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Chemware at 09:22 AM on 3 August 2010Why I care about climate change
Pretty much the same here, except I'm not a Christian, and I am a scientist working in the area. Have to admit though, I really love driving thebrand new top-of-the-line BMW5 year old Yaris that I bought on all thatgrant moneyhire-purchase. -
Mystyk at 09:14 AM on 3 August 2010Why I care about climate change
Eloquent, thoughtful post. Kudos. I share the same sentiment as your first reason. I depart from you on your second. As a humanist, I simply look at the world as a place where we all have to live, and therefore all are its stewards. This requires a certain level of responsibility on the part of all of us, regardless of the status of any higher authority. As you also said, we will all draw our own reasons. I have found, much to my dismay, that I can far too easily get drawn into an XKCD-approved SIWOTI defense, for example. I would therefore only add one more critical reason as I interpret: the defense of truth for the sake of its value as truth. Striving to not be wrong is its own reward, if done with integrity and humility. -
Tony O at 09:13 AM on 3 August 2010Why I care about climate change
Here, here, agreed. If you have faith does not that faith require stewardship? So much of the climate change argument is about averages, put weather back into those averages and it gets scary. What will the extremes be like? -
NewYorkJ at 09:12 AM on 3 August 2010Has Global Warming Stopped?
The statistical significance argument is also of limited value when you're dealing with a variety of indicators. The Jones example just refers to one - the HadCrut analysis. There is also the GISS and NOAA analysis, which (correct me if I'm wrong) reaches the 95% confidence level over the same time period. Now these aren't entirely independent. Then there is satellite data, which is mostly independent. I believe these reach similar levels of confidence as HadCrut over this time period. Not to mention that HadCrut neglects the Arctic. http://www.woodfortrees.org/plot/hadcrut3vgl/from:1995/to/trend/plot/gistemp/from:1995/to/offset:-0.09/trend/plot/rss/from:1995/to/offset:0.15/trend/plot/uah/from:1995/to/offset:0.15/trend Then we have the rapid melting of global glaciers and ice sheets observed over this period, along with a notable increase in ocean heat content. The existence of independent indicators is important. If I wanted to analyze the assertion that a slot machine has a net negative expected value for the player, I could observe a single player, accumulating a significant number of rounds, observing a downward trend in his bankroll, and reaching a 90% confidence level. Pretty good, but what if we include 3 other players, let them play the same number of rounds, and they reach 90-95% confidence also with a similar downward trend. Wouldn't true confidence be higher when such independent observations are combined? Not a precise analogy, I know. -
Deech56 at 09:08 AM on 3 August 2010Why I care about climate change
And in doing so you are also standing up for science. You go about this in the best way - using the scientific literature to support your arguments. People can look up the information themselves. -
chris at 09:07 AM on 3 August 2010Visually depicting the disconnect between climate scientists, media and the public
Poptech at 03:51 AM on 3 August, 2010 Poptech at 08:48 AM on 3 August, 2010 As robhon has pointed out "quality" certainly isn't subjective. The assessment of “quality” is made in relation to specific criteria, but these criteria can be objectively defined (they may have fuzzy edges!), especially so for science (and why bring "modern art" into it!?). Here’s a relevant real world example: At the moment the entire UK academic research community is gearing up to the latest of its periodic “research assessment exercises (“RAE”; though this is now called “REF”!). This is an assessment of a department's research quality and is not a notional exercise; the results of REF determine how major elements of government funding are allocated to Universities; REF matters and it matters a lot. How is research quality assessed? A major element is the quality of publications. Each and every research-active researcher in every scientific department in every University in the UK will be submitting their “best” four publications for the period (start 2008 to end 2011). How is the “quality” of a paper assessed? This can be done reasonably objectively in two ways. Scientific journals are ranked within subjects according to their impact factor (average # of times papers in that journal are cited within 2 or 3 years of publication; other defined criteria can be used); papers that have been in print sufficiently long can be assessed in terms of the number of times the specific paper has been cited by others. Each of these is recognised to be an objective measure of research quality (clearly in order to publish a highly cited paper in a good journal I will likely have obtained funding, have done a significant body of research on an important problem and produced a piece of work of high quality). Note that commentaries and reviews don’t count (one can say whatever one likes in a commentary, these are usually not peer reviewed and reviews themselves are not a necessary indicator of research quality). It’s obvious that major elements of UK government funding (and academic and industrial scientific appointments throughout the world) are based on research and publication quality, and that these have definable and objective assessment criteria (even if we may consider that the metrification of quality has gone rather too far). I can understand why you feel the need to downplay what are very obvious real world criteria of research and publication quality. Your odd list of disparate bits and pieces including numerous commentaries in various magazines, duplicated entries and articles that simply don’t correspond to your criterion (“supporting scepticism of man made global warming alarm”) is astonishingly low on quality. That's an objective interpretation based on real world and definable criteria. -
David Horton at 09:01 AM on 3 August 2010Why I care about climate change
I didn't know there was anyone WRONG on the internet John? Who? Where? What? -
David Horton at 08:58 AM on 3 August 2010Has Global Warming Stopped?
As to fydijkstra's graph. In addition to what the others have said, it's worth thinking about what the poster is implying. That we have all been getting hot and bothered over nothing - that we thought we were climbing inexorably up a graph that led to 1 degree, 2 degrees, 6 degrees of warming, when, silly old us, it was just that we were cursed by living in interesting times. That we just happened to be lying on the temporarily upward slope of a polynomial wave graph (and of course that this temporary upward slope just happened to coincide with the rapid increase in CO2 levels being spewed out by the rapid industrialisation of the planet. Pure chance it was, and lucky that the deniers stopped us greenies taking western civilisation back to mud huts. Only the deniers managed to keep their nerve while all around were losing theirs). Trouble is, as with all of this kind of amateur graph reading from the deniers, there is no mechanism presented for explaining how the change in global temperatures could be polynomial rather than linear. Where is the negative feedback that takes CO2 back out of the air once it reaches a a certain concentration? Or, conversely, what is the mechanism that allows CO2 and the greenhouse effect to keep on up and up and up while temperatures go back down down down? Proper science doesn't work post hoc. That is, you need to work out an hypothesis for the climate systems of the planet, then test that against the actual data. You can't simply try to see patterns that apparently emerge from the data after the event. I'm sure we've discussed this before. -
nhthinker at 08:55 AM on 3 August 2010On Consensus
"How about this one" Wallace Broecker concluded: "Our efforts to understand and EVENTUALLY to predict these changes need to be redoubled" Science is about prediction based on mathematical models. Broecker was not claiming he had high confidence in a quantitative model. His paper was much more qualitative in nature. A good model would define a function that twenty years into the future that would contain all the variables needed to make the prediction. Solar variability, CO2 and other GHG, volcanic activity, etc. Then, the twenty years of data is plugged in to see if the model from 20 years in the past can produce a prediction that is 90% accurate. If that can be done for many years without a need to constantly add more factors to the model in order to improve its accuracy, then Climate science will have arrived at the magical 4.5 level of confidence. I predict that will not actually happen for at least another 50 years. In the mean time, over the next twenty years, the IPCC predicts developing nations emissions of CO2 will dwarf current levels and thus allow climate scientists to have increasing amounts of CO2 to better test their climate models. -
Mal Adapted at 08:55 AM on 3 August 2010Has Global Warming Stopped?
Careful with Poptech! He's been suspended from both Deltoid and WUWT for posting personal details about another commenter. -
muoncounter at 08:50 AM on 3 August 2010What's in a trend?
Then #21 should say "every indication that the cool periodis nowshould be upon us. As was pointed out here two years ago, the PDO lacks any long term information about global temperature rise.#22: "I do hope the last few summers here are not representative of a "cooling period"." Same here. If this is cool, hot will be really ugly.
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Doug Bostrom at 08:43 AM on 3 August 2010September 2010 Arctic Ice Extent Handicapping Via ARCUS
Tamino teases the tea leaves, looking at variances between years w/regard to extent versus area versus phasing of changes. Lovely arcana. Also a prediction is ventured, with methods. -
canbanjo at 08:30 AM on 3 August 2010Visually depicting the disconnect between climate scientists, media and the public
Had a sim through the poptech list, noted the publications include: The Electricity Journal New Zealand Geographer Irrigation and Drainage Iron & Steel Technology Nordic Hydrology Bulletin of Canadian Petroleum Geology New Concepts In Global Tectonics Weather ICE - Civil Engineering Hungarian Meteorological Service Monthly Weather Review Energy Policy Economic Affairs Economic Analysis and Policy Energy Fuels Area Social Studies of Science Regulation Journal of Forestry Public Administration Review Journal of Chemical Education Journal of Cosmology The Review of Economics and Statistics Malaria Journal Weather and Forecasting Journal of the American Water Resources Association Leadership and Management in Engineering Environmental Politics Society The Independent Review World Economics New Literary History Quarterly Journal of Austrian Economics Waste Management The Cato Journal Economics Bulletin World Economics Economic Affairs Canadian Journal of Agricultural Economics Arizona Journal of International and Comparative Law and of course E&E -
Dikran Marsupial at 08:30 AM on 3 August 2010Has Global Warming Stopped?
Poptech said: 'Sorry boys 95% is what statistically significant means. Anything less would not be "statistically significant".' My previous post was based on a misunderstanding of what Poptech wrote. In actual fact, the 95% level is merely a convention, a rule of thumb, with no deeper significance. You can claim statistical significance at any level you like (as long as you are clear about it), however nobody will be greatly impressed by a result that is significant at the 50% level of certainty. The 95% level is a sensible default, but it isn't set in stone. Bayesian significance tests also have a similar set of conventional threshold values for the Bayes factor, but likewise they are merely a useful rule of thumb. -
Doug Bostrom at 08:17 AM on 3 August 201010 key climate indicators all point to the same finding: global warming is unmistakable
Stmwatkins, indeed there is the rough equivalent of an Arctic Ice Fantasy League (AIFL, sounds legit!) in play. Not exactly to the level of hulking guys with five-o'clock shadows clutching fistfuls of sweaty money and chomping on stogies while hunched over a pair of dice, but near enough. September 2010 Arctic Ice Extent Handicapping Via ARCUS is one parlor where you can make your bets. Daft it is, at least on an inter-annual basis. Morbidly fascinating, too. -
stmwatkins at 08:07 AM on 3 August 201010 key climate indicators all point to the same finding: global warming is unmistakable
CBDunkerson #125 I would like to change my use of the term skepticism to the term question and state that I have a very conservative science background. It appears that using the term "skeptic" is a bit like waving a red cape around here :) Also, I need to change my current job if I thought computer models were nonsense. My question was about differentiating the anthropogenic forcing from natural forcing, and that appears to be mainly through the GCM's. Like I stated in my initial post, I believe there is a anthropogenic component. My question is how much? Which I am slowly looking into. More to this thread topic. Is there some type of Arctic Sea Ice fantasy league going on? I am very conservative (no s-word used) on AGW issues but this is a bit daft. Increasing Arctic Sea Ice would be a good thing but it does not signify some type of scientific victory one way or the other. -
sidd at 08:00 AM on 3 August 2010The Past and Future of the Greenland Ice Sheet
Re: Tenney Naumer:"Newer studies indicate that the runoff is moving closer to half of the mass balance decline." were you thinking of Broeke et al., Science, Vol. 326. no. 5955, pp. 984 - 986, 2009 "Partitioning Recent Greenland Mass Loss" from the abstract: "The total 2000–2008 mass loss of ~1500 gigatons, equivalent to 0.46 millimeters per year of global sea level rise, is equally split between surface processes (runoff and precipitation) and ice dynamics." Certainly makes me look at Figure 4 from Pffefer above in a whole new light. http://www.sciencemag.org/cgi/content/abstract/326/5955/984 sidd -
kdkd at 07:55 AM on 3 August 2010Visually depicting the disconnect between climate scientists, media and the public
Poptech #43 This LA LA LA I CAN'T HEAR YOU mode of argument is pretty tiresome. 1. As I said, you're welcome to try coming up with a better systematic criterion for expertise. This concept is more important and achievable than objectivity. 2. Again you are confusing your self-appointed expertise with the idea that a systematic procedure if fairly applied across the sample of interest is adequate. Your self-professed expertise on the workings of Google Scholar is irrelevant here. 3. By other measures, E&E is not a good quality journal (e.g. library holdings) - it's actually quite difficult to get hold of, only being held in about 50 libraries. It's also clearly contaminated by the editorial desire to confound research results and political ideology - a kiss of death for a journal focusing on social science. You do seem to enjoy talking around in circles, I suspect it's due to the weakness of your argument, and lack of range of what you will argue about. -
kdkd at 07:43 AM on 3 August 2010Has Global Warming Stopped?
(cont) Also your analysis indulges in a bit of cherry picking. Why not evaluate the linear trend since 1960? The R2 and p value will be pretty high for that too. -
kdkd at 07:41 AM on 3 August 2010Has Global Warming Stopped?
fydijkstra #19 What you're doing there with your polynomial fit is almost certainly something called overfitting. This is where your model is describing the noise component of the relationship rather than the signal. Of course as Dikran points out, the noise could relate to ENSO in this instance. -
Doug Bostrom at 07:18 AM on 3 August 2010Visually 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. -
Dikran Marsupial at 06:39 AM on 3 August 2010Has 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. -
Doug Bostrom at 06:35 AM on 3 August 2010Has 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. -
Dikran Marsupial at 06:28 AM on 3 August 2010Has 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. -
Rob Honeycutt at 06:04 AM on 3 August 2010Has 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. -
fydijkstra at 06:03 AM on 3 August 2010Has 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!
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Dikran Marsupial at 06:00 AM on 3 August 2010Has 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! -
Adam C at 05:51 AM on 3 August 2010Has 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. -
Adam C at 05:49 AM on 3 August 2010Has 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. -
Doug Bostrom at 05:22 AM on 3 August 20101934 - 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 -
johnd at 05:21 AM on 3 August 2010Waste 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. -
Dikran Marsupial at 05:01 AM on 3 August 2010Has 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. -
Doug Bostrom at 04:58 AM on 3 August 2010On 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. -
Albatross at 04:56 AM on 3 August 2010Has 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. -
Rob Honeycutt at 04:55 AM on 3 August 2010Visually 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. -
Ian Forrester at 04:54 AM on 3 August 2010Has 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. -
Geo77 at 04:50 AM on 3 August 2010Has 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. -
actually thoughtful at 04:45 AM on 3 August 2010Has Global Warming Stopped?
Of course it stopped! It has been cloudy and cool at my house all week! -
Doug Bostrom at 04:37 AM on 3 August 2010Waste 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. -
canbanjo at 04:36 AM on 3 August 2010Visually 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 -
dcwarrior at 04:36 AM on 3 August 2010On 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. -
Rob Honeycutt at 04:34 AM on 3 August 2010Visually 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. -
actually thoughtful at 04:30 AM on 3 August 2010On 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. -
dcruzuri at 04:28 AM on 3 August 2010Has 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. -
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. -
Dikran Marsupial at 03:46 AM on 3 August 2010Has 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. -
RSVP at 03:37 AM on 3 August 2010Waste 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. -
JMurphy at 03:16 AM on 3 August 2010Visually 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). -
Alexandre at 03:14 AM on 3 August 2010Has 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? -
Rob Honeycutt at 03:09 AM on 3 August 2010Has 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.
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