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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Comments 41901 to 41950:

  1. Lawson, Climate Change and the Power of Wishful Thinking
    Lawson is an idiot. What a shame, though, that his last sentence is almost certainly true (with high confidence).
  2. CO2 is just a trace gas

    Bob Loblaw @16, your definition is non-standard.

    The best definition of the atmospheric greenhouse effect is the difference in upward longwave radiation at the TOA to that at the surface due to absorption and emission of longwave radiation be components of the atmosphere.

    Based on that definition, clouds contribute approximately 25% of the total current greenhouse effect, coming in behind water vapour (50%) but ahead of CO2 (20%).  (See link in my post responding to Undecided Molecular Biologist above.)

  3. CO2 is just a trace gas

    Undecided Molecular Biologist @5 & 8, here is a spectrum of infrared radiation to space at the Top of the Atmosphere as calculated by the Modtran Model:

    The important points are:

    1)  The Earth's TOA black body radiation without a greenhouse effect would follow the shape of the coloured lines (black body radiation curves), with the specific shape depending on surface temperature;

    2)  The absorption of IR radiation from the below, and reemission at a higher cooler altitude results in a reduction in the TOA outgoing radiation, by the amount shown by the red shading;

    3)  The largest single factor in that reduction is H2O with absorption and reemission at wave numbers less than 550 and greater than 1300 (the initial dip around 1250 is due to methane); 

    4)  The second largest single factor in that reduction is that due to CO2 at a wave number of about 650;

    5)  The reduction to CO2 is almost as large as that due to H2O in a clear sky;

    6)  Although there is some overlap of H2O absorption and CO2 absorption, because CO2 is higher in the sky (as can be seen by its lower temperature of emission), it would have the same effect even in the absence of the H2O, so that the H2O has no effect in areas of overlap; and

    7)  The large CO2 absorption band is located near the peak of terrestial emissions allowing it to have a much larger impact than other absorbers.

    Modtran is only a model, so you may be disinterested in what it shows.  Such models have been compared with observations, however, and shown to be remarkably accurate.  An early such comparison was published in 1969:

    These and similar observations show that your parade of "corrects" are based on prejudicial thinking rather than on actually looking at the observational data on the issue.  Absent such prejudicial reasoning, it can be discovered that CO2 is responsible for approximately 20% of the all sky greenhouse effect. 

  4. Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy

    1) I believe that figure 2 (the trend comparison) would be improved by also showing the AR4 trend, using observed data for the years 1990-2000 (as AR4 projections start in 2001).

    2)  McKittrick did worse than simply eyeballing the trends.  Anybody with any experience in eyeballing trends could see from the draft figure that the trend for observations (and of AR4 plus observations from 1990-2000) would pass well below the 1990 point in the observations due to the large temperature excursion due to the Mount Pinatubo erruption.  In fact, had the draft report baselined the graph by ensuring all trends passed through the same point in 1990 (a perfectly reasonable procedure), that would have lifted the observations relative to the FAR, SAR, and TAR projections.  Indeed, sufficiently to place them in the upper half of TAR projections (from my eyeball estimate).  It would not have significantly shifted the them relative to an observations to 2000 plus AR4 due to the shared initial data.

    Because much of this shift would be due to the Mount Pinatubo erruption, that may seem like an unfair comparison.  To avoid that, the proper method is to use an extended baseline, as above, or to set the data for a common origin of trends having adjusted the data for short term factors not expected effect the long term trend, ie, something like this:

     

  5. IPCC model global warming projections have done much better than you think

    Thanks Bob.

    Unfortunately it is possible to obfuscate even the basic science unless it is codified in some form and the essential assumptions are clearly documented in a paper or analysis.

    For example, it is now required that all randomised control studies and other research reveal their power calculations as part of journal submissions. There are a number of assumptions underlying that as well and they can be questioned but it helps to quickly terminate papers that have insufficient statistical power to address the null hypothesis.

    I maybe naive because the depth of "declaration" of what is being assumed could
     include euclidean geometry being correct, but at least amongst the sophisticated
     scientists grappling with core issues, there could be a higher level and more
     explicit level of declared assumptions. And there could at least be a declared
     concensus or manifesto if you like of what are unchallengeable assumption underlying analyses.

    I am at least able to conduct a basic MLR and understand the judgements that
     apply, but it appears to me that in in addition to statistical treatment decisions, climate science often has very basic processes routinely questioned by people with
     the undergraduate (at least) training to know or know better.

    It is very confusing for outsiders in any field to judge the validity of arguments when credentialled people claim widely disparate conclusions based on very or mildly disparate assumptions.

    I really don't expect to read a paper where the mixing depth of oceans is disputed anymore than I expect a physicist to dispute the molecular weight of carbon or
     at least within agreed bounds.


    Thanks again.

  6. Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy

    Ross McKitrick brilliant? I do not think so.

  7. IPCC model global warming projections have done much better than you think

    sereniac: "there has not been open and transparent declaration and agreement on the basic assumptions behind basic positions."

    As you learn more, you will tend to find the following:

    - on what I will call the science side, there is pretty strong agreement about many of the basic assumptions. After all, a lot of the basics were worked out in the 1800s. (Yes, that is the 1800s. Not a typo.) For a look at this history, try this link. Scientists usually don't spend a lot of time discussing the basics that were agreed upon over 100 years ago. You learn them as an undergard, and move on.

    - on what I will call the "skeptics" side (although they are clearly not true skeptics), you will discover many mutally contradictory assumptions, which change with the shifting wind. They will assume whatever will lead to the conclusion they want, and then assume the opposite in another situation. Consistency is not a priority. If you follow the Arguments menu below the Skeptical Science masthead (at the top of every SkS page) to the Contradictions page, you'll end up here, where many of the "skeptical" contradictions are listed. The "skeptics" can't even agree amongst themselves what the basic assumptions are, let alone agree with the scientists.

    I take that back: the "skeptics" do have one fundamental assumption that is constant behind every argument: that the climate science is wrong. Everything else is malleable to fit that assumption.

  8. IPCC model global warming projections have done much better than you think

    Thanks for the Loehle/Scafetta critique.

    I have to confess that I really believe that a huge amount of the animosity and confusion associated with the AGW issue arises because there has not been open and transparent declaration and agreement on the basic assumptions behind basic positions.

    It is extremely frustrating for everyone to burrow through analyses only to find what SHOULD be a known physical fact being disputed e.g. depths of ocean mixing or whatever. Or CO2 solubility or whatever.

    I don't attribute blame disproportionatley here and it seems to me that all sides would achieve clarity and progress if these fundamentals were agreed to in some manifesto.

    That would at least provide a focal point where analyses could be dismissed outright because they did not adhere to assumption 3.4.3.1(a) or whatever.

    I realise this would be  very contentious exercise in itself and some would argue just as much work as the IPCC itself, but I have to be candid, as an outsider it is somewhat like  reading an orbital calculation where the altitude of the orbit is in dispute because of differences in judgements of what "counts" for the height of Everest.

    It's not just silly. It's ridiculous.

    Scientists should be able to reject that orbit because the height of Everest is agreed

    to be Xmm plus or minus whatever due to thermal expansions, storms or whatever.

     

    Really this seems to have become the ultimate case of apples and oranges.

    Sorry if I come across as frustrated- I'm sure many of you are as well and possibly

    exhausted by the number of apples you see counted as oranges.

     

    But truly, science just cannot progress efficiently without a clear declaration and

    agreement of (a) what is known and (b) what is assumed in the science of climate. Doing so must decrease the statistical uncertainties involved.

    I shall go back inside my box.


    Thanks again

  9. Residence Time and Prof Essenhigh

    I do not think that Essenhigh's calculation of the residence time is accurate. Majority of CO2 molecules absorbed by the ocean and vegetation are not removed permanently but returned back to the atmosphere. So the more appropriate analogy would be: 150 people are processed an hour form the 750 in queue. 140 of them are returned back to queue, thus only 10 are removed from queue. Consequently the real residence time is 75 years, not 5.

  10. IPCC model global warming projections have done much better than you think

    Damn

     

    Forgot the link. http://www.appinsys.com/globalwarming/SixtyYearCycle.htm

    thank you

    Moderator Response:

    [DB] Much of your link is addressed here:

    Loehle and Scafetta find a 60 year cycle causing global warming

  11. IPCC model global warming projections have done much better than you think

    Clearly there is a lot of variability in the quality of evidence and debate on the AGW issue.

    I have to say I have read a lot of unconvincing material on both sides of the argument.

    I also understand that there is a limit to which the intelligent layman can come to terms with this material. Yet some of us try and the better we're informed, the better the outcome for all of us- i hope.

    This site does at least reference some of the more respectable physics/scientific literature and is claiming I think the existence of a 60 years natural cycle which is driving climate behaviour in addition to GHGs, ENSO etc etc.

    I haven't backtracked to its home page since I would prefer to encounter the arguments on their merit and I have in the past been swayed in many directions based on my judgements of the ideoloogical commitment of a source.

    I would welcome any commentary on this. I have found the recent research convincing- that which identifies variation in ENSO hiding a long term warming trend.

    I suspect it is unlikely that mainstream analysts would have missed a 60 year cycle and I also suspect that this assertion is based on starting points (aren't they all?) as well,
     still I like to hear what people have to say and for me, the array of evidence appeared
     interesting, although again it may turn out to be selective.

     

    Thanks again

  12. IPCC model global warming projections have done much better than you think

    Thanks John.

    Maybe I phrased it wrongly. Perhaps these graphs show the ability of different models to reproduce *past* climate behaviour.

    If do, it would appear that a number are better than others.

    My question is therefore why not select those that match past climate the best,

    run those and thereby produce the projections.

    I don't understand the logic of retaining models that are poor in matching

    past climate.

    I suspect that a number of models that are poor in matching past climate have been retained because their assumptions are reasonable/logical and that even though they may not match past climate all that well, this may be a data problem and that
    *not* including them in the suite would mean that reasonable/known features of the climate would not be represented in the projections.

    Is that sort of it?

    Moderator Response:

    [JH] You have made numerous assertions without providing a single reference or citation to identify the source of your claims. Thus your assertions are nothing more than your opinions which do not carry much weight on this site.

  13. IPCC model global warming projections have done much better than you think

    Sereniac #84:

    The climate models used by the IPCC are designed to make long-range forecasts. Unless we have a time machine, we cannot jump ahead to the year 2100 say and ascertain which sets of models are performing best.

     

    For the human race, there is no Planet B!  

  14. IPCC model global warming projections have done much better than you think

    Thanks for the commentary regarding the notion of La Nina as a negative feedback dampener of AGW.

    I have a question that has probably been asked many times before somewhere but

    have not found it answered.

    Q: When placed on a common graph, some models appear to be very poor compared to others. Why weren't these eliminated from the suite and the better models run more frquently? It would seem to me that this would tighten up the range of predictions.

    It just seems odd to me since my natural inclination would be to eliminate those models that don't seem to map onto actual climate behaviour very well.

     

    Thanks again

  15. CO2 is just a trace gas

    Undecided: "You both refer to mathematical "proof" that CO2 is indeed a "very active" substance via models."

    You have hand-waved away the effect of CO2 by using vague, ill-defined terms such as "not very active", "tiny absorption bands", and "very weak". Your "proof" is nothing more than an assertion.

    People are trying to point out to you that when you actually put numbers on "not very active", "tiny absorption bands", and "very weak", and do the math, the result says that the amount of CO2 in the atmosphere is actually important. It really does affect the radiation balance, and it really does increase global surface temperatures.

    You may think that handwaving trumps a mathematical calculation. Science generally takes the opposite view.

  16. CO2 is just a trace gas

    Robert: how do you define "greenhouse effect"?

    Clouds do asborb IR. But the greenhouse effect is traditionally thought of as the atmospheric effect where the atmosphere is transparent to visible sunlight, and relatively opaque to IR. Radiation from the sun reaches the surface easily, but is impeded on the way back out. As you note, clouds are not particualrly transparent to visible light. Thus, by my definition, they are not part of the greenhouse effect.

  17. CO2 is just a trace gas

    #11:

    http://skepticalscience.com/argument.php?a=185#98478

    "The comment in Pierrehumbert's book refers to clouds (which do not contribute to the greenhouse effect)..."

    I was under the impression that clouds did indeed contribute to the greenhouse effect, though the total forcing from them is negative when you take into account the increase in albedo.  The cloud feedback due to temp changes is thought to be most likely positive, though that is not certain.  I do however understand that UMB misread
    Pierrehumbert, who as you say was talking about the uncertainty in the cloud feedback.  That's not true with the water vapor feedback, which we know is strongly positive. 


  18. Residence Time and Prof Essenhigh

    "Prof David MacKay’s [3] highly readable Sustainable Energy: Without The Hot Air"  This link is not working.  I think it wants to go to: http://www.withouthotair.com/

  19. Lawson, Climate Change and the Power of Wishful Thinking

    Margaret Thatcher's use of climate change was not as pure as the driven snow.  She was trying to break the strangle hold that the coal industry had on Great Britain and climate change was one of her weapons.  Whether she was convinced of the reality of climate change or not is a moot point. 

  20. Lawson, Climate Change and the Power of Wishful Thinking

    An open letter to Mr Lawson

    Dear Mr Lawson

    Let's say for the sake of the argument that you are correct and this 15 year hiatus in surface warming will continue. Let's even say that the climate will begin to cool. Let us further agree that all the Ago floats have a calibration error and the missing heat is not going into the oceans. Let us even agree that sea level rise has stabilized and will continue at only about 3mm per year for the rest of the century. Even with all of the above, there remain so many reasons to wean ourselves off fossil fuels. I assume you receive none of your funding from the fossil fuel industry and your arguments come from a deep conviction. Have a quick glance over the following link.
    http://mtkass.blogspot.co.nz/2010/10/forget-climate-change.html

  21. CO2 is just a trace gas

    UMB - Follow the logic train;

    1. Without atmospheric CO2 there would be no green plants
    2. Without green plants most animals would die
    3. Therefor, atmospheric CO2 can reasonably be said to have a 'large' effect
    4. Therefor claims that atmospheric CO2 is too small a trace gas to have any large effect are false
  22. Dikran Marsupial at 04:36 AM on 4 October 2013
    CO2 is just a trace gas

    Undecided Molecular Biologist: To get the discussion onto a more productive footing, do you agree that the theory of the enhanced greenhouse effect (see e.g. here for a brief explanation of the basic mechanism) that predicts warming as the result of increases in atmospheric CO2 is based on the recognised absorption characteristics of CO2 that you have mentioned?

  23. Dikran Marsupial at 04:20 AM on 4 October 2013
    Residence Time and Prof Essenhigh

    BillEverett The link http://pubs.acs.org/doi/abs/10.1021/ef200914u works for me.  Hopefully the link in the article will be fixed shortly.

  24. Dikran Marsupial at 04:16 AM on 4 October 2013
    CO2 is just a trace gas

    undecided The comment in Pierrehumbert's book refers to clouds (which do not contribute to the greenhouse effect), not water vapor (which does), and so does not in any way support your earlier comments regarding H2O versus CO2.

    Pierrehumbert, like many climatologists, is perfectly happy to talk about the limitations of the models, however he are still willing to use them.  The fact that this is the case should give you pause for thought, that just perhaps you are blowing the limitations out of all proportion, and that perhaps you need to actually read the books and papers that explain how the models work, rather than just read the opening remarks until you find a comment that you can use to support your position.

  25. CO2 is just a trace gas

    As a follow-up to my comment #9, I should like to add the following summary:

    The claims of denialists notwithstanding, the fact of the matter is, like any well-validated science, climatology is backed up by the three-fold combination of:

    (1) Theory - the known physics of radiative transfer, bulk heat transfer in the atmosphere & oceans, the radiative properties of greenhouse gas molecules, etc. etc. etc.;

    (2) Experiment - e.g. Tyndall's work in the 19th century, modern climate modelling, etc.; and

    (3) Observations - e.g. satellite era research showing the top-of-atmosphere energy imbalance, ARGO floats finding immense increases in ocean heat content, global cryosphere melt, and so on (and on and on...)

    I can assure you, Undecided, and any other readers, that the findings of climatology cannot be so easily tossed aside by casual references to bad financial modelling in the last decade: any attempt to overturn it has to come to grips with the theory, experiment, and observations.

  26. CO2 is just a trace gas

    Undecided Molecular Biologist:

    There's nothing for it but to say that you appear to be operating with an extraordinary misconception of the underpinnings of climate science. Just imagine some random person coming along and spouting off completely off-base stuff about molecular biology. That is what your comment #8 looks like with respect to climatology.

    Climate models are emphatically not the underpinning of climate science. If anything, they're latecomers to the game. Climate science begins with the paleoclimatic studies of ice ages and the experiments of Tyndall in the 19th century, not with the hi-falutin' models discussed in IPCC reports.

    Our present understanding of climate and of greenhouse gases follows, of necessity, from the physical properties of greenhouse gas molecules themselves and their IR-radiative behaviour. As far as I am aware, these properties were more or less completely determined in the 1950s and 60s.

    The understanding that CO2 is a critical forcing while H2O is a feedback (that is, H2O does not force climate changes, it can only amplify them) also follows of necessity from the same physical properties.

    What is more, we have access to empirical data from paleoclimate research and recent records-keeping, which we can use to validate modelling. As far as I am aware the bulk of empirical data strongly supports the mainstream understanding of climate.

    I have nothing to say about your attempt to draw an analogy between climate modelling and a particular set of financial modelling (if indeed you have characterized the latter accurately) or your final remarks, which IMO amount to issue-trolling, however well meant they may be.

  27. Undecided Molecular Biologist at 02:38 AM on 4 October 2013
    CO2 is just a trace gas

    You both refer to mathematical "proof" that CO2 is indeed a "very active" substance via models. This probably risks needing to move the subject to another thread, but to continue the point -
    Pierrehumberts book states very aggressively in his opening remarks, just one (of potentially thousands) of flaws in climate model calculations. Namely that water, or indeed clouds, pose a very severe challenge to the understanding of climate. One calculation error on either side of the effect clouds have upon radiative forcing, will destroy a model.
    When the number of interacting variables in a model reaches numbers that clearly climate science does, they have to be wrong, they will be wrong. Pure common sense says this. Indeed, you can back-model climate to check if you are right, but that is including the known variables. Bankers back-modelled AAA rated financial products 5 years ago. There was overwhelming consensus that they were right in their own (greedy-world) of peer reviewing each other’s work. Trillions were invested "risk-free".
    To model the risk profile of a AAA rated asset backed collection of securities is a piece of cake compared to trying to model climate science. And what happened?
    They were wrong. They missed a simple variable and the model broke. Trillions lost and global recession we are still feeling the effects of. Big mistake by an overwhelming consensus at the time and by (simple by comparison) models being wrong.
    I worry that the climate movement has made a grave mistake in backing CO2 as the driver of climate change....
    If it is proven to be a mistake, public will lose confidence and trust in the environmental movement and I fear even more important issues such as habitat loss, population growth, antibiotic use and sustainable practices will get effected.
    This is my big fear

    Moderator Response:

    [JH] You are now skating on the thin ice of sloganeering and excessive repititon -- both of which are prohibted by the SkS Comment Policy. Please cease and desist, or face the consequences. 

    [Rob P] Allcaps removed. See comments policy.

  28. Residence Time and Prof Essenhigh

    The link in "Thankfully Gavin Cawley has now managed to publish a response, which should settle the matter (http://pubs.acs.org/doi/abs/10.1021/ef200914u)" doesn't work.

  29. Lawson, Climate Change and the Power of Wishful Thinking

    Agree with the comment that repetition is important to the rhetoric of denialism.  Recalls the strategy that Dick Cheney & Co. used to attempt to justify the US invasion of Iraq: "Lie; Retreat; Repeat.  Lie; Retreat; Repeat."   The difference is that global warming denialists don't much bother with the "retreat" part.  They just lie and repeat the lie.  They are that much more shameless.  

  30. Dikran Marsupial at 23:55 PM on 3 October 2013
    Residence Time and Prof Essenhigh

    BojanD/XRAY1061 The fact that CO2 levels have been increasing at a time anthropogenic emissions have been rising doesn't disprove Essenhigh's hypothesis, but the fact that they have been rising more slowly than anthropogenic emissions does (as Tom points out).

    The error usually made by these types of argument is to compare the gross volume of anthropogenic and natural fluxes into the atmosphere without considering the fluxes out of the atmosphere as well.  The rise in atmospheric CO2 levels is caused by the difference between total emissions and total uptake.  Anthropogenic emissions are small compared to natural emissions, but natural uptake is bigger still, and it is the difference between natural emissions and natural uptake that determines the natural comtribution of CO2 to the atmosphere (and it is negative!).

    FWIW Essenhigh's paper says very little about what is causing the rise in atmospheric CO2, just that it can't be anthropogenic because the residence time is short.  My paper explains why this is incorrect, residence time is short (4-5 years), but the conclusion does not follow.

    Anyone can make a mistake, however the NIPCC report cites Essenhigh's paper and uses similar arguments, that is a far more egregious error as the problems with Essenhigh's paper had already been widely discussed in climate blogs and in the journal itself.  It would ony take a google scholar search of the papers that cite Essenhigh's to have discovered that, which is basic scholarship.

  31. Residence Time and Prof Essenhigh

    Therefore the mere fact of the increase does not prove that the increase was anthropogenic.


    I think that's not what XRAY1961 had in mind. I think he meant that since Essenhigh implies (or openly states?) that anthropogenic contribution is negligible, then the source of rising CO2 concentrations should be huge and therefore not difficult to isolate. So I wouldn't go with 'completely disproves', but it gives it a lot of problems.

    It's astonishing that such faulty papers could get published. Beyond belief, really. I guess a college student could make such a mistake, but this ...

  32. CO2 is just a trace gas

    UMB, what sort of "If by Whiskey" argument is that?  The relative strengths of the various greenhouse gases have been directly measured (example) from surface.  You know that, of course, and so I'm wondering why you're engaged in semantics when you could be going through the math.  If you want to talk about tiny changes, why not point out that if we use the full Kelvin scale up to the max GMST for the last 550 million years, a change of -3% results in a massive ice age.  A change of less than 0.2% resulted in the LIA.

    You might also check out this series of articles (the author welcomes feedback from those able to do the math).

    "reflector"?

  33. Dikran Marsupial at 23:01 PM on 3 October 2013
    CO2 is just a trace gas

    Undecided Molecular Biologist The basic mathematics of the enhanced greenhouse effect was worked out by Gilbert Plass back in the 50s, and the calculations were based on the "small" amount of the IR spectrum that CO2 actually absorbs that you mention.  The reason this can have a great effect is that the sun provides a very large amount of energy into the climate system, so (loosely speaking) you only need a small proportional change in the amount that escapes can have a big effect on surface temperatures.

    I suggest you get a copy of Pierrehumbert's book "Principles of Planetary Climate", and follow the maths, and you will find out how the greenhouse effect actually works and you will understand how important these small absorbtion bands are.

  34. Undecided Molecular Biologist at 21:11 PM on 3 October 2013
    CO2 is just a trace gas

    "Small amounts of very active substances can cause large effects"

    Yes.  But only if that substance is "very active".

    IS CO2 indeed "very active"?

    it only reflects IR "black body" radiation.  therefore is it not very active in terms of effecting heat, which spans a much longer band of wavelength than just bloack body IR.

    Even within the IR black-body band, CO2 only effects three tiny absorbtion bands that account for 8% of the "black body" wavelenths.

    Correct?

    If this is correct, CO2 is 100% not "a very active substance".

    Rather a better description is that it is a "very weak" reflector of heat.

    Correct?

    Water is a far more powerful green house gas both because of the level of heat it is able to reflect, but also the massive concentration of H2O in the atmosphere.

    Correct?

    back to CO2 - when you combine the fact that it seems to be a very weak reflector of the overall heat spectrum, combined with the fact it is present by concentration 0.03% of air, surwely the climate change movement might have made a massive mistake in placing CO2 as the central cause of global warming?

    ....when you heat water, it releases gasses including CO2, hence could CO2 in past warmings be an effect rather than a cuase?

     

    Moderator Response:

    [Rob P] Allcaps removed. Further transgressions will result in comment deletion.

  35. Residence Time and Prof Essenhigh

    XRAY1961 @1, there have, in the past, been increases in CO2 concentration as large, and even larger than that (though probably not as rapidly).  Therefore the mere fact of the increase does not prove that the increase was anthropogenic.  Further, it is logically possible that the timing was mere coincidence - so while that timing is highly suggestive of the cause, it does not establish it to the standard scientists would normally accept.  Fortunately, there are at least nine other lines of evidence that, together, establish beyond any reasonable doubt that the rise in CO2 concentration is anthropogenic.

    Of these, one of the most important, and the one that Gavin Cawley most favours, is the mass balance argument.  We know that the CO2 increase was anthropogenic, because each year, the total increase in CO2 is less than we put into the atmosphere.  Therefore nature is taking CO2 out of the atmosphere each year, and consequently cannot have caused the rise in CO2 concentration.

     

  36. Secretary of State Kerry and Senator Boxer Remark on the IPCC Report

    William at @12

    "And yet, with a stroke of the pen, the politicians could have a profound effect on the problem"

    As could voters with a check of the correct ballot box or we emitters by not flying, travelling so much and by installing renewables.. and yet ??

    Professor Kevin Anderson (Tyndall Climate Centre) speaks to the latter here

  37. IPCC model global warming projections have done much better than you think

    Sereniac #81

    I think that's the most interesting question IMO. Based on the evidence we've got so far, the only sensible suggestion for the lower predictions of warming favoured by the 'skeptics' is that we get some change in ocean circulation that keeps trying to hide the heat.

    We have some evidence we can call on.

    Firstly, models generally predict more El Ninos with warming, so we don't know about a physical mechanism to cause a mostly La Nina state.

    Secondly, back in the warmth of the Pliocene, it seems that there were permanent El Ninos (Ravelo et al., 2006), the opposite of what you'd need.

    Perhaps other changes in ocean circulation outside El Nino could be a negative feedback, but aside from drastic changes like the closing of the Isthmus of Panama which triggered the Gulf Stream, or the draining of Lake Agassiz which cut it off for a bit, there isn't evidence because once again: models don't give a physical reason for it to happen, and palaeoclimate evidence suggests that the climate sensitivity (warming in response to heating, such as by CO2) is within the IPCC range (Rohling et al., 2012).

    Perhaps the palaeoclimate studies caught some of the slow positive feedbacks like Arctic methane release and therefore are hiding shorter term negative feedbacks like changes in circulation but this seems a stretch given the agreement between sensitivity during different epochs when the longer term feedbacks should be different because the climate setup was different.

    Even if we get permanent La Ninas, is that enough to stop warming forever? I'm not sure of any studies of this, but using the top graph from Tom @79 we might just end up on the La Nina trend line. So we'd have a one-time drop of 0.1-0.3 C which would 'hide' a decade or two of warming, then we'd be back on the same warming trend.

  38. IPCC model global warming projections have done much better than you think

    How AGW will affect ENSO is unknown, with theories for both more La Nina and more El Nino. It would take decades to test any theory. However, if you look at the John Neilson-gammon graph, you will slope of warming curve for La Nina years pretty much parallel to main trend. If there was no more El Nino say, then you would show a flat trend (when drawing from a previous El Nino to current La Nina) for a little while, then warming trend would continue as before. Delaying climate action due to betting on no more El Ninos would seem a bad strategy. The current run of La Nina-neutral doesnt look much out of historical normal if you look at the long term values of the index.

  39. Lawson, Climate Change and the Power of Wishful Thinking

    The BBC are clearly violating the letter and spirit of the report by Professor Steve Jones a couple of year ago which explicitly warned against a specious "equal time" for minority views in science. Jones has publicly pointed this out, and he is not the only one.

    According to John Ashton, formerly the top climate-change official at the Foreign Office, the BBC's coverage of last week's report from the Intergovernmental Panel on Climate Change was "a betrayal of the editorial professionalism on which the BBC's reputation has been built over generations".... He questions why a senior corporation figure had long meetings about climate change with Nigel Lawson and Peter Lilley, both prominent UK sceptics. His criticism was echoed by other green campaigners, and academics

    Guardian on BBC coverage

    I honestly think this is the sort of thing that happens under a Conservative government - Lawson as an old Tory from the Thatcher days has access to levers of power he would not have otherwise under another party. That comes out in some of the denier talking points emanating from government ministers. If it was not for the presence of the British Liberals in the Coalition, Cameron's government (which he boasted would be "the greenest ever") would be tending towards that of Abbott or Harper.

    While left-leaning governments may be hypocritical and tend to "greenwashing", at least they come with less fossil-fuel corporate baggage.

    I am not British, btw, and am centrist by nature and choice, but I will probably never vote for a government of the right ever again - not when you look at Canada & Australia. It is a relief that in Germany the SPD or the Greens may be in government with the CDs.

     

  40. IPCC model global warming projections have done much better than you think

    One more question came to mind.

    If the ENSO is a kind of chaotic-emergent phenomenon that - as Tom clearly showed-

    looks like the basis of the "hiatus", is there any possibility that the frequency of

    ENSO could increase as part of a large scale negative feedback loop to inhibit

    the long term trend?

     

    In other words, if the climate has large scale regulatory properties, of which ENSO

    looks be one and it is inherently unpredictable, then could it (or other processes)

    kick in to dampen the warming trend at some point.

     

    Again, genuinely curious.

     

    cheerss

  41. Lawson, Climate Change and the Power of Wishful Thinking

    It's really simple. Lawson is in influenced strongly by those who pay him to be a public figure. Follow the money and you will find the fossil fuel industry is most likely paying his way. He has little importance in the great scheme if things.

  42. IPCC model global warming projections have done much better than you think

    Tom

    I think that is very important information.

    Obviously it's out there but enhancing its availability/accessibility would be welcomed.

    The deeper science is very difficult to grasp but if there is a logic and a data

    exercise to support it then it makes a great deal of difference. Especially when it

    addresses an emerging critique of AGW.

     

    cheers

  43. IPCC model global warming projections have done much better than you think

    sereniac @70, I mentioned three methods that show the "hiatus" is almost completely the result of ENSO fluctuations.

    The first was first implemented by John Nielsen-Gammon.  He took the simple approahc of removing most of the ENSO influence by grouping years by ENSO status, then seperately taking the trend for each group:

    This approach has the advantage of being intuitively obvious.  If the trends for El Nino years, neutral years and La Nina years are all the same, and there is no hiatus in each category seperately, then any apparent hiatus in the full record is a product of the increased frequency of cool ENSO states (ie, La Ninas) rather than a change in the underlying trend.

    The second approach was taken by Foster and Rahmstorf, who identified the ENSO, volcanic, and solar signals in the temperature record, and removed them.  The result is a good approximation of what the temperature record would show without those natural variations:

    The third, and most interesting, approach is that by Kosaka and Xie (also at SkS, paper linked by scaddenp @76).  They ran a climate model, but constrained the tropical pacific ocean to follow historical temperature patterns, thereby forcing the model to have the actual ENSO history.  Outside of the tropical Pacific, the model determined temperatures in the normal way, only with the historical ENSO influence from the constrained temperatures in the Pacific.  The result was a very close match to the observed temperature record:

    This approach is a little more complicated than the others, but more theoretically interesting.  However, it does demonstrate very directly that (a) current model with historical ENSO patterns and forcings predicts the observed temperature record, "hiatus" and all.

    These three approaches together mean that it is all over bar the shouting as to the dominant cause of the hiatus, IMO.  Scientists, being scientists, continue to explore the issue because, first, there may also be other subsidiary causes, and second, it is worthwhile spending effort trying to knock down obvious explanations (if for no other reason than that is how reputations are made).

  44. IPCC model global warming projections have done much better than you think

    Thanks grindupbaker.  Video is my favourite educational media....

    I think I got a better handle on the issues but I believe it will be a hard sell to

    government if the post 1998 "trend" continues for say 5 more years.

    I think it is very difficult to explain to nonstatisticians that a system has components

    like ENSO which simply "happen" and are unpredictable but the overall system can still be projected into the future within limits that are useful for policy.

    Quantum mechanics has somewhat similar underlying principles. It is inherently statistical although no given quantum is predictable. The difference is that quantum

    tunneling can be shown in the average large screen TV these days.

    thanks for your explanatory efforts.

    All the best

  45. IPCC model global warming projections have done much better than you think

    @sereniac #73 There are numerous lectures on internet video if you are interested such as:

    ---science only---

    David Randall: The Role of Clouds and Water Vapor in Climate Change - Simon Fraser University Kevin Trenberth: The Role of the Oceans in Climate - Simon Fraser University Sarah Gille : Long-term Temperature Change in the Southern Ocean - Perspectives - University of California Television climate modelling lectures by Prof Inez Fung (she has several, they all hurt my brain) Prof Inez Fung: Anatomy of a Climate Model: How Robust are Climate Projections? Professor Ted Shepherd: Understanding uncertainty in climate models

    -- science & activism --

    The Scientific Case for Urgent Action to Limit Climate Change - Richard Somerville Berkeley University: Dan Miller Extreme Climate Change Catastrophic Climate Change & Runaway Global Warming - David Wasdell

    David Wasdell: various

    Richard Muller: various

  46. IPCC model global warming projections have done much better than you think

    http://skepticalscience.com/16_years_faq.html will help fill in the ENSO influence.

    You cant exactly "add" ENSO the models. ENSO-like behaviour emerges from models but it is unpredictable as is the real thing. This is primary reason why models have no skill at decadal-level projection and dont pretend to do so.

    Kosaka and Xie 2013 explore what happens when you impose the actual ENSO on the climate model outputs.

  47. IPCC model global warming projections have done much better than you think

    Me #66 I made a mistake with "how many volcanoes and nuclear weapons exchanges will occur" because these would only reduce temperature noticeably at the date projected by the models if they occurred with a couple of years or so prior. Otherwise, the aerosols would have grounded and surface temperatures would have lowered with no reduction in insolation or greenhouse effect so the following temperature rise would be rapid back to the interim unbalanced-ocean balance point. Would be some slight residual reduction in the warming rate because oceans would have taken less heat than projected by the models due to a couple of years or so of cooling or reduced warming, so they would do the surface hiatus thing for a while. There must be numerous other unpredictable human choices and ad hoc natural events that might or might not happen that make "prediction" an impossibility.

  48. IPCC model global warming projections have done much better than you think

    Sorry the gravity analogy was very poor.

    More like "At what point do we stop searching for gravitons?"

    Given that GR predicts it but no evidence has accumulated so far.

     

    thanks again

  49. IPCC model global warming projections have done much better than you think

    I think I'm getting a sense for this now. (But don't hold your breath).

    My understanding so far is that essentially we would have to refute many known physical laws (boltzman's law etc etc etc) in order to refute the warming hypothesis.

    I also think people are saying from scaddenp's comment that say a 5 year departure

    from the projection envelope would be enough to suggest that although the science is still correct, practical limits in computation/data and other issues may be the reason for it.

    Tom Curtis also mentioned that some commentators have suggested a 17-22 span of very low trends would imply the models (although not necessarily the science)

    was in question.

    Is that a fair summary?

    I think it may be an unfair question since in some ways it is like asking "At what point

    do we give up on the theory that gravity applies througout the universe?"

    Thanks again

  50. 2013 SkS Weekly News Roundup #40A

    "How not to write a headline about the IPCC's climate science report" should be pointing to here. It's currently linking to the New Scientist report instead.

    Moderator Response:

    [JH] Link fixed. Thank you for bringing the glitch to our attention.

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