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 …
Willis Eschenbach says:
May 20, 2010 at 1:00 pm
Willis:
You make a good point and I was not aware of these thermal vents. On the other hand, one needs to compare the volume of the vents to the volume of the lake (>18,000 cubic km). I am a limnologist, but physical limnology is not my specialty. I assume that Verburg and Hecky (2009) are correct in their estimate of 0.04 watts/m2 per year of geothermal heating for Lake T. This means that vents or other extreme temperature imputs have a negligible effect. My understanding is that Lake T is strongly meromictic and that the deeper anaerobic waters neven mix with the surface. This is tested by salinity gradients, carbon isotopes and other means as well as the limited thermal profiles. Since the deeper waters are very isolated from the surface and several degrees cooler than the surface waters, this means that the 3 oC heating of the surface cannot be caused by the (cooler) bottom waters.
You are correct of course, that it would be nice to have more data.
Here’s a link that provides some overview: International Lake Environment Committee (although I can’t vouch for the accuracy of anything they list).
A bit down the page there are some graphs of vertical temperature profiles, and a comment saying that the temperature below about 80 meters is stable at about 23.4°C. Given the depth of the water, the relatively small vertical turnover, and the limited outflow (one river), it is surprising (to me) that the temperature at depth isn’t stable at about 4.0°C, as it is in most other lakes of reasonable depth.
There obviously has to be some ‘heat in this pipeline’ that isn’t being accounted for.
/dr.bill
To save someone the trouble of correcting me, after succumbing to the mouth first, brain later syndrome in my previous post, I realized that I was being ‘parochial’ and thinking of temperate-climate lakes. Perhaps I should get out (of Canada) more often. 🙂
/dr.bill
Justa Joe says: Lake Tahoe
While I do not agree with the alarmist Tahoe scenarios– the conditions are very much different between Tahoe and Tanganyika. Tahoe has a strong temperature gradient at low temperatures. The melting ice as an example sinks in the Spring (water has a max density at 4C) allowing the relatively warm bottom water to move to the surface. Tanganyika is warm with very little temperature gradient from top to bottom. It takes a tremendous amount of energy – in the form of winds- to cause vertical mixing.
The important point in this discussion is it is the wind that is important in Tanganyika (if upwelling is found to be the primary control on productivity). Unless it can be shown that rising temperatures are associated with stronger winds-temperature in the range discussed may not have much of an impact. The Lake Tanganyika Regional Fishery Programme found in its modeling that temperature is of secondary importance in the upwelling that brings the nutrients to the surface.
The sad fact is the Lake’s dynamics are extremely complex and we have sacrificed our chance to understand for a simple correlation with temeperature.
BillD says:
May 20, 2010 at 1:17 pm
Willis Eschenbach says:
May 20, 2010 at 1:00 pm
Thanks, Bill. I can’t find the paper that was used by Verburg and Hecky to get the 0.04°/m2 heat flux. But my point is slightly different. V&H are giving general geothermal heat flux. But hydrothermal vents don’t provide heat across the whole floor like geothermal heat flux, they are point sources. In a stable lake such as Tanganyika, the hot plume would flow straight up. As such, you would never see evidence of those vents by vertical temperature sampling unless you sampled right on top of one … and with a total of six samples over a century in an area of 231,000 square km …
In any case, a couple of those six samples showed deep temperature inversion, which is suggestive if nothing else. I find it astounding that the authors of the study come to their broad and sweeping conclusions with such a tiny amount of actual data, especially with the indications that other confounding factors are present. Given the hot springs, some at temperatures above boiling, it is obvious that this is a thermally active area. I don’t see how that can simply be neglected. I tried to mention that in my piece that was published in Nature Magazine, but the reviewers axed it. They said if I couldn’t prove it was significant, I couldn’t mention it … which seemed backwards to me, the onus is on the authors to exclude it rather than on me to prove it makes a difference.
Willis-
I came across a paper by Coulter http://www.aslo.org/lo/toc/vol_13/issue_2/0385.pdf who offered the possibility of heat flow at the bottom of the lake to explain the apparent lack of an expected salinity gradient. (Well before the discovery of the Banza vents) He also offered that relatively small heat inputs (given the lake age and depth and using Lake Malawi as an example) could create convection currents. This would make the nutrient cycling dynamics far more complex than simple temperature and wind.
“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.” – BillD
Sorry Bud, I’m not buying. There is an objective way of measuring clarity of the lake. How accurate these methods are may be an issue. Anyway You seem to want to cover for these UC Davis ‘researchers’. I fully expect there to negligible measurable difference to the ‘quality’ of Lake Tahoe within 8 years from now. That is in stark contrast to the wild eyed claims of these researchers.
Number #2; I find it interesting that a seeming natural lessening in clarity of Lake Tahoe in the mind of the self styled environmentalist correlates to degradation. (I’m not saying that the lake IS losing clarity.) Lake Tahoe gains it’s clarity by natural reasons by contrast Lake Michigan is murky natually. That doesn’t make Lake Michigan a lesser lake. If we have to judge things based on the perceptions of environmentalists we’re really in trouble. (sorry to digress)
I haven’t read the article on Lake Tanganyika because actually it holds little interest for me, but if the lake is gaining clarity shouldn’t you guys be heralding it as an improvement?
“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). ”
—…—
Sounds like they just verified that the MWP and LIA occurred in mid-Africa as well as the rest of the world. Looking in more detail in the 20th century: They show “real measured temperatures” decliing from a peak in the 1930-1940 timeframe towards a low point in early 1970 -> then a steady rise from 1970 on.
And their apropimate proxy reading fails – going well past the measured temperatures, and appears to be “calibrated” towards the peak of 0.8 degrees. Though they claim a 2 degree rise from their approximate proxies – but why?
What did it rise from – and rise to – if the max temp change in the graph (even though it ends incorrectly high at 0.8 degrees instead of about 0.40 average local change) isn’t 2.0 C?
Pat Moffitt
May 20, 2010 at 2:33 pm
“The sad fact is the Lake’s dynamics are extremely complex and we have sacrificed our chance to understand for a simple correlation with temeperature.”
Boy you sure got right. Lake Tanganyika is one of the most complicated lakes in the world. In some ways it is really two lakes. Its chemistry, temperature, and geology are not consistent from end to end. The effects of weather on the lake is not consistent either. On top of this, the geology is active and has a major impact on the lake.
Lake Tanganyika is evolving. The natural changes that have occurred, even within the time of recent memory, make any study like this sound ludicrous.
Willis Eschenbach> I’m kind of confused here. You say that Tierney et al. do not calibrate the TEX86 proxy. But according to the supplementary material that you link to, they do pay a lot of attention to this calibration (see table S3 in the supplementary material).
“While I do not agree with the alarmist Tahoe scenarios– the conditions are very much different between Tahoe and Tanganyika.” – P. Moffit
I concur, but I don’t think that someone can say that in the case of Tanganyika necessarily that warmer = clearer.
Some back of the envelope calculations … the paper says that a small amount of diving discovered 72 “groups of chimneys”, with each chimney venting from “one to several” litres per second.
If we figure say 10 chimneys in each group, and an average of 2 litres per second per chimney, and that the tiny amount of diving has only found 1% of the vents, and the water temperature coming out of the vents is 80°C, then they would warm the lake by 1° C in about 70 years …
However, in addition to the hot water that is flowing out, the ground around the hot springs must be warm as well. If the geothermal flow is 0.04 w/m2, the numbers look like this:
0.04 w/m2 flow
2.31E+05 square km lake area
2.31E+11 square m lake area
9.24E+09 watts instantaneous heat flow over lake area
8.10E+13 watt-hrs/yr over lake area
2.92E+17 joules/yr over lake area
1.80E+19 grams of h2o in the lake
62 years/1°C raise in temp
As to whether that is significant, I don’t know, because water is flowing into and out of the lake … but that’s assuming about the global average heat flow. Since the lake bed is obviously a thermal area, the flow may be more. If it is double that, the time would be halved.
Finally, I don’t think that if this heating were even, there would necessarily be a temperature inversion in the vertical temperature profile. It seems that it would simply reduce the slope of the decrease of temperature with depth … but then I’m not a limnologist.
Check my numbers, I’ve been wrong before …
mb says:
May 20, 2010 at 3:51 pm
Thanks, MB. While they do talk about the TEX86 proxy, I don’t think they can calibrate it to this particular lake, because they have no temperature series to calibrate it to. They do say they calibrate it against the lake itself, but they give absolutely no indication as to what temperature dataset they are using or how they are doing the “calibration” … which makes me suspicious. I suspect that they are simply adjusting the variables to give some particular modern day temperature …
So basically all they can do is look at how it works in other lakes and then play with the variables, which is a general estimation (a SWAG) rather than a calibration.
Finally, the authors say:
Sounds like “guess at the numbers” to me … particularly when (as I show in Figure 3 above) the results don’t agree with the air temp data.
Justa Joe says:
Lake Tahoe gains it’s clarity by natural reasons by contrast Lake Michigan is murky natually.
Lake Michigan is a very good example of a biological as opposed to physical control on water clarity– the zebra mussel. The zebra mussel’s filtering ability has led to a substantial increase in Lake Michigan’s water clarity over the past few decades. There is often a price for “clearer water” – less productivity evidenced by reduced salmon biomass and interference with some near shore spawning success of bass etc . But this again depends on what biomass you are trying to maximize.
Perhaps the most overlooked environmental catastrophe is the collapse of oyster populations – the result of two diseases Dermo and MSX along the East and Gulf Coasts (as well as overharvest etc). It has been estimated that the historic oyster population in the Chesapeake Bay system filtered the entire water volume every 3 days. Think about what it would take in terms of human construction to accomplish this task. (Without the oysters we get prolific algal blooms and increased temperatures and without knowledge of the oyster’s function we could make some fundamental mistakes interpreting sediment TEX 86 proxies! Bivalves “short circuit” primary production. No- I’m not making a Tanganyika bivalve link.) We can spend all the money we want on point or non-point pollution control measures–but without this keystone species it will never achieve the water quality, habitat or ecosystem goals. (Unfortunately, but not unexpectedly, there are relatively few resources being applied to the diseases or restoration. Oysters just doesn’t fit our environmental crisis model. Now if we could just blame climate change…..)
One last point on clarity- we can also see increasing water clarity when we over-fish a species that consumes the zooplanktion or algal grazers. (like overfishing the clupeids in Tanganyika? As well as changes in the “relatively more” anoxic zooplankton refuge zone which is outside the clupeid zone of comfort)
For many ecosystems if you find the answer to a question simple- you haven’t understood the question.
Pat Moffitt says:
May 20, 2010 at 4:50 pm
Justa Joe says:
Lake Tahoe gains it’s clarity by natural reasons by contrast Lake Michigan is murky natually.
Lake Michigan is a very good example of a biological as opposed to physical control on water clarity– the zebra mussel. ….
________________________________________________________________________
Fasinating.
Perhaps you could write an article for WUWT about the repercussions of oversimplification (blaming AGW) instead of doing real science in the field of biology. The people who truly care about the environment do not understand the havoc that has been done thanks to AGW zealotry.
I pray that God continues to fill Willis Eschenbach with bountiful life force so that he can continue his amazing work. In Climate Science, no other is as good as Willis and no other demonstrates his level of energy. Thank you, Willis Eschenbach.
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BillD, dismissing my observations about the pervasive adverse impacts of the corruption of the peer review process in the physical sciences by the C.R.U. correspondents confirmed in the Climategate archive, writes:
“Fortunately, researchers involved in environmental studies don’t usually have a direct monetary interest in the outcome, although they are benefited by publishable results.”
God damn. Where the hell has this guy been for the last thirty years? Would anybody else reading on this thread care to clue him in about how many people in “climatology” and the allied sciences must be said (to paraphrase Kipling) “to have been shown the way to promotion and pay” through their allegiance to the anthropogenic global warming fraud?
“Researchers who submit grants with strong tests of and challenges to the prevailing theory [if we can dignify the AGW “Cargo Cult Science with the term ‘theory’] are most likely to get” shut to hellangone out of funding, publication, position, tenure, and advancement in their professional disciplines.
Is this not very much the case?
Oh, well. While we’re at it on the subject of bad research, Bill, why don’t you speak with your brother about clinical research funded by the pharmaceuticals and devices manufacturers and ask him about how even “…very rigorous double blind studies [which you describe as having] any credibility” can be jerked around to provide data for studies that are fundamentally deceptive by way of suggestio falsi, suppressio veri.
Look into that New England Journal of Medicine reference I provided earlier. A paper reporting a “rigorous double blind” study – the VIGOR trial – was submitted to NEJM in 1998, got through peer review at one of the most up-tight journals in the world of medicine, and – by way of cherry-picking the data submitted (selecting out some study subjects whose adverse events histories which, if considered, would’ve significantly affected the safety profile for rofecoxib and revealed something that Merck really didn’t want us prescribers to learn about their “blockbuster” product – was published to be touted by Merck’s marketing weevils as solid proofs of Vioxx’s tolerability, efficacy, and safety.
Research can be conducted with pretty good rigor, Bill, and the publications derived from that research can be duplicitous as all hell.
And those publications can and do get through peer review. In the pharmaceuticals and medical devices industries, Bill, there are highly-paid people who work full-time to no purpose other than “strategic communications planning,” taking the raw material of studies like clinical trials and torturing the data until it is made to say – in “high impact” periodicals like The New England Journal of Medicine just exactly what is to the greatest advantage for the manufacturers who had funded the studies.
Now, with far more money riding on the foisting of the AGW fraud, just what the hell gives you to sit before your computer right now, Bill, and try to push the notion that “researchers involved in environmental studies don’t usually have a direct monetary interest in the outcome,” hm?
On average, a pharma company sinks close to a billion bucks into research to bring a new chemical entity (NCE) all the way to success in the submission of a new drug application (NDA), and they’re looking – if they get themselves a “blockbuster” – at making back about a billion bucks a year until the product goes off-patent.
That, Bill, is bloody nothing compared with what the C.R.U. correspondents and their fellows were leveraging in the “carbon trading” racket.
And a company like Merck, pushing their selective COX-2 inhibitor into “blockbuster” profitability, killed and crippled only a few thousand people.
As the AGW fraudsters have been getting their way – until that sudden “Whoa!” imposed by Climategate – they’ve been killing literally millions by way of starvation alone, and future policies predicated upon their hideous, utterly rotten scheming will, if implemented, condemn hundreds of millions more real human beings to poverty, misery, suffering, and death.
And for what? Their ability to crow at the peak of their own particular academic dungheaps? To gain the praise of corrupt professional politicians and similar thieving goniffs? To get invested in “carbon futures trading” and make some cash for themselves?
Look, when the story over the VIGOR trial broke back in 2004, I remember Merck sales representatives – “detail men” – getting pounded pretty viciously by physicians all over the country. They were the unfortunate guys in the front lines who were the “face” of Merck to those of us who diagnose the patients and write the prescriptions. While they were going around asking for the return of the Vioxx samples they’d been piling on us for months preceding, they took a lot of crap.
But the people I really wanted to confront were those clinical investigators who signed their names to that VIGOR trial report, and the peer review officers and editors at NEJM, damn them.
Well, on a far grander scale – and for much better cause – I’d really like to see Prof. Phil Jones and Dr. Michael Mann and Hansen and Briffa and all the rest of those weasels go up against the wall right alongside Algore and those humping sons-of-indeterminate-fathers Kerry and Lieberman.
Wouldn’t you, Bill?
And if not, why not?
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Gail Combs writes “…about the repercussions of oversimplification (blaming AGW) instead of doing real science in the field of biology.”
Speaking personally as someone who does not much “…care about the environment” (I have a largely adversarial relationship with all my descendants, and actuarially speaking, I’m not going to outlive Barry Soetoro unless we all get real lucky and something happens to severely embarrass the Secret Service in the next couple of years, so the environment is going to have to get along without me pretty soon now), I’m obliged by education if not by professional experience to observe that biology imposes a number of confounding factors on the analysis of the admittedly minimal data collected by Tierney et al in this letter, and to wonder (as I had yesterday, in the preceding thread) just how hard it would’ve been for these clowns to take under reasonable consideration the confounding factors of both wholly natural and human biological influences puissant in the basin responsible for the existence of Lake Tanganyika before doing what is equivalent to my three-year-old granddaughter holding up an Easter egg and proclaiming proof that the Easter Bunny not only exists but had penetrated my back yard the night before to leave gaudy hard-boiled henfruit in the grass for her to find.
If, in their Nature Geoscience letter, Tierney and her colleagues had been content to report what they’d found, and to inform readers of their plans to conduct additional research to expand upon these findings and add significantly and with ingenuity to the body of knowledge on Lake Tanganyika, I’d be quite happy, and wish them the best of good fortune.
But these clowns just have to brandish their Easter egg – and it really ain’t that spectacular a bit of decoration when you get right down to it, is it? – and proclaim: “Proof yet again that evil anthropogenic carbon dioxide forcing is destroying our beloved Mother Earth!”
Sheesh. And this got through peer review at Nature?
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What if all the assumptions used by Tierney et al to claim a climate change signature for Lake Tanganyika are either wrong or unsubstantiated? Victor Langenberg’s 2008 thesis (Wageningen University) On the Limnology of Lake Tanganyika seems to take just this position. His position:
• No evidence of increasing lake clarity as a result of secchi measurements since 1946
• The interplay of stratification and plankton productivity are not “straightforward”
• Challenges O’Reilly’s assumption on the correlation of wind and productivity -the highest production is on the end of the lake with the lowest winds
• A strong caution using diatoms as the productivity proxy (it is one of two different lake modes)
• No ability to link climate change to productivity changes
• More productivity from river than allowed for in Nature Geopscience article
• Externally derived nutrients control productivity for a quarter of the year
• Strong indications of overfishing
• No evidence of a climate and fishery production link
• The current productivity of the lake is within the expected range
• Doesn’t challenge recent temp increase but cites temperature records do not show a temperature rise in the last century
• Phytoplankton chlorophylla seems to have not materially changed from the 1970s to 1990s
• Disputes O’Reilly’s and Verbug’s claims of increased warming and decreased productivity
• Rejects Verburgs contention that changes in phytoplankton biomass (biovolume), in dissolved silica and in transparency support the idea of declining productivity. A large part of the lakes production may be picocyanobacteria
It will be interesting to watch the grant support for these two young Ph.D graduates Tierney and Langenberg- one claims clear climate change negative impact- the other sees no evidence for climate.
We do know that Langenberg’s work did not garner international media attention
I recommend reading Langenberg’s thesis- especially his personal 8 year history living along the Lake. It is the first paper I have seen that mentions sampling locations were often correlated with those areas with less bullets in the air.
Pat Moffitt, I can’t thank you enough for that excellent recommendation to the Langenberg thesis. It is available here. It is real science, and it is as unlike the Tierney study as anything you can imagine. It deals with those old-fashioned things like measurements and instruments and data and the like, not with proxies for things that we have no way of calibrating or verifying.
My best to you,
w.
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Pat Moffitt recommends Langenberg’s thesis On the Limnology of Lake Tanganyika (2008) and Willis provides a link to the full PDF download thereof.
Damn. Was this work even considered by Tierney et al in the preparation of their letter? Of their references, I have proximal access only to their listing in the supplementary information, which recounts seven items, and Langenberg’s work is conspicuously absent from that list.
Let’s assume that the peer review officers and editors of Nature Geoscience are reliably familiar with the subject of freshwater limnology. Wouldn’t one of them – at the very least – have bumped the manuscript of this letter back to the authors with an admonition to review Langenberg’s very recent publication – which Willis demonstrates is freely accessible online- and incorporate in their submission some indication that they had at least taken due note of such observations, analyses, and conclusions as had come into the literature by way of Langenberg’s thesis?
Given this failure on the part of the Nature Geoscience editorial staff, isn’t it the duty of outsiders – almost assuredly including Langenberg himself, if he is alerted to this utterance scheduled for dead-tree-format publication in June – to offer the editors of this journal some commentary on the methodologies, results, and conclusions of Tierney et al?
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Theo Goodwin says:
May 20, 2010 at 6:34 pm
Theo, many thanks for your prayers and good wishes. I read what you said to my wife Ellie, and she said to be sure to tell you “For goodness sakes, don’t tell Willis stuff like that, his head is too darn swelled up already.” When I tried to protest that I couldn’t tell you something like that in public, it was far too embarrassing, she told me to shut up and get on with it.
So there you are. I never could say no to that woman …
Willis, Tierney et al were on to something they didn’t even notice and you in your analysis of their methodologies has added confirmation and rigor to the unnoticed discovery.
You analysis demonstrates that Tierney were close but had it backwards about TEX86 in Lake Tanganyika used as a proxy.
They have proved that TEX86 in Lake Tanganyika is teleconnected to global temperature without realizing it and thus this single proxy can be used to reconstruct global paleoclimate, similar to, and perhaps more robust in this teleconnection, to the Graybill Bristlecones.
You have added to the work by demonstrating that the proxy signal is completely independent of local temperature influences.
You guys should team up. This is the holy grail of paleoclimatology.
Rich Matarese says:
May 20, 2010 at 10:10 am
I’m thinking that these researchers belong on the ‘Group W bench’….