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

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Comments 104501 to 104550:

  1. How significance tests are misused in climate science
    The real abuse of statistical significance is among deniers who tout statistical insignificance as evidence of something. (See the misunderstanding of Phil Jones' statement on the statistical significance of warming.) No statistically significant result is no result; it is not evidence for the null hypothesis; it is not evidence for anything because statistical insignificance is always achievable with little enough data no matter what is going on. For real evidence that warming has stopped, you want statistically significant evidence that warming is not above a certain rate (let's say .05 degrees per decade). That would be something if that existed.
  2. How significance tests are misused in climate science
    I have to disagree with your application of Bayesian statistics; the scientists should not be bothering with them. When do Bayesian statistics matter? When the prior probability is extreme (very likely or very unlikely). So if the chance of a woman your age has breast cancer is 1 in 1000, and mammograms have a 1 in 100 false positive rate, and you had one done as part of a routine checkup and it came back positive, Bayesian statistics tells us that chances are you don't have cancer. But when your prior probability is something medium, it isn't likely to affect the significance of the result. What's more... just how do you establish the prior probability? By counting planets where the climate sensitivity is above 2 degrees per doubling of CO2 and those where it's below? And if you're already pretty certain that you know what the answer is, what are you adding by doing the experiment? Let's say the existing body of evidence leads you to be 99% certain, and your experiment doesn't cause that figure to budge, do you now show using Bayesian statistics that combining your result with the prior gives you 99% confidence and, presto! a statistically significant publishable result! Of course not. Another problem with this is that it's that prior (is Global Warming real?) which is precisely what we want to figure out, not the "real" posterior (is it really warming at the moment?) We want P(N), not P(N|M). Asking how to get P(N|M) from P(M|N) is getting a few steps ahead -- you also want to know P(M2|N) and P(M3|N) and P(M4|N) and all the other peices of evidence before you do that calculation. And if someone else finds further evidence and publishes a paper showing P(M5|N), well now that Bayesian analysis you did in your paper to get P(N|M1..M4) is out of date. But that calculation of P(M4|N) stands, and will forever be useful as a piece of the evidence used to assess P(N). Bayesian analysis provides a way of thinking about how to combine all the pieces of evidence to form your conclusion, but the proper role of research is to establish those individual pieces of evidence. Establish the symptoms if you will. One experiment is your family history, another the mammogram, another the biopsy. We don't calculate whether the mammogram is positive or negative by considering your family history, rather they stand as separate results which we then combine to make an inference. And in this analogy we can't perfectly do the Bayesian calculation because we don't really know what fraction of the population has cancer, except for what we infer through these tests. But you don't subject patients to tests that tell 1 in 5 healthy people they have cancer, and so likewise we demand statistical significance.
  3. Solving Global Warming - Not Easy, But Not Too Hard
    BP: "Your arguments are getting wilder and wilder." Indeed.
  4. How significance tests are misused in climate science
    Just finished reading the pre pub in JOC and to Dr. Ambaum, a sincere thank you for teaching me something I did not understand well before!
  5. How significance tests are misused in climate science
    Michael Sweet, this particular misinterpretation of statistical significance is not unique to climate science. But the reason folks don't make a big deal out of it is that that misinterpretation rarely has a substantial effect on the decisions of real working scientists--even of scientists who thoroughly believe in that misinterpretation. That's because real, working scientists do not rely nearly so much on those kinds of statistical tests as textbooks and classrooms would lead you to believe. Science is what scientists do. I think Maarten Ambaum's title post at the top of this page agrees:
    In the meantime, we need to live with the fact that “statistically significant” results are not necessarily in any relevant sense significant. This doesn't mean that those results are false or irrelevant. It just means that the significance test does not provide a way of quantifying the validity of some hypothesis. So next time someone shows you a “statistically significant” result, do tell them: “I don't care how low your p-value is. Show me the physics and tell me the size of the effect. Then we can discuss whether your hypothesis makes sense.”
    The big challenge for using Bayesian statistics is choosing the prior probabilities. Bayesian proponents argue that at least that approach forces the decision maker (i.e., scientist) to be explicit about their assumptions. But in practice, most scientists don't bother going through that. Instead they happily rely on the messier and less quantitative but nonetheless completely legitimate approach of treating these non-Bayesian statistical test results as just some pieces of the large body of evidence they use to make their subjectively probabilistic decisions about scientific hypotheses and theories. In doing so, they don't really rely on all the quantitative information that nominally is included in the 5% or whatever percent significance levels. Instead they tend to treat those percentages only as rough indicators of strength of evidence. Consequently, the scientists tend not be be much misled by the incorrectness of those numbers for the particular decisions being made. Scientists use multiple criteria to evaluate theories. See also Tamino's post at Open Mind, on The Power--and Perils--of Statistics.
  6. Climate is chaotic and cannot be predicted
    #14: "It is titled "Chaotic Climate"" Wallace Broecker's work. Perhaps you might be interested in learning that in 1997 he was deeply concerned that atmospheric CO2 was the key trigger of these events: Might the ongoing buildup of greenhouse gases in our atmosphere trigger yet another reorganization of the climate system? Were this to happen a century from now, at a time when we struggle to produce enough food to nourish the projected population of 11 to 16 billion, the consequences could be devastating. ... Clearly, if we are to prepare properly for the consequences of the buildup of CO2 and other greenhouse gases in the atmosphere, we must greatly improve our knowledge of the deep water formation process. To me, it is the Achilles heel of the climate system. ... Everyone would agree that the smaller the CO2 buildup the less the likelihood of dire impacts. But this is old news. In 2008, Broecker was so concerned about increasing atmospheric CO2 as the primary driver of climate change, he was writing extensively about developing CO2 sequestration technologies (see 'Fixing Climate'). A big-scale technological fix for a complex system? Sounds like its not all that chaotic after all.
  7. The science isn't settled
    Martin Vezer's poster from the American Geophysical Union 2009 conference now is available: A Philosophical Defense of the IPCC's AR4 Bayesian Methodology.
  8. The science isn't settled
    Eric (skeptic), what do you think is impossible about expressions such as "I am 100% certain that there are mountains on the moon?" There is nothing "fake" about subjective probabilities. All humans operate on the basis of their subjective probabilities. Click the links inside my comment #12 above. Then read the short essay Probability and Induction: The Very Foundations of Science. For an overview of subjective probability see the New School page on The Concept of Subjective Probability. If you want more detail, here is an article I ran across after a quick internet search: Updating Subjective Probability. It is easy to find a great deal more free material on subjective probability, subjective utility, decision making, and their roles in science.
  9. Keep those PJs on: a La Niña cannot erase decades of warming
    > humanityrules > here's the mean monthly global temperature. No it's not. That's the temperature _anomaly_ chart. You do know the difference? Why don't you try again.
  10. The science isn't settled
    BP, it's easy: "Galileo was 100% certain that there are mountains on the moon." Or "Galileo was 99.9% certain that there are mountains on the moon." Or "I am 99.9999... to so many decimal places of 9s certain that there are mountains on the moon, that for practical purposes I am 100% certain."
  11. How significance tests are misused in climate science
    While the pirate information is entertaining, this post claims that 75% of climate peer reviewed papers use the wrong statistics. I find this a very interesting claim. How could so many people, including skeptical statisticians like Mcintyre overlook this simple mistake? The linked thread by Alden Griffith discusses these type of statistics. He finds only a very small difference in the numbers (92% using Bayesian statistics versus 92.4% using significance tests). Perhaps scientists use significance tests because there is little difference betwen the two and significance tests are easier to do. The post suggests significance tests are not useful, while Griffith seems to suggest there is little difference. Can someone who knows statistics explain how different these analysis really are?
  12. Climate is chaotic and cannot be predicted
    #13 scaddenp I will link you to a Scientific American article (1995). It is titled "Chaotic Climate" and to my surprise it had information that might be of great interest to you. "Cores drilled through several parts of the Greenland ice cap show a series of cold snaps and warm spells, each lasting 1,000 years or more-that raised or lowered the average winter temperature in northern Europe by as much as 10 degrees Celsius over the course of as little as a decade." Talk about Climate Change! Is Climate chaotic? This author believes it is.
  13. Ice-Free Arctic
    Re: Artful Dodger (58) Picked up a copy at Barnes and Noble in Green Bay (mile south of the "frozen tundra" of Lambeau Field). Will try to get on it soon, but am behind in previewing my advance copy of BPL's book on climate change (only half done). The Yooper
  14. Ice-Free Arctic
    #65 CBDunkerson Well in your understanding of the Climate science, do we have 5 years to watch and see? Or are there climate tipping points of no return? I will keep watching the Arctic Ice to see. I am even doing my own research on my own local area (Omaha Nebraska) to see what the data indicates. On a daily basis I log the Daily High/Low temps Log the Normal High/Low temps Calculate the anomaly (I put it on an Excel spread sheet). I log the Record high and Low temps an log the years they took place. I am monitoring the low temps as one of the fingerprints of AGW theory is warmer nights. I was convinced in the 1990's that Global Warming was a quite real (I could walk around in a T-shirt outside in January, temps in the 60's F). It was a climate shift for me from my experience as a child. My memory was of cold and snowy winters. What started my active research on the other side (you call it denier) was when a co-worker told me about how hot it was in the 1930's (from a story about his Father watering cows in the heat). I thought it was just exaggeration of memory until I started to log record high temps for myself and found the 1930's (in the Nebraska and Iowa region) were much hotter than the heating going on in the 1990's. A quick stat. Before 1970 (in Omaha Nebraska) there were 18 record high temps. After 1970 there were 13. The decade of the 1930's had 7 record high temps in January. 1980's had 5 and 2000's had 5. I would agree that the Globe is warming. I am not convinced it is not a natural cycle. I agree AGW does exist. My major question is to the amount. I am still doing active research at this time.
    Moderator Response: Please comment on the relevant threads: Regarding weather in your own geographical area (or anybody else's local geographic area), or short periods of time, see It’s freaking cold!, and 1934 - hottest year on record, and 2009-2010 winter saw record cold spells, and Global temperatures dropped sharply in 2007. Regarding natural cycles, see Climate’s changed before, and It’s a 1500 year cycle, and It cooled mid-century, and It warmed before 1940 when CO2 was low.
  15. Keep those PJs on: a La Niña cannot erase decades of warming
    I thought I'd try see if I could find how the press were reporting this document. I couldn't find anything in the MSM but here's what I could find in some science news sites and others. EurekaAlert ScienceDaily PHYSORG IBT WeatherOnline eScienceNews All of them report the late 2010 cooling to La Nina, none of them assign any of the 2010 warmth to El Nino. Are you happy with this situation Ned?
  16. Keep those PJs on: a La Niña cannot erase decades of warming
    This could get very boring Ned but I re-read the GISS document and I still could not find any statement where they assign any of the warm anomaly in 2010 to the 2009/2010 EL Nino. As I said they are very quick to assign the late year cooling and possible cooler conditions next year to the developing La Nina. Please Ned quote the sentance where you think they do that, I can't find your bolded sentance in the doc. Ned I get that the 1997/1998 El Nino was stronger than the 2009/2010. I get that the impact in 1998 was greater than 2010, I'm not arguing the opposite. That doesn't take away from the fact that the record 2010 temperature are still in part due to the 2009/2010 El Nino. I still believe GISS don't acknowledge that overtly. I just have to take up your description of 2009/2010 El Nino as modest. Modest definition - "limited in extent" The NCAR data seems to show 18-19 El Nino events since 1950. The 2009/2010 El Nino is joint 4th on the basis of peak number. Modest seems an inaccurate definition for the 2009/2010 El Nino. Above average would be better. You see even you are trying to undervalue the influence of the El Nino on 2010's temperature with your choice of words. Ned I agree with you that to some extent this is a perception point. I will admit I'm super critical of things coming out of GISS, I hope though that always remains within the realms of reality. But this is important because we are often arguing on this website in the way the media and others mis-represent the science. I think the take away messages journistist will get from this document is 2010 is warm and 2011-2012 will be cooler because of La Nina, that is an incomplete story. I think you, me and GISS all know that the warm temperature of 2010 where influenced by the 2009/2010 El Nino, the question is why they didn't overtly state that, please provide the quote where you think they do.
  17. How significance tests are misused in climate science
    Re: macoles (11)
    "The travesty, of course, is that we cannot account for the number of pirates empirically measured via apprehension or by sinking of their crafts vs that predicted by Disney movies. Latest measurements of the briny deep suggest some may have fled to Davy Jones' Locker" says the study lead auteur Calypso Cousteau.
     Yo-ho, yo-ho, indeed. The Yo-ho-Yooper
  18. The science isn't settled
    There is a mildly interesting philosophical argument here. By observational evidence and using some basic laws of physics, there are mountains on the moon. That fact cannot be expressed as a probability. Our observations may be wrong along with some basic physics, but that possibility cannot be expressed as a probability. By laws of physics, CO2 causes warming, but it is not "near 100% certain" in any scientific sense but only as a figure of speech. It is an established fact that CO2 and increases in CO2 cause warming unless a lot of physics is wrong. The correctness of the physics cannot be expressed as a probability. There is not a "90% certainty" that manmade GHG is causing "most" of the observed warming. That number is a meaningless invention. There about as much support for the statement that there is a 60% probability that this post will be deleted because it is purely philosophical and philosophy is dangerously close to politics. It is far better to drop the fake probabilities and make statements about theories and supporting lines of evidence. The best evidence is empirical, e.g. http://www.skepticalscience.com/Empirically-observed-fingerprints-of-anthropogenic-global-warming.html Various of these observations and measurements may arguably have alternative explanations. But none of those measurements or counter-arguments have any kind of probability associated with them.
  19. How significance tests are misused in climate science
    Kudos for a fascinating post! Dan
  20. How significance tests are misused in climate science
    Daniel @2 You are fraudulently hiding the incline of the M19CPP (Mid 19th Century Pirate Period) in your graph! All you Pirate Change Alarmists cannot be trusted!
  21. Solving Global Warming - Not Easy, But Not Too Hard
    BP: Your arguments are getting wilder and wilder. Provide a peer reviewed link please. I find it very hard to believe that you seriously think CO2 could be in short supply anytime in the next 1000 years. Where will they get the power to fix all that carbon? Please also provide a link to a functional, full scale thorium reactor.
  22. Berényi Péter at 10:08 AM on 13 November 2010
    The science isn't settled
    #15 Tom Dayton at 01:02 AM on 13 November, 2010 of course Galileo's conclusion of mountains on the moon could be expressed probabilistically OK, give it a try. I'm listening.
  23. Berényi Péter at 10:04 AM on 13 November 2010
    Solving Global Warming - Not Easy, But Not Too Hard
    #125 michael sweet at 08:11 AM on 13 November, 2010 Consequences to plant life? CO2 in short supply? Are you joking? No, I am absolutely serious. Check this Nanotechnology Roadmap out for example, this is how future is manufactured.
  24. Roger A. Wehage at 09:15 AM on 13 November 2010
    Skeptical Science moving into solutions
    #25 Roger A. Wehage at 08:46 AM on 13 November, 2010 Green can happen, as witnessed in Greensburg, KS. Here is a link to the Greensburg, Kansas Recovery Planning website. This might be a good place to start for a few ideas.
  25. Keep those PJs on: a La Niña cannot erase decades of warming
    If you just detrend HadCRUT since 1900 and compare it to PDO+AMO you will see a very close correlation. Right, if you remove the long-term warming trend from CO2, you can then do a pretty good job of predicting the residuals based on a bunch of different oscillations. So?
  26. Roger A. Wehage at 08:46 AM on 13 November 2010
    Skeptical Science moving into solutions
    #24 Berényi Péter at 07:54 AM on 13 November, 2010 There is a name for this political agenda... This has nothing to do with politics; it's about spelling out detailed plans that the average Joe and communities can follow to start the climate change mitigation ball rolling. People and communities don't need more science lectures; they get it. What community leaders and activists need are realistic plans of action that can be adopted or tailored as needed to meet their specific requirements. Working directly with local community leaders and activists is what I mean by starting at the bottom. As "green" communities evolve, other communities will take notice and hopefully follow in their footsteps. Green can happen, as witnessed in Greensburg, KS. There are many websites devoted to Green Communities. I'm not saying that the current state of green community development will fully mitigate climate change, but it certainly may represent a first step. Without that first step, scientists may soon be studying the Odds of Cooking the Grandkids.
  27. Solving Global Warming - Not Easy, But Not Too Hard
    That link for energy ratios should have been: www.hydroquebec.com/sustainable-development/documentation/pdf/options_energetiques/rendement_investissement.pdf
  28. Solving Global Warming - Not Easy, But Not Too Hard
    I have found a more reliable analysis of coal fired electricity generation by the NREL: www.nrel.gov/docs/fy99osti/25119.pdf It uses real world analysis techniques. eg. it takes into account energy inputs to the system. They calculate a net energy ratio that is fractional (0.3), which basically means you get less energy out than you put in. They calculate an average external energy ratio of 5.0 over the power stations life cycle. eg. 5 times more energy out than was put in. This low figure is due to losses such as fuel inputs to get the coal to the power station. Some comparisons of energy ratios here: ww.hydroquebec.com/.../rendement_investissement.pdf Basically, despite coals apparent high energy density, it suffers a great deal from having to be dug up and burnt inefficiently.
  29. Keep those PJs on: a La Niña cannot erase decades of warming
    And why look only at MEI? Since the AMO was in the record highs in the beginning of the year. Combining the effect of these two we have anomalously warm year. @Ned: Well yes, there is a warming trend in the last 15 years. And that is just because nearly all of the warming in the last 30 years happened in a step in the end of 90's. Actually the step would have occurred in the end of 70's if El Chinchon and Mt Pinatubo didnt offset the warming followed from a huge stepwise warming induced by the PDO. And AMO also made a shift back then. If you just detrend HadCRUT since 1900 and compare it to PDO+AMO you will see a very close correlation. Most of the warming in the last 30 years is caused by those (around 60% and 40% might be anthropogenic) so actually there is no recent "acceleration", it is just 30-year weather phenomenoms. And we skeptics are being accused about mixing weather to climate, how ironic is that? Just look at DelSole et al (a recent study) for example, or Thompson et al. Ocean oscillations explain quite a bit from the 20th century warming (and cooling).
  30. Real experts don't know everything
    Norman, then please argue with him directly. On this blog, it sounds like you are arguing with the science which absolutely does not believe we are going to have a runaway greenhouse. (you'd notice scientists at Reaclimate explaining why not).
    Moderator Response: Indeed, this site addresses the argument Positive feedback means runaway warming.
  31. Solving Global Warming - Not Easy, But Not Too Hard
    BP: Consequences to plant life? CO2 in short supply? Are you joking? How am I supposed to reply when your entire response may be facetious. Where would the power to convert limestone to quicklime come from? Oil has already peaked. Coal is estimated to peak in between 25 and 100 years. Gas supply is much less than coal. Perhaps gas clathrates could be tapped but that is not currently economic. In any case, if you waiit another 100 years any fossil fuel will run out and need to be replaced. I am suprised you support solar after your previous posts. Can you provide a link to a working full scale thorium reactor?
  32. Berényi Péter at 07:54 AM on 13 November 2010
    Skeptical Science moving into solutions
    #23 Roger A. Wehage at 06:40 AM on 13 November, 2010 Trying to educate the upper echelon is not working, so the only recourse may be to start at the bottom. Bring in Climate Change Denial Psychologists to learn how to sway the masses. There is a name for this political agenda, but I am not going to stress it here due to comments policy.
  33. Berényi Péter at 07:33 AM on 13 November 2010
    Solving Global Warming - Not Easy, But Not Too Hard
    #123 michael sweet at 03:40 AM on 13 November, 2010 What do you suggest people will do in 200 years when all the oil, gas and coal have been used up? There is no way carbon based geo-fuels could be exhausted on such a short timescale. If they were, large scale conversion of CaCO3 (limestone) into carbon dioxide should be started, as atmospheric CO2 is expected to be in short supply by that time, with detrimental consequences to plant life. The byproduct, CaO (quicklime) by reacting with omnipresent H2O turns into Ca(OH)2 (slack lime). If it gets into the seas somehow, a dangerous ocean basification can occur (milk of lime is a moderately strong base with pH 12.3). Some more advanced geochemistry is clearly needed to neutralize the stuff. In 200 years carbon is supposed to become the default construction material for practically all purposes because of its unique chemical and mechanical properties. Airborne CO2 being the most obvious source (a convenient shortcut for transportation issues), shortage is a real danger indeed in absence of appropriate replenishment. The most likely energy supply is both solar (with photochemical energy capture/storage releasing O2 into the environment with electricity generation on demand in fuel cells using atmospheric O2) and nuclear breeder technology utilizing the thorium cycle.
  34. Roger A. Wehage at 06:40 AM on 13 November 2010
    Skeptical Science moving into solutions
    Trying to educate the upper echelon is not working, so the only recourse may be to start at the bottom. Bring in Climate Change Denial Psychologists to learn how to sway the masses.
  35. How significance tests are misused in climate science
    What physical evidence does global-warming have, other than ice-core samples?
    Moderator Response: This thread is narrowly focused on concepts related to assessing statistical significance.
     
    General discussion of broad categories of evidence for global warming should go in an appropriate thread, such as this or this.
     
    Also, please note that in a series of visits over the past month, you've left at least five versions of the same comment about ice cores, in five different threads. Most of them have now been deleted or redirected here.
     
    Please try to post your comments in the appropriate thread and then stick with them there, rather than spreading discussions across many different threads. This helps make the site more readable for everyone.
  36. Berényi Péter at 05:31 AM on 13 November 2010
    Climate cherry pickers: cooling oceans
    #18 Ken Lambert at 01:38 AM on 13 November, 2010 Dr Trenberth found a theoretical 'observed' 145E20 Joules/year energy imbalance (0.9 W/sq.m) For God's sake! There is no such a thing as "theoretical 'observed' energy imbalance". It is either theoretical or observed. Now, Trenberth 2009 is clear enough.
    1. The observed imbalance is 6.4 W/m2
    2. This observation is inconsistent width model calculations
    3. Therefore observed imbalance is crap, models must be correct
    "There is a TOA imbalance of 6.4 Wm-2 from CERES data and this is outside of the realm of current estimates of global imbalances (Willis et al. 2004; Hansen et al. 2005; Huang 2006) that are expected from observed increases in carbon dioxide and other greenhouse gases in the atmosphere. The TOA energy imbalance can probably be most accurately determined from climate models and is estimated to be 0.85 ±0.15 W m-2 by Hansen et al. (2005) and is supported by estimated recent changes in ocean heat content (Willis et al. 2004; Hansen et al. 2005)." It is non sequitur at its finest. A 6.4 Wm-2 is of course impossible (it happily belongs to the "Had I had three legs it would not have gone unnoticed" category). But from the fact a particular kind of measurement (satellite measured imbalance at TOA) is unreliable, there is no legitimate way to conclude another estimate (quasi-theoretical inference using computational climate models) is correct. The best we can say is it's either correct or not. As it is also inconsistent with ARGO OHC measurements, it suggests ARGO is either crap or not. Trenberth is only willing to consider the former possibility, but the latter one (implying computational climate models are seriously flawed) is a very real possibility at the moment.
  37. How significance tests are misused in climate science
    Thank you Dr Ambaum, I'm sure to use this explication elsewhere. I noticed the fallacy between #2 and #3, but I thought power analysis was going to come into play as a patch (actually, I initially flinched at #3 because the scientist should be thinking that noise + effect is being observed). Typically when one fails to detect a 'significant' effect, one can't accept the null hypothesis but can do a power analysis to determine the strength of effect that he/she should have been able to detect. On the flip side, however, a frequentist wouldn't worry too much if he/she detected a 'significant' effect -- the problem with power only really occurs in one direction. Your post here is about a broader issue than I first thought, and you are saying that frequentist statistics are always(?) misleading relative to Bayesian methods. I'll have to look at this more carefully (I keep telling myself to learn the Bayesian approach, but I still haven't sat down and done it). I had thought that the main misuse of frequentist statistics was in post-hoc analyses of existing data from uncontrolled experiments. That was the other thing I thought you were getting at: that JOC authors were obtaining data, visualizing them, and then deciding to do frequentist tests (after conscious or sub-conscious pre-selection). That's obviously wrong, to me, and I know it happens in my field (biology). I didn't think planned application of frequentist stats in a controlled experimental design was problematic. Time to learn...
  38. How significance tests are misused in climate science
    Agreed, Andrew -- and hooray for the Peirce sighting. Semioticians rejoice.
  39. Solving Global Warming - Not Easy, But Not Too Hard
    RSVP: What do you suggest people will do in 200 years when all the oil, gas and coal have been used up? Or what part of "nonrenewable energy" do you not understand? Maybe they will all move back into caves and make stone tools. Or is it more likely they will have developed renewable energy sources? Since this change has to be done at some time, why don't we try it now instead of damaging the environment with the last dregs of fossil carbon. The exact time when fossil fuels will run out is hotly debated, but they will eventually run out. Then society will develop sustainable energy.
  40. How significance tests are misused in climate science
    I'm unsure why people are so quick to ascribe global warming to pirates, when clearly the opposite is more like, i.e. that global warming is causing a precipitous decline in the number of pirates. This only makes sense, as the increased heat will tend to make our young people lethargic, and so less likely to get up to go to pirate tryouts, and to attend piracy school. Also, paleoclimate data has shown (with statistical significance) that piracy changes lag temperature changes by several hundred years. At the same time, as someone whose brain hurts whenever I think about probabilities in any sense beyond my chances of finally winning the lottery, I must admit that I find statistics and statisticians as annoying as piracy and pirates... perhaps even more so. If only global warming had such a negative impact on statisticians! Alas, and alack, I fear that the opposite is the case. I'm far more cognizant of statisticians in this woefully warming world. I also have no doubt that statisticians keep Bayesian eye patches in their desk drawers, to be worn in complete secrecy in the privacy of their lairs, while performing their heinous acts of statismancy and probabalism. The line between pirate and statistician is, I fear, as blurry as the line between p(M|N) and p(N|M). Arg.
  41. Keep those PJs on: a La Niña cannot erase decades of warming
    HR, I think your original remarks about the GISS report were way off base, and I don't think your subsequent effort to retroactively salvage them is particularly justifiable. They wrote that at the end of a very hot summer which saw both the record-breaking 12-month high temperature and a series of high-publicity stories about the heat wave in Russia, etc. If GISS operated the way that many "skeptics" imagine, they could have easily issued a summary that did exactly what you initially assumed it did -- ascribe everything to AGW and not even mention the role of natural variability. Instead, they provided a summary in more or less neutral terms that discusses natural variability at very great length. IMHO the fact that their efforts were apparently not enough for you says much more about your biases than theirs. (Though I obviously am coming from a different point of view; it's possible that their summary seems more reasonable to me because I'm predisposed to agree with them.) HumanityRules continues: If the GISS document can say that the 1998 temperature was boosted by El Nino why can't it acknowledge that 2010 was also boosted. Instead it tries to focus on the cooling aspects of the developing La Nina. They point out correctly that 2010 was influenced by a moderate El Nino that then transitioned fairly rapidly to a La Nina. In contrast, 1997-1998 had an El Nino that was either the largest on record, or second largest (after 1983, depending on which index you follow). Look at the data in the NCAR paper you cited. This past year's ONI (index based on the Nino 3.4 region) peaked at 1.8, and was above 1.5 for a grand total of two months. In contrast, for 1997-1998 it peaked at 2.5 (the highest value in the 60-year record), and it was above 1.5 for eight months, not two. If you believe that El Nino has a significant impact on temperatures, then why can't you accept that a monster El Nino (like 1998) would have a much larger impact on temperatures than the comparatively modest El Nino of 2010? So, to me, it frankly looks like you're being rather unreasonable. GISS talked about El Nino appropriately, and appropriately noted that the most likely reason why 2010 may not break the all-time calendar year record is because the El Nino was relatively modest in magnitude and rapidly transitioned to La Nina. Seriously, how much more can you ask? It seems like you wouldn't be satisfied unless GISS came out and ascribed the entirety of 2010's warmth to natural cycles. Or perhaps you want them to pretend that the 2010 El Nino was as large as the 1998 one, even though it obviously wasn't?
  42. How significance tests are misused in climate science
    Actually there might be a tenuous link with pirates and warming. eg. I think it was the Royal Navy that eliminated a lot of piracy. But they had to chop a lot of trees down to do it, plus the age of ironclads and battleships (coal use) meant pirates needed to be more sophisticated with access to a better income stream to afford a steam boat with heavy guns. Also piracy became a state sanctioned aim during the world wars with submarines, but the motive wasn't to steal produce. Although maybe that was the Nazis big mistake. They should of stolen the convoys, rather than sinking them?
  43. How significance tests are misused in climate science
    Really, this is a very formalized demonstration of why syllogistic argumentation is not a conclusive or reliable means of establishing truth-values. I'm reminded that the great US philosopher Charles Sanders Peirce (19th C) whose father Benjamin Peirce was a pioneer in statistical theory (esp. outliers) himself, admonished his readers that any argument depending on syllogism was to be implicitly mistrusted. He claimed the better means of understanding is by examining the substantial implications and possibilities of relations between things exhaustively, instead of attempting to fit them into formal logic. Still good advice over a Century later!
  44. How significance tests are misused in climate science
    I recently saw an article in a journal that supported AGW but the numbers weren't significant at the p<0.05 level. So AGW isn't real because every supporting evidence needs to be above the 95% certainty level. Oh, wait...this isn't WUWT?
  45. How significance tests are misused in climate science
    Hoooray! We're saved. Daniel's chart 'proves' that global warming is caused by lack of pirates... but in the past several years piracy has been booming off the coast of Somalia! We should start seeing temperatures turn around now! :]
  46. How significance tests are misused in climate science
    Re: Alexandre (1) To illustrate your point: Of course, some will argue that the recent surge in piracy is the cause of the "perceived flattening of the global temperature rise". Sigh. In life and statistics, some will see only what they expect to see. The Yooper
  47. How significance tests are misused in climate science
    I was playing around with statistics a few weeks ago. It helps me understand Tamino :-) Then this claim below crossed my mind, just like Dr. Ambaum: In the meantime, we need to live with the fact that “statistically significant” results are not necessarily in any relevant sense significant. I think you could statistically correlate car sales and global warming, for instance, and it would mean nothing. It's the underlying physics AND the statistics that will give you the evidence - which is the case.
  48. Ice-Free Arctic
    Norman, let me ask you something. The stuff you are promoting suggests that the decline of Arctic sea ice has just been a 'natural cycle' which should end 'any time now' (actually about ten years ago). You've convinced yourself that the past nine years are 'flat' (for the record, they look more like 'straight down' to me) and thus that the inevitable ice growth of the natural cycle is right around the corner. If five years from now Arctic ice has grown considerably I'd be absolutely shocked and need to re-examine how the apparently overwhelming indications to the contrary could all have been so wrong. So here's the question... if in five years Arctic sea ice is instead sharply lower even than current levels will that be an indication to you that something is very wrong with what you have chosen to believe? Or will you just accept whatever the new 'skeptic' explanation is (my money is on, 'oh we expected the Arctic to melt out entirely all along... this is completely normal and really happens all the time') and go on disbelieving all evidence to the contrary?
  49. Climate cherry pickers: cooling oceans
    Humanity Rules #13, #16 Excellent comments HR. What the promoters of CO2GHG theory have to consider is that the total sum of the forcings is what counts. If S-B cooling and cloud albedo cooling are offsetting CO2GHG warming and WV feedbacks at such a scale that warming is flattening or being arrested - then the accumulation of energy in the biosphere must also be flattening. Dr Trenberth found a theoretical 'observed' 145E20 Joules/year energy imbalance (0.9 W/sq.m) with a 'residual' of 30-100E20 Joules/year unaccounted. ie Av 65E20 Joules/year out of 145E20 Joules/year is unaccounted. This is 80/145 or 0.5/0.4W/sq.m split. What must be explained is that better measurement by Argo since 2004 shows flattening increase (or no increase) in OHC at a period when CO2GHG warming and WV feedback are at their highest theoretical levels. If better measurement of OHC content converges on less OHC increase then other cooling factors must be at play - cloud albedo and S-B are prime candidates.
  50. Real experts don't know everything
    Norman #64: "Climate models predicted a warming Arctic and the current warming found in the region may seem to verify the model is accurately predicting what is going on (CO2 increase by man is heating the Arctic region and causing increased summer ice melting). However this arcticle points out that another forcing factor is better at explaining what is going on in the Arctic then the AGW theory." Chylek's claim of correlation between the AMO and Arctic sea ice decline, followed by the assumption that this supposed correlation equals causation, is (like AGW theory) a theoretically possible explanation. However, the claim that the issue ends there with two possible explanations is pure nonsense. We can gather data and test these ideas to see whether they hold up or not. If the AMO were responsible for Arctic sea ice decline then we should have seen a reversal to increasing Arctic sea ice some time around 2000. The AMO period isn't absolutely fixed so it could run over a few years, but we're now at ten and the decline of Arctic sea ice is still accelerating. In short, data contradicting this idea is accumulating. Every year the ice continues to decline is another year against it. Also, if this were just a case of oscillation within normal climate bounds the long term average should be flat... but it isn't. Ice volume now is lower than it was during the last AMO cycle. That indicates that we aren't just dealing with an oscillation that moves heat back and forth, but rather an increase in the total heat input. On the other hand when we go to check AGW theory against data we find that ocean temperatures world-wide are increasing, that some of this warmer water is flowing into the Arctic from the Pacific and contributing to melt, that LAND ice is also melting (AMO obviously isn't causing that), that we see changes in upwards and downwards radiation matching what AGW should cause, that the warming is seasonal (more pronounced in Winter) as it should be under AGW (and would not be if AMO were responsible), and a thousand other things which match up. So no... it isn't just two different ideas about what could be happening. It is one idea which fits the observed facts and one which does not.

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