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Comments 104501 to 104550:

  1. Naomi Oreskes' Merchants of Doubt Australian tour
    JohnHarrington. That sounds less like "how science works" than how any workplace can go wrong. How many people do you hear grumbling about dopey or biased or bullying management in any activity? Quite often there's something in it. Two things to consider. One, it may be true, but not nearly as often as unsuccessful people blaming others for their own failures. Two, the fact that one person / manager / senior scientist is a pain in the neck or any other part of the anatomy says more about that person than it does about the field of endeavour. What this woman said might, possibly, be true about the person she was dealing with or about that particular sub-specialty. It says nothing about the larger field of science generally and it certainly does not lead to conclusions about greed or Nazism or Lysenkoism or corruption or any of the other general criticisms of science. (My personal view is that anyone who plays the Nazi card automatically deals themselves out of the game.)
  2. Naomi Oreskes' Merchants of Doubt Australian tour
    Excuse me if this is too off the topic. I really don't know where else I might post this. I was debating someone at a party recently who opined that "science is about dominant factions of science bullying those who disagree". The person saying this claimed to have a PhD in archeology and to have escaped the field in part because a rival scientist got her in trouble with a foreign government, which caused passport trouble, simply because she disagreed with this scientist's hypothesis about horse domestication. She went on to compare "modern science" to science done in Nazi Germany and to suggest that peer review was a sham, made venal by government monies in science. I'm not a scientist, as I was forced to admit, and this made her seem like the authority who was giving me the truth about how "science really works". I wonder if any practicing scientists posting here could comment on this view of "modern science".
  3. Are ice sheet losses overestimated?
    One thing is clear from this excellent summary. Ice loss in polar regions is occurring and getting faster. No surprise to anyone. It also focuses attention to the fact that we need (and presumably will get) more information, particularly on the extent to which ice loss is now and will in the future contribute to the most dangerous aspect of global warming – rising sea levels.
  4. How significance tests are misused in climate science
    Dikran (@37), Perhaps I just need to see an example of Bayesian significance testing done right to understand the way you and Dr Anbaum think this should be done. "one of the most important benefits of the Bayesian approach is that it gives mechanism to properly incorporate the fact that you know you don't know something, by assigning a non- or minimally-informative prior on it and marginalising it out of the analysis" Does a Bayesian analysis with a minimally informative prior often lead to a different result than a frequentist approach? I must confess that my knowledge of Bayesian statistics comes entirely from studying data mining/machine learning, so there may be a side to this I'm missing from not having studied more stats. In that class one thing we were taught is that if you don't really know the prior the most common thing to do is assume it's 50/50. Is that the sort of thing you mean by minimally informative prior? "Bayesian conclusions are only as strong as the priors used, if you could show the priors were unreasonable then you could reject the result of the test (and the paper). If you can't question the prior, you are logically forced to accept the result of the test." It still seems to me to be a question of what the point of the work you're doing is and what you can add to the body of knowledge. Let's assume I am an expert in dendrochronology, and I core a few trees in my backyard. Now I need to calculate a prior probability for observing warming in that data set. One way I might do that is by looking at the evidence from atmospheric physics and other areas outside my expertise and decide how likely this should be, but why would I be the one to do this when that really isn't my field and I'm likely to screw it up, I just know all there is to know about tree rings? Or are you suggesting I use a non-informative prior? Let's say I did the full analysis and found that with 99% confidence given changes in various forcings and our range of sensitivity estimates the data should show an upward trend of .15 degree/decade or more. And then I did some calculations on my little data set that any frequentist would sneer at and calculated a posterior probability of 99% for my hypothesis. Have I used my knowledge as a dendrochronologist to contribute anything to the state of our knowledge about climate? My result comes from my prior calculation, the part of my work I'm least qualified to do, meanwhile the actual data I've collected is superfluous (and I should have collected more of it, as a frequentist statistical significance test would have told me). I do think a Bayesian analysis by someone who was an expert in such things that combined varous lines of evidence from many subfields of climate research and tried to establish probabilities for various climate related hypothesis would be an interesting work, but it's not reasonable or useful to expect every researcher to do this in the process of establishing their result, and indeed Dr. Anbaum's research shows pretty conclusively that most would not be competent to do it. If on the other hand you want most scientists to replace frequentist significance tests with Bayesian tests with non-informative priors to show they've learned at least that much about stats and know what their confidence values mean, I guess I'm okay with that, but I doubt it would change anyone's results much beyond changing the confidence values by a small amount. I do think scientists should not put their confidence values front and center as if they are the results, better to focus on estimating the magnitudes of effects, but do some kind of confidence calculation just to keep yourself honest and make yourself less likely to publish garbage. But if you think that's the main value that comes from confidence calculations in science (and I do) rather than determining whether we should be 96% certain or 99.3%, then a frequentist approach will generally work okay and if the result is your paper leads people to believe that climate sensitivity is 3.2 when you really do have good reason to believe it is 3.2, then your paper isn't particularly misleading just because there may be a better way you could have done your confidence calculation.
  5. Naomi Oreskes' Merchants of Doubt Australian tour
    quokka... This is exactly my point as well. We would all love it if we could jump on a jet airplane that was burning algae based bio-fuel that was being produced at a cost comparable to current jet fuel. I'm sure Al Gore would be the first to book limousine service from a company who had an all electric fleet. We are not there. (We don't have the vegetables for our veggie diet.) We need people like Oreskes flying around doing these tours to promote her book. We need politicians flying to Copenhagen for such events. To stop - or even slow this process down - is to stop the process of addressing this issue.
  6. Naomi Oreskes' Merchants of Doubt Australian tour
    johnd: That is the real problem coming that people should be wringing their hands over. This seems like a false dichotomy. Acknowledging the problems you mention does not require us to see AGW, or any other problem, as less than "real." Also, "wringing their hands" has a rather contemptuous sound. Saying something like "a problem people also need to address" might be a bit more constructive.
  7. Naomi Oreskes' Merchants of Doubt Australian tour
    #16 KeenOn350 There is a carbon cost on just about any activity - from eating your lunch to building wind turbines or nuclear power stations. The point surely is to spend that carbon wisely. As far as I am concerned, the trivial carbon costs associated with Oreskes tour is a very wise expenditure of carbon indeed. If Oreskes, Hansen and other outstanding individuals want to fly around the world 100 times a year in the political fight against AGW deniers and that activity can bring forward an organized collective effort to reduce emissions by even a tiny amount, then that carbon cost would be repaid by orders of magnitude. Youtube videos are no substitute for physical presence. Why do people like live music? Why do we still have teachers in classrooms?
  8. Economic Impacts of Carbon Pricing
    Eric (34), if you are a "skeptic" about government spending, then you should equally advocate a cap-and-trade bill or a carbon tax while demanding tax cuts, not just scrapping economic action against climate change altogether. "Government wastes money" is a poor excuse and just amounts to a simplist libertarian pirouette against taking action against global warming just because the Gov't is involved. Reasonable libertarian-leaning economists support cap-and-trade (for example, Tyler Cowen). There are even some cap-and-dividend proposals which involve directly handing over the money to the citizens, therefore deflecting your critique. One small remark: "> The IGEM model is an outlier because it assumes when the price of energy (and other goods and services) rises, people will respond by choosing to work less than they otherwise would (EDF 2008). This is a counter-intuitive and illogical assumption, since increasing costs generally result in people working more to increase income correspondingly" Actually, this is a bit more complex. Economic theory says that price changes have _both_ a "substitution effect" (if working is less useful, people work less) and an "income effect" (if work "pays less", people will try to work more in order to "offset" its effects). Both effects do exist in the real world, and which effect is stronger depends on a lot of things and it is an empirical question rather than a theoretical one. AFAIK some economists find a significant substitution effect in the economy as a whole (Prescott) while others report a smaller one. I don't know in depth what does the literature say, but I wouldn't go so far as to declare substitution effects "illogical" or "counter-intuitive". They're just as real as income effects, the real question is whether they are big or small. This is relevant for a number of reasons beyond climate change (tax policy, for example).
  9. Naomi Oreskes' Merchants of Doubt Australian tour
    Argus wrote : "Is there any follow-up report available yet?" Well, to stop going further off-topic, I can start you off and you can then find out further information for yourself hopefully : Brick Kilns
  10. Naomi Oreskes' Merchants of Doubt Australian tour
    Re: CBDunkerson (8:05 am) I like to think that there will be a future civilization, when global population has been stabilized at around 1.5 - 2 billion, and most energy is green, and lifestyles are equitable globally (i.e. most residents of future Africa, India, etc., have a lifestyle comparable to most residents of the future USA), and that those lifestyles for all will be, in many ways, similar to those of today. I like to think that in the very near future, we will take some control of our destiny in a more rational fashion, to deal realistically with the crises we face (of which climate disruption is only one). I like to think that we may have a rough landing, but it won't be a crash. But meantime - planet Earth, we have a problem. The scale is greater than that of WW II, the threat may be greater than (or may include) WW III. In WW II, people accepted the need to constrain their lifestyles and consumption habits to address their problem. (They also accepted a lot of government controls - voluntarily, understanding the need.) I see no way that we can address our multiple problems effectively without accepting similar constraints for the near future, given that we have wasted 40 years or so. Had we started to address the two major problems of clean energy and population growth effectively in the early 1970's ( when both problems were already in evidence), then I would be more inclined to agree with you. Given where we are today, and what seems to be in the international plans for the near future (not much!), lifestyle changes will be coming. As John Holdren has said - "We basically have three choices: mitigation, adaptation and suffering. We're going to do some of each. The question is what the mix is going to be. The more mitigation we do, the less adaptation will be required and the less suffering there will be." Right now we seem to be opting for the suffering - i.e., a serious and forced change in lifestyles, which will, before long, affect those of us in the USA and Canada, as it is now affecting many in other parts of the world.
  11. Naomi Oreskes' Merchants of Doubt Australian tour
    JMurphy (#23): "To ensure the conference will be climate neutral, the Danish Government, ..." That is good news, thank you, I did not know about those plans. I hope they went through with the programme, and that it worked out as it was planned a year ago. Is there any follow-up report available yet?
  12. Ice-Free Arctic
    Berényi Péter comparing summer ice extend to visibility in Hong Kong doesn't tell much about the causality between the two. Probably there's not. More relevant could be meaurements BC concentration in ice cores. It's in Central Greenland, not over the arctic ocean, but it clearly shows (fig 2a) that BC deposition there went through a quite large peak around 1910 and then declined. In the last decades, though, it's slowly increasing again, but still well below the peak.
  13. Are ice sheet losses overestimated?
    Stephen@5. I doubt we can 'protect' science, scientists or their individual publications from misuse or attack. I'm afraid it's really for us and the scientific community to support wherever possible. When we're stuck walking in the rain, we share the umbrellas, we keep trudging on and we make maximum use of every little bit of dry shelter with gratitude. And we keep each other's spirits up.
  14. Naomi Oreskes' Merchants of Doubt Australian tour
    CBDunkerson at 08:05 AM, whilst some may feel content to continue existing lifestyles if energy production changes to low CO2 alternatives, what goes hand in hand with energy usage in lifestyles is that other form of energy, namely food. This is perhaps the real problem that should be addressed as so far, unlike the nuclear option for power generation, there is no alternative for the essential nutrients that are stripped from the soil to produce the food, be it meat or vegetables. So there should be no thought of being able to continue an existing lifestyle by phasing out fossil fuels if half the food that leaves the farm gate is going to be continued to be wasted by an indulgent lifestyle that is partly reflected by increasing obesity in the developed, mainly western world. That is the real problem coming that people should be wringing their hands over.
  15. Naomi Oreskes' Merchants of Doubt Australian tour
    KeenOn350 wrote: "This is precisely the question - who will begin to implement and to demonstrate the lifestyle changes we need? And when?" You are proceeding from a first assumption, that we must make significant lifestyle changes, which I do not agree with. In reality that is only one theoretical option, and in my opinion not a very plausible one. It seems far more likely that we will convert most of our energy production to low carbon emitting alternatives and continue with our current lifestyle largely unchanged.
  16. Are ice sheet losses overestimated?
    Great post, Robert. This is a really handy summary of where things stand right now.
  17. Naomi Oreskes' Merchants of Doubt Australian tour
    Argus wrote : "Another example of mixed messages was the Copenhagen meeting a year ago." It isn't perfect, and shouldn't be used as an excuse by anyone to do nothing at all (a la "Gore flies everywhere and burns loads of electricity in his mansion(s), so why should I do anything ?" - um, why should we judge anything by what he, or any other individual, does ?), especially because of the following : An initial estimate of overall emissions result in a figure of 40,500 tonnes of carbon dioxide. To ensure the conference will be climate neutral, the Danish Government, in partnership with Bangladesh and the World Bank, has decided to replace outdated brick kilns in Dhaka. It will see the heavily polluting, existing kilns replaced by 20 new energy efficient ones, which the Danish Energy Agency calculates will cut more than 50,000 tonnes of CO2 emissions each year and improve air quality in one of the world’s most polluted cities. The Danish government has set aside 0.7 million euro as part of this year’s state budget for this purpose. Fact sheet: Minimising the Copenhagen carbon footprint
  18. forensicscience at 07:12 AM on 16 November 2010
    Naomi Oreskes' Merchants of Doubt Australian tour
    Re #18, I cant see what that has to do with ACC. We burn 30 billion barrels of oil per annum (4.5 billion tonnes) so its hardly an issue now is it?
  19. Naomi Oreskes' Merchants of Doubt Australian tour
    Re: DBailey (18) There is some merit in what you say about networking, physical presence, etc. given our current lifestyles and expectations . This is precisely the question - who will begin to implement and to demonstrate the lifestyle changes we need? And when? A tour such as this would have been improbable 50 years ago, and virtually impossible 75 years ago. (I expect that sometime in the not-too-distant future, it will again become very unusual, unless we find much greener air transport.) A book would still sell (or not), based on recommendations by friends, local advertising, intrinsic worth of the contents, etc. People would not expect personal meetings/glad-handing - this is Madison Avenue creating the norm in our current (unthinking) world. Inter-continental networking in the past was done by snail-mail. People networked based on their ideas, on paper. Today we have e-mail and Skype - much more accessible. The expectation of personal presence for networking is in large part a consequence of easy air travel. We have to revise our "normal" expectations in this "post-normal" world. Live tele-presenting is still somewhat unusual. It could be advertised positively, as low-impact communication with the author. Emphasis on the Skype Q&A...pose your own questions live! As to the question of how many converts Dr. Oreskes' personal presence will bring on board, I wonder to what extent she will be preaching to, and meeting with, the "converted", as opposed to the doubters, or the deniers. Entrance and exit polling at the presentations might be an interesting study. Re: RHoneycutt (20) Right now, there are lots of vegetables available. The shortage of vegetables (and flights to Oz) are in the future. I am just trying to suggest that we can start to demonstrate that people can live quite happily and healthily while eating a lot less meat.
  20. Naomi Oreskes' Merchants of Doubt Australian tour
    All the comments of "walk the walk" in relation to people using carbon emitting forms of transportation is a bit like telling someone they should become a vegetarian at a time where there are few vegetables available. Yes. Let's move toward solutions. Yes, use reasonable low carbon options where available as they become available. But let's not kid ourselves that it's currently possible to be productive in the quest to reduce CO2 by eschewing all carbon based transportation.
  21. Naomi Oreskes' Merchants of Doubt Australian tour
    #10 @humanityrules What's your problem with "AGW isn't true because I like Oreos ... AGW is true because (a large list of real causes behind an AGW that is true)"? Why your "There seems to be no logic in this comment. What have clouds got to do with DDT? Guilt by association???" looks like it works with an "is" in the assertion you criticize instead of the "isn't" that is indeed written? Why don't you explain it again -including the original "isn't"-?
  22. Solving Global Warming - Not Easy, But Not Too Hard
    actually thoughtfull: "How many of us are using renewable energy right now?" I use a green electricity tariff (i'm all electric). I have managed to reduce my energy consumption by about 60% by just doing a few simple things which haven't had a big impact to the quality of life. I would have solar heating panels if it weren't for the big tree in the neighbours garden that blocks the Sun, also cost is an issue for me right now. actually thoughtfull: "Electricity is 20% of the energy consumed. Because of the coal in the mix, it accounts for 1/3 of the carbon emissions." Yeah but in the UK, coal is 30% of the electricity mix which equates to 60% of the electricity emissions. In the US coal is something like 70% of generation capacity so must be something like 90% of electricity emissions. The other point is that electricity is likely to be the main source and means of conveying energy, so it may not be the majority chunk now, but it certainly will be in the future.
  23. Naomi Oreskes' Merchants of Doubt Australian tour
    Another example of mixed messages was the Copenhagen meeting a year ago. 1200 limousines (a negligible number of them electric or hybrid) were used. The prominent guests used 140 private jet planes to get there, in addition to all the regular airplanes that transported the 15000 guests and journalists. We can only dream about the buffés with caviar and lobster and so on. Of course the top guys want to live in their usual luxury even if it is a climate meeting.
  24. Naomi Oreskes' Merchants of Doubt Australian tour
    Re: KeenOn350 (17) Appreciate the perspectives and the personal experiences with green telepresenting. But do not underestimate the power of networking and physical presence that in-person tours such as Dr. Oreskes is performing now have. Much interaction goes on behind the scenes that also has value, interaction that would not occur in a green tour. If a physical tour, such as is being undertaken, gets the job done then I'm OK with that. For there are many who would not attend such a program without a live speaker present. And if the glad-handing at a book-signing is what it takes to convince someone, then I'm OK with that, too. The Yooper
  25. Economic Impacts of Carbon Pricing
    "When a price is put on carbon emissions [government sells allowances], it creates a revenue stream." True. "The funds which are generated from the carbon price can be distributed in any number of ways – usually through reductions in other taxes, investment in research and development of 'green' technologies, funding of energy efficiency programs, etc." Not necessarily. The money can also be wasted, here is a libertarian response http://townhall.com/columnists/RobertMurphy/2009/05/02/the_cost_of_cap_and_trade/page/full/
  26. Are ice sheet losses overestimated?
    This is an excellent article. Not being a glacialogist, it really makes it much clearer to me what is behind all these estimates and explains well the bases of differences. Thanks! It also makes it clear how hard it is to do science in the current atmosphere of hypervigilism (and hyperhypism) we are in. As described in this article, the Wu paper becomes a call for better GPS coverage in central Greenland, which is a good thing if you want to lay out priorities in future efforts. However, the way it has been spun in some blogs (and by some on this site) you'd think it was the nail in the coffin of scientific credibility regarding climate change rather than part of a real debate about how best to quantify what is universally acknowledged to be a decline in ice mass on Greenland. It must be difficult knowing that something you will publish for perfectly good objective scientific reasons might get picked up by the vortex of public debate, stripped of all scientific context and flung back at you with amazing force and some new originally untended political bias. How can we protect scientific debate from this kind of distortion?
  27. Economic Impacts of Carbon Pricing
    Here's a different way of visualizing the costs of cap-and-trade that shows just how small they really are: http://akwag.blogspot.com/2009/09/visualizing-costs-of-cap-and-trade.html
  28. Naomi Oreskes' Merchants of Doubt Australian tour
    Let me preface these observations by saying that I have seen several video presentations by Dr. Oreskes on the Web, and admire her work. Nevertheless, I feel there is something to question about this tour. A few months ago, our community green group put on a presentation of the film No Impact Man, followed by a Q & A session with Colin Beavan. The Q & A was done by Skype, and worked very well. We had personal interaction with Colin, we could see him on the big screen, even though he was not physically present. Environmental impact - very low! Results - very satisfactory. Information exchange - just as good as it would have been by personal travel. I fully realize that individual efforts to reduce carbon footprint/climate impact (CFL or LED bulbs, driving a small car, cycling more, etc.) will be insufficient to curb climate disruption. However, I believe that such efforts are necessary, along with more sweeping measures on regional, national, and international scales. Partly it is a question of changing attitudes, and reinforcing that change It is unfortunate that the IPCC reports, and the general community of those addressing the problem of CO2 emissions, refer to the danger of "BAU" (Business as usual). In reality, the danger derives from "LAU" - Living as usual - which more expressly includes the fact that we must change our lifestyle practises, as well as our practises at work. I find it ironic that Naomi Oreskes is flying half way around the world, and then all over Oz, to do something that could just as well be done from her home, with perhaps a minor inconvenience due to time zones. I find it ironic that such organizations as the presenters ( Climate Change Research Centre, The Global Change Institute, The Monash Sustainability Institute, The Melbourne Sustainable Society Institute) have invited her to do this. This is sustainable? This is change? Or is this unthinking BAU/LAU which could easily be changed to a more sustainable format? One factor that we must include in any effort to combat climate disruption is better use of our amazing modern technology. People purporting to be concerned about climate impacts must begin to walk the walk - talk is not enough - and do so in obvious ways which make a public demonstration of the changes we can implement easily. Is it worth the impact to have Dr. Oreskes flying all over, so that a few people can actually shake her hand, and get a personally autographed copy of her book? ------- A small final point - in her all her major video presentations on the web, Dr. Oreskes is drinking bottled water. Another unnecessary modern convenience with disproportionately high impact. Check out The Story of Bottled Water. I do hope the presenters at these sessions will at least provide her with a glass of tap water, or a re-usable water bottle filled with tap water, instead of the pre-bottled stuff, especially if she will be on a video which will then be widely seen. ------ Enjoy the tour - but consider the alternatives....
  29. Ice-Free Arctic
    James Hansen is well known for saying that controlling black carbon is one of the lowest hanging fruits in controlling AGW. For those who claim the IPCC goes only after CO2 this is a clear counter example of scientists trying to identify the cheapest fixes to go after first. That said, even with black carbon controlled, without controlling CO2 the ice will all melt out. We need to control as many sources of warming as possible.
  30. Naomi Oreskes' Merchants of Doubt Australian tour
    Just a comment to HumanityRules #10: (BTW Argus you seem to be falling for the same fallacy with your linking of Nazism and Communism. These are both historically specific movements, both require critiques independant of each other.) What you are referring to here is not my opinion; it is part of a quoted example of a faulty argument, borrowed from: en.wikipedia.org/wiki/Guilt_by_association
  31. Ice-Free Arctic
    #68: "The particulate load that China adds daily to the Arctic" #70: "The teleconnection between Chinese soot and Arctic melt is undeniable." That this soot largely originates in the burning of coal is proof that anthropogenic input is real and of significant, measurable magnitude. If this soot is moving to the Arctic, so are the exhaust gases which are produced with the soot. To verify this conclusion, look at the significantly higher average annual CO2 concentrations in the Arctic: compare BRW, ALT, ICE, OSM, PAL, MBC, ZEP to MLO. Further verification comes from Fisher et al 2010, who traced combustion gases via CO (monoxide) monitoring using data from both aircraft and the AIRS satellite: We find that Asian anthropogenic emissions are the dominant source of Arctic CO pollution everywhere except in surface air where European anthropogenic emissions are of similar importance. So if soot, then CO and CO2. And that is melting Arctic ice.
  32. Naomi Oreskes' Merchants of Doubt Australian tour
    Re: jsam (12) In HR's defense, he did not fire the opening salvo needed to invoke the Godwin rule. He was, however, caught in the resulting firefight. The Yooper
  33. How significance tests are misused in climate science
    Re: HumanityRules (43) We all have bad days; I certainly still have my share. :) Of course, just how bad is a matter of degree; how often, a matter of conjecture (speaking of my bad days, no-one else's). ;) The Yooper
  34. Naomi Oreskes' Merchants of Doubt Australian tour
    Argus, #8 This is a case of inductive logic ... X had used standard argument A and standard B in denial of demonstrable scientific propositions several times before. Inductively, X is also wrong about P (global warming) and this has been shown to be the case. The point is that argument A and tactic B are used continuously and repeated ad nauseam in and by the popular media, even after they have been refuted scientifically. In a way, that is part of tactic B. X, in fact, left the realm of science long ago, and entered the realm of the patron saint of marketing, P.T.Barnum. Barnum said "There is a sucker born every minute". In the Barnum world, every unprincipled tactic is justified to gain the desired result. This may be stronger than the way Oreskes puts it, but it is my interpretation. X may even have passed away, but his/ her successors, the Legion of X, are repeating his/ her arguments and tactics. Inductive logic tells us that X (or his/her Legion of Successors) are wrong but will be successful for a while. The point is how long will their tactics of delay postpone the inevitable?
  35. How significance tests are misused in climate science
    32.Daniel Bailey We are discussing n=1 papers here but I accept your criticism, I over-stated the point. We're all capable of mistakes, as Maartens work suggests. Maarten(n=1) I don't suppose you want comment to what extent you agree or disagree with the statements contained in this link?
  36. Naomi Oreskes' Merchants of Doubt Australian tour
    By Godwin's Law HumanityRules has lost the argument. See http://en.wikipedia.org/wiki/Godwin's_law. More seriously, the book is worth reading. There are also some very good, if long (60 minute) Youtube clips. Real skeptics have, of course, viewed those before posting. On the other hand when person X tells fibs A and then B it is perfectly reasonable to question whether his statement C is a fib or not. Skeptics note trends.
  37. Naomi Oreskes' Merchants of Doubt Australian tour
    Re: HumanityRules (10) Much of what the moderator had to say in this response to Argus above also applies to you as well. I suggest you read the book and then form an opinion of it. That would be the skeptical thing to do. The Yooper
  38. Dikran Marsupial at 00:58 AM on 16 November 2010
    How significance tests are misused in climate science
    Hi Maarten, I fully agree the p-value can't be used to draw a fully objective conclusion; it is a subjective choice to disregard the null hypothesis based on a convention/tradition amongst frequentist statisticians (Occam's razor being a large part of the motivation) - nothing more (I checked with a frequentist colleague before I wrote that ;o). The distinction between rejecting and negating the null hypothesis is the key to the point I was making. Essentially we need to employ a form of words that emphasises the fact that we are chosing (not to) accept the null hypothesis, rather than that we have established that it is (not) true. When I was taught stats, that was the motivation given for saying "we reject the null hypothesis" rather than a positive statement about the alternative hypothesis or claiming that the null hypothesis is false. Essentially rejecting implies a choice, rather than a rational necessity. In short - I agree! BTW, the p-value fallacy doesn't just appear in science, I have seen this error made in statistical methodology papers I have reviewed. It certainly isn't limited to climatology!
  39. Naomi Oreskes' Merchants of Doubt Australian tour
    Response to 4.Argus In an attempt to refute Argus' accusation of guilt by association you immediately repeat the idea. "Her point is that the people who are skepticial towards AGW are the same people who used the same arguments against other areas of scientific consensus." You cannot right off all skeptics as Fred Singers, you lose credibility by suggesting such a thing. It would be like me suggesting all climate scientist have the same agenda driven position as James Hansen. Taking the details here at face value Singer essentially seems to be an anti-state libitarian who is oppposed to regulation against industry, it seems like the only thing that links all these issues. Not all skeptics are coming from this position, I know this for a fact. Even if this is true it's still only right that Singers ideas are engaged, it shouldn't be so difficult if "AGW is true". People ultimately have the right to dissent no matter how unpleasant (or pleasant) they are. But then I'm an old-fashioned democrat. "AGW isn't true because the skeptic arguments are similar to skeptic arguments against DDT, etc." There seems to be no logic in this comment. What have clouds got to do with DDT? Guilt by association??? (BTW Argus you seem to be falling for the same fallacy with your linking of Nazism and Communism. These are both historically specific movements, both require critiques independant of each other.)
  40. How significance tests are misused in climate science
    Re: Maarten Ambaum Thank you for taking the time to shed some light on your paper. It's appreciated. The Yooper
  41. How significance tests are misused in climate science
    Dear Dikran (Re post 39) Perhaps I misunderstand you and Tamino, but a low p-value cannot objectively be used to reject a null-hypothesis; it simply does not contain the required information to do so. I formalize this in my paper, if you like to know more. On the other hand, a high p-value indicates that the presented evidence is easily consistent with the null hypothesis. This is not evidence that the null-hypothesis is true; the evidence could also be consistent with the alternative hypothesis. A significance test simply contains no information either way. Using Occam's razor we can then conclude that there is no evidence for our hypothesis, so we better stick with the null-hypothesis. It is Occam's razor that makes the argument here, not the significance test. Maarten
  42. Dikran Marsupial at 00:01 AM on 16 November 2010
    How significance tests are misused in climate science
    The terminology used in reporting the results of statistical tests is indeed a thorny issue. Taminos comment that "it merely negates the null hypothesis.", would have been O.K. if he had instead written "is enough for us to reject the null hypothesis". The difference, while subtle, is very important; "negating" the null hypothesis is a statement that the null hypothesis is false, while "rejecting" the null hypothesis is merely a statement that we have made a subjective (if perhaps very reasonable) choice not to believe the null hypothesis based on the evidence - but stops well short of saying that it is false. Essentially it is only a convention that we "reject" the null hypothesis if the p-value falls below some critical value (which is also a subjective choice) - nothing more. The two phrases we should use would be something along the lines of "we can reject the null hypothesis" or "we are unable to reject the null hypothesis" - the frequentist test doesn't really give a basis to make any statement about the alternative hypothesis (note the alternative hypothesis doesn't actually appear in the frequentist test - so perhaps that isn't surprising!).
  43. Economic Impacts of Carbon Pricing
    Very good topic, btw. About time.
  44. Economic Impacts of Carbon Pricing
    Ok, now a derogatory comment on my own country, Brazil. Back-of-the-envelope bill: stop deforestation now, effectively cutting down 1994 emissions by some 20-30% immediately, with very marginal impacts to national GDP (logging in the Amazon is about 0.07% of the national GDP). Here's our emission inventory. Unfortunately in Portuguese, but the wrap-up graph on the last page is understandable with minimal google translating work.
  45. The Skeptical Chymist at 23:54 PM on 15 November 2010
    Are ice sheet losses overestimated?
    Thanks for a well explained post Robert. Solving these sorts of "mysteries" is part of the reason us science geeks enjoy science.
  46. Naomi Oreskes' Merchants of Doubt Australian tour
    Argus, I think the larger argument is that just as these efforts at attacking science and confusing the public had some success in past incidents (tobacco, asbestos, evolution, et cetera) so to are they in part responsible for the 'debate' over global warming. This site includes dozens of examples of 'skeptic' arguments which are provably clearly false... doubt has been created by the same deceptive tactics used in the past attacks on science Oreskes and Conway identify. No, that does not mean that all 'skeptics' are being deliberately deceptive or that all 'skeptic' arguments are wrong. However, it does mean that the discussion has been poisoned by deliberate misinformation. Which logically should lead everyone interested in the truth to want to identify provably false arguments and shut them out so we can deal with these issues from a foundation of reality.
  47. Naomi Oreskes' Merchants of Doubt Australian tour
    Thanks, tobyjoice: "What can you deduce from the foregoing?: - Most likely that I should not trust Mr X, and now I do not have to read that book. But are all "the people who are skeptical" wrong because Mr X (and Y and Z) is wrong? And are all "the people who are skepticial towards AGW" today, "the same people who used the same arguments against other areas of scientific consensus" ?
  48. Miriam O'Brien (Sou) at 22:44 PM on 15 November 2010
    Naomi Oreskes' Merchants of Doubt Australian tour
    I haven't read the book yet, but listened to Dr Oreskes on the ABC today. One of the points she made was that this tiny group of people appeared to be in it for ideological reasons rather than for monetary gain. They appear to be some sort of anarchists (my interpretation not Oreskes) and against any government guidance let alone intergovernmental cooperation or intervention. The other point was that they used their scientific qualifications and position of influence to try to boost their credibility. However none of them are specialists in the areas they criticised. In effect they are just Joe Bloggs. In fact it's worse, because they are peddling falsehoods, whereas Joe Bloggs knows that smoking tobacco carries high health risks, the earth is warming and the climate is changing.
  49. How significance tests are misused in climate science
    PS: I would like to highlight Tom Dayton's excellent contribution (no 16, above - I don't know how to include internal links - sorry). I agree very much with what he says. But may I just add that significance tests are perhaps not as innocent as he makes them out to be. Indeed, they are usually only a small part of the evidence, but I have been involved in discussions where an important part of the argument was whether a certain link, as measured by linear correlation, was "significant" (in the statistical meaning). This was very much an instance of explorative data analysis, where some link was posited, with only tenuous indications this link should be there, and where significance tests were an important part of the argument. Interestingly, that claimed link has now become part of mainstream climate literature (I am referring to "annular modes" which appear to indicate a connection between Atlantic and Pacific pressure patterns) and a large number of people have by now stopped to worry whether this implied link is really present. This is a feature of significance tests in general: perhaps many people do not mean to say that a low p-value is evidence for their hypothesis, but by publishing the low p-value along with phrases such as, "this or that effect is significant at the 95% level" certainly seems to imply that that want to use these statistics as positive evidence at face value.
  50. Dikran Marsupial at 22:26 PM on 15 November 2010
    How significance tests are misused in climate science
    Eric L @ 18 I strongly disagree that scientists should not bother with Bayesian statistics, especially in the case of statistical significance tests. There is rather more to Bayesianism than Bayes rule (which is a fundamental law of probability whether Bayesian or frequentist); the very definition of what a probability actually is, is an argument in favour of the Bayesian framework in this case. The problem with frequentist approach to statistical significance tests is that they fundamentally cannot assign a probability to the truth of a hypothesis, because a hypothesis is either true or it isn't, its truth is not a random variable and has no long run frequency (the frequentist definition of a probability). Unfortunately the probability of the alternative hypothesis being true is exactly what we want to know! Fortunately the Bayesian definition of probability is based on the state of knowledge regarding the truth of a proposition, so the Bayesian framework can directly assign a probability to the truth of a hypothesis. Generally in science it is best to carefully formulate the question you want to ask, and then choose a method that is capable of giving a direct answer to that question. As such the Bayesian approach is perfectly respectable, if not preferable. The frequentist approach can only give an indirect answer, telling you the likelihood of the observations assuming the null hypothesis is true, and leaving it up to you to decide what to conclude from that. Most of the problems with frequentist statistical tests lie in mistaking the indirect answer to the key question for a direct (Bayesian) one. The Bayesian approach is more than a means of aggregating evidence; one of the most important benefits of the Bayesian approach is that it gives mechanism to properly incorporate the fact that you know you don't know something, by assigning a non- or minimally-informative prior on it and marginalising it out of the analysis. For instance, if you want to model the impacts of climate change, it is incorrect to assume we know the exact value of climate sensitivity (for instance by picking the maximum likelihood value), instead we should integrate it out by computing an average of the impacts for each value of climate sensitivity weighted by its plausibility according to what we do know. "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." In this case, the Bayesian result exactly coincides with that from the frequentist approach. The only difference is that the Bayesian approach allows you to formulate the question in terms of an individual patient, rather than a randomly selected member of some population with the same test results. "Bayesian statistics that combining your result with the prior gives you 99% confidence and, presto! a statistically significant publishable result! Of course not." Indeed not! Bayesian conclusions are only as strong as the priors used, if you could show the priors were unreasonable then you could reject the result of the test (and the paper). If you can't question the prior, you are logically forced to accept the result of the test. The good thing about the Bayesian approach is that the priors are explicitly stated. If you disagree with the use of priors on the hypothesis, you could always use a "significance test" based on Bayes factors instead, where the priors (on the hypotheses) do not appear in the analysis. "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." That is equally true of any frequentist analysis - if your information changes, your view on the truth of the hypothesis should also change, whatever form of analysis you choose. "But that calculation of P(M4|N) stands, and will forever be useful as a piece of the evidence used to assess P(N)." That is only correct if M4 is independent of M1-M3 & M5 (otherwise it is the so-called Naive Bayes approach), which in the case of climate change is rather unlikely as rising levels of atmospheric carbon dioxide are posited to be a causal factor for a great many phenomena. "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" This is incorrect, the whole point of the Bayesian formulation is that it allows your to deal rationally with the fact that you don't know something, or that you have imperfect knowledge of somthing. You choose a prior distribution that captures what you do and don't know about it and marginalise. The perfect Bayesian calculation reflects the consequences of that uncertainty. ", except for what we infer through these tests." This is incorrect, the operational priors are estimated from epidemiological studies, not just from diagnostic tests followed by biopsies. "But you don't subject patients to tests that tell 1 in 5 healthy people they have cancer" Neither a competent Bayesian nor frequentist statisticians would do so. Eric L. @19: I agree there, however given sufficient data it is similarly virtually always possible to get a statistically significant result even if the effect size is negligible, which is the flip side to the same coin. A common criticism of frequentist statistical tests is that we almost always know from prior knowledge that the null hypothesis is false from the outset. For instance with temperature trends, do we really think the trend is actually exactly zero? Anyway the differences between the two frameworks is a fascinating topic in its own right, you need a really solid understanding of both frameworks to know which tool to use for which job.

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