that website was your source 130 comments or so ago. Where is the published science from this 'originator'? Who are the other authors who've gone on to cite the 'originator'? That site (which begins with nonsensically throwing out 'anomaly analysis') seems to be the basic source for everything you've presented here. To the extent that Lindzen and Choi are debunked here and the extent that you've been shown to be incorrect, that site goes down the debunking trail too.
  2. @RW1: "I've never seen the information and analysis he presents here refuted anywhere" Has he every published in a peer-reviewed journal? The fact that you hold him in high esteem is quite meaningless; in fact, if he gets the same results as Lindzen and Choi are getting, he's likely just as mistaken as they are. Too bad your skepticism is only directed towards those you disagree with, and not those who reinforce your initial position. Meanwhile, many people here have successfully rebutted your assertions, and you have yet to offer a counter-argument. I guess we'll just have to take that silence as an admission of defeat on your part.
  3. @muoncounter: hey, maybe RW1 *is* George White. That would explain a lot, actually... :-)
  4. RW1, the (lack of) perihelion increase is just another example of nonlinearity in the effects of forcing. The increased solar power hitting the SH is absorbed in the oceans which smooths the extra forcing much more evenly than the NH can. One bit of interesting evidence is that part of the Milankovitch theory is that seasonal extremes melt the ice and release us from an ice age. This occurred 11k years ago when the perihelion was in July and the summer extremes melted the NH ice.
  5. RW1, it looks like the consensus is that site will provide some good practice in spotting incorrect assumptions, logic or math. I can't guarantee anything, but I'll give it a try tomorrow.
  6. Eric (RE: Post 154), "RW1, the (lack of) perihelion increase is just another example of nonlinearity in the effects of forcing." How do you figure?
  7. Eric (RE: Post 148), Eric: "RW1, the sun, measured by TSI changes in the historical measurements and proxies, increased by about 0.5 W/m^2 from the depths of the Little Ice Age to about 1900, see fig. 1 in A-detailed-look-at-the-Little-Ice-Age.html The temperature increase, which also involved other factors, was at least 0.5C, maybe more like 1C. With no other factors considered the "gain" is something like 2.5 to 5W/m^2 divided by 0.5 which is 5 to 10, rather than 1.6 The problem, I believe, is you are calculating gain with full solar input (zero to current day) which will yield a much smaller result than a delta of solar input as I demonstrated, albeit crudely, using the LIA." You're assuming the temperature increase was caused entirely by the 0.5 W/m^2 increase in solar power. The overwhelming majority of it could have been caused by a countless number of other things or combination of things - most of which we still don't know. It's well known that the very small increases in total average solar radiance are not enough to cause the warming we've seen since the LIA.
  8. "that site will provide some good practice in spotting incorrect assumptions, logic or math" Indeed. Starting with this one: According to HITRAN based simulations, the atmosphere captures 3.6 W/m² of additional power when the CO2 is increased from 280ppm to 560ppm. Of this, the atmosphere radiates half of this up and half down. One of us doesnt understand what HITRAN outputs mean. It seems the site author is also eccentric in usage of word "power". I had no luck finding publications by George White in physics and climate. Anyone else done better?
  9. Eric, To show you that the global temperatures being 3 C colder at perihelion still coincides with the average gain factor of about 1.6 for net incident solar power, here are some calculations: At perihelion in January, the albedo is closer to 0.4 or nearly 0.1 higher than it is on average. So if we take the increased solar power at perihelion of 347 W/m^2 and subtract out an albedo of 0.4, we get net incident solar power of about 209 W/m^2 (347 x 0.4 = 138; 347 - 138 = 209 W/m^2). At 3 C colder, the earth's average temperature is about 285K. 285K = 374 W/m^2 from S-B. 374 W/m^2 divided by 208 W/m^2 equals a gain of about 1.8, which is not far off from 1.6. The albedo is actually not quite 0.4 in January on average, so if we used .37 instead, it comes to a gain of about 1.7, which is pretty close to 1.6.
  10. #159: "At perihelion in January, the albedo is closer to 0.4" Your website's graph 'global monthly albedo' shows the average at 0.27 and appears to put the NH winter seasonal difference 'limit' at 0.032. Thus, in January, according to your figures, the albedo is closer to 0.3. The bulk of this change (as labeled) is due to 'ice amount'. This is used as some form of input to a 'power' equation. Do you include the fact that NH solar insolation above 60N lat is sharply reduced during winter months? So while there is higher albedo due to the greater ice extent, there is very little sunlight falling on that reflective surface. How can there be any material alteration to what you call your 'power' calculation due to these purely seasonal changes? What, then, does this 'gain' actually mean? Please note these questions are not an invitation to merely restate what you've already said here numerous times.
  11. Eric, I'm sorry again. The increase in average solar power at perihelion is actually 350 W/m^2 - not 347 W/m^2. When this is corrected for, the gain calculation for a 0.4 albedo is about 1.78 and for a 0.37 albedo is 1.7 - pretty close to 1.6. Also, the original gain calculated from 288K is actually 1.64 (390/238 = 1.64). So again, it's very close and certainly same ball park. Most importantly, it's no where near 8 or significantly less than 1.6.
  12. muoncounter (RE: Post 160), I wasn't getting my albedo numbers from that sight, but I don't think you are interpreting the graph there correctly. The referenced limit is the amount from the dashed line to dotted line, and the peak albedo is actually above the dotted line - making it greater than 0.304. So what numbers do you want to use for average yearly albedo vs. average albedo in January? I've been using a round 0.3 yearly average. How about we use 0.34 then for January? That yields a gain of 1.63.
  13. muoncounter (RE: Post 160), "The bulk of this change (as labeled) is due to 'ice amount'. This is used as some form of input to a 'power' equation. Do you include the fact that NH solar insolation above 60N lat is sharply reduced during winter months? So while there is higher albedo due to the greater ice extent, there is very little sunlight falling on that reflective surface. How can there be any material alteration to what you call your 'power' calculation due to these purely seasonal changes? What, then, does this 'gain' actually mean?" I don't get the question. The numbers used and inputed for each variable are global averages, so all of what you mention is automatically accounted for.
  14. I'm pretty sure discussing perihelion insolation and albedo is quite off-topic. Please stop bloating the thread with such confused, irrelevant and repetitive arguments. Thanks.
  15. RW1, you're simply not listening, I'm done. Riccardo @141 do you have a reference or link for how the calculation for surface heat flux change and therefore temperature change is done from the TOA 3.7W/m2 ? As I said in the post, conceptually I'd expect the surface change to be larger, but I'm interested if a rough methodology is available to work through.
  16. VeryTallGuy I haven't seen any rough calculations and I don't think it is possible. The problem is that you need to consider the wavelength dependence of both emission by the earth surface and absorption by the atmosphere; also, other forms of energy other than radiative need to be taken into account. In other words, you're asking for the climate sensitivity which proved to be hard to calculate.
  17. Riccardo, I found this excellent exposition of the concepts by Chris Colose It turns out that the definition of the no-feedback temperature increase for a forcing is based on the effective emission temperature rather than the actual surface temperature. Using 255K as the effective temperature (that of a notional blackbody with overall emission equal to total net insolation TOA) that gives 1K for 3.7W/m2. I guess that the often quoted 1.2K comes from working through the calculation to give the surface budget accurately for real temperature, without feedbacks, but applying it directly to the effective temperature gets approximately the same answer much more simply. RW1 - if you want to understand this better, Chris's post includes how to calculate for solar forcings, albedo etc.
  18. In the past, I've pointed out that most of our regular "skeptic" commenters appear to follow an unwritten rule never to say anything critical of another's "skeptic" arguments, no matter how far-fetched. So I have to note here how much I appreciate the tone set by Eric (skeptic), who has been very calmly and even-handedly responding to comments from both the pro-consensus and anti-consensus "side" in this thread. This is a real breath of fresh air ... and it's very reassuring to those of us who have been starting to wonder whether there's anyone on the "skeptic" side whose comments here are worth taking seriously. We need more of this. John has created a really great site here, but it's constantly in danger of succumbing to the typical pattern of two noisy "sides" yelling at each other. Anything that tends to break down the homogeneity of these two "sides" is a good thing, IMHO.
  19. Thanks for the praise, Ned. I read all the threads here (or at least the head post) and choose carefully where I can understand and respond to science issues. As I said on another thread, I was brought here after I spewed some "talking point" without doing proper research over on a weather forum that has occasional climate opinion pieces. I have two goals here, to hopefully never make claim that I haven't researched, and second to get critiques of my own, sometimes outlandish-sounding theories. In order to do the second, I have to explain what I mean very carefully which is great practice for the long run. If I can make one useful contribution to the site it would be if someone takes one of my explanations above and cleans it up and turns it into a post, e.g. why lack of warming in the perihion does not disprove sensitivity or something like that.
  20. I would have to second Ned's comment. Eric, if you are not actually a scientist, then you are thinking like one. You would be welcome in our tea room anytime.
  21. VeryTallGuy (RE: Post 165), The questions I asked were perfectly reasonable.
  22. No one here has adequately debunked anything I've said. No one has yet to explain what is so special about each 1 W/m^2 of additional forcing from CO2 that the system is going to treat it as being 5 (or at least 2.5 times) as powerful as each 1 W/m^2 from the Sun. No one has yet to explain why the oceans will obey radically different physics globally than they do hemispherically to increases in radiative forcing. A few people have acknowledged that of the additional absorbed power from CO2, only half of it can affect the surface because the other half is radiate upward out to space. When asked for a source or some kind of documentation that for the total net forcing to be 3.7 W/m^2, the total absorbed actually need to be 7.4 W/m^2, no one has provided it. Now, I know must have missed answering some questions directed to me here, so please remind me of anything I failed to address to anyone's satisfaction.
    Response: [Daniel Bailey] You have been repeatedly corrected, most recently by KR at 174 below. Please read his comment carefully and review the previous comments others have made. Thank you.
  23. Eric (RE: Post 169), What numbers would you like to use for the yearly average albedo vs. the average albedo in January? I now realize 0.4 is too high, and it appears like it's more around 0.33-0.35. Do you see that the 3 C colder temperature at perihelion doesn't conflict with the increased solar power and the roughly 1.6 gain factor, and is actually in line with it?
  24. RW1 - Quite frankly, it's difficult to know where to start. - The 3.7 W/m^2 forcing for a doubling of CO2 leads to a 1.2°C warming without considering feedbacks. That means 3.7 W/m^2 less IR radiation leaves the atmosphere. That number is the result of a considerable amount of computation, more than I can fit on the back of an envelope, working from basic physics to find how much energy is retained by GHG's. That's equivalent to a 3.7 W/m^2 forcing from solar changes (1.2°C for each 3.7 W/m^2 change), a 3.7 W/m^2 change in volcanic aerosols (1.2°C for each 3.7 W/m^2 change), etc. - Your 'halving' of the 3.7 radiative forcing is nonsense. You've been told that repeatedly, and have not responded. CO2 absorbs all the IR within it's emissivity/absorptivity bands within a matter of meters at ground level pressures. And emits based on it's temperature, somewhere near dynamic equilibrium. It's not just a single-layer atmosphere (where 7.4 W/m^2 absorption of surface IR would account for that); you would have to look at the integrated spectra of surface level IR absorption, the numeric calculations of each layer of atmosphere, etc. But it's 3.7 W/m^2 not making it out of the atmosphere for each CO2 doubling. - Your 1.6 gain makes absolutely no sense to me, nor to any number of other posters. You appear to be dividing apples by oranges. - Your peak-to-peak insolation numbers are meaningless without averaging them over the season; they should be ~50-60% of the peak-peak values (off the top of my head) for seasonal averages. - Climate sensitivity amplifies (to some extent) that change, with the current estimates being ~3°C for a doubling of CO2. - Your raw number calculations for insolation do not include sun angle; that will change those raw numbers considerably. - Seasonal changes are cyclic, which means they average out to a trend of zero (0°C) over time. Seasonal variability is quite large - but the trend over time (30 years for statistical significance) is non-zero, indicating global warming. - The difference between seasonal heating/cooling and long term trends is, quite simply, the trend. Seasonal effects cancel out, trends on baselines do not. - Evaporation and convection in the Trenberth numbers count; very much so. The Trenberth 2009 energy budget is essentially a 3-layer layout: 3-way exchanges between outer space, the surface of the Earth (water and soil), and the atmosphere. All numbers are important. You've indicated that you feel Trenberth was just presenting ad hoc numbers, as I indicated in this post, you're going to have to demonstrate your objections to specific numbers in those budgets to be taken seriously. Given the large number of incorrect or unsourced assertions in your postings, I would find it very difficult to discuss anything with you. You really appear to be focusing on details (bean-counting) without a good view of what's happening on a larger scale, and are getting tied up in the (incorrectly summed) numbers.
  25. Hi RW1, sorry I haven't answered your 172 post yet. I am looking at the paper you linked that said "According to HITRAN based simulations, the atmosphere captures 3.6 W/m² of additional power when the CO2 is increased from 280ppm to 560ppm. Of this, the atmosphere radiates half of this up and half down." and looking at the Collins paper http://www.cgd.ucar.edu/cms/wcollins/papers/rtmip.pdf and others linked from Judith Curry's site http://judithcurry.com/2010/12/05/confidence-in-radiative-transfer-models/ So far I have not found a complete derivation of such a quantity as "captured additional power" for the atmosphere but a changes in LW forcing at various levels in the atmosphere. Hopefully I can reconcile those and determine whether the "divide by 2" idea is valid or not.

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