I’ve written on several occasions about Juckes’ use of cold water G Bulloides as a supposed temperature proxy (following Moberg’s equally indefensible use of this proxy.) It has come to my attention that a leading specialist, David Black of the University of Akron, had already issued a scathing denunciation of Juckes’ use of G Bulloides as a temperature proxy.
Black, an assistant professor of geology at the University of Akron, said that Juckes’ group did not use data on percentage G Bulloides properly in concluding that the 20th century was warm and the MWP ordinary. Black said that the record of G. Bulloides plankton in ocean sediment collected offshore provides a proxy record of the strength of trade winds. But “winds don’t meet any definition of warm, wet, or dry,” he points out.
See the first comment for the rest of the story.
Climate Audit 
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David Black is a published specialist on G bulloides (Science) and has even archived high-resolution data on G Bulloides levels in sediment here
He did make sharply critical comments about using G Bulloides as a temperature proxy, using virtually the exact words in the above thread. However, his criticism was not of Martin Juckes et al, but of Soon and Baliunas. He did not criticize the use of high G Bulloides levels to prove 20th century warmth relative to the MWP, but the use of high G Bulloides levels to prove MWP warmth relative to modern warmth.
The exact quote from Chronicle of Higher Education:
I’m sure that it’s merely due to the exigencies of other activities that Dr Black criticized the Soon and Baliunas publication in Climate Research, but did not criticize Moberg’s use of G Bulloides as a direct temperature proxy in the obscure journal Nature.
I have a little trouble understanding why it’s wrong for Soon and Baliunas to use percentage G Bulloides as a proxy, but OK for Moberg and Juckes to use G Bulloides not just as a temperature proxy, but as their most important proxy in establishing a modern-medieval difference. Maybe someone from Team-world can clarify this.
See earlier thread here.
The earlier criticism of Soon and Baliunas raised many points such as
and
and
This was Mann et al. On Past Temperatures and Anomalous Late-20th Century Warmth Eos,Vol. 84, No. 27, 8 July 2003 and there should be no presumption that such essential points should also apply to teleconnected work by the Team.
Wind speed and hence upwelling and bulloides abundances in the Arabian Sea can be conjectured to be a monsoon-linked teleconnected response to heat over Eurasia. The circulation patterns around the Cariaco basin are of course different, and it may not be possible to link them to extra-regional warmth. Both these hypotheses are easy to test for the last 100-150 years with the hadcrut gridded temperature dataset.
Just because proxies fail in one location, doesn’t mean they cannot be used in another.
#1 — Maybe a polite email asking Prof. Black for clarification is in order. What’s good for Soon’s and Baliunas’ goose is good for Moberg’s and Juckes’ gander, after all.
I’ve read the paper Black criticised. From the way he wrote his criticism, it appeared that he misunderstood what Soon and Baliunas wrote. S&B wrote this: “For questions 1 and 2, we find the answer to be Yes’ when the proxy record shows a period of 50 years or longer of cooling, dryness or wetness during the Little Ice Age and a period of 50 years or longer of warming, wetness or dryness during the Medieval Warm Period. (bolding added)” Where “anomaly” is defined as a 50+ yr sustained period of warmth, wetness or dryness during the MWP or coolness, wetness or dryness during the LIA. They accept that the LIA and the MWP actually happened and were global, which may be what incensed the AGW advocates.
Soon and Baliunas replied to Black’s criticism in a letter sent to the Chronicle of Higher Education (2003 Oct. 10, Vol. 50(7), B4) that also referred to a longer discussion here (MS Word file). They point out that in E&E 2003 their criteria included, “the context of local or regional sensitivity of the proxies to relevant climatic variables, including air temperature, sea surface temperature, precipitation and any combination of large-scale patterns of pressure, wind and oceanic circulation (bolding added).” Black’s G. bulloides trade winds proxy certainly includes “large scale patterns of wind … circulation.”
In Table 1 of their E&E 2003 paper, they reckon Black’s Cariaco Basin core to answer ‘yes,’ ‘yes,’ and ‘no’ to the questions: 1) “Is there an objectively discernible climatic anomaly occurring during the Little Ice Age, defined as 1300’€”1900 A.D.?” 2) “Is there an objectively discernible climatic anomaly occurring during the Medieval Warm Period, defined as 800’€”1300 A.D.?” and 3) “Is there an objectively discernible climatic anomaly occurring within the 20th century that may validly be considered the most extreme (i.e., the warmest) period in the record?”
In the paper itself S&B attached dry or wet (not hot or cold) to the Cariaco Basin proxy. They correlated those findings to coincidental LIA cold aridity or MWP warm moisture, respectively, as observed elsewhere. S&B clearly didn’t use Black’s G. bulloides themselves as a temperature proxy. Black’s 1999 Science paper discussing G. bulloides in the Cariaco Basin definitely connects trade wind intensity with distant patterns of rain, in a manner consistent with S&B’s use of his proxy. It appears that Prof. Black had no valid grounds for complaint.
Indeed, an email to Dr. Black would be useful, rather than putting words in his mouth. Against, my better judgment, let me weigh in here with my opinion. Yes, I am the David Black in question, and as such, I like to think I know my data as well as anyone else. My criticism of the S&B paper stands for reasons that I will get into shortly.
G. bulloides abundance in Cariaco Basin sediments is a proxy for trade wind variability, not local sea surface temperature (SST). If one looks carefully at Fig. 1 in the Science paper, one can see that the correlation coefficient with local SSTs is near-zero, and definitely not statistically significant. While there is certainly a teleconnection with northern North Atlantic SSTs, G. bulloides abundance in the Cariaco Basin is not a SST proxy. This is not to say that G. bulloides could not potentially be used as a SST proxy elsewhere, but a site-specific calibration would have to be demonstrated.
My criticism of the S&B paper was based on several issues. The fact of the matter is that based on the way they set up the paper, the could not have come to any other conclusion than they did. Most of the warming during the 20th century has occurred within the last 40 years, thus causing problems when looking for 50 year periods of extended warmth. My data is about trade wind variability, which says nothing about local warm/cold or wet/dry. As such, it is not appropriate to use my data set based on the way S&B defined the set-up. Even if one wanted to stretch my data (“stretch” being the operative word) to be interpreted as temperature, then this creates problems too. Based on the higher G. bulloides = colder northern North Atlantic SSTs, than the base of my record indicates a colder MWP, not a warmer one. Additionally, how can one characterize a period that spanned five centuries with a record that barely captures the last fifth of it?
Dr. Black, could you please make a direct comment on the use of G. bulloides as applied by Moberg and Juckes in temperature proxies?
Thank you, Dr. Black, for this contribution, #5. Further commentary eagerly awaited.
Dr Black, thanks for your comments. My question was as follows:
The issue is not whether your criticism of S&B was right or wrong – for the purposes of this thread, let’s stipulate that it’s right. My point was that what’s sauce for the goose is sauce for the gander. If the bulloides proxy is, as you say, inappropriate as a temperature proxy at Cariaco, I am unaware of any basis for distinguishing its use from the Arabian Sea. Indeed, the existing evidence strongly indicates that the reasons for your objection at CAriaco apply equally forcefully to the Arabian Sea. On this issue, you merely said:
HOwever, I am unware of any such site-specific demonstration for the Arabian Sea. Anderson et al 2002 (posted up here) described G bulloides in the Arabian Sea as a wind speed proxy – just as you had described the same proxy at Cariaco. I have carefully examined Moberg et al 2005 and have been unable to located anything that remotely resembles a demonstration of a “site-specific calibration” for bulloides as a SST proxy. The discussion in the SI to Moberg et al simply says that proxies for this area are scarce and used this “proxy” without any “site-specific calibration”.
As a result, I take it that you are in agreement that the criticisms that you levelled against S&B 2003 apply equally to the use of Arabian Sea G Bulloides as a direct temperature proxy by Moberg et al 2005 and Juckes et al 2006.
BTW after Pat Frank suggested that I send you an email, I did make an attempt to locate your email address. I soon noticed that you’d moved on from Akron. I was unable to locate a webpage for you earlier this month. I then went to AGU and didn’t try to locate an email address for you from your past coauthors. When I re-googled, I noticed that you have a new webpage as of December 18, 2006. If this reflects a new appointment, congratulations or, if the new webpage merely reflects an older appointment, I’m glad to see that, in either case, you’re now active at a university that seems to be relevant to your interests.
I have not read either the Moberg et al. (2005) or Juckes et al. (2006) papers yet, and as such, I am holding off on voicing an opinion. As you might imagine, I will be more than happy to add my two cents after taking a look at the relevant data.
As I am sure most people in this discussion are aware, it is theoretically possible to reconstruct SSTs using foraminiferal abundance data alone through the use of transfer functions, modern analogue techniques, etc. (e.g. CLIMAP). Admittedly, those techniques have issues of their own – as does every climate proxy. Never the less, within the limitations of a given proxy (which most authors discuss, but there will always be critics), paleoclimate reconstructions are becoming increasingly robust.
That being said, if an author is going to make the case that % G. bulloides (or % any species) is related to SST, I would hope that an argument is presented that links the two together. Anderson et al. (2002) did link G. bulloides abundance to wind stress, and actually carried it one step further than I did by linking G. bulloides abundance to the square of the wind stress, which is a more accurate interpretation of the Ekman-induced upwelling (and rather clever, too).
However, as I’ve mentioned before, upwelling intensity does not necessarily equal SST. Potentially, part of the problem is that it intuitively makes sense to think that SSTs are controlled by upwelling intensity. That is, more upwelling results in colder SSTs. In the region of the asian monsoon, I suppose one could make the argument that surface temperature changes are causing a differential in the land-sea temperature gradient, and hence a change in wind-induced upwelling variability. But again, I would like to see data that shows a correlation between the regional wind stress and the temperature gradient. Then I might be willing to buy into %G. bulloides as a quasi-surface temperature proxy. In this case there is at least a direct physical mechanism that links the two. In the case of my 1999 data, while there was a strong correlation between G. bulloides abundance and nothern North Atlantic SSTs, the mechanism that linked the two was not as direct as what I described for the Arabian Sea. The relationship is also unfortunately not stable with time (e.g., the MWP issue that I brought up). This may be (probably) a result of changes in local fertilization (African dust), but I will play more with this in a currently in-prep manuscript.
Interestingly, the Mg/Ca geochemistry of G. bulloides tests is an excellent proxy for SST, but that is part of a different recently submitted manuscript, and I will save the punch line for when it is hopefully accepted.
Steve – thanks for the congratulations. The web page you found is a result of a new appointment, one that I am extremely thankful for. You have to love Google – they found and indexed the new page within one day of it being put up on the university web site.
Here’s a url for Moberg. Juckes is at Climate of the Past Discussions, but simply relies on prior use by Moberg rather than any independent validation. The SI for Moberg is here with the following proxy description in the SI here
I’ve seen a preprint of Mg/Ca on one of these cores and was thinking of posting up a comparison to the G Bulloides series. Maybe I’ll do that a later today.
Here’s a graphic from a presentation by Oppo showing the difference between the Mg/Ca SST proxy and the percentage bulloides proxy at Arabian Sea core 723B.