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Comments 113751 to 113800:

113751. Doug Bostrom at 07:18 AM on 3 August 2010
        Visually depicting the disconnect between climate scientists, media and the public
        Oh, brother, I just noticed that the Financial Times piece redlined by The Way Things Break included a quote from none other than Steve Goddard who claims therein that temperature data is "fabricated." So FT's credibility is now on a par with The Register. Nice.
113752. Dikran Marsupial at 06:39 AM on 3 August 2010
        Has Global Warming Stopped?
        fydijkstra, there is however a problem with any purely statistical argument, which is that they ignore existing knowledge. For example, the cause of the apparent flattening is very probably ENSO. So just because a non-linear model gives a better fit (including the additional degrees of freedom) doesn't say anything about the underlying situation. It is entirely possible that a linear model works rather well after the effects of ENSO have been filtered out. In that case, there is still no evidence that (anthropogenic) global warming has stopped, just that it has been temporarily obscured by the effect of the (quasi-cyclic) ENSO.
113753. Doug Bostrom at 06:35 AM on 3 August 2010
        Has Global Warming Stopped?
        Useful perspective, more informative in some ways than a linear trend IMHO fydijkstra, but why do you then spin it with "This trend clearly shows a flattening of the warming trend, if not the beginning of a decline" when "flat" only pertains to the last two years of the 1960-2009 graph by imaginative squinting and no decline is visible? Why introduce the term "decline" when no such decline is visible? More generally, it's acknowledged that a monotonic rise is not a feature we're going to see, which is why a linear treatment is in some ways better for looking at this problem. Even if we could successfully imagine the extension of fydijkstra's graph and could see a decline we'd not be surprised. Jones was speaking of specific claims in any case.
113754. Dikran Marsupial at 06:28 AM on 3 August 2010
        Has Global Warming Stopped?
        I would say "There has been no statistically significant warming since 2008 [if I had performed the test of course], however the statistical power of a test over such a short period would be so low that the results of such a test would be essentially meaningless." I would of course also be happy to explain what "statistical power" meant and other caveats about statistical hypothesis testing as required. However, the first thing I would do is give a direct answer to a direct question. Note it is entirely plausible that most climatologists have better things to do than read climate blogs, and hence may not have been that familiar with the sort of misunderstandings propagated via blogs rather than the journals.
113755. Rob Honeycutt at 06:04 AM on 3 August 2010
        Has Global Warming Stopped?
        Dikran Marsupial... I disagree. I could ask the question as: Do you agree that from 2008 to the present there has been no statistically significant warming? How would you answer that question? "Well, stupid, that's only two years. Of course there was no statistically significant warming." The formation of the question is the heart of the issue. Due to the noise level of climate you would not EXPECT to see statistical significance achieved in that time frame. It has almost nothing to do with the amount of warming. It has everything to do with the noise to signal ratio. So, rather than falling for the trap the questioner had obviously set it would have been more beneficial to point out the trap rather than stepping in it.
113756. fydijkstra at 06:03 AM on 3 August 2010
        Has Global Warming Stopped?
        This analysis is correct, as far as linear trends are considered. The linear trend for 1995-2009 has an r2-value of 0.2269, which corresponds (for 15-2=13 degrees of freedom) to a significance of about 92%. However, if global warming has stopped or weakened, we do not talk about linear trends. Breaking down a 50-year trend into arbitrarily chosen 15-year intervals is not a technique that any serious statistician would apply. If the warming trend has flattened or reversed, we should look for non-linear trends. A convenient tool available in Excel is the polynomial function. Application of a fourth degree polynomial function to the trend for 1995-2009 gives the following picture.
        This trend shows a clear decline, with r2=0.4115. The significance of this trend is 99%, much higher than Phil Jones’ linear trend. Application of a polynomial function to the trend for 1960-2009 gives the following picture. .
        The significance of this trend is very high: r2=0.8448. With 48 degrees of freedom, this has a significance of 99.9% or more. This trend clearly shows a flattening of the warming trend, if not the beginning of a decline. Saturation functions are much more probable in natural processes than linear functions. Every natural scientist knows, that linear trends never continue ad infinitum!
113757. Dikran Marsupial at 06:00 AM on 3 August 2010
        Has Global Warming Stopped?
        As an aside, Paul the octopus provides a good example of the problems with tests of statistical significance. Paul apparently predicted the results of 10 games in the recent football world cup, with 100% accuracy, but does that mean than Paul actually had some skill? If we simpify by ignoring draws, then just guessing would give a probability of a correct prediction of 1/2, i.e. just like flipping a coin. So we could hypothesise that Paul's true accuracy p > 0.5 (the "alternative hypothesis" H_1), with the null hypothesis (H_0) being that Paul was just guessing, i.e. p = 0.5. The p-value is the probability of the observed results assuming that the null hypothesis is correct, so p(D|H_0) = 0.5^8 = 0.0036. This is less than the usual alpha = 0.5, so we would conclude that Paul has statistically significant skill (at the 99.61% level, no less)! So, does this prove that Paul has skill - of couse not, he's a bloody octopus!!! So why does he pass the test of statistical significance - simple, because of cherry picking. We only know about Paul because he was successful; if you have a large enough pool (sic) of predictors, a few of them are bound to be 100% correct, simply by chance. The reason the test is fooled is because frequentist tests are based on the idea of the frequencies of events in a large number of random replications of an experiment. The test of statistical significance assumes that the predictions were a random sample of predictions made by a large number of "alternate Pauls" (or equivalently the predictions of one Paul for a large number of independent world cups). However, this is not the case, we were only interested in Paul after he had already got four predictions correct, so he isn't a random selection of anything, but a biased choice. The statistical significance of trends likewise assumes some fictitious large population of alternate Earths, of which this one is a random sample (or alternatively the particular period of observation being a random sample from a large set of such periods). However the period in question is nothing of the sort. The "skeptics" only became interested when the significance of the trend suited their argument, and they tend to cherry pick the start date to maximise its value (for instance start dates of 1998 and 2002 are used, but not 2000 for some reason ;o). Again, it isn't a random sample of anything, so the underlying assumptions of the test are invalidated (and hence so it the test). As a Bayesian, I find frequentist significance tests a rather odd (for example, why is the criterion independent of the alternate hypothesis?) and a bit of a minefield, but then Bayesian equivalents are not without their problems either. Admission: I was going to work all that out myself, but I found Wikipedia has done it already!
113758. Adam C at 05:51 AM on 3 August 2010
        Has Global Warming Stopped?
        Well, not quite 100%. >95%, anyway, and poptech will tell you that the 5% confidence level is a long way away from statistical significance.
113759. Adam C at 05:49 AM on 3 August 2010
        Has Global Warming Stopped?
        I'd really like to turn this question around. Dr. Jones's response is the correct answer to a statistical test that is set up with a null hypothesis being no warming, or a slope of zero. According to the variability in the too-short dataset, this null hypothesis cannot be rejected with 95% confidence (only 92%). However, if you want to claim that global warming has stopped, you should really formulate the null hypothesis as continued warming at the prior rate - that is, you should start with a null hypothesis that the slope is equal to 0.101 degrees per decade. In that case, given that the slope from 1995-2009 was 0.116 (larger), there is no evidence that the warming has stopped. If I do a two-tailed test (checking to see whether the slope is simply different than 0.101, in either direction), I get a p-value of 0.40. In other words, I can statistically interpret the data from 1995-2009 in multiple ways: - If I say that there is evidence in this series (all on its own) of a warming trend, I have an 8% chance of being wrong (according to Dr. Jones). - If I say that the evidence shows that the rate of warming has changed (from 0.1 degrees/decade), I have a 60% chance of being wrong. - If I say that there is evidence in this series that the prior warming trend has stopped, I have a 100% chance of being wrong.
113760. Doug Bostrom at 05:22 AM on 3 August 2010
        1934 - hottest year on record
        Further to Broadland's remarks, here's something that just popped up: The year 2010 is now tied with 2007 as the year with the most national extreme heat records--fifteen. There has been one country that has recorded its coldest temperature on record in 2010; see my post last week for a list of the 2010 records. My source for extreme weather records is the excellent book Extreme Weather by Chris Burt. His new updates (not yet published) remove a number of old disputed records. Keep in mind that the matter of determining extreme records is very difficult, and it is often a judgment call as to whether an old record is reliable or not. For example, one of 2007's fifteen extreme hottest temperature records is for the U.S.--the 129°F recorded at Death Valley that year. Most weather record books list 1913 as the year the hottest temperature in the U.S. occurred, when Greenland Ranch in Death Valley hit 134°F. However, as explained in a recent Weatherwise article, that record is questionable, since it occurred during a sandstorm when hot sand may have wedged against the thermometer, artificially inflating the temperature. Mr. Burt's list of 225 countries with extreme heat records includes islands that are not independent countries, such as Puerto Rico and Greenland. Seventy four extreme hottest temperature records have been set in the past ten years (33% of all countries.) For comparison, 14 countries set extreme coldest temperature records over the past ten years (6% of all countries). I thank Mr. Burt and weather record researchers Maximiliano Herrera and Howard Rainford for their assistance identifying this year's new extreme temperature records. Jeff Masters Weather Blog
113761. johnd at 05:21 AM on 3 August 2010
        Waste heat vs greenhouse warming
        CBDunkerson at 20:32 PM, with regards to the 2 hot skewers, what difference would there be in the cooling rate of one hot skewer of mass X compared to two hot skewers each of mass x/2? It appears to me that such comparisons seem to overlook that the mass increases when another object is introduced into the vicinity/equation.
113762. Dikran Marsupial at 05:01 AM on 3 August 2010
        Has Global Warming Stopped?
        Poptech@10 - yes, which is why Prof. Jones was quite happy to explicitly state that the trend was not staitsically significant. But then again, statistical significance becomes meaningless if you cherry pick the start date to get the longest trend that fails to be statistically significant, just as it is meaningless if you cherry pick the start date at 1998 to bias the trend to show cooling. Basically this is because the cherry picking involves performing multiple hypothesis tests and not making the appropriate statistical adjustment to cater for it. BTW, failing to be statistically significant does not mean that a warming trend does not exist, or that it doesn't reflect a real physical process. It doesn't even mean (if it is a frequentist test) that we are 95% confident that the trend is positive. Tests have Type I errors (false positives) and type-II errors (false negatives). The "alpha" mentioned by dcruzuri in 11 refers to type-I errors, there is also a "beta" for type-II errors (retaining the null hypothesis when it is false), known as the "power" of the test (hardly ever mentioned). It should be no surprise if a trend fails to pass a test of statistical significance if the power of the test is very low, perhaps because there is too little data (as Prof. Jones pointed out). Essentially a failed statistical test means "insufficent evidence", nothing more. Easterling and Wehner (2009) is an excellent source of information for this one. They show that the trend is smaller in magnitude than the natural variability due to things like ENSO, and so we should expect to find the occasional decadal (10-20 year) tends that don't show significant warming, or even cooling. These have happened before (as shown above) and also appear in the output of the climate models. Thus is it completely unsurprising that "skeptics" can cherry pick an "inconvenient trend". However it is a specious argument.
113763. Doug Bostrom at 04:58 AM on 3 August 2010
        On Consensus
        Actually Thoughtfull I think of it as something like "unnatural variability." Social scientists are trying to better tease out the effect of the email hacking event and heavy snowfall in some regions last winter. There are not enough numbers to say for sure but it seems to me there are at least some hints of effects from those in the statistics. I also wonder if the publicity around the 2007 Arctic ice anomaly influenced the 2008 numbers. I'm left to imagine the situation may be largely static in terms of trends, something that fits with what scientists have learned of ideology being the gatekeeper controlling integration of information into our worldview.
113764. Albatross at 04:56 AM on 3 August 2010
        Has Global Warming Stopped?
        ABG, Thanks for a interesting and well thought out post. I sadly suspect that your prediction for 2013 will come true-- that is the beauty of cherry-picking short windows in noisy datasets such as the SAT record, once can play that game of deception to the end of time. If I recall correctly, for the data and cherry-picked window in question (i.e., up until 2009 in the HadCRUT data), the warming is statistically significant at the 93% level. Poptech might want to inquire why and how Lindzen chose/cherry-picked this particular start date. I'll help, go here. Those in denial about AGW/ACC might also want to do some research on the meaning of statistical significance before pontificating. It seems that they are only too happy to hear what they wish to hear.
113765. Rob Honeycutt at 04:55 AM on 3 August 2010
        Visually depicting the disconnect between climate scientists, media and the public
        Excellent point canbanjo... If 800 is the numerator (that even being a stretch), what is the denominator? 10,000? 20,000? More? If you ran those numbers I think you'd be pretty close to the 97% and 3% figures again.
113766. Ian Forrester at 04:54 AM on 3 August 2010
        Has Global Warming Stopped?
        Poptech said:

        Sorry boys 95% is what statistically significant means. Anything less would not be "statistically significant".

        So, in your distorted view of reality "warming, but not at 95% significance" means "it's cooling"? No wonder your list of papers is so flawed.
113767. Geo77 at 04:50 AM on 3 August 2010
        Has Global Warming Stopped?
        Thank you for the clear and concise discussion of the statistics behind the controversy. The real problem here is illiteracy with regards to the language of statistics among lay people. That's not hard to understand, I'm very nearly statistically illiterate. If anyone should be brought to task over this brouhaha it is the media outlets asking the question and reporting on the answer. Maybe I'm old fashioned, but if you ask a question and you're pretty darn sure the vast majority of your audience is not going to understand the answer, I think there is an obligation to ask Prof. Jones for a more in depth clarification of what the answer means. To take the answer that most of your audience doesn't understand and turn it into a sensationalist headline that doesn't reflect reality is just abysmal journalism. Unfortunately abysmal journalism seems to be contagious and running rampant through our society these days.
113768. actually thoughtful at 04:45 AM on 3 August 2010
        Has Global Warming Stopped?
        Of course it stopped! It has been cloudy and cool at my house all week!
113769. Doug Bostrom at 04:37 AM on 3 August 2010
        Waste heat vs greenhouse warming
        RSVP, ignoring the nonsense part: Outside of this particular point, the main question is whether global warming is due to GHG vs waste heat. For now it seems according to all the data that GHG overwhelm waste heat on a global average. This may be the case. 169 posts later. Some of us enjoy the journey, others the destination. Maybe even both.
113770. canbanjo at 04:36 AM on 3 August 2010
        Visually depicting the disconnect between climate scientists, media and the public
        Poptech, If you believe in quality, you must be able to identify the most important papers from your list. If it is only a numbers game as you seem to be saying, then pro AGW papers will win hands down. Thanks
113771. dcwarrior at 04:36 AM on 3 August 2010
        On Consensus
        DM at #23 I don't think good and persuasive writing and argument are separate from facts or scientific reasoning. They are an integral and possibly neglected part of it. If a judge, your daughter, your Ph.D review committee or the public has been confused by someone's mis-stating or obfuscation of the facts, simply stating the facts again won't be persuasive in any of those forums. True, any political effort must follow the science rather than the other way around. But simply trying to ignore that you have to write and argue persuasively will just get the pro-science side in more trouble. And, I assume they know your tactics - some of the denier memes may be counting on the fact that you will retreat into "objective" statements of the science in hopes that the public won't be able to tell the difference between their gobbledegook and your science.
113772. Rob Honeycutt at 04:34 AM on 3 August 2010
        Visually depicting the disconnect between climate scientists, media and the public
        Poptech... You've actually ventured into my area of professional expertise here with quality. Quality is NOT subjective. Aesthetics may be subjective, within a range of perception, but even then experts - even in an area as subjective as 20th century abstract art - can readily agree on what constitutes quality. Quality is without doubt quantifiable and measurable. It is measured in a wide ranging number of fields and applications. Quality is NOT a matter of opinion. That is a statement which is beyond absurd.
113773. actually thoughtful at 04:30 AM on 3 August 2010
        On Consensus
        Doug @10 Thanks for the visual depiction. While that information wards off the sense that the battle is lost, it doesn't actually show improved understanding of climate scientists. Over the duration of the graph, the pro-science group (3 left most spheres) lost 4%, while the anti-science group gained 4%). This was during an El Nino event, so the outcomes of the current and future warmings were on display. 70/30 feels comfortable. 66/34 feels much less so (even though it is "only" a 4% swing.
113774. dcruzuri at 04:28 AM on 3 August 2010
        Has Global Warming Stopped?
        Well, let's be very careful about what "statistically significant" means. As I tell my students, one should always state the alpha value when making a claim about statistical significance. Thus, this data is not statistically significant at alpha = 5% (95% level of significance/confidence) but it is at alpha = 10% (90% level of significance/confidence). It may be customary to always set significance at the 95% level, but for absolute precision you should state what it is.
113775. KR at 03:59 AM on 3 August 2010
        Waste heat vs greenhouse warming
        RSVP - Please, please read Roy Spencer's article on Cooler Objects Can Make Warmer Objects Even Warmer Still. If a given amount of energy is going into an object (such as sunlight), cooling to space, it will attain a certain temperature. If a nearby cool object (but warmer than the 3 oK background of space) is present, the heated object will attain a higher temperature. And if you have both GHG and AHF energy going into the atmosphere, the atmosphere will warm more than with only one input - it has to radiate both sources of energy into space. And the ground underneath will warm more as well. There's no 'blocking' of energy involved - that would violate the first law of thermodynamics.
113776. Dikran Marsupial at 03:46 AM on 3 August 2010
        Has Global Warming Stopped?
        robhon@7 The problem with that answer, is that it fails to give a direct answer to the question posed, which is "it is not statistically significant". Failure to answer the question would inevitably lead to an (valid) accusation of being evasive. A scientist should never shrink away from clearly stating the facts, especially when they don't (apear) to support their position. IMHO Prof. Jones provides an excellent example of how a scientist should answer questions, namely directly and honestly. The less scrupulous will twist his words to suit their own purposes, and there is little that can be done to prevent that, but that is an indication of the weakness of their position, not his.
113777. RSVP at 03:37 AM on 3 August 2010
        Waste heat vs greenhouse warming
        CBDunkerson #166 You quote me, "Two hot skewers at the same temperatuere when held next to each other will not warm each other." After reading what you wrote, the above is almost the only thing you wrote that is true. The rest goes into refuting things I havent even said (which you call nonsense), but then when you actually do get back to rewording what I did say, "...since neither gets hotter", you are basically agreeing with me. doug_bostrom #167 Let me answer your question with a made up example. Suppose the temperature on the ground nicely heated by the sun is around 30 C. The air temperature say would be 25 C in the absence of anthropogenic GHG. With 100 ppm more GHG, the temperature instead of 25 is 25.5 C. The point here is you will only get the half degree from GHG if local waste heat isnt also taking the temperature up to 26 C as it is in this made up example. Because you are in the city, waste heat is adding 1 full degree Centigrade. Under these conditions the effect of GHG has been clipped by the waste heat. You dont get 26.5 C (1 from waste heat and .5 from CO2). You only get 26 C. I believe this based on what AGW theory itself says.. that GHGs will take temperatures to a new equilibrium. If an external source is adding heat beyond that equilibrium point, GHG will not be allowed to do this (i.e., "impede the effect of GHGs"). Thus answering your question. The other reason I was saying this is based on what I say in #161 with respect to the Second Law of Thermodynamics. Outside of this particular point, the main question is whether global warming is due to GHG vs waste heat. For now it seems according to all the data that GHG overwhelm waste heat on a global average. This may be the case.
113778. JMurphy at 03:16 AM on 3 August 2010
        Visually depicting the disconnect between climate scientists, media and the public
        Poptech wrote : "My purpose is not to determine which are the top 10 but to provide a resource for peer-reviewed papers that support skepticism of AGW or the negative environmental or economic effects of AGW and to prove that these papers exist contrary to widely held beliefs" No, that is not right. Your purpose was to gather papers from any source (especially from E&E) which YOU believe (despite protests from some of the original authors) "support skepticism of AGW or the negative environmental or economic effects of AGW [ALARM]" - the final word being included in the title to your little list but not, strangely, in the main body describing it (from which your quote comes).
113779. Alexandre at 03:14 AM on 3 August 2010
        Has Global Warming Stopped?
        ABG, In the video (very good one, btw) you mention that the statistic significance is dependent of how many data points there are (among other things). Does the level of confidence change if we use, say, a monthly series instead of plotting just one figure per year?
113780. Rob Honeycutt at 03:09 AM on 3 August 2010
        Has Global Warming Stopped?
        Ian... I always felt that he could have answered that question far better and been absolutely accurate. BBC: Do you agree that from 1995 to the present there has been no statistically significant warming? Fake Phil (me): I calculated the trend from 1995 to 2009 and the warming trend is positive at 0.12C/decade. That time period is too short for where we'd expect to find a statistically significant trend, but even as such it falls at about the 92% confidence level.
        Response: I sometimes reflect on conversations and think, "man, I should've said that". I have to feel for Phil Jones - he gave a bad interview and now has people all over the world saying what he should've said, including myself. Tough crowd.
        
113781. Ian Forrester at 03:01 AM on 3 August 2010
        Has Global Warming Stopped?
        Matt, his answer was perfectly correct and his answer was the only honest and correct answer to a loaded question. The question asked was:

        Do you agree that from 1995 to the present there has been no statistically-significant global warming?

        Phil Jones' complete answer was:

        Yes, but only just. I also calculated the trend for the period 1995 to 2009. This trend (0.12C per decade) is positive, but not significant at the 95% significance level. The positive trend is quite close to the significance level. Achieving statistical significance in scientific terms is much more likely for longer periods, and much less likely for shorter periods.

        The dishonest press and deniers, of course, only quoted the first word of his answer.
113782. Rob Honeycutt at 02:48 AM on 3 August 2010
        Visually depicting the disconnect between climate scientists, media and the public
        Poptech... No, quality is not so subjective as you would wish it to be. This is not a case of beauty being in they eye of the beholder.
113783. Rob Honeycutt at 02:44 AM on 3 August 2010
        Visually depicting the disconnect between climate scientists, media and the public
        I was reading an interesting article the other day about how a "scientist" has just written a paper explaining how light from distant galaxies could reach earth when the earth is only 6000 years old. The "starlight problem" as the creationist community calls it. You can imagine my surprise to find out that the paper is out for peer review. Where? The "Answers Institute." Answers in Genesis. By Poptech's standards, this would constitute a legitimate peer review of legitimate science.
113784. Doug Bostrom at 02:43 AM on 3 August 2010
        Waste heat vs greenhouse warming
        Likewise, waste heat in the atmosphere will impede the effect of GHGs. Following from what?
113785. canbanjo at 02:39 AM on 3 August 2010
        Visually depicting the disconnect between climate scientists, media and the public
        Hi Poptech, If you wanted to educate an uniformed lay person (or scientist for that matter), which are the most important papers from your list which justify/ demonstrate your understanding of AGW? Perhaps a top 10 for starters?
113786. Doug Bostrom at 02:35 AM on 3 August 2010
        Has Global Warming Stopped?
        MattJ, Phil Jones was thinking like a scientist and talking like one. Some in the public arena demand he do so, others demand he tailor his words for rhetorical effect. Someone will be damning him regardless of what he says. Anyway, the meaning of his words was crystal clear to anybody not wearing a contrarian cap. There's a recent interview in New Scientist with Jones. His own stated preference is to resume doing research without being hassled by amateur and professional politicians.
113787. MattJ at 02:32 AM on 3 August 2010
        Has Global Warming Stopped?
        What was Phil Jones thinking? His answer to the BBC was a disastrous failure to adapt his wording to his audience. No wonder the Daily Mail made it a headline interpreting it as "there has been no global warming" Why, even given that Jones was speaking scientific language rather than popularly comprehensible language, his wording is a disastrous mess. What was "no significance at the 95% significance level" supposed to mean? Worse yet, what possible grounds could he have for insisting on 95% instead of the 92.4% we actually got? None! The article is quite right to point out that 92.4% is good enough to show that yes, we do have global warming over the last 15 years.
113788. adelady at 02:25 AM on 3 August 2010
        What's in a trend?
        Hang on, I misread that. 1940 + 60 = 2000. This! is the first complete decade of a cooling period? Personally I'd be really pleased if this was right. But I do hope the last few summers here are not representative of a "cooling period".
113789. JMurphy at 02:25 AM on 3 August 2010
        Visually depicting the disconnect between climate scientists, media and the public
        So, 16% of Poptech's little list can be discounted straightaway, because the relevant papers come from E&E. That's good to know. I have also read lots of other criticisms of that list on so many different blogs, etc. that I reckon less than half are actually valid in any pertinent way. That just leaves the papers that Poptech subjectively reckons are anti-AGW (despite what their own authors say - even after being told by Poptech what their papers actually say !), so not very many.
113790. Doug Bostrom at 02:19 AM on 3 August 2010
        On Consensus
        This comment should be tidied and then upgraded to a blog post; it's a marvelously clear explanation, the double-pendulum employment and graphic beautifully illustrates the difference between weather and climate.
113791. Doug Bostrom at 02:10 AM on 3 August 2010
        1934 - hottest year on record
        I believe you may have missed a point too... the NCDC-NOAA has systematically lowered the early Weather Bureau records. Heavily freighted words. I suppose you'd like us to form some conclusion? Why not say it, or is it more theatrical to leave a decaying, unresolved chord in the dramatic score? These were not single-day records, but monthly records... So what? Put a network of thermometers together, produce a monthly high and low averaged between stations and the same effect I mentioned will apply except more so: most unprecedented and subsequently unparalleled extremes will be found in the earlier history of the network. If there's an overall shift in surface temperature it'll take a while to show up in monthly state-wide records. There's nothing complicated about this. I don't think you understand Meehle's paper, perhaps because you're looking at things through a conspiracy filter. Certainly your failure to understand the expected longitudinal distribution of extremes from a thermometer network suggests you're not very clear on the topic Meehle discusses. Try to be more objective, take the opportunity to learn from Meehle's expertise.
113792. muoncounter at 02:01 AM on 3 August 2010
        What's in a trend?
        #21 "every indication that the cool period is now upon us." What would those indications be?
113793. Rob Honeycutt at 01:51 AM on 3 August 2010
        Visually depicting the disconnect between climate scientists, media and the public
        Poptech... What constitutes a specialist is not subjective at all. I can't randomly perceive someone to be an expert and expect that to be correct. What constitutes as a expert has much more to do with quality and quantity. And for the use of E&E for the majority of your "800 papers." That's tantamount to bottom feeding. It's where scientists go when they can't get published in respected journals. You know this is the case. Even the fact that you absolutely insist that your statements are "100% correct" shows the absurd level you are willing to go to. You exhibit a bizarre megalomaniacal adherence to your own capacity to understand an issue that not even the most eminent scientists in this field would lay claim.
113794. Dikran Marsupial at 01:21 AM on 3 August 2010
        On Consensus
        dcwarrior It is true that rhetoric often has a greater effect on public opinion than science, however it is vital to clearly distinguish between scientific arguments and rhetoric in our responses. If someone makes a specious scientific argument, then it is best answered by a straight scientific response, and that is what SkepticalSciece does so well. What we shouldn't do is respond to specious scientific arguments by engaging in rhetoric ourseves. If we do that we run the risk of being seen as dishonest and lose the trust of the public (and indeed we would deserve to lose it) when our rhetoric is exposed for what it is. Of couse scientists need to understand rhetoric, but (IMHO) only to better advise journalists and politicians to argue for the scientifically justified political and economic action and to expose the flaws in the arguments of the opposition.
113795. adelady at 01:08 AM on 3 August 2010
        Has Global Warming Stopped?
        That video might get a couple of airings with some statistics students. Good stuff.
113796. JMurphy at 01:01 AM on 3 August 2010
        1934 - hottest year on record
        Broadlands, your sources are from 1941 and 1943 - a bit out of date now, don't you think ? If you look at NewYorkJ's comment, you will find more up-to-date and accurate information. From one of the links there, you will find that 1998 was the 'hottest year' in the US, closely followed by 2006, then 1934, 1921, 1999. If you don't trust those figures, that is up to you to explain. Perhaps you should show in what way you believe they have been fiddled somehow. Also, you shouldn't concentrate on daily or monthly maximum temperatures, which are more likely to be the result of local weather - best to concentrate on trends, like this study : The relative increase of record high maximum temperatures compared to record low minimum temperatures in the U.S
113797. adelady at 00:58 AM on 3 August 2010
        Has Global Warming Stopped?
        Based on this very nice bit of work, I s'pose we can predict that warming will keep on stopping - apart from the occasional wild El Nino year. Much appreciated.
113798. dcwarrior at 00:48 AM on 3 August 2010
        On Consensus
        "Science is not about rhetoric, it is about logical argument." Regarding the conduct of science, you are spot on. However, given the population we have now, rhetoric is still necessary to convince the population that they should be concerned about climate change. Blaming science education, while true in a reductionist sense, will not get the results you want. If science wants to win this battle, it needs to understand the tools the opposition is using, VERY EFFECTIVELY, against you. WHY are people being persuaded by a, by all accounts, small group of deniers? They appear to be very politically astute and seem to be pushing people's buttons in a way that they respond. I'm no marketing maven but I know there is science out there on how to persuade people of things - will hard science understand that they need to power of soft science?
113799. Anne-Marie Blackburn at 00:21 AM on 3 August 2010
        Has Global Warming Stopped?
        Good post and what looks like an excellent new resource to fight denialism. Thank you.
113800. Dikran Marsupial at 23:25 PM on 2 August 2010
        On Consensus
        nnthinker said "Not a very good defense". Science is not about rhetoric, it is about logical argument. Casual dismissal of posts intended to be helpful is not an indication of genuine scientific scepticism. Physics can't predict the exact behaviour of a double pendulum because it is chaotic; being able to measure the initial conditions more accurately extends the useful prediction horizon a little, but it doesn't change the fact that a double pendulum is inherently unpredictable. Likewise the weather is inherently unpredictable, and more accurate measurements don't substantially change that, just pushes the useful prediction horizon back a little (for a more advanced treatment, see here). Model predictions are not dependent on temperature records, paleoclimate, thermometer or satelite. They are based on assumptions about climate physics, and simulate the consequence of those assumptions. If you want to show that the models are not accurate, then you need to show that the error of the models is larger than the internal variability of the climate. However, we can't measure the variability of the climate, no matter how good our instuments are, as there is only one stochastic realisation of true climate physics available (i.e. the observed climate on Earth). The best estimate we can get is the spread of the model ensemble, so we are back to the consistency argument again. Note if the climate models were perfect, the spread of the model runs would be a perfect characterisation of the internal variability. So any attempt to discuss the accuracy of the models without reference to the inherent uncertainty is fundamentally misguided. "You claim climate science is about making accurate LONG term predictions. These predictions need some accuracy to them in order to be useful as science." Yes, but we only know if they are accurate in hindsight, and we can only assess the accuracy of hindcasts with respect to the inherent uncertainty of the observations (not just the measurement error, but the uncertainty due to "weather noise"). Can you demonstrate that current climate models give inaccurate hindcasts (or forecasts of long term trends for older models)? "What is your iconic climate model prediction that has proven accurate by the test of time? When was that prediction made?" How about this one "Is that climate model still in use?" Of couse not. Steam locomotives are still capable of pulling carriages, but are no longer used due to a sequence of incremental improvements mean we can now do better. Climate models are no different, but the basic principles uesd now are the same as they were 30 years ago. "Disequilibrium" is indeed an odd term, and a bit of a non-sequitur as nobody mentioned it. The climate spends most of its time in a state of approximate, but not exact equilibrium, with the occasional flip between glacial and interglacial (equilibrium) states. "There is no real objective evidence that warmer is not better." It is the fact that there will be change that is the problem, as that will require adaption, which has economic and societal costs associated with it. If you live in Amsterdam or Bangladesh, you might argue that there is obvious evidence that warmer is not better, at least for you. "How do you think we should plan to stop China and the rest of the developing countries from using coal and burning wood? War? " Does that affect the science or whether the models are accurate? No. HTH (Hope That Helps) Dikran

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