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Comments 34251 to 34300:

  1. The 97% v the 3% – just how much global warming are humans causing?

    Tom Curtis @42

    The title of the article is, "The 97% v the 3% – just how much global warming are humans causing?". Leaving out 62% of the title, with no indication that you have done so represents misquotation, and in this case, out of context quotation to boot. Both are forms of dishonesty, and in academic situations are regarded as a type of academic fraud.

    Tom, I seem to have touched a nerve, but there was a method to my madness.  And yes, I take more care in an academic context compared to a comment on a blog.  However, I might truncate a title when discussing an actual academic paper within the confines of comments attached to that exact paper, assuming that if someone got that far, I'd think they would have read the title already.  And I don't think I'd be accused of "fraud".  Sloppy? Subjective. "Concise" would be my preference.  I could have just as easily left any portion of the title out (or all of it), and I think people would have got the gist. Haha.

    Tom Curtis @42

    More importantly, the 97% and the 3% are mentioned in the title and paper, but not discussed.

    I disagree. The author defined 3% of climate experts as believing a sub 50% anthropogenic attribution in the first paragraph of the article and referenced (at least on the newspaper page) Cook 2014 as the source of that figure.  If it were unimportant....

    So, who cares? Why am I picking nits?  I believe the IPCC consensus view and I believe strongly that we really need to be doing something about it.  But care needs to be excercised in communicating about it. Why? Because there's a strong danger similar to the "crying wolf" parable. Over-stating a case, and exaggerating the degree of consensus is potentially damaging in the effort to convince those who don't believe that CO2 is causing warming.  I think we need to be prepared for things like the "pause" continuing beyond this year. What if it winds up being 28 years? Or 40 years?  I personally think that's unlikely.  But it's going to be a tough sell made a lot harder by over-stating a case and then back-pedaling. Extreme caution needs to be exercised in delineating what is known and what is still in the theoretical realm.  But that's just my opinion.

    Tom Curtis @42

    If you wish to interpret the article as "The IPCC position vs a fringe consensus position" with the understanding that the arguments of those who don't make that fringe position are even worse than the poor arguments by Curry, I doubt Dana (or anybody else at SkS) will care. It is a non-issue.

    What I wish is pretty irrelevant, but if I were to be pinned down to characterize the Schmidt/Curry debate over attribution, I would say that Schmidt's position is Schmidt's position and Curry's is Curry's.  I don't think Gavin Schmidt would consider himself as speaking for the IPCC any more than Curry would think she is speaking for a larger fringe group.

  2. The 97% v the 3% – just how much global warming are humans causing?

    jwalsh @38:

    "As good as the outputs of the CMIP5 series of models are in providing much of the data for the AR5 graph in question, nobody considers them completely definitive. If that were the case, the over-prediction of temperature wouldn't be a current issue for the modelers. And it is."

    I do not think anybody is claiming the models are "definitive".  That is why the estimates have error margins.  Leaving aside the fact that the models are not the only basis of the attribution, the fact that error margins were shown, and then expanded to allow for uncertainties in the method shows that you are arguing against a strawman.  Further, you are arguing inconsistently in that you assume any increased uncertainty must reduce the percentage of the anthropogenic contribution, whereas it is equally likely to increase it.

  3. The 97% v the 3% – just how much global warming are humans causing?

    jwalsh @41:

    "But I'll try and stay on topic. The Topic of the article was "The 97% v. the 3%"."

    The title of the article is, "The 97% v the 3% – just how much global warming are humans causing?".  Leaving out 62% of the title, with no indication that you have done so represents misquotation, and in this case, out of context quotation to boot.  Both are forms of dishonesty, and in academic situations are regarded as a type of academic fraud.  I presume in your case they represent sloppy practise, however sloppy practise that gives an appearance of greater strength to your argument than actually exists.

    More importantly, the 97% and the 3% are mentioned in the title and paper, but not discussed.  Specifically, there is no discussion of what specifically divides the two groups, nor of how we know it, or even of the significance of the division.  Rather the terms "97%" and "3%" are merely used as labels, with the discussion in the article (and hence the topic of the article) restricted to the IPCC's attribution statements with particular regard to Fig 10.5.  The article could have easilly used labels such as "accepters" and "challengers" of the IPCC consensus, and it would have made no difference to the substance of (and hence the topic of) the article.

    As labels they are not ideal in this case, in that Curry does (barely) accept that 50% of recent warming has been anthropogenic with a very large error margin.  As such, she nominally falls inside the consensus position as categorized by Cook et al (and more directly relevant, Doran et al, 2009).  She is, however, clearly a challenger of the IPCC consensus position.  If you wish to interpret the article as "The IPCC position vs a fringe consensus position" with the understanding that the arguments of those who don't make that fringe position are even worse than the poor arguments by Curry, I doubt Dana (or anybody else at SkS) will care.  It is a non-issue.

    (I don't think that would be an accurate presentation, in that I don't think Curry's arguments and overall position are consistent with a genuine 50/50 position.  But whether it is accurate or not, it is irrelevant to the substance of the article.)

  4. Antarctica is gaining ice

    Oh, a final thought - sea ice and albedo is rather different between arctic and antarctica. Running the numbers can done and see here for one example.

  5. The 97% v the 3% – just how much global warming are humans causing?

    " Your distortions of Cook et al sugest that is not too unkind an assessment."

    I wish you'd pointed out how I distorted it (email me?). But I'll try and stay on topic.  The Topic of the article was "The 97% v. the 3%".

    But to avoid any distortions on my part. From the Cook paper. "Among abstracts that expressed a position on AGW, 97.1% endorsed the scientific consensus."  and "Among self-rated papers not expressing a position on AGW in the abstract, 53.8% were self-rated as endorsing the consensus."

    Category 2 of Explicit Endorsement in the Cook paper was defined as "Explicitly states humans are causing global warming or refers to anthropogenic global warming/climate change as a known fact"

    Curry is at least Category 2 by believing the anthropogenic component is roughly 50%. In fact, I'm uncertain what percent would qualify, but 50 should knock it out of the park! Heh.

    So, if Schmidt and Curry debate, it's really between two people within the 97%. If you want to hear from the 3% (and I am uncertain why you would, as defined), someone else needs to step up.  However, realistically Schmidt speaks for himself, and Curry speaks for herself.

  6. Antarctica is gaining ice

    And here are figures showing increasing temperature of the circum-antarctic ocean and its decreasing salinity.

    Source:

    Interesting paper, co-authored by Judith Curry, also noting the increasing sea temperatures here.

  7. The 97% v the 3% – just how much global warming are humans causing?

    jwalsh @39, the list of Bart Verheggen's articles is here, as found from the "Author's Posts" page.  The top two relate to Verheggen et al.  I note that there is every reason, when you are attempting to quantify the opinions of people in a certain group (scientists who have published in the peer reviewed literature on climate science) to not include an extraneious group who have not published in the peer reviewed literature on climate science solely because they hold a particular opinion on the topic.  Beyond that, your statistical manipulations bring to mind the saying about lies, damned lies and statistics ....  Your distortions of Cook et al sugest that is not too unkind an assessment.  Not to put to fine a point on it, the claim that the Cook et al categories measured "that at least part of the warming was man-made" is a lie; and one concocted after the initial reaction to the paper showed the "skeptics" to have interpreted the paper correctly, ie, a test of endorsement of the claim that 50% plus of recent warming was anthropogenic.  (I make no claim as to whether or not you are deliberately decieving, or merely hoodwinked.)

    I repeat, if you want to discuss the paper in detail, dicuss it where it is on topic.

  8. The 97% v the 3% – just how much global warming are humans causing?

    [quote]Verheggen et al increased their sample by including a group of AGW "skeptics" who would not otherwise have met the criteria. Further, many of the scientists surveyed are not expert in attribution, whether expertise is determined by relative number of papers, or by field of study. Therefore simplistic interpretations such as yours are not warranted. I am not going to go into it here, however, where it is off topic. If you want to discuss it in detail, there are several blog posts on this site in which Verheggen discusses the paper. They are most conveniently found by using the "author's posts" page under the "about" menu. [/quote]

    I am new to the site, and didn't see Verheggen as the author in the drop-down.

    I have read both Cook 2014 and Verheggen 2014 in entirety.

    And yes, Verheggen's paper included what was said to be 5% of respondents culled from those taking a contrary position. Which frankly concerned me when I read it. Applying multiple pre-selection criteria is another sort of potential bias.  And why wouldn't you include a spectrum of beliefs if you were trying to quantify that spectrum? Hmmm.... However, using back of napkin math, removing 5% of those thinking it's unknown or less than 50% brings it to roughly 70/30.  Still a far cry from 2-4%.  I noticed that the Cook 2014 study was the reference for 2-4%.  Under that study, the 97% figure was for those papers that were subjectively deemed to hold a position that at least part of the warming was man-made. And under that definition Curry is very much NOT a part of the "2-4%".  The majority of papers were deemed to not take a position in the abstract. Which leads one to speculate that the authors possibly did have an opinion, but you just couldn't tell from the abstract. Reading the full paper might be instructive in that case, or you could just ask them. Isn't that what Verheggen did?

  9. Antarctica is gaining ice

    Geothermal heat and ocean heat are both things that are measured. I pointed you to papers on both here and here. You seem to be simply ignoring measurements in those comments and going argument from Personal Incredulity and rhetoric ("Madagascar's beaches").

    "The overall combined total of southern and northern sea ice, is very high this year and last year, and therefore ice/water solar reflectivity is "on average, near it's recorded peak". Can you cite your reference for this please? Albedo change is related to summer ice extent so I am having some difficulty with this claim.

  10. The 97% v the 3% – just how much global warming are humans causing?

    As good as the outputs of the CMIP5 series of models are in providing much of the data for the AR5 graph in question, nobody considers them completely definitive. If that were the case, the over-prediction of temperature wouldn't be a current issue for the modelers. And it is.

     

    There will of course, be a CMIP6 series. In fact one of the stated goals of the CMIP6 project is " What are the origins and consequences of systematic model biases?"

    CMIP6 outputs will no doubt be part of AR6.  It will be interesting to see the differences.  But whether they are much improved will require additional decades of data to see.

  11. 2014 SkS Weekly Digest #37

    I've noticed that Tamino's Open Mind blog is inactive, with comments stopped. Anyone know if this is temporary or permanent, as Tamino has been a superior source of insights and information.

  12. The 97% v the 3% – just how much global warming are humans causing?

    jwalsh @16, before proceeding, I would like to introduce Fig 10.6, which shows estimates of the contributions of various factors on a purely empirical basis:

    Based of that chart, and using Folland (2013) as showing the lowest Anthro contribution, you can derive the following attribution estimates:

    Volcanoes 0.00%
    Solar -6.31%
    ENSO 10.81%
    AMO 0.00%
    Anthro 95.50%
    Nat -6.31%
    Int Var 10.81%

    I think those estimates overestimate the ENSO contribution by not using the SOI index, but that is neither here nor there.  The important thing here is that the estimates shown are well within the 1 sigma range for table 10.5.  Now, if you prefer to use a 95.5% anthro contribution rather than a 107.7%, that's fine by me.  But there is no justification for claiming that the IPCC estimates are solely model based, nor that rellying on emperical estimates will result in low estimates of the Anthro contribution.

    Turning now to your points:

    "But I fundamentally stand by my orginal assessment. The 10.5 graph was primarily derivative of a very small group of papers discussing model outputs."

    You can stand by it all you like, but the further reading of the IPCC report clearly shows that additional factors went into determining the Anthro contribution, and especially the Internal Variability contribution.  (Your claim is true in the restricted case of Greenhouse and OA).

    "My take was that the 10.5 graph was never intended to display the full picture of attribution, or theories behind it. And the considerable text in the section supports that view, rather than disproves it."

    Nobody is claiming that Fig 10.5 was intended to display the full picture.  It was, however, intended to display the simplest graphic summary of the IPCC findings, as is shown by the repeated citations of it in the Executive Summary.  Further, the Executive Summary states:

    "It is extremely likely that human activities caused more than half of the observed increase in GMST from 1951 to 2010. This assessment is supported by robust evidence from multiple studies using different methods. Observational uncertainty has been explored much more thoroughly than previously and the assessment now considers observations from the first decade of the 21st century and simulations from a new generation of climate models whose ability to simulate historical climate has improved in many respects relative to the previous generation of models considered in AR4. Uncertainties in forcings and in climate models’ temperature responses to individual forcings and difficulty in distinguishing the patterns of temperature response due to GHGs and other anthropogenic forcings prevent a more precise quantification of the temperature changes attributable to GHGs. {9.4.1, 9.5.3, 10.3.1, Figure 10.5, Table 10.1}"

    (Original emphasis.)

    Note that quoteing the less emphatic findings on greenhouse gas contribution is misleading because there is a higher uncertainty about the greenhouse gas contributions than about the total anthropogenic contributions as shown in Fig 10.5 and discussed extensively above.

    For what it is worth, based on Fig 10.5, the there is 90% confidence that greenhouse gases caused 54% or above warming, and 95% confidence that it caused 31% or above.  Clearly the statement you quote as proving a lack of reliance on Fig 10.5 shows no such thing.  There is more basis on the the section I quoted, with Fig 10.5 showing the 95% confidence ("extremely likely") at 79%, and 99% confidence ("virtually certain") at 67% contribution.  That, however, can be attributed to the IPCC's well known caution.

    Regardless, even the IPCC's "extremely unlikely" finding, together with both empirical and model based methods showing near 100% mean attribution shows that conclusions finding near 50% attribution are simply unwarranted.  They are the result of bias, not analysis (and very plainly so in the case of Curry).

    "Verheggen et al. 2014 asked a number of climate scientists to provide a figure for attribution ..."

    Verheggen et al increased their sample by including a group of AGW "skeptics" who would not otherwise have met the criteria.  Further, many of the scientists surveyed are not expert in attribution, whether expertise is determined by relative number of papers, or by field of study.  Therefore simplistic interpretations such as yours are not warranted.  I am not going to go into it here, however, where it is off topic.  If you want to discuss it in detail, there are several blog posts on this site in which Verheggen discusses the paper.  They are most conveniently found by using the "author's posts" page under the "about" menu.  

  13. Thousands of ‘Nameless Short-Lived Lakes’
    result of calculation in last sentence of my last post will be in mm and mm/yr
  14. Thousands of ‘Nameless Short-Lived Lakes’
    Mr sauerj: see fig 8 in Hansen(2012) "Paleoclimate ..." linked to by Mr. M. A. Rodger at 1:50 AM 14 sep 2014. Then divide y axis by 360.
  15. The 97% v the 3% – just how much global warming are humans causing?

    Rob Honeycutt @25, certainty about the strength of radiative forcing does not translate directly into certainty about the relative temperature response, both because of uncertainty about climate sensitivity and uncertainty about relative effectiveness of different radiative forcings.  Further, Russ R's point is about the relative uncertainty of Anthro, Greenhouse and OA as shown on fig 10.5.  His point is invalid, but I have to agree with him that the figure you show is irrelevant to the discussion.

    Further, if it were relevant it would support his case as the uncertainty of all anthropogenic forcings is significantly larger than the uncertainty of any individual element, and likely larger (and at least comparable in size to) the uncertainty of Greenhouse radiative forcing or OA radiative forcing.

  16. The 97% v the 3% – just how much global warming are humans causing?

    Russ R @various:

    1)  The formula  combining uncertainties on addition is:

    σA2=σx2+σy2+2*ρ*σx*σy,

    where σA is the uncertainty of the combined term, while σx and σy are the uncertainties of of the two terms summed to derive the combined term.  In this particular case, that means we can treat σA as the uncertainty of Anthro, and σx and σy as the uncertainties of Greenhouse and OA respectively.  This had already been explained to you in words by Bob Loblaw (@9 and 10), and the base formula from which (together with definitions) the above can be derived had been given to you by Kevin C (@19).  It should be noted that the formula can be used for any level of uncertainty, not just one standard deviation (1 sigma), provided the same level of uncertainty is used for each term.  It should also be noted that the formula assumes the distribution of uncertainty is normal (I believe).)

    2)  It has already been noted in discussion above by J Walsh (@13) that the relative uncertainties for Greenhouse and OA are derived from the model ensemble, scaled to the observed warming (as noted by me @15); and the graph representing the relevant values presented by me (also @15).  From this, simple visual inspection will show the clear anticorrelation of Greenhouse and OA.  Further, simple visual inspection of column C will show the very low variance of Anthro.  What is more, the logical reason for this relationship has been mentioned to you several times by different respondents, including by me in my second pont @2.  As I predicted @7, your entire discussion since has simply been a process of ignoring the information already presented you in the second comment on this thread. 

    3) Anthro is not only constrained by the relationship Anthro = Greenhouse + OA, but also by the relationship Anthro = Obs - (Nat + Internal Variability).  Therefore its uncertainty is more tightly constrained than the constraints of just Greenhouse and OA.  That allows its uncertainty to be tighter than it would be if calculated from just those two.  It also allows other information in addition to scaled relative contributions in the model ensemble to enter determining the values of Anthro, as discussed above @15.

    4)  For the sake of argument, if we allow the (known to be false) assumption that the uncertainty of Anthro was constrained by Greenhouse and OA alone, we can then calculate a derived uncertainty using the relationships between Greenhouse and OA shown on Figure 10.4.  They in fact show a correlation of -0.92.  Consequently, the "very likely" uncertainty range for Anthro would be 0.16 C.  However, the IPCC then relaxed that estimated uncertainty from a "very likely" to a "likely" range.  Therefore the strict and pedestrian calculation on the basis that you suggest would have resulted in a tighter "likely" range than is shown in Fig 10.5, not a broader range, and indeed would have required a "likely" range less than +/-0.08 C.

    5)  Even if we allow the (known to be false) assumption that the uncertainty of Anthro was constrained by Greenhouse and OA alone, and still follow the IPCC in dropping "very likely" to "likely" ranges, that would still only result in an "likely" range of +/- 0.16 C, and a less than 1% chance of the Anthro contribution being less than 50%.

    Your horse is dead, and already flogged into a bloody ruin.  Will you cease floging it.

  17. Antarctica is gaining ice

    jetfuel...  Can you please provide sources for these?

  18. Antarctica is gaining ice

    Two arguments support growth of Antarctic sea ice which hit 19.7M sq km Sept 14th. One is the loss of Arctic ice has exposed the ocean surface there to release more heat than previously. When it was covered with ice, it's ability to give off heat was less. The second argument is that the increased ice covered area at the southern polar region is reflecting more of the sun's energy than ever before. These same two arguments can be used in reverse: The Antarctic ice area is covering more sea water than ever and allowing it to retain it's heat, and at the Arctic, the less than average amount of sea ice is reducing reflectivity of the sun's energy. The overall combined total of southern and northern sea ice, is very high this year and last year, and therefore ice/water solar reflectivity is on average, near it's recorded peak. With the Arctic sea ice looking like it will not dip below 5M sq km this summer, there will be an increase again in multiyear ice there.

    The recent articles I've read downplaying this record Antarctic sea ice are using what happened in 2012 as the overriding factor. Right now, the sea ice ring around Antarctica is now an average of 750 miles in width, and is actually widest and most massive at the Ross Ice Shelf. The Ross Ice Shelf is noted in 2012 as being in danger of dissipating to unleash the West Antarctic Ice Sheet into the Ross Sea. For warm water today to flow under nearly 1000 miles of sea ice, then enter the Ross Sea, and then traverse through a thin water layer area the size of Texas, under a km thick of ice, then still be warm enough to melt the underside of a 2000 foot thick glacier's edge? I would be more inclined to believe the heat source is the Earth's core, not warm ocean water from Madagascar's beaches that has made that arduous journey described above.

  19. The 97% v the 3% – just how much global warming are humans causing?

    Russ... Responding to your comments on what we know and don't know that we don't know (or whatever):

    That is the whole point to constraining uncertainties. There is always some possibility that there is something out there on the fringes that's having an unknown influence, but given the large amount that is known on a wide range of factors, what's left that could have a significant influence becomes highly improbable.

  20. The 97% v the 3% – just how much global warming are humans causing?

    Russ R. - Actually, what you are saying, what you are claiming, is that the IPCC stated uncertainties for natural forcings, for internal variation, and/or for observations are wrong. 

    I await your references refuting the IPCC AR5 summaries on these matters. In the meantime, well, you are just arguing by assertion. IMO such arguments do not stand in the face of the evidence. 

  21. The 97% v the 3% – just how much global warming are humans causing?

    Russ... I'm not questioning your figure of ±0.4°C (which is why I didn't quote it), I'm challenging your interpretation of it. Again, the IPCC clearly states that GHG forcing has a high and very high level of certainty on these.

  22. The 97% v the 3% – just how much global warming are humans causing?

    Rob,

    You can keep arguing, or you can admit that I quantified (correctly) the amount of uncertainty as ±0.4°C.  

    You chose to omit that detail in your attempt to argue against me.

    Was I wrong or not?

    Awaiting your apology.

    Moderator Response:

    [JH] Please keep it civil.

  23. The 97% v the 3% – just how much global warming are humans causing?

    No KR,

    I'm saying we know what we know, and that we don't know how much we don't know.

    But we don't know all there is to know.  And only by presuming that we know all there is to know can we claim that the uncertainty of the remainder is low.

  24. The 97% v the 3% – just how much global warming are humans causing?

    Russ R. - You did, I assume, also note the uncertainties on natural forcings and on internal climate variability? Which are each +/- 0.1°C? And the uncertainties on observations, +/- 0.05°C?

    Again, the total forcing is well known, so are the natural and internal variation forcings - meaning that the higher uncertainties in GHGs and other anthropogenic forcings are indeed negatively correlated.

    1+1+G+A=4, G+A=2. It's really that simple. As Rob points out, you appear to be invoking little green men - claiming that we must not know what we know. 

  25. The 97% v the 3% – just how much global warming are humans causing?

    Russ...  You state "We only know GHG to a low level of certainty" [my emphasis] and the far left column of the radiative forcing chart clearly states that we have a "H" (high) or "VH" (very high) level of certainty for well mixed greenhouse gases, which clearly make up the dominant forcing.

  26. The 97% v the 3% – just how much global warming are humans causing?

    Rob Honeycutt @ 26:

    You misquoted me by leaving out the quantity.  

    ""But what we actually do know about ANT directly is far more uncertain. We only know GHG to a low level of certainty..."

    Hm. Actually, I believe that is wrong...

    What I actually wrote:

    "We only know GHG to a low level of certainty (±0.4°C),"

    Which is exactly the value in the IPCC's chart above, and is a low level of certainty relative to the ±0.2°C claimed for total ANT.

    Still believe I'm wrong?

  27. 97 hours of consensus: caricatures and quotes from 97 scientists

    @ Tom Curtis at 10:58 AM on 16 September, 2014

    It is not my claim that calibrations can be performed by laymen. One point I tried to make was that properly presented test result can be easy to comprehend even if the model is complex and that properly presented data are strong arguments.

  28. The 97% v the 3% – just how much global warming are humans causing?

    Russ R...  What I'd suggest here is that, in order to work, the argument you're putting forth here would require a yet unknown mechanism that un-explains the high level of certainty that we have about greenhouse gases, and adds a yet-so-far completely unknown forcing to take its place.

  29. The 97% v the 3% – just how much global warming are humans causing?

    Russ R. said @24... "But what we actually do know about ANT directly is far more uncertain. We only know GHG to a low level of certainty..."

    Hm. Actually, I believe that is wrong. We have a high to very high level of scientific understand about the radiative forcing of anthropogenic greenhouse gases:

  30. The 97% v the 3% – just how much global warming are humans causing?

    KR,

    Your comment relates to the concept that OBS - (NAT + INT) = ANT.  (In other words, anything we can't explain must be anthropogenic.)

    Yes, observed warming has very little uncertainty, and the warming ascribed to NAT and INT is claimed to be quite certain (±0.1°C), but is unfortunately limited to the extent of our knowledge of those processes (which is turning out to be more uncertain than previously thought).  It's necessarily a case where we simply don't know how much we don't know.

    But what we actually do know about ANT directly is far more uncertain.  We only know GHG to a low level of certainty (±0.4°C), and know virtually nothing about OA except to say that it is equal to ANT - GHG.

    But to say that we know ANT to a high level of certainty (±0.2ºC) is only possible if we assume that we know everything about NAT and INT with high certainty.  Which is the same as assuming a high level of certainty of ANT.

    And we can't simply assume that the uncertainty of the components (GHG & OA) is negatively correlated because the uncertainty of ANT is assumed to be low.

    Circular reasoning works because circular work.

  31. 97 hours of consensus: caricatures and quotes from 97 scientists

    @ Tom Curtis at 10:58 AM on 16 September, 2014

    You are right, my premise were false, my assertion was wrong, it is not correct to say that: "Very many are trained through education and profession to recognize and disregard arguments containing logical fallacies."

    Thank you for your response to my false assertion.

  32. The 97% v the 3% – just how much global warming are humans causing?

    Anyone got more information about the 3%?

    I know a lot of careful work has gone into nailing down the 97% number and those who have been working on this are deserving of praise.

    But that statistic on its own isn't enough.

    3% doesn't seem that low to those who imagine that good science is only done by a minority of scientists - a few Gallileos!

    Many will see this 3% as a crack in the edifice of Climate science: a chink of light in the darkness that is the future as foretold by those gloomy lefty boffin-heads!

    3% isn't so tiny. Sure doesn't 1% of population of USA own 35% of all the wealth. Maybe in the same way 3% of climate scientists have 50% of the knowledge.

    What is needed, I think, is an analysis showing that this minority is diminishing, becoming obsolete, that their work has been shown to be flawed, that their findings have been refuted and that many of them have been discredited by their continued use of already refuted arguments...etc.

    What is needed is the extinction of that kind of stupid optimism that allows people to continue in vast numbers to entertain the notion that there is a chance - an outside chance - that maybe - just maybe - this climate change stuff is nonsense. Because that is what people do. For the reckless, the miserable and the desperate, 3% isn't such a bad gamble! It's a light in the darkness!

    Extinguish it!

    Anyone working on this?

  33. The 97% v the 3% – just how much global warming are humans causing?

    Russ - See my comment here [which you have not responded to]. The sum of forcings is strongly constrained by other data such as OHC, hence component forcings with larger uncertainties are by necessity negatively correlated. If one is underestimated, other(s) (under the constraints on totals) must be overestimated. 

  34. The 97% v the 3% – just how much global warming are humans causing?

    Kevin C.

    Thank you, I get it... the variance of whole is less than the variance of the parts when the covariance is negative.

    To accept an uncertainty of ANT of only ±0.2ºC, when the uncertainties of GHG and OA are ±0.4°C and ±0.35°C respectively, you must necessarily believe that the covariance is negative.

    Got any actual evidence to make any type of valid estimate of the covariance of the error terms for GHG and OA?  Or shall we just assume that it's negative?

  35. The 97% v the 3% – just how much global warming are humans causing?

    Russ @18, why does your quoted section begin halfway through a sentence?

  36. The 97% v the 3% – just how much global warming are humans causing?

    Russ:

    var(x+y) = var(x) + var(y) + 2 cov(x,y)

    var(x-y) = var(x) + var(y) - 2 cov(x,y)

    Covariance can be positive or negative. So the variance of either the sum or the difference between two variables can be smaller than the variance of either.

    Take the trivial case y=-x. Then x+y=0 by identify. Since cov(x,y) = cov(x,-x)=-var(x), var(x+y)=0, which is necessarily true.

  37. The 97% v the 3% – just how much global warming are humans causing?

    Thank you Bob Loblaw and Tom Curtis,

    "the combined error would be +/-0.53 C for the "likely" range. That would allow a 17.3% chance of 50% or less anthropogenic contribution"

    This is exactly what I was getting at, and it's a whole lot different from the PDF shown above which states that "the probability of the human contribution being less than 50% is almost nil"  or in Gavin Schmidt's words "p < 0.0001".

    The point I'm making (and I don't actually care if you don't like the roundabout way I'm making it), is that the PDF shown above uses an uncertainty estimate (±0.2ºC) that is far too low for anthropogenic warming because it's not acutally derived from any calculation of the components anthropogenic warming (i.e. ANT = GHG + OA). 

    Instead, the uncertainties show that the derivation is actually OA = ANT-GHG, (meaning OA is a plug figure).  And ANT is simply assumed to be the difference between OBS and (NAT + INT), where NAT and INT themselves are only estimated "to the best of our knowledge".  (As an aside, I find it interesting that the amount of variability being assigned to NAT and INT appears to be rising in an apparent attempt to explain away the recent lack of warming).

    To summarize, my argument here is that the uncertainty figure to use for anthro warming must be derived from what we can actually attribute to the components of anthro warming (GHG + OA), not what we assume must be anthro because we don't know how else to explain it.  I think that's called "begging the question".

    Moderator Response:

    [JH] Please keep it civil. 

  38. The 97% v the 3% – just how much global warming are humans causing?

    Bob,

    from 10; It is my understanding that the correlation is negative.  The Anthro contribution is well measured.  When it is split into the Greeenhouse and other contributions, there is a large uncertainty about aerosols.  This shows up in both distributions.  They must add to the Anthro contribution so if aerosols have a large negative contribution the greenhouse must be bigger.  If aerosols have a small contribution the greenhouse must be smaller.  The aerosol cannot be large negative and the greenhouse small positive at the same time or they would not add together properly.  This makes the error smaller for net anthro.

  39. The 97% v the 3% – just how much global warming are humans causing?

    " it would be nice if you in fact let the IPCC explain, rather than cutting them of in mid explanation. "

    Of course I didn't post the whole passage. I assumed you all knew where to find it! :)

    Yes, it goes on into further detail.  But I fundamentally stand by my orginal assessment. The 10.5 graph was primarily derivative of a very small group of papers discussing model outputs.  Therefore, I think a statement like "The green bar shows the amount of warming caused by human greenhouse gas emissions during that time." is potentially misleading. The green bar is derived from climate model outputs.  And that may indeed be dead accurate, but if you think so, then you think they underlying models are. And that's a subject of debate.  The best way to gauge a model is by predictive ability, either forwards or backwards. And even with strong correlation it's not possible to eliminate coincidence as a possibility, except over increasingly long terms.

    My take was that the 10.5 graph was [b]never intended[/b] to display the full picture of attribution, or theories behind it.  And the considerable text in the section supports that view, rather than disproves it.

    And I don't think "while Judith Curry from Georgia Tech represented the opinions of 2–4% of climate experts that we could be responsible for less than half of that warming." is well supported by evidence, or the IPCC here.  In the same section, they go on to say that..

    "We conclude, consistent with Hegerl et al. (2007b), that more than half of the observed increase in GMST from 1951 to 2010 is very likely due to the observed anthropogenic increase in GHG concentrations"

    Very Likely, in IPCC parlance, is 90-100%.  And that's if you agree with their conclusions there. And not every climate scientist does.  But I certainly wouldn't want anyone to take my word for it. Verheggen et al. 2014 asked a number of climate scientists to provide a figure for attribution and roughly 2/3 rds reported above 50% anthropogenic.  The remainder either less or uncertain.  Setting aside method criticisms for the paper itself (close enough for this purpose), how does one reconcile this to the 2-4% estimate?  For that matter, where does 2-4% come from? Not from any study I have read.  Were too many climate scientists unaware of the CMIP5 and other model(s) results? 

    Moderator Response:

    [JH] Please keep it civil.

  40. The 97% v the 3% – just how much global warming are humans causing?

    jwalsh @13, it would be nice if you in fact let the IPCC explain, rather than cutting them of in mid explanation.  

    To start with, as shown in Fig 10.4 below, the models are used to determine relative contribution but are scaled to match actual temperature increases.  Thus if a model shows an anthropogenic temperature increase of 0.8 C, and a total increase of 0.7 C, then the anthropogenic increase is scaled by 0.65/0.7 to determine the anthropogenic contribution.  Thus any tendency to over estimate the temperature trend is eliminated as a factor in determining attribution.  All that remains is the relative responsiveness to particular forcings.  With respect to that, it is well known that the combined natural forcings from 1951-2010 are slightly negative, or neutral at best.

    Further, as the IPCC says:

    "We moderate our likelihood assessment and report likely ranges rather than the very likely ranges directly implied by these studies in order to account for residual sources of uncertainty including sensitivity to EOF truncation and analysis period (e.g., Ribes and Terray, 2013)."

    That is, they multiplied uncertainty by a factor of 1.36, thus substantially expanding the uncertainty range to account for any additional uncertainty relating to the methods used.  The models, note, only over estimate recent temperature trends by 18%, half the expansion of the uncertainty range - and that overestimation has been eliminated from the attribution by scaling in any event.

    Finaly, they go on to say:

    "The assessment is supported additionally by a complementary analysis in which the parameters of an Earth System Model of Intermediate Complexity (EMIC) were constrained using observations of near-surface temperature and ocean heat content, as well as prior information on the magnitudes of forcings, and which concluded that GHGs have caused 0.6°C to 1.1°C (5 to 95% uncertainty) warming since the mid-20th century (Huber and Knutti, 2011); an analysis by Wigley and Santer (2013), who used an energy balance model and RF and climate sensitivity estimates from AR4, and they concluded that there was about a 93% chance that GHGs caused a warming greater than observed over the 1950–2005 period; and earlier detection and attribution studies assessed in the AR4 (Hegerl et al., 2007b)."

    Thus while assessment of the relative contributions of Greenhouse and OA are restricted to the studies shown in Fig 10.4, the assessement of Anthro is not.  Indeed, they go on for an additional two paragraphs citing other factors which influenced the determination of the Anthro contribution as portrayed in fig 10.5, and still further discussion calling on a host of further studies relating to the role of Internal variability (which unlike forcings, which will scale alike, thus preserving relative contribution, may have been an issue).  They conclude that discussion by saying, 

    "To summarize, recent studies using spatial features of observed temperature variations to separate AMO variability from externally forced changes find that detection of external influence on global temperatures is not compromised by accounting for AMO-congruent variability (high confidence). There remains some uncertainty about how much decadal variability of GMST that is attributed to AMO in some studies is actually related to forcing, notably from aerosols. There is agreement among studies that the contribution of the AMO to global warming since 1951 is very small (considerably less than 0.1°C; see also Figure 10.6) and given that observed warming since 1951 is very large compared to climate model estimates of internal variability (Section 10.3.1.1.2), which are assessed to be adequate at global scale (Section 9.5.3.1), we conclude that it is virtually certain that internal variability alone cannot account for the observed global warming since 1951."

    Consequently, your attempt to paint the attributions shown in Fig 10.5 as exclusively model bases seriously misrepresents the IPCC - a misrespresentation sustained by quotation out of context.  Further, the attempt to portray an disagreement between model and observed trends ignores directly relevant factors by which the IPCC took that discrepancy into account.

  41. One Planet Only Forever at 13:52 PM on 16 September 2014
    2014 Arctic Sea Ice Extent Prediction

    franklefkin,

    5.35 will be very close, but is likely to be a little high.

    The NSIDC interactive chart (here) shows the following Arctic 2014 ice extents (for the area with 15% or more sea ice):

    • September 1: 5.579 million
    • September 12: 5.140 million
    • September 13: 5.108 million
    • September 14: 5.086 million

    So, with the ice extent likely to continue to decline a few days past the middle of September, the September average is very likely to be lower than 5.35. It may even be lower than 5.2.

    Also, the September 14th extent is lower than the minimum 2013 extent (5.101). So 2014 is already the 5th lowest minimum extent in the record. But it is unlikely to reach 4th place (4.626 - September 22, 2010).

  42. The 97% v the 3% – just how much global warming are humans causing?

    jwalsh - I think you are making a number of incorrect assumptions here. Firstly, as to why attribution is done with a model, then please see here. Whether ensemble model mean over or underpredicted surface temperatures is a different question from attribution. For instance, see Gavin Schmidt's response here.

  43. The 97% v the 3% – just how much global warming are humans causing?

    I am uncertain why there is the focus on Figure 10.5 from IPCC AR5.  Not even the IPCC, years ago,  considered that representative of all areas of climate science.  10.5 is derived from 10.4 which is derived from....  Well may as well let the IPCC explain.

    "The results of multiple regression analyses of observed temperature
    changes onto the simulated responses to GHG, other anthropogenic and natural forcings are shown in Figure 10.4 (Gillett et al., 2013;
    Jones et al., 2013; Ribes and Terray, 2013)."

    The papers referenced (3 in total) are based on climate models, and observations from them.  The extent to which anyone (including the IPCC) considers that a true picture of attribution, relies on the extent of belief in the accuracy of the model ensembles. And everyone knows there are problems there. Even the author of one of those papers authored another, "Overestimated global warming over the past 20 years" acknowledging observed model discrepencies. Numerous theories abound about why the models were inaccurate, but there is almost universal agreement that they were inaccurate.  I have no idea why. Not my field. In fact, I think it's safe to say that nobody knows yet. Models, as expected, are going to continually be refined and get better and better. 

  44. Thousands of ‘Nameless Short-Lived Lakes’

    Request: Could someone post two sets of curves here? This would be a good reference visual aid for sharing purposes.

    Set 1) Rate of SLR (Greenland contribution) vs year (2000 thru ~2120) in mm/yr; A family of 3 curves with doubling periods of 5, 10 and 12 years.

    Set 2) Accumulated SLR (integration of above) (GL contrib) vs year (same). With same 3 doubling period curves. ... thanks in advance, sauerj

    Moderator Response:

    [ps] sentence fixed as requested.

  45. The 97% v the 3% – just how much global warming are humans causing?

    Dana, small typo in the Gaurdian version (not included in the excerpt above):

    "Recent research led my by Michael Mann has..."

  46. The 97% v the 3% – just how much global warming are humans causing?

    Just out of general interest, if Russ R's supposition of independent errors for Greenhouse and OA were correct (and allow me to underline again, it is not), then the combined error would be +/-0.53 C for the "likely" range.  That would allow a 17.3% chance of 50% or less anthropogenic contribution, but also a 17.3% chance of a 150% or more contribution.  If that were the case, then there is a better than 1 in six chance that when natural factors equalize out in the long term (which is more or less inevitable, and certainly so for internal variations), we will be facing 50% greater than IPCC expected warming.  That is, there will be a one in six chance that strategies to keep warming under 2 C would result in a rise in GMST of 3 C.  As harm increases approximately exponentially with increased temperature, that makes the task of tackling global warming more urgent, not less.

    Fortunately we are not facing that bad new situation.  Also unfortunately, Russ R will not recognize that as a bad news situation because for him only the low side of the uncertainty equation is meaningfull (=usefull rhetorically).

  47. The 97% v the 3% – just how much global warming are humans causing?

    An addendum: when referring to 100% correlation above, I mean 100% positive. If the correlation is negative (i.e., one error being positive means the other error is negative, i.e., covariance is negative), then the error in A+B will be less than the error in either A or B alone.

  48. The 97% v the 3% – just how much global warming are humans causing?

    RussR:

    Your addition of ±0.4°C and ±0.35°C to get ±0.75°C is only correct if the two variables are 100% correlated in their fluctuations. This is highly unlikely.

    If the two errors are independent (0% correlation), then the correct way to add the errors is the root-sum-square approach:

    (0.4)2 + (0.35)2 = 0.532

    ...so the error in the sum (or difference) is ±0.53°C

    For correlations between 0 and 100%, you use the covariance to adjust between 0.53 and 0.75.

    Basic propagation of uncertainty in mathematics. I'm surprised you're not familiar with it.

  49. The 97% v the 3% – just how much global warming are humans causing?

    Russ R. - Because the sum forcings are more tightly constrained than the individual components. If natural forcings are in reality higher than estimated, then anthro forcings are lower, and vice versa. 

    This is similar to the case with estimates of top of atmosphere (TOA) imbalances, individual components of evaporative, convective, etc. in the Earth energy budget. Uncertainties on each component may be+/-10 W/m2, while the total Earth imbalance over the last 50 years from ocean heat content (OHC) is +/- a fraction of a Watt. Because the values for the total are established from different evidence than the values for any one of the components. 

  50. 97 hours of consensus: caricatures and quotes from 97 scientists

    dhf @51, you have been caught out arguing from a clearly false premise, whose only support has been your mere assertion.  It would be nice of you to acknowledge that your premise was in fact false, and has now been comprehensively refuted.  Merely picking an isolated sentence as a bridge to an urelated rhetorical sally is evasive and shows further discussion with you to probably be unfruitful.

    For what it is worth, while testing calibration is a useful test on theories, it often involves subtleties that require expert knowledge to understand, and hence it is not true that layman can check calibrations without detailed research.  In particular, the nearest analog of "calibration" in climate science is validation of models, which is a very complex subject.  In particular, it involves assessing the interplay of probabilities of multiple factors which are not independent; the ability to assess the significance of scale issues; and the ability to assess the relevance of timing of short term variable events such as ENSO (which because chaotic, can be reproduced statistically in models, but not with regard to exact timing and magnitude of particular events). 

    The denier strategy has been to simplify that complexity by focusing on just one variable (GMST) over a cherry picked interval (typically 1998 forward) and to declare the "instruments" to have failed because GMST almost drops out of the uncertainty range.  They frequently claim that it has dropped out of the uncertainty range by treating 1998 (which almost exceeded the uncertainty range) as a mean value thereby offseting the temperatures relative to model predictions.

    Further, nearly all of the purported model/observation discrepancy on GMST vanishes if models are contrained (either by selection or by constrained responses in the ENSO region) to match actual ENSO fluctuations.  That is easilly demonstrable by a number of means, the simplest of which is simply taking trends of La Nina, neutral, and El Nino years seperately; and hence should not be subject to dispute.  AGW deniers, however, simply ignore it as a factor in an approach best described as dishonest.

    These approachs are not scientific. They are pseudo-scientific.

    They are also not on topic on this thread.

    What is on topic is your apparent claim that these "calibrations" can be easilly performed by laymen, but apparently have escaped the experts notice.  Sorry, I see no point in debating such absurdities.

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