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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 104651 to 104700:

  1. The science isn't settled
    Eric #29: I reject the idea that good scientists would not look for counter-evidence that is not biased or tainted by their current theories Einstein: Quantum mechanics is certainly imposing. But an inner voice tells me that it is not yet the real thing. The theory says a lot, but does not really bring us any closer to the secret of the "old one." I, at any rate, am convinced that He does not throw dice. Me: So Einstein questioned Quantum Mechanics by appealing to philosophy, an "inner voice" or religon, but not to any counter-evidence. Given that scientists are human beings, have belief systems and make their names by publishing it seems unlikely that any of them, which ever side of the debate they are on, would be completely unbiased, if only subconciously. What we should insist on is that the science as a whole be unbiased, not the individuals practising it.
  2. The science isn't settled
    Tom, I had to break my rule after adding "empirical" to your google search for "string theory". In the first link returned http://www.chowk.com/articles/8213 the author might suggest that I am a logical positivist, stuck in the early 1900's. The author says "Einstein, Dirac and many other scientists had intuitive kind of faith in the correctness of their theories without empirical evidence." He goes on to say they used subjective criteria to underlie that faith. I have that same faith in my theories of the world except I am not capable of venturing into relativity except where it is actually empirical. Given new evidence or new theories that conflict with mine, I will change to the combination of old and new theories that are completely consistent with the evidence. As for (objectively) statistical evidence, I am probably guilty of what Hoekstra http://pbr.psychonomic-journals.org/content/13/6/1033.full.pdf calls "probability as certainty" or "binary thinking". I take the view that most of those cases are avoidable, that direct evidence is available. While you again appeal to the concept of "theory-laden" observations, I reject the idea that good scientists would not look for counter-evidence that is not biased or tainted by their current theories. I think we will have to agree to disagree on that.
  3. Climate change from 40 million years ago shows climate sensitivity to CO2
    #69 RVSP Using this calcualtor tool: Calculates temp in absence of GHG. Is it possible Mars could have had water with a faint Sun? In the past, if the Sun was 70% as bright as today, Earth would receive 958 watts/m^2. Mars receives 2.5 less radiation than Earth so it would have only received 383 watts/m^2. The lowest the calcualtor goes is 800 watts/m^2 you have to interpolate the rest. Find a higher number on the solar scale and drop it by 417 watts/m^2. Watch how that lowers temp. Then look at the Earth's temp at 800 watts/m^2. Take that temp number and subract from it what you get with the difference of 417 to see what the temp would be at 383 watts/m^2. I was getting -100 F for a global temp (-59 F + -41 F). If you add a nice Greenhouse effect of 70F you are still -30 F. It would be like having a flowing river in Antartica in the Winter.
  4. Climate is chaotic and cannot be predicted
    #16 scaddenp ""Chaos" has a formal definition, and this doesnt meet it. Non-linear and sometimes highly sensitive to changes in forcing, but its not showing signs of developing in highly different directions for slight changes in conditions. You dont get an iceage because there is a volcano erupting." I guess that would depend on what you define as "slight". I am not the Master of Choao theory on the detailed definition. Here is a model of Earth's temp (simple model). It calculates Earth temp based on only solar energy and Albedo. This would be Earth without any GHG warming. But it is useful in demonstrating that Climate is indeed chaotic. Primarily with the Albedo (the Solar energy will not change much). They have lists of Albedo's to put into the calculator. I noticed that if the Earth were mostly forest the albedo would be much lower (oceans would be the same at there low albedo). Put in a lower albedo and see what happens to the Earth's temp even with no GHG effect. And you claim this is not a chaotic system? If the land is grass, desert, snow or forest it makes a huge difference in albedo and the overall temp. Try it and see and if I am wrong explain what is the flaw in my thinking. Thanks. Albedo Earth Temp calculator.
  5. Solving Global Warming - Not Easy, But Not Too Hard
    Re: RSVP. Another point RSVP is that the discussion was about the 'Free Market' which is a specific political view of economics.
  6. Solving Global Warming - Not Easy, But Not Too Hard
    RVSP: "Economics is the most honest measure of human motivation, which is in turn tied directly to natural chemical energy. If you havent seen this happening, you can be sure it is due to some unnatural political ideology." The fact that you stick to this inaccurate view actually implies that you have an ideology yourself. There is no intrinsic connection between economics and chemical energy. Like a religion, economics only exists in the human mind, chemical energy exists whether humans exist or not. In future stick to reality and not your beliefs.
  7. Solving Global Warming - Not Easy, But Not Too Hard
    RSVP, and you've somehow missed the fact that free market capitalism is itself an 'unnatural political ideology'?
  8. Climate is chaotic and cannot be predicted
    I dont have access to my paper lists (nor to my knowledgeable colleague) at home but if you look at Chp6 IPCC WG1 and look at section on "Abrupt climate changes in the glacial-interglacial record". Note that these are not necessarily global events - indeed some types are hemispherically anti- phased. Look at cites for main review papers. Note that this is very active field with interesting papers in the pipeline.
  9. Skeptical Science moving into solutions
    Berényi Péter @24 No BP, It's not a political agenda. Politics is the great irrelevency in the world. It is about recognising that human affairs and how we choose to run this planet have to fit within the constraints imposed by Mother Nature (to anthropomorphise a bit). And that the biggest problem in our attempt to do this is us. Human psychology thinks that we are the centre of existance and the world has to fit around us. This is what most people think of as the 'real world'. In reality the 'real world' is physics, physics, physics & physics. We are just an add-on. The disjunction between reality, and what people 'think' reality is, is at the very heart of the problem. And Old Ma Nature is a very unforgiving sort. 'You didn't realise I was serious dearie? Sorry, Your extinct?'. Her rules, her bat and ball. So to say we need to find strategies to connect people with reality (I won't say reconnect because we may never have been in the past) is not a political agenda. It is simply stating that we need to show people what a grown-up perspective on reality looks like. And politics isn't grown-up. Its just the sand-pit in the kindergarten.
  10. Solving Global Warming - Not Easy, But Not Too Hard
    archiesteel #136 "Discussions about the Free Market do not belong on this site, as they are political, not scientific, in nature" Tell that to a professor of economics. Economics is the most honest measure of human motivation, which is in turn tied directly to natural chemical energy. If you havent seen this happening, you can be sure it is due to some unnatural political ideology.
  11. Skeptical Science housekeeping: Comments Gluttony
    John, I agree with your comments policy. I recently spent some time posting comments on Newsbusters.org to preach to conservatives on man-made global warming, and I got ALOT of accusations of deception, disheartening insults, and character assination. I've already given up preaching to conservatives, I like it much better here were I can participate in intellegent discussions on climate change. Your comments policy really makes this website special.
  12. The science isn't settled
    But Eric, why do all scientists in all disciplines use the phrase "competing theories," since by your definitions such things cannot exist? According to you, in each domain there can be only "the" theory in which 100% of scientists have 100% certainty, plus competing "notions." So you call string theorists mere "string notionists"? But if 100% of scientists are 100% certain about the non-string physics theories, then those string notionists are not really scientists at all! They are poseurs! Another implication of your claims is that inferential statistics must never be used to analyze data, if those data are going to be used to verify a theory, since you claim that evidence less than 100% certain cannot be used to support a scientific theory, and inferential statistics yields probabilities between 0 and 1, exclusive. You also drastically restrict the ways in which a theory is replaced. If 100% of scientists are 100% certain in the correctness of "the" theory, then none of them would waste their time even entertaining alternate notions, let alone actively constructing alternate notions nor collecting data to support alternate notions. Nor would they waste their time gathering more evidence in attempts to further support the existing theory. The discovery of data that the current theory cannot handle must happen only accidentally, then. Clearly that is not how science really works. And then there is the problem of incomplete theories. Classical, Newtonian, theories of physics cannot explain the things that relativity theory and quantum theory can explain, and the latter two cannot explain everything, either. So by your definitions, none of those is a theory; all are mere notions. Which means there are no theories of physics right now!
  13. Climate is chaotic and cannot be predicted
    "Chaos" has a formal definition, and this doesnt meet it. Non-linear and sometimes highly sensitive to changes in forcing, but its not showing signs of developing in highly different directions for slight changes in conditions. You dont get an iceage because there is a volcano erupting. It is well worth reading Broecker - another one in works - but his work on the sudden hemispheric climate reversal's doesnt give you any reason for thinking the current warming is related to causes of these events. And no reason for thinking these events dont have specific causes. Catch up on some recent literature.
  14. What should we do about climate change?
    BP has posted some links describing the status of thorium reactors. Apparently these have not been built yet and are completely theoretical. Since a pilot plant will have to be built before any full scale reactors it will be at least 15-20 years before full scale reactors come on stream. I think that is too long to wait for a solution to be started and that other technologies are pursued while nuclear works out its problems.
  15. Solving Global Warming - Not Easy, But Not Too Hard
    BP, I read some of your Nanotechnology Roadmap and I see no mention of fixing gigatons of carbon. They rely on fossil fuel for their carbon. Your claim that this would remove the carbon from the atmosphere is false. Cite a page number that supports your wild claims. Then cite a peer reviewed paper, not an industry piece. Why do you ruin your reputation at this site with such absurd claims??? I see from your links that thorium reactors have not yet been built and are a completely theoretical proposal. I hope they work when they are finally built, at least ten years from now. The amount and type of radioactive waste from those reactors is unknown at this time. We need solutions now, not in 200 years. A two hundred year timescale is useless for my children, their children and me. I am astonished that you now claim your proposed solution is not useful for two hundred years.
  16. How significance tests are misused in climate science
    Tom Dayton, Eric L, Tony L and sout, Thank you for your comments and links. I understand this issue better than I did before.
  17. The science isn't settled
    Tom, thank you for that latest link which I have saved and will reread on occasion. Unfortunately I can't respond on this topic anymore.
  18. The science isn't settled
    Eric, it's frustrating that you merely repeat your assertion without responding to the evidence I have provided in links. Here is another link, this one about underdetermination of scientific theory, from the Stanford Encyclopedia of Philosophy.
  19. The science isn't settled
    Tom, most of your links suggest that science has been separated from, or progressed beyond what they call "Baconian inductivism". This appears to be a modern consequence of the need for theories of phenomena that are not directly observable. Your latest link gives examples of "atomic theory and the theory of gravity". The observations are thought to be "theory-laden" therefore unsuitable for inductive reasoning. The paper proposes using the principles of parsimony and "how well a theory ties in with other theories". But those are simply principles of concept formation. There is no difference between concept formation in all nonscientific realms and theory formation in science. The attempt to posit a difference leads to absurdities like the example in your paper: rejecting the theory that the moon is made of green cheese because of the "law" (no longer just a principle) of parsimony. In fact the moon is not made of green cheese because of a large number of theories and observations that conflict with that theory. No (falsely elevated) "law" of parsimony is necessary to reach that conclusion. Ultimately the real reason for such acceptance of subjectivism in science is revealed in your link: "Scientists (and regular human beings) are also affected by cultural, social, and personal beliefs.... Rather than the traditional view that science is to be protected from biases and other imperfections of people, it turns out that science is inescapably infected with humanness." That notion might be a good way to study past errors in science or science history, but it has not scientific purpose, is not required and must be rejected. This paper http://www.johnmccaskey.com/Induction%20and%20Concepts%20in%20Bacon%20and%20Whewell.pdf has a concise explanation of induction as used in modern science.
  20. The science isn't settled
    Tom, theories have one state, certain, otherwise they are not theories but notions.
  21. Solving Global Warming - Not Easy, But Not Too Hard
    @TOP: I'm not a botanist, or anything, but I'm pretty sure you can't plant a lot of trees per square meter in sand and rock.
  22. Solving Global Warming - Not Easy, But Not Too Hard
    @BP " Just a free market with no subsidies whatsoever and proper regulations (to ensure for example no high tech poison is left behind)." Discussions about the Free Market do not belong on this site, as they are political, not scientific, in nature. If we look at it from a scientific point of view, there is in fact no indication that Free Markets are self-correcting. The few historical examples we have of "true" free markets show they are unstable. Let me put it another way: there is a lot more empirical evidence supporting AGW theory than there is for the Invisible Hand of the market... Let's assume some degree of interventionism in the economy, because there will be - that's a pretty safe bet, whatever your own political ideology (death and taxes, and all that)...argue for Laissez-faire all you want, you can't scientifically prove its benefits, so don't bring it up in a scientific argument.
  23. Solving Global Warming - Not Easy, But Not Too Hard
    @clonmac The stuff coming out of Wiezman solves the problem. There is a finite amount of petroleum/coal. Planting the Sahara in trees would put a forest there that would pretty much outlive the lifetime of known coal and petroleum reserves and would remove all the current so called anthropogenic carbon from the atmosphere. It's not a wedge, it's the whole Gouda. I don't like the term sequestration for this because that term implies an activity that is solely for the purpose of removing carbon. Remember one of the forcings is reduction of forests and this is just changing the sign of the forcing with inherent benefits.
  24. Solving Global Warming - Not Easy, But Not Too Hard
    The "short-termers" here (i.e. those who say renewables are too expensive) are the same types of people who got us into this mess in the first place. You can't fix long-term problems with short-term solutions.
  25. Solving Global Warming - Not Easy, But Not Too Hard
    @62 BP: your post is highly misleading, bedcause it implies a beautiful grassland was spoiled by the buidling of the solar plant. However, Carrizo Plain is a huge area, and there is no evidence that significant loss of habitat occured. This is the same saying a photo of a polar bear swimming in water is evidence that global warming is true. It is illogical, irrational, and beneath you. You should retract yourself immediately.
  26. The science isn't settled
    No, Eric, you are very wrong that theories have only the two states of certain and uncertain. If somehow you did not get that point out of the links I provided earlier, try this page for an overview, and if you object to any of its claims, please do read the sources cited there for those claims: The Nature and Philosophy of Science. There is nothing special about that particular web page; you can find the same information easily in textbooks and in multiple places on the internet.
  27. Solving Global Warming - Not Easy, But Not Too Hard
    @45 RSVP: "Where all the natural gas is??" Solar and wind plants on the surface do not preclude natural gas mining below. In any case, not all of these desert environments have natural gas in substantial quantities.
  28. The science isn't settled
    Tom, thanks for the links. The proper role of probability and statistics in science is the evaluation of multiple samples of imprecise data (e.g. regression analysis of imprecise measurements, multiple model runs, sensitivity analysis, etc). That is basically what you would probably call "objective probability". See an explanation of that here: http://plato.stanford.edu/entries/science-theory-observation/ The "defense of IPCC's Bayesian methodology" claims that "Climatological analysis of the AR4 requires subjective assessment." I disagree. There is no requirement for subjective assessment in science. Science builds from a conceptual framework of theories based on observations. If the theories fit observations and each other, then they are certain. If the theories don't fit the observations or the theories conflict, then new theories are required. Those are the two states of science, there are no states in between.
  29. Miriam O'Brien (Sou) at 07:04 AM on 14 November 2010
    How significance tests are misused in climate science
    Thank you for this. I see problems more often (or more obviously) in popular articles about health-related research than climate-related research. Sometimes it's journos drawing invalid conclusions, on occasion it's been researchers apparently deliberately misrepresenting their own research (eg obesity). I'm not sure if some disciplines get better training in stats, or have access to professional statisticians. Tamino has posted a comment on this article that might be of interest to people: Tamino on Ambaum and stats
  30. How significance tests are misused in climate science
    I have not read Dr Ambaum's paper because it is not yet available in my bibliographic source but I look forward to it. I think that Eric L's comments are particularly insightful and it would be good if the Dr. would respond to them. More generally, I do experimental research in the social sciences and have always been aware, since my very statistics course of the difference between statistical significance and quantitative differences in effects. I cannot believe that climate scientists are not aware of this or do not understand the distinction. If you have taken advanced stat courses, you understood it or you failed the courses. In my studies, which are generally on very large samples of families (several thousand experimental and control members) it is relatively easy to show statistical significance when the quantitative differences in treatment effects are relatively small. And the first question that arises, especially from practitioners, is if this is real how much or how many cases should we expected to occur in which these changes will be observed? Statistical significance does indicate that an observed difference is real. There are other way of answering the question, is the size of the effect minor, moderate or large?
  31. The 2nd law of thermodynamics and the greenhouse effect
    Michele, back-radiation from cooler air to warmer earth is perfectly valid. Radiation from a cool object can be absorbed by a warmer one. Example, take a glow-in-the-dark haloween mask, put it in the fridge for a few minutes, then take it out. Can you see it glowing? If so, that means that your warm eyes are absorbing radiation emitted by a cooler object, which is exactly what back-radiation is about. So the idea of back-radiation does not contradict the second law of thermodynamics.
  32. Berényi Péter at 03:40 AM on 14 November 2010
    Solving Global Warming - Not Easy, But Not Too Hard
    #129 michael sweet at 10:38 AM on 13 November, 2010 Please also provide a link to a functional, full scale thorium reactor. We are talking about a two hundred year timescale, don't we? However, there is some aging background material, possibly more than one would wish for. International Atomic Energy Agency, November 2002 IAEA-TECDOC-1319 Thorium fuel utilization: Options and trends Proceedings of three IAEA meetings held in Vienna in 1997, 1998 and 1999 There are also private companies like DBI or Lightbridge going for a full thorium cycle. DBI is planning to build a small, modular, gas-cooled, carbon moderated thorium reactor demonstration plant in Chile. There may still be legal obstacles. The Thorium Energy Security Act of 2010 was introduced in the Senate of the United States on March 3, 2010, was read twice and referred to the Committee on Energy and Natural Resources.
  33. Keep those PJs on: a La Niña cannot erase decades of warming
    #65: "because nearly all of the warming in the last 30 years happened in a step in the end of 90's." OK, so here is a graph of HADCRuT global from the last 30 years. That positive trend of ~0.16C per decade must be what you mean when you say 'a step'. "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" So we'll go back to the beginning of the 70s: Pinatubo's 'offset' are those low spikes in the early 90s. Short duration. Transients. Here today, gone tomorrow (as opposed to that same positive trend). How Pinatubo 'offset' the warming supposedly 'caused' by a decades-long oscillation is beyond me. A google search of 'correlation pdo amo detrend warming' immediately shows watt the source of this illogic is. But then its easier to repeat than to think; do I hear a chorus of 'four legs good, two legs bad' coming from that direction?
  34. Climate cherry pickers: cooling oceans
    HumanityRules there's one point i think is missing/misinterpreted about Trenberth's remarks. Trenberth is talking about variability and I assume we all agree that we do not yet have the capability to follow the enregy flow over the short time period. Don't forget that we're talking about a time span of a few years, which does not have any particular meaning as far as the big picture is concerned. This is why we should like to have a better measurement system, not because it could in any way change/confirm what we already know but because we may learn a lot about some details of our climate system.
  35. Climate cherry pickers: cooling oceans
    Re: Berényi Péter (19) Nice comment. I must point out, however, that in the previous instances where a major disconnect was found between the models and measured data (such as with satellite data and Argo ocean data), there were found to be errors in the data collection. Once corrected, the data were then found to match the models. For serious flaws to exist in the models, which are based on the physics of our world, it is very likely that this would have been noted before now. Unless you have evidence to the contrary and a physics-based theory that explains why the models match reality the vast majority of the time for everything but OHC data? The jury is still out on how reflective of OHC the depth (sorry, no pun intended) and breadth of the Argo/XBT data is. While a great resource, it must be considered part of an incomplete picture of OHC and incapable of closing the global energy budget gap. The Yooper
  36. Berényi Péter at 23:54 PM on 13 November 2010
    The science isn't settled
    #18 Tom Dayton at 14:38 PM on 13 November, 2010 "Galileo was 100% certain that there are mountains on the moon." I am sure he was. He actually says it in his booklet Sidereus Nuncius: "I have been led to that opinion which I have expressed, namely, that I feel sure that the surface of the Moon is not perfectly smooth, free from inequalities and exactly spherical, as a large school of philosophers considers with regard to the Moon and the other heavenly bodies, but that, on the contrary, it is full of inequalities, uneven, full of hollows and protuberances, just like the surface of the Earth itself, which is varied everywhere by lofty mountains and deep valleys." However, you miss the point. Galileo's state of mind may be interesting from a historic point of view, but it is absolutely irrelevant to science. What matters is the evidence he gives in subsequent sections starting with "The appearances from which we may gather these conclusions are of the following nature: [etc. etc.]" (and also the detailed description of the instrument used for observation, given in previous sections). That's what makes his observations repeatable and his conclusions verifiable. This is what constitutes the scientific method and makes him a scientist. Without it he would be just another Moongazer disseminating vague Witchy Wisdom of Gaia’s Sacred Circle.
  37. 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.
  38. 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.
  39. Solving Global Warming - Not Easy, But Not Too Hard
    BP: "Your arguments are getting wilder and wilder." Indeed.
  40. 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!
  41. 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.
  42. 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.
  43. 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.
  44. 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.
  45. 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.
  46. 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."
  47. 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?
  48. 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.
  49. 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
  50. 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.

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