Over at Climate Audit, Steve McIntyre has found yet another unexplainable inclusion of a hockey stick shaped proxy in the PAGES2K paper. What is most interesting about it is that when you look at the proxy plot panel, it reminds you of the panel that Steve plotted for Yamal, where just one proxy sample went off the rails as an apparent outlier and seems to dominate the set. Since even a grade school student could pick this proxy out in one of those “which one of these is not like the others?” type test questions, one wonders if this particular proxy was preselected by Kaufman specifically for its shape, or if they just bungled the most basic of quality control inspections. Of course, when Steve asked those questions, Nick Stokes showed up to defend the indefensible, and hilarity ensued.
Steve McIntyre writes:
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Kaufman and paleo peer reviewers ought to be aware that the recent portion of varve data can be contaminated by modern agriculture, as this was a contentious issue in relation to Mann et al 2008 (Upside Down Mann) and Kaufman et al 2009. Nonetheless, Kaufman et al 2013 (PAGES), despite dozens of coauthors and peer review at the two most prominent science journals, committed precisely the same mistake as his earlier article, though the location of the contaminated data is different.
The contaminated series is readily identified as an outlier through a simple inspection of the data. The evidence of contamination by recent agriculture in the specialist articles is completely unequivocal. This sort of mistake shouldn’t be that hard to spot even for real climate scientists.
Here is a plot of the last nine (of 22) Arctic sediment series. One of these series (top left – Igaliku) has the classic shape of the contaminated Finnish sediment series (often described as upside down Tiljander). Any proper data analyst plots data and inspects outliers, especially ones that overly contribute to the expected answer. The Igaliku series demands further inspection under routine data analysis.
Figure 1. Plot of last nine (of 22) Kaufman et al Arctic sediment series. The Igaliku proxy is total pollen accumulation.
The Igaliku series is plotted separately below. It is also available at a NOAA archive here , which actually contains one additional recent value plotted in red. The NOAA archive contains many other measurements: it is unclear why Kaufman selected pollen accumulation rate out of all the available measurements.
The resolution of the data set is only 56 years (coarser than the stated minimum of 50 years) and only has three values in the 20th century. The value in 1916 was lower than late medieval values, but had dramatically surged in the late part of the 20th century.
Figure 2. PAGES2K Igaliku series.
Igaliku is in Greenland and was the location of the Norse settlement founded by Erik the Red and is of archaeological interest. Sediment series from Lake Igaliku have been described in three specialist publications in 2012:
Massa et al, 2012. Journal of Paleolimnology, A multiproxy evaluation of Holocene environmental change from Lake Igaliku, South Greenland. (Not presently online). (Update: online here h/t Mosher. I’ve added a paragraph from this text referring to pollen accumulation.)
Massa et al 2012. QSR. A 2500 year record of natural and anthropogenic soil erosion in South Greenland. Online here.
Perren et al 2012, 2012. Holocene. A paleoecological perspective on 1450 years of human impacts from a lake in southern Greenland. Online here.
The three articles clearly demonstrate that the sediments are contaminated as climate proxies.
Igaliku has been re-settled in the 20th century and modern agricultural practices have been introduced. The specialist publications make it overwhelmingly clear that modern agriculture has resulted in dramatic changes to the sediments, rendering the recent portion of the Igaliku series unusable as a climate proxy. Here are some quotes from the original article.
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Read Steve’s entire essay here: More Kaufman Contamination
Nick showed up to argue that the Igaliku really isn’t contaminated by agriculture at all, and is currently engaged in an multi-front battle of deny, duck, and cover. The obstinance on display to prevent admitting the obvious is diamond hard. This isn’t unusual, as Nick was associated with CSIRO, where admissions aren’t part of the government funded manual. Gadflies and racehorse comparisons were bandied about and now Steve has taken to calling Nick “racehorse” much in the same vein as Tamino and his self proclaimed “bulldog” status.
To say watching this is entertaining, would be an understatement. Meanwhile there have been many updates and piling on of additional evidence for contamination. Nick is now reduced to rebutting Steve with Bill Clinton style questions (“It depends on what the meaning of the words ‘is’ is.”) such as: “Could you say exactly what you mean by “contaminated core”?”
Here is my contribution that I left as comments:
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Steve writes:
The three articles clearly demonstrate that the sediments are contaminated as climate proxies.
Igaliku has been re-settled in the 20th century and modern agricultural practices have been introduced.
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By way of support for this, photos can tell you a lot.
Google Earth’s aerial view clearly shows the developed agriculture signature:
And from the ground, hay bales in Igaliku from the Wikipedia page on Igaliku:
The slope of the land drains right into the lake, and along the slope is clearly human agricultural development.
O’Rourke and SOlomon 1976 have recently found that total pollen influx was a direct function of sediment influx in varved sediments from seneca Lake, New York.
Given the drainage pattern of the land, it seems like a clear case of sediment contamination to me.
Kaufman has followed his rules, which are to use proxies which:
“(5) exhibit a documented temperature signal, and (6) are
published in peer-reviewed literature as a proxy for temperature”
One wonders though if Igaliku wasn’t preselected due to the shape of the data without any other considerations.
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Note: the Google Earth image is of the town near the fjord, the Wikipedia picture of the lake where sediment was sampled is in the highland just to the NW of the town. You can inspect the map here and see the lake (which is ice-covered in the satellite photo):
http://maps.google.com/maps?q=60.987778,-45.420833&ll=61.009153,-45.439453&spn=0.053414,0.185394&t=h&z=13
Update: here is another view of the lake from the ground, showing agriculture all around the catch basin, thanks to Nick and anonymoose http://www.panoramio.com/photo/12426959
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EdeFPosted Apr 30, 2013 at 12:27 AMIgaliku reminds me of the small farms in the Okanogan River valley of central Washington state. Note that dirt would wash into the lake from the several roads going up to the higher country.
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Anthony WattsPosted Apr 30, 2013 at 12:37 AMExactly, basically what agriculture does is increase the pollen catch-basin area though land use change. Fighting runoff and erosion is always an issue with agriculture.
With a larger area near the lake having undergone land-use change, it will allow more runoff, and therefore more pollen to be funneled into the lake. Kaufman was probably never a farmer and wouldn’t get this, or maybe he simply didn’t want to since that uptick looks so “elegant” when trying to fit the theory to the data.
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Anthony WattsPosted Apr 30, 2013 at 1:14 AM
Figure 2 from PAGES 2K has an interesting pollen bump from about 1150-1400.
I think I’ve found a proxy for that. Modern day Igaliku is on the same site as Garðar, Greenland, which had a period of growth during the MWP.
Garðar was the seat of the bishop in the Norse settlements in Greenland.
Garðar had enough success as a town to warrant the Catholic Church to issue a permanent Bishop for the construction of a cathedral there. The first bishop of Garðar, Arnaldur, was ordained by the Archbishop of Lund in 1124. He arrived in Greenland in 1126. In the same year he started with the construction of the cathedral, devoted to St. Nicholas, patron saint of sailors.
To support something like that, you need a successful agricultural base. People that are starving don’t have time for such luxuries.
Bishop Álfur was ordained in 1368 and served as last bishop of Garðar until 1378. The Greenland diocese disappeared in the 1400s, when the ship departures from Norway stopped.
If you look at this table of Bishops, it seems to correlate with that bump in the pollen data, then dives after 1400.
Bishop Served years
Arnaldur First-Bishop 1124–1126
Bishop Arnaldur 1126–1150
Jón Knútur 1153–1186
Jón Árnason 1189–1209
Þór Helgi 1212–1230
Nikulás 1234–1242
Ólafur 1242–mid-1280
Þór Bokki 1289–1309
Bishop Árni 1315–1347
Álfur Last-Bishop 1368–1378
Source: http://en.wikipedia.org/wiki/Gardar,_Greenland
A timeline is here: http://www.greenland-guide.gl/leif2000/history.htm
Bishops would seem to be a proxy for the success of the town, and the success of the town had to rely on the sea and agriculture. When the climate turned colder, the agriculture failed, as we have heard about other areas of southern Greenland.
Of course the pollen bump due to agriculture would have been smaller then than now, since they had no mechanization to amplify the area they could till and plant.
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Bishop Hill might like the Bishops proxy, but Mosher added the real clincher though:
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“Norse farmers settled southern Greenland *985 AD(Jones1986) including the area around Lake Igaliku,which was used for grazing and hay production.Following the disappearance of the Norse *1450 AD,Igaliku was resettled during the 18th century (Arne-borg2007) and large-scale agriculture, based on sheep farming, was developed in the 1920s (Austrheim et al.2008). Consequently, the response to climate changeover the last millennium was overprinted by land-use effects (Gauthier et al.2010; Massa et al.2012; Perrenet al.2012). However, the consideration of human-induced changes at Lake Igaliku in light of the entire Holocene ecosystem development provides new insights about their magnitude.Relative to the preceding Holocene shifts, the vegetation was slightly impacted by land clearanceand grazing, and exhibits a small decrease in woodytaxa abundance (from 60 to 45 %). Until *1335 AD,the related soil erosion, documented by high TOC/TNand MAR values, clearly compounds the long-termincreasing trend (Fig.6). Contrary to the other studiedvariables, the diatom assemblages indicate that thelake ecology was not significantly impacted, and that the changes are within the range of natural Holocene variability.Both in terms of lake ecology and soil erosion, theperiod since 1988 AD is likewise unprecedented in the context of the Holocene by a magnitude and rate of change greater than the previous 9,500 years. The digging of drainage ditches for hayfields caused adramatic increase in MAR, which reached unprece-dented values. The use of nitrogen fertilizers on thesefields (200–250 kg ha -1 yr -1of N, Miki Egede pers.commun.) have outpaced the natural buffering capac-ity of Lake Igaliku, resulting in a sharp rise in themesotrophic diatom, Fragilaria tene
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Nick, in classic Mannian style, refuses to concede. Go help him out at the Climate Audit thread More Kaufman Contamination which is sure to become a classic.
This Stokes-Kaufman incident seems to be a case of land use effect denial.
“Nick showed up to argue that the Igaliku really isn’t contaminated by agriculture at all, and is currently engaged in an multi-front battle of deny, duck, and cover.”
Never underestimate the power of denial:
Anthony, where did you find that Pop Sci cover? And how did you find it? +10
REPLY: Trade secret, sorry – Anthony
Nick Stokes says:
May 1, 2013 at 8:40 am
‘Excluding data ex post, in CA terms. And presumably, urging Kaufman to overrule the original peer reviewed and published result on the basis of his farming knowledge, or whatever. So your demand is “unequivocally condemned at Climate Audit”.’
Here it is again but in a stronger form. Because the proxy appeared in a peer reviewed journal then the authors of all later articles are not only justified in using it but are wrong to use empirical evidence to challenge it or exclude it. (You can say that it is excluded “ex post” because it appeared in a journal. The idea that something appearing in a journal makes it “prima facie” reliable is risible.)
What I want to see is a radical re-investigation of all temperature proxies by scientists who understand scientific method to the extent that they will conduct experiments to challenge the proxy records. No spin can make this need go away. To this day Mann’s proxies haven’t been challenged by experimentation or other means of empirical research. For that fact alone, all paleoclimatologists have egg on their faces.
“Nick here’s something that will “stick” that you refuse so far to answer – show an uncontaminated proxy with a similar shape, per McIntyre. – Anthony”
Anthony, Steve has been clamoring for “ex ante” rules. Kaufman has been trying to follow such rules. Now you want him to go through ruling anything out that doesn’t “look right”?
I did ask Steve what he meant by “contaminated” – he never responded.
REPLY: Nick, just stop blustering and answer the question, your credibility is being harmed by your denial and misdirection, although you clearly can’t see this. It is OK to admit you were wrong, you might even find it liberating. – Anthony
Nick Stokes: A depressing, but sometimes amusing thing about these arguments is the way people bring in one argument after another. Anything that might stick.
The exclusion criteria were listed, and the authors included a series that ought to have been excluded by their criteria. You’re defending that? It’s an illustration of inattentiveness, also called “slopiness”. Perhaps the criteria could have been reworded to something like “mean sampling interval” no more than 50 years, or whatever. But the series violated the criteria as written.
Nick Said
1.“But my main argument, put several times, is this. Climate Audit stated very firmly, just a few days ago “
“Perhaps the greatest single difference between being a “real climate scientist” and policies recommended here is that “real climate scientists” do not hesitate in excluding data ex post because it goes the “wrong” way, a practice that is unequivocally condemned at Climate Audit and other critical blogs which take the position that criteria have to be established ex ante: if you believe that treeline spruce ring widths or Arctic d18O ice core data is a climate proxy, then you can’t exclude (or downweight) data because it goes the “wrong” way.”
I argued against this point on CA a few days ago, viz., it’s nonsensical to include data that is obviously unreliable. Most of the CA posters disagreed with this contention and asserted that all data from a selected set should be incorporated in the reconstruction regardless of the outcome.
I followed the discussion fairly closely and recall that Steve qualified the quoted comment in a later post by mentioning that he had “long argued for careful examination of proxy sets used in reconstructions”. That is to say, I believe he softened his position on the matter. Nonetheless, any ambiguity in the matter can rightly be viewed as selective “auditing”. Steve had demonstrated he is a man of honor on numerous occasions and I hope he clarifies his position on the topic.
Clearly, contaminated data must be rejected weather it goes the “right” way or the “wrong” way. The “Statistical Purists” need to stand aside, as this is a simple case of common sense trumping textbook statistics.
“A depressing, but sometimes amusing thing about these arguments is the way people bring in one argument after another. Anything that might stick. We have a whole head post that goes on about pollution, contamination etc, and now this alleged shortfall is plucked out. Where does it come from?” -Nick Stokes
Agreed. Whats with all these people *criticizing* data sets?! We’re trying to do science here and it cant be done if people keep trying to pick it apart. Sometimes I feel like Steve et al dont even *want* to make the world a better place!
/sarc
Anthony ” …answer the question…”
There are no other pollen series in the Arctic – it’s a rare commodity there. As for other proxies, they come in all kinds of shapes – I have a plotter here. And no, I can’t see anything that looks exactly the same.
But I think you should answer, what kind of decision process do you actually want? People can, and do, raise endless objections – this soil has been disturbed, the wind might have changed etc. At some stage, someone has to decide, OK or not. Do you really want Kaufman to make decisions on the fly?
Pages2k have criteria which in effect say that the decision should be made by the original authors, their reviewers and journal editors. They do actually think about these issues. Can you think of a better way for deciding?
REPLY: Much like weather stations issues of siting contamination, each proxy used should be individually inspected and sanity tested as well as statistically tested. Paul Dennis analysis of the raw data against the cubic spline for example. Problem is, we seldom see this level of attention to detail in real climate science, but rather there’s this tendency to assume it is OK because somebody else had used it in some peer reviewed paper. Paleoclimatology is rife with such spurious oversights, mainly because of confirmation bias, and such concerns get swept under the rug. This needs to change. The uncertainty level of paleoclimatology is anomalously high compared to other sciences. – Anthony
Anthony,
I’d avoid insinuations of Nick being “on somebody’s payroll”. As you of all people know, those sort of accusations are not conducive to constructive debate.
Also, while you and Nick may disagree at times, it is worth pointing out that he goes out of his way to try and make the data in many of these studies easier to understand and analyze, e.g. http://www.moyhu.blogspot.com/2013/04/emulating-marcott-et-al.html and http://www.moyhu.blogspot.com/2013/04/active-viewer-for-pages2k-proxies.html
REPLY: OK fair enough, I’ll withdraw that and just say he’s “obtusely pigheaded” when it comes to accepting shortcomings in climate science. Sometimes when somebody displays such traits, the lack of cognizance in the face of the obvious suggests they are being put up to it.- Anthony
A relation to Pilt Down?
It seems to me that Nick is winning this argument on points.
I think it plausible that agricultural activity will increase runoff and hence increase varve depth.
I think it plausible that pollen density will increase with warming temperatures in cold climates.
All other things being equal, that would suggest increased pollen density per varve might be an unequivocal signal of temperature increase in the arctic area, as long as the pollen of the plants being cultivated can be excluded.
However, these clarifications were not in effect when Kaufman et al wrote their paper.
So I think Nick is correct that there is an element of ‘post hoc’ adjustment here if the discussion is of pollen density. The increase in runoff from human activity may be different from a change in pollen density.
REPLY: problem is that runoff increases pollen load in the sediment due to pollen being embedded in the upper layer of soil that gets eroded….IMHO it is impossible to distinguish this from a temperature signal. – Anthony
Nick Stokes: You show admirable patience and temperment in your postings, good on you. But search the annals, Nick, and show us where you ever conceded a point. If you find one example, take it and frame it for me, please, and many thanks.
Re: Pop Sci Cover and “Trade Secret”.
Thanks for the laugh and the detour into the archives.
Here’s a blog worth a bookmark that resembles my father’s basement.
http://blog.modernmechanix.com
Heck, even the ads are entertaining. Such as Sci Am Sept 1977: Introducing Apple II.
and this one: The Five Dumbest Products in America (but not for long.)
http://blog.modernmechanix.com/the-five-dumbest-products-in-america/1/#mmGal
There seem to be several issues here:
1 Is the Igaliku series contaminated? Answer, don’t know but possibly.
2 Should the Igaliku series be rejected if it may be contaminated? Answer, well that is a very good question. If it is contaminated then – yes but if it isn’t then – no. But if we aren’t sure and it just doesn’t feel right, should we throw it out then? That doesn’t seem right either.
Perhaps point 3 will help.
3 Should the Igaliku series be further investigated if it looks funny? Answer, YES. Obviously, it should be looked at more closely. There isn’t much pollen at those latitudes so we can’t cross-reference. This series needs to stand on its own merits. If it seems extraordinary then it needs extraordinary proof.
Three data points in the twentieth century forming a line is not extraordinary.
But it may be real. Surely the question is “Why mix the extraordinary proxy with the unsensational proxies before removing doubts about the extraordinary proxy?”
Because ‘he did it first’ is not good enough. The proxy needs to be understood, not the understanding outsourced to another paper.
It’s the methodology behind not understanding the chosen proxies that hits a nerve.
Statistics needs consistently applied rules but the rules must be suitable for the data. No consistency in sample selection will avoid picking a duff proxy if the duff proxy is completely out of the expected range that the rules were originally designed for. You need to understand your proxies.
Lest you run the risk of Garbage In Garbage Out.
I guess i have to add Nick Stokes to list of Climate “Scientists” whose opinions should not be accepted until verified by outsides sources.Welcome to the scientists rogue gallery.
Are his talking points coming from the Al Gore propaganda site?
Lawrence Todd says: May 1, 2013 at 12:01 pm
I disagree and urge you to be more understanding of differing views.
In this case I don’t agree with Nick Stokes.
But he is well reasoned and consistent.
He doesn’t play silly word games.
He doesn’t try to deceive
He just happens to think that discarding proxies without knowing about the proxies is wrong.
I think accepting strange looking (and unique at this latitude) proxies without knowing lots about them is wrong.
But he is not a rogue. He may even be right and I may be wrong, or we both could have missed the point.
But being on the other side doesn’t make Nick Stokes a villain.
‘… defend the indefensible …’
Ain’t that the truth.
Ooh the irony, I love it, here is a hockey stick showing clear evidence of an anthropogenic influence on the lake and they deny it! Who are the real deniers???
Whats even more ironic, is when the proxies go down in the 20th centuary they are quick to point out its modern influences from man such as co2 enrichment etc….(thats when they are not hiding it!)
I trust Steve is preparing a rebuttal with refs and photos. Amazingly, like wildebeests coming to the river to drink – they don’t seem to know there is a croc waiting!
“none so blind as those who will not see “or in Stokes case “do not want to see”
Stokes would argue that black is white if there was a Hockey Stick on it.
As an applied mathematician, and data administrator and doing a similar job to what Nick Stokes and others are doing, I looked carefully are every outlier and only included them if it had additional verification.
Nick Stokes says:
May 1, 2013 at 10:38 am
“But I think you should answer, what kind of decision process do you actually want?”
Go to the site and perform experiments there. Go to other sites in the same region where there has been no agriculture in the last 100 years and do experiments there. Compare the two.
What is difficult about that? It is what any serious scientist would do.
Nick Stokes
‘There are no other pollen series in the Arctic ‘
Just has there is no such thing has ‘good ‘ dog sh*t there is such thing has good use of such poor data. And 1000-1 if it had gone the other way you been calling it out has rubbish . Has a scientist the facts are supposed to speak for themselves not be used has ventriloquist dummy to speak words of political advocacy, a issue most climate ‘scientists’ seem to have .
Nick Stokes says:
May 1, 2013 at 10:38 am
There are no other pollen series in the Arctic –
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Nick, what do you see wrong with this?
Theo Goodwin says: May 1, 2013 at 1:22 pm
Nick Stokes says:
“But I think you should answer, what kind of decision process do you actually want?”
Go to the site and perform experiments there. Go to other sites in the same region where there has been no agriculture in the last 100 years and do experiments there. Compare the two.
If that was necessary, it was for the original journal to demand it. Kaufman has an ensemble of 59 proxies to consider. He can’t do that.
But again, he has assembled 59 proxies, and it’s just one region. That’s a lot; he doesn’t need to spend years in the field personally getting more.
” Latitude says: May 1, 2013 at 2:12 pm
There are no other pollen series in the Arctic –
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Nick, what do you see wrong with this?
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I think Latitude says it all.