Tom Curtis Writes

While CA readers may disagree with Tom Curtis, we’ve also noticed that he is straightforward. Recently, in comments responding to my recent post on misrepresentations by Lewandowsky and Cook, Curtis agreed that “Lewandowsky’s new addition to his paper is silly beyond belief”, but argued that “the FOI data does not show Cook to have lied about what he found. He was incorrect in his claims about where the survey was posted; but that is likely to be the result of faulty memory.”

Showing both integrity and personal courage, Curtis has sent me the email published below (also giving me permission to publish the excerpt shown.) While Curtis agreed that Cook’s statement to Chambers could not possibly be true, Curtis re-iterates his belief that Cook is honest, though he is obviously troubled by the incident. Curtis also reports that, as early as last September, he emailed both Lewandowsky (cc Oberauer) and Cook informing them that no link to the Lewandowsky survey had been posted at the SKS blog, only a tweet – a warning inexplicably ignored by Lewandowsky and Oberauer in their revisions to Lewandowsky et al (Psych Science). Continue reading

April Fools’ Day for Marcott et al

Q. Why did realclimate publish the Marcott FAQ on Easter Sunday?
A. Because if they’d waited until Monday, everyone would have thought it was an April Fools’ joke. Continue reading

The Marcott Filibuster

Marcott et al have posted their long-promised FAQ at realclimate here. Without providing any links to or citation of Climate Audit, they now concede:

20th century portion of our paleotemperature stack is not statistically robust, cannot be considered representative of global temperature changes, and therefore is not the basis of any of our conclusions.

Otherwise, their response is pretty much a filibuster, running the clock on questions that have not actually been asked and certainly not at issue by critics. For questions and issues that I’ve actually raised, for the most part, they merely re-iterate what they already said. Nothing worth waiting for. Continue reading

Aging as a State of Mind

Bobbie Hasselbring, editor of Real Food Traveller, has an article on “Aging as a State of Mind”. Her article concludes as follows:

Katherine McIntyre is 89 years old. She’s the oldest person ever to have zip lined at High Life Adventures. She’s a working travel journalist. And she kept me from even wondering whether I’m afraid of heights. And, you know what? I’m not afraid. Because Katherine isn’t afraid and she’s one of my heroes.

Mine as well.

Lewandowsky Doubles Down

Last fall, Geoff Chambers and Barry Woods established beyond a shadow of a doubt that no blog post linking to the Lewandowsky survey had ever been published at the Skeptical Science (SKS) blog. Chambers reasonably suggested at the time that the authors correct the claim in the article to reflect the lack of any link at the SKS blog. I reviewed the then available information on this incident in September 2012 here.

Since then, information obtained through FOI by Simon Turnill has shown that responses by both Lewandowsky and Cook to questions from Chambers and Woods were untrue. Actually, “untrue” does not really do justice to the measure of untruthfulness, as the FOI correspondence shows that the untruthful answers were given deliberately and intentionally. Chambers, in a post entitled Lewandowsky the Liar, minced no words in calling Lewandowsky “a liar, a fool, a charlatan and a fraud.”

Even though the untruthfulness of Lewandowsky and Cook’s stories had been clearly demonstrated by Geoff Chambers in a series of blog articles (e.g. here), in the published version of the Hoax paper, instead of correcting prior untrue claims about SKS, Lewandowsky doubled down, repeating and substantially amplifying the untrue claim. Continue reading

Bent Their Core Tops In

In today’s post, I’m going to show Marcott-Shakun redating in several relevant cases. The problem, as I’ve said on numerous occasions, has nothing to do with the very slight recalibration of radiocarbon dates from CALIB 6.0.1 (essentially negligible in the modern period in discussion here), but with Marcott-Shakun core top redating. Continue reading

Hiding the Decline: MD01-2421

As noted in my previous post, Marcott, Shakun, Clark and Mix disappeared two alkenone cores from the 1940 population, both of which were highly negative. In addition, they made some surprising additions to the 1940 population, including three cores whose coretops were dated by competent specialists 500-1000 years earlier.

While the article says that ages were recalibrated with CALIB6.0.1, the differences between CALIB6.0.1 and previous radiocarbon calibrations is not material to the coretop dating issues being discussed here. Further, Marcott’s thesis used CALIB6.0.1, but had very different coretop dates. Marcott et al stated in their SI that “Core tops are assumed to be 1950 AD unless otherwise indicated in original publication”. This is not the procedure that I’ve observed in the data. Precisely what they’ve done is still unclear, but it’s something different.

In today’s post, I’ll examine their proxy #23, an alkenone series of Isono et al 2009. This series is a composite of a piston core (MD01-2421), a gravity core (KR02-06 St. A GC) and a box/multiple core (KR02-06 St A MC1), all taken at the same location. Piston cores are used for deep time, but lose the top portion of the core. Coretops of piston cores can be hundreds or even a few thousand years old. Box cores are shallow cores and the presently preferred technique for recovering up-to-date results.

There are vanishingly few alkenone series where there is a high-resolution box core accompanying Holocene data. Indeed, within the entire Marcott corpus of ocean cores, the MD01-241/KNR02-06 splice is unique in being dated nearly to the present. Its published end date was -41BP (1991AD). Convincing support for modern dating of the top part of the box core is the presence of a bomb spike:

A sample from 3 cm depth in the MC core showed a bomb spike. The high sedimentation rate (average 31 cm/ka) over the last 7000 years permits analysis at multidecade resolution with an average sample spacing of ~32 years.

Despite this evidence for modern sediments, Marcott et al blanked out the top three measurements as shown below:

md01-2421 excerpt
Table 1. Excerpt from Marcott et al spreadsheet

By blanking out the three most recent values of their proxy #23, the earliest dated value was 10.93 BP (1939.07 AD). As a result, the MD01-2421+KNR02-06 alkenone series was excluded from the 1940 population. I am unable to locate any documented methodology that would lead to the blanking out of the last three values of this dataset. Nor am I presently aware of any rational basis for excluding the three most recent values.

Since this series was strongly negative in the 20th century, its removal (together with the related removal of OCE326-GGC30 and the importation of medieval data) led to the closing uptick.

BTW in the original publication, Isono et al 2009 reported a decrease in SST from Holocene to modern times that is much larger than the Marcott NHX estimate of less than 1 deg C, reporting as follows:

the SST decreased by ~5 °C to the present (16.7 °C), with high-frequency variations of ~1 °C amplitude (Fig. 2).

A plot of this series is shown below, with the “present” value reported by Isono et al shown as a red dot.

MD03-2421 splice

The Marcott-Shakun Dating Service

Marcott, Shakun, Clark and Mix did not use the published dates for ocean cores, instead substituting their own dates. The validity of Marcott-Shakun re-dating will be discussed below, but first, to show that the re-dating “matters” (TM-climate science), here is a graph showing reconstructions using alkenones (31 of 73 proxies) in Marcott style, comparing the results with published dates (red) to results with Marcott-Shakun dates (black). As you see, there is a persistent decline in the alkenone reconstruction in the 20th century using published dates, but a 20th century increase using Marcott-Shakun dates. (It is taking all my will power not to make an obvious comment at this point.)
Figure 1. Reconstructions from alkenone proxies in Marcott style. Red- using published dates; black- using Marcott-Shakun dates.

Marcott et al archived an alkenone reconstruction. There are discrepancies between the above emulation and the archived reconstruction, a topic that I’ll return to on another occasion. (I’ve tried diligently to reconcile, but am thus far unable. Perhaps due to some misunderstanding on my part of Marcott methodology, some inconsistency between data as used and data as archived or something else.) However, I do not believe that this matters for the purposes of using my emulation methodology to illustrate the effect of Marcott-Shakun re-dating.

ALkenone Core Re-dating

The table below summarizes Marcott-Shakun redating for all alkenone cores with either published end-date or Marcott end-date being less than 50 BP (AD1900). I’ve also shown the closing temperature of each series (“close”) after the two Marcot re-centering steps (as I understand them).
alkenone core redating table

The final date of the Marcott reconstruction is AD1940 (BP10). Only three cores contributed to the final value of the reconstruction with published dates ( “pubend” less than 10): the MD01-2421 splice, OCE326-GGC30 and M35004-4. Two of these cores have very negative values. Marcot et al re-dated both of these cores so that neither contributed to the closing period: the MD01-2421 splice to a fraction of a year prior to 1940, barely missing eligibility; OCE326-GGC30 is re-dated 191 years earlier – into the 18th century.

Re-populating the closing date are 5 cores with published coretops earlier than AD10, in some cases much earlier. The coretop of MD95-2043, for example, was published as 10th century, but was re-dated by Marcott over 1000 years later to “0 BP”. MD95-2011 and MD-2015 were redated by 510 and 690 years respectively. All five re-dated cores contributing to the AD1940 reconstruction had positive values.

In a follow-up post, I’ll examine the validity of Marcott-Shakun redating. If the relevant specialists had been aware of or consulted on the Marcott-Shakun redating, I’m sure that they would have contested it.

Jean S had observed that the Marcott thesis had already described a re-dating of the cores using CALIB 6.0.1 as follows:

All radiocarbon based ages were recalibrated with CALIB 6.0.1 using INTCAL09 and its protocol (Reimer, 2009) for the site-specific locations and materials. Marine reservoir ages were taken from the originally published manuscripts.

The SI to Marcott et al made an essentially identical statement (pdf, 8):

The majority of our age-control points are based on radiocarbon dates. In order to compare the records appropriately, we recalibrated all radiocarbon dates with Calib 6.0.1 using INTCAL09 and its protocol (1) for the site-specific locations and materials. Any reservoir ages used in the ocean datasets followed the original authors’ suggested values, and were held constant unless otherwise stated in the original publication.

However, the re-dating described above is SUBSEQUENT to the Marcott thesis. (I’ve confirmed this by examining plots of individual proxies on pages 200-201 of the thesis. End dates illustrated in the thesis correspond more or less to published end dates and do not reflect the wholesale redating of the Science article.

I was unable to locate any reference to the wholesale re-dating in the text of Marcott et al 2013. The closest thing to a mention is the following statement in the SI:

Core tops are assumed to be 1950 AD unless otherwise indicated in original publication.

However, something more than this is going on. In some cases, Marcott et al have re-dated core tops indicated as 0 BP in the original publication. (Perhaps with justification, but this is not reported.) In other cases, core tops have been assigned to 0 BP even though different dates have been reported in the original publication. In another important case (of YAD061 significance as I will later discuss), Marcott et al ignored a major dating caveat of the original publication.

Examination of the re-dating of individual cores will give an interesting perspective on the cores themselves – an issue that, in my opinion, ought to have been addressed in technical terms by the authors. More on this in a forthcoming post.

The moral of today’s post for ocean cores. Are you an ocean core that is tired of your current date? Does your current date make you feel too old? Or does it make you feel too young? Try the Marcott-Shakun dating service. Ashley Madison for ocean cores. Confidentiality is guaranteed.

How Marcottian Upticks Arise

I’m working towards a post on the effect of Marcott re-dating, but first I want to document some points on the methodology of Marcott et al 2013 and to remove some speculation on the Marcott upticks, which do not arise from any of the main speculations.

In the graphic below, I’ve plotted Marcott’s NHX reconstruction against an emulation (weighting by latitude and gridcell as described in script) using proxies with published dates rather than Marcott dates. (I am using this version because it illustrates the uptick using Marcott methodology. Marcott re-dating is an important issue that I will return to.) The uptick in the emulation occurs in 2000 rather than 1940; the slight offset makes it discernible for sharp eyes below.

emulation -NH
Figure 1. Marcott NHX reconstruction (red) versus emulation with non-redated proxies (yellow). The dotted lines at the left show the Younger Dryas. Marcott began their reported results shortly after the rapid emergence from the Younger Dryas, which is not shown in the graphics.

I have consistently discouraged speculation that the Marcott uptick arose from splicing Mannian data or temperature data. I trust that the above demonstration showing a Marcottian uptick merely using proxy data will put an end to such speculation.

The other “explanation” is that the uptick results from high-frequency swings in individual proxies. Marcott’s email to me encouraged such speculation. However, this is NOT what causes the uptick. Below I show the series that contribute to the NHX weighted average before and after the uptick. The proxy values shown below have been re-centered to reflect Marcott recentering: (1) by -0.66 deg C to reflect the re-centering from mid-Holocene to 500-1450AD; (2) by -0.08 deg C to match the observed mean of Marcottian reconstructions in 500-1450 AD.

Readers will observe that there are 6 contributing series in the second-last step, of which 5 are negative, some strongly. Their weighted average is negative (not quite as negative as the penultimate Marcott value in 1920, but you see the effect.) Only one series is present in the final step, one that, after the two rescaling steps, is slightly positive. Thus, the uptick. None of the contributing series have sharp high-frequency: their changes are negligible. Ironically, the one continuing series (Lake 850) actually goes down a little in the period of the uptick.

excerpt nh unredated

Marcottian uptricks upticks arise because of proxy inconsistency: one (or two) proxies have different signs or quantities than the larger population, but continue one step longer. This is also the reason why the effect is mitigated in the infilled variation. In principle, downticks can also occur – a matter that will be covered in my next post which will probably be on the relationship between Marcottian re-dating and upticks.

I have been unable to replicate some of the recent features of the Marcott zonal reconstructions. I think that there may be some differences in some series between the data as archived and as used in their reported calculations, though it may be a difference in methodology. More on this later.

CG3: The Gold Medalist

bolt_mann Last summer during the London Olympics, Josh had some fun with the “Climate Olympics”, with Mann at left in the iconic gold medal pose of Usain Bolt, the famous runner.

Little did we know that during an earlier Olympics, Jones was disappointed at being silver medalist in statistical abuse – to gold medalist Mann. CG3 1093965453:

date: Tue Aug 31 11:17:33 2004
from: Phil Jones

subject: Fwd: On the Role of Statistics in Climate Research, Tim Lambert, Phil Jones et al?
to: Rasmus Benestad

Rasmus and Mike,

In the email below, Mike seems to have won the gold medal for statistical abuse and I have the silver. I seemed to have tried too hard to explain my techniques. I tried really hard to get the gold medal – Mike has a degree in maths/stats ! I’ll have to redeem myself in AR4 and switch the places for the 2008 Olympiad – the AR4 coming out in 2007 should put me well in the lead.

I clearly didn’t allow for the knowledge of the judges – I think I’ll appeal!


The category remains hotly contested, with many new contestants. Jones, whatever his other sins, has tended to use fairly simple methods and I find it hard to picture him maintaining a spot on the podium. Mann, of course, has a repertoire of upside-down techniques that are highly regarded by climate referees and which make it very difficult for new contestants to seize the gold medal.