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Comments 87151 to 87200:

87151. dhogaza at 03:50 AM on 1 May 2011
       Medieval project gone wrong
       

       GP mentioned Mann, so it seems more toward that particular individual,

       Mann doesn't generate his own dendro proxy series. Yes, Mann's McI's favorite target, but Briffa (the leading paleo climatology dendro guy) isn't far behind. Hoskibui:

       wether or not it works I think is irrelevent of this post - but by the way, with or without the dendrocronology the new hockey stick works (I can make a post about that if you want :)

       True, letting GP derail the thread through a one sentence cherry pick of a quote from a single paper distracts from your post, and of course you're right that there are more hockey sticks than we know what to do with ...
87152. muoncounter at 03:48 AM on 1 May 2011
       Cosmic ray contribution to global warming negligible
       Eric#53: "the earth's magnetic field has slight seasonality" No. That seasonal variation in your reference is the external magnetic field (solar or IMF), not the earth's field. The entire GCR/clouds idea is about IMF variations.
87153. Hoskibui at 02:23 AM on 1 May 2011
       Medieval project gone wrong
       Hi, thank you all for your responses. I think that most questions have been dealt with - questions of dendrocronology and wether or not it works I think is irrelevent of this post - but by the way, with or without the dendrocronology the new hockey stick works (I can make a post about that if you want :) With the help of google translator and many good people of the Skeptical Science I think the point of the post comes a cross - thank you.
87154. Bob Lacatena at 02:12 AM on 1 May 2011
       Clouds provide negative feedback
       106, RW1,

       I addressed this already HERE.

       Really? You call that "addressed?" This was what you said:

       Look, I can only deal with one thing at a time.

       So, for the sixth time you've dodged the question, as well as my other points. You made the following statement:

       I do not see where the issues I've raised has been addressed or answered.

       I pointed out:

       That's because you ignore the statements that do address them.

       I then proceeded to itemize where and how the issues you've raised have been addressed and answered, and I took you to task to yourself address the discrepancies. And you ignored them. Instead your response now is basically that you already have addressed them (you haven't), and that you don't have to... because justifying your personal theories about net cloud feedbacks would be off topic on a thread about cloud feedbacks (although that didn't stop 50 meandering posts about Trenberth's energy budget diagram when you thought that in some way buttressed your personal theories).
87155. Albatross at 02:03 AM on 1 May 2011
       Lindzen Illusion #2: Lindzen vs. Hansen - the Sleek Veneer of the 1980s
       Mdenison @39, Please read my post @40. There is a very easy way for Lindzen to clarify this and settle this matter-- and that is for him to actually step up to the plate and produce an AOGCM of his own, and generate his own global temperature chronology. He has not and will not. Instead he chooses to play this game of nit picking, being ambiguous, and obfuscating. How people can defend that is completely beyond me. It is very clear, his estimates of a climate sensitivity of <1 K for doubling CO2 is horribly wrong, that much has been obvious for decades now, and is only going to continue to diverge further from reality.
87156. Philippe Chantreau at 01:59 AM on 1 May 2011
       Medieval project gone wrong
       I think you're pushing it Dhogaza. GP mentioned Mann, so it seems more toward that particular individual, who has gathered the irk of so-called skeptics, thanks to Steve McIntyre. It seem that McIntyre has somehow made things more personal with Mann than anybody else, as if he was the only one doing reconstructions. Then, in true Rush Limbaugh or Beck fashion, he has managed to instill anger agaiinst Mann's person among crowds who barely understand the subject. As to what McIntyre is ready to do to try to discredit Mann, this gives a notion. It is painfully obvious to anyone really paying attention that Mann is far more trustworthy than the charlatans (Trenberth' word) attacking his work and his person.
87157. Albatross at 01:58 AM on 1 May 2011
       Lindzen Illusion #2: Lindzen vs. Hansen - the Sleek Veneer of the 1980s
       This post clearly illustrates that global surface air temperature (SAT) chronology (as predicted using a climate sensitivity of + 3 K and the observed CO2) forcing is tracking very well with observations. In contrast, we have Lindzen, a complete outlier, with estimates of global surface air temperatures based on his arguments shown to, even now, be in negative territory (and would not even feature in the graph shown @35. I find it incredibly telling that Lindzen and his fellow contrarians have not ventured to produce long-term temperature predictions of global SATs in the reputable peer-reviewed scientific literature, but instead rather choose to adopt the rather cowardly and wholly unproductive tact of nit-picking others hard work and sincere efforts to advance the science. I'm seriously beginning to think that Lindzen is not a self-styled maverick or contrarian or "skeptic", but at this point is in fact in deep denial about what is unfolding before his very eyes. His reticence to concede error, to change his position is the very antithesis of good science, and for this reason the annals of scientific history will not paint a flattering picture of him, despite all his accolades. d82, neat graphs!
87158. mdenison at 01:37 AM on 1 May 2011
       Lindzen Illusion #2: Lindzen vs. Hansen - the Sleek Veneer of the 1980s
       Dana @22 I think you misinterpret Lindzen because the model you use to produce a Lindzen prediction is based on random noise and a small bias of 0.1C per century to allow for greenhouse gas warming. Lindzen's 1989 comments suggest he believes that there is a heat source (the ocean) that allows for more warming than just 0.1C and that this produces the long term temperature changes observed. You could possibly model this with low frequency noise. Not to model a heat source (or sink) it is to misrepresent Lindzen's position. So far as I can tell in 1989 Lindzen could mainly see noise. He did not have a model that could explain past events nor make predictions; so he made none. The main difference between Lindzen and Hansen is that Hansen had a model with cause and effect that could be tested and make predictions, Lindzen had none.
       Response:

       [dana1981] No, I strongly disagree.  Lindzen clearly said the surface warming was only 0.1 +/- 0.3°C.  Noise does not cause long-term trends, and I represented the effects of the oceans in the random noise.

87159. daisym at 01:29 AM on 1 May 2011
       Lindzen Illusion #2: Lindzen vs. Hansen - the Sleek Veneer of the 1980s
       dana1981; Thanks for this excellent analysis. I would love for Lindzen to leave a comment!
87160. RW1 at 01:21 AM on 1 May 2011
       Clouds provide negative feedback
       Sphaerica (RE: 159) "1. Your theory is inconsistent with all of the lines of evidence which point to a climate sensitivity of 3˚C or greater. You have seen this presented to you now at least 6 times, and you keep dodging it. How does your theory account for this? Until you answer that question, your theory fails." I addressed this already HERE. To delve into all those things here would be off topic. Moreover, it is absurd to think that I (or anyone else) is obligated to explain each line of evidence they present in the context of every other line of evidence in the whole subject of climate science.
87161. dhogaza at 00:35 AM on 1 May 2011
       Medieval project gone wrong
       GP:

       I think this implies that dendochronology is affected by more than a single variable.

       To add to the piling on, if dendochronologists trying to do paleoclimate reconstructions weren't aware of this mind-numbingly obvious fact, they wouldn't put so much effort into finding areas where there are long sequences available that *aren't* mostly impacted by spring precipitation. In particular, this is why all the tree ring proxies that are used are near their altitudinal or latitudinal boundaries, as the major impact on growth in such areas are summer temperatures. The bristlecones used, for instance, are those that are stunted in growth due to there only being a few short weeks where temps are warm enough for them to put down much growth. Bristlecones at lower elevations in the Great Basin look like "real trees" and don't live nearly as long as those that most people are familiar with (from them being the "oldest trees on the planet"). Those stunted, long-growing trees get as much or more precipitation than those 1000 feet lower on the slopes. April showers aren't the limiting factor for them (snow showers, typically, I might add). Ain't it grand how GP gloms on to one sentence pulled out from a paper and assumes that shoots down an entire field of scientific endeavor, simply because he disagrees with the implications of the work being done?
87162. Bob Lacatena at 00:06 AM on 1 May 2011
       Models are unreliable
       349, trunkmonkey,

       I can understand how you guys feel that if you have the physics nailed down...

       Since you obviously care about the issue, I would urge you to study until you also feel you have the physics nailed down. At that point where you have a viable understanding, you would also have a viable opinion. Until then, your entire position is based on feeling, not knowledge or reason.

       ...[feel that] the paleo stuff barely matters.

       Quite to the contrary, all of the evidence matters, and any contradictory evidence must be resolved one way, or the other. The problem is, there is no contradictory evidence. Observations, physics, models, paleoclimate of many... each of them in multiple, varied, forms... it all agrees, which is why there is talk of a consensus. But the real consensus isn't just among the scientists, but also among the data. All of the data is in agreement. The only contradictions that I've ever seen come from people simply making stuff up, or purposely misinterpreting or misrepresenting it to make it try to seem like there are contradictions. There are gaps, mind you. There are certainly things we don't know, or things we think we know but the margin for error is so wide that there is uncertainty. But for what we do know, everything fits. And we know a whole lot.
87163. mclamb6 at 23:57 PM on 30 April 2011
       Waste heat vs greenhouse warming
       Except your position is that waste heat is the source of a long term overall heating trend. If the heat transfer requires heat to move from higher to lower temperatures, there should be some place that is experiencing a long term cooling trend. What areas are experiencing a long term cooling trend? It's certainly not Phoenix.
87164. Eric (skeptic) at 23:32 PM on 30 April 2011
       Cosmic ray contribution to global warming negligible
       Muoncounter, you say "Seems to be a seasonal effect, which isn't a hallmark of GCRs." The effects of GCR on clouds could be seasonal due to differences in vertical profiles, cloud heights, etc. I would only expect slight seasonality from GCRs themselves as the earth's magnetic field has slight seasonality, e.g. http://geophysics.ou.edu/solid_earth/notes/mag_earth/earth.htm
87165. Bob Lacatena at 23:25 PM on 30 April 2011
       A Flanner in the Works for Snow and Ice
       143, Ken, In your tally, I believe you are ignoring a major component, i.e. energy absorbed by land (deprived of previous snow/ice cover). More importantly, Flanner's study covers the entire northern hemisphere, not just the Arctic circle, so this change in albedo would extend well south, and include a strong input resulting from the earlier springs and later winters that we have experienced since the onset of recent climate change. You keep restricting your estimate to 4.4% of the earth (I'm assuming this is the Arctic Circle, plus a bit), when snow and ice extends considerably farther south than that, particularly on land.
87166. skywatcher at 23:23 PM on 30 April 2011
       How climate change deniers led me to set up Skeptical Science website
       Astonishing, JMurphy. You wouldn't be suggesting, by that last quote, that Trenberth is arguing for policy to 'follow the data', rather than follow their favourite 'team'? Surely Trenberth wouldn't act like a true scientist and go where the data takes him? Ken Lambert, no scientist is a 'proponent of AGW' - they don't, as others say, follow it blindly like their local football team. If any person or group could come up with data successfully challenging the consensus, they would be lauded and celebrated, and the climate science community would celebrate being wrong about their prognosticatin for the Earth. Champagne would be cracked open in every climatology, geography, geology, physics and chemistry department in the world, and a great many people would sleep easier. Reputations are of trivial importance by comparison to an unpleasant future for all of mankind. The problem with denial, and the reason Skeptical Science is such a useful tool, is that those continuing to deny the evidence act very much like supporters of their local football club after they have lost the local derby match 3-0. We hear cries of "It was the ref's fault", or "Smith is a cheating so-and-so", "They fall over at the slightest touch to con the ref". What you never hear, of course is "The other team were better in every department". It's difficult to reason with entrenched people, especially when they do not understand that you would absolutely love for them to be proven correct.
       Moderator Response: [DB] Well-spoken, and amen!
87167. d82 at 23:09 PM on 30 April 2011
       Lindzen Illusion #2: Lindzen vs. Hansen - the Sleek Veneer of the 1980s
       Looking at the decadal averages of the temperature since 1880 and comparing them with Hansen et al. 1981, 1988 (solution B) and the prediction of 2007 looks as follows: Natural variability as defined in Hansen et al. of 1981 (hatched gray areas) looksbad. For more information start at http://www.xs4all.nl/~pduinker/Problemen/Klimaat%20Verandering/Warming/index.html
87168. JMurphy at 23:09 PM on 30 April 2011
       How climate change deniers led me to set up Skeptical Science website
       You've done it again ! ;-)
87169. JMurphy at 23:08 PM on 30 April 2011
       How climate change deniers led me to set up Skeptical Science website
       You just beat me Sphaerica but I'm glad you were able to pick up the way these terms are used too - I thought it was just me being picky ! Also, I forgot to add the following about being "a believer in greenhouse gas causation of climate change" - do we also call Richard Dawkins a 'believer' in Evolution, and Stephen Hawking a 'believer' in the Big Bang Theory ?
87170. les at 23:05 PM on 30 April 2011
       Medieval project gone wrong
       19 gc: For extra amusement, this issue is touched on, all be it in parsing, in Mr. Sinclair's latest video.
87171. Bob Lacatena at 23:03 PM on 30 April 2011
       How climate change deniers led me to set up Skeptical Science website
       36, Ken, Another example, just from your closing line:

       Sounds like a believer...

       "believer", as if it were a religious faith instead of a considered, logical conclusion, based on a lifetime of education, study, thought and hard work. These subtle little jabs, meant to prey on people's perceptions of the scientists, do not go unnoticed.
87172. JMurphy at 23:00 PM on 30 April 2011
       How climate change deniers led me to set up Skeptical Science website
       Ken Lambert, you are still unable to accept that the way you use words and terms is determined by your own innate bias. You are not the only one but it is very prevalent. To be a "proponent of AGW" is akin to being pro-AGW, as some others have used, i.e. to be for or supportive of AGW - in other words, to be glad of its existence in some way. Those who accept AGW are neither pro-AGW nor do they just believe in it. Those like Dr Trenberth who accept the facts of AGW are working hard to "track energy in the climate system" - and out of courtesy to others, I will link to the paper. You will also note that he references (the [2] in your quote) the IPCC AR4 Physical Science Basis for his statement, i.e. he has scientific fact to back up his claim. Finally, and not wishing to go any further off-topic on this thread, it is useful to bear in mind the concluding lines of Dr Trenberth's paper : A climate information system that firstly determines what is taking place and then establishes why is better able to provide a sound basis for predictions and which can answer important questions such as ‘Has global warming really slowed or not?’ Decisions are being made that depend on improved information about how and why our climate system is varying and changing, and the implications.
87173. Bob Lacatena at 22:59 PM on 30 April 2011
       How climate change deniers led me to set up Skeptical Science website
       36, Ken, I think you missed the point. No scientist is "in favor of or supports AGW." They may adhere to current climate theory, but the characterization of such adherence as "support" (as if they want it to happen), or the generalization of climate science into "AGW" or even "AGW theory" is playing games with words. This is what JMurphy was pointing out, that just a few words are subtly used to slight and denigrate climate scientists, and so to undermine the evidence they present, as if they've become a fan of a favorite team in a sport, and so will argue their own team's superiority (like any good fan) regardless of the evidence.
87174. Bob Lacatena at 22:45 PM on 30 April 2011
       Medieval project gone wrong
       19, gallopingcamel, To clarify things for people that don't bother to follow the links on dendroclimatology: 1) Scientists are well aware of the many factors that affect tree growth (and other proxies), allow for the errors that may be introduced, and take steps to reduce that error. 2) Tree rings are far from the only proxy used in any study. 3) All proxies are compared with other proxies and when possible actual observations to calibrate and validate them. 4) No proxy is perfect... all suffer from some issues... scientists are trying to infer temperatures from hundreds to thousands of years ago, so what would you expect? But when many different proxies agree, it becomes fairly compelling evidence.
87175. Ken Lambert at 22:25 PM on 30 April 2011
       How climate change deniers led me to set up Skeptical Science website
       JMurphy #22 I should not let you get way with this one either JMurphy: "You have to remember that Dr Trenberth is a proponent of AGW..." No - Trenberth does not argue in favour of or support AGW : he is a scientist whose "primary research has focused on the global energy and water cycles and how they are changing, and his work mainly involves empirical studies and quantitative diagnostic calculations. Trenberth is a primary advocate for the need to develop a climate information system that is an imperative for adaptation to climate change." Well here is the relevant quotation from the Introduction to Dr Trenberth's --"tracking the Earth's global energy - Aug09" here: Quote: "Given that global warming is unequivocally happening [2] and there has so far been a failure to outline, let alone implement, global plans to mitigate the warming, then adapting to the climate change is an imperative. We will of course adapt to climate change. The question is the extent to which the adaptation is planned and orderly with minimal disruption and loss of life, or whether it is unplanned? To plan for and cope with effects of climate change requires information on what is happening and why, whether observed changes are likely to continue or are a transient, how they affect regional climates and the possible impacts. Further, to the extent that the global community is able to reduce greenhouse gas emissions and mitigate the climate change, then information is required on how effective it is. This article addresses vital information needs to help understand climate change." endquote Extract: "Further, to the extent that the global community is able to reduce greenhouse gas emissions and mitigate the climate change..." Sounds like a believer in greenhouse gas causation of climate change to me.
87176. Ken Lambert at 21:09 PM on 30 April 2011
       A Flanner in the Works for Snow and Ice
       Oops - accidental enter - ignore #143 Thanks for your apology of sorts Tom. We can keep this on first name terms surely. Lets go to Dr Trenberth's paper "Tracking the Earth's Global Energy" Aug09 and make a generous estimate from it: Ref Table 1. These are his estimates: in Joules/year Arctic Sea Ice: 1E20 Ice Sheets: 1.4E20 (half Greenland half Antarctica) Ocean (global): 20-95E20 (average 58E20) For the Arctic estimate of NET heat absorption (incoming minus outgoing): Arctic Sea Ice: 1E20 Ice Sheets: 0.7E20 (including all Greenland loss) Ocean: 4.2% of 58E20 = 2.44E20 for all Earth area above 66N Total: 1 + 0.7 + 2.44 = 4.14E20 Joules/year This assumes that ALL the Greenland ice loss is included and the area proportion (4.2%) of the global average ocean heat absorption even though not all the ice is lost in the Arctic in summer so the average albedo for the whole planet's oceans is implied in using the 4.2% proportion. This is conservative because most of the worlds oceans are ice free and the average albedo would be lower than the Arctic which still has ice in summer. Even if we took the top end of Dr Trenberth's range for global oceans of 95E20 Joules/year, then 4.2% of that would be 3.99E20 and the sum 1 + 0.7 + 3.99 = 5.69E20 Joules/year. With the above conservative assumptions, the NET Arctic range is 4.14 - 5.69E20 Joules/year. Adding in the 4.2% proportion from the global oceans also ignores any transport of heat from elsewhere on the planet, so surely overestimates the effect of absorption Solar heat by albedo decrease due to ice loss of the Arctic surface area by itself. The above 4.14 - 5.69E20 number is still roughly half the NET 9.17E20 Joules/year you are claiming from Flanner.
87177. Tom Curtis at 20:31 PM on 30 April 2011
       Lindzen Illusion #2: Lindzen vs. Hansen - the Sleek Veneer of the 1980s
       angusmac @35, Dana clearly shows the correlation between the data the "prediction" for scenario C in figure 1. This correlation, however, is purely a consequence of Hansen using a climate sensitivity of 4.2 degrees C per doubling of CO2. Dana shows the consequences adjusting the prediction for the IPCC accepted climate sensitivity in figure 3, in which the adjusted scenario B prediction underestimates the temperature data. Of course, the scenario C prediction using a climate sensitivity of 3 would perform far worse than does the scenario B prediction.
87178. Marcus at 18:38 PM on 30 April 2011
       CO2 is plant food? If only it were so simple
       "I worked 10 years (including: for the Department of Agriculture - the U.S.) on the influence of climate on aphids - and their "enemies” (10 years I taught the students of agriculture, what you should know about: pest control - climate)." So on the basis of a *single* example, & not a very consistent one at that, you make broad generalizations-how typical of you Ark. Did you factor in the effects of raised CO2 levels as well as temperature? Many studies I've read suggest that breeding cycles of many insect pests will be enhanced by a combination of warmer weather & increased CO2-which would tend to trump your interesting, but hardly convincing, anecdotal "evidence". There is also the FACE study that shows reduced plant resistance to insect predation under eCO2 conditions. I've also read that eCO2 makes herbicides less effective-thus making invasive weeds an even bigger problem in crop management. I've already raised the implications of the results regarding the impacts of eCO2 on soil-borne pathogens. These 3 factors alone (Insect Pest numbers/plant resistance, Weed Numbers/Herbicide Efficacy & soil-borne pathogens) really don't leave your own anecdotal evidence standing up too well-& certainly makes Bubyko's position look very shaky (still, you've proven to have a habit of putting people's unfounded opinions ahead of the bulk of established science). "It is generally thought that it was mostly dry conditions in warm climates limit the positive effects of increase p.CO2 for photosynthesis - the yield of crops. But let us be careful of such conclusions." Why Ark? The two instances are completely different. Any climate change which occurred over the MWP did so over a space of several *hundred* years-& even peak temperatures were not believed to be much higher than they were around the 1970's. What this means is that crops had several hundred years to adapt to what would have been pretty modest changes in climate, whereas current crops need to adjust to climate changes in the space of little more than 100 years, as well as coping with any negative effects of rising CO2 *at the same time*. Also, its worth pointing out that famines were hardly limited to the 13th & 14th century-they also feature in many of the previous centuries, & were not limited strictly to Europe. I suggest you check your facts a bit better in future.
87179. Philippe Chantreau at 17:57 PM on 30 April 2011
       Medieval project gone wrong
       Each tree ring shows early wood and late wood. The early wood is the one more dependent on spring prescipitation. Gallopingcamel, you could have found this in a few seconds on Google. http://en.wikipedia.org/wiki/Dendroclimatology
87180. RSVP at 17:39 PM on 30 April 2011
       Waste heat vs greenhouse warming
       muoncounter 406, mclamb6 407 "How do you know that?" This is dictated by heat transfer fundamentals. Heat transfers via conduction, convection, and radiation. In all three cases it always goes from a material with a higher state of energy to a lower state of energy. All materials behave this way, so heat always migrates from a warmer place to a cooler place. This is what the word "dissipation" in the article refers to. In Phoenix Arizona, you have a daylight pulse wherein the net heat builds, yet even so, heat is constantly radiating, even during the day. This loss of heat due to radiation, is considered "cooling", because not all the heat from the Sun is accumulating. Given the respite night provides, most of the heat taken in during the previous day gets radiated out into space, and its then that cooling is most noticable. Heating from all the air conditioners running in Phoenix offsets the natural thermal equilibrium that existed in nature. It can only be warmer in Phoenix as a result of these and other human induced heat sources. And although temperatures in Phoenix might be a tad higher, this extra energy is drawn off by surrounding desert air due to thermals and cyclical wind conditions. This extra energy is not lost however and dissipates as the article states. The cumulative effect of heat generated from industry in the northern hemisphere acts like a thermal noose around the Artic. That GHG should affect the entire planet equally refers to the assumption that CO2 is in general evenly distributed throughtout the atmosphere. So to whatever extent CO2 has acted in the past as GHG (whether locally or otherwise), it should do so in like manner even as its concentration rises.
87181. angusmac at 17:06 PM on 30 April 2011
       Lindzen Illusion #2: Lindzen vs. Hansen - the Sleek Veneer of the 1980s
       Illuminating post Dana but you neglect to mention that Hansen's Scenario C actually gives the best fit to the GISS temperature data, not Scenario B. See the chart below.
       Moderator Response: [DB] Umm, no. See here for robust discussion, where you previously advanced this misunderstanding and were provided edification (please put future discussions of this there as well). Repeating a misunderstanding does not unmake it as a misunderstanding.
87182. Marcus at 17:05 PM on 30 April 2011
       CO2 is plant food? If only it were so simple
       @ Arkadiusz Semczyszak ....and, as before, you've given us *no* real evidence to back your claims. Where is the proof that famines in the 13th & 14th century were actually caused by climate? They certainly weren't caused by lower levels of CO2-which were at 280ppm throughout that entire time. I'd actually argue that a big part of any famines during that time period might have been the fact that the bulk of the rural labor force had been wiped out by The Black Death-or perhaps you hadn't ever heard of that?
87183. Tom Curtis at 15:30 PM on 30 April 2011
       Models are unreliable
       trunkmonkey @349: First, the primary long term consequence of life to the physics of Earth is that Entropy is increased by is presence by a significant degree more than it would have been in its absence. So from the physics perspective, life very much acts according to the spirit of the 2nd Law of Thermodynamics. Second, the rest of your post reads like nothing other than an example of the hubris of ignorance - the belief of a person that because they themselves do not know particularly much on a subject, therefore nobody knows much more. If this is all the argument you have to offer - the vaunting of ignorance, then you have no argument, only an unwillingness to follow the evidence.
87184. Tom Curtis at 15:19 PM on 30 April 2011
       Medieval project gone wrong
       gallopingcamel @19, trees ,like everything else, need a lot of factors in their favour to grow well. They need sufficient water, sufficient sunlight, a lack of too many boring or grazing pests, nitrogen in the soil, healthy root fungi to take in soil nutrients, and of course, sufficient warmth. (The list is not exhaustive.) Also like everything else, the thing which limits the growth rate most is the thing in least supply. Trees in the tropics rarely lack sufficient warmth, but lack of water, or too many pests can be major problems. In contrast, trees on the edge of a tree line due to latitude or altitude certainly lack warmth. In fact, they are restricted to so short growing season by lack of warmth that if, on average over a decade or so, it was any shorter, they would not grow at all. Hence the tree line. So, the factor which most determines the growth rate (and hence tree ring width) of trees varies with location, and even from tree to tree. Even the difference between being on the North slope or South slope of a hill can make a difference, due to changes in incoming sunlight. Or the difference between being on the East or West slope, which can modify precipitation and wind strength. The important thing is that these factors can be judged by carefully examining the local geography, and by checking the trees for signs of scarring that results from pests, disease or excess grazing. By doing so you can check if the primary factor is water, or disease, or temperature. Paleoclimatologists choose the trees which are suitable for what they are trying to study.
87185. gallopingcamel at 15:00 PM on 30 April 2011
       Medieval project gone wrong
       Hi y'all, While I have not spent much time here lately owing to pressure of work and an increasing involvement in "Brave New Climate" the MWP title caught my eye. One of the things I liked was this quote from Zhang et al. (2003): QUOTE ... We find that the annual growth rings mainly reflect variations in regional spring precipitation........ UNQUOTE I think this implies that dendochronology is affected by more than a single variable. If the above quote is correct April showers can have a greater effect on tree growth than average temperature. Likewise, studies of climate issues in 16th century Mexico use tree rings to track rainfall rather than temperature. Can any of you learned gentlemen explain why Michael Mann uses dendochronology to track average temperature?
       Moderator Response: [DB] Your answer is here.
87186. trunkmonkey at 14:53 PM on 30 April 2011
       Models are unreliable
       Physics does not handle emergent properties well. Life itself, while not violating the letter of the second law of thermodynamics, definitely violates the spirit. At the risk f heresy, I am confessing straight away that I believe there may be a law or two of thermodynamics undiscovered. Particularly as regards life and emergent properties. I can understand how you guys feel that if you have the physics nailed down, the paleo stuff barely matters. It's a brave new world, the Anthropocene anyway. When I hear, "The data are all bounded."; "The broad brush stokes have been made."; I caution the hubris of the cowboy who arises to find his charges have jumped the fence. Such are emergent properties. (I'm restraining myself here due to the excessive breadth of previous posts)
87187. adelady at 14:43 PM on 30 April 2011
       Medieval project gone wrong
       I have to agree about that map in figure 2. I gave up 40 mins of my life I'll never get back just tabulating and cross-matching the time periods for each graph/ area. The so-called MWP arising from this data only works if you allow 800 years (700 to 1500, more if you include all of the SH records), and overlook the fact that some areas show cooling smack in the middle of the range. And the NH and SH are out of synch by at least a century. Couldn't be bothered turning it into anything worthwhile. The whole idea that the graphic demonstrates anything at all is just rubbish.
87188. Tom Curtis at 14:37 PM on 30 April 2011
       How climate change deniers led me to set up Skeptical Science website
       Ken Lamber @34, Dr Trenberth's "travesty" is that "observations are inadequate to back up" just one aspect of "the theory and models". The theory and models are well supported by a range of other observations, and so are not reasonably in doubt, as Trenberth would no doubt tell you. Please note that this is not a case of an observation being made which falsifies AGW. Rather this is a case of an observation we would like to make to further support the evidence of AGW, but are as yet unable to make.
87189. Tom Curtis at 14:01 PM on 30 April 2011
       A Flanner in the Works for Snow and Ice
       Ken Lambert @141, Flanner does not, SFAIK estimate the total additional energy absorbed by the arctic (net increased energy minus net increased outgoing energy). Rather, he estimates a forcing change per degree K averaged over the Northern Hemisphere. That can be turned into a value for net additional energy simply by multiplying by the surface area of the NH and and the actual change in temperature over the period; or to an actual globally averaged forcing by halving the value and multiplying by the temperature gain. These are also appropriately called Flanner's estimates IMO in that they constitute only a change of unit, and a multiplication by the actual temperature increase. They are not a quotation, and I am never claiming to quote somebody unless I enclose the text in exclamation marks. The "estimate" you quote in the surviving part of post 141 was in error (and as that is simple arithmetic, I can only plead exceptional tiredness as an excuse). The "correct" value is Flanner's value of 6.2 W/m^2 estimate is given in my 137. Again, more correctly it is my estimate based on Flanner's figure for NH radiative forcing, but again simple arithmetic takes you from one to the other, and you can double check the arithmetic for yourself. I apologize for any confusion. Finally, even if the Flanner based estimate were 3.4*10^20 Joules rather than the better 9.17*10^20 Joules, you would still not have shown my 17 or 18*10^20 Joules per summer season (not year) estimates where incorrect. This is because those estimates were of the increase in incoming energy flux, while Flanner's is an estimate of the increase in incoming energy flux minus the increase in outgoing energy flux. To show an inconsistency you would have to show the outgoing energy flux did not increase by around 9*10^20 Joules, however, if we were to go down that route we would need to find a much better estimate of the increased incoming flux than mine (which remains a significant underestimate).
87190. Bob Lacatena at 13:34 PM on 30 April 2011
       Medieval project gone wrong
       15, scaddenp, I actually started that project, but I had access to so few of the actual papers (unless I was ready to shell out hundreds of dollars in purchases and subscriptions, just to prove a point) that I abandoned it. It was kind of fun, seeing the whole thing really crumble. In the end, though, I think Mann 2010 pretty much did what needed to be done.
87191. Ken Lambert at 13:06 PM on 30 April 2011
       Lindzen Illusion #1: We Should Have Seen More Warming
       dana1981 #103 If Lintzen is right, "we should have seen more warming", does that imply the current warming imbalance (+0.9W/sq.m) is reducing? Does anyone have later information on the summation of 2005 forcings shown at the top in Figure 1?
87192. Ken Lambert at 12:30 PM on 30 April 2011
       A Flanner in the Works for Snow and Ice
       MC #140 ( -Moderation complaint snipped- ). I might as well talk to you MC ( -Inflammatory snipped- ). Is Tom's quotation of Flannner right?: viz "More importantly for this thread, Flanner estimates that the increased net energy absorption (additional energy absorbed - additional energy lost) due to arctic sea ice melt is around 5*10^20 Joules, or approximately 42% of the conservative estimate of additional incoming energy flux. As Ken would say, this is quite close to Trenberth's figure of 3.4*10^20 Joules needed to explain melting and warming of Arctic ice." If so, have I not made my case against the 17E20 and 18E20 Joules/year numbers which Tom was talking about?
       Moderator Response: [DB] Your comment was deleted due to a pervasive use of all caps; a violation of the Comments Policy.
87193. Ken Lambert at 12:10 PM on 30 April 2011
       How climate change deniers led me to set up Skeptical Science website
       JMurphy #30 "Knowing your opinion of him and his work (you seem to view him as an "advocate of AGW", rather than a unbiased scientist seeking the facts), that is over-generous of him. Makes me wonder, though, why you haven't asked him to appear here yourself, to discuss these matters to your satisfaction." Well you have a good point JMurphy. I have emailed John Cook about it on a couple of occasions, and being respectful of the ownership of this site, I did not want to preempt what John might do. Watch this space. Dr Trenberth clearly believes in the theory and models which identify CO2GHG the main cause of the last 30 years or so of surface temperature increase. His 'travesty' is that width and breadth of observations are inadequate to back up the theory and models. His is an honest statement of the observational facts. As said previously - this can go two ways. Dr Trenberth goes for 'its there but we can't adequately measure it', and I am going for the 'if it ain't measured it might not be there', if and until the measurements say more.
87194. jyyh at 12:08 PM on 30 April 2011
       Wakening the Kraken
       Excellent, thanks and a bow. That would be 'Revontulimeri' in finnish. I might as well take the Quenya version, though the finnish language commission may have something against it.
87195. pbjamm at 10:27 AM on 30 April 2011
       Medieval project gone wrong
       Sphaerica and Philippe Chantreau Add me to your ranks as well. The utter nonsense that was put forward as fact and conspiratorial tone made it impossible for me to take them seriously. Much like the Jerry Springer show actually, which for non-americans was traditionally viewed while drunk.
87196. Daniel Bailey at 09:41 AM on 30 April 2011
       Climate Change Denial book now available!
       I must also signal for a Kindle version, John. My wife gave me one for my birthday, which I'm using to store science papers for later reading. She's threatened to repurpose the Kindle unless I download an actual book to read to it... The Yooper
87197. scaddenp at 09:31 AM on 30 April 2011
       Medieval project gone wrong
       So the obvious citizen science project would be to replicate the map but do all the graphs correctly.
87198. dana1981 at 09:18 AM on 30 April 2011
       Lindzen Illusion #2: Lindzen vs. Hansen - the Sleek Veneer of the 1980s
       As Stephen noted in #31, what matters is the net forcing, not how much came from CO2 or methane or ozone etc. Scenario B was closest to the actual observed net forcing, and I adjusted it to more accurately reflect the actual forcing in "Adjusted Scenario B." To be honest, I don't really know what point johnd is trying to make.
87199. Bob Lacatena at 09:17 AM on 30 April 2011
       Lindzen Illusion #2: Lindzen vs. Hansen - the Sleek Veneer of the 1980s
       30, johnd,

       In order to claim that the Hansen Scenario B is the closest to reality is to accept that each of the above has come to pass, otherwise any similarity of the prediction to reality is more due to accident rather than design.

       You don't seem to understand matters. The scenarios aren't predictions, they're... scenarios. Hansen isn't and was never in the business of predicting economic growth and fossil fuel use, and he couldn't very well make a prediction for every possible variation in CO₂ output. So he came up with three broad scenarios modeling future CO₂ emissions, each using a set of assumptions. That the assumptions were wrong, but reality's CO₂ levels track closer to one scenario than the others, and so makes the predictions which accompany that scenario the best to consider. It's one thing to claim his climate predictions were wrong (which they obviously weren't), but... to claim his economic "predictions" were wrong? Sheesh.
87200. Tom Curtis at 09:14 AM on 30 April 2011
       Lindzen Illusion #2: Lindzen vs. Hansen - the Sleek Veneer of the 1980s
       johnd @30, Hansen described three scenarios. In order to claim that scenario B is closer to reality than either of the others we need only show that it is closer to reality than either scenario A or C - which it is. Are you seriously suggesting that because Hansen's scenario B (not prediction, bu scenario) is not a perfect match to reality that denier's continuously insisting that scenario A is a better fit is justified?

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