Following (below left) is the Hockey Stick diagram endorsed by Geoffrey Boulton, General Secretary of the Royal Society of Edinburgh, in their December 2009 (post-Climategate) Policy Advice statement Climate Change and the U.N Copenhagen Summit here. On the right is a confirmation plot from data archived in late 2009 and February 2010 by Boulton’s associate and 2007 hire at the University of Edinburgh, Gabrielle Hegerl (showing that I’ve located the precise data version for the Boulton hockey stick.)
Boulton Figure 3 Caption: Estimates of mean decadal temperatures over the land areas between 300 and 900 in the northern hemisphere during the last 1500 years. Prior to the instrumental record of the last 150 years (shown in red), temperatures are deduced from tree-rings, lake sediments and ice cores. The dashed lines show the range of higher frequency variability in the data. The record shows an early mediaeval cool period from prior to about 950AD, a mediaeval warm period until about 1200AD, the so-called Little Ice Age from about 1450 to 1850AD and the very strong late 20th Century warming. Temperatures in sub-surface rocks can be used to deduce long-termchanges in surface temperature that naturally smooth out inter-annual variations to show long-term trends. Temperature records from 631 boreholes have been used in this way to show how distinctive the 20th Century warming has been compared with the preceding 400 years. (From: Hegerl, G.C. and others. 2007. Detection of human influences on a new, validated 1500-year temperature reconstruction; Journal of Climate, 20 (4): 650-666.)
Boulton’s Policy Advice assured his readers that this reconstruction was “independent of the University of East Anglia reconstruction, about which there has recently been much controversy”:
Several independent estimations have now been made of the global or hemispheric average temperatures for the last two millennia. Figure 3 is one of these, and shows that the late 20th Century warming has been rapid and large compared with earlier periods (note that this is independent of the University of East Anglia reconstruction, about which there has recently been much controversy). If we look in more detail at the 20th Century warming however (Figure 3),we see that the pattern of climate change has been much more complex than the smoothly accelerating pattern of greenhouse gas concentration
Hegerl et al (J Clim 2007) describes a couple of different versions of her reconstruction: one step starts in 1505 (12 records) ; one in 1251; one in 946 (7 records) and one in 558 (5 records). Hegerl did not provide accurate digital or even paper citations for the records; the archive is smoothed data. The task of identifying the provenance of each of the series is further complicated by the fact that the only information about the smoothing is that it is “decadally smoothed” – the exact filter is not reported.
The version shown in the Boulton Policy Paper is the 5-record version starting in 558. I’m now in a position to identify the provenance of each of these 5 records – something that takes a lot of patience.
The first record in this group is described by Hegerl as follows:
Western United States: This time series uses an RCS processed tree-ring composite used in Mann et al. (1999), and kindly provided by M. Hughes, and two sites generated by Lloyd and Graumlich (1997), analyzed by Esper et al. (Boreal and Upper Wright), and provided by E. Cook. The Esper analyses were first averaged. Although there are a number of broad similarities between the Esper and Hughes reconstructions, the correlation is only 0.66. The two composites were averaged.
CA readers, but apparently not rigorous Journal of Climate peer reviewers, know that MBH99 goes back only to 1000 and that there is no candidate “RCS processed tree ring composite” in MBH99. Needless to say, this is Mann’s infamous PC1 (from Mann and Jones 2003, not MBH99)- accepted without demur by rigorous Journal of Climate peer reviewers even though Mann’s PC1 and the use of strip bark had been sharply criticized in the NAS panel report. In the CH5 reconstruction, only the PC1 is used (the strip bark foxtails are not averaged in.)
Next is a series described as follows:
Northern Sweden: This is from Grudd et al. (2002) by way of Esper.
This is Tornetrask – a site used in every multiproxy reconstruction that I know of – including, for example, MBH99, Jones et al 1998 and Briffa 2000. Esper’s RCS chronology is only slightly different than the RCS chronology from Briffa (2000). The measurement data used in Briffa 2000 wasn’t archived, but based on the measurement data in Briffa 2008, it looks like the Briffa 2000 and Esper measurement datasets matched. RCS methods are pretty trivial mathematically and thus there isn’t a lot of difference between the two chronologies. This is a ring width chronology (not an MXD density chronology) and, in this case, wasn’t bodged.
The third record is also familiar to CA readers:
Taimyr Peninsula: This is from Naurzbaev et al. (2002) by way of Esper.
Taymir, like Tornetrask, is a Briffa 2000 site and used in most recent multiproxy reconstructions. The Esper version of measurement data is smaller than the Briffa 2008 version, which pulls in some Schweingruber sites (the Briffa 2000 version has never been archived, but is presumably fairly similar to the Esper version.)
The fourth record is a West Greenland isotope series from Fisher et al 1996. This is also used in virtually every multiproxy study: MBH99, Jones et al 1998, Mann and Jones 2003, Moberg 2005, etc.
The 5th record is a Chinese composite from Yang et al 2002, used in many studies. This is used in many recent multiproxy studies as well.
East Asia: This is the high-resolution record (10-yr average) from Yang et al. (2002).
Although this supposedly has 10-year interval, it used the Thompson Dunde ice core previously smoothed to 50-year intervals.
The serial re-use of these proxies is very familiar to CA readers – a point confirmed by Wegman et al (2006).
Far from the Boulton hockey stick – a composite of the Mann PC1, Tornetrask, Taymir, West Greenland isotopes and the Yang composite – being “independent” of the controversial East Anglia reconstructions (regardless of whatever Boulton had in mind here precisely), the Boulton hockey stick is not “independent”.
Boulton and the Team that can’t shoot straight.
See CA category here for prior posts on Hegerl.