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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 113751 to 113800:

  1. Rob Honeycutt at 04:55 AM on 3 August 2010
    Visually depicting the disconnect between climate scientists, media and the public
    Excellent point canbanjo... If 800 is the numerator (that even being a stretch), what is the denominator? 10,000? 20,000? More? If you ran those numbers I think you'd be pretty close to the 97% and 3% figures again.
  2. Ian Forrester at 04:54 AM on 3 August 2010
    Has Global Warming Stopped?
    Poptech said:
    Sorry boys 95% is what statistically significant means. Anything less would not be "statistically significant".
    So, in your distorted view of reality "warming, but not at 95% significance" means "it's cooling"? No wonder your list of papers is so flawed.
  3. Has Global Warming Stopped?
    Thank you for the clear and concise discussion of the statistics behind the controversy. The real problem here is illiteracy with regards to the language of statistics among lay people. That's not hard to understand, I'm very nearly statistically illiterate. If anyone should be brought to task over this brouhaha it is the media outlets asking the question and reporting on the answer. Maybe I'm old fashioned, but if you ask a question and you're pretty darn sure the vast majority of your audience is not going to understand the answer, I think there is an obligation to ask Prof. Jones for a more in depth clarification of what the answer means. To take the answer that most of your audience doesn't understand and turn it into a sensationalist headline that doesn't reflect reality is just abysmal journalism. Unfortunately abysmal journalism seems to be contagious and running rampant through our society these days.
  4. actually thoughtful at 04:45 AM on 3 August 2010
    Has Global Warming Stopped?
    Of course it stopped! It has been cloudy and cool at my house all week!
  5. Waste heat vs greenhouse warming
    RSVP, ignoring the nonsense part: Outside of this particular point, the main question is whether global warming is due to GHG vs waste heat. For now it seems according to all the data that GHG overwhelm waste heat on a global average. This may be the case. 169 posts later. Some of us enjoy the journey, others the destination. Maybe even both.
  6. Visually depicting the disconnect between climate scientists, media and the public
    Poptech, If you believe in quality, you must be able to identify the most important papers from your list. If it is only a numbers game as you seem to be saying, then pro AGW papers will win hands down. Thanks
  7. On Consensus
    DM at #23 I don't think good and persuasive writing and argument are separate from facts or scientific reasoning. They are an integral and possibly neglected part of it. If a judge, your daughter, your Ph.D review committee or the public has been confused by someone's mis-stating or obfuscation of the facts, simply stating the facts again won't be persuasive in any of those forums. True, any political effort must follow the science rather than the other way around. But simply trying to ignore that you have to write and argue persuasively will just get the pro-science side in more trouble. And, I assume they know your tactics - some of the denier memes may be counting on the fact that you will retreat into "objective" statements of the science in hopes that the public won't be able to tell the difference between their gobbledegook and your science.
  8. Rob Honeycutt at 04:34 AM on 3 August 2010
    Visually depicting the disconnect between climate scientists, media and the public
    Poptech... You've actually ventured into my area of professional expertise here with quality. Quality is NOT subjective. Aesthetics may be subjective, within a range of perception, but even then experts - even in an area as subjective as 20th century abstract art - can readily agree on what constitutes quality. Quality is without doubt quantifiable and measurable. It is measured in a wide ranging number of fields and applications. Quality is NOT a matter of opinion. That is a statement which is beyond absurd.
  9. actually thoughtful at 04:30 AM on 3 August 2010
    On Consensus
    Doug @10 Thanks for the visual depiction. While that information wards off the sense that the battle is lost, it doesn't actually show improved understanding of climate scientists. Over the duration of the graph, the pro-science group (3 left most spheres) lost 4%, while the anti-science group gained 4%). This was during an El Nino event, so the outcomes of the current and future warmings were on display. 70/30 feels comfortable. 66/34 feels much less so (even though it is "only" a 4% swing.
  10. Has Global Warming Stopped?
    Well, let's be very careful about what "statistically significant" means. As I tell my students, one should always state the alpha value when making a claim about statistical significance. Thus, this data is not statistically significant at alpha = 5% (95% level of significance/confidence) but it is at alpha = 10% (90% level of significance/confidence). It may be customary to always set significance at the 95% level, but for absolute precision you should state what it is.
  11. 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.
  12. Dikran Marsupial at 03:46 AM on 3 August 2010
    Has Global Warming Stopped?
    robhon@7 The problem with that answer, is that it fails to give a direct answer to the question posed, which is "it is not statistically significant". Failure to answer the question would inevitably lead to an (valid) accusation of being evasive. A scientist should never shrink away from clearly stating the facts, especially when they don't (apear) to support their position. IMHO Prof. Jones provides an excellent example of how a scientist should answer questions, namely directly and honestly. The less scrupulous will twist his words to suit their own purposes, and there is little that can be done to prevent that, but that is an indication of the weakness of their position, not his.
  13. Waste heat vs greenhouse warming
    CBDunkerson #166 You quote me, "Two hot skewers at the same temperatuere when held next to each other will not warm each other." After reading what you wrote, the above is almost the only thing you wrote that is true. The rest goes into refuting things I havent even said (which you call nonsense), but then when you actually do get back to rewording what I did say, "...since neither gets hotter", you are basically agreeing with me. doug_bostrom #167 Let me answer your question with a made up example. Suppose the temperature on the ground nicely heated by the sun is around 30 C. The air temperature say would be 25 C in the absence of anthropogenic GHG. With 100 ppm more GHG, the temperature instead of 25 is 25.5 C. The point here is you will only get the half degree from GHG if local waste heat isnt also taking the temperature up to 26 C as it is in this made up example. Because you are in the city, waste heat is adding 1 full degree Centigrade. Under these conditions the effect of GHG has been clipped by the waste heat. You dont get 26.5 C (1 from waste heat and .5 from CO2). You only get 26 C. I believe this based on what AGW theory itself says.. that GHGs will take temperatures to a new equilibrium. If an external source is adding heat beyond that equilibrium point, GHG will not be allowed to do this (i.e., "impede the effect of GHGs"). Thus answering your question. The other reason I was saying this is based on what I say in #161 with respect to the Second Law of Thermodynamics. Outside of this particular point, the main question is whether global warming is due to GHG vs waste heat. For now it seems according to all the data that GHG overwhelm waste heat on a global average. This may be the case.
  14. Visually depicting the disconnect between climate scientists, media and the public
    Poptech wrote : "My purpose is not to determine which are the top 10 but to provide a resource for peer-reviewed papers that support skepticism of AGW or the negative environmental or economic effects of AGW and to prove that these papers exist contrary to widely held beliefs" No, that is not right. Your purpose was to gather papers from any source (especially from E&E) which YOU believe (despite protests from some of the original authors) "support skepticism of AGW or the negative environmental or economic effects of AGW [ALARM]" - the final word being included in the title to your little list but not, strangely, in the main body describing it (from which your quote comes).
  15. Has Global Warming Stopped?
    ABG, In the video (very good one, btw) you mention that the statistic significance is dependent of how many data points there are (among other things). Does the level of confidence change if we use, say, a monthly series instead of plotting just one figure per year?
  16. Rob Honeycutt at 03:09 AM on 3 August 2010
    Has Global Warming Stopped?
    Ian... I always felt that he could have answered that question far better and been absolutely accurate. BBC: Do you agree that from 1995 to the present there has been no statistically significant warming? Fake Phil (me): I calculated the trend from 1995 to 2009 and the warming trend is positive at 0.12C/decade. That time period is too short for where we'd expect to find a statistically significant trend, but even as such it falls at about the 92% confidence level.
    Response: I sometimes reflect on conversations and think, "man, I should've said that". I have to feel for Phil Jones - he gave a bad interview and now has people all over the world saying what he should've said, including myself. Tough crowd.
  17. Ian Forrester at 03:01 AM on 3 August 2010
    Has Global Warming Stopped?
    Matt, his answer was perfectly correct and his answer was the only honest and correct answer to a loaded question. The question asked was:
    Do you agree that from 1995 to the present there has been no statistically-significant global warming?
    Phil Jones' complete answer was:
    Yes, but only just. I also calculated the trend for the period 1995 to 2009. This trend (0.12C per decade) is positive, but not significant at the 95% significance level. The positive trend is quite close to the significance level. Achieving statistical significance in scientific terms is much more likely for longer periods, and much less likely for shorter periods.
    The dishonest press and deniers, of course, only quoted the first word of his answer.
  18. Rob Honeycutt at 02:48 AM on 3 August 2010
    Visually depicting the disconnect between climate scientists, media and the public
    Poptech... No, quality is not so subjective as you would wish it to be. This is not a case of beauty being in they eye of the beholder.
  19. Rob Honeycutt at 02:44 AM on 3 August 2010
    Visually depicting the disconnect between climate scientists, media and the public
    I was reading an interesting article the other day about how a "scientist" has just written a paper explaining how light from distant galaxies could reach earth when the earth is only 6000 years old. The "starlight problem" as the creationist community calls it. You can imagine my surprise to find out that the paper is out for peer review. Where? The "Answers Institute." Answers in Genesis. By Poptech's standards, this would constitute a legitimate peer review of legitimate science.
  20. Waste heat vs greenhouse warming
    Likewise, waste heat in the atmosphere will impede the effect of GHGs. Following from what?
  21. Visually depicting the disconnect between climate scientists, media and the public
    Hi Poptech, If you wanted to educate an uniformed lay person (or scientist for that matter), which are the most important papers from your list which justify/ demonstrate your understanding of AGW? Perhaps a top 10 for starters?
  22. Has Global Warming Stopped?
    MattJ, Phil Jones was thinking like a scientist and talking like one. Some in the public arena demand he do so, others demand he tailor his words for rhetorical effect. Someone will be damning him regardless of what he says. Anyway, the meaning of his words was crystal clear to anybody not wearing a contrarian cap. There's a recent interview in New Scientist with Jones. His own stated preference is to resume doing research without being hassled by amateur and professional politicians.
  23. Has Global Warming Stopped?
    What was Phil Jones thinking? His answer to the BBC was a disastrous failure to adapt his wording to his audience. No wonder the Daily Mail made it a headline interpreting it as "there has been no global warming" Why, even given that Jones was speaking scientific language rather than popularly comprehensible language, his wording is a disastrous mess. What was "no significance at the 95% significance level" supposed to mean? Worse yet, what possible grounds could he have for insisting on 95% instead of the 92.4% we actually got? None! The article is quite right to point out that 92.4% is good enough to show that yes, we do have global warming over the last 15 years.
  24. What's in a trend?
    Hang on, I misread that. 1940 + 60 = 2000. This! is the first complete decade of a cooling period? Personally I'd be really pleased if this was right. But I do hope the last few summers here are not representative of a "cooling period".
  25. Visually depicting the disconnect between climate scientists, media and the public
    So, 16% of Poptech's little list can be discounted straightaway, because the relevant papers come from E&E. That's good to know. I have also read lots of other criticisms of that list on so many different blogs, etc. that I reckon less than half are actually valid in any pertinent way. That just leaves the papers that Poptech subjectively reckons are anti-AGW (despite what their own authors say - even after being told by Poptech what their papers actually say !), so not very many.
  26. On Consensus
    This comment should be tidied and then upgraded to a blog post; it's a marvelously clear explanation, the double-pendulum employment and graphic beautifully illustrates the difference between weather and climate.
  27. 1934 - hottest year on record
    I believe you may have missed a point too... the NCDC-NOAA has systematically lowered the early Weather Bureau records. Heavily freighted words. I suppose you'd like us to form some conclusion? Why not say it, or is it more theatrical to leave a decaying, unresolved chord in the dramatic score? These were not single-day records, but monthly records... So what? Put a network of thermometers together, produce a monthly high and low averaged between stations and the same effect I mentioned will apply except more so: most unprecedented and subsequently unparalleled extremes will be found in the earlier history of the network. If there's an overall shift in surface temperature it'll take a while to show up in monthly state-wide records. There's nothing complicated about this. I don't think you understand Meehle's paper, perhaps because you're looking at things through a conspiracy filter. Certainly your failure to understand the expected longitudinal distribution of extremes from a thermometer network suggests you're not very clear on the topic Meehle discusses. Try to be more objective, take the opportunity to learn from Meehle's expertise.
  28. What's in a trend?
    #21 "every indication that the cool period is now upon us." What would those indications be?
  29. Rob Honeycutt at 01:51 AM on 3 August 2010
    Visually depicting the disconnect between climate scientists, media and the public
    Poptech... What constitutes a specialist is not subjective at all. I can't randomly perceive someone to be an expert and expect that to be correct. What constitutes as a expert has much more to do with quality and quantity. And for the use of E&E for the majority of your "800 papers." That's tantamount to bottom feeding. It's where scientists go when they can't get published in respected journals. You know this is the case. Even the fact that you absolutely insist that your statements are "100% correct" shows the absurd level you are willing to go to. You exhibit a bizarre megalomaniacal adherence to your own capacity to understand an issue that not even the most eminent scientists in this field would lay claim.
  30. Dikran Marsupial at 01:21 AM on 3 August 2010
    On Consensus
    dcwarrior It is true that rhetoric often has a greater effect on public opinion than science, however it is vital to clearly distinguish between scientific arguments and rhetoric in our responses. If someone makes a specious scientific argument, then it is best answered by a straight scientific response, and that is what SkepticalSciece does so well. What we shouldn't do is respond to specious scientific arguments by engaging in rhetoric ourseves. If we do that we run the risk of being seen as dishonest and lose the trust of the public (and indeed we would deserve to lose it) when our rhetoric is exposed for what it is. Of couse scientists need to understand rhetoric, but (IMHO) only to better advise journalists and politicians to argue for the scientifically justified political and economic action and to expose the flaws in the arguments of the opposition.
  31. Has Global Warming Stopped?
    That video might get a couple of airings with some statistics students. Good stuff.
  32. 1934 - hottest year on record
    Broadlands, your sources are from 1941 and 1943 - a bit out of date now, don't you think ? If you look at NewYorkJ's comment, you will find more up-to-date and accurate information. From one of the links there, you will find that 1998 was the 'hottest year' in the US, closely followed by 2006, then 1934, 1921, 1999. If you don't trust those figures, that is up to you to explain. Perhaps you should show in what way you believe they have been fiddled somehow. Also, you shouldn't concentrate on daily or monthly maximum temperatures, which are more likely to be the result of local weather - best to concentrate on trends, like this study : The relative increase of record high maximum temperatures compared to record low minimum temperatures in the U.S
  33. Has Global Warming Stopped?
    Based on this very nice bit of work, I s'pose we can predict that warming will keep on stopping - apart from the occasional wild El Nino year. Much appreciated.
  34. On Consensus
    "Science is not about rhetoric, it is about logical argument." Regarding the conduct of science, you are spot on. However, given the population we have now, rhetoric is still necessary to convince the population that they should be concerned about climate change. Blaming science education, while true in a reductionist sense, will not get the results you want. If science wants to win this battle, it needs to understand the tools the opposition is using, VERY EFFECTIVELY, against you. WHY are people being persuaded by a, by all accounts, small group of deniers? They appear to be very politically astute and seem to be pushing people's buttons in a way that they respond. I'm no marketing maven but I know there is science out there on how to persuade people of things - will hard science understand that they need to power of soft science?
  35. Anne-Marie Blackburn at 00:21 AM on 3 August 2010
    Has Global Warming Stopped?
    Good post and what looks like an excellent new resource to fight denialism. Thank you.
  36. Dikran Marsupial at 23:25 PM on 2 August 2010
    On Consensus
    nnthinker said "Not a very good defense". Science is not about rhetoric, it is about logical argument. Casual dismissal of posts intended to be helpful is not an indication of genuine scientific scepticism. Physics can't predict the exact behaviour of a double pendulum because it is chaotic; being able to measure the initial conditions more accurately extends the useful prediction horizon a little, but it doesn't change the fact that a double pendulum is inherently unpredictable. Likewise the weather is inherently unpredictable, and more accurate measurements don't substantially change that, just pushes the useful prediction horizon back a little (for a more advanced treatment, see here). Model predictions are not dependent on temperature records, paleoclimate, thermometer or satelite. They are based on assumptions about climate physics, and simulate the consequence of those assumptions. If you want to show that the models are not accurate, then you need to show that the error of the models is larger than the internal variability of the climate. However, we can't measure the variability of the climate, no matter how good our instuments are, as there is only one stochastic realisation of true climate physics available (i.e. the observed climate on Earth). The best estimate we can get is the spread of the model ensemble, so we are back to the consistency argument again. Note if the climate models were perfect, the spread of the model runs would be a perfect characterisation of the internal variability. So any attempt to discuss the accuracy of the models without reference to the inherent uncertainty is fundamentally misguided. "You claim climate science is about making accurate LONG term predictions. These predictions need some accuracy to them in order to be useful as science." Yes, but we only know if they are accurate in hindsight, and we can only assess the accuracy of hindcasts with respect to the inherent uncertainty of the observations (not just the measurement error, but the uncertainty due to "weather noise"). Can you demonstrate that current climate models give inaccurate hindcasts (or forecasts of long term trends for older models)? "What is your iconic climate model prediction that has proven accurate by the test of time? When was that prediction made?" How about this one "Is that climate model still in use?" Of couse not. Steam locomotives are still capable of pulling carriages, but are no longer used due to a sequence of incremental improvements mean we can now do better. Climate models are no different, but the basic principles uesd now are the same as they were 30 years ago. "Disequilibrium" is indeed an odd term, and a bit of a non-sequitur as nobody mentioned it. The climate spends most of its time in a state of approximate, but not exact equilibrium, with the occasional flip between glacial and interglacial (equilibrium) states. "There is no real objective evidence that warmer is not better." It is the fact that there will be change that is the problem, as that will require adaption, which has economic and societal costs associated with it. If you live in Amsterdam or Bangladesh, you might argue that there is obvious evidence that warmer is not better, at least for you. "How do you think we should plan to stop China and the rest of the developing countries from using coal and burning wood? War? " Does that affect the science or whether the models are accurate? No. HTH (Hope That Helps) Dikran
  37. Daniel Bailey at 23:24 PM on 2 August 2010
    On Consensus
    Re: nhthinker Equilibrium is a relative term. In the context that for the past 6000-8000 years, the seasons and rains have a sense of stability to them, allowing for the rise of civilization and ordered societies. From that perspective, the globe has been in equilibrium climatically. Now science and our ability to measure change is sending danger signals. The world is transitioning into a new geologic epoch; a change we as humans have measurably and demonstrably aided. Indeed, evidence suggests that the climatic stability of this present interglacial has been in part ordered by the activities of man (cf. William Ruddiman's book Plows, Plagues, and Petroleum: How Humans Took Control of Climate here). In that same vein, debating the minutiae beyond a certain reasonable point becomes fruitless. Because no comparatives exist (to my knowledge) in the paleo record to the rate that we have injected a bolus of carbon into the world's carbon cycle. Tipping points, some of which we are aware and some not, clearly exist. The thing that scares me most is that I cannot bound the risk that the coming changes to the world's climate might put our species' existence at stake (systemic interactions due to drought, famine, pestilence, war, etc.). The fact that it is even a non-zero chance should be of concern to all. What to do about it is the point of this post. Not devolving into the weeds. We have raised ourselves up to our hands and knees from the weeds and see the trees for the first time now, and sense warning signs to the species. And we continue to operate with the presumption that we still have time to avoid the fate to which we are consigning ourselves. That presumption may be hubris. That also scares me. The Yooper
  38. The Past and Future of the Greenland Ice Sheet
    Both the mentioned papers talk about "mass balance" but unfortunately apparently don't include any discussion of the input side of the equation. Has there been any measurement of the amount of precipitation? Has it changed? Why?
  39. Glenn Tamblyn at 23:15 PM on 2 August 2010
    On Consensus
    andrewcodd "Is the duration of term of office and ergo microscopic period of accountability the detremining facor for not very sensible desicions on climate from governments? " Perhaps the more important factor is less the time horizons and cognitive dissonance of governments. It is the time horizons, cognitive dissonance and inability to look beyond the narrow 'what can I do in my life' perspective of individuals. Ultimately, governments are peripheral. They may enact the policies needed. But they don't determine the need for the action. We do. Until the populace give government the permission to act, government will not act. What does action mean? First break the dominant paradigms, then ask that question again. Otherwise action is limited by the paradigm and will be minor, token & ineffectual. To break paradigms, government needs our permission, nay, our directive, to do so. Until then they only act within the existing paradigms. So how do we mobilise the populace to say that we have to think outside the square, to ask what may be retained, and what must be sacrificed in order to avoid sacrificing everything. Like a ship in peril on the sea, the overarching question is; When should we take to the lifeboats? When should we start sacrificing parts of our lives and societies in order to avoid sacrificing our souls and everything. The captains of the world will never issue the Abandon Ship order if we do not give them our permission. And we are at the Abandon Ship stage Now. We can't save everything. We have to start deciding now what we sacrifice so that we can save some things. And as always, the Leaders Follow.
  40. Visually depicting the disconnect between climate scientists, media and the public
    Dappledwater ... that what a Stev W reckoned on a blog in reference to what happened on the Carteret Islands. May not be applicable in the case of Tuvalu, but maybe it is.
  41. 1934 - hottest year on record
    Tom... Whew! Relieved to know that since the US is only 2% of the globe it doesn't matter. I believe you may have missed a point too... the NCDC-NOAA has systematically lowered the early Weather Bureau records. But since it doesn't matter anyway, its not a problem I guess. Doug... These were not single-day records, but monthly records. The single-day records are, however, similar... 1895-2009, 40 states with record single-day extreme highs before 1955, only 8 extremes after 1975. It is curious that Meehle (your 'sophisticated' way to look at it) chose to look only at the records from 1950 onward. Might this be called sophisticated 'cherry-picking'? In choosing this period he ignored the 30 record states before 1950, 26 of which were set from 1921 to 1934. Furthermore, from 1954 to 1987 there were no state record highs broken at all... not one.
  42. Visually depicting the disconnect between climate scientists, media and the public
    Steering off topic again - John Chapman @36 - Tuvalu is essentially subsistence farming and has a declining population, where do you get the idea that the salt intrusion is from increased water use?. Inhabitants there, whom I've seen interviewed, regularly claim higher king tides and greater storm surges, are responsible for the salt intrusion. Seems reasonable given the photos I've seen of the inundation.
  43. On Consensus
    HTH, Not a very good defense. Most of Climate science relies on imprecise historic record on temperature by use of proxies. Modern measurements by satellites (both of the Earth and of the Sun) are immensely more accurate and precise in a scientific sense. The next 50 years will raise climate science closer to the precision of medical science- but it will still less, because of the lack of ability to control experiments and because the time periods required to analyze impacts. Science for measuring the heat content and flow in deep water is truly in its infancy. You claim climate science is about making accurate LONG term predictions. These predictions need some accuracy to them in order to be useful as science. What is your iconic climate model prediction that has proven accurate by the test of time? When was that prediction made? Is that climate model still in use? What we get told is that the dangers are too great to wait for the results to come in. We are told that the Earth's mechanisms can not cope and it is in "disequilibrium". Disequalibrium is a completely unscientific term. The Earth is never in equilibrium but instead, always reacting to changes that are occurring both inside the atmosphere and outside the atmosphere. Earth's equilibrium, if it had one, would be a deep ice age with a ability to sustain a very small fraction of the current level of human life and other life. Note that there were starts of a few interglacial period that were much warmer than the current temperature levels. There is no real objective evidence that warmer is not better. How do you think we should plan to stop China and the rest of the developing countries from using coal and burning wood? War?
  44. On Consensus
    Theory of Evolution and smoking I am amazed at how many young people I see smoking when there is so much medical evidence of its harmful effects . I like the 1984 syndrome too , Ive been to WUWT a few time an seen the doublethink that goes on there . Humans are very stange indeed
  45. On Consensus
    I dont think maniacs are the problem although newspeak references are very apt. Look at the green pages of any paper and they talk about the fur trade one day and global warming the next as if they are related in magnitude. People with an ecological conscience need to clearly demonstrate climate change is of unparalled critical importance with biodiversity and animal rights issues way way down the task list. Really climate change needs to shed its green feel trappings. We may loose a few supporters but theres a lot more to gain. Less hippies and more economists would be ideal.
  46. Dikran Marsupial at 21:47 PM on 2 August 2010
    On Consensus
    nhthinker wrote: "One expects 99.999999% accuracy from physics." This is not correct, for instance, Einstein apparently once said "As far as the laws of mathematics refer to reality, they are not certain, and as far as they are certain, they do not refer to reality.", and I think we can agree that he knew his physics. GEP Box (an expert on time-series prediction) said "Essentially, all models are wrong, but some are useful", in other words, we shouldn't expect any [mathematical] model to provide completely accurate predictions of the real world. For a concrete example, consider a double pendulum, like this one (shamelessly blagged from Wikipedia): Now the behaviour of a double pendulum can be modelled exactly by a few mathematical equations, but can physics predict the behaviour of a double pendulum with 99.999999% accuracy? No, because it is an example of a chaotic system; in fact, given a sufficiently long prediction horizon, physics can't predict the position of the pendulum with any skill at all. The double pendulum is rather apposite example, as the weather is also a chaotic system, which is why weather forecasts rapily loose any skill beyond a few days prediction horizon. However, climate is not the same thing as weather; climate describes the long term statistical behaviour of the weather (most often in terms of means or long term trends). Just because the weather is chaotic, does not imply that climate is also chaotic (and hence unpredictable). Again, the double pendulum can be used to demonstrate this is true as well. Consider a double pendulum, where the weight is made of iron, but this time imagine an electo-magnet placed to the right hand side of the pendulum. Physics still can't predict the exact path of the double pendulum, however it is able to predict that as the power to the electro-magnet increases, the position of the pendulum will be increasingly biased to the right. In this example, the position of the pendulum corresponds to global mean temperature (the further to the right, the higher the temperature) and the power to the electro-magnet corresponds to climate forcings (e.g. CO2 radiative forcing). Likewise, we can't predict the course of the weather with any real skill, as like the movement of the pendulum it is chaotic, but we can predict the effiects of a change in the forcing, in terms of trends and long-term averages. Particularly that if we increase the forcings, global temperatures can be expected to rise. Of course the physics of a global circulation model (GCM) is rather more complex, but the basic idea is the same - model the long term statistical behavior, not the exact course of the weather. As it happens, physics/statistics can actually do rather better than that, by using an ensemble of models, all starting from slightly different initial conditions, but with the same forcings. In physics this is known as a Monte Carlo experiment. In the case of the double pendulum, we would set of a number of simulations, with different initial positions and velocities of the two weights and let them run with exactly the same signal sent to the electro-magnet in each case. This would provide a distribution of values for the predicted position of the double-pendulum at the end of the simulation, describing which configurations are the most plausible and those which are not plausible. In this case, it would be expected to be skewed to the right, the more power applied to the electro-magnet, the more skewed the distribution. We can then form a credible interval, describing the smallest region that is expected to contain the actual position of the pendulum with 95% confidence. Likewise, climatologists routinely do the same thing by running many simulations of the future climate, and then take the mean (in order to average out the chaotic effects of the weather). They also form mult-model ensembles to average out the effects of uncertainty in our knowledge of the detailed physics of the climate. So how is that relevant to nthinkers post? Simple, it is pretty meaningless to talk of a climate prediction being accurate to an arbitrary level (such as 90%). The accuracy of the prediction can only be discussed relative to the stated error bars on that prediction. First we need to see if the observations are consistent with the models (i.e. do the observations lie within the spread of the model ensemble). They generally are (possibly because the error bars are often rather broad, recognising that there is inherent uncertainty involved in climate prediction). In science, theories (models) can't be proven right, they can only be demosntrated to be false (at least that is what Popperians would say). So if the observations lie within the error bars, then the model is as accurate as it can reasonably be expected to be. Anyway, this explains why climatology can be in the 4.5-5 bracket, even though the predictions made can easily be made to look wrong by confusing short-term weather phenomena (which the modellers don't claim to be able to predict) for long-term climate (which they do). HTH
  47. On Consensus
    JMurphy #12, the difference between AGW and evolution is that AGW will directly impact the people who currently deny its existence. It will be 'in their face' more and more as time goes by. 'Young Earth creationists' actually argue that the standard value for the speed of light is off by several orders of magnitude because it yields ages in the billions of years for distant objects... while everyone knows that God created the universe about 6000 years ago. This is, of course, pure madness disproved by satellite communications (which measurably travel at the expected standard speed), atomic energy, and a hundred other aspects of modern technology... but the creationists don't understand any of those things. They can't 'see' the speed of light directly and grasp it in any meaningful sense. AGW is different. People can see when the birds that visit their yard change over the course of a couple decades. When trees and other plants that used to grow near them no longer do as well. When the water from mountain runoff gets lower and lower every year. Et cetera. Sure, they can deny that these things are happening or that people are causing it... but as time goes by more and more of these changes will pile up and it will get that much more difficult for people to deny reality. What I worry about is the '1984 syndrome' where the denialist story changes radically over-night and all the deluded just accept that it has always been that way (e.g. 'we have always been at war with Oceana'). First deniers said that it wasn't getting warmer. Now it IS getting warmer, but it is a natural cycle that will reverse soon or just a minor trend which will never get very serious. When that proves false it'll probably switch to, 'God is punishing us for spurning his gift of oil by not using it all' or something equally mad... and some will believe it. However, right now that lunatic fringe IS the fringe. Most people accept evolution. Most know the world is not 6000 years old. And within the next decade anyone remotely sane will accept AGW as reality... because the changes are speeding up and getting serious. So the primary worries I see are the lunatic fringe getting stronger (as they have been) and/or it taking too long for people to wake up.
  48. Berényi Péter at 21:02 PM on 2 August 2010
    Visually depicting the disconnect between climate scientists, media and the public
    kdk #39 I reckon it's pretty clear that he means extrapolating on the linear trend of recent history I don't think so. He also writes: "will result in sea level changes unlikely to have comparators in the paleo record". In my vocabulary it means he is considering something unprecedented in the paleo record. this kind of behaviour is entirely possible given the right situation Yes. But the right situation is not given. We have no lakes comparable to those monsters.
  49. 10 key climate indicators all point to the same finding: global warming is unmistakable
    stmwatkins #122, it should also be stressed again that GCMs are only one of three (or more?) lines of evidence indicating the degree of warming from anthropogenic sources. Paleoclimate research has been conducted to determine how past swings of carbon dioxide have impacted past temperatures... thus giving us some idea of the impacts the CO2 increase we are currently causing will have. Also, direct measurements of current changes in CO2, temperature, and feedback effects like water vapor and albedo are used to compute the anthropogenic impact. So even if you were to conclude that the GCMs are complete nonsense which somehow match the paleoclimate and current direct measurement data by random chance... it wouldn't change the overall arc of climate science at all. The claim that AGW is 'all based on computer models' is fiction.
  50. Visually depicting the disconnect between climate scientists, media and the public
    BP #38 I reckon it's pretty clear that he means extrapolating on the linear trend of recent history. Stripped of the innuendo, your post informs us that this kind of behaviour is entirely possible given the right situation :-).

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