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Comments 1 to 50 out of 65:

1. Paul from VA at 07:01 AM on 22 February, 2012
   Typo in your first sentence, Forbes article is Feb. 2012, not 2011.
2. MA Rodger at 07:17 AM on 22 February, 2012
   You cite Hansen & Sato 2011 for the 1.2 degC for 'direct' 2xCO2 warming. Okay it's good and recent, but what's wrong with the more authoritative 1.2 deg C (+/-10%) IPCC AR4 2007.
   For myself, when I hear somebody saying the figure is 'somewhere near 1 degC,' I find it almost always is followed by a bunch of obvious denialist statements.
3. jg at 08:53 AM on 22 February, 2012
   Thanks Paul. I'll correct the typo. Thanks MA Rodger: 1.2 +/- 10% is more accurate.
4. Byron Smith at 12:46 PM on 22 February, 2012
   "If a long slow wobble (precession) was sufficient for Earth's feedbacks to raise the global temperature 8-12 degrees, we should be cautious, wary, risk-adverse of a global disturbance of 1 degree C, as this one degree disturbance occurs on top of an interglacial."
   
   I assume that the graph labelled "Temperatures and Sunlight" is in ºF rather than ºC, which makes the above sentence somewhat confusing. I've read in many other places that the end of the last glacial was associated with a rise in global surface temperatures of about 5-6ºC (which is roughly 8-12ºC).
5. chriskoz at 14:25 PM on 22 February, 2012
   Byron @4,
   
   You are incorrect in your assumption that above temps are scaled in F.
   Temp anomalies in ice cores do span indeed 6-8K (or degC), as we've shown here:
   
   http://www.skepticalscience.com/co2-lags-temperature.htm
   
   whereas the anomalies in a similar graph scaled in F, do span ~20F, (interestingly the denialist sites are more likely to scale it in F), e.g. here:
   
   http://stevengoddard.wordpress.com/2011/06/19/vostok-cores-show-zero-climate-sensitivity-2/
6. Bernard J. at 14:45 PM on 22 February, 2012
   It would seem that Myers is attempting to undermine the type of challenge that I and many others often put to deniers, where they are asked to specifically explain at what point they digress from the science that supports global warming, and its sequelæ. My own challenge used to amount to around 10 questions, but the most recent iteration poses 11:
   
   1) Is the planet warming?
   2) Is the planet warming as much as climatologists say?
   3) Is CO₂ a 'greenhouse' gas?
   4) Is the concentration of atmospheric CO₂ increasing?
   5) Are humans causing the increase in the concentration of atmospheric CO₂?
   6) What is the contribution of CO₂ to the observed contemporary global warming?
   7) What is the sensitivity of global temperature to a doubling of atmospheric CO₂?
   8) What will be the abiotic consequences of warming resulting from a doubling of atmospheric CO₂?
   9) What will be the biological/ecological/agricultural consequences of warming resulting from a doubling of atmospheric CO₂?
   10) What will be the political/social consequences of warming resulting from a doubling of atmospheric CO₂?
   11) What ethical/moral responsibility do polluting nations have to non-polluting countries, to future generations, and to the non-human species on the planet?
   
   It seems that Myers and his ilk find such questions uncomfortable because such scrutiny results in a dissection of their ideology. Myers seems to be reversing the investigative train that attempts to locate a denier's divergence from science, and pretending that the whole issue of the danger of global warming will disintegrate if enough doubt is sown about the components.
   
   Myers says:
   
   

   Its probably irresponsible to call anything in a science so young as climate “settled,” but the fact that increased atmospheric CO2 will warm the Earth by some amount is pretty close to being universally accepted.

   
   
   Note how Myers, without substantiation of his claim, repeats the denialist lie that climatology is a "young" science": with a century and a half of work behind it, climatology is NOT a "young" science. Note also how Myers slips in the concept of irresponsibility, and how he introduced both of the preceding concepts before casually throwing in the concession that CO₂ will warm the planet by "some amount", in a manner that itself appears intended to cast the increase as being insignificant.
   
   Myers subsequently repeats the notion of "debate" a number of times, without explaining how much debate or otherwise there actually is in the scientific arena. It seems that he is using the term as a rhetorical device to subliminally implant doubt in the minds of his readers.
   
   As jg notes in the OP Myers basically ignores the influence of feedings-back. But not only does he do this, and not only does he round down sensitivity to 1 C as jg observed, but he completely mangles his arithmetic:
   
   

   While some of the talk-show-type skeptics have tried to dispute this greenhouse theory, most of what I call the science-based skeptics do not, and accept a number circa 1C for the direct warming effect of a doubling of CO2.
   
   So what’s the problem? Why the debate? Isn’t this admission a “game over” for the skeptics? Actually, no. To understand this, let us do a bit of extrapolation. Current CO2 concentrations in the atmosphere today are around 390ppm, or about 0.039%. But even if we were to hit a relatively pessimistic level of 800ppm by the end of the century, this would, by the numbers above, imply a warming of about one degree.

   
   
   Wrong. Completely wrong.
   
   Even at a 1 degree celcius sensitivity, an increase of atmospheric CO₂ concentration to 800 ppm would result in almost 3 degrees celcius of warming. This is because the reference concentration for sensitivity is the pre-Industrial atmospheric CO₂ concentration (~280 ppm), and not the present atmospheric CO₂ concentration.
   
   Myers is demonstrating that he doesn't know what he's talking about. And if he does understand the mathematics underpinning sensitivity - well, forum protocol prevents me from making explicit accusations, but in my own personal opinion he would, in such an instance, be lying.
   
   Now, even with a rounded-down sensitivity and with no feedback, going to 800 ppm atmospheric CO₂ concentration and a concommitant 3 degrees celcius warming would be "catastrophic" for much of the biodiversity and agriculture/horticulture of the planet. That Myers does not understand or acknowledge this shows his complete ignorance of human-, crop-, and eco-physiology, as well as of the long-term abiotic responses to that amount of warming.
   
   Myers uses many FUD words such as "second chained theory" (?), "assumed", "exaggerated", "Al Gore", "flat [sic] surface temperatures","missing heat", "Lions and Tigers and Bears, Oh My [indeed...]", "purportedly", and so on. I differ with jg on the non-necessity of debunking Myers' wide suite of scientific garbage, but I certainly acknowledge that it would take a whole chapter's-worth of writing to address it all. The guy is a veritable fountain of garbage.
   
   Oo, and not that I am one to speak, and not that it's of any direct consequence, but Myers' grammar and vocabulary are both dismal. The piece doesn't even seem to have been run past an editor, but if it had it would be invisible under all the red lines...
7. Bernard J. at 15:37 PM on 22 February, 2012
   Erm, I should watch where I'm putting my fingers. I meant:
   
   

   ...result in almost 2 degrees celcius of warming.

   
   
   Which, of course, is still regarded as a significant increase, as (failing) efforts to restrict current increases to below this target demonstrate.
8. Tom Curtis at 15:37 PM on 22 February, 2012
   Bernard J. @6, while I admire your fervour, your maths is wrong.
   
   An increase of CO2 levels over pre-industrial levels to 800 ppmv would result in a forcing of:
   
   5.35 * ln(800/280) =~= 5.6 W/m^2
   
   The forcing for doubling CO2 concentrations is 3.7 W/m^2, so if that caused just 1 degree C of warming, then the 5.6 W/m^2 would cause approx 1.5 degree C of warming, or around 0.7 degrees C additional warming relative to the warming already experienced. That would be welcome news indeed.
   
   The problem is, an increase of only 1 degree C per doubling of CO2 is extraordinarily unlikely. Not only is it well outside the IPCC expected range, but it becomes very difficult to explain why we have seen a 0.8 degree C increase in temperatures from the 1.8 W/m^2 increase in CO2 forcings seen since the industrial era, especially given that the climate response is slow and takes decades to reach the equilibrium response.
   
   Even if we hold out for the one in twenty chance that climate sensitivity for doubling CO2 is only 2 degrees C, that still represents 2.2 degrees additional warming for the 800 ppmv scenario, and takes us beyond the guardrail beyond which the consequences of Global Warming are not just deleterious, but potentially catastrophic. Assuming just a 2 degree C climate sensitivity represents the hail mary pass of climate policy. Assuming 1 degree C is a hail mary pass from a drunk, blindfolded quarter back.
9. jg at 16:25 PM on 22 February, 2012
   Byron: I apologize. I should have included the temperature unit in the graphs. I'll correct this. I too have read 5-8 deg C change between glacial and interglacials. However, I meant to highlight just the rapid onsets that start out colder than the preceding glacial and end up hotter than the following interglacial. E.g., at ~342,000-334,000 ybp, I see jumps from -9.56 to +3.5 C. This part of the temperature record makes the abstract risks of warming-amplifying feedbacks more concrete to me.
   
   Bernard, thanks for adding what my post left out.
   
   jg
10. owl905 at 17:43 PM on 22 February, 2012
    Added to Tom Curtis @8 - if the real world only reacted 1dC of warming to 2xCO2e, the glacial to interglacial climate transition is inexplicable. Milankovich cycles give it the kickstart, but takeoff co-incides with GHG increases, and the total rise of 7dC is a mismatch to the ~50% rise in GHGs.
11. Bernard J. at 18:39 PM on 22 February, 2012
    Tom.
    
    I should probably have been more explicit in my posts at #7, and originally at #6.
    
    My original rounding was to 2, although I mistyped "3" in my post at #6. The actual figure I calculated for an increase in temperature resulting from an increase of atmospheric CO₂ concentration from 280 ppm to 800 ppm, assuming a sensitivity of 1 degree celcius per doubling of CO₂, was 1.51 degrees celcius over pre-Industrial levels. The reason I rounded to 2 was because Myers said:
    
    

    But even if we were to hit a relatively pessimistic level of 800ppm by the end of the century, this would, by the numbers above, imply a warming of about one degree.

    
    
    By using the phrase "about one degree" Myers was trying to make the value sound insignificant,and possibly even less than one degree. I was simply pointing out that a better 'approximation' would have been "almost 2 degrees", as I used, which rounds to the same number of significant figures but which is essentialy double (in the minds of those reading) the value with which Myers tried to trick his readers.
    
    Had I more time when I typed the earlier posts I would have tried to explain it a little more, but I was about to head out for a meeting and I probably rushed the explanation more than I should have.
12. Tom Curtis at 18:55 PM on 22 February, 2012
    Bernard J. @11, If you are going to round to a single digit than 2 is certainly better than 1 for total warming. However, it appears Myers has calculated the radiative forcing of 800 ppmv relative to 390 pppmv, which is 3.84 W/m^2 equating to 1.04 degree C of warming if the climate sensitivity per doubling of CO2 is 1 degree C. What is neglected in his calculation is that the Earth is not in radiative equilibrium, so he has to add on to that figure the warming which is currently in the pipeline.
    
    Regardless, suggesting the the climate sensitivity is only 1 degree C per doubling is just absurd. As can be seen from this figure derived from Knutti and Hegerl,the probability that the climate sensitivity for a doubling of CO2 is 1 degree C is indistinguishable from zero (see the combined evdence).
    
    
13. Bernard J. at 21:18 PM on 22 February, 2012
    I'd typed another addendum but whilst wrestling a brood of small children to bed Tom said essentially the same thing (although much better) in the interim.
    
    Still, for the sake of saying it...
    
    If climate sensitivity really was one degree per doubling of CO₂, then we would have expected only around 0.48 of a degree increase in global temperature to 2011. Given that we've already seen 0.74 of a degree increase, without having reached equilibrium, Myers' assumption on sensitivity is out by probably at least a factor of two.
    
    And if one assumes that Myers was talking about warming that is to follow from the present, he needs to remember that we've already experienced that 0.74 of a degree - a small fact about which he seemed to want to avoid reminding his audience...
    
    In business one does not cavalierly forget to declare a significant proportion of one's profits or losses: why does Myers think that it's OK to do so in climatological accounting?
    
    Unless of course one is trying to lead the shareholders...
14. Eric (skeptic) at 23:31 PM on 22 February, 2012
    This post demonstrates some misconceptions about the applicability of the paleo record ("if this gave us this, what will this give us?") In the paleo chart arming oceans were a net source of CO2 which provided positive feedback to the warming ("cyclical warming gave us CO2 which gave us more warming"). Currently oceans are a net sink. Due to that fact alone, the current rise will give us a lot less warming than the depicted paleo CO2 rise did.
    
    Second, the argument given above ignores numerous non GHG forcing factors as outlined in The Last Interglacial Part Two - Why was it so warm?
    
    Third, the paleo argument ignores the other feedbacks: ice albedo, dust, water vapor etc which worked in tandem with the CO2 feedback.
15. Dikran Marsupial at 23:56 PM on 22 February, 2012
    Eric (skeptic) I don't see how you have come to the conclusion in your first paragraph. The warming we should expect to see depends on the amount of CO2 in the atmosphere, not the magnitude or direction of fluxes that result in it being there. Unless climate sensitivity has changed, the similar amounts of CO2 radiative forcing will have similar effects on the climate. Please can you clarify.
16. Bernard J. at 00:55 AM on 23 February, 2012
    Eric (sceptic).
    
    What Dikran Marsupial said.
    
    What makes you think that calculations of contemporary forcing do not account for the various fluxes of CO₂?
    
    And what makes you think that analyses of paleo- and contemporary warming do not account for other forcings and feedings-back? If you have referenced evidence I would be most keen to see it.
17. KR at 01:07 AM on 23 February, 2012
    Eric (skeptic) - "Third, the paleo argument ignores the other feedbacks: ice albedo, dust, water vapor etc which worked in tandem with the CO2 feedback."
    
    Actually, paleo evidence is a very strong indicator of total feedback - to the extent that we can clearly identify the forcing (such as Milankovitch cycles of insolation) the paleo record gives the total temperature change due to that forcing, and hence the sum of the forcings and all feedbacks.
18. KR at 01:12 AM on 23 February, 2012
    To extend my last comment a bit - temperature response to forcings gives the total feedback, while other proxies or direct evidence (such as ice-core CO2 levels) helps break out various individual feedbacks such as CO2 response.
    
    Again, paleo evidence provides one of the most straightforward indications of total feedbacks to climate forcings, within the uncertainty range of the paleo records.
19. Eric (skeptic) at 01:23 AM on 23 February, 2012
    Dikran the paleo record shows an amplification process, namely a rise in ocean temperature causing an offgassing of CO2 causing a temperature rise causing more offgassing and other positive feedbacks. Nothing in that chain depends on amount of CO2, only the changes. Bernard, the other forcings and feedbacks are modeled, thus the paleo evidence is the same as modern model-based evidence (not independent).
    
    KR, the albedo and dust feedbacks that are evident in the paleo chart above are not applicable to today's climate (e.g. see red squares)
20. Eric (skeptic) at 01:28 AM on 23 February, 2012
    KR, the answer to your #18 is that analysis of CO2 and TSI ignores forcing from weather pattern changes. An increase in convection globally, for example, will cause the GAT to be cooler, all other things being equal.
21. KR at 01:42 AM on 23 February, 2012
    Eric (skeptic) - One of the more similar paleo periods would be the Eemian Period, with temperatures 1-2C higher than present. And sea levels 4-6 meters higher, I'll note. Perhaps that would be a better comparison in your eyes than glacial periods?
    
    We're likely to exceed the Eemian temperature change given the current path; in fact, I find it hard to believe we won't.
    
    You are of course correct, in that given different situations (such as extensive ice cover) there may well be differences in climate sensitivity to forcings. I will note, however, that all of the evidence (short term observations, paleo evidence, basic physics and modeling) points to roughly the same 3C sensitivity per 2xCO2:
    
    
    
    Hence I would consider claims that climate sensitivity would be (currently) low due to differences in conditions from some paleo situations to be extremely wishful thinking, and quite frankly contradicted by the available evidence.
    
    ---
    
    Side note - I do not see how you can claim that weather patterns are excluded from paleo or other measures of climate sensitivity - since they measure the total climate system response to a forcing.
22. Stephen Baines at 01:43 AM on 23 February, 2012
    "Nothing in that chain depends on amount of CO2, only the changes. " I'm not sure what you mean by that. Are you saying the CO2 temp feedback does not depend on CO2 concentrations? I hope not, because that would be wrong. The changes are only relevant to the CO2 temp feedback because of their effect on CO2 concentrations.
23. Dikran Marsupial at 02:14 AM on 23 February, 2012
    Eric (sceptic) Thank you for clarification, I think I can now see the misunderstanding.
    
    The exchange of carbon between the oceans and atmosphere is principally governed by two factors, ocean temperature and the difference in partial pressure between the surface waters and the atmosphere. Thus the warming of the oceans that we are seeing is increasing the flux from the ocean to the atmosphere now just as it did in the paleoclimate record. However, due to anthropogenic emissions there is now an increasingly large difference in partial pressures between the atmosphere and surface waters, which pushes the fluxes in the other direction. The only difference between now and then is anthropogenic emissions, the oceans are acting according to the laws of physics in the same way now as they did then.
    
    Essentially the temperature driven outgassing is happening, it is just that it is being masked by the pressure differential driven uptake*.
    
    Unless you have an argument that climate sensitivity is different now than it was then, the effect of CO2 on global temperatures depends only on the atmospheric concentration, the details of how that came to be is irrelevant.
    
    _{* it isn't really correct to think of it as an uptake, it is more difficult for CO2 to move into the atmosphere the more CO2 it contains, and easier for CO2 to move into the surface waters the less CO2 it contains relative to the atmosphere. Thus it isn't purely uptake, but a change in the net flux.}
24. Albatross at 03:00 AM on 23 February, 2012
    Eric,
    
    This is classic obfuscation by you. This post is about Meyer's very misguided understanding of the science. What is your position on his claims? Could you please let us know specifically which of his claims you agree with or support and which ones that you do not agree with or support. And one can take it from there.
    
    Open-minded and informed climate scientists know very well that model reconstructions constrained by paleo data data from periods that were both warmer and cooler than today's current climate, including independent estimates based on data from the last 130 years or so also support a value near +3 C for a doubling of CO2. This is why people like Pielke and Lindzen avoid the paleo data like the plague because it completely undermines their claims of homeostasis and strong negative feedbacks.
    
    You continue to argue against a massive amount of very solid and robust science, multiple independent lines of evidence and last but not least basic physics.
25. Eric (skeptic) at 05:01 AM on 23 February, 2012
    KR, yes, prior interglacials are much better comparisons than glacial to interglacial transitions because of the similarities of climate base state. Do you know why Knutti and Hegerl 08 do not have that in their analysis (only LGM and Royer, Berner and Park 07 which is 420 million years of data).
    
    Dikran, thanks for the reply. The paleo depiction above shows how a temperature rise is amplified by CO2, outgassing on short timescales and other sources on longer timescales. The red dashed line ("what will this give us?") is what we would nominally get by heating the oceans by 16K according to ref 5 here http://en.wikipedia.org/wiki/Henry%27s_law
    
    Except we are only going to heat the oceans by 3C over the next few centuries so during that time the oceans will always be absorbing our extra CO2.
    
    Albatross, IMO the labels on the last figure above are not meaningful ("if this gave us this, what will this give us?"). My answer is it won't give us nearly what is implied by that figure because the oceans will absorb lots of our CO2. I either am wrong or right about that, but I am not trying to obfuscate.
26. Dikran Marsupial at 05:17 AM on 23 February, 2012
    Eric (skeptic) You are missing the point, which is that the amount of radiative forcing due to CO2 depends purely on the amount of CO2 that is actually in the atmosphere. We control the amount of CO2 in the atmosphere, not the oceans, our fossil fuel emissions are large enough to overpower the natural envrionments ability to restore equilibrium. Even if the oceans continue to be a net carbon sink, atmospheric CO2 levels won't start to go down until we cut anthropogenic emissions rather drastically.
    
    Sadly it is highly likely that the oceans will saturate at some point (possibly quite soon), which will make the required cuts in emissions needed to reduce atmospheric CO2 even sharper. This is one of the very good reasons for doing something meaningful now; it will mean we have more room for manoever later.
27. NewYorkJ at 05:34 AM on 23 February, 2012
    "IPCC assumed that strong positive feedbacks dominated"
    
    Thanks for highlighting that, as that also jumped out at me when reading the piece. On the contrary, Meyer assumed that whoever told him that was correct, or falsely assumed that positive feedbacks are assumed.
    
    Reading the comments section of that article and then the follow-up article that references his previous one, it appears Meyer does not care to engage with critics or learn from mistakes.
28. Eric (skeptic) at 05:51 AM on 23 February, 2012
    Dikran, true. My arguments about sensitivity above are a separate issue since it doesn't matter how the CO2 gets there, it will have a particular, well-understood forcing whether coming quickly from modern emissions or from slow paleo temperature rises.
29. padruig at 06:00 AM on 23 February, 2012
    I fear the discussion about this opinion piece may be misdirected.
    
    We are seeing a disturbing trend were someone without any background in any of the disciplines of climate science is given a wide public forum to express opinions about a topic that affects everyone on our planet.
    
    The authors objective isn't to argue the data or the science but to dull the general public's response to the results and conclusions of the scientific community at large.
    
    To quote "Climate of Fear" (Nature doi:10.1038/464141a) -
    
    "Scientists must not be so naive as to assume that the data speak for themselves."
30. KR at 06:03 AM on 23 February, 2012
    Eric (skeptic) - You appear to be (1) arguing for a low climate sensitivity by dismissing the applicability of paleo data (whether it comes from a warmer or colder climate). You are in addition (2) continuing to fail to acknowledge the modern observational data establishing climate sensitivity, or for that matter the models.
    
    You have (IMO) failed to support either aspect of your statements, or to present evidence that climate sensitivity is in fact lower than the ~3C/doubling estimated.
    
    I'm in agreement with Albatross. Could you please state clearly what portion of the OP critiquing Meyers assertions you feel is incorrect, and why? Because otherwise I fail to see your point.
31. skept.fr at 07:05 AM on 23 February, 2012
    On Meyers "Part 2) CO2-based warming will be amplified by feedback effects"
    
    Well, we can simply say that there is a consensus on that among the 23 independent models running for IPCC, as it can be seen on this page of AR4 2007 , with a 2,1-4,4 K range for equilibrium at 2xCO2. Scientists are free to formulate hypothesis about no-feedback ou negative-feedback response to GHG forcing, as Lindzen did with the Iris Effect. But they have to corroborate their hypothesis with observations and models. For the moment, there's nothing like that. I'm more skeptic about the robustness of "central estimate" for CS (3 K), it depends on the realism of models (for example, few in the AR4 had been coupled with carbon cycle models) and the details of these estimates will certainly change with time, for example with the new generation of Earth System Models.
32. skept.fr at 07:13 AM on 23 February, 2012
    Post scriptum (31) : I must add that the CMIP5 (future AR5) simulations give nearly the same range for equilibrium climate sensitivity, as it can be checked for example on slide 8 of this MetOffice Andrews et al 2011 conference (2,0-4,6 K for results of 9 AOGCMs).
33. scaddenp at 07:34 AM on 23 February, 2012
    "Do you know why Knutti and Hegerl 08 do not have that in their analysis (only LGM and Royer, Berner and Park 07 which is 420 million years of data). "
    
    Well watch this space, but one of the issues is simply getting good data. It is much easier to determine maximum extent of ice, say, from geomorphology than it is to determine what the minimum extent was. Building global data sets is a long, slow effort and uncertainties will always be greater than for LGM.
34. jg at 08:24 AM on 23 February, 2012
    Hi Eric: Thanks for your criticism. I accept your point about my last illustration. It implies a response to elevated CO2 levels that is proportional to that seen in the previous interglacial. Such illustrations should be accompanied by the projected forcing which is not as steep as the CO2 level. My error. I meant to show that the rate of change and expected levels of CO2 have no convenient precedent and therefore the expected changes should awaken our risk-averse qualities. My changes will acknowledge your contribution.
    jg
35. Eric (skeptic) at 08:26 AM on 23 February, 2012
    KR, the paleo chart shown at the bottom does not support the critique of Meyer. Meyer's part 2 can be rewritten as "CO2 warming will be substantially amplified by feedback effects" where "substantially" would be roughly 3C or more sensitivity.
    
    The feedbacks in the paleo record can be separated into applicable and nonapplicable. The applicable one is primarily the CO2 to warming amplification. However we have short circuited the amplifier and are applying CO2 directly so there is no feedback calculation to apply. Regarding nonapplicable, there is not much albedo or dust change compared to the glacial to interglacial transition, so those will not raise our target temperature. Other potential feedbacks are based on modern climate not the glacial to interglacial transition.
    
    The evidence for high sensitivity must therefore come from models. The last diagram in the op can be quantified without a climate model which will not have 97% consensus. I agree with the final question of the OP, which is that a better understanding is needed.
36. Eric (skeptic) at 08:29 AM on 23 February, 2012
    Hello jg, I didn't see you post before my last. The value of 97% is pretty much a straw man at this point, but perhaps you could indicate what the breadth of consensus is for high sensitivity.
37. dana1981 at 08:41 AM on 23 February, 2012
    Eric, we just discussed the climate sensitivity consensus in Monckton Misrepresents (Part 1).
38. scaddenp at 08:54 AM on 23 February, 2012
    CIMP5 has range of 2 to 4.6
    
    Regarding feedbacks - I dont get the "applicable/not applicable bit". Feedback is response to temperature change not "co2 change" or "solar change" surely?
39. Eric (skeptic) at 09:02 AM on 23 February, 2012
    scaddenp, the decrease in dust from glacial to interglacial and the decrease in albedo from glacial to interglacial are both inapplicable to the current climate. They are part of the reason temperature rose so much with relatively small forcing changes in CO2 and solar.
40. KR at 09:14 AM on 23 February, 2012
    Eric (skeptic) - Please note that CO2 solubility feedback is still present even under CO2 forcing conditions, as temperature rises will cause the oceans to absorb less CO2 than they would otherwise. The CO2/temperature/solubility feedback calculation is therefore entirely applicable.
    
    And you are still ignoring modern measurements of climate sensitivity - your statement that "The evidence for high sensitivity must therefore come from models" is incorrect.
    
    As best I can read your point, you are claiming that "due to differences in conditions paleo evidence is not applicable"? Can you point to any references that support that claim regarding paleo conditions?
    
    Note that dust and albedo are considered when calculating paleo estimates of climate sensitivity to CO2 (see Kohler et al 2010, which has considerable discussion on the topic) - you simply cannot claim that they are ignored or overlooked.
41. Albatross at 10:00 AM on 23 February, 2012
    Eric,
    
    Could you please answer my question posed to you at #24 about your position on Meyer's claims (the subject of this thread) before moving on. Thanks.
    
    And I concur with KR's comments at #30 and #40.
42. Pete Dunkelberg at 10:01 AM on 23 February, 2012
    Meanwhile getting back to Warren Meyer, he's a standard issue denier.
    
    Review:
    http://scienceblogs.com/denialism/deck.php
    Denialism is how businesses and their supporters put off, or delay, making changes for the benefit of the community. Delay is the bottom line. Often some environmental harm is being done, and basic denial takes the form:
    
    A It isn't happening
    B It isn't our fault
    C It's harmless or may even be good for people anyway.
    D The proposed remedy is either impossible or much too costly
    
    Meyer starts off with this gambit:
    

    
    Likely you have heard the sound bite that “97% of climate scientists” accept the global warming “consensus”. Which is what gives global warming advocates the confidence to call climate skeptics “deniers,” hoping to evoke a parallel with “Holocaust Deniers,” a case where most of us would agree that a small group are denying a well-accepted reality.
    

    
    As the denialism blog shows, denialism is mostly about business avoiding doing something.
    
    In a more recent article, Meyer says
    

    
    What really matters are issues like quantifying the climate feedback effect. Who the hell cares who funds the breakthrough work?
    

    
    In other words, we must wait for some breakthrough that finally convinces him to stop betting the planet on his hope that science is wrong. That's major delay, which is the bottom line of denial. Since there is only one planet we can use, the rest of humanity is held hostage until the blind rich relent.
    
    Don't bet the planet
43. Eric (skeptic) at 10:02 AM on 23 February, 2012
    KR, does the consideration of dust and albedo require a model? Although ice sheets should have pretty good proxy measurements, I'm not sure how they would input the dust data. The model would have be calibrated with relatively imprecise temperature proxy data.
    
    Albatross, I believe I answered that in #35 and raised my specific concerns with the critique of Meyer.
44. Albatross at 10:46 AM on 23 February, 2012
    Eric @43,
    
    "I believe I answered that in #35 and raised my specific concerns with the critique of Meyer."
    
    No you most certainly did not. I was very specific, I asked "Could you please let us know specifically which of his claims you agree with or support and which ones that you do not agree with or support and Meyer makes several statements in his opinion piece". Let me help.
    
    1) Meyer says:
    "We are discussing the hypothesis of “catastrophic man-made global warming theory.” "
    Nice strawman and misrepresentation of the body of evidence. Or do you disagree?
    
    2) Meyer also claims:
    "On the opposite end of the scale, many plants grow faster with warmer air and more airborne CO2, and such growth could in turn reduce atmospheric carbon and slow expected warming."
    Good luck defending that one.
    
    3) Meyer claims:
    "Rising temperatures may increase evaporation and therefore the amount of water vapor in the air, thus adding powerful greenhouse gasses to the atmosphere and accelerating warming."
    May increase evaporation and the amount of WV?! He is behind on the observational data and the Clausius-Claperyon equation.
    
    4) Meyer also says:
    "The IPCC assumed that strong positive feedbacks dominated, and thus arrived at numbers that implied that feedbacks added an additional 2-4 degrees to the 1 degree from CO2 directly."
    They assumed nothing or do you disagree? If yes, please provide supporting evidence.
    
    5) Meyer claims:
    "Not only may the feedback number not be high, but it might be negative, as implied by some recent research, which would actually reduce the warming we would see from a doubling of CO2 to less than one degree Celsius. After all, most long-term stable natural systems (and that would certainly describe climate) are dominated by negative rather than positive feedbacks."
    Are you a advocate of the notion of homeostasis Eric and do you believe that there is evidence of a net negative feedback in the system as he suggests? If yes, please provide supporting evidence.
    
    6) Meyer claims:
    "Even more important for scientists (since the oceans are a much larger heat reservoir than the atmosphere) is the fact that the new ARGO floating temperature stations have measured little or no increase in ocean heat content since they were put in service in 2003."
    That is demonstrably false, or do you disagree? If you do, please provide supporting evidence.
    
    7) Meyer claims:
    " There is no reason why warming should take a break, and we are starting to hear more frequently, even among catastrophic global warming supporters, discussion of “the missing heat.”
    Again, demonstrably false or do you, unlike the climate scientists, believe that the warming should be monotonic? If you think so, please provide supporting evidence.
    
    8) Meyer claims:
    "They took computer models, which by their own admission left out a lot of the complexity in the climate, and ran them with and without manmade CO2 in the 20th century. Their conclusion: only man’s CO2 could have caused the measured warming."
    Another demonstrably false statement and misrepresentation of the body of scientific understanding, or do you disagree? If you disagree, please provide supporting evidence.
    
    9) Meyer claims:
    "If the IPCC is correct that based on their high-feedback models we should expect to see 3C of warming per doubling of CO2, looking backwards this means we should already have seen about 1.5C of CO2-driven warming based on past CO2 increases."
    More misinformation and oversimplification, see here. Or do you agree? If yes, please provide supporting evidence.
    
    10) Meyer claims:
    "Past warming has in fact been more consistent with low or even negative feedback assumptions."
    Really? Do you agree with that assertion? If yes, please provide supporting evidence.
    
    11) Meyer claims:
    "Skeptics point out that no one really has any idea of the magnitude of the cooling from these aerosols, and that, ironically, every global warming model just happens to assume exactly the amount of cooling from these aerosols that is needed to make their models match history"
    This is a gross exaggeration and misrepresentation of facts. Or do you agree with his claims? If yes, please provide supporting evidence.
    
    12) Meyer claims:
    "What they deny is the catastrophe — they argue that the theory of strong climate positive feedback is flawed, and is greatly exaggerating the amount of warming we will see from man-made CO2. "
    It seems from your comments above that you agree with this misguided and uninformed statement. No?
    
    IMHO, the premise of Meyer's argument is not based in reality and is certainly not a compelling case to delay or prevent taking action on reducing our GHG emissions. In short, he is a merchant of doubt. He (or anyone who supports his claims) is also betting against physics...and to do so is pure folly.
45. scaddenp at 11:28 AM on 23 February, 2012
    Albatross, this is one excellent dissection. Should be sent to Forbes.
46. GillianB at 11:31 AM on 23 February, 2012
    Why is the 'oft-cited 97%' always 97%? This figure comes up in a number of surveys of climate scientists.
    
    1) You link to a 2004 study showing 97% (link is broken btw).
    
    2) Doran and Zimmerman 2009 is quoted as showing 97% (this is the study famous for have a sample of only 79 climate scientists)
    
    3)William R. L. Anderegg, James W. Prall, Jacob Harold, and Stephen H. Schneider (April 9, 2010). "Expert credibility in climate change". Proceedings of the National Academy of Sciences of the United States of America.
    
    This found that 97–98% of the climate researchers most actively publishing in the field support the tenets of ACC (Anthropogenic Climate Change) outlined by the Intergovernmental Panel on Climate Change, and (ii) the relative climate expertise and scientific prominence of the researchers unconvinced of ACC are substantially below that of the convinced researchers.
    
    4) Stephen J. Farnsworth, S. Robert Lichter (October 27, 2011). "The Structure of Scientific Opinion on Climate Change". International Journal of Public Opinion Research. Retrieved December 2, 2011. This study of members of the American Geophysical Union or the American Meteorological Society found that 97% agreed that that global temperatures have risen over the past century. Moreover, 84% agreed that "human-induced greenhouse warming" is now occurring. Only 5% disagreed with the idea that human activity is a significant cause of global warming.
    
    The 97% figure is widely quoted and somewhat confusing because it is so closely linked with the Doran and Zimmerman study with the small sample. I'm curious that the number seems to have been reproduced so consistently.
    
    It's unusual in social research that a percentage across four studies using different methods and different samples would be exactly the same.
47. GillianB at 11:34 AM on 23 February, 2012
    Yes, I know...not quite 'exactly' the same.
    
    97-98% in one study
    95% among the meteorologists (taking the 5% who disagree that human activity is a significan cause)
    
    But still... this is an unusual level of uniformity.
    Moderator Response: [muoncounter] A more appropriate thread for this discussion is here.
48. william at 13:09 PM on 23 February, 2012
    The sudden jump in CO2 at the end of glacials may be due to Methane Clatrate (geologically speaking, instantly oxidized to Carbon dioxide) trapped under the ice sheets and released to start a run away green house effect as the ice started to melt from a Milankovitch nudge.
    http://mtkass.blogspot.com/2011/08/end-of-ice-ages.html
    
    Incidentally, New Scientist Feb4, 2012 p17 reports on some new work on the effect on wheat crops of climate warming. Not a pretty picture.
49. Bern at 13:16 PM on 23 February, 2012
    Gillian @ 47: it may just be that all of the studies are accurately reflecting the real proportions.
    
    william @ 48: Probably more from decaying organic matter in melting permafrost than clathrates, although outgassing from warming oceans would make a contribution too.
50. scaddenp at 13:18 PM on 23 February, 2012
    william, studies on YD would indicate no. eg Schaefer 2006
    
    You might also want to look for more recent work by Petrenko but I dont have a reference to hand.

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