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Comments 118851 to 118900:

118851. e at 13:47 PM on 24 May 2010
        Climate's changed before
        Roger > "Are you telling me you can do this for previous warm periods (when there was no anthropogenic CO2) as well and get an intelligible result?" Yes! You seem to be under the misconception that current theories of climate include only CO2 and nothing else. This is not the case. As scaddenp pointed out, current theories of climate take into account all known forcings, not just GHG's. As for how we can have warming in the past when CO2 is low, and warming now that can be attributed to CO2, imagine a room with two heaters: Let's call them heater 1 and heater 2 (since I'm not very creative). Now let's say I told you that if I turn up heater 2 without changing heater 1, the temperature in the room will increase. Hopefully it is pretty self-evident that this is true. What you are arguing is that the room was warmer in the past, and heater 2 was set low, therefore heater 2 could not possibly have a warming affect on the room. I hope you can see the mistake in that line of thought. Clearly, it is possible that heater 1 was set high at a time when heater 2 was stable, thus leading to warmer temperatures in the past. This does not preclude the fact that heater 2 can have a warming effect right now. In this analogy, think of heater 2 as greenhouse gasses and heater 1 as solar irradiance (or any other non-GHG forcing). When the earth was warmer in the past while CO2 was low, other forcings were responsible for the warming (such as the earth being generally closer to the sun due to cyclical changes in our orbit). Scientists know this because they can reconstruct the historical levels of forcings and global temperatures, and analyse the relationships between the two. What they conclude is that man-made CO2 was the primary driver of warming in the past 30 years. This is reason why past climate change acts as evidence for AGW, which is the point of this post. One final note: dozens of climate models have been developed that can accurately recreate both past and present temperature trends. Out of all these, none have been able to recreate real world temperature trends without confirming that CO2 was the primary driver of warming in the past 30 years. Is this all just a coincidence?
118852. From Peru at 13:38 PM on 24 May 2010
        Robust warming of the global upper ocean
        One curious fact: in figure 1, there is a considerable divergence between the datasets after 2003. In figure 2, they seem to converge as they approach present time (roughly 2009). What is the reason?
118853. Doug Bostrom at 11:31 AM on 24 May 2010
        Climate's changed before
        Roger, off-topic but I've visited your archive of failed conversations and find it quite interesting. You refer to it as "My Other Blog where I record conversations that Global Warming Protagonists put in the "too hard basket", an ironically accurate description from my perspective. It is indeed too hard, impossible really to have a productive conversation when one's conversational partner refuses to address evidence that is accepted by what is arguably one of the premier scientific bodies as uncontroversial. You say of the NAS report I mention earlier "...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? I'd suggest that as you are the person making an assertion that flies in the face of facts, the onus is on you to provide a detailed rebuttal to the NAS report. You should do so in a way leading a reasonable person to conclude that "a bunch of scientists" practicing in domains directly related to climate science as opposed to economics are lacking in the insight necessary to conclude as they do that "Some scientific conclusions or theories have been so thoroughly examined and tested, and supported by so many independent observations and results, that their likelihood of subsequently being found to be wrong is vanishingly small. Such conclusions and theories are then regarded as settled facts. This is the case for the conclusions that the Earth system is warming and that much of this warming is very likely due to human activities." Failing that, I'd say you've invited yourself into another conversation that is "too hard", too hard for you. But perhaps raw pugilism without hope of victory is your main objective. I can't say.
118854. Rogerthesurf at 10:35 AM on 24 May 2010
        Climate's changed before
        Response, Yes expecting a reply to Comment 82. Rather do it on this forum if thats OK Cheers Roger
118855. sylas at 10:03 AM on 24 May 2010
        Has the greenhouse effect been falsified?
        Hi Berényi Péter; thanks -- sorry if I was over sensitive. I am reassured and happy to continue to explain what is necessary for your concerns, and to keep fixing any errors I have allowed into the essay! The main thing I can do at this point is assure you that the plot in the Figure is one is of real measurements, unscaled; and there's nothing particularly unexceptional about them. The IR transmittance for those observations is clearly well over 80%, as you note, but this is not unusual. It is not a global average, but a nice clear sample for comparing up and down fluxes in the Arctic. Essays and textbooks can indeed have errors, as we've seen in my writing here as well! But the specifics of the figure here are not an error. You've got a nice open IR window there. Other spectra will show other characteristics of the conditions at other times and places, and this is indeed very interesting -- but I don't understand the point. They ALL show the greenhouse effect at work, and there's nothing to cast the slightest doubt on the figure I used. Dave Tobin is a busy working scientist and I appreciate his willingness to help out with this essay, but I don't want to overload him with questions when the basic fundamentals here are pretty straightforward. He has said to me unambiguously that there are real measurements, from real instruments, and that it is not uncommon to have > 80% transmission in the 10 micron window. He also points out that "we" (the various scientists involved in this work on remote sensing) have spent many careers worth of time on improving and verifying the accuracy of the measurements. The best reference for more about how this is done is a paper cited for this essay, Tobin et al 2006, which shows up in the copy under the "list of arguments" here. Follow this link: Has the greenhouse effect been falsified. Transcribing the reference to here for now, it is: Tobin, D. C., et al. (2006) Radiometric and spectral validation of Atmospheric Infrared Sounder observations with the aircraft-based Scanning High-Resolution Interferometer Sounder, in J. Geophys. Res., Vol 111, D09S02. This describes validation of atmospheric emission measurements from space, using high altitude aircraft measurements. Similar measurements obtained the upwards emission spectrum shown in figure 1. Unfortunately, the "footnote" sections on further reading and acknowledgments didn't appear here on the blog; I'll see about having them added to this blog post, maybe. I don't know what you mean about a cooling effect. There is a cooling effect in the upper atmosphere, certainly, but at the surface? I don't think so. If you really want to dig into fine details you are better to go to the scientific literature rather than this first level introduction essay. But nothing whatsoever in the details does anything to "falsify" the greenhouse effect! I recommend the references and further reading sections of the main entry as a starting point for people wanting more on the physical details.
118856. Doug Bostrom at 09:56 AM on 24 May 2010
        Robust warming of the global upper ocean
        Berényi, going from the micro and back to the macro view, do you think the graph you reproduce here should be taken as indicating no heating of the ocean? My point is, I see a lot of up-down on the scale you reproduced here but when we look at a longer interval those wiggles are overwhelmed by what looks to the untrained eye as an enormous uptake of heat. What's your conclusion? Is the entire instrumental we have completely unreliable to the point that even the little bit of data you present is meaningless? If it is meaningless, why are you using it and how can you conclude that there is a decrease in OHC in the period you show?
118857. scaddenp at 09:46 AM on 24 May 2010
        Climate's changed before
        "Are you telling me you can do this for previous warm periods (when there was no anthropogenic CO2) as well and get an intelligible result?" Yes. See the paleoclimate chapter 6, IPCC WG1 for graphs and references to papers that do this. Not one effort but many. As stated earlier, our theory of climate involves solar, aerosol, and albedo as well as GHG. Did you not look at the Benestad & Schmidt paper I referenced above? As for video - what the? This problem is the everyday reality for every scientist - that the value of peer review and why you want the person most likely to be upset by your findings to review them. We certainly see alternative hypotheses published - they just dont stand up to scrutiny.
118858. johnd at 09:45 AM on 24 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        Marcus at 09:28 AM, of course it occurs all the time. My post wasn't examining the splicing of the core data itself, but examining if the same scrutiny was being applied to it as had been applied to other such instances as the temperature data you referred to with the Briffa tree ring proxy temperature reconstruction springing to mind.
118859. Berényi Péter at 09:45 AM on 24 May 2010
        Robust warming of the global upper ocean
        #14 hadfield at 08:27 AM on 24 May, 2010 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 Here is a magnified version of the last 6 years from NODC Ocean Climate Lab OHC graph. It is clearly decreasing somewhat. On the other hand if recent globally averaged energy imbalance at TOA is +0.54 Wm^-2 as claimed, in six years OHC should have increased by 5×10²² Joules. It is not seen. As OHC is not measured properly in depths greater than 700 m while above it accuracy and precision has improved tremendously after 2003 due to ARGO, one has to invent a hypothetical process capable to push that much heat below the line without even touching the upper layer. I have not seen a reasonable explanation yet. If you know one, put it forward please. Until that time Trenberth's travesty is well and alive. BTW, the NODC Ocean Climate Lab has no explanation for the recent downward adjustment at their website. All they have is Levitus 2009 but of course it has nothing to say about something done in this January.
118860. Marcus at 09:43 AM on 24 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        So further to my above post, johnd. If the data was obtained from the same site-& if the values of measurement used the same scale (either in meters or degrees C-or both) then there is absolutely nothing wrong with splicing the data. By contrast, McLean spliced weather balloon data (which was based off a 1961-1990 average) with satellite data (which was based off a 1979-2000 average), without acknowledging he'd done so, & without adjusting the scale of either data set. Because the satellite data contained a smaller anomaly (because average temperatures are warmer) it makes it look like temperatures level off around the 1970's to 1980's. This helped make the correlation between temperature & the Ocean Oscillation Index look much stronger than it really was. So you see it was how he handled the data-post splicing-which earned him brickbats, not the act of splicing itself. For a more enlightening analysis, check Here
118861. Doug Bostrom at 09:42 AM on 24 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        Johnd, I especially like the "How about we just leave it" part, no further action required. :-)
118862. johnd at 09:38 AM on 24 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        How about we just leave it to the authors of the study whom both Chris and Doug may consider contacting, or John Cook, who posted the lead post, to clarify what were the primary questions being asked that the study hoped to answer rather than second guessing evryone.
118863. Marcus at 09:28 AM on 24 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        Johnd @ 133. On the issue of splicing data-it's not as big a deal as you might think, it occurs all the time. As long as the splicing makes sense, & as long as the spliced data fits the same Y-axis (or uses an appropriately labeled 2nd Y-axis) then its not really a big issue. Why the splicing in the McLean paper is so controversial is (a) it didn't make real sense (why use a mix of weather balloon & satellite data, when he could have used just a continuous weather balloon record) & (b) the data used completely different Y-axis scales, but he failed to adjust either of the data sets to make the scales match. This led to a situation where the temperature graph has a significantly smaller incline than if it had been properly scaled. He also failed to acknowledge either the splice or the difference in scales to his readers. McLean then made correlations based on this incorrectly spliced graph. Now, if you can show that the splicing of data by Tierney, that you're referring to, has been done in a way that has resulted in the same kind of erroneous final product seen in McLean's paper, then please be so kind as to point it out-otherwise, as others have noted here, you're really grasping at straws.
118864. Rogerthesurf at 09:27 AM on 24 May 2010
        Climate's changed before
        scaddenp, I am awaiting some answer from the owner of this blog, However I will comment on "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 telling me you can do this for previous warm periods (when there was no anthropogenic CO2) as well and get an intelligible result? Did you watch the video and do some thinking then? Cheers Roger
        Response: Sorry, what am I responding to? I must've missed a direct question somewhere but perhaps if you just email me a direct question, I can respond to you directly.
        
118865. chris at 09:19 AM on 24 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        johnd at 08:51 AM on 24 May, 2010 No that's just incorrect johnd; you're being far too defensive. This paper has got nothing to do with "providing further proof of AGW", and it's pretty obvious from my posts that I think no such thing. Perhaps if you relaxed the notion that every single paper has to be either a "proof" or a "disproof" of global warming, you wouldn't need to spend such efforts in attempting to trash the ones you don't like! This paper neither proves nor disproves global warming. What it says is that the warming of Lake Tanganyika in the last 50 years has taken the temperatures to values likely higher than during the last 1500 years. The recent very marked warming really isn't surprising given that oceans and lakes (and land surface and the atmosphere) have risen globally, especially during the last 50 years (see my post just above). Although the paper isn't specifically about global warming it's entirely appropriate to interpret the work in the light of a massive wealth of prior knowledge. After all science isn't a Hermann Hesse-like "Glass Bead Game" where measurements are made but these don't have any meaning. It's entirely appropriate to interpret the data in the light of a vast amount of prior knowledge. But as far as "proving global warming", you're way off the mark. Of course one can say that the data is largely consistent with what we know of contemporary and paleotemperatures both locally and globally, and the causal relationships involved with these...
118866. 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.
        
118867. 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.
118868. 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.
118869. 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.
118870. 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".
118871. 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.
118872. 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.
118873. 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.
118874. 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.
118875. 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.
118876. 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?
118877. 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.
118878. 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.
118879. 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.
118880. 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.
118881. 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.
118882. 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.
118883. 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.
118884. 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?
118885. 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.
118886. 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?
118887. 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.
118888. 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?
118889. RSVP at 02:58 AM on 24 May 2010
        Unprecedented Warming in Lake Tanganyika and its impact on humanity
        sorry, not Artic, Antartic
118890. 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.
118891. 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.
118892. 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.
118893. 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!
118894. 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.
118895. 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.
118896. 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.
118897. 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?
118898. 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.
118899. 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.
118900. 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?

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