NAS Ice Core – Dasuopu

If you look at Chapter 6 of NAS, you’ll see heavy reliance on Thompson’s tropical ice cores. There’s much to consider here and this is a very first look. Here’s an interesting statement:

"A quantitative assessment of temperature change from north Tibetan cores [Dunde and Guliya], using typical [whatver that is in tropical ice cores] isotopic sensitivity, is preliminary, but both suggest warming over the last 150 years of at least 1 deg C."

Since Dunde was only drilled in 1987, it is no wonder that the quantitative assessment is only "preliminary". We at climateaudit have also done a "preliminary assessment" using temperature data rather than "typical isotopic sensitivty" and got different results.

Look at Figure 6-1 showing the plots of 6 Thompson cores (Kilimanjaro is not illustrated – anyone want to bet that it doesn’t have an elevated modern dO18 graph? Didn’t think so. I’ve plotted Kilimanjaro last fall,) In the Andes, 2 of the 3 series have higher MWp than modern, but one series, Huascaran, has very elevated values with the rise occurring in the 18th century and continuing to the present. In the Tibetan cores, the only series with a marked modern increase is Dasuopu, but again, the increase seems to occur throughout the millennium. In the original publication, Dasuopu was said to be a precipitation proxy, but is nonetheless averaged with the other series (dare one say because it has HS), yielding an HS Himalyan composite in Figure 6-2 and tropical composite in Figure 6-3. (Also, by the way, the digital versions of the series in Figure 6-1 are archived as a result of my efforts at Climatic Change. Prior to that, nothing had been archived from Dunde in over 17 years and the file is still limited to decadal dO18).

But that’s not the topic here. The NAS panel says that they used the "four available ice cores from Tibet". OK, but there’s an ice core from Mt Everest; yeah, it’s in Nepal but maybe it would be interesting to compare it to Dasuopu, the most southerly Tibetan site. I think that the following plot is interesting on a number of levels. The bottom panel reproduces the archived data from 1000-1997, which is archived only in 10-year steps, showing that the series has HS.

The top panel zooms in on the 1800-2000 period (with a bigger vertical range) and shows the Dasuopu series in black (with a more compressed look due to the change in scale.) The red series is the archived Everest series from Mayewski, only going back to the mid-19th century, but bringing much information for that period.

First, one notices just how much dO18 information is removed by only reporting decadal information. Mayewski has archived annual (and even sub-annual data). Why should Thompson be permitted to archive only 10-year averages. Second, the scale of variation in Thompson’s decadal series is obviously much smaller than the annual ranges, which are very noisy. Third, the series have different appearances on any scale. I haven’t done a correlation, but I’ll bet that the two series, apples and apples, have negligible correlation. The Everest data seems to have maxed in the 1930s (at about the same time as Greenland temperatures, or for that matter, an earlier U.S. temperature peak – to this day, the record USHCN annual temperature is 1934, not 1998).

What does it mean? It sure doesn’t seem very consistent.


  1. Brooks Hurd
    Posted Jun 23, 2006 at 9:40 PM | Permalink


    I had an opportunity to speak with Thompson last Friday. We both attended a reception after a screening of the Gore film at a theater near the Ohio State University campus. Thompson was being pulled around the reception, thus I could only ask a few questions.

    I asked him about my concern that gases might be lost from ice cores (particularly deep cores) when they are brought to the surface. He told me that they try to keep the cores iso-thermal. I explained that I was not concerned as much about temperature effects as I was about gas losses from microfractures. Thompson explained that he has seen no bubbles in deep ice cores. He said that CO2 is in the form of clathrates. He said that after a day or so, bubbles form in these deep cores.

    I also asked Thompson what percentage of GW he felt was anthropogenic. He said that he thought it was 80%.

  2. Posted Jun 23, 2006 at 10:25 PM | Permalink

    Second, the scale of variation in Thompson’s decadal series is obviously much smaller than the annual ranges, which are very noisy.

    Are the annual ranges really noisy, or is there an real high frequency component that dwarfs the low frequency response in this time frame? I’m assuming that these guys know what kind of repeatability to expect if they collect multiple cores from the same site.

  3. TCO
    Posted Jun 24, 2006 at 6:25 AM | Permalink

    Steve, ever considered doing your own feild study? One of the potential problems with all the compiled research is cherry picking. It would seem that doing your own field study, would show that results can be very variable. It’s not about forensically proving a particular individual (e.g. Jacoby) to have cherry-picked, but just to show that variation is larger then believed. It throws the whole enterprise into larger question. If they come back and say, you have to be a left-handed club-ward to know how to do the field work, you can say fine, publish the exact procedure. And until they do, you can keep going out and gathering more field work, to embarres them. Even if your field work justifies them, so WHAT!! That’s science baby.

  4. Steve McIntyre
    Posted Jun 24, 2006 at 6:42 AM | Permalink

    #3. I’ve been involved in financing and organizing mineral exploratin projects and I know that end of the business (though there are people much better than me). Logging drill core and doing geology is a different job.

    But I was really intrigued by one comment of Alley’s at the NAS panel – that the updating of proxies didn’t really fit with academic projects. I’m sure that I could put together a competitive bid to an update of tree rings in northern Canada (or anywhere else in the world) using geologists to organize logistics – they know how to do everything like that – hire a dendro guy to supervise the field work – get the geologist to do proper mapping and logging, which these guys have poor traditions of – then archive the results as soon as you get them even BEFORE you publish. Now I don’t want to do something like that, I’d never finish what I’m working on, but I could do it. So when I hear all these whining excuses about needing 6 years or 16 years to archive data, or even 2 years, it’s total crap. People got paid to collect the data. Until they got paid, they have a lien on the results, but once they’ve been paid, NSF shouldn’t allow them to hoard the data. While I partly blame the protagonists, most of the blame surely rests with NSF for weak-kneed administration.

  5. TCO
    Posted Jun 24, 2006 at 7:08 AM | Permalink

    They are a government bueracracy. They fund the trendy stuff. They are unlikely to come to the table to sign up for doing rigorous feild studies unless it is directly funded by congress. Still there is other money out there. There are things that can be done with one-offs (if you frigging PUBLISH them, sheesh.)

  6. TCO
    Posted Jun 24, 2006 at 7:20 AM | Permalink

    shoot write a paper on what type of study should be done. And publish that! Along with the other 20 papers that you are delinquent on. I’m still trying to figure out how much is not liking to write and how much is fear of criticism. I’ll shrink that head, though.

  7. Steve McIntyre
    Posted Jun 24, 2006 at 9:38 AM | Permalink

    TCO, John A and others, right now. we’re getting lots of new hits resulting from the NAS Panel and are running at 15-16,000 per day, about 80-100% above normal. I’m going to delete a bunch of posts, including some backbiting. Let’s stay on main topics. There are a lot of people who visit here who don’t post – let’s try to give a little bit of a good impression – OK?

    Let’s also not talk about computer screens. Either wait until another day or send emails to me or John A.

  8. Dave Dardinger
    Posted Jun 24, 2006 at 10:30 AM | Permalink

    Speaking of making a good impression. It’d be nice if at least the regulars would re-read and correct their spelling, grammar, etc. before posting. These messages are forever, essentially. Messages with lots of error indicate lack of forethought and reflection and therefore are easily dismissed.

    I don’t know about the rest of you but I often spend a lot of time on what appear to be hasty posts just deciding what tone to take in a given messsage and I hate it when the occasional typo creeps in.

  9. John G. Bell
    Posted Jun 24, 2006 at 11:58 AM | Permalink

    Re #8, Dave,
    Yep, I cringe when I reread some of my old posts. Steve could add a paypal box for those of us who spent too much time looking out the window during english classes or suffer from bouts of low blood sugar.

    It really annoys me that my spell checker can’t even catch “messsages” in your post ;-).

    John A. $.05 a word? How about $1.00 per logical fallacy? I’d like to think I’d only be nickel and dimed to death. Some here would lose the house.

    Who needs AdSense with ideas like this?

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  1. […] ice core information for Dasupo, Dunde, and Gulaya, is detailed (inter alia) here, here, here, here, here, here, and […]

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