Last year, one of the first things that puzzled me about the NAS panel report was the basis for their conclusion that there was no MWP in Antarctica. At the press conference, at about minute 60, North said:
there is evidence of warmth in the record in the MWP. But as Bradley and Diaz a few years ago in Science indicates,. there are many different MWPs and in some places there is not, such as Antarctica. Murky is the right word. There may or may not have been such a MWP over the full globe.
Last year, I observed that the NAS panel didn’t provide any evidence for this claim and tried to figure out what they might have had in mind. Despite two specialists (Tas van Ommen and Eric Steig), no one could figure out what they meant and Steig went so far as to say that their statements were wrong (although he added that no fault should be attached to them for making incorrect statements of this nature.) Here’s an update on this in which I identify the data that supposedly underpins this conclusion – borehole data collected in 1994-96, which the author, Gary Clow, a USGS scientist refuses to release on the grounds that the “results and data are not yet available.”
In my post last year, I excerpted the relevant quotes from the NAS panel and contrasted this with the Law Dome dO18 series which actually showed elevated values at AD1000:
Figure from Jones and Mann 2004 showing elevated dO18 at Law Dome in the MWP
Van Ommen said that dO18 was not necessarily a thermometer and other things affected it as well. That’s fine; I hold no particular conviction that dO18 is a “thermometer” and did not cite this as proof of an Antarctic MWP, but as evidence that this particular ice core was not evidence against an Antarctic MWP. My position on d18O, as I’ve observed elsewhere, is merely that paleoclimatologists shouldn’t suck and blow – if Law Dome reflects regional circulation, fine, but don’t say that d18O that goes up reflects global warming, while dO18 that goes down reflects regional circulation.
Eric Steig, after observing that none of us knew what we were talking and that we should be blamed for our stupidity,
First, it is worth pointing out that your various commenters made a remarkable mess of discussing delta 18O. There is an amazing amount of confusion out there on what is actually a very simple concept. It would help your discussions if your commenters refrained from talking about thing that they have evidently not taken more than 15 seconds to think about, let alone read about. It is such a mess that I feel compelled to explain it on a RealClimate post at some point, so there is no excuse for this sort of confusion in the future.
then said that NAS panel had erred in all the statements that I had highlighted, but should not be blamed because they were not Antarctic specialists.
Regarding the NAS panel statements: I don’t think any of the statements you quote about Antarctica are valid. In fairness the panel was not charged with rigorously evaluating the Antarctic data, …..
His comments seemed a little unfair – excusing a blue-ribbon panel of professors convened by NAS for making incorrect statements, while condemning posters here, even while admitting that my criticsms were correct. Steig went on to say that dating in Antarctic cores was too imprecise to make definitive assertions about the MWP; he himself leaned to the idea that there were contrasting trends in east and west Antarctica. The specialists then swanned off without shedding any light on what the NAS panel might have had in mind when they made their claims. The post and comments are worth re-reading if you’re interested; I won’t re-cap them here. Suffice it to say, I remained puzzled as to the evidence that North and the NAS panel had relied on in asserting that there was no MWP in Antarctica, especially in the face of elevated dO18 values at Law Dome.
At the AGU conference in December, Kurt Cuffey made a presentation which I reported here and I clarified some issues at that time. He presented two borehole diagrams – the Dahl-Jensen borehole from Greenland showing a pronounced MWP discussed here and an Antarctica borehole which didn’t show a MWP. It turned out (and I confirmed this with Cuffey) that the NAS panel argument was based on the different timings of these two borehole diagrams.
What caught my eye at the time was that the “topology” of the two graphics was very similar. The Dahl-Jensen graphic is shown below; the Antarctic borehole looked a lot the same, except that the horizontal scale was dilated differently.
Presented with two curves that are similar up to dilation, my first instinct was to wonder how much certainty could be placed on this dating and whether there was a plausible alternative dating for the Antarctic borehole that might align the two curves. I asked Hugo Beltrami, a noted borehole specialist about ice boreholes, reporting at the time as follows:
I asked Hugo Beltrami about ice boreholes; he said that because glaciers moved, this created additional problems for ice boreholes. I wonder whether a mis-estimate of glacier flow rates could compress the scaling.
Given North had placed considerable weight on the Antarctic situation in the press conference and in arriving at his own view on whether or not their was an MWP, I thought that it would be worthwhile analyzing these two boreholes in detail to see exactly how much weight could be placed on the data. I contacted Cuffey last year and asked him for data on the two boreholes, starting from the pre-inversion information. Cuffey said that I would have to get the Antarctic data from Gary Clow of the USGS. I asked Cuffey for the Greenland data, but haven’t got anything from him. (I’ve only tried 2 or 3 times, not 10.)
Recently I took another pass at trying to get the Antarctic borehole data from Gary Clow of the USGS, an organization which, in general, has a fine record of publishing and archiving information. On April 18, 2007, I wrote to Clow as follows:
Dear Dr Clow,
Kurt Cuffey said that the NAS panel applied your Antarctic borehole results. I presume that these are the Taylor Dome results referred to in http://www.nsf.gov/od/opp/antarct/ajus/nsf9828/9828html/b12.htm . I haven’t been able to locate any archived digital information on these results. Could I get a copy of the reconstruction and the underlying temperature measurements? Thanks, Steve McIntyre
The link cited in my letter is a presentation entitled: Acquisition of borehole temperature measurements from Taylor Dome and the dry valleys for paleoclimate reconstruction, in the Antarctic Journal of the United States Review 1996, stating:
During the 1994-1995 and 1995-1996 field seasons, we acquired high-precision temperature measurements in the 554-meter (m) deep borehole (TD-D) recently drilled through the ice at Taylor Dome (77°50′S 159°00′E).
Clow replied promptly on the same day:
Unfortunately these results and data are not available yet.
USGS – Earth Surface Dynamics
Lakewood, Colorado, USA
also at INSTAAR
Univ. of Colorado
On April 23, 2007, I pursued the matter further as follows:
Wasn’t this work done a long time ago? Kurt Cuffey said that the NAS Panel relied on these results for one of their claims. So I presume that the data was sent to him. I want to respond on this aspect of the NAS panel and would accordingly like to have access to the same data that was provided to Cuffey. Thanks, Steve McIntyre
Gary, I notice that the following website http://www.nsf.gov/od/opp/antarct/ajus/nsf9828/9828html/b12.htm says:
“During the 1994-1995 and 1995-1996 field seasons, we acquired high-precision temperature measurements in the 554-meter (m) deep borehole (TD-D) recently drilled through the ice at Taylor Dome (77°50′S 159°00′E).”
That seems like an adequate length of time to make results available. Regards, Steve McIntyre
He did not reply. So what we have here: we have a National Research Council panel chairman making statements at a national press conference which rely on an unpublished borehole analysis from data collected in 1994-1996, which the author refuses to provide on the basis that the “results and data are not available yet”.
If Clow hasn’t published in the 11 years since the data was published, then I think that he’s waived any rights that he might have to exclusivity on the data. But the situation is much worse than that. He’s selectively disseminated the data. He gave the data to Cuffey, who applied the results in the NAS panel report. Aside from the 11 years, once the NAS panel applied these results based on Clow’s selective dissemination, then Clow and the USGS have no honorable alternative other than to release the data.
Update May 25, 2007
Gary Clow emailed me the following cordial response:
Sorry for the delay in getting back to you regarding the Taylor Dome borehole data; I’ve been bombarded by a series of high-priority requests from within the U.S. Department of the Interior of late that needed my immediate undivided attention.
Just to clarify the situation with the Taylor Dome data, it is position of the USGS to ensure the quality of all data before it’s released. This can take considerable time given our extremely limited staff and a shift in priorities after the acquisition of the Taylor Dome log. Prior to the release of the data, a quality assurance analysis needs to be completed and the documentation approved by the USGS.
Analysis of the ITS-90 temperature measurement uncertainties was completed some time ago. This analysis showed that the total standard uncertainty of the temperature measurement process at Taylor Dome ranged 3.4 – 3.7 mK once the necessary bias corrections are applied. For the borehole paleothermometry climate-reconstruction technique, perhaps a more relevant metric is the standard uncertainty of the relative temperature measurements which ranged 1.8 – 2.0 mK at Taylor Dome.
A comparable analysis of the depth measurements and the associated uncertainties has proved difficult and admittedly has caused some delay. The depth uncertainty analysis, which is finally nearing closure, includes the following effects: thermally-induced radial strains in the measuring wheel and logging cable, thermally-induced longitudinal strain in the logging cable, tension-related strains in the logging cable, the buoyancy of the logging cable and logging tool in the borehole fluid, and tension-induced distortions within the logging winch and level-wind system. The combined standard uncertainty of the Taylor Dome depth measurements, once the necessary bias corrections have applied, will probably be on the order of 300-500 ppm.
The depth and temperature measurement uncertainties for the USGS Polar Temperature Logging System is the subject of manuscript that’s nearing completion. Once this manuscript has received official USGS approval, I’ll be happy to provide you with a copy.
After the manuscript has been approved for release, the next step will be to submit the bias-corrected borehole temperature data to the USGS for official approval. Once approval has been granted, the data can and will be released to the public (it cannot be released until then). Since these data do not yet have official USGS approval, they have not to my knowledge been released beyond the Co-PIs and graduate students directly associated with the Taylor Dome project (Kurt was a graduate student of my Co-PI during the Taylor Dome field days).
The partially-corrected data and preliminary climate reconstructions based on them have been presented at a few workshops. However, until the data and any interpretations based on them are actually published, I don’t believe they should have been cited (it is important that all data and interpretations be subjected to the full review process before they are cited). I hope this helps clarify the situation. I’ll be happy to supply you with the data once they have official USGS approval.
We are making progress on this although it’s admittedly been a fairly low priority compared to our other activities. Thanks for your interest in the MWP. It was an interesting time.
U.S. Geological Survey
While Clow’s response was cordial, it doesn’t really help much in terms of the NAS Report. It also raises some interesting access questions. Under USGS policy, as Clow observes, Cuffey shouldn’t have used this result in his capacity as a NAS panelist. But once he’s done that, you can’t unbreak the egg. It seems to me that the data – in whatever form Cuffey had it – is what’s relevant and this data should be available somehow. Whether or not USGS change their interpretation down the road is irrelevant.