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Comments 107051 to 107100:

107051. Composer99 at 14:01 PM on 14 October 2010
        Newcomers, Start Here
        As one of the newbies here, might I make a suggestion (this being the introductory thread for newcomers)? It would seem to me that the blog posts on this site comprise three types: (1) The 'meat and potatoes' of the site: parsing and skeptically analysing the generic arguments posited by climate contrarians/skeptics (2) Critical analysis of specific instances of (to borrow from Ben Goldacre) 'bad science' on the part of contrarians/skeptics (e.g. blog posts on WattsUpWithThat, or by Goddard or Nova, or posts describing takedowns of Monckton) (3) New and interesting research in climate science Is there a possibility of the other two categories of post getting their own meta-posts, with some sort of permanent link on one of the menu bars?
        Response: Thanks for the suggestion. However, there's so many (2) and (3) type posts, the margins would be overflowing (besides, I have other cooler plans for the margins)
        
107052. scaddenp at 13:54 PM on 14 October 2010
        Medieval Warm Period was warmer
        Heidi, all proxies have two things that make useful. 1/ Something is dependent on temperature in a known way 2/ Some way of dating the proxy. Now ALL proxies have problems. A temperature reconstruction is no good without estimates of uncertainty which are large. Problems with both the temperature relationship and dating dog both. However, that does not mean they are no use. You can test theory to see whether the proxies match within the uncertainties As to individual proxies - best to look up detail. Ice cores, tree rings, stalagmites etc. have excellent time resolution. The oxygen isotope ratio in ice is an excellent thermometer so ice core is probably best we have - but only tell the temperature of places that accumulate ice. Tree rings and stalagmites are more problematic. Sediments, corals etc add in a dating problem. However, I wouldn't get carried away on paleoclimate - its skeptic fun park because of the uncertainty. AGW is founded in physics but tested against paleoclimate.
107053. Roger A. Wehage at 13:37 PM on 14 October 2010
        Do the IPCC use alarmist language?
        "That's not food for thought, its nonsense. The independent probabilities of multiple events don't add." You are absolutely correct. They don't just add or subtract or multiply or divide; they do all these plus thousands or millions of others. Try this: You have a rectangle whose length and width are each described by a normal distribution with a different mean and standard deviation. How would you describe the rectangle's area, length time width? What if opposite sides weren't parallel, and the angles were described by normal distributions with different means and standard deviations? What if the sides weren't even straight lines? What if the distributions weren't normal, but skewed or lognormal or something else? The algebra of probabilistic distributions is extremely complex and a danger in the hands of people who don't understand it or who pretend to. Extrapolating complex environmental data described by complex statistical relationships into the future is indeed a difficult process and subject to many hazards in the hands of those who don't have the prerequisite background or tools. I know enough to know that I have neither the prerequisite background nor the tools to predict the probabilistic distribution of anything more than simple statistical examples.
107054. Tom Dayton at 13:21 PM on 14 October 2010
        Do the IPCC use alarmist language?
        Roger Wehage, you will be surprised to learn that there is more to decision theory than "six sigma." Many decades more to it. There are societies, journals, academic departments, technologies, and successful commercial consultancies specializing in application of those technologies. Just type "decision theory" into your internet search engine. Specifically regarding the IPCC, you could read the relevant sections of the IPCC reports that describe how the IPCC decided on their published probability estimates. But if that's too technical, then you might be interested in a good poster that was presented at the American Geophysical Union in 2009. It was by a PhD student in philosophy, rather than by a statistician, so it is a good, comprehensible, basic, explanation. It does not seem to be online except for its abstract ("A Defence of the AR4's Bayesian Approach to Quantifying Uncertainty"), but perhaps if you contact the author he will send you the contents.
107055. kdkd at 13:15 PM on 14 October 2010
        New temperature reconstruction vindicates ...
        muoncounter #157 You can demonstrate the effect sizes needed for statistical significance as I explained in this post. A further thing of note, is that if you're doing short-series correlations, and the value of R2 varies wildly depending on the start and end points within the set of data that you're interested in, then you're doing something wrong, and need more context or alternative statistical methods. In Peter Hogarth's (#156) instance, you'd want to control for the effect of ENSO in some way, and then measure the trend.
107056. Roger A. Wehage at 13:09 PM on 14 October 2010
        Do the IPCC use alarmist language?
        "Montecarlo methods are more common in complex model uncertainty estimation." I have been in the computer-based modeling and simulation business for over thirty years. I invented the acronym GIGOSIM, which stands for Garbage In, Garbage Out SIMulation. When using computer-based models to analyze highly complex, nonlinear systems whose accurate response predictions depend on many nonlinear topological relationships, parameters, and input data, it is absolutely necessary to identify and include all significant topological, parametric, and boundary data. Montecarlo methods may have some utility if a model's topological and boundary relationships are fairly well established, otherwise they could "verify" erroneous models whose output may appear to give the expected results. Nonlinear systems can do that. Yvan Dutil said, "I did used to calculate failure risk in space mission. This is not that difficult. All you need is decent estimate of the component reliability." If it is not so difficult, then why has NASA spent $Billions on it and failed? Because the space shuttle is a nightmare. A little O-ring failure here a little insulation impacting a tile there. A gas leak here a stuck valve there. I've a feeling Earth's climate is no different. Just as one can't model part of a space shuttle without knowing thousands of boundary conditions, one can't model part of Earth's environment without knowing thousands of boundary conditions. Too many scientists zoom in on one or a few critical factors while ignoring others in the name of simplifying down to manageable levels at the risk of biased or even incorrect projections. This could lead to GIGOSM, and let the reader beware.
        Moderator Response: If you want to discuss the specific topic of climate models' validity, please do so on the thread Models are unreliable.
107057. muoncounter at 12:52 PM on 14 October 2010
        Do the IPCC use alarmist language?
        #7: "more than one billion parts. What is the probability that the shuttle will fail if each part has a probability of 1 in a million of failing?" That's not food for thought, its nonsense. The independent probabilities of multiple events don't add. But we should ask: What is the really alarmist language? The 'very likelys' or 'most likelys' described above? Compare those mild-mannered phrases to 'scam', 'fraud', 'big lie', 'propaganda', 'deceitful', 'snowmageddon', and the like.
107058. barry1487 at 12:30 PM on 14 October 2010
        Do the IPCC use alarmist language?
        

        It's OK to be alarmed when facing extinction

        What does that have to do with climate change or airplanes?
107059. Yvan Dutil at 12:21 PM on 14 October 2010
        Do the IPCC use alarmist language?
        In one of my many former life, I did used to calculate failure risk in space mission. This is not that difficult. All you need is decent estimate of the component reliability. Those have to be crossverified when possible. As for probability assesment, IPCC language has been used to translate scientific uncertainties in layman language. In my mind, this is a combinaison of reported uncertainties (combined pdf) and expert assesment. This is not different of what you see in other field like risk management where similar approach is used.
107060. Heidi at 12:20 PM on 14 October 2010
        Medieval Warm Period was warmer
        So, what I get told often is: How does anyone really know the temperatures during the Middle Ages? There's no data back beyond 30 or 50 years. Scientists are just guessing. It's mumbo jumbo because there's a lot of money in research on climate change. It's a fad. You say it's based on ice core samples, tree rings, coral reefs, and other proxy measurements but how do those work to generate believable information? How can an ice core, for example, tell you the temperature of the earth a thousand years ago? I hope you aren't pulling your hair out right now. It's basic but I get challenged all the time on this in conversations with bright, well-informed, educated people who don't believe in climate change because they don't believe the data. It would be great to have a non-super-technical explanation of why scientists know we are experiencing something truly unique climate-wise; an explanation of the way you measure and why it's accurate. Thanks!
107061. scaddenp at 12:14 PM on 14 October 2010
        Do the IPCC use alarmist language?
        Robert - You could read the papers on estimating uncertainty and probability in various aspects of climate instead of making unsubstantiated suggestions about dart boards. eg Annan and Hargreaves. Montecarlo methods are more common in complex model uncertainty estimation.
107062. Roger A. Wehage at 11:57 AM on 14 October 2010
        Do the IPCC use alarmist language?
        I suppose IPCC have not heard of six sigma. The area under one tail of the normal curve 6 sigma out is approximately 10^-9, which corresponds to a probability of 1 in a billion. The area under one tail of the normal curve 4.5 sigma out is approximately 10^-6, which corresponds to a probability of about 1 in a million. Manufacturing strives for a failure rate of less than 1 in a million. Now some food for thought. The space shuttle has more than one billion parts. What is the probability that the shuttle will fail if each part has a probability of 1 in a million of failing? So where would IPCC come up with their numbers? A dart board? Or let's see; nine papers out of ten said that a doubling of atmospheric CO2 will warm the planet by more than 1.5 degrees, so the probability is 9 out of 10 that it will be more than 1.5 degrees. So which would be more useful to the reader, 9 out of 10, where the numbers were pulled from their butts, or "very" and (un)"likely", which were also pulled from their butts and mean nothing. I claim that the second option is closer to reflecting what the IPCC really knows about their probabilities. $Billions have been spent on computing the space shuttle's probability of failure and probability of catastrophic failure. Here is a little discussion. How well did they do? Miserably. Probably about the same as the old Indian who held up a piece of rope to predict the weather. If it's wet it's raining and if it wiggles the wind is blowing. Probability is all relative. I wouldn't rely on any of their "Three different approaches are used to describe uncertainties..." Astronauts are reckless and know they have a much greater probability of blowing up than passengers in James' airplane. But I'm not, and I won't get on board, especially if he is relying on other sources for his information. How many important inputs were "estimated" (scientific wild ass guesses or SWAGs?) or ignored or left out for simplicity or cost reduction or just overlooked? Back in my college days I computed numbers to three digits with my trusty old Post slide rule. Today, students compute answers to sixteen or more digits and write them all down. Which answer is more accurate? Precise? My advice is, read the information and study the charts and graphs. If something is "very important" to you, then don't take their word for it, but dig deeper into the subject.
107063. beam me up scotty at 11:48 AM on 14 October 2010
        Do the IPCC use alarmist language?
        It's OK to be alarmed when facing extinction
107064. muoncounter at 10:55 AM on 14 October 2010
        New temperature reconstruction vindicates ...
        #156: "to get close to a meaningful trend we would want to calculate over a minimum period equivalent to several of the maximum length ENSO cycles" Peter, I think that statement is the key take-away here. Whenever trends are calculated using long enough data sets, we see 'statistically significant warming.' When the 2,3,5,10 year trends are calculated, you can get whatever you want, depending on how you've picked the years. To me, that's the working definition of 'statistical significance.'
107065. chris1204 at 10:45 AM on 14 October 2010
        Explaining Arctic sea ice loss
        Philippe @ 22: I think you're being a little hard on RSVP ("No one can deny Arctic ice thinning or the opening of "northwest" passages. (...and I assume these still close up in winter)... You mean, you don't really know that? While I don't possess mind reading powers, I suspect RSVP was being ironical. Whether his irony was misplaced is another issue.
107066. Byron Smith at 10:08 AM on 14 October 2010
        Global warming impact on tropical species greater than expected
        so too does it's need for food Typo: it's --> its
107067. dana1981 at 10:00 AM on 14 October 2010
        Do the IPCC use alarmist language?
        Very nice explanation, James. Well done.
107068. Peter Hogarth at 09:58 AM on 14 October 2010
        New temperature reconstruction vindicates ...
        muoncounter at 03:43 AM on 14 October, 2010 I think protestant is saying that calculating the mean trend over a period between two ENSO peaks is valid? I checked the trend (it looks similar), but the premise is incorrect, and it is still cherrypicking. From a signal analysis point of view to get close to a meaningful trend we would want to calculate over a minimum period equivalent to several of the maximum length ENSO cycles, - if ENSO has a strong influence (which it does). This would be closer to 20 years than 10. We would normally try to take a trend through extreme excursions like the 1998 peak. To take this peak as a starting point for a 10 year trend is as wrong headed as using it as an end point for the previous decade. Both trend results would be unduly biased in opposite directions. A running decadal average (red below) would be better at extracting underlying trends with minimised ENSO influence, but as this clearly shows the underlying rising trend few deniers would recommend this methodology. Back to the post, the rather crude reconstruction here (using most of Ljungqvist 2009 data) seems suspect in some areas compared to Ljungqvist 2010. If so, by association, so is Loehle, as the methodology is similar (but he uses less proxies).
107069. Joe Blog at 09:33 AM on 14 October 2010
        The sun upside down
        Thank you Riccardo for the links(the Haigh one didnt work for me, but im pretty sure ive read that one any way) Just to me, the stratospheric tropospheric interactions in relation to the solar cycle, seem a more viable hypothesis than say the cosmic ray hypothesis, as far as climate variability go(i could be wrong o course). Bearing in mind we are weighting the stratospheric response with co2 cooling up there, and in the past with CFC depletion of O3... An interesting area of inquiry anyway as far as solar effects on climate variability, through dynamical responses to variable UV.
107070. Doug Bostrom at 08:50 AM on 14 October 2010
        Do the IPCC use alarmist language?
        Amazing that Skeptical Science's James Wight betters the Royal Society when it comes to dealing with this. In the mind of the public one of the central problems in dealing with this affair is thinking about risk. While the RS failed to lend sufficient emphasis to explanations of probability and hence risk in their most recent attempt at a statement, here's a useful elaboration of the IPCC's own acknowledgments. Thanks, James. On a broader note, a lot of skeptic infection depends on people never actually looking at the IPCC report. James linked it above, here it is again just in case somebody missed it. Speaking of alarmists, perhaps it ought to go in the "incoherence thread" but reading this I was immediately struck by how frequently skeptics refer to our lamented warming as quite possibly helping us avert another Ice Age. I've never seen these claims bracketed with language on uncertainty...
107071. Albatross at 08:13 AM on 14 October 2010
        Do the IPCC use alarmist language?
        James, Interesting post. Just to place the cost of these natural disasters in context. Putting the tragic and painful loss of life aside for a second, the cost of the floods in Pakistan is estimated at almost 10 billion dollars (World Bank). It is also noteworthy that the IPCC in AR4 (their most recent report released in 2007) underestimated the loss of Arctic sea ice and increase in global sea levels. GHG emissions are currently running along the upper edge of their uncertainty range. So much for them being "alarmist".... Re the plane analogy. I personally think that we have all purchased our tickets and are barreling sown the runway knowing that there is something wrong with one of the engines. Yet, the 'skeptics' on the plane are arguing about what could be making that disturbing noise, or what natural cause might be responsible for the smoke spewing from engine number 2. Meanwhile, the pilots (and flight attendants) are taking action to mitigate the damage and avert disaster. Not I perfect analogy I know, but I'm in a rush ;)
107072. kdkd at 08:11 AM on 14 October 2010
        Carbon Dioxide - Everyone's Favorite Pollutant
        BP #183 You've done nothing to demonstrate that your position is not absurd on this issue. The more time goes on the less value your posts seem to have here, apart from exposing your sceptic position as politically motivated, not based on evidence and subject to an awful lot of confirmation bias. But even then, the more scientific stuff you've been doing lately is awfully shallow too.
107073. Rob Honeycutt at 07:55 AM on 14 October 2010
        Do the IPCC use alarmist language?
        Not to nitpick but with over 50,000 commercial airline flights per day I think the IPCC would more likely rate the chances of your plane crashing as “exceptionally unlikely.” Other than that, great post! :-)
107074. Alexandre at 07:54 AM on 14 October 2010
        Do the IPCC use alarmist language?
        ...and, on top of that, observations show the reality has been at least as dire as IPCC projections. Hardly a sign of "alarmism".
107075. Albatross at 05:24 AM on 14 October 2010
        Carbon Dioxide - Everyone's Favorite Pollutant
        BP@186, First, you owe people an answer to my question about your position on Goddard cherry-picking global SL data. Second, you are really scraping the barrel with your reference to salt. One does not have to consume even close to a pound of salt in order for it to be harmful. For this very reason, physicians, agencies and governments around the world regulate the amount of salt present in prepared foods. For example, read the position of the FDA here. Similarly, we need to regulate the emissions of CO2 to keep it at safe levels. In order to do so, the EPA is required to classify CO2 as a pollutant. The "skeptics" have had ample opportunity to present their case, the EPA patiently and thoroughly addressed each and every one of their concerns. They failed, just as you and your fellow "skeptics" are failing to make a coherent and compelling argument now.
107076. Charlie A at 04:56 AM on 14 October 2010
        Explaining Arctic sea ice loss
        michael sweet at 04:28 AM on 14 October, 2010: "The NSIDC summer summary has links to the two circumnavagations at the bottom." Thanks! I've added those two to my arctic bookmarks.
107077. muoncounter at 04:39 AM on 14 October 2010
        Explaining Arctic sea ice loss
        #27: "unaware of the yachts making it through" Try searching here for shipping news. This year’s retreat from a winter maximum of about 15 million square kilometres to a September coverage area of just five million square kilometres also means that the four greatest melts since satellite measurements began in the late 1970s have occurred in the past four years. ... Canada and the four other Arctic Ocean coastal nations — Russia, the U.S., Denmark and Norway — have pledged to co-operate in creating new search-and-rescue and environmental protection regimes to manage increased shipping, tourism and economic development in the melting Arctic.
107078. JMurphy at 04:37 AM on 14 October 2010
        Explaining Arctic sea ice loss
        Wikipedia is a good place to start for anyone wanting to know about passages through the Arctic.
107079. michael sweet at 04:28 AM on 14 October 2010
        Explaining Arctic sea ice loss
        Charlie, This cruising world article describes the 2009 year. In the article they said 11 yachts made it through (all the yachts that attempted that year). The yacht in the article went through early and later it was more open. No-one was described as needing assistance, although I would not be very surprised if someone did need assistance. Cruising World likes to be cutting edge on sailing so this fits their style. The ice was gone for so long this year that everyone would have made it for sure. The NSIDC summer summary has links to the two circumnavagations at the bottom.
107080. archiesteel at 04:26 AM on 14 October 2010
        Carbon Dioxide - Everyone's Favorite Pollutant
        @BP: I'm sure if we were to pour gigatons of NaCl in the environment it would have a deleterious effect on public health. "Government is seldom wiser than the people" Do you have empirical value to support this assertion?
107081. Bibliovermis at 03:59 AM on 14 October 2010
        Carbon Dioxide - Everyone's Favorite Pollutant
        BP, you are still stuck on acute ("real pollutants") vs chronic, except when it could make your point seem reasonable by pointing to chronic issues. For instance, plants need sulfur just as much as they need CO2 but you admit that sulfur, which is a chronic issue, can be a pollutant.

        although non-toxic

        Everything is non-toxic below a threshold value. I have to disagree that a policy of punitive, redistributive taxation is better than ameliorating the issue.

        Government is seldom wiser than the people

        The government is the people. Please spare us at this site from your ideological rants, including Animal Farm references. Rather than rambling about natural sources & breathing (OMG, gas masks!), try sticking to the topic of net anthropogenic emissions. The sophistry of "no qualitative difference exists between the CO2 from natural emissions and anthropogenic emissions" also does not further the discussion. Do volcanoes emit more CO2 than humans? (argument #59) Does breathing contribute to CO2 buildup in the atmosphere? (argument #105) Declaring that the science "is not settled enough" does not cause the science that is presented to you to disappear. The person who dismisses the accumulated scientific knowledge in favor of a political decision is the one politicizing an issue.
107082. Berényi Péter at 03:49 AM on 14 October 2010
        Carbon Dioxide - Everyone's Favorite Pollutant
        #185 archiesteel at 02:11 AM on 14 October, 2010 CO2 *is* toxic, though not at the concentrations we're talking about That's the point. Table salt is also toxic. Just try to consume a pound of it. Meets the legal criteria to be a pollutant, therefore it's high time to reintroduce a salt tax.
107083. Charlie A at 03:46 AM on 14 October 2010
        Explaining Arctic sea ice loss
        michael sweet at 18:47 PM on 13 October, 2010 said "For every year since 2007 unreinforced yachts have made the North West passage in less than a month..... This summer two yachts went entirely around the arctic ice, passing through both the North West and the North East passages. No icebreakers went with them." Do you have any links to info on this ? I was unaware of the yachts making it through the NW passage every year since 2007. I have seen some reports of yachts that attempted it and had to be rescued by icebreakers.
107084. muoncounter at 03:43 AM on 14 October 2010
        New temperature reconstruction vindicates ...
        #152: "you need to draw the lines from CREST-TO-CREST, on ENSO-neutral intervals. 1998 to 2010 is one of those intervals," I don't understand that strategy. Crests are, by definition, noise from short term phenomena. Connecting the dots from 1998's crest to 2009's crest is just as arbitrary as connecting the dots from 1993's trough to 2007's trough. The conclusion that 'there's no statistically significant warming 1998-2010' is to use two and only two data points. How is that not cherrypicking?
107085. Albatross at 03:39 AM on 14 October 2010
        Explaining Arctic sea ice loss
        Hi Doug, I do believe you re Miller et al. :o) I understand that writing these posts is probably significantly more difficult and time consuming than people expect, and that some difficult decisions need to me made along the way. It seems that some posters here are not comprehending the content of your post. All this talk about "natural cycles" when your last sentence reads: "In sum, although natural factors have always influenced the state of Arctic sea ice, research strongly suggests that today's decline is driven by the novel influence of anthropogenic C02 we've added to the atmosphere and thus is unique in Earth's history." "Skeptics" need to understand that sometimes in science the evidence is so comprehensive, so compelling, so robust that strong words are warranted/justified. Also, it seems things are indeed "going pear-shaped", so sticking our heads in the sand (or trying to convince ourselves that the ice loss is mostly "natural") is not going to help address or avoid dealing with the situation. Moreover, such actions are neither constructive nor responsible.
107086. Doug Bostrom at 03:24 AM on 14 October 2010
        Explaining Arctic sea ice loss
        Albatross, you probably won't believe it but I actually had that Miller paper listed along w/Polyak, dropped it because I thought it insufficiently ice-specific. It's a deliciously rich review of proxies, an education in itself and I suppose in retrospect should have left it in as a resource for readers; next time I'll listen better to my intuition. Temperature and precipitation history of the Arctic (full text, pdf) Looking at Polyak, I agree I've probably understated the conclusions. I suppose I've become too sensitive to skeptic susceptibility to going hysterical over strongly worded hints that things are going pear-shaped.
107087. Albatross at 02:41 AM on 14 October 2010
        Explaining Arctic sea ice loss
        Doug, good post. However, some humble suggestions. Maybe more focus needs to be placed on a) Polyak and b) Polar amplification. The following conclusion by Polyak et al., is in my opinion very striking: "The current reduction in Arctic ice cover started in the late 19th century,consistent with the rapidly warming climate,and became very pronounced over the last three decades.This ice loss appears to be unmatched over at least the last few thousand years and unexplainable by any of the known natural variabilities." Using cycles (internal climate variability) to explain long- term trends in Arctic ice does not work, unless one can demonstrate that the cycles themselves have become locked in a particular phase, or if one particular phase of the cycle has become favoured. But then, how does one then know for sure that the change in the cycle's behaviour is purely natural of affected by changes in the circulation brought about by AGW? The events unfolding in the Arctic are consistent with those predicted to occur in association with AGW by Hansen (1981) and Manabe et al. (1992). You might be interested in a new paper out by Miller et al. (2010, Quaternary Sci. Rev., same issue as the Polyak et al. paper) which finds that Arctic amplification on Quaternary time scales consistently exceeds the N. Hemisphere average by a factor of 3-4. Right now that factor is about 2. By forcing the biosphere into a net positive energy imbalance, we humans have set in motion a sequence of events in the Arctic which has led to the manifestation of polar amplification. Going by the work of Miller et al. (2010), the warming (and attendant reductions in ice) in the Arctic will likely continue to accelerate in coming decades on account of polar amplification.
107088. Ned at 02:36 AM on 14 October 2010
        New temperature reconstruction vindicates ...
        protestant writes: The Lundgqvist data ends on 1999 so therefore you need to ONLY add the temperature increase since then (with 10yr smoothing). Your "method" to add the thermometer data is HIGHLY suspicious, since the NH hasnt warmed since 1990 any more than 0.4 degrees. Best way would be to add the 2000-2009 decadal mean as a spot to the end and THATS IT. I think you're reading deceptive intent where none exists. I wanted to compare a number of different reconstructions including that of Loehle which isn't calibrated to anything else and ends in 1935. In order to do that, it's necessary to somehow recenter the various reconstructions. In Figure 2 I did this based on the period of overlap among the reconstructions, while in Figure 3 I did this by matching each one as closely as possible to the instrumental record during their period of overlap with the instrumental record. One can argue about which is better, but they're both up there. Comparing proxy-based reconstructions to the instrumental record is inherently problematic. Yes, the temporal resolution is different, and some proxies show a well known divergence from actual temperatures in recent decades. There's also the question of which instrumental record to use as a comparison (land vs land/ocean, NH vs global). Faced with those problems, one can either not compare to the instrumental record (and thus draw no conclusions about how past temperatures compare to the present) or one can try to match the proxy and instrumental records as closely as possible during their period of overlap. This is what I do in Figure 3. I understand Ljungqvist's comment that you cite ("a very cautious interpretation of the level of warmth since AD 1990 compared to that of the peak warming during the Roman Warm Period and the Medieval Warm Period is strongly suggested") and have no problem with that. However, the key point of my post is to assess the degree to which Ljungqvist "vindicates" Loehle (2008) vs "vindicating" other reconstructions. Loehle's reconstruction is supposed to be a global reconstruction, yet it shows a greater amplitude for NH-centric episodes than actual NH reconstructions (Ljungqvist, Mann, Moberg). To me, that suggests that insofar as Ljungqvist 2010 "vindicates" anyone, it's a much better match to Mann or Moberg than Loehle.
107089. muoncounter at 02:35 AM on 14 October 2010
        Explaining Arctic sea ice loss
        #20: "winter average temp has increased, but the summer temps have been stable according to the satellite data." TIS, Prior discussion here may save you some effort. See this prior thread and this one as well. A search will bring up others; this subject gets a lot of attention (as well it should). Minimum (September) ice extent anomalies are increasing in magnitude more rapidly than maximum (March) anomalies. The melt season is also getting longer. Prior discussion noted that 'new ice' melts faster than 'old ice' and that ice thickness continues to decrease. The combination of longer melt season, rising temperatures and a higher percentage of new ice to old ice makes increasingly rapid melt inevitable, with or without AMO.
107090. Philippe Chantreau at 02:33 AM on 14 October 2010
        Explaining Arctic sea ice loss
        RSVP: "No one can deny Artic ice thinning or the opening of "northwest" passages. (...and I assume these still close up in winter.)" You mean, you don't really know that? And you couldn't bother doing the extremely basic fact-check before piping a comment? What is the point of commenting on a subject of which you spontaneously confess that you are so ill-informed? This: "land" and "water", quotations marks yours. Why the quotation marks? Are you trying to suggest that they are not really water or land? And this: "the Artic has a built in predisposition to melting anyway due to its lower elevations." The Arctic is an ocean. Lower elevations? I don't know what you're trying to say there.
107091. Daniel J. Andrews at 02:33 AM on 14 October 2010
        Billions of Blow Dryers: Some Missing Heat Returns to Haunt Us
        I know it is officially off-topic, but things seem quieter here now. Just wanted to offer a very heartfelt thank you, Doug, for your salute to oceanographers and others who have to undergo tedious time-consuming and sometimes dangerous lengths just to grab a smidgen of data that amounts to a few brief paragraphs in a journal article. Thank you for recognizing what they, and others, have to undergo to collect that data. We lost four people in a helicopter crash a few years ago, and this past summer two others, whom I didn't know, crashed while working in the far north around Hudson Bay. Sometimes I think we scientists need to award medals, akin to the military medals, to our colleagues in any discipline who have died while doing their jobs.
107092. JMurphy at 02:30 AM on 14 October 2010
        The value of coherence in science
        I think there is a very good example of 'so-called skeptic' incoherence at the moment, over the Wegman Report accusations. Previously we were told that the report was a serious, peer-reviewed scientific study headed by a serious statistician whose views on the 'hockey-stick' could be boiled down into the succint saying : "Method Wrong + Answer Correct = Bad Science". Now, however, we are being asked to believe that the report shouldn't be held up to as high a standard as peer-reviewed scientific studies (it was only a report to Congress that had to be made as intelligible as possible to the layman, for heaven's sake !); that Wegman can't be held responsible for everything in the report, especially the stuff he didn't know anything about (although you wouldn't have known that at the time); and that, anyway, the statistical bits are the most important bits and it doesn't matter if the rest of it is copied from elsewhere, i.e. "(Some) Method(s) Wrong + Answer Correct (as believed by all 'so-called skeptics') = (Not really, totally) Bad Science (especially the bits that 'so-called skeptics' need to accept as being true)". Try and rationalise that about-turn...
107093. michael sweet at 02:28 AM on 14 October 2010
        Explaining Arctic sea ice loss
        TIS, There is a huge amount of data on the North West passage, you have just not looked for it. There are people who LIVE in the NW passage who actually write down each year what the ice is like. They have lived there for over 100 years so the record goes back a long way. Ships have a long tradition of writing down the ice concentrations they meet and that takes the record back into the 1700's, although not as complete the further back you go. Arctic explorers spent decades trying to get through the North West passage, starting with Cook in 1776, of course they kept records. Arctic temperatures over ice have stayed the same since the melting ice controls the temperature. The sign of AGW is more melting. NSIDC uses a chart of temperature at 1000 meters to see actual temperature rise. WUWT has a trick graph of surface temperature north of 80 degrees they use to fool people who don't pay attention.
107094. CBDunkerson at 02:23 AM on 14 October 2010
        Waste heat vs greenhouse warming
        Over here RSVP suggested that waste heat from Northern hemisphere industrialized nations was responsible for the decline of Arctic sea ice. The 'evidence' for this is that Antarctica is not melting at the same rate as the Arctic sea ice and there are fewer industrial nations in the southern hemisphere. If this concept of 'geographically localized waste heat' were not completely ludicrous (hint: it is) we would of course see the greatest temperature increases at the most heavily industrialized sites. Thus, the area in and around New York City should show tremendous temperature anomalies with decreasing amounts radiating out from there and other industrial centers. The Arctic ocean, having virtually no industry, should of course only show comparatively minor warming from those distant industrial sites. This, of course, is not at all the case. The Arctic has warmed far more than New York City or any other industrial center. Because it has nothing to do with waste heat within a geographic region.
107095. archiesteel at 02:18 AM on 14 October 2010
        It's the sun
        @Ken: why would I leave? I enjoy seeing you squirm around while trying to defend illogical points. Your arrogance only compounds the farcical nature of your arguments. "Where the Solar irradiance forcing crosses the axis is where TSI is neither warming or cooling the planet, in the absence of other forcings. Any disagreement with that?" TSI is warming the planet. How could radiated energy cause the planet to cool? Again, you're confusing absolute values with deltas. You have failed to successfully argue your point. You can stick around if you want, but you'll only make yourself look more foolish. Your choice.
107096. archiesteel at 02:11 AM on 14 October 2010
        Carbon Dioxide - Everyone's Favorite Pollutant
        @BP: "If CO2, although non-toxic, is supposed to be harmful in some intricate way, putting a price tag on emissions is a possibility." CO2 *is* toxic, though not at the concentrations we're talking about. CO2 meets the legal criteria to be a pollutant.
107097. The Inconvenient Skeptic at 01:49 AM on 14 October 2010
        Explaining Arctic sea ice loss
        Robert, As I stated I do not believe the AMO is the only factor, but there is not sufficient information of the impact on the northwest passage from the last warm AMO to know the full impact. What was the status from 1945-1955? All that can be verified is that 1944 was a low ice year. As the AMO stayed strong after that it is not possible to say what the status was. There is simply not sufficient data available on the state of the northwest passage from before to state if this is unprecedented or not. I will put something together on the Arctic temperatures. The winter average temp has increased, but the summer temps have been stable according to the satellite data. I will have it up by the end of the week, probably Friday. John
107098. Doug Bostrom at 01:45 AM on 14 October 2010
        Explaining Arctic sea ice loss
        As always, a good general approach is to first read the research, then dispute the cause based on an informed perspective.
107099. RSVP at 01:31 AM on 14 October 2010
        Explaining Arctic sea ice loss
        kdkd "The antarctic ice sheet many many times bigger than greenland. " Adelady "The Antarctic is much more exposed to cold being entirely surrounded by the chilly Southern Oceans." Ned "The distribution of CO2 is more or less uniform" No one can deny Artic ice thinning or the opening of "northwest" passages. (...and I assume these still close up in winter.) What can still be disputed however is the cause. In a bygone thread, the major reason forwarded to discount industrial waste heat as a significant climate forcer is how it pales numerically with the total radiative effects of incremental GHG over the entire Earth surface. What happens however when the comparison is made between the total heat output of industrial nations crouded above the 45 parallel the supposed incremental radiative forcing of GHG in that same restricted area. In addition, when comparing Artic and Antartic regions geographically, it is clear that one is "water" and the other "land". This apparently affects ice cumulation regardless of global temperatures (i.e. there never was 4000 feet of ice at the north pole), which means that the Artic has a built in predisposition to melting anyway due to its lower elevations. Since it doesnt take "much" to accomplish this, and waste heat is a "drop in the bucket" in the scheme of things, this may have more to do with what is really going on than is suspected.
        Moderator Response: Given its easily quantified irrelevance in comparison to natural variability, we'll do better to continue sequestering further discussion of waste heat in the existing "Waste heat vs greenhouse warming" thread.
107100. protestant at 01:31 AM on 14 October 2010
        New temperature reconstruction vindicates ...
        Here is actually a screenshot from the paper, a more honest apples-to-oranges comparison: The modern maximum clearly fits to the MWP and RWP margins. And even considering the fact that the graph uses data up to 1999 there is actually little or no need for such a comparison. Try calculating 2000-2009 minus 1990-1999 and add the result on the papers 1990 decaedal mean. Neds plots are really exaggerated and falsely interpreted.

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