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Comments 93801 to 93850:

93801. Kevin C at 07:42 AM on 5 March 2011
       Roy Spencer’s Great Blunder, Part 3
       Just done a quick confirmation. Here is a graph of the PDO (false scale), a 30 year exponential, and the convolution of the exponential with the PDO, which is Arthur's function Q(t): Q(t) is simply the PDO with an asymmetric smoothing. To a good approximation we could say it has been smoothed and then lagged by about a decade. If Arthur is right, then if we add the exponential (scaled by some factor) to Q(t), then we should be able to get Spencer's model. Or Barry's figure 8 by using different scales for the exponential term. Here goes: That's pretty close. Looking back at Barry's figures, Spencer has applied an extra pre-smoothing to the PDO, which accounts for the remaining difference. So what happens if we go to the future? Well, the exponential term is pretty near zero by 2000, so all that is left is the smoothed PDO. Hence Spencer is predicting cooling as the PDO goes negative. What about the past? I think you can see where the exponential is going. Snowball earth in 1800, Pluto a little earlier.
93802. apsmith at 07:42 AM on 5 March 2011
       Roy Spencer’s Great Blunder, Part 3
       Kevin C - good point on the transient bit blowing up into the past, I was trying to get to the bottom of that with Barry B. over email just now. In reality it is legitimate to have some transient value as a substitute for the missing forcing data before the starting point in the model (if you start just at T = T_e then you're saying there was no effect of forcing on temperature before the start). But to have such a large negative starting anomaly requires the forcing to have been large and negative in the prior period - and as we see from the MacDonald data it actually was quite close to zero for the few decades before 1900.
93803. robert way at 07:42 AM on 5 March 2011
       Icing the Medieval Warm Period
       Another interesting paper using low resolution proxies is Viau et al (2006) which is based on pollen records and reconstructs temperatures similar to the MWP for up to 1950. http://www.skepticalscience.com/pics/1_Viauetal2006.png
       Moderator Response: [DB] Enabled in-line graphic.
93804. robert way at 07:30 AM on 5 March 2011
       Icing the Medieval Warm Period
       Fredrik Charpentier Ljungqvist at 02:14 AM on 5 March, 2011 Dr. Ljungqvist, would you not agree however that your reconstruction of the extra-tropical northern hemisphere demonstrated that the temperatures are currently above those during the warmest decades of the MWP. I have often wondered why your 1990s decade shows lower temperatures than the 1980s and correspondingly why the instrumental record for the 2000s was not plotted. Nevertheless I would wonder if perhaps results might differ if tree rings (33% of the reconstruction) were not included because they tend to have issues with low frequencies. Either way I do agree that proxy data from the southern hemisphere is too sparse for global reconstructions but examples of attempts such as from Huang et al (2008) do demonstrate current global warmth exceeding the warmth during the MWP. Furthermore when we think of the most sensitive of indicators of climate change ice caps are undoubtedly amongst the most sensitive. Evidence from Anderson et al (2008) demonstrate that ice cap recession on baffin island is beyond any period over the last 1700 years. Although the results of this study are of a low temporal resolution, conclusions such that ice cap recession is unprecedented over at least the last 1700 years are assured. Each individual study obviously has their pitfalls but I do find it challenging that using annually to decadally resolved proxies for reconstructions are the only way of determining the magnitude of MWP to CWP comparisons. Perhaps Moberg's wavelet method is a plausible solution?
       Moderator Response: [DB] Enabled in-line graphic.
93805. williambaskerville at 07:00 AM on 5 March 2011
       Icing the Medieval Warm Period
       @ scaddemp "As for opinion on MWP - opinions are worthless unless based on data. For more complete picture of MWP globally, then try here." My opinions are based on data. Quite ignorant your post. Maybe you take a look on the reconstructions listed on the NOAA or my summary on mittelalterlichewarmperiode and then you get a better understanding :) @ muoncounter ".. it seems to be comparison of MWP vs. the current warm period." Yes, indeed. I don't know if medieval temperatures were warmer than the temperatures are today. I say, you can't count some glacier advances in the MWP against a MWP but on the other hand some glacier advances today not as an argument against a current Warm Period. To say: We have global warming now contra Northern Hemispheric Warming at medieval times is no argument in this case. If we had a global LIA we also had a global MWP with regional differences in warming, as we see them today. If there was no global LIA there was (at least) a bi-hemispheric MWP. Btw if the sun was the main factor in past, medieval warming, this would be an argument for a global MWP, as Dr. Büntgen stated: Gehen Sie von den möglichen Steuergrößen aus. Was bleibt übrig? Alles läuft auf dieser Skala auf die Sonne hinaus. Wenn dem so ist, müsste man sicher von einer globalen Anomalie ausgehen dürfen; natürlich durch interne Oszillationen modifiziert William
93806. thepoodlebites at 06:47 AM on 5 March 2011
       Ice age predicted in the 70s
       #39 Your Barry et al. link is broken. Read just before the sentence you quoted, "the summer cooling is apparently widespread through the Canadian Arctic so that a larger scale control must be sought." A thorough scientist will recommend the need for further study when a cause for the observed trend can not be conclusively determined.
93807. muoncounter at 06:32 AM on 5 March 2011
       Icing the Medieval Warm Period
       No, I got your argument entirely. I agree with your "LIA glaciers were increasing on a global basis," signifying a cold period. I took your earlier statement to suggest that the presence of a few 'increasing' glaciers today, along with a reference to warmer temps in the '30s and '40s, to mean that we are not in a global warm period. Most glaciers today are not increasing, as shown by the WGMP mass balance. The question is hardly a comparison of MWP vs. LIA; it seems to be comparison of MWP vs. the current warm period.
93808. scaddenp at 06:18 AM on 5 March 2011
       Icing the Medieval Warm Period
       william - it is common to quote that two valley glaciers are advancing as evidence that its cold in NZ. In fact those two are in long term retreat but advance/retreat with ENSO-driven changes in snow. Virtually all the rest of NZ glaciers are in retreat, mostly very rapid retreat. Picking one or items is Cherry Picking. Look at the overall picture. As for opinion on MWP - opinions are worthless unless based on data. For more complete picture of MWP globally, then try here. Note the marked variations when you put it all together.
       Moderator Response: [DB] Good points, all. Alpine glacier advance is a function of temperature and precipitation in the accumulation zone, with terrain and slope a modifying variable. Thus, it is quite conceivable for a few NZ glaciers to be advancing in a warmer world even though the vast majority are receding. Saying otherwise is to simply be in denial.
93809. williambaskerville at 06:18 AM on 5 March 2011
       Icing the Medieval Warm Period
       @ muoncounter "That statement holds little meaning on the global basis. Isolated increasing glacier references can indeed be found, but the entire picture is negative" So what? You did obviously not get my argument. We can turn your statement on the LIA and the MWP too. In the LIA glaciers were increasing on a global basis but some were decreasing and in the MWP the same vice versa. This does not mean that the LIA was not a global phenomenon and one of the coldest periods within the last several thousand years. This does also not contradict my opinion on the MWP as a bi-hemispheric phenomenon (for some the evidence for the Southern Hemisphere ist not "good" enough for this statement but ever since I've gone through papers of Lara, Villalba (1990a, b), Villalba (1994), Stine (1994), Thompson et al. (2000, 2006), Boninsegna et al. (2009), Ljungqvist (2009), von Gunten (2009 - Inauguraldissertation), von Gunten et al. (2009), Moy et al. (2009-Springer) and Neukom et al. (2010) on the (southern) South America and Huffman, Holmgren, Holmgren 2003, Holmgren and Öberg 2006, Robertshaw and Taylor 2000, Tierney et al, Lamb et al. 2007, Verschuren et al. 2000 and Ngomanda et al. 2007, for Africa, I am quite sure for this part too). Within the MWP - for South America more specific "the late Medieval Warmperiod" mean temperatures were warmer than in the LIA. Of course this does not mean that the mean temperatures in Europe in contrast to the temperatures of the subsequent LIA in Europe have to be the same in Africa. It depends on the region.
93810. scaddenp at 06:08 AM on 5 March 2011
       Ice age predicted in the 70s
       thepoodlebites - the question is whether the scientific consensus was that planet was cooling. You can find papers noting long term negative turn in solar forcing, and plenty on aerosol cooling but also considerable concern about warming. Was there a consensus like there is on AGW now? Was there even a slim majority worried about cooling? You can only answer those questions of with systematic survey of scientific literature, not picking papers.(eg Peterson) As for Climate Depot - how many examples of misinformation would we have to show you before you abandoned it? 5, 10, 100, every post, - or never so long as it says things you want to hear. (ie is it worth our time trying?)
93811. Alexandre at 06:05 AM on 5 March 2011
       Icing the Medieval Warm Period
       Pete Dunkelberg #24 Maybe this post about a Mann 2009 paper can be a partial answer to your second question. It's not really a time series, but two snapshots: one of the MWP temp averages over the world, and one of the Little Ice Age. You can see there many cold spots during the MWP.
93812. thepoodlebites at 05:53 AM on 5 March 2011
       It's Pacific Decadal Oscillation
       #74 Response: Thanks for the link Daniel. [OT] The title kinda reminds me of the that character on Big Bang Theory, Eric Kripke, the university bully with a lisp and Sheldon's arch nemesis. [end OT] I'm open to the idea that the 0.5 C warming in the last 30 years is both natural and anthropogenic. My argument continues to be more from natural variability than man-made CO2 induced. If the UAH annual trend continues upward this decade, >0.8 C, then I think the AGW proponents have a stronger case. If the trend is flat to cooler, <0.3 C, then the AGW case will be weaker. Sorry to hear about the failed Glory launch. We need better satellite-based measurements.
93813. muoncounter at 04:56 AM on 5 March 2011
       Icing the Medieval Warm Period
       William B: "there are glaciers increasing" That statement holds little meaning on the global basis. Isolated increasing glacier references can indeed be found, but the entire picture is negative: Annual mass balance at World Glacier Monitoring Project
93814. williambaskerville at 04:50 AM on 5 March 2011
       Icing the Medieval Warm Period
       @ JMurphy Don't be aggressive, Mr. Murphy. Infact it is maybe true that my statement is correct only for the norhern part of Scandinavia. Even if Dr. Büntgen in my interview told me: "Speziell sei noch darauf hingewiesen, dass gerade aus Skandinavien die vielleicht besten regional-scale summer, i.e. June-August temperature reconstructions based on annually measurements of conifer maximum latewood density kommen. Eine Divergenz zwischen ansteigenden Sommertemperaturen und geringerem Jahrringwachstum ist in Skandinavien eh kein Thema, da die höchsten Temperaturen in den 1930er Jahren lagen (der Sommer von 1937 war extrem warm)." http://mittelalterlichewarmperiode.blogspot.com/2010/08/menschen-im-gesprach-teil-vi.html Unless that, my argument is still correct. What do I want to proof? Nothing. I only add my opinion on the MWP and it's extend. @ Moderator Thank's I'll do so.
93815. invicta at 04:40 AM on 5 March 2011
       Icing the Medieval Warm Period
       TIS & AS thanks for the links I'll get reading
93816. Fredrik Charpentier Ljungqvist at 04:34 AM on 5 March 2011
       Icing the Medieval Warm Period
       Concerning Scandinavian temperature: It is only in the northern part of Scandinavia that temperatures were about as high in the 1930s and 1940s as in the post-1990 period. In southern Scandinavia the last two decades have been generally warmer than the 1930s and 1940s.
93817. JMurphy at 04:32 AM on 5 March 2011
       Ice age predicted in the 70s
       thepoodlebites, it is difficult to know what argument you are trying to support, especially as the first paper you linked to (W.S.Harley) also stated : "Thirty years of data are found of insufficient length to determine whether the cooling constitutes a climatic change under the given criteria"; and the second one (Barry Et al) concludes the introduction with : "The evident sensitivity of this area to climatic fluctuations on both short and long time scales makes it a rewarding area for interdisciplinary environmental studies". Is any of that evidence of anything you are trying to prove ?
93818. Pete Dunkelberg at 04:32 AM on 5 March 2011
       Icing the Medieval Warm Period
       Moderators: 1. Where did you get / how did you prepare the graphic in # 15? Could you also show the same but using, say, a 1959-1980 baseline vs 2000-2010? 2. Given the ability of Skeptical Science to present and clarify global climate, have you thought of a time series of the MWP? In other words, in a certain period of 50 to 100 years the MWP was in South America, then in the Caribbean, at another time in Europe, and at these times other regions were perhaps cool. Some newer temperature series (single spot 'hockey sticks') that have been mentioned here would be useful for this project.
       Moderator Response: [DB] That is a NASA graphic for which I lost the link (irritating, yes). However, I was able to quickly find that version on Treehugger.com (they added the obvious text, but the rest of the graphic matched my aging memory). I'll try & track down the exact NASA link. If you go to here you can create this output: The rest of your suggestion, while intriguing, would amount to repudiating a Gish Gallop, in my opinion.
93819. JMurphy at 04:13 AM on 5 March 2011
       Icing the Medieval Warm Period
       williambaskerville, a quick Google found this WIKIPEDIA page which states that, in Denmark, July 2006 was the warmest July ever and the second highest temperature ever recorded there - only beaten by August 1997. It also states that Sweden's highest daily average temperatures were in 1994 although, indeed, the highest individual temperature readings were in 1947 and 1933. It also states that many high temperature records were broken over many parts of Central and Southern Finland. What are you trying to prove ?
93820. Berényi Péter at 04:08 AM on 5 March 2011
       Climate Sensitivity: The Skeptic Endgame
       #85 KR at 15:22 PM on 4 March, 2011 Berényi - I'll admit to having some trouble following that last posting. Try harder please and you'll find it makes sense after all. The last I heard you were claiming that the relaxation time was essentially zero, so that there was no heating left in the pipeline. Now you are arguing that relaxation times are long enough to slow warming to a manageable level??? You're contradicting yourself. No, I am not. The nice thing about linear systems is that they are additive. If there are several different processes in the climate system operating on different timescales, the overall response is simply the sum of individual responses. So the impulse response function can be written as the sum of λ_k/τ_ke^-t/τ_k (if t > 0, zero otherwise) for k=1,2,...,n. Guess why the full set of (λ_k;τ_k) pairs, along with their error bars is never specified in the mainstream climate science literature. Just play with the numbers and you'll see it is entirely possible to have a pretty high equilibrium climate sensitivity (sum of λ_k's) with extremely low short term climate sensitivity (sum of λ_k's for which τ_k is small) while rate of change in response to a quasi-realistic CO₂ forcing scenario is never too steep. In fact this state of affairs is consistent with all the empirical data we have. Second, 1934 is not the start of anthropogenic carbon forcing - that's somewhere around the beginning of the industrial revolution, circa 1850 or so. Come on, the transition in the first half of 20th century was of course smooth, but the error in the response is the response to the difference between a smoothly changing excitation and this artificial one. As the difference between them is small and it was largest a long time ago (more than 70 years), the error in the climate response as of now is small. Third, relaxation times are relative to multiple time frames - from the several week H2O forcing to the multi-century ice response. Your simple formula is therefore inappropriate. And, since rate of change is dependent on scale of forcing, your 1.8C/century limit is, in my opinion, nonsense. As for the first part, see above. As for the latter part, please clarify what "rate of change is dependent on scale of forcing" is supposed to mean. Describe the dependence you think should hold in detail.
93821. williambaskerville at 03:48 AM on 5 March 2011
       Icing the Medieval Warm Period
       @ DB "No one is suggesting that the warming of the global will be a uniform or linear process. But it is indeed a global process, as you can see here" If it is ok for the current warming not to be a uniform or linear process, why it is/was not ok for the so called MWP? I am convinced that the MWP was at least a bi-hemispheric event. Unfortunately we have not enough data to give information about the existence of a "MWP" in the equatorial areas of the world. I have listed some in my post: http://mittelalterlichewarmperiode.blogspot.com/2011/01/prima-klima-am-aquator.html For me there is no doubt at all that we have hundreds of pr-papers affirming the claim of H. Lamb for the Northern Hemisphere. Even scientists, sceptical towards the terminus "MWP" say that "mean temperatures during this interval were warmer than the subsequent Little Ice Age" (P.e. Crowley, Lowery: How Warm Was the Medieval Warm Period?, in: Ambio, Vol. 29 No 1, Feb. 2000, 54). We have also evidence for the existence of a MWP in Southern America, Africa, the Antarctica and New Zealand. On the other hand it looks like that there's a broad consent within scientific community that the LIA was a global event (p.e. Wanner 2008; the newest paper by Lane et al.: Oxygen isotope evidence of Little Ice Age aridity on the Caribbean slope of the Cordillera Central Dominican Republic. They write: "Climate change during the so-called Little Ice Age (LIA) of the 15th to 19th centuries was once thought to be limited to the high northern latitudes, but increasing evidence reflects significant climate change in the tropics"). If we accept that the LIA was a global event and, as Wanner wrote, one of the coldest periods within the last several thousand years, we have imho to accept that the temperatures at the foregoing time period were warmer than they were in the LIA too. Why don`t call it MWP like Lamb called it? For me one thing is clear. If you don`t accept the MWP as a warm period you can't accept the current warm period as a warm period either. As I said before, there are glaciers increasing in the Karakorum, in Norway and New Zealand even in Argentina. Don`t you know that the highest temperatures in Scandinavia were in the 30 and 40s of the 20th century? Best William http://mittelalterlichewarmperiode.blogspot.com
       Moderator Response: [DB] Please read this post and then this post for background on the Medieval Warm Period. If you then still maintain the MWP was a global phenomenon, continue that conversation there. For posterity and context, current northern hemisphere temps greatly exceed those of the MWP: Northern Hemisphere Temperature Reconstruction by Moberg et al. (2005) shown in blue, Instrumental Temperatures from NASA shown in Red
93822. dana1981 at 03:38 AM on 5 March 2011
       Climate Sensitivity: The Skeptic Endgame
       HR #91:

       " how much of the 0.8oC would you attribute to anthropogenic GHGs?"

       About 80%.
93823. thepoodlebites at 03:34 AM on 5 March 2011
       Ice age predicted in the 70s
       #37 I find myself at a disadvantage here. If I answer your question my post most likely will be deleted, evaluated as an off-topic opinion. I'm finding the Climate Depot's link a valuable resource. I cited one peer-reviewed paper that supports my argument and I can cite many others, here. I will provide more links if this post is not deleted. Richard Feynman's first principle of scientific integrity states "you must not fool yourself, and you are the easiest person to fool. After you have not fooled yourself, it's easy not to fool other scientists." This first principle should be applied to everybody in equal proportion.
93824. les at 02:23 AM on 5 March 2011
       Climate Sensitivity: The Skeptic Endgame
       Sorry Eruc; CERN doesn't just use them for QM - far from it. The fact is that such techniques are widely used and yield useful results -and probabilities, not "probabilities" - in all kinds of situations. Ofcourse they, like all techniques, can be used well or badly. That has to be argued, per application, on individual merits ... or, if you prefer on your POV
93825. Fredrik Charpentier Ljungqvist at 02:14 AM on 5 March 2011
       Icing the Medieval Warm Period
       There have been a lot of discussions about the spatio-temporal pattern of the Medieval Warm Period in the last two decades. But the statements, often made, that the evidence for a Medieval Warm Period is most clear in Europe simply does not hold true. The evidences are in fact even better, and more numerous, from China. Also, the data from Greenland are quite good. I do not know why the Chinese scholarship, mostly published in English, so often are overlooked in the context of the Medieval Warm Period. This is a pity! The second half of the 10th century was pretty warm, well above the 1961–1990 mean, in most regions in the extra-tropical Northern Hemisphere where we have data (China, Europe, Greenland, Alaska, and Siberia). The data from the tropics and Southern Hemisphere still too spare to say anything certain still about the amplitude and extent of the Medieval Warm Period compare to the recent warming. What we do know is that it was synchronically warm in Greenland, Europe and China, and Siberia as well as, probably, over large parts of North America, c. AD 950–1050. Only this time interval shows evidence of coherent warm conditions in multiple regions. Later in medieval times (and earlier) the conditions were more geographically heterogeneous although quite similar still in Europe and China.
       Moderator Response: [Daniel Bailey] Thank you for taking the time to share your perspectives and expertise, Dr. Ljungqvist. An expert's presence is always welcome here.
93826. bbickmore at 02:03 AM on 5 March 2011
       Roy Spencer’s Great Blunder, Part 3
       Alexandre, I have no idea how reliable it is, except that it is pretty accurate for the 20th century. I believe I linked to both data sets.
93827. Alexandre at 01:49 AM on 5 March 2011
       Roy Spencer’s Great Blunder, Part 3
       Kevin C # 15 & 16 Thanks. Yes, I understood that too (even if more superficially and intuitively than your explanation). Spencer's model just yields absurd results as we get further from the calibration period. My question was not regarding the analysis of Spencer's work, but the certainty of the reconstruction itself. There's a quite popular meteorologist here in Brazil that uses the PDO argument now and then, and I'd like to know how much I can depend on that kind of long term reconstruction to make a counter-argument.
93828. Eric (skeptic) at 01:18 AM on 5 March 2011
       Climate Sensitivity: The Skeptic Endgame
       les, being proper for quantum mechanics at CERN doesn't justify creating distributions for climate parameters that are completely described by classical mechanics. It impacts the policy debate only because the resulting "probabilities" are (from my POV) easy to unravel. E.g., someone links to a paleoclimate sensitivity argument and I simply point out the red boxes in Knutti, figure 3, that were left out of the figure 3 above (measurements for probabilityy distribution were not made with current climate)
93829. Arkadiusz Semczyszak at 01:11 AM on 5 March 2011
       Icing the Medieval Warm Period
       ... a propos Anasasi - generally: the drought in MWP. From the papers cited here: Land surface temperature changes in Northern Iberia since 4000 yr BP, based on δ13C of speleothems, Martín-Chivelet et al., 2011.: - “... 1350–750 yr BP warm period (Medieval Warm Period) punctuated by two cooler events at ~ 1250 [!] and ~ 850 yr BP ...” The same can be seen and here: Ababneh, 2006. Hence the declaration: “This drought marks the middle of the Medieval Warm Period - an interval of warmer temperatures between approximately AD 800-1300 characterized by greater drought duration and frequency in the Northern Great Plains compared to more modern times.” by Stambaugh et al., 2011.; does not give decisive argument to statements: drought = MWA - even regionally.
93830. Kevin C at 01:05 AM on 5 March 2011
       Roy Spencer’s Great Blunder, Part 3
       One other thought: With Arthur's equation we can now run Spencer's model *backwards* through time using Spencer's parameters. The exponential decay of the transient becomes an exponential growth. The size of the transient at 1900 looks to be about -0.4C. An exponential with period of 30y multiplies by about 25 times every century. That means by 1800 it would be about -10C, by 1700 the temperature of the earth would have been approaching absolute zero. No matter how big the PDO, there's no way it can overcome an exponential.
93831. James Wight at 00:43 AM on 5 March 2011
       Putting a new finger on climate change
       “10 fingerprints: Make room for Number 11 (gonna need a bigger glove).” Actually, make that number 12. Climatologists have recently found a human fingerprint in intense rainfall: Two seminal Nature papers join growing body of evidence that human emissions fuel extreme weather, flooding that harm humans and the environment
93832. les at 00:31 AM on 5 March 2011
       Climate Sensitivity: The Skeptic Endgame
       90 Eric:

       when I see a probability distribution I immediately look around for the data it was based on.

       well yes. but now you have seen that that is not the only sort of probability distribution, and really - as a remark on the general technique, rather than the objective/subjective side issue - it is a perfectly proper technique which lots of science uses (e.g. CERN wouldn't work without it). In my limited experience of them, however, they are rarely used to determine The Truth, but to bound understanding and projections... as, IMHO, they are being used here. As for policy, it's also an issue with lots of obfuscating ideas, like intergalactic cosmic ray flux, and the demand that things are more absolute that is ever the case in reality, put about by people who probably actually know better... which is definitely off topic.
93833. HumanityRules at 00:28 AM on 5 March 2011
       Climate Sensitivity: The Skeptic Endgame
       "If the IPCC climate sensitivity range is correct, if we were to stabilize atmospheric CO2 concentrations at today's levels, once the planet reached equilibrium, the radiative forcing would have caused between 0.96 and 2.2°C of surface warming with a most likely value of 1.4°C. Given that the Earth's average surface temperature has only warmed 0.8°C over the past century" Dana how much of the 0.8oC would you attribute to anthropogenic GHGs?
93834. Arkadiusz Semczyszak at 00:01 AM on 5 March 2011
       Putting a new finger on climate change
       @Marcus CO2 poorer in 14C and 13C - may have come from fossil fuels, but also from the soil, or deep ocean. Nowinski et al., 2010.: “Radiocarbon ages of heterotrophically respired C ranged from <50 to 235 years BP in July mineral soil samples and from 1,525 to 8,300 years BP [!] in August samples, suggesting that old soil C in permafrost soils may be metabolized upon thawing.” Upper-ocean-to-atmosphere radiocarbon offsets imply fast deglacial carbon dioxide release, Rose et al., 2010. : “The atmospheric decrease in the radiocarbon signal coincides with regionally intensified upwelling and marine biological productivity ... ..., suggesting that CO2 released by means of deep water upwelling in the Southern Ocean lost most of its original depleted-14C imprint as a result of exchange and isotopic equilibration with the atmosphere.” Oxygen ... - we can not be attributed strictly decrease atmospheric O2 of A. CO2. A conceptual model for the temporal spectrum of oceanic oxygen, Ito and Deutsch, 2010.: “Observed across the world oceans in recent decades have been interpreted as a response of marine biogeochemistry to climate change. Little is known however about the spectrum of oceanic O2 variability [...].” “We find a statistically significant spectral peak at a 15–20 year timescale in the subpolar North Pacific [background], but the mechanisms connecting to climate variability remain uncertain.” On evaluating ocean models with atmospheric potential oxygen, Naegler et al., 2006.: “We used observed and simulated atmospheric potential oxygen (APO) to evaluate simulated air-sea flux fields from 11 ocean global carbon cycle models. APO is defined in terms of atmospheric CO2 , O2 and N 2 so as not to depend on terrestrial photosynthesis and respiration. Hence, it is in principal suited to evaluate simulated air-sea fluxes of these gases.” “The simulated amplitude of the seasonal APO variability was generally less than observed. We conclude that it is difficult to validate ocean models based on APO because shortcomings in atmospheric transport models and problems with data representativity cannot be distinguished from ocean model deficiencies.”
93835. Kevin C at 23:58 PM on 4 March 2011
       Roy Spencer’s Great Blunder, Part 3
       Alexandre@14: I think the point now is that it doesn't matter. Based on Barry's post, it might have been valid as a test of predictive power. Indeed, the question of whether Spencer's model had any predictive power should have been tested by Spencer in the first place. However, after Arthur's analysis it is kind of irrelevant. All the model consists of is a target temperature, an initial transient from which temperature decays exponentially towards the target temperature, and a forcing which also has an effect which decays exponentially. In fact, you can preconvolute the forcing to get Arthur's Q(t), and you just have a linear combination of the transient and Q. The transient is clearly meaningless - it's an arbitrary parameter and it's effect depends totally on when you start your simulation. And yet without it, Spencer's model can't even produce the rising temperature from 1910-1940.
93836. Alexandre at 23:42 PM on 4 March 2011
       Roy Spencer’s Great Blunder, Part 3
       How robust is the MacDonald and Case (2006)PDO reconstruction? To what extent can we rely on that as an accurate series?
93837. gallopingcamel at 23:33 PM on 4 March 2011
       Icing the Medieval Warm Period
       [ -Edit: Complaints about moderation removed- ] However this post speaks directly to the relation between historic events and climate, a special interest for me. I applaud the author for providing several interesting links. After reading everything that was not behind a pay wall, I was encouraged to find that the Martín-Chivelet et al abstract claims clear correlations with ice core data and historical events such as the Roman and Medieval Warm Periods. Thank you for an excellent post Daniel Bailey although it does pretty much the opposite of what the title suggests. As Willam of Baskerville says this is not an argument against the MWP. For example, here is the concluding paragraph from Matin-Chivelet et. al: "Spectral analysis of the time series shows consistent climatic cycles of ~ 400, ~ 900 and ~ 1300 yr, comparable with those recognized in the North Atlantic marine record, the Greenland ice cores, and other terrestrial records for the middle – late Holocene, suggesting common climate forcing mechanisms related to changes in solar irradiance and North Atlantic circulation patterns."
       Moderator Response: [DB] Actually, all the data we have shows that the MWP to not be an analog for modern warming in both scope and degree. In addition, the available data shows the MWP to be a heterogeneous mix of cooling, warming and drought over similarly varied geographic and temporal areas. And what warming data there is for the MWP shows it to fall short of the warming of the last 30 years, which is now comparable to levels last achieved in the Holocene Altithermal.
93838. Arkadiusz Semczyszak at 23:27 PM on 4 March 2011
       Icing the Medieval Warm Period
       @Robert Way I do not know all the work of J. Zasadni, perhaps this applies only to the Zillertal
93839. Arkadiusz Semczyszak at 23:20 PM on 4 March 2011
       Icing the Medieval Warm Period
       I think that this publication speaks in a way that best condensed - all: Climatic fluctuations in the Central Region of Argentina in the last 1000 years, Cioccale, 1999.: “The Medieval Warm Period was characterized by a humid and warm climate in the plains and recession of the Andean glaciers. In contrast, during the Little Ice Age the plains had temperate, semi-arid to arid climates, and Andean glaciers advanced.” The “fall” of civilization that (so far) is always cool - never warming.
93840. Eric (skeptic) at 23:19 PM on 4 March 2011
       Climate Sensitivity: The Skeptic Endgame
       les, my advice to poptech is Choose One (objective or subjective). I have always had an objectivist philosophy (although not perfectly matched to Randianism), so when I see a probability distribution I immediately look around for the data it was based on. Often there is literally none. As for your policy argument, we are not facing unknowns like one or more typhoid Marys or a human-based decision to go to war. It is simply a complex natural process with some true unknowables like intergalactic cosmic ray flux, future volcanic activity, future solar activity (known to some extent), etc. A lot of these are ambiguous or more likely to cool, so not really worth debating. Everything else is knowable. There is no reason to apply subjectivity to the issue of sensitivity, just better models, validated against real world measurements. The bottom line is that 5C warming (or choose your favorite number) has a zero or a 100% probability of happening within time X (choose 100 years but not 1000), under specific conditions such as BAU. That statement contains no room for any subjectivity other than BAU being made as a human choice which is really only a marginal issue.
93841. mspelto at 23:18 PM on 4 March 2011
       Icing the Medieval Warm Period
       There are a few advancing glaciers, but most of the advances are quite limited and hence not overrunning developed forest vegetation. The evidence uncovered here is pretty systematic for the time periods noted in Table 1. The difference between a glacier advancing and disappearing like Helm Glacier, one of the sample sites is vast.
       Moderator Response: [DB] Thanks, Mauri!
93842. williambaskerville at 22:49 PM on 4 March 2011
       Icing the Medieval Warm Period
       Hi, I don't think this is a argument against the MWP. Don't we actually have increasing glaciers in Norway, New Zealand and the Karakorum? Don't we have regions in the world, not getting warmer? I am writing about this on my post "Nicht alle Gletscher schrumpf(t)en" (Not all glaciers we/a-re melting) http://tinyurl.com/64kmfuj If you want to read more, take a look on my German blog: http://mittelalterlichewarmperiode.blogspot.com Feel free to post comments!! Best Willam of Baskerville Ps. I've made interviews on this topic - MWP - with scientists like Dr. Heinz Wanner, Dr. Ulf Büntgen, Frederic Ljungqvist and others.
       Moderator Response: [DB] No one is suggesting that the warming of the globe will be a uniform or linear process. But it is indeed a global process, as you can see here:
93843. robert way at 22:44 PM on 4 March 2011
       Icing the Medieval Warm Period
       The LIA in the alps did not end in 1950. That's a complete fallacy and is not supported by the literature at all. You might find one paper where a small portion advanced during that period but the fast majority of glaciers in the alps had their LIA between 1750 and 1850.
93844. Kevin C at 22:39 PM on 4 March 2011
       Roy Spencer’s Great Blunder, Part 3
       Here's a graph of the 1000 year PDO forcing used to drive the 1000 year simulation in figure 10. I just took the Macdonald and Case data and applied a 19 year moving average. Comparing this with figure 10, it is now obvious that Spencer's model starts from an initial temperature set by the ΔTo value (off the bottom of the graph in this case) and constantly heads towards towards a temperature set by the equilibrium temperature and the current value of the forcing term.
93845. Arkadiusz Semczyszak at 22:32 PM on 4 March 2011
       Icing the Medieval Warm Period
       #The Inconvenient Skeptic ... a propos China I would add: Characteristics of cold–warm variation in the Hetao region and its surrounding areas in China during the past 5000 years, Li et al., 2010.: “1450 - 1000 cal yr BP: The climate was relatively warm compare with the temperature of its adjacent periods but less so than the degree of warmth at 5000 cal yr BP. This period corresponded to the Medieval Warm Period.”
93846. Arkadiusz Semczyszak at 22:20 PM on 4 March 2011
       Icing the Medieval Warm Period
       @Marcus Not so long ago in my TV - Professor L. Thompson - explaining the length of the Maya (more than 5 thousand. years) - his last end, he showed how in the Andean glaciers have advanced so quickly - it now - going back - glaciers reveal - frozen, “of unimpaired quality” plants ... Droughts - in this period of strong cooling (Neo-glacial) - covered most of the two continents of America. The same drought (cooling effect) destroyed the civilizations of the Sahara and Middle East. Stable isotopes of a subfossil Tamarix tree from the Dead Sea region, Israel, and their implications for the Intermediate Bronze Age, Frumkin, 2009.: “The Sedom Tamarix demonstrates a few hundred years of 13 C and 15 N isotopic enrichment, culminating in extremely high δ 13 C and δ 15 N values. Calibration using modern Tamarix stable isotopes in various climatic settings in Israel shows direct relationship between isotopic enrichment and climate deterioration, particularly rainfall decrease.” “This was apparently the most severe long-term historical drought that affected the region in the mid-late Holocene.” Lonie Thompson explained that the Atacama desert in the Quaternary, only once was inhabited by people - during MWA ... During the Roman maximum - period; around Masada was warmer and wetter - growing bushes Tamarix at the point where today it is a desert. Climatic effects on the δ 18 O and δ 13 C of cellulose in the desert tree Tamarix jordanis, Lipp et al., 1996.: “Since the Roman period, RH at Masada decreased by about 17% [!], while the δ 18 O value of local groundwater remained similar to present-day values, suggesting that changing atmospheric circulation has played a role in climate change in the Middle East over the past two millennia.” Polish scientist J. Zasadni, from the Institute of Geological Sciences, Jagiellonian University, who is preparing a doctoral thesis about shifting of glaciers in the Alps - Zillertal, after many years (and very precise) research - argues strongly that: in the days of ancient Rome and later - warming in the Middle Ages - expiring on the late fourteenth century, frequented alpine glaciers coverage certainly considerably smaller than today. LIA in the Alps ended only in 1950 ... Anasazi - “During the Pueblo II period, from 900-1100 CE, these designs were made even more bold, and the Anasazi (Hisatsinom) began to build kivas, or communal rooms for ceremonial purposes in their villages. Their population increased, and during this period small Anasazi villages began to spread throughout the southwest.” “During the Pueblo III period from 1100-1300 CE, the Anasazi (Hisatsinom) began to build the cliff dwellings for which they are most well-known. Many buildings in these villages under the cliffs were several stories tall.” „For unknown reasons, near the end of this period the western Anasazi (Hisatsinom) sites were completely abandoned, while the eastern sites continued to flourish and expand.” ... circa 1270-1300 - the beginning of the LIA in America ...
93847. RSVP at 22:05 PM on 4 March 2011
       Icing the Medieval Warm Period
       "It's cold out!"... and I am suppose to believe it should be colder on average, and that the world would be better off if this were the case. As long as the price of fossil fuels is rising faster than the temperature, it's hard to imagine how winters of the future are going to be more confortable.
93848. les at 22:03 PM on 4 March 2011
       Climate Sensitivity: The Skeptic Endgame
       83 Eric objective/subjective?!?! now you sound like Poppy Tech!! ;) ;) < big wink > sure, though. of course for scientists that's fine. Governments rarely have the luxury - as I pointed out to someone: armies have to be maintained without knowing the exact probability of war or invasion, hospitals and school have to be build with out knowing exactly the population in 20 years, vaccines have to be stockpiled without knowing the exact epidemiology or the next flu outbreak etc. etc. Power security has to be maintained, the environmental resources managed, healthy environment preserved (or restored)... better to understand the proper meaning of likelihood rather than stuffing it in quotes and pretending it's meaningless.
93849. Kevin C at 21:50 PM on 4 March 2011
       Roy Spencer’s Great Blunder, Part 3
       APSmith@11: That's a beautifully clear analysis and probably the definitive one, at least for anyone who can (still) solve a differential equation. It leaves me banging my head asking 'why didn't I see that straight away'? To many computers are bad for the brain. We've forgotten the power of algebra!
93850. The Inconvenient Skeptic at 21:23 PM on 4 March 2011
       Icing the Medieval Warm Period
       Here are some paleoclimate studies from China. http://epic.awi.de/Publications/And2005g.pdf http://www.sciencedirect.com/science?_ob=ArticleURL... http://hol.sagepub.com/cgi/content/abstract/13/6/933 ftp://ftp.ncdc.noaa.gov/pub/data/paleo/historical/china/china_winter_temp.txt None of these are records from Chinese history, but nodern (non tree-ring) reconstructions.

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