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Comments 72501 to 72550:

  1. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    Norman, why is it in your desire to prosecute your agenda (and it is patently obvious you have one) you first frequent the denialist and dissembling websites for ammunition rather than relying upon the science and the scientific method themselves? A hint: The words "Gore 'Lie-A-Thon' " on the top of your linked source should have been a tipoff of bias. And a very typical page at c3. Reliance upon this type of "source" undermines your credibility severely.
  2. Models are unreliable
    A blogger has just posted an objection to climate models that I haven't come across before. Hopefully someone here knows more about it than me. The claim is that: "By concentrating on anomalies they (scientists) hide the fact that the models get the absolute global temperatures wrong by as much as 2C." I was under the impression that temperature anomalies are used because they correlate well over large distances, whereas absolute temperature doesn't. This sounds like the type of argument that McKitrick and Essex might have used. Any ideas, anyone? Thanks, Paul
    Response:

    [DB] "By concentrating on anomalies they (scientists) hide the fact that the models get the absolute global temperatures wrong by as much as 2C."

    The key word in your quote is "hide".  Your blogger is operating under the premise that there is a conspiracy, therefore ____________ is true.  This is a blatant obfuscation, easily proven wrong.

    From the NOAA page:

    1. Why use temperature anomalies (departure from average) and not absolute temperature measurements?

      Absolute estimates of global average surface temperature are difficult to compile for several reasons. Some regions have few temperature measurement stations (e.g., the Sahara Desert) and interpolation must be made over large, data-sparse regions. In mountainous areas, most observations come from the inhabited valleys, so the effect of elevation on a region’s average temperature must be considered as well. For example, a summer month over an area may be cooler than average, both at a mountain top and in a nearby valley, but the absolute temperatures will be quite different at the two locations. The use of anomalies in this case will show that temperatures for both locations were below average.

      Using reference values computed on smaller [more local] scales over the same time period establishes a baseline from which anomalies are calculated. This effectively normalizes the data so they can be compared and combined to more accurately represent temperature patterns with respect to what is normal for different places within a region.

      For these reasons, large-area summaries incorporate anomalies, not the temperature itself. Anomalies more accurately describe climate variability over larger areas than absolute temperatures do, and they give a frame of reference that allows more meaningful comparisons between locations and more accurate calculations of temperature trends.

    NASA has a nice synopsis on models, here.

  3. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    michael sweet @212 It appears someone has already compiled a list of what I have been looking for. This person took extreme weather events from the 1950's, 60's and 70's and put them on a list. I will link you to this webpage and you can see what you make of it. List of some extreme weather events.
  4. Philippe Chantreau at 06:38 AM on 16 October 2011
    Continued Lower Atmosphere Warming
    Of course muon, that's the way it will inevitably be represented by some. There is nothing anyone can do about that. The attentive reader who wants to know will notice that Dr P in fact showed nothing. Sure he showed that there is no warming "trend" since 2002 but also readily acknowledged this was meaningless because no trend, or lack thereof, can be establish over that time period. Then when asked by why he would devote so much attention to a meaningless trend, he was rather evasive. I must say I found that whole exchange rather surprising considering Dr P's background. We had countless occurrences on this site of people arguing about meaningless short term "trends", I recall there were threads devoted to the explanations of why short term says really nothing. I do not remember any respectable scientist with a deep understanding of noisy time series making that same argument.
  5. Visual depictions of Sea Level Rise
    shibui Try this one.
  6. Visual depictions of Sea Level Rise
    According to Steven Goddard at Real Science, the Envisat data is showing a drop in sea levels.Does anybody have any information on this?
  7. Continued Lower Atmosphere Warming
    DM#60: "it is not unreasonable to expect the same from the skeptics" There are 'skeptic' circles with a far shallower understanding of the foundations of this bridge. I'll go out on a limb and make a devil's advocate speculation: In those circles, this exchange will be played as 'Dr. P showed that warming really did stop and they couldn't show that to be false.' Of course, the other hypothesis could be that there will be universal acceptance within the 'skeptic' world that it cannot be proven that warming stopped. Anyone care to give odds on which hypothesis will win out?
  8. Continued Lower Atmosphere Warming
    Dikran, that was a great explanation of power!
  9. Ocean Heat Poised To Come Back And Haunt Us?
    Rob Painting might care to comment on this quotation by Berenyi Peter on a prior thread. It poses an interesting theory about how the overturning is mechanicaly driven: Quote: (-Very long quotation snipped-). unquote I believe the forties and fifties south latitudes are not well measured and therefore the extnt of heat sequestration or loss to space is largely unknown.
    Response:

    [DB] Please provide a link plus an explanation of why it is relevant to this thread.  Long quotations are considered poor etiquette and are frowned upon.  Thanks!

  10. Dikran Marsupial at 01:47 AM on 16 October 2011
    Continued Lower Atmosphere Warming
    Here is another way in which Prof. Pielke could demonstrate that the post-2002 trend is interesting, rather than just a likely artifact from looking at a noisy time series over too short a timespan. Rather than basing the argument on the failure to reject a null hypothesis, he could instead reframe it so that he was arguing for an alternative hypothesis, for instance H1: The rate of warming has diminished since 2002 And then see if he could reject the null hypothesis H0: The rate of warming has remained constant throughout He is then back in the normal statistical hypothesis testing setting, where he has to show that the observed trend is inconsistent with H0. This is straightforward, if you detrend the data, assumung a constant linear trend over the entire time series, H0 can be rejected if the residual trend from 2002-present is statistically negative. Now if we are going to talk about bridge-building, then I would say that I have built my side well over half way. I have listened to Prof. Pielkes argument, but I have seen what I consider to be a fatal flaw. I have pointed out this flaw, and remained patient and civil when my criticism has been repeatedly ignored (which is a rather disprepectful thing to do). I have now explained why the criticism in some detail to show why it is important, and even suggested two ways in which Prof. Pielke could strengthen his argument to the point where I would accept it. The latter certainly goes well beyond duty; the onus was always on Prof. Pielke to test his hypothesis before publicising it, as he himself said. I am deinitely in favour of building bridges with the skeptics, but if the the foundations of the bridge have to be built on the tacit acceptance of scientific arguments that are clearly fundamentally flawed, then the bridge is unlikely to stand for long, even if it can be completed. I doubt any of us here at SkS expect skeptics to accept any argument just because we think it is obvious, and it is not unreasonable to expect the same from the skeptics (a term I view as high praise rather than perjorative).
  11. Eric (skeptic) at 00:21 AM on 16 October 2011
    Continued Lower Atmosphere Warming
    It seems to me that a good way to determine the significance of a trend in a particular portion of a time series is to perform an analysis on the entire length of the series based on an assumed model. The model will prescribe the length of the series needed. The model is based on theories of various phenomena in the physical system being studied, in this case the atmospheric temperatures and their strong dependence on ocean-atmosphere heat exchange in quasi-cycles, in particular ENSO. When the entire time series is analyzed based on the model, the analysis produces an explanation of the variance in the series which can then be used to determine the statistical significance of a trend in a portion of the series. Here's an example: http://www.atmos.berkeley.edu/~jchiang/Class/Fall08/Geog249/Week13/gv91.pdf
  12. Ocean Heat Poised To Come Back And Haunt Us?
    # Heat buried in the deep ocean remains there for hundreds to thousands of years. It is not involved in the heat exchange occurring in shallower layers. # The ocean, as a whole, is still steadily building up heat, so the next warm phase of this natural cycle may drive global temperatures to new record highs (the ocean heat coming back to haunt us). I am having difficulty reconciling the two statements litsted above. Also when you say # The deep ocean warms during these hiatus decades because heat builds up in mid-latitude regions and is quickly funneled downwards. Do you mean the mechanism can be imagined as a giant funnel whereby the warm water is gathered over a large area at the mouth of the funnel and is somehow compressed downward towards the spigot by which it is transported to depth? I see it as some sort of giant hypodermic syringe by which the warm water is injected to depth. Am I right in these assumptions or is there some other mechanism at play.
  13. Dikran Marsupial at 23:41 PM on 15 October 2011
    Continued Lower Atmosphere Warming
    So how could Prof. Pielke estimate the statistical power of the test? There are many ways you could go about this, but this would be my recipe: According to Tamino, temperature time series are well approximated by a linear trend with ARMA(1,1) noise process. The first step would be to detrend the data and estimate the parameters of the ARMA(1,1) noise process (see this article by Tamino and this one). I can then simulate as many synthetic temperature times series as I like, with the expected effect size under the alternative hypothesis (warming has continued at a constant rate throughout the UAH dataset), by adding ARMA(1,1) noise to a linear trend of (IIRC) 0.138 degrees per decade. Next I generate a large number of these, where we know by construction that the null hypothesis is false, and see how often we get a statistically significant trend from 2002-2011. The proportion of trials where we can reject the (false) null hypothesis (zero trend) is an estimate of the statistical power of the test. I very much doubt it will be 0.8 or above, which is the traditional threshold for useful statistical power. Note we should test the significance of the trend assuming ARMA noise, not white noise. We know the data are correlated, so the confidence interval for the OLS trend will be optimistically narrow, which biases the test. This would be my approach, and if Prof. Pielke could demonstrate useful power by an estimate of that nature, then I would be convinced that the "flat trend since 2002" was of genuine scientific interest, rather than just the a random artifact from looking at a noisy signal over too short a period. Unlike me, Tamino is a genuine expert in time series analysis, so he may have a better test, or be able to pick holes in my recipe, I would of course take any critcisim seriously. The ball is in Prof. Pielke's court; if he wants to convince us that the post-2002 trend is interesting, I have set out what he needs to do. If he wants to concede the point and move on, then that also is fine.
  14. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    Joe Romm reports on extreme flooding in Thailand this month and last. It is by far the most expensive flood in Thai history and has resulted in 10% of their rice farms destruction. They are (were?) the largest rice exporter in the world. They often get heavy rain during La Nina, but the current Nina is fairly weak. Joe links to Jeff Masters blog about this flood. Do you eat much rice? The price will rise this year. Maybe this is just another coincidence and the weather has not responded to AGW, or maybe we are looking at the future.
  15. Every Picture Tells A Story
    Since we're talking about pictures telling a story, watch this on the BBC homepage (and apologies if someone already posted it): http://www.bbc.co.uk/news/world-south-asia-15216875 Melting in the Himalayas captured in photographs.
  16. Continued Lower Atmosphere Warming
    53, Ger,
    I have the impression that all models used are equilibrium models...
    And why exactly would you think that? I suggest you read Climate Models: An Assessment of Strengths and Weaknesses (click the Download PDF link to get the full report).
  17. Dikran Marsupial at 20:57 PM on 15 October 2011
    Continued Lower Atmosphere Warming
    Following on from Glen's excellent comment, I'm going to have a go at explaining to a non-technical audience what I was asking for when I asked Prof. Pielke for the statistical power of the test of the hypothesis. Hopefully this will help explain why Prof. Pielke's assertiones relating to short term trends are potentially deeply misleading. This is likely to be quite a long post, so I may have to make it in installments. Statistical Hypotheis Testing Statistical hypothesis testing is a confusing issue to many, so I will start by running through a simple example. The first step is to form an hypothesis. Lets say I have a coin, and you want to determine if the coin is fair (equally likely to fall as heads as it is as tails), or biased (more likely to fall on one side than the other). Let P be the probability of the coin falling as a head. We first construct the alternative hypothesis (H1), which is usually the thing we want to prove (though not in Prof. Pielke's case as we shall see later), which we can write as H1: P is not equal to 1/2 We also need a null hypothesis, H0, which is normally a statement of what we want to disprove. This is usually the opposite of the alternative hypothesis, H0: P is equal to 1/2 The way statistical hypothesis testing works is to observe some data, and then to see how unlikely it is to observe a set of data as "extreme" or "more extreme" than that we actually observed, if the null hypothesis is true. We call this value the p-value. If the p-value is less than some threshold, α, then we conclude that the null hypothesis is unlikely to be true, so we say "we reject the null hypothesis at the 1-α level of significance". Scientists traditionally set α=0.05, which gives the usual "95% level of significance" that people often talk about. If the p-value is higher than α then we conclude that we can't rule out the possibility that the null hypothesis is true, so we say "we fail to reject the null hypothesis at the 1-α level of significance". At this point, I want to make some observations:
    • If we are able to reject H0, that doesn't prove that H1 is true. We haven't evaluated the probability of the observations if we assume that the H1 is true, and that probability might also be very small!
    • If we can't reject H0, that doesn't mean that H1 is false, it just means that we can't rule H0 out, and if we can't rule H0 out, we can hardly claim that H1 is true.
    • The test is not symmetrical, the outcome of the test only depends on H0, H1 doesn't come into the calculation at all. So if we repeat the test and exchange H0 and H1, we won't necessarily obtain the opposite result.
    O.K., so lets have a practical example, say we flip the coin eight times and it comes down heads each time (this ought to make us rather suspicious!). If we assume that the coin is fair, then the probability of observing a head on each flip is 1/2 and as each flip is independent the p-value is given by p = ½ ×½ ×½ ×½ ×½ ×½ ×½ ×½ = 1/256 This is less than α = 0.05, so we say that "the null hypothesis (the coin is fair) is rejected at the 95% level of statistical significance", which is in accord with out expectations. Lets now consider what happens when we only observe one flip of the coin. Our intuition should tell us that in this case there clearly isn't enough data to data to determine whether the coin is fair or not, so lets see what the test tells us. This time, computing the p-value, we get p = ½ This is much greater than α=0.05, so we say that "we fail to reject the null hypothesis at the 95% level of statistical significance". This example demonstrates that a failure to reject H0 does not necessarily imply that H1 is false, it may just be the case that there simply isn't enough evidence to reject H0, and both H0 and H1 remain plausible given what we have observed. So, how can we distinguish between the situation where H0 is true and the situation where H0 is false, but we just don't have enough data to demonstrate that H0 is likely to be false? One thing we can do is to look at... The Statistical Power of the Test The statistical power of a test is the probability that the test will reject H0 if H0 actually is false. Let us assume that the coin actually has a head on both sides so that P=1, in which case we know for a fact that H0 is false. In this extreme case, we will get a head every time we flip the coin, so if we flip it once the p-value will always be p = ½ and we will always fail to reject the null hypothesis, even though it is false, so the statistical power of the test is zero. If we flip it twice, the p-value is p = ½×½=¼ and again we will always fail to reject H0, even though it is false, so the statistical power of the test is still zero. The fact that the statistical power of the test is zero tells us that even though we weren't able to reject H0, it was probably just the case we didn't have enough data, rather than because H1 was false and H0 was true. If we carry on flipping the coin, when we get to six flips that all come down head, the p-value is p=½×½×½×½×½×½× = 1/64 we have now reached a point where the test always rejects H0 when it is false, so the statistical power of the test is now 1. Now this is an extreme case, where P=1 or P=½. If we could have a less biased coin, say P=0.75, it would take more data to be able to reject the H0 when it was false, because in that case you would see tails in the sequence of flips whether the coin was biased (H1) or not (H0). However, that would make the maths more complicated, but is not necessary to get the basic idea of statistical power. In practice, the statistical power of the test depends on (i) the amount of data available, the more data, generally the higher the power; (ii) the expected size of the observed effect if H1 is true, the larger the expected effect size, the higher the power; (iii) the amount of noise masking the expected effect, the more noise, the lower the power of the test. This makes computing the statistical power of the test rather difficult to evaluate, so most scientists ignore it. This is often O.K., provided you are not trying to base an argument on the fact that we fail to reject the null hypothesis, which is exactly what Prof. Pielke is doing, which is why he is required to show that the statistical power of his test is high enough that the failure to reject H0 is meaningful. I asked Prof. Pielke no less than three times to state the statistical power of the test, and he was either unable or unwilling to answer the question, or even engage in a discussion of the subject. I find this highly disturbing behaviour for an experienced scientist. Just looking at the data and seeing the obvious is not a reliable way to conduct science, if the obvious is not confirmed by statistics, perhaps it isn't as obvious as you think. N.B. Bernard J. is also asking Prof. Pielke for the statistical power of the test, which is often written as (1-β), where β is the false-negative rate of the test (α is the false-positive rate). As Prof. Pielke is making an argument based on a failure to reject a null hypothesis, he needs to address this point if he wants the argument to be taken seriously. His failure to address this point is extemely damaging to his position.
  18. Ocean Heat Poised To Come Back And Haunt Us?
    @Rob Painting Hansen presented an image (figure 9b) with the ocean heat uptake (0-700m) in his paper: ACPD 2011 Earth’s Energy Balance and Implications The green line in his figure 9b is from the Levitus-data. The 0-2000 m ocean heat content data are now also available. I used these data to construct the same graph graph for both datasets (700m and 2000 m). When you subtract the ocean heat uptake values of the two datasets, you should get an idea in which period the deeper ocean gains more heat than the upper ocean. A nice wave pattern appears with roughly a decadal pattern: Is this image a visualization of the decadal pattern you're talking about here or am I messing things up?
  19. Continued Lower Atmosphere Warming
    ssn tsi, correlate somewhat http://woodfortrees.org/plot/pmod/normalise/mean:30/plot/sidc-ssn/from:1970/normalise/mean:30
  20. Continued Lower Atmosphere Warming
    With this thread seemingly coming to a close, with the next installment shortly, I would like to thank all the participants for the way in which this has been conducted. It is uncommon that 'on-line' debates actually have anything but a marginal relationship to the true principle of debating. The civility of the tone here is in welcome contrasts to the majority of the AGW Blogosphere. That said, I would like to make a general philosophical observation that is related to this topic in a broad sense. Climate models make predictions of future temperature changes based on assumed GH gas concentration changes. These predictions contain error bands for the predictions which reflect the various uncertainties in the estimate. In particular the limitations that models have had (at least up to now) in predicting variability, sub-decadal changes etc. Climate variability of +/- 0.2 C/decade is typical and since this is also within the range of estimates for underlying trend, certainly decade or less time scales are inappropriate for comparing observations with projections, particularly with reference to atmospheric temps alone, TLT or SAT. So observed temps to date are entirely consistent with expectations of an underlying trend with an overlaid variability. If such a hiatus period persisted for several decades that would be cause for re-evaluation. The statement I made above however is what I would expect any reasonable person in professional person in Climate Science to reasonably agree with, as well as technically educated and well-numerate lay observers/enthusiasts of Climate Science. Such would be the circle of Authors here at SkS and many of the regular posters. However, that does not include 99.99% of the human race. Most people don't have technical educations that let them easily evaluate the sort of information presented her at SkS, Dr Pielke's Blog, RC or even the IPCC. Being able to evaluate the difference or significance between a 10 year trend and a 17 or 30 year trend, let alone a model based trend with 'error bars'; To those familiar with science, an error bar is a margin of accuracy. To most people, an error is something that is incorrect. So when discussing the sorts of issues put here, everyone needs to be aware that the discussion is being carried out in front of an audience of others with wildly varying degrees of technical and numeric literacy. And that is before we delve into the world of those individuals who want, need, to believe that AGW is all wrong. To the commenters here discussion of the 'it hasn't warmed much since xxxx has significance yyyy' variety is a reasonable technical discussion. To many of the lay-public this sounds like someone saying 'It hasn't warmed since xxxx therefore WARMING HAS STOPPED! So much for these AGW theories!' The point I am trying to make is that in puting up comments in a technical discussion, participants need to be aware that their conversation is being read by others who may not 'process' their comments in the way intended by the author. So there is a continuous, demanding requirement to express ideas in ways that cannot be mis-construed by a less technical audience. Our comments can easily mislead just because we do not allow for the knowledge-base of our audience. So when authors here at SkS defend the use of longer time-scales as a basis for looking at trends, they are not simply attempting to ignore the shorter timescale details that may have a relevence in considering the dynamics of short term climate variability questions - a technical discussion. They are also trying to defend against a less technical audience drawing inaccurate conclusions from the comments because they do not understand the numerical details, or because they have an entrenched position where they want to find grounds to reject AGW in-toto and simply want ammunition. Look at the example of Al Gore and his movie. This was aimed at a mass audience who know diddly-squat about climate science. So he shows the Ice Core data with CO2 & Temps tracking each other pretty much in synch but he doesn't highlight the 800 year time-lag. He was aiming this at a mass audience trying to give a generalised, simplified over-view perspective. Then the fact that he didn't highlight the Temp/CO2 time lag (or the Methane signature, Ice Sheet change time lags, variations in dust levels, changes in vegetation patterns, ocean circulation patterns etc) has been taken by some as being evidence of a deception. When in fact it was simply a simplification for general consumption. It is a reality in the hyper-charged world of AGW Politics/Science that there are some groups and individuals who WANT to show AGW as false - hence the D-word applied to them. And they will commonly take comments & statements, whether from the IPCC or a simple blog-post and try to build ammunition from it to distort and mislead others and defend their 'needed' position. This is in contrast to those who may be truely skeptical - with the critical open-mindedness this implies. However the D'ers are all to eager to cloak themselves in the rainment of 'skeptics'. So as a general comment/plea to all participants here. Ask yourself: 'Who is my intended target audience when I make this comment?'. And more importantly, 'Who will be the ACTUAL audience for my comment, intended or otherwise?'. When making a point on a technical issue of statistics or thermodynamics, will my comment be something that can easily be miscontrued by the uninformed, or worse, misrpresented by the malicious well informed. In this technical debate is important. But care and precision with semantics and language is vitally important when the debate is public. And this is the Internet. EVERYTHING is public.
  21. Continued Lower Atmosphere Warming
    Like others, I feel disappointed by this discussion with Dr. Pielke. We all have been taught that if the data are not sufficient to come to any conclusion we should look for more, not just stay there. The reason why one should stubbornly stick to a non statistical significant trend disgregarding the great part of the data (which we have) is beyond me.
  22. Continued Lower Atmosphere Warming
    With a climate system obeying a more or less chaotic model,is the type of statistics applied the correct one? I have the impression that all models used are equilibrium models, on which a kind of perbutration theory is applied, which is assumed to be Gaussian in nature. All the methods in deriving general parameters are based on those assumptions known to hold for stable, equilibrium models. Just saying that one can battle for years to come over a method which is not applicable in this case. What does stand is that CO2 has rissen sharply and sure it will end up into a different environment, probably not one we or any other higher life form can adapt to so quickly (I give the simple single cell forms a good chance to survive)
  23. Pete Dunkelberg at 16:06 PM on 15 October 2011
    The Dai After Tomorrow
    Daniel, Thanks for looking into this! I'm not sure it's cleared up though. I referred to figure 11 (c) which is for 2000-2009, a period we have just lived through. The base period is 1950-1979, also familiar. I would expect the base period for the online PDSI maps at NOAA to be similar. In addition, reading Dai's paper from the top as I did, and seeing his other figures including figure 7, I still have trouble matching fig. 11 (c) to everything else. Perhaps I should ask Dai unless you have another thought. By the way how do you get these diagrams? do you have the paper as html?
    Response:

    [DB] Pete, the versions in the article above are taken directly from HQ versions hosted by UCAR (Dr. Dai works at UCAR).  My assumption is that they were re-worked to be more reflective of the depth of the data available than the pixilated versions in the final paper.  HTH.

  24. Philippe Chantreau at 15:20 PM on 15 October 2011
    Continued Lower Atmosphere Warming
    Dr Pielke, we are not going in circles, you are. I am joining Paul Tremblay on his questions. If the result of a discussion is going to be "it's not that important and we should move on" why do you raise the question in the first place? I believe that some of these were given some attention on your blog, so at the time you must have thought they did have some importance, what has changed? Paul made a summary of various different points that have been given that treatment, I am as eager to know about why they are now unimportant as he is. Perusing through your posts on the threads on which you have participated, I found both that "policy makers have been misled to think that warming should be monotonous year after year" and extreme attention on your part on time periods during which no trend can be established with significance by any statistical means. This latter emphasis on short time "trends" is exactly why policy makers would come to expect that change be monotonous if they read your blog or other "skeptic" outlets. I admit it is rather surprising and confusing. If you're concerned about policy makers' perception of the trend, should you not only focus on trends that are statistically significant?
  25. The Dai After Tomorrow
    Pete, that's a good question. Perusing the paper I find this:
    "We emphasize that quantitative interpretation of the PDSI values shown in Figure 11 requires caution because many of the PDSI values, which are calibrated to the 1950–1979 model climate, are well out of the range for the current climate, based on which the PDSI was designed."
    For reference, here's Figure 11: A description of their methodology:
    "Here monthly PDSI pm and sc PDSI pm were computed using multi-model ensemble-mean monthly data of precipitation, surface air temperature, specific humidity, net radiation, wind speed, and air pressure from 22 coupled climate models participated in the IPCC AR4,128 and used to assess changes in aridity over global land. Thus, these PDSI values may be interpreted as for the multi-model mean climate conditions. As the PDSI is a slow varying variable, the lack of high-frequency variability in the ensemble mean climate is unlikely to induce mean biases. Figure 11 shows the select decadal-mean sc PDSI pm maps from the 1950s to 2090s from the IPCC 20th century (20C3M) and SRES A1B scenario simulations. Results for PDSI pm are similar with slightly larger magnitudes."
    The other graphics you link to, March 2000-March 2009 and August+September of 2011, are of much more limited snapshots in time & reflect actual measurements of PDSI. Hope that's more clear than mud!
  26. steve from brisbane at 14:17 PM on 15 October 2011
    Continued Lower Atmosphere Warming
    Perhaps not directly on topic, but it does get a mention above. I've noticed at his blog (and now here) that Pielke Snr refers from time to time to his concern about biogeochemistry effects of increased CO2, but I can't say that I have ever noticed a succinct summary on his blog (or elsewhere) as to what specifically he is referring to. Ocean acidification obviously springs to mind, but it always seems his meaning is broader. I would be more than happy if he could explain here. I would also be curious as to why, if he considers this alone to be reason to take serious action on CO2 emissions, does he spend an enormous amount of time on disputing the way other climate scientists are measuring or understanding global warming, when that is obviously interpreted by the climate change skeptics as meaning there is too much uncertainty to bother starting serious action to reduce CO2. It always seems to me that only a tiny fraction of his time is devoted to reminding the likes of WUWT readers that he actually thinks CO2 emissions should be reduced. The rest is on criticism which they interpret as meaning there is no need yet for serious action.
  27. Continued Lower Atmosphere Warming
    Allow me to attempt to summarize the state of the TLT discussion at this point. 1) We agree that over very short timeframes, it's possible to select TLT data for which the trend is small. SkS has said this is actually an expected result (see Santer et al. and the influences of ENSO, solar, and aerosols over the past decade). Dr. Pielke has not explicitly agreed with this point (in fact for some reason he seems to oppose trying to determine why the short-term warming has slowed), but does agree that the short-term slowing of the TLT trend tells us absolutely nothing about global warming. 2) Dr. Pielke says
    "the failure to accept a slowing down of the tropospheric warming, which seems so obvious to me, actually prevents a more constructive discussion with the so-called "skeptics"."
    I think this is a fundamentally unscientific position from Dr. Pielke. He seems to believe that we should cherrypick short timeframes which are not statistically significant, and should not try to examine what effect various factors like ENSO have had on temperatures over that short, cherrypicked timeframe, in order to create a "more constructive discussion with the so-called skeptics." Frankly I think this is a rather appalling statement and could not disagree more. We should not lower the quality of our scientific and statistical analysis just to make the "skeptics" happy. We have agreed that TLT warming has slowed recently, but a) the change is not statistically significant and b) there are reasons behind the change That Dr. Pielke admonishes us for noting these two facts disturbs me. As I said, he seems to be advocating an unscientific approach just to make "skeptics" happy. 3) Dr. Pielke has agreed with our criticisms regarding cherrypicking of short-term data; however, I still fail to understand why he has engaged in this type of argument if he agrees it is invalid, unless he believes it will somehow bridge the gap between our "side" (that being the side of accurate scientific and statistical analysis) and the side of the "skeptics" (that apparently being the cherrypicking side). Frankly this discussion has left me in a very confused state.
  28. Review of Rough Winds: Extreme Weather and Climate Change by James Powell
    skywatcher @208 In the Peterson (2008) paper, I am wondering if you could explain figure 16 trend line. There is a monster peak in the early 1980's but the trend line barely goes up for the 5-day maximum and actually goes down for the 1-day precipitation even though this frame is by far the greatest amount of precipitation anomalies. Then in the early 1990's the dip downward is the greatest since 1956 but the trend line is going up. Without an understanding of how this trend line works or what it is showing, I am not sure how the author concludes that preciptiation has been increasing.
  29. Continued Lower Atmosphere Warming
    Pielkesr. Did you determine the (1 − β) values for your short-term TLT calculations? 1) If so, could you inform the thread of the values? 2) If not, why did you not determine these values?
  30. Every Picture Tells A Story
    I dunno, DB, you provide clear evidence that a. Aurora, when mapped as blue, causes snow b. Aurora, when mapped as red, melts Arctic ice thus proving you can have your cake and eat it too. That circumpolar donut looks pretty tasty.
  31. Every Picture Tells A Story
    I must offer up an apology to Gareth at Hot Topic: I unwittingly used a combination of a Rod Stewart Video + Catchy Title for a blog post that Gareth used in a post last year on Tom Yulsman's Mondrian graphic. For the inspiration for this post, I was watching the science video linked above when the Rod Stewart song of the title came on the radio. Good thing it wasn't "The First Cut is the Deepest"...
  32. Pete Dunkelberg at 13:01 PM on 15 October 2011
    The Dai After Tomorrow
    I have a question on Dai's through review of drought. Your figure 1 closely resembles Dai's figure 11 (c). Much of the USA is red or orange. This is a surprise to me. Compare the other PDSI source: http://www.ncdc.noaa.gov/temp-and-precip/drought/historical-palmers.php?index=pdsi&month[]=3&beg_year=2000&end_year=2009&submitted=Submit or http://www.ncdc.noaa.gov/temp-and-precip/drought/historical-palmers.php?index=pdsi&month[]=8&month[]=9&beg_year=2011&end_year=2011&submitted=Submit USA is not so dry after all. This seems more realistic to me. Can you shed any light on this difference?
  33. An exponential increase in CO2 will result in a linear increase in temperature
    This is an easy misconception to make. However, we must look at CO2 as a function of time, which over the long run is strongly concave up. Temperature as a function of time can also be shown to be concave up - rates of change that increase. So 0.18 deg C/decade over the past 35 years can be said to be just the tip of the warming iceberg.
  34. Continued Lower Atmosphere Warming
    Re: pielkesr With all due respect and thanks to our guest here, Dr. Pielke Sr. for his constructive interactions on this thread, there yet exist a number of issues needing elaboration and elucidation. Such as:
    "All one has to do is look at figure [references a statistically insignificant short period of time in the satellite lower troposphere datasets]..."
    and
    "Figure 8 clearly shows the step change after 1998 [again references a statistically insignificant short period of time in the satellite lower troposphere datasets] along with the large warming at higher northern latitudes. You do not need statistics to see the obvious."
    [Emphasis added] Again, a repeated demonstration of the power of visual inspection as a metric of statistical significance in the scientific arena; all in lieu of actual analysis of time-series too short by definition of receiving rigorous statistical analysis of their significance (if any). Given these precedents, let us use our new-found powers of visual inspection to ponder the scientific significance of these: Please note that all four of these time-series involve trends of decades-to-hundreds-of-millennia (all greater than the 30 years minimum standard to be considered climate). It is indeed exceedingly clear that one does not need statistics to see the obvious...
  35. An exponential increase in CO2 will result in a linear increase in temperature
    dagold, [Answer to dagold's question from here.] There are a few answers to your question, each of them playing a part, but I think the biggest answer is simply that warming is not and cannot be expected to be linear. The current rate of warming will increase in some decades, decrease in others, and the final equilibrium temperature of the planet will not necessarily be reached at the same point in time that a doubling is reached... warming will continue beyond that (for how long, it's hard to say)... although, too, since any response to CO2 is logarithmic, in that sense warming will slow, not speed, as we reach a true doubling of atmospheric CO2. Take, for example, the Arctic feedback. As the summer ice melts, the open water absorbs rather than reflects incoming sunlight back into space. At the moment, this feedback is minimal because the system has not gained enough energy to melt Arctic ice by enough, soon enough in the spring/summer months, to have that much effect. When that point is reached, however, and accelerates, we can probably expect even faster warming. In a nutshell, there are a lot of feedbacks that are not simple and linear. Some will occur in steps (like a sudden increased release of methane gas from bogs and oceans) or wait to be triggered at certain tipping points. Some of these may not occur for decades, others perhaps not even for a century (such as the CO2 feedback from a transition of large swaths of the Amazon rainforest, God forbid, to savanna).
  36. Continued Lower Atmosphere Warming
    All - We are going around in cirles on this issue. The parallel to cruise control misses that there are multiple forcings and feedbacks occurring. The "car" is not driving on a simple two dimensional surface. GHG forcing is but oe of a diverse range of human and natural climate forcings. Nonetheless, while we still disagree on a number of issues, I found many of your comments informative. I plan to summarize my conclusion from these discussions later next week. Thnak you again for the opportunity to interact (mostly :-) constructively.
  37. Continued Lower Atmosphere Warming
    I realize this may be off-topic, but I an intensely interested lay person learning as quickly as possible: Muonocounter commented:" The result of that analysis (Tamino's)is the familiar 35 year trend of 0.18 deg C per decade, which seems unshakeable at this point. " My quick calculations of another 85 years to reach 560/CO2 doubling (assuming 2 ppm per year) at 0.18 C per decade yields a total temp increase of approx. 2.3 C for CO2 doubling...why is this below commonly accepted median of 3.0 C for climate sensitivity? Thanks!
    Moderator Response: [Sph] People will gladly answer such questions, but please make some effort to find an appropriate thread using the search box at the top of the page. Many regulars monitor the "Recent Comments" page and so will see and respond to your question where ever you put it.

    You can find my response to your question here, where that post will also give you other relevant information.
  38. Continued Lower Atmosphere Warming
    Dr.Pielke writes: >>You are never going to be successful in building a bridge to those who do not share your viewpoint unless you recognize the value of the other perspectives. You have repeated this admonition a number of times, and it is not helpful in leading to a better understanding of climate science. In essence, you want us to accept your viewpoints just for the sake of agreement. Truth is not arrived at that way. I will repeat what a number of posters have asked for here, what I implied in my very first post: what is the statistical significance of your claim? If there is no statistical significance, then you should not mention it, or admit that it was not prudent to do so. Your other arguments about heat in the ocean may or may not be relevant, but they have little to do with you initial statement. I am also noticing a disturbing pattern from you. You make a controversial claim ("SkS makes ad hominem attacks on Christy," "CO2 forcing is only 28%," "the global average temperature trend in the lower troposphere has been nearly flat"), and then when pressed to substantiate these claims, you claim that the details are not really important to the bigger picture, and we should just move on. If these small details are not important, why raise them to begin with?
  39. Continued Lower Atmosphere Warming
    Dr. Pielke, how can we ever "move on" if you've never bothered to address what this post has been about? That sounds to me like you're asking us to simply ignore the issues that were raised. Here's what you have not answered regarding this SKS post: 1) Why did you select a 13 year period in one of two datasets to make the argument that TLT trend has been flat, when the other dataset disagrees AND the time scale you used probably makes your conclusion statistically insignificant? 2) Why won't you do the trivial work of establishing statistical significance for your claims, claims you've used to criticize a published and peer-reviewed paper? If you can't be bothered to respond to intelligent and careful criticisms of these arguments you're making, it's irresponsible to make them in the first place. This is doubly so since your arguments echo and feed into dishonest tactics used by people who want to avoid dealing with important environmental issues by denying the extent of the problem.
  40. Continued Lower Atmosphere Warming
    Dr Pielke "To say the tropospheric heating has not been less in recent years, is like saying a car is still accelerating with the speedometer says it is at a nearly constant speed over the last few kilometers." I think a car analogy can be useful, but not this one. If you rethink a car being under cruise control, but with the power output being regulated rather than the speed, it's a lot like the climate system being 'driven' by a forcing - in this case CO2 and other GHGs. And we know why cars are not controlled in this way. Because the natural terrain will cause the vehicle to vary its speed. Speeding up and slowing down in various conditions despite the power generated being exactly the same. And that's what we mean when we talk about the climate system, oceans and all, being forced in one direction. Just as a car with constant power will not show constant speed, it will still get the occupants where they're going - even if the terrain is hilly, or twists a lot, or offers fords with flowing water rather than bridges, or gives a bumpy ride over unmade surfaces. And GHGs do the same for the climate system. They will get us where they're driving us. We simply don't have a map detailed enough to tell us exactly when the bumpy rides and the variable speeds will occur nor how long they'll affect our progress. We have to map our terrain as we go. We call it natural variability.
  41. Continued Lower Atmosphere Warming
    Dikran Marsupial/Albatross Well - its time to move to another topic. To argue over whether the warming in the lower troposphere started in 1998 or in 2002 misses the point. All one has to do is look at figure 7 TLT in http://www.ssmi.com/msu/msu_data_description.html. Figure 8 clearly shows the step change after 1998 along with the large warming at higher northern latitudes. You do not need statistics to see the obvious. We all agree the lower troposphere is warmer today than it was in 1979. Lets move on as the comments are starting to deteroriate as they did when I first started to comment on SkS. You are never going to be successful in building a bridge to those who do not share your viewpoint unless you recognize the value of the other perspectives. Finally, Chris G, you write "The vast majority of climate researchers are convinced that reductions of CO2 production improves our future situation more than any other factor." I am not sure where you obtained this information, but can assure you that this is not case, as exemplified by recent co-authored papers I have been involved with; e.g. Pielke Sr., R.A., A. Pitman, D. Niyogi, R. Mahmood, C. McAlpine, F. Hossain, K. Goldewijk, U. Nair, R. Betts, S. Fall, M. Reichstein, P. Kabat, and N. de Noblet-Ducoudré, 2011: Land use/land cover changes and climate: Modeling analysis and observational evidence. Wiley Interdisciplinary Reviews: Climate Change, Invited paper, in press. http://pielkeclimatesci.files.wordpress.com/2011/09/r-369.pdf Pielke Sr., R.A., R. Wilby, D. Niyogi, F. Hossain, K. Dairuku, J. Adegoke, G. Kallos, T. Seastedt, and K. Suding, 2011: Dealing with complexity and extreme events using a bottom-up, resource-based vulnerability perspective. AGU Monograph on Complexity and Extreme Events in Geosciences, in press. http://pielkeclimatesci.files.wordpress.com/2011/05/r-365.pdf McAlpine, C.A., W.F. Laurance, J.G. Ryan, L. Seabrook, J.I. Syktus, A.E. Etter, P.M. Fearnside, P. Dargusch, and R.A. Pielke Sr. 2010: More than CO2: A broader picture for managing climate change and variability to avoid ecosystem collapse. Current Opinion in Environmental Sustainability, 2:334-336, DOI10.1016/j.cosust.2010.10.001. http://pielkeclimatesci.wordpress.com/files/2010/12/r-355.pdf Mahmood, R., R.A. Pielke Sr., K.G. Hubbard, D. Niyogi, G. Bonan, P. Lawrence, B. Baker, R. McNider, C. McAlpine, A. Etter, S. Gameda, B. Qian, A. Carleton, A. Beltran-Przekurat, T. Chase, A.I. Quintanar, J.O. Adegoke, S. Vezhapparambu, G. Conner, S. Asefi, E. Sertel, D.R. Legates, Y. Wu, R. Hale, O.W. Frauenfeld, A. Watts, M. Shepherd, C. Mitra, V.G. Anantharaj, S. Fall,R. Lund, A. Nordfelt, P. Blanken, J. Du, H.-I. Chang, R. Leeper, U.S. Nair, S. Dobler, R. Deo, and J. Syktus, 2010: Impacts of land use land cover change on climate and future research priorities. Bull. Amer. Meteor. Soc., 91, 37–46, DOI: 10.1175/2009BAMS2769.1 http://pielkeclimatesci.wordpress.com/files/2010/02/r-323.pdf Pielke Sr., R., K. Beven, G. Brasseur, J. Calvert, M. Chahine, R. Dickerson, D. Entekhabi, E. Foufoula-Georgiou, H. Gupta, V. Gupta, W. Krajewski, E. Philip Krider, W. K.M. Lau, J. McDonnell, W. Rossow, J. Schaake, J. Smith, S. Sorooshian, and E. Wood, 2009: Climate change: The need to consider human forcings besides greenhouse gases. Eos, Vol. 90, No. 45, 10 November 2009, 413. Copyright (2009) American Geophysical Union. http://pielkeclimatesci.wordpress.com/files/2009/12/r-354.pdf
  42. There is no consensus
    Muon, Any confusion between 'we all agree', 'general agreement' and 'consensus' was unintentional.
  43. There is no consensus
    Jonathon#483: If you want to debate the existence or validity of 'consensus,' then it is critical to set a standard. Do you not see the difference between 'general agreement' and 'we all agree'? For example, there is probably 'general agreement' among regular readers here that the Oregon Petition is a waste of time. However, I would not say 'we all agree' about that.
  44. Continued Lower Atmosphere Warming
    Tom, I originally used 5 years as reported on many sites, but it did not filter out all the noise, particularly solar cycles and ENSO events. Although 5 years is a better choice for looking at how these events affect temperature. Using 11 (or 9) years does not change the results. At some point, all statistics are arbitrary, because we have chosen them for use. I never said this was a "solution," just better than arbitrarily selected a start date for linear regression.
  45. Climate 'Skeptics' are like Galileo
    saltspringson's comment has got to be good for a bingo.
  46. Continued Lower Atmosphere Warming
    Jonathon, you missed my points. Your choice of 120 months for your moving average is an example of the very same arbitrary choice of timing you claimed to have avoided by using a moving average. Why did you choose 120 months (10 years)? Why not 132 (11 years), which might better take out the solar cycle? Why not some other? You have not avoided arbitrary choice of starting years for computing the trends. You must choose the starting and ending years (and therefore all the years in between) across which you compute the trend in moving average. You did exactly that. Why did you choose those particular starting and ending years? Why not some others? Your "solution" of simply using moving averages isn't a solution to the issue you claimed it is.
  47. Continued Lower Atmosphere Warming
    "It amazes me that with the diversity of human climate forcings, the newly recognized higher importance of solar forcing,..." Surely you don't mean the new Ineson et al. where the authors state already in the abstract that there's little change in global average temperature due to solar uv irradiance?
  48. There is no consensus
    Muon, [snip] Is that your only issue here? That I used we all agree instead of general agreement?
    Moderator Response: [Dikran Marsupial] Inflamatory deleted. Please can everyon involved in this discussion return to a more neutral tone. As there is "general agreement" amongst the climatolgists, but they dont all agree then the difference between definitions is substantive. Please, no more word games, no more discussion of climate sensitivity on this thread. Please get back on topic.
  49. Continued Lower Atmosphere Warming
    Wow, Dr.Pielke, if you'll bear with a novice here and forget my last two posts. Would you agree to the statement that "While it tells us nothing about the future, nor the reasons for increased warming, that from 2006 to now lower tropospheric warming has essentially resumed, at what appears to be a much faster pace than the 30 year trend? And please correct me if I'm wrong!
  50. Continued Lower Atmosphere Warming
    Tom, I mentioned that it was a 120-month (10-year) moving average, and is centered around the dates mentioned. The nice thing about employing a moving average, is that one does not need to choose the timing. This shown in the earlier posts depending on the starting year for computing trends. If you object to using the change in the moving average, then the maximum value occurred in July, 2002 (a local maxima occurred in July, 2005, but it did not exceed the earlier maxima). Hence, any trend starting in 2002 is likely to show a temperature decline. In fact, any trendline starting after Jan, 1997 (with the exception of the La Nina '99) shows a slightly negative trend (although not significantly different from zero).

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