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Comments 118801 to 118850:

118801. Riccardo at 09:12 AM on 24 May 2010
        Robust warming of the global upper ocean
        hadfield, actually Trenberth 2010 is calling for more and better data: "This discrepancy suggests that further problems may be hidden within the ocean observations and their processing. It also highlights the need to do better, and the prospects for that." John, the link to Lyman is still broken in the caption of fig.2. Link to Trenberth is broken both in the caption and in the text.
        Response: Okay, I think all the broken links are now fixed, all 7 of them. Not my best work.
        
118802. Doug Bostrom at 09:06 AM on 24 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        What an odd remark, coming from the person who is on record as saying has anyone happened to notice that this study is basically about fishing for sardines when the title of the paper is Late-twentieth-century warming in Lake Tanganyika unprecedented since AD 500. Why would Chris be the one to complain that someone else can't grasp what the central conclusion of the paper is despite it being in black and white? Chris has pointed out that the paper's central finding is entirely in keeping with much other research conducted elsewhere by other parties. Once again we're faced with what some folks claim are conclusions based on flawed data coincidentally resembling other independent findings. This resort to unknown, unstated defects as a counterargument is an yet another eerily familiar aspect to the paper at hand; we are expected to believe that all research in polyphony confirming what is expected as a result of predictions from physics is flawed yet produces congruent findings. How likely is that? This is becoming quite boring.
118803. johnd at 08:51 AM on 24 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        chris at 08:28 AM, all I can suggest is that you contact the authors direct and complain that what you describe as secondary aspects, namely using the study to find any connection between declining primary productivity and rising temperatures, and the implications it has for the fisheries, has in your opinion taken the focus off what you consider the primary aspect, which appears to be of providing further proof of AGW. Perhaps they will issue a revision that better suits your interpretation of their work. Lets us all know what response you get. It appears as if here in this thread we see a classic example of the confusing of cause and effect, and the difficulty many have of relating their theoretical readings to the real world.
118804. chris at 08:46 AM on 24 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        johnd at 06:46 AM on 24 May, 2010 That's really desperate johnd. If you've got a quibble with the data from the cores then define it - vague aspersions relating to some unspecified "certain graphs" and "perceived flaws" is scientifically meaningless. In any case the core proxy temperature data weren't spliced as is obvious from the Figure in the top article (and Figure 2 of the paper). The data from each core is displayed as a seperate line. In this case confidence in the equivalence of the cores results from the facts that: (i) the cores were from the same location. (ii) the analyzed proxies are identical. (iii) analysis of the core stratigraphy allowed a temporal alignment of the end of the long KH1 core with the start of the short MC1 core. (iv) the reconstructed temperatures during the regions of core overlap (top of KH1 with bottom MC1) are very similar. (v) the reconstructed productivity proxy (biogenic silica) during the regions of core overlap (top of KH1 with bottom MC1) are very similar. (vi) the reconstructed charcoal content during the regions of core overlap (top of KH1 with bottom MC1) are also similar.
118805. chris at 08:28 AM on 24 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        johnd at 06:24 AM on 24 May, 2010 johnd, you're grasping at straws here. And why the efforts to shift the essential observations of this paper to secondary aspects? I noticed this paper before it was described on this site. It didn't really seem that big a deal to me. The data indicate that the very marked surface warming of Lake Tanganyika has likely produced temperatures higher than found for the last 1500 years, and that proxy estimates of primary productivity and temperature show an inverse relationship over this period (there's also an interesting mild warming temporally displaced from the Medieval Climate Anomaly that are observed in N. hemisphere temperature reonstructions). Those are the essential points aren't they? Otherwise the rest is interpretation. The high surface water temperatures are not really very surprising. These are well documented - e.g. see a very detailed analysis of Lake Tanganyika warming published last year [*]: [*] Verburg, P. and Hecky R. E. (2009) The physics of the warming of Lake Tanganyika by climate change Limnol. Oceanogr., 54, 2418–2430. abstract here Likewise Verburg and Hecky analyze primary productivity and show that this has decreased during the 20th century, and also conclude that warming may be contributing to the reduction in per-effort fish yields in the lake. Large lakes worldwide are warming in response to atmospheric radiative imbalance caused by enhanced greenhouse effect. [**] Similar data on 20th century warming and reduced primary productivity has been measured for Lake Malawi [***], etc. etc.: [**] Schneider, P., et al (2009), Satellite observations indicate rapid warming trend for lakes in California and Nevada Geophys. Res. Lett., 36, L22402 abstract here Vollmer, M. K. et al (2005) Deep-water warming trend in Lake Malawi, East Africa Limnol. Oceanogr. 50: 727–732 abstract here So the essential new data presented by Tierney et al (2010) is (i) to extend the direct measure of lake surface temperature through the last century back around another 1500 years by using paleoproxy temperature data, (ii) to document an inverse relationship between primary productivity and temperature during this period, and (ii) to highlight what looks like a mild warming period that seems temporally displaced from the N. hemisphere Medieval Climate Anomaly documented in other paleoanalyses. That's what the paper's about. It says so in the title and the abstract and the text and the Figures and their legends. The interpretation that the apparently unprecedented warming is due to global warming is pretty straightforward in the light of data from seas, lakes, land and atmosphere from 1000's of sources. It seems a straightforward interpretation that the warming "has potentially important implications for the Lake Tanganyika fishery".
118806. hadfield at 08:27 AM on 24 May 2010
        Robust warming of the global upper ocean
        In all these discussions, it's wise to remember that our ability to track ocean heat content changes to the accuracy shown in the figures (say 1-2 x 10^22 J) is very new. It results from a combination of two things: Argo and some very careful reanalysis of XBT data. As recently as 2005, the accepted time series of ocean heat content (Levitus et al 2005, Figure 1) showed a peak in OHC centred ~ 1980 and a drop of 5 x 10^22 J between 1980-1985. People were wondering why the OHC variability in climate models did not match the observations. It turns out (Levitus et al 2009, Figure 1) that this variability was over-estimated due to instrumental problems. The Lyman et al work (Figures 1 and 2 in this post) still shows quite large discrepancies between different analyses and I for one am sceptical that the data are accurate enough to support Trenberth's confident assertions about "missing heat" over a period as short as 5 years. Refs: Levitus, S.; Antonov, J.I.; Boyer, T.P. (2005). Warming of the world ocean, 1955-2003. Geophysical Research Letters 32(L02604): doi:10.1029/2004GL021592 Levitus, S.; Antonov, J.I.; Boyer, T.P.; Locarnini, R.A.; Garcia, H.E.; Mishonov, A.V. (2009). Global ocean heat content 1955–2008 in light of recently revealed instrumentation problems. Geophys. Res. Lett. 36.
118807. scaddenp at 08:19 AM on 24 May 2010
        Climate's changed before
        Roger - you cannot prove things in science; leave that to mathematics. What you can do is show that observations match the predictions of a theory. For a theory to be replaced, then you did to show either that it makes predictions that are not substantiated by observation within limitations of error, or, better, an alternative theory that explains the observation better. So far, there is a no competitor to the current theory of climate. You asked for empirical evidence,we showed it to you. You assert "he fact that there are well documented and general agreement that there have been previous warmings, such as the Holocene Maximum, the Minoan Warming, the Roman warming and the Medieval Warm Period, which are recorded in history as well as scientific proxies and the like, make CO2 as the root cause of global warming even less likely." This is not true. You plug the known forcings into exactly the same theory of climate and you get the observed warmings within the error for estimating both climate and forcings. Are you aware of the Mann 2009 paper on MCA by the way? You statements on MWP make me suspect otherwise. What we can also observe is that the forcings operating in these past periods are not operating today or even in reverse (eg Milankhovich). Now it is possible that there is some undiscovered energy transfer going on that has somehow eluded us - but that is not the way to bet in a very high stakes game. The empirical observations give us confidence that there is a GHG forcing of the right magnitude to induce current warming. Furthermore, the observations of the upper stratosphere cooling are very hard to reconcile with any other forcing.
118808. JMurphy at 08:17 AM on 24 May 2010
        Volcanoes emit more CO2 than humans
        Eric (skeptic), we should be grateful that the EU has made such cuts, otherwise the increase in CO2 would be even greater now with the volcanoes added input. Just think how worse things would be if the EU hadn't made those cuts - especially if the volcano were to continuing erupting such amounts for a full year, which is unlikely.
118809. Riccardo at 07:24 AM on 24 May 2010
        Has the greenhouse effect been falsified?
        Berényi Péter, while i can see logic of the sequence in the book, i still can not understand your point. Why did you show that sequence of graphs? The extreme -90 °C case in winter in Antarctica (presumably Vostok), what has to do with fig. 1 here taken at Barrow at a temperature of about 0 °C? Leave the "cooling effect" aside. Remember that 20 Km above the surface in Antarctica is well inside the stratosphere and temperature increases with altidude there. What you improperly call "cooling effect" is just emission from the stratosphere at a higher temperature than the ground. It's always there.
118810. Doug Bostrom at 07:00 AM on 24 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        As a point of reference, perhaps it would be useful to have the abstract available here directly: Late-twentieth-century warming in Lake Tanganyika unprecedented since AD 500 Jessica E. Tierney1, Marc T. Mayes1,2, Natacha Meyer1, Christopher Johnson3,4, Peter W. Swarzenski5, Andrew S. Cohen3 & James M. Russell1 Instrumental observations suggest that Lake Tanganyika, the largest rift lake in East Africa, has become warmer, increasingly stratified and less productive over the past 90 years (refs 1,2). These trends have been attributed to anthropogenic climate change. However, it remains unclear whether the decrease in productivity is linked to the temperature rise3, 4, and whether the twentieth-century trends are anomalous within the context of longer-term variability. Here, we use the TEX86 temperature proxy, the weight per cent of biogenic silica and charcoal abundance from Lake Tanganyika sediment cores to reconstruct lake-surface temperature, productivity and regional wildfire frequency, respectively, for the past 1,500 years. We detect a negative correlation between lake-surface temperature and primary productivity, and our estimates of fire frequency, and hence humidity, preclude decreased nutrient input through runoff as a cause for observed periods of low productivity. We suggest that, throughout the past 1,500 years, rising lake-surface temperatures increased the stratification of the lake water column, preventing nutrient recharge from below and limiting primary productivity. Our records indicate that changes in the temperature of Lake Tanganyika in the past few decades exceed previous natural variability. We conclude that these unprecedented temperatures and a corresponding decrease in productivity can be attributed to anthropogenic global warming, with potentially important implications for the Lake Tanganyika fishery. As a layman, if I concur w/johnd on any point it's probably down to conclusions beyond the temperature signal indicated as the primary result of the paper but frankly my opinion on that is not worth much. On a tangential note, the discussion here is exemplary of how much friction is introduced when an article cannot be read in its entirety because of proprietary concerns, in this case the need for Nature to balance its books so it may continue to publish.
118811. johnd at 06:46 AM on 24 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        Something that should have been raised, but wasn't, is the matter of the splicing of the data obtained from the core samples together. Recently the matter of splicing temperature data in graphs was the subject of intense scrutiny and debate with certain graphs rejected because of some perceived flaw. So what is different here? The only difference perhaps is that there is no other benchmarks that can validate or otherwise the appropriateness of splicing this particular set of data. Where are all those posters critical of the temperature graphs? Any comments that remain consistent with similar previous critical analysis?
118812. johnd at 06:24 AM on 24 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        mike at 17:51 PM, perhaps everyone needs to clear all preconceptions and agendas from their minds and get back to the basics by reading past the headlines for a change and locating what are the central issues addressed by both the study and this thread. If you haven't read the lead post of this thread in it's entirety there were two, and only two questions posed which should have provided a clue to those alert enough as to what the central issue was. The questions are 1. "What effect does temperature have on the lake's sardine population?" 2. "How does temperature affect primary productivity?" Sardines are mentioned four times, primary productivity eight times. Additionally the abstract for the article published in Nature concludes with the following statement, "We conclude that these unprecedented temperatures and a corresponding decrease in productivity can be attributed to anthropogenic global warming, with potentially important implications for the Lake Tanganyika fishery." In addition the study did the following, It measured evidence of historic productivity. It attempted to correlate recent temperatures with recent productivity. Finally it reached conclusions about future fishery productivity, of which sardines are the primary catch. What this thread makes painfully obvious is how easy it is for some people to be led simply by placing a notion in their mind so that everything after that then becomes related to that notion and used to further support what they now believe, even if it has to be distorted to do so. Before I go on perhaps you should go back to the lead post posted by John Cook, plus read the article in question through to the conclusions, or failing that, the abstract just to clarify what were the questions that the study set out to answer and what were the conclusions reached. Having said all that, with your background you probably appreciate how big an area the lake covers, about 700km by 50km, and just how variable everything could be over such a vast area. There is quite a bit of literature available from previous studies, and as one might expect, some of them note how highly variable many of the relevant factors and indicators are. Lake surface temperatures in different locations can vary by 4 degrees at a given time, climatic conditions vary so that different winds and currents mean local conditions vary across and around the lake, and so too do the fish catches across the different regions of the lake. Given the study was based on collecting samples of BSi which is considered an indicator of primary productivity, and there is information that primary productivity from the lake is not only declining but highly variable across the regions, whilst data indicating such may be available for current and recent times, core sampling has to be undertaken to obtain historical data. This brings us back to the point I have been making all along, I have serious doubts that a single core sample can represent all the variables that form part of subject being studied, namely primary productivity, in particular sardines, as so clearly stated in the lead post of this thread. With you background I imagine that you are aware of how often it has happened, often famously or more often, infamously, where on the basis of a single sample, major new discoveries have been announced only to fizzle out when it was found that the single sample was anything but representative. Perhaps you have heard of Bre-X where after the initial euphoria of a major discovery failed to be sustained, those involved then worked hard to ensure the evidence being collected matched the expectations created by the initial discovery, the similarity not lost when some of the work on tree proxy reconstructions was closely scrutinised.
118813. Berényi Péter at 05:51 AM on 24 May 2010
        Has the greenhouse effect been falsified?
        #52 Riccardo at 04:05 AM on 24 May, 2010 could you be so kind to provide the figure captions Unfortunately I don't have the book itself, just web references (publisher's site). There are some excerpts from first edition along with all the figures. But Fig 8.3 a-c is rather self explanatory. The effect of really low specific humidity can be seen at the low frequency end of Fig 8.3 b (Antarctica). I think Fig 8.2 (Barrow, Alaska) shown as Fig 1 in the post does not have extreme low humidity after all. Fig 1 a (20 km looking down) may lack vapor fingerprint below 600 cm^-1, but Fig 1 b (surface looking up) has it. With really low vapor contents it would be a partial see-through in this frequency range to 2.7 K space above (as it is at the Antarctic ice sheet during winter). On top of that the rather high surface temperature (268 K) indicates the shot was not made in winter. Also, note how CO₂ has a cooling effect in Antarctic winter and to a lesser extent for deep convective cloud tops at the Tropics (Fig 8.3 c, lower graph). It is worth considering the highly variable contribution from water vapor as well, even if none of the graphs shows anything below 400 cm^-1 in spite of the significant (wet) action happening there.
118814. Doug Bostrom at 05:46 AM on 24 May 2010
        Robust warming of the global upper ocean
        RSVP while sadly I do not have the skill or background necessary to provide a proper answer, I imagine that if the upper ocean is unable to convey heat to the lower ocean with sufficient speed, the upper ocean will indeed become less effective at mopping up heat from the atmosphere, so we could then expect to see the atmosphere begin to warm more rapidly. Veering off into complete speculation, this is sort of consistent with what we see and even fits with Berényi's assertion that the ocean is taking up less heat of late. But I don't really know enough about what I'm talking about, so take it with a salt dome.
118815. Doug Bostrom at 05:35 AM on 24 May 2010
        Robust warming of the global upper ocean
        Berényi I hear what you're saying about XBT versus ARGO data but I have to say I find it hard to imagine that the total (and rather astoundingly large) difference in heat content between the left and right end of the graph is all down to instrumentation error. That would imply that the instrumentation is entirely worthless, which I believe would be a fairly controversial assertion and probably very hard to defend in detail.
118816. gp2 at 05:10 AM on 24 May 2010
        Robust warming of the global upper ocean
        According to Lyman et al. 2010 clearly there is no OHC decrease in the last 6 years, trenberth paper is available here.
118817. Riccardo at 04:57 AM on 24 May 2010
        Robust warming of the global upper ocean
        Jeff T, the red line is the trend from 1993 while the comparison with the Argo 0-2000 data (blu line, 0.54 W/m2) has to be made starting from 2003, in which case the trend is down to about 0.23 W/m2.
118818. Eric (skeptic) at 04:50 AM on 24 May 2010
        Volcanoes emit more CO2 than humans
        It is useful to compare the volcano in iceland and its 150-300 ktons per day to the EU cuts. According to this article, http://europa.eu/rapid/pressReleasesAction.do?reference=IP/09/794 the EU cut about 174 ktons per day in 2008. The Icelandic volcano emits about 150-300 ktons per day, a comparable amount. Of course the volcano will stop emitting at some point, but for now it is a valid skeptical talking point to say that the volcano undoes the EU cuts.
118819. Jeff T at 04:24 AM on 24 May 2010
        Robust warming of the global upper ocean
        This statement near the end of the post confuses me, "Note that the blue trend is greater than the black line over the same period. This means that more heat is accumulating at greater depths than 700 metres." The deep data (blue line in Figure 3) have a SMALLER slope than the shallow data (red). It's the slope that matters, isn't it?
118820. Mal Adapted at 04:21 AM on 24 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        Si:

        Again why the ad hom attacks? (and yes I do lack the simple comprehension why some regular posters on this site sneer and belittle others - it is why I read this blog so seldom)

        Our host has deleted both of our most recent comments, no doubt because they violated the comments policy -- sorry John, I'll be more careful. Your reaction to perceived attacks is further evidence that you're not acquainted with how science is actually done. In the community of scientific peers, debate can be pretty rough-and-tumble, and that's a good thing. This piece (h/t Hank Roberts) by a former member of that community lays it out succinctly:

        Science doesn’t work despite scientists being asses. Science works, to at least some extent, because scientists are asses. Bickering and backstabbing are essential elements of the process.

        The point of my original comment is that if you want to challenge the AGW consensus, you need to follow the same long, arduous process as the scientists who contributed to it. There are easier ways to make a living, believe me. I don't think it's beyond your abilities, but until you've covered all the ground the experts have, your sense of your own competence is illusory. That's not an attack, that's just sincere advice.
118821. Riccardo at 04:05 AM on 24 May 2010
        Has the greenhouse effect been falsified?
        Berényi Péter, could you be so kind to provide the figure captions or give the details yourself?
118822. e at 03:46 AM on 24 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        RSVP, I think your point was addressed in the course of discussion, though perhaps not directly. Nobody here is claiming that this single data point proves or disproves global warming. It is just another data point consistent with the so-called "hockey team" global reconstructions. It is the summation of this data point and many many others that makes the case for global warming, not any one data point on its own. The point is not that local conditions should be ignored, but that they must weighed in summation with other local conditions across the globe.
118823. RSVP at 03:03 AM on 24 May 2010
        Robust warming of the global upper ocean
        As oceans warm over time, for the "same" air temperature, oceans should warm less as per convective heat transfer law. Would this not constitute negative feedback?
118824. RSVP at 02:58 AM on 24 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        sorry, not Artic, Antartic
118825. RSVP at 02:57 AM on 24 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        chris. you say, "The observation is that the Lake Tanganyika surface has warmed very considerably especially in the last 50 years, and is likely warmer than it has been for 1500 years. The warming of the last 50 years has been directly measured and is in line with the wider understanding of enhanced greenhouse-induced warming both locally and more widely." I asked a fair question in an earlier post relative to what you are stating here in point six. That is, why does it seem appropriate to make a case for global warming about a geographically localized condition? By the way, the question is not directed necessarily to you. It is actually rhetorical in that it refers to what I thought was rule number one around here, not to use local conditions to make a case about global warming. In fact, just the opposite was true when it was pointed out that there were surface waters in the Artic that were actually cooler, this data being discounted as actually proof of global warming for other convoluted reasons. I would add that where I made the comment earlier, it was done in tandem with another remark, and as I have found many times in the past, those that take up points with me typically choose what appears to be the easier issue almost as if to tactically distract readers from what might be embarrassing or controversion.
118826. Albatross at 02:38 AM on 24 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        Chris @152, "It's simply impossible to discuss straightforward issues of science with individuals that use ignorance as a debating point, adopt a null hypothesis that everything they think of that might be a problem is a problem, and consider that the point of reading a scientific paper is to attempt to trash it (by misrepresentation if necessary)." I would second that, especially the last portion of the sentence. You really did hit the nail on the head there. As for the rest of your post. Thanks. Thanks too for bringing the thread back on track again-- you make some excellent points. Si @154, two words "cumulative impacts". And please don't spam this thread by desperately throwing out there every contrarian speaking point which has long been debunked.
118827. Berényi Péter at 02:16 AM on 24 May 2010
        Has the greenhouse effect been falsified?
        #50 sylas at 02:23 AM on 23 May, 2010 please be assured that I am not deliberately distorting things I have never told you would do such a thing, not even thought about it. If it gave an impression like that I am sorry. Figure 1 comes from a textbook (it is Fig 8.2 there). A First Course In Atmospheric Radiation (2nd Ed.) By Grant W. Petty 460 pp. (paperback) Sundog Publishing, Madison, Wisconsin Publication Date: March 2006 ISBN-10: 0-9729033-1-3 ISBN-13: 978-0-9729033-1-8 Unfortunately we have seen more than one error in textbooks. Of course the arctic air could be extremely dry then and there. We may never know since neither date & exact location of measurement is specified, nor arctic window (long wave, low wave number) frequencies are included in the upwelling IR graph. Otherwise the sheer mass of air above sea level also absorbs some window radiation. Anyway, it is always better to understand in detail what you see than not to. Fig 8.3 a-b-c-d of the same book are also enlightening.
118828. chris at 01:48 AM on 24 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        Oh well, this illustrates why science pseudoskeptics organise their own climate "conference" and real scientists don't go. It's simply impossible to discuss straightforward issues of science with individuals that use ignorance as a debating point, adopt a null hypothesis that everything they think of that might be a problem is a problem, and consider that the point of reading a scientific paper is to attempt to trash it (by misrepresentation if necessary). Relating to some of the stuff that’s been thrown at the paper on this thread, it isn't difficult for a non-expert to quite easily establish the following: ONE: the paper isn't about sardines. "Primary productivity" refers to productivity at the bottom of the food chain and in marine/lake environments usually relates to the photosynthetic fixing of CO2 which is the primary source of biological productivity at all levels of the food chain. In other words assessment of primary productivity in oceans and lakes usually relates to algae. It doesn't mean sardines! TWO: Despite assertions that the proxy temperature record isn't calibrated against the lakes surface temperature, in fact the proxy data that overlaps (top of the core) contemporary direct measurements were cross correlated with direct lake surface temperatures (at Kayla and Mpulunga; see Figure 2 of Tierney et al, 2010). In addition the temperature proxy was calibrated with a large amount of additional data that relates lake surface temperatures to the TEX proxy temperatures (see Supplement of Tierney et al, 2010). Even if the top of the TEX data wasn't extensively calibrated (it was) or the core proxy temperatures matched with direct lake surface temperatures (it was) the interpretation that current lake temperatures are the warmest in 1500 years is independent of any uncertainties in calibrations, or offsets relative to current temperatures. THREE: Hydrothermal vents. Skepticstudent linked to a paper about hydrothermal vents in lake Tanganyika but failed to do the obvious assessment of whether these were near the coring site. Hydrothermal vents are found in the Uvira fault region at or near the N end of the lake (in the waters near Pemba and Cape Banza). Inspection of a map indicates that these are 300 km or more from the coring site. FOUR: Hydrothermal vents. Significant warming from hydrothermal vents would yield a distinctive pattern of warming in the water column. Sampling of the water column and multiple sites throughout the lake indicates that there is no significant contribution from bottom warming and that the thermal pattern of water column is as expected from surface warming. FIVE: non-representativeness of a single core. Similar arguments apply to Antarctic cores. Single cores give data that are representative of particular spatial regime as long as an appropriate proxy is used. Thus a single core can give good insight into CO2 levels worldwide since CO2 levels are well averaged globally on the timescales of core resolution. Temperature proxies also give good representation of a wider spatial extent since it is well known that temporally-averaged temperature variations are correlated across significant distances (up to 1200 km). In this particular case (Tierney et al, 2010) analysis of lake surface temperatures and temperature profies through the water column indicate that single sites within Lake Tanganyika are likely to be more widely representative (see Figure just above). SIX: The warming not due to man-made global warming. Since the site chosen for coring was in an isolated area with little human population, little deforestation or agriculture (which could impact on nutrient loading by runoff), there is little evidence that local direct human impacts affect the analyses. The observation is that the Lake Tanganyika surface has warmed very considerably especially in the last 50 years, and is likely warmer than it has been for 1500 years. The warming of the last 50 years has been directly measured and is in line with the wider understanding of enhanced greenhouse-induced warming both locally and more widely. The attribution of the warming to anthropogenic global warming is a pretty reasonable one in the context of what we know. SEVEN: General point. This paper seems like a pretty good analysis of paleoproxies for lake surface temperatures, primary productivity (and charcoal deposition as a proxy for local forest fires). However (and with greatest respect to Dr. Tierney and her coauthors) its interpretations and conclusions are a small input to our broad understanding of the Earth response to human enhancement of the grrenhouse effect. It really isn't worth a frenzy of attempted trashing!
118829. Riccardo at 01:43 AM on 24 May 2010
        Robust warming of the global upper ocean
        Berényi Péter, "It is only the last 6 years when OHC in the upper 700 m of oceans is measured properly. It is decreasing" Apparently not.
118830. Berényi Péter at 00:39 AM on 24 May 2010
        Robust warming of the global upper ocean
        #4 Marcel Bökstedt at 21:32 PM on 23 May, 2010 Is there a reason for that the uncertainty due to choice of correction is small in the beginning and the end of the period (around 1996 and 2006), and bigger in the middle (around 2000) - that looks strange to me? Yes. Instrumentation has changed a lot in this time interval. There is also a gap between 1996 and 2002 when old (MBT/XBT) systems were all but abandoned and ARGO was not deployed en masse yet. The huge and abrupt increase in OHC at the end of this period must be an artifact due to intercalibration problems and lack of data. It is also inconsistent with satellite radiation budget measurements. It is only the last 6 years when OHC in the upper 700 m of oceans is measured properly. It is decreasing. Below that level even recent data are unreliable, because ARGO floats in the tropics initially have not worked according to design. The guys didn't dare to let them go down to 2000 m for they would never come back to the surface in waters warm enough.
118831. Marcel Bökstedt at 22:37 PM on 23 May 2010
        Robust warming of the global upper ocean
        Bérenyi Péter> The papers in question here discuss the trend in ocean heat content up to 2008. As far as I can see, the corrections you mention cannot have much influence on this.
118832. Marcel Bökstedt at 21:32 PM on 23 May 2010
        Robust warming of the global upper ocean
        These papers are clearly important, but not so easy to read for a non-expert like me. I'll try to state what I get out of the Lyman paper, in the hope that someone can correct my misunderstanings. First a very very stupid question, but google did not help me, and maybe I'm not the only one who does not know: What precisely does the technical term "climatology" mean in contexts like "We estimate climatological uncertainties (Fig. 3, magenta line) arising from Argo versus pre-Argo sampling from pairs of curves using the same mapping routine and XBT corrections but different baseline climatologies (Fig. 2, solid vs. dashed lines)." But more importantly, what exactly are Lyman et al doing? They trust data from the new Argo floats, so that the main problem they want to adress is how to interpret the older data from the XBT sinking devices. There has been a number of attempts to translate these data into ocean heat content data. These attempts don't agree with each other (fig 1 above), and the paper is trying to reconcile the attempts. According to this study, we can break up the differences between the different published ocean heat content reconstructions into several components. I believe that the main argument is that by analysing the uncertainty in each of these component individually and adding, the uncertainty in the total ocean heat content estimate gets smaller. The main components are: Differences in XBT data sets, differences in climatology, differences in method of XBT bias corrections. The first step is to recompute the published estimates for ocean heat content, using the published algorithms for bias correction, but using the same standard dataset or the same standard climatology (which at least means choosing the same period for computing the temperature baseline, but presumably more than this). In figure 2 above, the results are compared to the original estimates, and to each other. The green line corresponds to one method of bias correction as originally published, the green dotted line to the same bias correction but with the standard climatology, the green dotted line again with the same bias correction, but with the standard raw dataset. Using the same dataset or the same climatology brings the curves closer, but they are still far from identical. The end result is that the biggest uncertainty in the estimate of ocean heat content comes from the choice of method for bias correction. I believe that they consider the published methods as having equal value, and compute a mean and standard deviation from the set of these methods. This mean is then the basis for their estimate of ocean heat content. A few points I don't understand: What is the uncertainty due to "mapping"? Is there a reason for that the uncertainty due to choice of correction is small in the beginning and the end of the period (around 1996 and 2006), and bigger in the middle (around 2000) - that looks strange to me?
118833. Mythago at 21:09 PM on 23 May 2010
        The significance of the CO2 lag
        Many thanks to 'Ned' and Michael Sweet for answering my question about the CO2 relationship between the atmosphere and the ocean. I now understand. Simple answer that I should have known was 'equilibrium' or 'establishing a balance' between the ocean and the atmosphere, (to put it another way). Thanks gents for the assistance. Very useful explanation and one I can understand easily.
118834. Berényi Péter at 20:24 PM on 23 May 2010
        Robust warming of the global upper ocean
        #2 tobyjoyce at 17:57 PM on 23 May, 2010 The link to Lyman(2010) needs to be fixed It must be this one: Letter Nature 465, 334-337 (20 May 2010) | doi:10.1038/nature09043; Received 8 December 2009; Accepted 22 March 2010 Robust warming of the global upper ocean John M. Lyman, Simon A. Good, Viktor V. Gouretski, Masayoshi Ishii, Gregory C. Johnson, Matthew D. Palmer, Doug M. Smith & Josh K. Willis However, before delving into the question deeper I would like to know the actual reason behind the downward modification of OHC trend for the last couple of years at NODC occuring on Wed, 20-Jan-2010 22:14 UTC. It is undocumented.
118835. RSVP at 19:36 PM on 23 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        Albatros quotes: "...But there is no evidence for increased deepwater volcanic activity in the lake in the 20th century. In 1971, a survey team found that the rate of geothermal heat flux in Tanganyika was 0.04 watts per meters squared, close to the global average (Degens et al., 1971, Naturwissenschaften). ..." If volcanic activity is perfectly constant, but the lake level decreases, the temperature just might be affected after a while. Now the difficulty arises... is this due to the volcanic activity, global warming or maybe just a local climate change?
118836. Riccardo at 19:23 PM on 23 May 2010
        It's the sun
        Friend, the microwave power emitted by the sun is many orders of magnitude lower the the IR or visible emission. I'd not expect any significant effect.
118837. Riccardo at 19:19 PM on 23 May 2010
        Arctic sea ice has recovered
        Erik, fig. 2 above is not a forecast but a model calculation of ice volume, where the measured relevant parameters are fed in. Section 2 of the paper describes the model, the first paragraph of section 3 describe how they use it in forecast mode.
118838. Si at 18:55 PM on 23 May 2010
        There is no consensus
        Doug, it is a plea for more funding. "It calls for a new era of climate change science where an emphasis is placed on "fundamental, use-inspired" research,"
118839. tobyjoyce at 17:57 PM on 23 May 2010
        Robust warming of the global upper ocean
        P.s. The link to Lyman(2010) needs to be fixed!
        Response: Fixed, thanks for pointing that out.
118840. tobyjoyce at 17:55 PM on 23 May 2010
        Robust warming of the global upper ocean
        I would like just to check the meaning of the word "robust" in this context. In statistics, a "robust estimate" is one that is not affected by small departures from model assumptions. Does the phrase "robust warming trend" have the same meaning here?
118841. mike at 17:51 PM on 23 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        63 johnd at 08:34 AM on 22 May, 2010 "Whether taking simple surface sediment cores or cores from deep below in the search for natural resources, there is a strict regime on what is required to satisfy firstly those who will decide whether to proceed further or not, and an even tighter requirement for it to become part of a bankable feasibility study, and then even tighter beyond that." johnd- As a research geologist with some small amount of experience in mineral exploration, I think your criticisms are off base. In the world of publicly-funded science, "those who will decide whether to proceed further or not" and for work to "become part of a bankable feasibility study" are the peer reviewers of the journal where the work is published. The fact that Dr Tierney's paper appears in Nature Geoscience - a very prestigious journal with a low acceptance rate - means that your quality-control concerns would have been met more than adequately in the review process. Your continued questioning in this regard is as inappropriate as would mine be of your professional work. The difference of course is that your proprietary output is protected from comment by the ignorant whereas the work of those who publish in the peer-reviewed literature is available to all to pick over.
118842. Phila at 17:25 PM on 23 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        #120 Frogstar "As a (skeptical) scientist, I am here because the topics under discussion are being used in a semi-technical geopolitical debate that involves subjects very dear to my heart (life, death, money, taxes, etc)." The policy implications are well worth discussing and there's plenty of room for honest disagreement. It's a serious subject, and ideally, we'd all be having an serious conversation about it. Unfortunately, that discussion is largely being postponed so that we can argue over whether CO2 is actually a greenhouse gas, whether Jessica Tierney actually knows how to conduct research, or what have you. "The kinetics in that lab taught me a lot about waiting to see if measurements bore out predictions and, when they didn't, it was a learning opportunity." That's a reasonable approach in many situations. This situation is a bit trickier, obviously, because the prognosis gets worse as we wait and there are no do-overs, as far as we know. The better analogy here would be to medicine: With some conditions, you can wait for measurements to bear out predictions. With others, doing so would be...well, let's just say "unwise."
118843. Doug Bostrom at 16:40 PM on 23 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        Presumably frogster is referring to such serious and enlightening remarks from so-called skeptics as: One tree does not a hockey stick make ;-) or LOL. Has anyone happened to notice that this study is basically about fishing for sardines? Regarding speaking to truckers, frogster, I think it would not be too difficult to show how Willis' critique of Tierney's paper is not aimed at the side of the correct barn. "Your oil pressure gauge is wrong, you know that it reads 50psi when it really is measuring 60psi. If the reading on the gauge drops to 40psi you know you've got a loss of oil pressure, even if you know the reading is 'wrong'." Not complicated.
118844. Albatross at 16:21 PM on 23 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        thefrogstar @120 "climate science thought it could 'run with the big boys' yet still go on 'providing weather forecasts'." There is so much wrong that statement-- I'm not sure whether your erroneous comparsion with weather forecasts was intentional or not. Anyhow, I'll leave it there. As for your claim about some of the points being raised by contrians here being "valid". I strongly disagree, and that is exactly why I and others are getting frustrated. Do you not see how arrogant and rude it is by some here to presume to know more than the people (e.g., Dr. Tierney and her colleagues) who have worked so hard on this, those who have researched the topic at hand (i.e., literature review), wrote the proposal, invested the time and effort to collect the data, processed it, analysed it, checked the numbers, written it up, gone through several iterations, and then finally gone through peer review (a very humbling and exhausting experience in most cases), only to have some people posting on an internet blog (who are not even qualified or experienced in the field and who have not taken the time and effort to understand the problem in the first place)cavalierly dismiss it as sardine research. And worse yet, doing so not using rational and informed scientific critique and methods, but essentially taking cheap shots. I sense no inclination whatsoever from certain contrarians to learn form this paper, or other climate papers, or to concede when they have been shown to be wrong. Does that not tell you something or concern you? Moreover, most of the criticisms raised here have been addressed by the authors, and people who have published on the subject prior to this study (this study does not stand in isolation, it is part of a much bigger picture of scientific understanding), yet the contrarians it seems could not be bothered to first do the leg work to determine whether or not their "concerns" had been addressed before making condescending remarks. This has happened repeatedly in recent years in the field of climate science and related disciplines, and to be candid, it is getting incredibly tiresome. I'll agree with you that the IPCC has done a relatively poor job at communicating the science. That said, they are, believe it or not, reliant on the volunteer work of hundreds of scientists and have very few full time staff. They do not have a well-oiled, experienced and politically savvy PR team. Anyhow, let us hope that they are provided the means required to communicate the science and the gravity of this situation in AR5. And frogstar, the hubris I am seeing (on an increasing scale) is coming from the contrarians and "skeptics". I am pretty highly qualified in my field, but I don't not presume to know more, or feel inclined to be contrary or question the science of an oncologist, for example. Additionally, I acccept that they are highly trained, experienced and professional, and that it would be incredibly arrogant and disrespectful (paranoid even?) of me to feel obligated to openly question their work simply because they were the bearer of bad news or news that their findings did not sit well with me. And, in the event I did elect to attack or question their research after Googling for a few days, I would not be offended (or surprised) if they set me straight, were rather snarky or accused me of hubris even if I do happen to have post graduate degree/s in another unrelated field.
118845. thefrogstar at 15:20 PM on 23 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        Phila #118, The science on these threads can, and will, progress, irrespective of whether skeptics arguments turn out to be correct or not. As a (skeptical) scientist, I am here because the topics under discussion are being used in a semi-technical geopolitical debate that involves subjects very dear to my heart (life, death, money, taxes, etc). That's inevitably going to bring more scrutiny, from people at all levels of scientific education and competence. Yes, it's uncomfortable. My adviser used to tell us (his research group) that if we "couldn't explain what we did, and why it was important, to a truck driver in a honky-tonk bar in Texas, and why they should be paying for it", then we should ask ourselves some serious questions. Frankly, what I read on this particular thread, is a bunch of people being quite rude and disparaging towards (a few) other people who are clearly scientifically competent and seem to be raising valid points. That approach is not going to get very far with the truck drivers. Without being (too) rude, I sometimes wonder if climate science thought it could 'run with the big boys' yet still go on 'providing weather forecasts'. Another thing my supervisor told us is "that we're a kinetics lab". The kinetics in that lab taught me a lot about waiting to see if measurements bore out predictions and, when they didn't, it was a learning opportunity. Unfortunately climate science doesn't work on the same time scale as most other sciences, and the hubris seems to be commensurately greater.
118846. Friend at 12:55 PM on 23 May 2010
        It's the sun
        Isn't it possible that the Sun is causing an increase in temperature of the core of the earth by way of radiation that passes harmlessly through the atmosphere and crust much like a microwave oven? Or is this just impossible? thanks
118847. Doug Bostrom at 12:17 PM on 23 May 2010
        Climate's changed before
        Roger, what's to discuss? The National Academy of Sciences says anthropogenic warming is a fact, you say it's not and you're quite unprepared to accept otherwise. I'm a bystander to your argument with the NAS but I have to say, I attach more weight to their conclusion and not yours. Are you surprised, that I'd have to give more credit to the NAS and their conclusion based on a veritable mountain of evidence, as opposed to your personal opinion supported by a Youtube video? What an extraordinary conversation. I've participated in many such yet they still leave my head spinning. Either one must leave the merry-go-round filled with folks who show every sign of technical psychosis or one must jump on and join the endless revolution of repetitions.
118848. Rogerthesurf at 11:50 AM on 23 May 2010
        Climate's changed before
        Doug, Have done, However I expect you to use your brain to discuss my point. I dont give two hoots what the NAS says, unless they can show me how the "Anthropogenic CO2 causes Global Warming" hypothesis is proven. Now that would be not unreasonable to expect from a bunch of scientists right? And it might be news to you but "anthropogenic warming" is not considered to be fact, even in IPCC reports and there is an increasing body of opinion that support what I am questioning. But most importantly, lets not forget this conversation is about whether this blog addresses the question "What does past climate change tell us about global warming?" and I am maintaining that it skirts around the real issue which is what I am raising here. Cheers Roger
118849. Doug Bostrom at 11:30 AM on 23 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        You're of course entitled to your opinion that the paper under discussion here is "primarily about sardine production" when sardines are not mentioned in the title. I'm uncomfortably prepared to concede that the paper would possibly have been better focused if it had confined itself to paleotemperature reconstruction but technically speaking I don't have the background to say that. For my part-- concerned as I am with climate change-- the significance of the paper lies in what its title says. Probably needless to say, but the reason I found my way here was because of climate problems, not a shortage of sardines. At the end of the day, your argument still consists of "I doubt it." But there's no such thing as a last word in a venue such as this so I'm going to ignore what you have to say next about this unless you veer off in some other direction.
118850. Phila at 11:23 AM on 23 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        #101 "e and Phila, 94 and 95. I think there are rather more skeptical climate scientists than you realise. - Spencer, Michaels, Christy" Yes, there are some skeptical climate scientists out there, and they've been making their views known for years, as they should. I fail to see what this has to do with people who lack any relevant expertise casually accusing working scientists of not understanding their own fields. How does such behavior make science "more robust"? More to the point, how could science ever progress if it were obliged to cater to that odd combination of arrogance and ignorance? Look, I'd love to revolutionize evolutionary biology, or any other field...but realistically, what are the chances I'm going to do that without educating myself to at least the level of a grad student, not just in the subject itself but also in the nuts and bolts of scientific practice and discourse? The skeptical scientists you've named have so far failed to convince very many of their colleagues that they're right and everyone else is wrong. But they do have credentials and they've more or less followed the rules of the game. As such, their contributions are valuable even if they're incorrect. But too many amateur "skeptical" arguments -- including some of the ones on this thread -- fall under the category of "not even wrong." We agree that it's healthy to have people get more interested in and involved with science. But we seem to disagree about the amount of time, effort, and humility it takes to get good at it. As I see it, no one deserves an 'A' just for showing up.

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