Guest Post by Willis Eschenbach
The new Nature Magazine article on Lake Tanganyika, “Late-twentieth-century warming in Lake Tanganyika unprecedented since AD 500”, discussed a couple days ago by Anthony Watts here, was quite interesting to me. In 2003 I had contributed a “Communications Arising” to Nature Magazine regarding earlier claims that AGW was causing productivity loss in the Lake. As a result, I am very familiar with the available records for the lake.
Figure 1. Rainbow over Lake Tanganyika
I was puzzled by the claims in the new article regarding the changes in Lake Tanganyika surface temperatures, because I knew that there was almost no historical data on lake surface temperature. I wondered how they determined the surface temperature of the lake over the past 1,500 years. So I sprung the $18 to purchase the Nature paper and find out …
It turns out that they used a proxy called TEX86, which has been used in other studies. But how did they calibrate the proxy to the lake surface temperature (which they call “LST”)?
Well … they didn’t calibrate it. In their theory, no calibration is needed. However, that seems like a very problematic assumption, as there are always confounding factors for proxies that mean that they need to be calibrated to the instrumental record. Some of these factors are listed in their Supplementary Information.
How well does their reconstruction correspond with air temperatures? Well … rather than compare the reconstruction to local temperatures over the last 50 years, and despite the fact that Lake Tanganyika is in the Southern Hemisphere, they compare the reconstruction to a famous Northern Hemisphere reconstruction …
Figure 2. A most ingenious way to hide the differences between two graphs, by redacting the front information so you can’t see the back information. Note that part (a) uses the discredited Hockeystick and various Hockeystick clones (the so-called “independent reconstructions”) as its basis for comparison.
Commenting on this figure, they say (emphasis mine):
Our LST reconstruction is qualitatively similar to Northern Hemisphere temperature reconstructions (Fig. 3a), implying that Tanganyika LST largely followed global trends in temperature during the past 1,500 years, much as it has in the past half-century. As LST closely tracks air temperatures over the instrumental period, we can also infer that air temperatures in this region of East Africa varied in concert with the global average and thus were controlled primarily by the major forcings influencing temperatures over this timescale, both natural (solar radiation, volcanism) and anthropogenic (greenhouse-gas emissions; refs 19, 20). The temporal resolution of our dataset precludes comparison between Tanganyika LST and volcanic events of the past, but we can compare our record with changes in solar irradiance (total solar irradiance (TSI) anomaly, estimated from 10Be in ice cores21; Fig. 3b). TSI and Tanganyika LST share some similar centennialscale features, including maxima near 1350 and minima at 1450, 1250 and 1000. However, TSI variability clearly does not explain the dramatic twentieth-century increase in LST, which, as with global temperatures, is probably a response to greenhouse-gas forcing.
Unfortunately, in their paper they neglected to show how the Lake Tanganyika LST “closely tracks air temperatures over the instrumental period” of the “past half-century”. To remedy this lacuna, I have plotted the only two longer-term temperature stations on the lake along with the MSU data and the proxy-derived LST:
Figure 3. Ground station temperatures, UAH MSU, and proxy lake surface temperature (LST), 1950-1996
As you can see, while their proxy LST generally agrees with the air temperature over the last half of the record, it does very poorly during the first half. So no, the LST proxy reconstruction does not “closely track air temperatures over the instrumental period.”
Finally, Tierney with some other co-authors have published previously in Science Magazine (subscription required) on the Tanganyika LST. In the current (2010) paper, they say (emphasis mine):
Before the twentieth century, LST varied between 22.5 C and 24.3 C (Fig. 2a). LSTs were relatively warm between ad 500 and 700, followed by an interval of cool LSTs that lasted until ad 1100. Lake Tanganyika then experienced a period of extended warmth between 1100 and 1400, followed by a return to cooler LSTs between 1400 and 1500 and more variable temperatures until 1900. Beginning around 1900, LSTs trend upwards, rising about 2 C in 100 years (see Fig. 2 inset). Our uppermost sample from core MC1 (identified using 210Pb dating as about ad 1996), calibrates to 25.7 C.
OK, so the current paper says that in the last 1,500 years the LST has varied between a low of 22.5 C to a high of 25.7 C. During the last 50 years of the record, their proxy LST value rises by 1.6 C.
And in the current paper, they also say:
Our records indicate that changes in the temperature of Lake Tanganyika in the past few decades exceed previous natural variability.
But in their previous (2008) paper, which used the same TEX86 proxy, they had said:
Holocene lake [Tanganyika] surface temperature (LST) fluctuated between 27° and 29°C …
And during the Holocene, their 2008 paper shows a change of 1.65 C in 50 years, which is larger than the recent change shown in the 2010 paper.
Despite citing the earlier paper in their current paper, they don’t mention these discrepancies … which does make me wonder just how good their proxy is. It also make me curious about what they mean by “previous natural variability”. During the Holocene, by their own figures, the Lake Tanganyika LST was 3 C warmer, and changed temperature faster, than in the last fifty years of their more recent proxy record.
[UPDATE] You know how sometimes you have this nagging feeling that you’ve left something out, and you can’t think of what it was? When I woke up this morning, I realized what I had wanted to say.
This is truly a watershed paper in that it purports to be a study of the changes in lake surface temperature (LST) over time, but they present no measurements of the changes in the LST over time. The only actual surface temperatures mentioned in the paper are the following, all from 2003:
Our uppermost sample from core MC1 (identified using 210Pb dating as about ad 1996), calibrates to 25.7 C. This is within the range of 2003 measurements of seasonal LST for the Kalya Slope area (25.5-26.3 C; see Fig. 2 inset) and is also similar to the annual average LST measured near Mpulungu, at the southern end of the lake (26.1 C; ref. 16).
Unfortunately, reference 16 is very vague. It is:
Descy, J-P. et al. Scientific Support Plan for a Sustainable Development Policy (SPSD II), Part II: Global Change, Ecosystems and Biodiversity Atmosphere and Climate (Belgian Science Policy, 2003).
Research showed this is the Belgian CLIMLAKE project, which I had studied before, and which had some interesting results. Here’s one of them:
Figure 4. Satellite derived lake temperatures. SOURCE – CLIMLAKE FINAL REPORT.
As you can see, on a single day the surface temperature of the lake varies by 4° C from coldest to warmest. I couldn’t find their “2003 measurements of seasonal LST” or their “annual average LST”, although Figure 29 of that CLIMLAKE report does show a three year temperature record for two places on the lake, so I suppose they might have used those.
(As an aside, my high school science teacher would never have allowed such a vague citation as reference 16 above, I’d have gotten a “D” on the paper if not an “F”. “Make it easy to find”, he’d say, “point me right at it. Cite me chapter and verse.” But I digress …)
My point is, the Tierney 2010 report is a study of the change in Lake Tanganyika surface temperature over time, which contains no measurements of the change in LST over time, and which has exactly three actual surface temperature measurements, which are poorly cited, are from different parts of the lake, and are all from 2003 …
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More information on this paper may be obtained at:
http://www.geo.brown.edu/People/Grads/Tierney/Lake_Tanganyika_Warming.html
Is that proxy TEX86 the same used by Mann for his Hockey Stick? Because the resemblance of the graphs above with Mann´s is surprising.
BillD says:
May 20, 2010 at 6:55 am
I also think that its silly to suggest a conspiracy among scientists from diverse fields and throughout the world, perhaps going back over more than one hundred years.
And yet, here you are suggesting just that. Interesting.
This is the origin of that Proxy :
Project: TEX86 paleothermometry: proxy validation and application in marine sediments
Titel Een nieuwe zeeoppervlaktetemperatuur proxy gebaseerd op membraanlipiden van plankton van Archaea: de TEX86
Abstract Determination of past sea surface temperatures (SST) is of primary importance for the reconstruction of natural climatic changes. The understanding of these changes is essential if we want to decipher human impact on current global change. Several geochemical proxies for SST reconstructions are used but all have problems and assumptions associated with them. Hence, there is a strong need for more and better SST proxies. We recently developed a new SST proxy (the TEX86) based on the relative distribution of tetraether membrane lipids derived from marine Crenarchaeota, a ubiquitous and omnipresent component of marine picoplankton. A preliminary core-top calibration shows a linear relationship of this proxy with SST in the range 0-30°C. Here we propose to further calibrate and validate this new proxy. Small-scale mesocosm experiments, where field populations of marine Crenarcheaota are adapted to different temperatures, will be used to further calibrate the TEX86-SST relationship. In addition, determination of the TEX86 in water filtrates and sedimenting particles from different depth and taken at different times of the annual cycle from several selected sites in the ocean will establish which depth interval and part of the annual cycle the temperature reconstructed from the TEX86 reflects. These data will be compared with an extended core-top calibration of the TEX86-SST relationship. The TEX86 will be further analysed in well-dated cores from the Holocene and Pleistocene and compared with other, previously determined, SST proxies such as the UK37′ and the d18O of planktonic foraminifera. This will yield information on SST during different parts of the annual cycle and depth intervals of the water column. These integrated data will likely result in a new, extensively calibrated SST proxy, which is widely applicable in marine sediments.
http://www.onderzoekinformatie.nl/en/oi/nod/onderzoek/OND1297859/
BillD is claiming that warmth makes these types of lakes clearer. These researchers from UC Davis are saying that warmth will make Lake Tahoe less clear.
“Equally worrying, he said, is the likelihood that when the oxygen is gone, phosphorus that is currently locked up in the lake-floor sediments will get released. This phosphorus will eventually reach the lake’s surface, where it will fuel algal growth. Algae blooms can cause many problems, including reduced lake clarity, unpleasant odors and bad-tasting drinking water.”
http://www.sciencedaily.com/releases/2008/03/080325141202.htm
Interestingly these UC Davis ‘researchers’ unwisely gave 10 years from 2008 as Lake Tahoes’ demise deadline. I’m looking forward to 10 years hence when these guys are revealed as alarmist cranks.
The author of Tex86 proxy:Dr. Stefan Schouten
http://www.nioz.nl/nioz_nl/0e6cb09c5ee7ab62389853828ffa58ba.php
Anthony,
I just hit your tip jar for the cost of that paper – and for 5-6 more papers in the future – just in case, y’know! 🙂 . Its the least I could do…
Keep up the outstanding work!
REPLY: Thanks much!
Mac says:
May 20, 2010 at 3:44 am
“….So why is Lake Tanganyika showing sudden warming of +3F while the surrounding region in this part of Africa has not?”
________________________________________________________________________
In the original article
Tim Clark says:
May 19, 2010 at 8:24 am
“There are numerous studies, including below, that differ with this paper…..
Temperature wise, it is not only the large water mass, but another factor that makes Lake Tanganyika so stable – even more stable and homogenous than the ocean in most places. This factor is volcanic activity near the bottom of the lake…..”
____
BillD: May 20, 2010 at 6:55 am
re Rich Matarese: May 20, 2010 at 4:52 am
and BillD: May 20, 2010 at 4:04 am
I’m sure that Rich can speak for himself if he wishes to bother, but he certainly didn’t mention ‘millions of papers’ – that was your offering – but I have, myself, read thousands of supposedly well-reviewed papers in the ‘climate’ area that I wouldn’t use to wrap garbage. Umbrage, by the way, doesn’t have much of a market value, but it is often a very good ‘proxy’ for ‘degree to which criticism is on target’. Rich also didn’t use the words ‘conspiracy’ nor ‘one hundred years’ – those were your offerings as well – and we all know, as been demonstrated endlessly, that there is no need for an active conspiracy when mutual self-interests converge under the aegis of a prevailing paradigm. It would seem that Rich’s targeting skill is much to be complimented.
/dr.bill
More excellent peer review… the way it is supposed to be done.
In the meantime, someone got a Brown PhD for this, didn’t they?
Gail Combs says:
May 20, 2010 at 9:03 am
It seems to be the case:
Temperature wise, it is not only the large water mass, but another factor that makes Lake Tanganyika so stable – even more stable and homogenous than the ocean in most places. This factor is volcanic activity near the bottom of the lake. The temperature at the bottom of Lake Tanganyika has been measured and turned out to differ no more than 5 degrees F from the surface temperature. The stable temperature has however created sharp changes in oxygen content as you proceed down into the lake. Since there are virtually no temperature changes in Lake Tanganyika, there are no driving forces for vertical currents. Without any vertical currents and water exchange with the surface, the deep soon becomes oxygen depleted. Animals that need oxygen to survive, including of course all the Tanganyika cichlids, can therefore only be found at the top 300 meters of the lake
http://www.aquaticcommunity.com/cichlid/tang2.php
—
BillD laments my mention of Verburg & Heckey (“The physics of the warming of Lake Tanganyika by climate change” Limnol. Oceanogr. 2009, pp. 2418-2430; online at http://tinyurl.com/26xbz5u ), which I’d composed while his slightly earlier recommendation of this publication was apparently awaiting moderation. I’d noted that in this article “there are all the hallmarks of yet another warmist propaganda piece.”
BillD states that “…from being on both giving and receiving end of [Limnology and Oceanography] reviews that they are quite critical, thoughtful and rigorous, and this I do not discredit.
In both my personal experience of peer review and in discussions with medical colleagues on this subject, I know – and, boy, BillD really ought to know – how the peer review process can get screwed up by the sorts of concerted and deliberately deceptive measures practiced by the anthropogenic global warming cabal that was cataclysmically de-pantsed by the Climategate revelations, particularly with regard to the insights provided by the e-mails of the C.R.U. correspondents.
In clinical medicine, we have been subjected for decades to the influences of the pharmaceuticals and medical device manufacturers, who not only fund a great deal of innovative research – which they have to undertake as the result of FDA and other regulatory bodies’ requirements to gain permission to market their products – but who must target the greatest part of their advertising to physicians and other health care practitioners.
What this means is that almost all research-minded doctors must deal with the PhRMA and MDMA member companies when seeking funding, and pecuniary relationships have developed with clinical investigators and “key opinion leaders” in the medical profession which have been recognized for a helluva long time to be conducive to what we’ll call – for politeness’ sake – a certain lack of objectivity in the academic work conducted by these particular in-the-manufacturers’-pockets medicos.
A whole lot of my professional colleagues, Bill, make a bunch more money for being on pharma companies’ “speakers’ bureaus” and serving as lead investigators in proprietary Phase III and Phase IV clinical trials than they do by playing musical exam rooms and actually treating patients.
So with the understanding that I sure as hell know what pervasive influence peddling can do to the process of peer review – because the pharma companies do actively recruit their “key opinion leaders” on the basis of things like editorial clout and that prominence within their specialty which gives them to hold responsibilities in peer review for “high impact” medical journals – you might appreciate why, when I got to read those e-mails in the FOI2009.zip archive last November, my immediate desire was for something brutally Sicilian to happen immediately and with spatter marks on the surrounding walls to the C.R.U. correspondents who had been concerting to infest and pervert the peer review process throughout the physical sciences wherever anything critical of the AGW hypothesis might be brought into publication.
As you, Bill, should realize, it is difficult for an honest peer review officer – even one who does not have a personal pecuniary or professional interest in the support of a particular point of view – to contest an assertion in a manuscript which is clearly supported by a previously peer-reviewed article, a copy of which has come to said review officer along with the manuscript in question, all highlighted and redlined “with circles and arrows and a paragraph on the back of each one explaining what each one was to be used as evidence against us.”
So what does this mean? Simple. In the physical sciences as in clinical medicine, the effects of perverting the peer review process reverberate.
Bad science – once allowed into the literature – is pretty much in the literature forever. It takes exceptional steps on the part of journal editors and the officers of the professional societies to extirpate a bogus clinical study report, and I’ve seen it take years to correct such concerted frauds. Get a look at the 1998 VIGOR trial for an insight into just one of these stinking episodes.
Okay, I’m not in your field. But you’ll have to concede that as a medical man, I’m hyperalert to what “undue influence” in the peer review process can and does mean to the quality of subsequent work in any area. It makes and breaks grant applications, it pervades continuing professional education, it channels subsequent research away from work that truly tests (rather than seeks to validate) a worthless hypothesis….
…like anthropogenic global warming…
…it destroys the careers of young graduate students and postdoctoral fellows, it colors policymaking decisions in industry and government, it does a boatload of damage.
Check again that Verburg & Heckey article and much of the rest of the stuff you’re still extolling, Bill. You’re going to find AGW cabal fingerprints all to hellangone over ’em, directly or indirectly.
This is why I described Verburg & Heckey’s paper as “pre-Climategate,” just I would tend to describe any paper on the COX-2 specific NSAIDS in the context of what we suddenly learned about rofecoxib (Vioxx, Merck) in late 2004.
—
I used to consider proxy data as equal to facts. No longer! I view proxy data with a great deal of skepticism now. Thanks for the education!
Why wouldn’t the last “half century” be the last 50 years? Hence 1960-2010? Shouldn’t the trend lines in figure 3 be from 1960-1985?
Peculiar things tend to creep up, but mostly for propaganda or complete fake studies.
Numbers never lie and internet remembers.
Here’s what I find peculiar with the surrounding of Lake T. and its whole basin, it must be one of those mythological static environments, because for 15 years nothing have changed, the numbers are just the same year after year after, even, after more ‘an a decade. Maybe the fish makes the people in the lake T. basin sterile, but what do I know, except that they never have fished more an 200K ton per year of certain fish’. The one million in 95 and the ten million in the basin have become all the ten million. And the surface temperature during tourist season at least is around 25 C, apparently still. And the lake apparently only empty itself during heavy rain periods only since it’s a “closed” basin.
In Nature 14 Aug 2003 there’s a global crap article about Lake T. too. Pretty interesting numbers. Hah, UN also archives everything. :-()
We’re in the midst of a CAGW propaganda counter offensive doubtlessly to aid the passage of Kerry-Lieberman.
Speaking of proxies, does anyone remember this?
Lucy Skywalker (15:05:46) :
hoxy proxy, pinecones foxy,
records bloxy, treerings poxy,
fire burn and cauldron bubble.
tallbloke (16:14:00) :
Britlecones and hockey sticks all in a row
spark the tinder and watch them glow
the ray of light through the lens of Hubble
lightening the load of toil and trouble
Don’cha hate it when you realize the next morning what you wanted to say the night before? See my [UPDATE] at the end of the head post above …
w.
JB says:
May 20, 2010 at 10:50 am (Edit)
Sorry for the confusion, I meant the last half century of their proxy data.
Gail Combs says:
May 20, 2010 at 9:03 am
It seems to be the case:
Temperature wise, it is not only the large water mass, but another factor that makes Lake Tanganyika so stable – even more stable and homogenous than the ocean in most places. This factor is volcanic activity near the bottom of the lake.
Gail;
Your comments about the stable water column, low oxygen and small change in temperature with depth are all correct according to my understanding. However, there is no evidence at all for geothermal (volcanic warming) of the deeper waters of the lake. The deeper waters are only a few oC cooler than the surface waters because in the tropics, the weather does not get cool enought for long enough to cool such a deep lake.
The change in water density per degree temperature is greater at high temperatures than at lower temperatures. This contributes to the greater resistance to mixing by wind in the tropics and the stability of stratification in Lake T and other tropical lakes. If volcanoes or some other form of geothermal heat affected lake temperature, this would be seen in the depth-temperature thermal profiles. This is how and why geothermal heating was explicitly ruled out in the Vergburg and Hecky (2009) paper.
Willis Eschenbach: May 20, 2010 at 11:41 am
See my [UPDATE] at the end of the head post above …
And that got published. Oh my….
/dr.bill
I swam in the lake late last year. I noticed that the top few feet were warmish and below that it was *extremely* cold. I understand that the lake is about 1/2 mile deep. So wouldn’t you expect that this be taken into account in such a “study” as this? What exactly is the “surface temperature” and why is that more important than the total heat content of the lake?
Rich Matarese says:
May 20, 2010 at 10:10 am
Rich;
I fully agree with you about the conflict of interests in many medical and pharmacuetical studies. One of my brothers was involved in that field and found much evidence of bias and fraud. In such cases, only very rigorous double blind studies have any credibility. Probably the best that can be done is to fully disclose sources of funding and potential conflicts.
Fortunately, researchers involved in environmental studies don’t usually have a direct monetary interest in the outcome, although they are benefited by publishable results. I’ve had a number of NSF grants and can say, in retrospect, that some of my best results have been those that have gone against my expectations and those of most of my colleagues. The most exciting point in research is when I have results that give me confidence that my next experiments will strongly challenge the scientific status quo.
Thus, my experience leads me to a different conclusion than most posters here. Researchers who submit grants with strong tests of and challenges to the prevailing theory are most likely to get funded and published. If most peer reviewed publications support a particular hypothesis or theory, this is because the theory is very solid.
I have often called for rejection of scientific papers where the expermental design and/or data were weak, even though the broader conclusions agreed with my expectations. I have also recommended publication for manuscripts that contradicted my own work and seemed unlikely, when I could not find fault with the design, data and analysis. Peer review is far from perfect, but most scientific research is judged on its scientific merits and not on whether it supports a popular or unpopular hypothesis.
BillD says:
BillD, thanks for the information. The lake is huge, about 350 miles long. In the Vergburg and Hecky (2009) paper, they list a total of only six vertical temperature profiles done over a century … hardly an exhaustive survey. Two of these show warmer water near the bottom, a temperature inversion indicating the possibility of geothermal warming. So I don’t see how that “explicitly rules out” geothermal warming as you (and Vergburg and Hecky) state.
You seem to think that geothermal warming is only a theoretical possibility. See here and here, one of which says:
So when boiling water is known to be entering the lake from hydrothermal vents, and when we only have very inadequate surveying, I’d say it was a bit early to be “explicitly ruling out” anything …
Justa Joe says:
May 20, 2010 at 8:53 am
BillD is claiming that warmth makes these types of lakes clearer. These researchers from UC Davis are saying that warmth will make Lake Tahoe less clear.
In the tropics there is very little seasonal change in temperature and thus, very little mixing. Lake Tahoe does not get cool enough to mix to the bottom, but it does mix as deep as 500 m during winter. The effects of mixing depth and temperature are complex and sometimes subtle. It’s not surprising if the effects of warming differ between tropical and temperate systems. My understanding is that Lake Tahoe is becoming more eutrophic (less clear) and my expectation is that it will remain one of the clearest lakes in North America. It’s a matter of perspective if now or in the future you say ‘great, Lake Tahoe is a very clear lake,” or “too bad, water quality is much degraded from earlier times.” Now and over the next century, both of these perspectives will have some validity. Environmentalists often prefer to look at degredation over time, rather than being satisfied that a particular place (or lake) is better than most others.