What happened to the Yamal trees - assuming the record was accurate? The Siberian larches are sensitive not only to temperature but also to moisture, nutrients, CO2 and probably other factors, and microclimate issues, perhaps shading from frost, wind, sunlight, neighbouring trees dying, riverbanks shifting.

<<<Click on picture to see animation of Yamal trees in their environment, and note highly local variations.  ^^^Click and zoom on map above to see the prevalence of small ponds and changing river meanders in a flat landscape in Yamal.

It looks like the trees are sensitive to something (see below). But the correlation is not to local thermometer temperature records. The sample of 12 trees used for calibration with thermometers is ridiculously small; this outrage of size of sample is compounded by the refusal to declare the actual sample size and other relevant metadata for 9 years.

I've used the graphs from Jeff Id's work, with treering widths from each tree (black: original data) and red: adjusted in the attempt to eliminate bias due to age of tree). Steve McIntyre said "I think that some information can be gleaned from the nomenclature of the ID numbers... There are 12 IDs consisting of a 3-letter prefix, a 2-digit tree # and 1-digit core#. All 12 end in 1988 or later and presumably come from the living tree samples. The nomenclature of these core IDs url (POR01…POR11; YAD04…YAD12; JAH14…JAH16 - excluding the last digit of the ID here as it is a core #) suggests to me that there were at least 11 POR cores, 12 YAD cores and 16 JAH cores... YAD presumably stands for Yadayakhodyyakha River; POR for Porzayakha River; JAH for one of the unlabelled tributaries" (see CRU archive Figure 3).

Straight away we see a bunch of extremely individual records, plus a complete outlier YAD06. It is warming furiously as the last century draws to a close. It seems to be going nova. But its red-hot condition is not mirrored by YAD04 or YAD12, which both show recent cooling . In fact, none of the others show a steady overall twentieth-century temperature rise, though they all show some increase over the nineteenth century.

By far the strongest correlations among these trees are for individual year spikes, somewhere around 1921, 1939, and 1965. Interesting, because Salehard does record temperature spikes for the years 1924, 1943 and 1967; 1943 and 1967 are mirrored at Turuhansk - maybe temperatures are being picked up. And this is further confirmed by the five POR trees which all show the same warm spikes somewhere around 1921, 1939 and 1965.

But these correlations still fail to support a longterm temperature rise. Sure, the trees in POR all show a warmer twentieth century. But if they correlate with thermometer records, how to explain that the local thermometer record does not correspond over a decadal time-scale, or give an overall rise of 7ºC as Briffa's calibration shows? At the very least, the treerings have been over-sensitively calibrated, as well as given undue weighting for such a tiny sample.

The POR trees all show the early- to mid-nineteenth century as cooler than the twentieth, but also cooler than the end of the eighteenth. Only two of the five, POR03 and POR08, show a warming trend right through the twentieth century that looks like the global temperature pattern, and POR03 shows an altogether warmer eighteenth century. POR01 levels off quite soon in the twentieth century; POR05 and POR11 actually decline towards the end.

POR all go right up from the 1921-1924 spike on; but this is NOT reflected in the thermometer records of either Turuhansk or Salehard, which reflect each other strongly both annually and decadally.

The implication is that while treerings may well show temperature fluctuations from year to year, these local spikes cannot be safely calibrated to show longer, slower climate changes. There are too many individual factors.