Polar Urals: Shiyatov’s Finnish Academy Article

I’ve written on a number of occasions on Briffa’s Polar Urals reconstruction, which is used in nearly every multiproxy reconstruction, no doubt because of its uniquely cold MWP. It’s one of the key series in Crowley and Lowery [2000] and Jones et al [1998]; it’s not as important in MBH98-99 (which is more or less just the bristlecones in the MWP. Here’s some information from a relatively inaccessible source: Shiyatov, S.G. Reconstruction of climate and the upper treeline dynamics, Publications of the Academy of Finland 6/95, 144-147.

The full article is posted up here. It says (and this sure sounds different than Crowley):

From the middle of the 8th to the end of the 13th, there was intense regeneration of larch and the timberline rose up to 340 a.s.l. The 12th and 13th centuries were most favorable for larch growth. At this time the altitudinal position of the timberline was the highest, stand density the biggest, longevity of trees the longest, size of trees the largest, increment in diameter and height the most intensive as compared with other periods under review.

Here’s a diagram (rotated from the original) showing the height of the medieval trees as contrasted with the modern trees.

Figure 1. Height of Polar Urals Trees (Shiyatov, Acad. Finl)

By comparison, here is Briffa’s reconstruction, which hardly seems to represent the same area. Briffa’s reconstruction shows a cold period around AD1200, while this is the time of the highest treeline in the entire record.

Figure 2. Briffa’s Polar Urals Temperature Reconstruction

For someone supposedly concerned with low-frequency changes, you’d think they’d pay some attention to the altitude of the trees. I’ve tried unsuccessfully to get data on the altitude of individual cores to do a more detailed study. I really do have an interest in this stuff; I’m not pounding on unarchived data for the sake of pounding on it. I’ve had a practical interest in it or I wouldn’t have inquired.

5 Comments

  1. Paul Gosling
    Posted Aug 4, 2005 at 9:18 AM | Permalink

    Steve Its a bit difficult to comare the two as Briffas graph does not start until the 10th centruy. But from the start of the 11th C to the mid 13th Briffa does show a fairly consistent rise in temperature. I doubt the tree line would react fast enough to respond to the short term variation.

    Steve: But Briffa’s level ~AD1200 is about the same as his level ~AD1650, while the altitudes of the trees are completely different. If desnity is not a function of altitude per se, as Briffa argues, and it is a function of temperature, then one should presumably apply a lapse rate to adjust.

  2. Paul Gosling
    Posted Aug 4, 2005 at 9:19 AM | Permalink

    PS the link to the article does not seem to work. Steve: fixed

  3. John A
    Posted Aug 4, 2005 at 10:28 AM | Permalink

    Re #2

    It works for me.

  4. Paul Gosling
    Posted Aug 5, 2005 at 2:46 AM | Permalink

    Steve

    I don’t really know how tree ring data is standardized. But for a single sample altitude will not have an effect, the tree does not move. When comparing two trees, say 200m appart (altitude), presumably the comparison is in the year to year variation. Not between the wood density of tree a and b. Presumably there are then some standardised trees which are correlated with measured temperatures? I guess the ideal situation would be sample over an altitudinal gradient, but I doubt they have it?

    As for tree lines. I have been thinking about them. I know for a fact that tree lines are depressed by grazing. Though whether this is a factor in the northern Urals I don’t know. The rate of reaction of tree lines will also depend on longevity of tree species. Larch is relativelty short lived so should be much better than bristlecones. I worry a bit about Shiyatov’s data because the maximum change in altitude is only 60m. That is a very small change in temperature. It looks much stronger in the actual article with tree rings etc.

  5. Posted Aug 5, 2005 at 7:38 AM | Permalink

    What is the sample support for this study?

    Tree-rings? Which trees, what trees?

    All rather unscientific

2 Trackbacks

  1. By Lamarche on Treelines #2 « Climate Audit on Jul 28, 2011 at 2:02 PM

    [...] of treeline elevations that I’ve seen is at the Polar Urals site, which I’ve shown here and here. The really odd coincidence – and I don’t believe in coincidences – is [...]

  2. […] noted Shiyatov’s work on treeline changes at Polar Urals in an early Climate Audit post here, which relied on Shiyatov 1995 and Shiyatov 2003, quoting Shiyatov (1995) which […]

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