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Comments 44701 to 44750:

  1. New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made

    With all this discussion of the problems caused by Humlum et al's analysis that differentiates the data first, I am reminded of a math joke told to me years ago by a mathematician friend. (Yes, I know. "math joke" is an oxymoron. Don't ask me to tell you the one about Noah and the snakes.)

    Two mathematicians are in a bar, arguing about the general math knowledge of the masses. They end up deciding to settle the issue by seeing if the waitress can answer a math question. While mathematician A is in the bathroom, mathematician B corners the waitress and tells her that when his friend asks her a question, she should answer "one half X squared". A little later, when the waitress returns to the table, A asks her "what is the integral of X?". She answers as instructed, and mathematician A sheepishly pays off the bet and admits that B was right. As the waitress walks away, she is heard to mutter "pair of idiots. It's one-half X squared, plus a constant".

    [I'm not sure how much of the joke is a dig at mathematicians who forget some of the basics (the constant), or a dig that mathematicians can only find jobs working as a waitress in a bar.]

    But, back to the issue at hand - differentiation will take any constant term and turn it into zero. But to take the flux data and turn in back into a change in storage you have to integrate. And when you integrate, you are in deep, deep trouble if you forget the constant, which is what Humlum et al appear to have done. If you can't figure out what the constant is, then you can't figure out the numerical value of the integration.

    Details. Details.

  2. Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    Chordotonal: You most recent post was sloganeering and was therefore deleted. Please read the Comments Policy and adhere to it. 

  3. Dikran Marsupial at 04:11 AM on 8 June 2013
    The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.

    KR testing the sensitivity of the analysis to the choice of AMO definition would indeed be a good thing, however they would all be susceptible to the problem of contamination with anthropogenic and natural forcings, and hence the resulting attribution will still be at best questionable.

  4. The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.

    robert way - While there are many ways to calculate the AMO, I would disagree about Anderson et al 2012 being ad hoc; they are using PCA to estimate the anthro versus natural variation components; they have numeric support for their position. And they agree with the Trenberth and Shea 2006 method. 

    Regardless - Any comparison of Dr. Tungs technique against different AMO estimations would provide a sensitivity analysis for those variations in AMO definition. Dr. Tung has not performed such a check - and until/unless he does, I do not feel his conclusions stand given the various counterexamples of colinearity contamination discussed on these threads. 

  5. New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made


    I thought the BEST group of physicists had proved once and for all that all global warming in last 250 years can be accounted for by volcanism and the log of CO2 concentration.
    Rohde, R., Muller, R. A., Jacobsen, R., Muller, E., Perlmutter, S., Rosenfeld, A., Wurtele, J., Groom, D. and Wickham, C.: A new estimate of the average earth surface land temperature spanning 1753 to 2011, Geoinfor Geostat: An Overview, 1, 1, 7pp, doi: 10.4172/gigs.1000101, 2012.
    This is consistent with the physics. The greenhouse gas is active in the upper stratosphere/troposphere boundary. To solar radiation Earth looks like a bubble. This bubble traps the heat. It is dependent on CO2 rather than water vapour that does not reach so high. Rohde et al., (2012) is consistent with this and explains all the temperature changes observed. What goes on inside the bubble affects that surface. Most of the surface is saltwater.
    There is s similar boundary layer in the upper ocean that traps heat. According to Levitus et al., (2012) ocean heat accounts for 93% of anthropogenic global warming.
    Levitus, S., Antonov, J. I., Boyer, T. P., Baranova, O. K., Garcia, H. E., Locarnini, R. A., Mishonov, A. V., Reagan, J. R., Seidov, D., Yarosh, E. S. and Zweng, M. M.: World ocean heat content and thermostatic sea level change (0–2000 m), 1955–2010, Geophys. Res. Lett, 39, L10603, 5pp, doi: 10.1029/2012GL051106, 2012.
    Data from oceans is sparse at best with 1 degree lat and long coverage averaged over upper 100m only available since 1990s. What is needed is far better data on the 93% heat and rather less statistics on the 7%.
    Unfortunately this requires going to sea and making actual measurements. It is timeseries of near-surface temperature and salinity data that holds the key. These are not available from satellites. Computer models are only as good as the field verification data. There are huge tracts of ocean for which data is lacking including the Pacific and the Arctic.
    In my opinion it is time for a concerted effort to go to sea and get the data. It can only confirm what Rohde et al., (2012) showed - CO2 concentration is the principal driver of global warming; and confirm Levitus et al., that 93% of that is in the oceans.

  6. The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.

    "KR I would strongly suggest theTrenberth Shea 2006 methodology, supported by Anderson et al 2012, as one detrending methodology worth considering."

    KR,
    I disagree. All these ad-hoc methods of calculating the AMO are not rationalized and if you read the article I listed before you will see that these variants of the AMO ALL struggle when it comes to deciphering the proper signal. Personally I use two versions and compare the results of each. One is the detrended first component of North Atlantic SSTs and the other is the Van Oldenborgh et al, 2009. They're both wrong but I believe that reality lies between the two. Once again reading that previous study I linked to here:

    http://link.springer.com/content/pdf/10.1007%2Fs00382-013-1669-0.pdf

    Should be read by everyone while discussing this issue.

  7. CO2 increase is natural, not human-caused

    Thanks for the answers and sorry for the double-post, no idea how that happened.

    Moderator Response:

    [Dikran Marsupial] no problem, easily fixed.

  8. Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    Chordotonal, Lu has been riding this pony for a while.  He's received published feedback on it.  He's ignored it (look at the links at the bottom of the main article).  When does it get real?  

  9. New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made

    reality, I'll be happy to discuss "climategate" with you on the appropriate thread.  I'm professionally interested in what you learned from "climategate."

  10. Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    "The problem all along has been his lack of providing the necessary mechanics to support that fitting. Should that be the basic requirement for publication?"

    If you are saying he needs a good apriori case yes I agree. If you are saying that he does not have one, yes I agree with that also.  But we ought not get too precious about publication.  So we are saying he has a good one-shot correlation but he doesn't have a good apriori case.  So its just a matter of making a start on an hypothesis that is likely going to wind up failing for lack of convergent evidence.  We ought not be treating him as some sort of heretic, since this is how you go about proving things. 

    Moderator Response:

    [JH] You are skating on the thin ice of sloganeering and excessive repitition -- both of which are banned by the SkS Comments Policy. Please read the Comments Policy and adhere to it. Thank you.     

  11. Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    Chordotonal, where did this become about Lu's basic use of curve-fitting.  The problem all along has been his lack of providing the necessary mechanics to support that fitting.  Should that be the basic requirement for publication? If so, Willis Eschenbach just smiled. The number of pedal strokes I used to get to work this morning was exactly the same as the number of strokes used by Paris Hilton to comb her hair this morning. I say the two are causally related. It has to do with the . . . ummm . . . gravitational resonance from the friction in my bottom bracket. The frequency of the resonance matches Hilton's brain structure, causing the repetitive motion at just the right time. What? She combs her hair every morning, even when I'm not riding my bike? Not listening! Not listening! I'll be publishing soon in Journal of Auras and Dweomers.

    In a world where rapid global warming is not an issue, does Lu repeat and publish the analysis?  SkS is also about the communication of climate science, and Lu's garbage looks like gold to the paid misinformers of the general public.  If you perform poor science and then try to get it published, knowing that it will be used to confuse the general democracy . . . what's up with that?

  12. Dikran Marsupial at 01:14 AM on 8 June 2013
    Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    (-snip-).

    A word of advice, you have now posted argumentative messages on several threads.  This is usually a sign of drive-by trolling, becuase very few people would have the time and energy to engage in meaningful discussions of so many scientific topics in one go.  If I were you I would (a) restrict myself to one topic at a time and (b) pay attention to what is actually written in the responses to your posts.  Fail to do so and I suspect that you will find yourself recieving even more attention from the moderators.

    Moderator Response:

    [DB] Response to snipped off-topic and sloganeering snipped.

  13. Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    (-snip-).  Falsification is okay but it ought to be convergent.  And falsification is not nearly as important as verification.  What we want is convergent verification.  I don't think that Lu is going to get convergent verification.  I suspect that its just a matter of luck.  But to pretend that finding a correlation for an hypothesis is not even a valid part of the process appears "a bit rich" as it were. 

    Moderator Response:

    [DB] Off-topic snipped.

  14. Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    What you have, Chordotonal, is a scientist presenting a hypothesis and the proceeding to support that hypothesis by picking and choosing whatever evidence seems to support the hypothesis (don't look too closely) and ignoring whatever doesn't support it.  Need to get rid of CO2 as a GHG?  Ok, go all Angstrom and use the saturation argument.  Ignore the fact that it is completely unsupported in the literature.

    I imagine it passed peer review because it was reviewed by Lu's peers -- people who were not experts in the field and who had little idea of the mess that Lu was creating out of the existing literature.

  15. Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    (-snip-).  I don't think Lu 's hypothesis will pan out by the way.  But the process by which you prove things like this is going to involve curve fitting and correlation.  Its very strange to be clziming otherwise. 

    Moderator Response:

    [DB] Off-topic snipped.

  16. Dikran Marsupial at 00:55 AM on 8 June 2013
    Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    Chordotonal  wrote "With Lu there is nothing wrong with the evidence so far."

    Far from it, as discussed in the article itself.  If you want to engage in the discussion and support Lu's work then identify a specific flaw in the article and discuss it. 

    I suggest you read the comments policy, particular the item about sloganeering.  If you make posts that make arguments that are not backed up by evidence they are likely to be deleted. 

    (-snip-).

    Moderator Response:

    [DB] Response to off-topic snipped.

  17. Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    "Extraordinary claims, counter to large collections of existing work, require extraordinary evidence -"

    This phrase is from Carl Sagan. (-snip-).  Its actually a plea for a handicap. And to make such a plea would indicate that ones hypothesis needs a handicap.  (-snip-). (-snip-). 

    Moderator Response:

    [DB] Off-topic and sloganeering snipped.

  18. Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    Its a thing both odd and very ambitious to be using "Curve fitting" as a pejorative in science.  At least this fellow found a curve that fit. 

  19. Dikran Marsupial at 00:18 AM on 8 June 2013
    New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made

    CBDunkerson wrote "How could this Humlum paper have gotten through peer review?"

    Peer review can only be expected to be a basic sanity check, and sometimes the reviewers selected may not be sufficiently expert to spot the flaws.  The more times a paper is submitted to a journal, the more likely it is that some journal will accept it eventually.  Peer review has always been susceptible to the occasional failure, but science has adopted a good way of dealing with bad papers, which is to simply ignore them.  The problem comes when papers are written that have impact on the general public that don't have the background to see the errors.

    In many fields bad papers draw little attention from anyone, it is the public focus on climatology that means that the bad papers get exposed.  If "skeptics" didn't draw so much attention to them in the blogsphere/press, the bad climate papers would be simply ignored as well.

  20. It's soot

    Beyond that, though, what reality apparently ignores or is ignorant of are the following two realities:

    1. Global ice mass loss is in no way fundamental evidence ("trump card") for the theory of anthropogenic global warming.  It is evidence for the proposition that ice melts when conditions are physically conducive to melting.  If you want physical evidence of a warming planet, look at ocean heat content and the expected and observed shifts in general circulation.

    2. CMIP3 modelling severely underestimated Arctic sea ice loss (by 60-70 years).  If the reason for that underestimation is BC (and I'm not saying it is), then removing the BC signal would probably leave CMIP3 modelers (some of those tens of thousands of "warmist scientists") in a much improved position. 

     

  21. The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.

    Dr. Tung

    Why is the AMO used in this MLR analysis still detrended linearly?

    Please suggest a better way if you know of any. Note that to minimize collinearity in the MLR, the AMO index preferrably should not contain a trend, but you are encouraged to suggest different ways for detrending.

    I would strongly suggest theTrenberth Shea 2006 methodology, supported by Anderson et al 2012, as one detrending methodology worth considering.

    At the very least, I would suggest repeating your analysis with these and/or with a simple quadratic detrending - and determining the sensitivity of your analysis (and conclusions) to the choice of detrending method. That issue is, I believe, the core of these discussions, and a question well worth answering. 

  22. Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    John000 - I would suggest looking at the Climate Sensitivity thread, where the various uncertainties are discussed. 

    Estimates for climate sensitivity come from model results, from observations over the instrumental period, from responses to volcanic eruptions/aerosols, and paleo observations over the last few ice age cycles. Not just models! The climate sensitivity values used in such discussions are, in general, the synthesis of many lines of evidence, which is one of the reasons why extrema estimates such as Lu's tend to raise eyebrows.

    Extraordinary claims, counter to large collections of existing work, require extraordinary evidence - Lu has not supplied the same, nor answered earlier criticisms of his work. 

  23. Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    IanC#40:  Thank you, Ian.  You made good points.

  24. New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made

    @1 Esop

    Some positive: There was a good article/interview in Bergens Tidene last Wednesday (in Norwegian) with Bruno Latour, this year's Holbergsprisen vinner. He also made some excellent points about denying climate change in the print version, which I could not find online.

  25. New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made

    Mark, while the publication of your analysis is a wonderful response, I have to look at this Humlum paper and others like it with a growing sense of dread. It seems to me as if 'alternative realities' are creeping into science just as they have into politics, journalism, law, economics, and other formerly respectable fields.

    How could this Humlum paper have gotten through peer review? Why would Global and Planetary Change publish it? How can the universities that employee the authors not be embarrassed to be associated with this?

    I always thought that science was largely resistant to falsification because bad results would inevitably be uncovered and damage the credibility of all involved. Yet we seem to be seeing a lot of clearly wrong analysis getting published and no particular fallout when it is uncovered. Indeed, I doubt the denialsphere will stop praising Humlum in light of your findings... rather they will continue to accept his as valid and reject yours... creating two different views of reality. A situation I view with horror.

    Obviously, there has always been fringe 'science' and from time to time it has gotten published... but am I wrong in believing that things have changed in that we are now seeing it actively celebrated and promoted even in the face of proof to the contrary? I fear a future in which publishing bad science can be a path to greater carreer success. Rupert Murdoch's News Corporation routinely puts out false propaganda in the guise of journalims... and is beloved for it. Radical ideologues routinely get appointed to the highest courts despite rulings bearing no resemblance to legal precedent or justice. Raving lunatics frequently get elected to high political office. The whole world is suffering from the guidance of economists who promoted austerity during a massive global recession.

    If this kind of madness takes hold in the sciences we are truly doomed.

  26. It's soot

    Reality's writing here got me thinking of what would be the implications if the following claim would be true:

    "Arctic melt---and that of glaciers and the permafrost is caused not by CO2, but by black carbon[ soot] from the burning of forests and other biomass in China, India, Indonesia, other Asian countries and Brazil"

    My thinking is that the BC needs to be pretty well mixed into the upper layer of the troposphere in order to travel all the way to the arctic, and hence, it should be visible also in the Himalayas, even in the uppermost areas.

    So is it legitime to assume that in order for BC to be the dominant effect, and especially considering that the some of the listed countries surround the Himalayas, the effect should also be visible in upper levels of the said region. Ie. the topmost glaciers should also be darker and melting?

  27. Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    Dave@23 UV effets is a handwave at the change in the proportion of UV radiation in the solar spectrum within the solar cycle.  The increased UV below 306 nm then does increased photochemistry.  Lu does little more than handwave

  28. New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made

    reality @21.

    I would reinforce the message @24 by saying that you must be very careful with your language. You say " ...there is no acceleration in the rate of change of CO2." I don't know if the meaning is what you intended but it is not true. The rate of change of CO2 is not accelerating. Nor is it flat as you assert it is. It is increasing but roughly linearly, ie CO2 levels are accelerating at roughly a constant rate.

    A further argument for 100% of the increase being human in origin is the constant ratio between rises in atmospheric CO2 and emitted CO2 . Over the last 50 years that ratio has remained wobbling between 40% & 50% . And this ratio remains totally unaffected by the addition of the emissions from "China's huge growth in coal-fired power stations and cars etc in recent years" which may feature large in press reports but whose impacts are best analysed numerically.

    And long may that ratio stay 40-50%. If it starts dropping it will likely be due to feedback CO2 emissions from the melting cryosphere or warming oceans.

  29. New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made

    #21 reality

    The top graph is just some functions I made up to demonstrate what one part of their approach does. I found the visual impact helpful.

    The bottom one shows the components of CO2 rise and you can see that both human emissions and atmospheric CO2 accelerate. Over this time period the rates are extremely similar and if you directly compare atmospheric CO2 with human emissions then the correlation coefficient is about 0.99.

    By differentiating it you cut the cooefficient drastically, to around 0.4. This is because the short term variability masks much of it on short timescales, which was the point I tried to make with the top graphs!

  30. Dikran Marsupial at 18:46 PM on 7 June 2013
    New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made

    reality@21 Humlums argument is based on a (already well known) correlation between the rate of increase in atmospheric CO2 and temperature.  The rise in atmospheric CO2 is cause by the average rate of increase being positive.  Correllations however are insensitive to the average value of the signals, so the correllation between the rate of increase in atmospheric CO2 and temperature can not explain the increase itself.

    We know that the rise is caused by human emissions.  Atmospheric concentrations are rising more slowly than cumulative human emissions, so consevation of mass means that the natural environment must be a net carbon sink, taking more CO2 out of the atmosphere each year than it puts in.  There is a natural contribution, but it is strongly negative.

    The reason that there is little rate of increase while anthropogenic emissions have been rising approximately exponentially, is that rising atmospheric CO2 concentrations mean that the natural net carbon sink has been strengtheneing as well.  This gives rise to the constant so called "airborne fraction".  If you are happy with differential equations, there is a worked example in the paper I wrote which is referenced in my SkS article here.

  31. New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made

    Esop...

    What no attention is paid to by many warmist scientists, is the role of black carbon in the melting of the Arctic sea ice.

    Scientists, including Drew Shindell of NASA, Jacobson and Ramanthan amongst many others [ non-sceptics], met with Congress to tell them the results of  research that showed that ~50% of the Arctic melt---and that of glaciers and the permafrost is caused not by CO2, but by black carbon[ soot] from the burning of forests and other biomass in China, India, Indonesia, other Asian countries and Brazil---and a smaller amount from the burning of diesel fuel.

    Warmist scientists cite the Arctic melt as the trump card that 'proves' the earth is warming alarmingly, but they almost never mention the black carbon problem at all.

    Yet Drew shindell said that there's no point in only going after CO2 mitigation, since black carbon can be relatively easily mitigated with almost immediate effect.

    It would seem that scientists who don't mention BC, and pretend that the only impact on the melting in the Arctic is rising CO2 emissions ,are deceiving the world---not helping at all, when some clamor from them would help politicians to do what's necessary--especially as the Arctic melt has a catastrophic feedback in the lowering of albedo, by the formation of dark water where once there was ice.

     

    Moderator Response:

    [Dikran Marsupial] Discussion of black carbon is off-topic, this article is concerned with the cause of the increase in atmospheric CO2.  If you want to discuss black carbon, please find a more appropriate thread.

  32. New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made

    @21

    "What you object to in ..."

    Please read the article again. You have just created a strawman.

    "If the CO2 in the atmosphere ..."

    You are beating the strawman, 1. by ignoring the discussion and information given by others before your entry, 2. by ignoring the overwhelming evidence. Pretty much what Humlum et al. did ...

  33. New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made

    What you object to in Humlum's graphs seems to be that the constant nature of the increase in CO2---same gradient---when differentiated produces a flat line, showing that there is no acceleration in the rate of change of CO2.

    If the CO2 in the atmosphere was caused by human emissions, with little or no natural contribution, surely the curve would have a changing gradient [no longer linear and constant]  depicting the increases in emissions eg with China's huge growth in coal-fired power stations and cars etc in recent years.

  34. The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.

    In reply to MA Rodger at post 135: Four of us, Dikran Marsupial, Dumb Scientist, Jiansong Zhou and I, have spent hours making tens of thousands of Monte Carlo simulations trying to answer the question:  if the anthropogenic signal is highly nonlinear (quadratic or fifth order polynomial), will the linear detrending of the AMO index used in MLR necessarily leave us with a wrong linear anthropogenic trend?  The correct summary of our efforts so far ( I have not gotten to post 134 yet, but will shortly) should be, in my humble opinion, that we have not found such an example (although we should always be on guard for such a possibility). This is despite some of the extreme examples constructed and discussed here, and undoubtedly more such examples have been tried but not shown here ( I know we have tried many).  A thank you is in order to the three of you. 

    I therefore disagree with your summary:

    In this thread, it has been demonstrated by Dikran Marsupial & also Dumb Scientist that the MLR analysis is sensitive to an underlying quadratic trend if a sinusoidal signal used in the MLR is linearly detrended when the trend it contains is quadratic.

    In all logical and semi-realistic cases, the MLR so far has yielded the right answer within its 95% confidence internal, although in some cases, the "right" answer is useless because the error bars are too large.  We think we understand why in some of these hypothetical cases the error bars are so large.  Fortunately the error bars are usefully smaller for the real data.

    Given this situation, here is the question:-

    Why is the AMO used in this MLR analysis still detrended linearly?

    Please suggest a better way if you know of any. Note that to minimize collinearity in the MLR, the AMO index preferrably should not contain a trend, but you are encouraged to suggest different ways for detrending.

  35. Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    Calling the Science Daily piece an 'article' is generous - it's just a reprint of the press release, which is all Science Daily does. Of course, this didn't stop it being cited as supporting the research by The Australian's consistently abysmal Cut & Pate column.

  36. Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    Hi John,

    Indeed there is still a large uncertainty in the equilibrium climate sensitivity (ECS), primarily due to cloud feedback, which dominates the uncertainty: the range of cloud feedback in 12 models is almost as large as the spread in ECS itself; I think this is unlikely to converge until we get to the point where clouds can be modelled somewhat explicitely.

    Even though the spread among model is large, the important thing is that even if you pick out the best case scenario for each feedback aong the models in Dufresne and Bony 2008 (i.e. model 1 for surface albedo and water vapour+lapse rate, model 2 for cloud feedback, you will still get a warming that is very close to 2 degrees. In other words, there is very strong evidence that warming will not be less then a degree.

    Climate model is really just a way for us to quantify our physical understanding. Skeptics often point to the uncertainty as a problem, but I think the right way to look at the spread is that we can implement our current knowledge in 12 different ways, and under no circumstances is the warming neglible.

    Yes, most of the time ECS is used instead of splitting it up to alpha and beta, I think the reason is that you can't in reality increase the temperature without the water vapour feedback, so making the distinction between the two is pointless for most applications.

     

  37. New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made

    #15 chris : thanks for the mention, it appears to have dropped out due to a minor technical problem, I have contacted the publisher about returning the reference to the bibliography.

    #6 HJones : Figure 1 is only an example of what happens with a linear trend and cycles. Two more points are 1) The green line is cycles, which would be the 'natural' case. The blue line is what would happen with a constant flux from humans. 2) the real human emissions (and contribution to atmospheric CO2) have accelerated, which was why a correlation was easier to pick out.

    #18 Jonas : differentiating a linear function returns the gradient, e.g. dy/dx when y=5x returns 5. That's why my first graph has the blue line as a constant value of 1.

  38. New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made

    KR @14.

    And indeed Tamino was correct in his 'pointing' although the rate of increase in CO2 forcing has been looking somewhat borderline linear in recent years. This is perhaps surprising given the strong rises in CO2 emissions over the last decade. Certainly the slow rise in emissions during the 70s & 90s are now replaced by far faster rates, in ppm the fastest on record by far. Yet that is the thing with exponential growth - it is very difficult to maintain.

    And it is mainly because of those 70s & 90s slowdowns that CO2 emissions are not exponential. Indeed the period 1960-2010 (or to date even) can be seen as less-than-exponential since 1969.

  39. HeisenIceBerg at 09:15 AM on 7 June 2013
    Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    Well, this is embarrassing. Not only do I currently attend the University of Waterloo, but I’m also physics major. Professor Lu’s main research areas are:

    • Biophysics and biochemistry (molecular switches controlling DNA damage and cell death)
    • Ultrafast laser spectroscopic techniques
    • Nanometer-scale surface science
    • Environmental/atmospheric science (ozone depletion science)

    I took those directly from his department profile page.  The last one seems oddly out of place as compared to the others, though his past study of ozone depletion would explain his predisposition toward CFCs.

  40. New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made

    Differentiating a linear function yields zero. Differentiating a cyclic function (sine/cosine) yields a shifted cyclic function: removing a linear that way trend proves only one thing: the disinterest in the linear trend. 

    I wonder how this passed through "peer review". It would be interesting to have a correlation of "journal name" with "disproven paper" (as opposed to refined/enhanced paper) ...

    On the other hand, we can interpret that thing in a different(iated?) way: temperature change (even the small detrended/differentiated change) correlates with CO2: QED! Thanks Humulum, you just "proved" the CO2 effect, and when switching back to the real world (non detrended), the result is: lineraly increasing human CO2 emissions cause climate change ...

  41. Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    Hi Ian,

    Very good interpretation of the climate sensitivity and good comment on Lu's paper.

     

    But I still have one question.  Suppose that the equilibrium climate sensitivity finally to calculate the temperature change due to a radiative force is equal to the value of alpha times beta.  You say that alpha =1.1 deg with good certainty. But if beta has a large range of uncertainties, then the equilibrum climate sensitivity still has a large range of uncentainties.  And you would probably agree that in the literature, researchers sometimes just use the equilibrium climate senstivity without separating alpha and beta.

    Thanks.

  42. The anthropogenic global warming rate: Is it steady for the last 100 years? Part 2.

    Perhaps those who are discussing these issues should read THIS paper before continuing further:

    http://link.springer.com/content/pdf/10.1007%2Fs00382-013-1669-0.pdf

  43. Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    John,

    First off, IPCC does not develope climate models, and they only summarize published results; the model themselves are developed by independent research groups all around the world. 

    One thing that you have to understand about climate sensitivity itself is an idea that helps us understand and characterize the bulk behaviour of climate models, and it is not a parameter that can be set a priori. 

    The parameter alpha, which I think is the same as the Plack response, describes how the earth will warm/cool according to a change in radiative force, whether due to sun or greenhouse gases, in the absernce of feedback. This is very well constrained, as it is from (relatively) simple physics. All climate models agree on this very well; and you can see it from a graph from Dufresne and Bony 2008: all models gives a planck feedback of 1.1 degrees.

    The real uncertainly is on the feedback (beta), and this is entirely responsible for the range of uncertainties: 2.3-4.2 degrees for doubling of CO2. Even this can be broken into its components: surface albedo (ice cover etc.), water vapour, and cloud feedback. You can see that the most of the uncertainty comes from changes to clouds; this is is of course a known limitation to current climate models.

    To reiterate, climate sensitivity cannot be set and it simply reflects our understanding of the various aspect of climate physics, and the uncertainty in climate sensitivity reflects uncertainty in our understanding as well as constraints on our ability to quantify this understanding through a climate model.

    Whether 2.3-4.2 degrees is large depends on what you are looking at. From a purely scietific point of view it is rather large, but from a broader perspective it is not: what matters is that we are quite certain that it is above 1, and likely above 2, which is more important from a policy point of view.

    Also I shold clarify that curve fitting can be very informative if done correctly, and the results are interpreted with care. Unfortunately Lu's paper is not one of them IMO.

  44. New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made

    It's sad that we still have to combat such inane nonsense as this Humlum paper.  Surely there are better things for intelligent climate scientists to be doing?

  45. Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    Co2 above the tropopause (e.g. in the stratosphere and thermosphere) is a coolant because it radiates after collisional excitation, but there is little upwelling radiation in spectral regions where it can absorb.  Net result is that it pushes more radiative energy out to space than it absorbs from below and acts as a coolant.  See, for example

    http://www.atmosphere.mpg.de/enid/20c.html

    Recently, Eli asked Leif Svagaard about

    "Has anyone worked on adjusting pre 1979 solar irradiance reconstructions based on Kopp and Lean (2011)?

    http://www.dtic.mil/dtic/tr/fulltext/u2/a535690.pdf

    http://rabett.blogspot.com/2013/03/the-blog-of-new-sun.html

    which drops the solar constant to 1361 W/m2, decreases the peak to minimum intensity a bit and straightens out time history since 1979 and basically makes anything said about TSI previously, both for before 1979 and after wrong,  and got this reply

    "yes, almost all the old stuff is obsolete. That does not deter the enthusiasts, of course"

    Prof. Lu is very enthusiastic. Not very well informed, but very enthusiastic

  46. JosHagelaars at 07:15 AM on 7 June 2013
    New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made

    Thanks for the post, excellent work!

    Humlum's paper is full of extreme statements, one example: "Empirical observations indicate that changes in temperature generally are driving changes in atmospheric CO2, and not the other way around.". Humlum 'forgot' the existence of ENSO and other factors that have a large influence on the annual growth rate of CO2. Scientific omissions, a professor unworthy.

    For Dutch readers, we covered the online release of Humlum's paper in September 2012 on Klimaatverandering - Humlum: over emissies en omissies.

  47. Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    John001 @33 - equilibrium climate sensitivity is a physical output from a climate model.  It's not based on 'curve fitting' at all.

  48. Lu Blames Global Warming on CFCs (Curve Fitting Correlations)

    John001 @31 - you're missing a key difference.  Solanki and Krivova and the part of my blog post you reference weren't trying to determine how much global warming has been caused by the sun.  We were looking at correlations and/or trying to figure out the maximum possible solar contribution.  What Lu did was assume that the maximum possible solar contribution is reality, without providing any evidence to support that assumption.

    The difference with respect to Foster and Rahmstorf is that F&R also accounted for all other known large natural temperature influences in their multiple regression.

  49. Rob Nicholls at 06:48 AM on 7 June 2013
    Will Tropical Forests Remain Carbon Sinks?

    Matthew L, I agree entirely that nature is wonderful. Unfortunately I'm not optimistic that nature will prevent us causing a mass-extinction if our civilisation continues along the path of increasing fossil fuel burning. There have been mass-extinctions in the past when large changes in temperature have happened in a short time (on a geological time-scale), and we seem to be on track to cause similar abrupt changes in temperature (unless we change course radically). Even if there isn't a mass extinction, I think that global warming is likely to cause food security problems for a sizeable proportion of humanity. I'm not sure how well the world's agricultural systems will cope with the high temperature extremes and changes in rainfall in the coming decades. CO2 fertilisation won't necessarily help in the future in areas where plants are unable to grow due to extreme heat or drought.

  50. New study by Skeptical Science author finds 100% of atmospheric CO2 rise is man-made

    MarkR, Don't forget to add Humlum et al to the reference list in your comment when you get the proofs to review!

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