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Comments 64451 to 64500:

  1. Crux of a Core, Part 1b
    Once someone uses the term "alarmist" and brings Al Gore into the discussion, they are pretty much exposing themselves.

    Hall apparently didn't read Alley's comment at DotEarth regarding point #1, since he doesn't address this:

    "First off, no single temperature record from anywhere can prove or disprove global warming, because the temperature is a local record, and one site is not the whole world. One of the lessons drawn from comparing Greenland to Antarctica and many other places is that some of the temperature changes (the ice-age cycling) are very widespread and shared among most records, but other of the temperature changes (sometimes called millennial, or abrupt, or Younger-Dryas-type) are antiphased between Greenland and the south, and still other temperature changes may be unrelated between different places (one anomalously cold year in Greenland does not tell you the temperature anomaly in Australia or Peru). After scientists have done the hard work of working out these relations, it is possible to use one ice-core record to represent broader regions IF you restrict consideration to the parts that are widely coherent, so it is O.K. to plot a smoothed version of an Antarctic temperature record against CO2 over long times and discuss the relation as if it is global, but a lot of background is required."

    Seems the details of this could be expanded on in another post.

    One interesting part of Hall's "rebuttal" is he changes the timescale by an order of magnitude from 10,000 years (his original post) to 100,000 years, so the goalposts shifted quite a bit. It's impossible to note any correlation from the graph over the last 10,000 years.

    Hall also claims Vostok shows the Younger Dryas event, but remove the artificial scaling done on his doctored graph, temperature change is magnified considerably. And did he shift the x axis as well?
    Moderator Response: [Daniel Bailey] "Seems the details of this could be expanded on in another post. " This is in the works.
  2. Roy Spencer’s Great Blunder, Part 2
    nigelj @30: I think the key to understanding his meaning is to look at his recent "challenge to the climate research community".
    Studies that have suggested that an increase in the total output of the sun cannot be blamed, do not count…the sun is an external driver. I’m talking about natural, internal variability.

    Indeed, his focus on "natural" variability excluding the sun keeps popping up in his writings, at least on the blog. More specifically I think he often means "natural variability" to refer to his causality-backwards idea that cloud cover drives mutli-decade climate trends.
  3. Roy Spencer’s Great Blunder, Part 2
    Arkadiusz Semczyszak #32,

    I have on occasions heard Professor Mike Lockwood being quoted as a supporter of the "solar theory" of climate change. This is a distortion of his position. While he believes that sun influences the jet stream and the Northern Hemisphere climate, he is in no doubt that the earth is warming due to CO2.

    You can read this paper:

    Solar change and climate: an update in the light of the current exceptional solar minimum

    Quote
    " In the case of climate change, there is no doubt that global mean temperatures have risen, so that the effect is known to be real. Furthermore, there is a viable explanation of that effect, given that the amplification of radiative forcing by trace GHG increases by a factor of about 2 is reproduced by global coupled ocean–atmosphere models. What is alarming is that in the face of this strong scientific evidence, some Internet sources with otherwise good reputations for accurate reporting can still give credence to ideas that are of no scientific merit. These are then readily relayed by other irresponsible parts of the media, and the public gain a fully incorrect impression of the status of the scientific debate. "
  4. Crux of a Core, Part 1b
    Hall's original thread had comments on it to the same effect, pointing out the regional nature of the GISP2 data and the mistake in dating. One wonders why Anthony Watts doesn't comment on these basic mistakes made by his guest commentators, like an [Editor's Note: ...] sort of thing. This same vein of goof-up happened after Hall's original post when Don Easterbrook made similar mistakes (and sometimes to a more egregious extent), even when the comments for Hall's thread had pointed out the dating error. One might also wonder why Watts uses such non-experts as guest posters in the first place. It doesn't certainly doesn't seem to serve the aim of spreading accurate climate science information to the public. Quite the opposite: I've had to correct mistakes about GISP2 data in more than one place after a guest post on WUWT mangled it. And I'm not even a scientist.
  5. Crux of a Core, Part 1b
    "There are reasons that we look to the top experts in various fields. They are the people who have a deep understanding of the areas of science on which they are commenting. I am quite confident that Dr Hall commands great respect in his own field. I would never presume to denigrate Dr Hall on matters of nanotechnology, AI or microprocessor design. But with all due respect, expertise in one field does not make one an expert in all fields of science. This is made abundantly clear in Dr Hall's original article, as well as his rebuttal."

    We see too much of this; e.g. Freeman Dyson and others. This paragraph sums it up very succinctly and accurately and should be posted in bold on the home page of this website for future reference and use. It should also be tattooed on the foreheads of any number of "skeptics" e.g. Inhofe, et al. Great post!
  6. Crux of a Core, Part 1b
    A Commenter at WUWT suggested that there should be more "rebuttals" of Skeptical Science. I too would love to see them engage in such a scientific debate rather than do as the site owner does and cast insults at the site and it's content. SS does exactly what these people have asked for and scientifically and robustly deals with their so-called counter evidence to which they seemingly can respond only with taunts and ad hom. I invite anyone to compare the two sites, the content and the commentary objectively and decide for themselves which genuinely engages in real, scientific debate.
  7. Climate Sensitivity: The Skeptic Endgame
    "statistics of results":
    If you are questioning the reliability of the models themselves, see the thread Models are unreliable. Models that tend to reproduce observations to date have a built-in check on how far their results can be 'from reality.' An ensemble of such models can then be used to describe 'likelihoods.' Throwing the words 'complex systems' at it doesn't change the basic approach.

    So that argument goes nowhere fast.
  8. Dikran Marsupial at 07:14 AM on 3 March 2011
    Prudent Risk
    RSVP@25 No, apparently several species are effectively biologically immortal, but that doesn't mean they cannot be killed by injury, predation or disease. However, this digression is way off topic, I suggest it ends here.
  9. Climate Sensitivity: The Skeptic Endgame
    46 Giles
    because I think that real scientists should be much more cautious when they do this kind of "statistics of results"

    Just out of interest, who are you suggesting is not a real scientists?
    Here and there we see many critiques of 'scientists' ranging from the accusation of not sticking with some very out of date, potted version of 1930's philosophy of scientific methodology; through the imaginings of people who haven't worked some data from an instrument to a numerical result since school; to out right slander.
    Of course the same techniques - I guess we're talking monticarlo simulation in this case - can be used by 'real' scientists and charlatans; well or poorly in either case...

    So, just who are you accusing of being what?
    And, while we're at it - will you hold your self up to higher standards on SkS... because most people who post here maintain really quite professional attitudes.
  10. Prudent Risk
    #24
    "we would not survive as a species if we lived forever, so your argument isn't even logically consistent. "

    If a species were able to live forever, I think it could also assume it is surviving quite well.
  11. Rob Honeycutt at 06:45 AM on 3 March 2011
    Crux of a Core, Part 1 - addressing J Storrs Hall
    Charlie A @ 42... No. That is exactly what my article is about. Conflating a local record with a global record.

    I state in the very first paragraph, "Using a single ice core record as a proxy for global temperature is a little like reading the thermometer on your back porch and claiming you know the global average temperature."
  12. Rob Honeycutt at 06:42 AM on 3 March 2011
    Crux of a Core, Part 1 - addressing J Storrs Hall
    Charlie A @ 40... I have to say you are quibbling over an extremely tiny point that has no bearing on the overall statements made in the article. I can go back and create a new screenshot of the chart. When I did the original screenshot I was merely trying to make the chart larger and clearer for the reader. No one is challenging the source of the data. It's the GISP2 data from Alley 2000. Hall says so, and I agree.

    You also have to realize there are hundreds of versions of this same chart floating around the internet.
  13. Crux of a Core, Part 1 - addressing J Storrs Hall
    The WUWT presentation tries to make the argument that 'global warming' is unprecedented by using a local curve. Whether they identify as such or not still calls into question the entire methodology. You can semantically scrutinize the above as much as you like, and it is possible to argue (fairly enough) that the author is false to presume that the originators tried to hide it's local nature.

    But inspite of all that it is very hard to prove much with one local proxy - and much of the discussion has produced graphs that demonstrate a far more convoluted local/global relationship (e.g fig 3, from the article). This both shows a far more robust array of evidence, and suggests strongly that the current warming trend isn't the usual holocene pattern. Perhaps more importantly it puts current global temperatures against a far broader spatial variety of data curves - which has a greater overall validity. Honeycutt's primary point seems to be that the overall trend is down - by 1 - 2 degrees over the last 10 K years - but that has largely been arrested in a single century or so.

    tbh I find much of the argument about what was said about wuwt to be strictly secondary, but addressing their methodologies less so. Another example is the forsight.org article here which appears to suffer from a distinct lack of present sight - as it seeks to use the curve to cast doubt upon gw theory with the ice core data, without including any data from the period that global warming is said to have occurred. Small gesures are made along the lines of 'it went up .5 of a degree more', which is not consistent with temeprature records from that area. These kinds of techniques are far more salient an issue than whether or not the above article is wrong to suggest a lack of transparency on the part of these third parties.

    To me the above article was more serving to give a wider context for the GISP2 curve. Sure the sniping is probably misplaced - but I don't think, judging from the concluding dot points - that it was really it's primary intent.
  14. Climate Sensitivity: The Skeptic Endgame
    Inconvenient Skeptic (#17),

    I think a core problem with your line of reasoning is that each argument presumes there must be one forcing of global temperature change, and if there lacks a correlation during a period for that particular forcing, then such a forcing must have little effect on climate. You've applied this logic to both atmospheric CO2 and solar variation. One must look at all causes, which includes volcanic and manmade aerosols.

    Anthropogenic Global Cooling

    Note also that some of the short-term spikes, such as the early 1940's or 1998, can be caused by ENSO variation, so we should look at longer term data.
  15. No Illusions podcast interview (and elocution lessons from an 11 year old)
    You might get more hits on your website if you have her read the next podcast.
  16. Crux of a Core, Part 1 - addressing J Storrs Hall
    70rn, your comments about splicing a global instrumental record onto a single point ice core record are valid. That discussion is the result of a comment.

    That's not what this Skeptical Science article is about.

    Please go back up to the top of this page and read what Rob Honeycutt wrote.
  17. Climate Sensitivity: The Skeptic Endgame
    IPCC scenarios are basically grossly overestimating the size of fossil resources, especially oil and gas. And that "current path" is simply untenable, so extrapolations aren't justified.


    Then it's really time to panic and go to renewables, I guess ...

    Of course, the grownups know this isn't true. Oil sands and natural gas fracking are putting large amounts of previously unavailable fossil fuel into the economy.

    And "peak oil" says nothing about coal, which is available in copious quantities.
  18. Climate Sensitivity: The Skeptic Endgame
    Giles,

    I wonder if you are confused with the "5 to 95% uncertainty" description in the graphs and what that means.
  19. Climate Sensitivity: The Skeptic Endgame
    As I've said Giles, if you want to argue that every single independent line of evidence is somehow biased high, you're free to do so. However, studies based on accurate measurements, such as responses to recent large volcanic eruptions (as discussed in the "climate sensitivity is low" rebuttal linked in the article), are also consistent with the lower bound and range being discussed here. So frankly I don't really think your criticisms are valid.
  20. Crux of a Core, Part 1 - addressing J Storrs Hall
    I think you are totally missing the point in regards to people concerns regarding the above wuwt curve. It seems apparent that the 'instrumental record' displayed isn't data from the local site, or even the Greenland ice sheet as a whole (which has warmed 2 to 3 degrees over the past century); but appears to be a rather abstracted version of the global record as a whole.

    Whilst you may argue, with a degree of legitimacy, that the global temperature been used for comparison before, this in no way detracts from the fact that it's use on a strictly local curve is highly spurious. Especially when other, much more relevant, data is available, and particularly especially when that data shows a far greater degree of parity with any temperature spikes over the past 10K years since the last glacial period (and before that as well, for obvious reasons).

    Using a global average to compare with a specific local site is never robust - in most cases all it demonstrates is misleading at best, flat out fallacious at worst. That you make plain that those demostrating this are clearly aware of the data's purely localized nature, only serves to cast doubt on the agenda of such a presentation.
  21. Climate Sensitivity: The Skeptic Endgame
    dana, I'm making the point that the use of "likelihood", based on a set of widely inaccurate measurements, is inappropriate. So, yes, I'm disputing the fact that " climate sensitivity is very unlikely to be below 1.5°C for 2xCO2", because I think that real scientists should be much more cautious when they do this kind of "statistics of results". And I explain why : if you do a statistics of results of numerical simulations of many complex systems, the result can be very far from reality.
  22. Climate Sensitivity: The Skeptic Endgame
    Giles #44 - I think the problem is that I don't see the point you're trying to make. You don't seem to dispute that climate sensitivity is very unlikely to be below 1.5°C for 2xCO2, correct? If your argument is just that the possible range of climate sensitivity values is wide, that's fine (Annan and Hargreaves would disagree with you), but most of the uncertainty is on the high end.

    Perhaps you could clarify exactly what point you're trying to make here.
  23. Climate Sensitivity: The Skeptic Endgame
    going back to the initial topics
    Dana : "You are of course free to disagree, but as shown in the article, the conclusion that climate sensitivity is unlikely below 2°C and very unlikely below 1.5°C is supported by virtually every study on the subject using both empirical observational data and climate models."

    I don't disagree with this assertion - after all, this is just a kind of demographic study of models and measurements. I'm just saying that the interval of models and measurement is pretty wide, much much wider than what is usually considered as an "accurate" measurement in physical science, and that a demography of inaccurate measurements is not a very solid thing in science to measure a "likelihood" of anything - I gave precise examples in other fields, that is you believe in computer simulations, it is "very unlikely" that the sun oscillates or supernovae explode.
  24. Climate Sensitivity: The Skeptic Endgame
    "making absurd claims to hijack everyone's attention and divert the subject of the discussion is what defines a troll, isn't it?"

    It may be, but my experience is that it is also often defined by "somebody who asks some damned irritating questions that I can't answer". You asked me for some references, did you read them?
    Moderator Response: [DB] Please see the response to you at 41 above.
  25. Daniel Bailey at 04:42 AM on 3 March 2011
    A Swift Kick in the Ice
    For the curious:
    "Data released March 1, 20011 by NOAA’s National Snow and Ice Data Center shows that the seasonal extant of Arctic sea ice at the end of February, 2011, stood at a record low, well below the prior record set in 2005 and almost 3 million square kilometers below the average for that winter date, when sea ice is usually within days of its greatest seasonal extant for the year."
    Pretty much a new minimum maximum (say that 3 times fast):


    Gray line indicates 1979 to 2000 average extent

    I'd say that's a swift kick in the...ice.

    [ -Edit: fixed dates per guidance from michael sweet below; thanks michael! ]

    The Yooper
  26. Climate Sensitivity: The Skeptic Endgame
    Daniel #37

    That crossed my mind too. BTW, making absurd claims to hijack everyone's attention and divert the subject of the discussion is what defines a troll, isn't it?
    Moderator Response: [DB] Everyone deserves the benefit of doubt. Until proven otherwise, Gilles should be considered a guest and seeker after knowledge here. :)
  27. Climate Sensitivity: The Skeptic Endgame
    Daniel , thank you for noticing my contributions to RC - this is not a coincidence. Now you're free to answer my remarks, of course.
    Dana :


    you're confusing "scattering factor" with 95% confidence range. We are 95% confident that climate sensitivity lies above about 1.2°C. As KR #35 noted, almost all of the uncertainty you refer to is on the high end. So all you're arguing is that we can't rule out a scenario where the results of business-as-usual could be really, really bad. However, as I also previously discussed, Annan and Hargreaves put the sensitivity upper bound at 4.5°C with 95% confidence. If you believe their results, climate sensitivity is quite well-constrained."

    As I said, this kind of reasoning, applied to other problems, would conclude with a very high confidence level that solar cycles don't exist and supernovae don't explode.

    "
    Giles #32 - as Albatross noted (#34), unless you want to argue that we have far less coal reserves than we currently believe, the "we will run out of fossil fuels" argument is totally unrealistic. And Alexandre noted in #33, if that is the case, we'd darn well better start transitioning off of fossil fuels ASAP."


    So, if coal resources are reliable, so are oil resources, and you're also claiming that it is very unlikely that oil production would peak before all SRES scenarios predictions ?

    I think that's an interesting point that will be tested in the near future. How much are you ready to bet that oil production will exceed 100 Mbl/d , as all SRES scenarios predicted? I'm interested.

    But of course, I agree that we should try replacing fossil fuels ASAP - I'm just not really sure it is feasible.

    "
    I've addressed your point B previously by showing that the benefits of reducing carbon emissions outweigh the costs several times over. Technically I suppose you're right that it's an argument "skeptics" could make. Perhaps I should have specified "plausible" arguments."

    The real cost is not the cost of replacing fossil fuels by something else. It is in preventing the use of the spare fossil fuels for somebody else -especially the poorest people who need them the most. How far can you justify that fossil fuels should never be extracted even if poor people are starving juste on the above ground? that's not a virtual question, the development of China has pulled hundreds of million of people out of absolute poverty - but to my knowledge it has been achieved only through the use of fossil fuels.
    Moderator Response: [Daniel Bailey] Time to establish some ground rules, then. Let me first start by saying Welcome to Skeptical Science! There is an immense amount of reference material discussed here and it can be a bit difficult at first to find an answer to your questions. That's why we recommend that Newcomers, Start Here and then learn The Big Picture. I also recommend watching this video on why CO2 is the biggest climate control knob in Earth's history. Further general questions can usually be be answered by first using the Search function in the upper left of every Skeptical Science page to see if there is already a post on it. Or you can search by Taxonomy. If you still have questions, use the Search function located in the upper left of every page here at Skeptical Science and post your question on the most pertinent thread. Remember to frame your question in compliance with the Comments Policy and lastly, to use the Preview function below the comment box to ensure that any html tags you're using work properly. Keep the framing of your comments narrow and specific to the thread you post them on. Gish Gallops are frowned upon. Thanks!
  28. Crux of a Core, Part 1 - addressing J Storrs Hall

    The above is from WUWT.
    Note the "Central Greenland: caption in the upper right.

    Compare with the Skeptical Science version, below:


    Fig. 1: GISP2 as presented on Watts Up With That, conflating a local record with a global record.


    Notice the removal of the "Central Greenland" caption.

    ==================

    Let's move on into the article a couple of paragraphs:
    Rob Honeycutt claims "Hall presents GISP2 as if it were a global record and makes no attempts to clarify that it is not nor does he even hint that he has any inclination that this is the case."

    A simple scan of the article Honeycutt links to,Hockey Stick Observed In NOAA Ice Core Data shows the error of Mr. Honeycutt's statement.

    The data is introduced as "It gives us about as close as we can come to a direct, experimental measurement of temperature at that one spot for the past 50,000 years."
  29. Climate Sensitivity: The Skeptic Endgame
    The Inconvenient Skeptic at 22:14 PM on 2 March, 2011

    You're also ignoring the cooling effect of sulphate aerosols which have a negative radiative forcing. But no, continue cherry picking as much as you like.
  30. Climate Sensitivity: The Skeptic Endgame
    The Inconvenient Skeptic at 17:49 PM on 2 March, 2011 ,

    Include a 12-month smoothing in your graphic please and also answer why you decided to end in 1996 considering the volcanic aerosol loading of the atmosphere in 1992,1993 and 1994 were very important?
  31. Climate Sensitivity: The Skeptic Endgame

    Alexandre and Albatross with pleasure : look towards people of ASPO, such as Aleklett, Laherrère, Rutledge http://www4.tsl.uu.se/~aleklett/powerpoint/20100609_Aleklett_kva.pdf http://rutledge.caltech.edu/ http://aspofrance.viabloga.com/files/JL_IPCCscenarios09.pdf they say all approximately the same : IPCC scenarios are basically grossly overestimating the size of fossil resources, especially oil and gas. And that "current path" is simply untenable, so extrapolations aren't justified. Note that the amount of "official reserves" is not criticized - the only point is just that IPCC doesn't really care of proven reserves, it assumes that expensive, unconventional resources could be extracted at the same pace or even a higher pace than the current conventional ones - which isn't justified by any real facts. If peak oil happens soon, which is more and more likely, then all SRES scenarios will fail on this point. KR : "Looking at that same graph, and at the numbers, you will note that the lower end of the range of 2-4.5°C is very solid, very little chance of the actual values falling below that level - " I disagree with you : unaccurate data and models are never "very solid", even on a statistical point of view. They can be prone to systematic biases. As an example, models of the sun can explain a lot of things, but not the 11-years cycle. That is, if you believe in computer models, they hardly describe activity cycles, and when they do, they are much shorter than expected. The 11-year cycle can be dismissed on a "statistical study" of the models - yet it does exist. In the same way , supernovae never explode in numerical models. That's a pity, but supernovae don't exist in the world of numerical computations. Based on numerical experiments, they are statistically impossible. Yet they do exist. So I am personnally rather reluctant in front of a "set of inaccurate measurements". "You seem to be arguing that natural forcings or feedbacks (outside the ones we know of, or poor measurements? Not clear...) will lead to overestimation?" No, I am talking about other causes than forcings and feedbacks - causes of change that are due to something else, changes in the oceanic circulation, atmospheric convection patterns, and so on - that can lead to a variation of the average temperature without a change of the average forcing.

    Response:

    [dana1981] You are of course free to disagree, but as shown in the article, the conclusion that climate sensitivity is unlikely below 2°C and very unlikely below 1.5°C is supported by virtually every study on the subject using both empirical observational data and climate models.  As mentioned in the article, you're basically arguing for the scenario in which every single line of evidence is wrong, because they're all very consistent on the climate sensitivity lower bound.

  32. Daniel Bailey at 04:15 AM on 3 March 2011
    Climate Sensitivity: The Skeptic Endgame
    Just as an FYI, someone also posting by the name "Gilles" has been clogging up threads over at Real Climate for over a year now. Not saying that this "correlation" means anything.

    In the wake of the Poptech, damorbel and RW1 threads, just wanted to point it out.

    The Yooper
  33. Climate Sensitivity: The Skeptic Endgame
    Giles #31 - you're confusing "scattering factor" with 95% confidence range. We are 95% confident that climate sensitivity lies above about 1.2°C. As KR #35 noted, almost all of the uncertainty you refer to is on the high end. So all you're arguing is that we can't rule out a scenario where the results of business-as-usual could be really, really bad. However, as I also previously discussed, Annan and Hargreaves put the sensitivity upper bound at 4.5°C with 95% confidence. If you believe their results, climate sensitivity is quite well-constrained.

    Giles #32 - as Albatross noted (#34), unless you want to argue that we have far less coal reserves than we currently believe, the "we will run out of fossil fuels" argument is totally unrealistic. And Alexandre noted in #33, if that is the case, we'd darn well better start transitioning off of fossil fuels ASAP.

    I've addressed your point B previously by showing that the benefits of reducing carbon emissions outweigh the costs several times over. Technically I suppose you're right that it's an argument "skeptics" could make. Perhaps I should have specified "plausible" arguments.
  34. Climate Sensitivity: The Skeptic Endgame
    Gilles - "well, on the other hand, simple inspection of the Fig 2 in this post shows a scattering of almost a factor 10 in the estimates. So what's your definition of a 'reasonably well known factor'? "

    Looking at that same graph, and at the numbers, you will note that the lower end of the range of 2-4.5°C is very solid, very little chance of the actual values falling below that level - it would contradict just about all the data we have. We know about alligators near the Arctic circle and the "snowball Earth" - the data sets certain minima on what climate sensitivity could be. The high end is less certain - and I'm not going to take uncertainty indicating very high sensitivities as a good sign.

    There are definitely uncertainties in the data, although I believe you are overstating them - lots of lines of evidence support paleo reconstructions of CO2, solar activity, aerosol levels, temperatures, etc. And there are few issues indeed with Milankovic forcings.

    "The issue I see is that IF natural, unforced variability is important , it will generally lead to overestimate the sensitivity. But excluding an unforced variability is very difficult just because you have no way of knowing if it is unforced or not - so by making the assumption that everything is due to forcings, you will end up with a figure, which will be always biased to high values. "

    I have to seriously disagree. You seem to be arguing that natural forcings or feedbacks (outside the ones we know of, or poor measurements? Not clear...) will lead to overestimation? But that's only true if for each of the studies there is an unaccounted for forcing that adds to the effect. It's just as (un)reasonable to argue that said unmeasured forcings subtract from it. If there are poor measurements, they only widen the range, not bias it.
  35. Climate Sensitivity: The Skeptic Endgame
    Gilles @33,

    We have mountains of coal to burn, mountains. We can easily realize the most optimistic scenarios, all of which bring us very close to +2 C warming, and right now we are following one of the most aggressive trajectories. Please provide evidence from a reliable and reputable source that we cannot.

    And even if, in the very unlikely event CS were less than +2 C, consider this:

    1) The impact of ocean acidification on the ocean food web on which a huge portion of the population depends. See appropriate threads (and links) at SkS.
    2) The fact that, on our current path, we will easily double CO2 before 2100. So doubling CO2 becomes arbitrary.

    There are other good reasons for reducing our GHG emissions, but I will leave it there for now.
  36. Climate Sensitivity: The Skeptic Endgame
    Gilles #33

    About this part:

    A) that the amount of fossil fuels that we can really extract is far below most of SRES scenarios and that CO2 levels will never reach dangerous levels anyway.

    Now that's really good news. Can you give me some reference of this and make my day?

    Of course, that makes all the renewable energy stuff even more urgent, but still.
  37. Climate Sensitivity: The Skeptic Endgame
    "Lou - thanks. Agreed, I think "sensitivity is low" will become the go-to "skeptic" argument, because frankly there's just no other way to argue that we shouldn't reduce CO2 emissions. And the refusal to support CO2 emissions reduction measures is the basis for almost all global warming "skepticism"."

    I disagree with that, Dana. There are at least two other possible reasons for arguing that we shouldn't reduce CO2 emissions, even with a 2°C sensitivity.

    A) that the amount of fossil fuels that we can really extract is far below most of SRES scenarios and that CO2 levels will never reach dangerous levels anyway.

    B) that even if some dangers are real, they do not exceed by far the wealth brought by the fossil fuels, and that mitigation is still a better choice. Just as we accept the casualties of car crashes, or a reasonable amount of pollution, or even we do not forbid the sale of alcohol or tobacco.

    Of course, this is not climate science - but it is still relevant to the public debate.
  38. Climate Sensitivity: The Skeptic Endgame
    KR : well , on the other hand, simple inspection of the Fig 2 in this post shows a scattering of almost a factor 10 in the estimates. So what's your definition of a "reasonably well known factor" ? I doubt that any of the paleo records you are citing, that are essentially LOCAL, can give an accurate estimate of the global forcing. Aerosols and clouds are ill known, even now, I doubt very much that they are much well constrained hundreds of thousands of years ago.

    On average, I am not very comfortable with a general feeling of "well, of course, there is much scattering and a lot of unknown factors, but still everything is pretty well constrained".
    The issue I see is that IF natural, unforced variability is important , it will generally lead to overestimate the sensitivity. But excluding an unforced variability is very difficult just because you have no way of knowing if it is unforced or not - so by making the assumption that everything is due to forcings, you will end up with a figure, which will be always biased to high values. Then the statistical analysis of "how many studies show that the figure is above X" will also be biased as well. Is it not kind of an issue ?

    another issue is that the average forcing is by far not enough to define the temperature. During the northern summer, the Earth is farther away from the sun than during the southern summer (orbit ellipticity). But the averaged temperature is higher - because there are more land in the northern hemisphere. So if you take the basic definition of the sensitivity, it is actually NEGATIVE. In principle you could deal with that with averaging over a long period - but then you're facing the problem of possible long term changes in a series of factors (oceanic circulation, land coverage, and so on..).
  39. Climate Sensitivity: The Skeptic Endgame
    Dana, Thanks. Keep at it-- the "skeptics" have nothing but obfuscation and it shows.

    Typo first line , second para (see bolded text below):

    "One of the most pAropular "skeptic" arguments is..."
  40. No Illusions podcast interview (and elocution lessons from an 11 year old)
    Maybe your daughter can give you some interviewing lessons!
    Response: I'm picturing a sequel to "The King's Speech"... "The Blogger's Interview" :-)

    She was obviously buoyed by her speaking skills as last night, she challenged me to a "rematch" where Wendy would interview both of us and the first person to "umm" lost the competition. Unfortunately she won again! I'll be challenging her to a 3rd contest tonight - can't let an 11 year old get the better of me!
  41. Climate Sensitivity: The Skeptic Endgame
    Lou - thanks. Agreed, I think "sensitivity is low" will become the go-to "skeptic" argument, because frankly there's just no other way to argue that we shouldn't reduce CO2 emissions. And the refusal to support CO2 emissions reduction measures is the basis for almost all global warming "skepticism".
  42. Climate Sensitivity: The Skeptic Endgame
    Very nice article, and, as always on SkS, the comment section is "interesting".

    My guess is that we'll be seeing much more of this argument that sensitivity is conveniently (for the deniers) low. The simple fact is that as real world events and scientific advances keep piling up not just evidence that ACC works exactly as we currently understand it, but evidence that's painfully clear to non-experts, the deniers will increasingly fall back on sensitivity. The fact that this argument leads to contradictions among their various positions and that it requires them to come up with other explanations for observed phenomena won't stop them. Such logical issues haven't been a hindrance in the past, after all.
  43. Lars Karlsson at 02:49 AM on 3 March 2011
    Climate Sensitivity: The Skeptic Endgame
    The Inconvenient Skeptic,
    Where do your temperature data in the link from 4 come from? To me, it seems like they have been detrended.
  44. Human CO2 is a tiny % of CO2 emissions
    mikea01, the "IPCC experts" you mention don't actually exist as a body : the IPCC is an aggregation of thousands of scientists and their work. The IPCC Reports are the agreed output of much scientific input, agreed to by not only those who worked on the Reports but also by the vast majority of science and scientists from all branches.
    What is it that confuses you, and which bits (and why) do you consider to be "poor science" ?
  45. Climate Sensitivity: The Skeptic Endgame
    Gilles - Actually, many of the factors are reasonably well known. Ice cores record plenty of information; CO2 levels, aerosols, local temperatures, proxies for solar activity, etc. The Milankovic forcings are tied to orbital dynamics, and those are predictable for millions (if not billions) of years into the past and future.

    I suggest that a look at the Climate Sensitivity is low/How Sensitive is our climate page might be useful. The intermediate version of the page points to a dozen or so separate papers estimating climate sensitivity in various ways, and the advanced version graphically shows the results they got.
  46. Climate Sensitivity: The Skeptic Endgame
    thank you, bern, but this is still a little bit puzzling : how can you measure a sensitivity in the past if many ill-known factors contribute "significantly" to the forcing ?
  47. Arkadiusz Semczyszak at 01:39 AM on 3 March 2011
    Roy Spencer’s Great Blunder, Part 2
    @From Peru
    „I suspect an ideological, right-wing common root on both positions.”

    Such thinking is the road to nowhere. Professor Z. Jaworowski radiologist, and V. Klaus economics professor, in his books "proving" that has Hitler and Stalin were in favor of clean environment - their leftist views formed the basis for the theory of AGW. It's absurd conspiracy theories.

    Skeptics are split into much more than we imagine supporters of AGW. Eg I do not agree with R.S. that is ENSO - PDO (internal climate forcing) decide on changes in cloud cover - and those of the ENSO-PDO (feedback). I agree that determines the nature - the sun (not AGHG), but in a much more complicated - and not chaotic.

    After the publication of the IV report, many papers on AGW supporters - who say they generally agree with the theory of AGW - rebel against allegations that the IPCC models did not appreciate, for example: QBO, volcanic effects on ozone, the effect of ozone on a pair water in the stratosphere and vice versa, lunar cycles, the newly discovered solar cycles, cycles of changes in UV solar magnetic cycles of geo-solar, ENSO impacts on phytoplankton (and vice versa) ..., that the respiration of peat is twice the pandas than estimated in the IPCC report, that are not reflect changes in regional Q10 reduces the actual amount of respiration by 25%, etc.. ...

    Recently for example, Mike Lockwood said that a slight change in the UV (energy - compared to RF CO2) has a huge impact on the jet stream - causes that I am in Poland for 3 weeks I have from 1030 to 1040 hPa and "suffer" from the arctic cold ...

    Though it shows the “feet of clay” and can be based on the great theory of AGW.

    R. Spencer (also R. Pielke) is certainly right in one thing: we know too little about natural climate variability.

    Really about how many regions we can say: “... strong late 20th-century warming (during the warm season) in western North America may have a considerable component of natural climate variability in the signal.”? (Tree rings and past climate in the Arctic, Juday et al., 2010).

    P.S. And evolution has much in common with the climate - for millions of years in practice it was not - occurred only a short time of rapid climate change.
  48. Climate Sensitivity: The Skeptic Endgame
    Gilles at #10: if you look at Dana's Figure 1 in the article, you'll see there are a number of different factors that can influence climate in quite significant ways. There's no reason why all of these should react similarly to Milankovic forcing - indeed, some of them (such as aerosols) are depending entirely on other sources, such as volcanism.

    It's the combination of all these, the total net forcing, that determines how the planetary climate responds to Milankovic forcing. For example, this SkS post explains how the additional CO2 we're dumping into the atmosphere may well over-ride the Milankovic forcing for tens or even hundreds of thousands of years.

    When climate scientists look at how the planetary climate reacted to Milankovic forcing in the past, and try to predict how it will react in the future, they need to take all these other factors into account.
  49. Human CO2 is a tiny % of CO2 emissions
    114 mikea01.
    1/ "experts (or at least those who are knowledgeable about the science) do not agree on very much." you might conclude that if you like, but I'd suggest it's possible to draw another conclusion - there is a high level of consensus in the broad trends, but science always has room for improvement and clearing up details.
    2/ " poor science in many of the arguments" - yes, but most the poor science and, indeed, argumentation, is confined to people motivated not to accept what's going on for one reason or another.

    - on a personal note, your posts contains a chain of assertions and non-sequitors, that I feel it may come under the umbrella of poor-argumentation it's self.

    3/ you might be inclined to go for an "ultimate solution" of population reduction... but most governments would feel that that sounds to much like a "final solution".
    However, on that topic, the best means of getting population growth under control known to man is increasing the standard of living. The only exception to that seems to be the US to a small degree and in extreme cases. Improving wealth, by not using developing countries to dump our pollution in and evening out consumption between the rich and poor is a grand and very difficult strategy, however.
  50. Climate Sensitivity: The Skeptic Endgame
    It seems clear that TIS is cherry-picking data - choosing a period for examining temperature rise that starts in an abnormally warm year (the "1998 of the 50's", looking at the chart) and ending on a moderately cool one. It looks like exactly the same technique used by 'skeptics' to argue there has been no warming since 1998, and by a certain ex-astronaut to argue there's more arctic sea ice than there was 20 years ago...
    Others have touched on the other erroneous assumptions in TIS' posts - assuming that CO2 is the *only* driver of climate, for example.
    But all this is off-topic to this post (apart from the common thread of denying reality)...

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