Circling Yamal 2 – meet the delinquents
Posted by Jeff Id on October 16, 2009
A guest post from Lucy Skywalker. Lucy has taken the time to locate and collect information on a variety of sites related to the Yamal debacle including a useful interactive Google map.
|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.
Conclusion: These Arctic trees, stressed by being “on the edge”, respond in a highly individual way, and to many factors. The same hypersensitivity that shows up year-to-year temperature differences, that enables dendrochronology to work for dating events, makes the tree rings into markers of local fluctuations but not good markers of even decadal trends, let alone longterm climate trends. However, the evidence of changing treelines might work. And in Yamal, the treeline was further north in the Middle Ages.
Jim Bouldin said at Climate Audit:
The ring width data from all the series, past and present, are lined up by cambial age chronology (cambial age = the relative age of each ring, from the pith or tree center). The average of the ring widths for each ring, over all the trees is then computed. This creates a “standard curve” that reflects primarily the size-dependent part of the growth response of the trees. This mean value series is then subtracted, ring by ring, from the actual ring widths of each tree, thus removing the diameter-related ring width component from each tree, since the goal is to isolate the environmental signal. The residuals from this detrending are then examined to see how “complacent” they are, meaning how much they vary from year to year. Those that vary the most strongly are the most sensitive to the environment, and whether they were responding to the same environmental factor is assessed by looking at the spatial similarity of the variation pattern across trees, across the area of interest.
But this last statement does not seem to be borne out by the above highly individual, very different trees.