As noted yesterday, Jacoby and Cook didn’t get the memo about not using the Dulan juniper chronology of Wang et al 1983 (also used in Crowley and Lowery 2000) and used it in a panel diagram in Gou et al [Ann Glac 2006]. Wang et al 1983 is unusual in a dendroclimatic publication, because they identify the location and altitude of every core that they took. This is made easier by the fact that they only used 3 cores, not even close to minimums required according to dendro standards. Of the cores, one was nearly 200 km away from the other two. As shown below, there has been a great deal of subsequent dendro work done in the area, much of reported in the Western literature, consistently reporting that junipers in the Delingha-Dulan area are precipitation proxies and using the site chronologies to reconstruct precipitation over more than a millennium. As noted below, the Dunde ice core location is close to the Dulan junipers and, in fact, the Delingha temperature station is used to calibrate the Dunde ice core. Additional understanding of information from Dulan junipers may shed light on the thorny issues of the Dulan ice core.
Gou et al 2007, cited by twq as supposed evidence for a correlation between Qaidam Basin (Dulan) junipers and temperature, is a new study of a site in the headwaters of the Yellow River rather than the Qaidam Basin and, whatever its merit or lack of merit (and there is much to criticize in the study), hardly stands as evidence one way or the other in respect to Qaidam Basin junipers.
Wang et al 1983 list the location of the 4 cores in the table below, of which they only use the first 3 cores. Core 1 is about 200 km away from cores 2 and 3 and core 4 is another 200 km or so further away. Wang et al 1983 shows the ring widths for each of the cores, indicating a visual similarity between cores 1,2 and 3 to justify the chronology. Core 4 was excluded from the composite due to a different pattern. 3 cores are not considered sufficient to ground a chronology and the continued use of this chronology must surely be regarded as surprising.
Core Rings Lat Long Altitude Faces
1 913 37 00N 98 48E 3670 S
2 935 37 18N 97 12E 3900 S
3 718 37 18N 97 12E 3750 S
4 296 38 42N 99 54E 2600 N
The three cores used in the Wang et al 1983 chronology all come from south-facing slopes of mountains in the Qaidam Basin. More recent studies have sampled similar sites.
Shao et al (Chin Sci Bull 2005, PAGES 2005 and others ) are a series of precipitation reconstructions from juniper sites in the Delingha-Wulan-Dulan area. Shao has some pictures in this online presentation., from which the location map below is taken. Wang et al 1983 Cores 2 and 3 are taken a little to the west of Shao et al site DLH1; Wang et al 1983 Core 1 is taken close to Shao et al site WL2. Shao et al are much larger and more modern collections. Dendrochronologists are always rushing to ”¬Åmove on”¬? – here’s a case where it would be OK for them to move on. I can think of no valid reason for continuing the use of the Wang et al 1983 chronology in place of Shao et al. Or, at a minimum, if Jacoby and Cook want to use Wang et al 1983 as a comparandum, they should at least note the existence of subsequent work in the area.
Left – Location map from Shao et al online presentation. The locations of Shao et al sites are: WL2 37°02′ 98°40′ 3620m SE10°; WL3 36°45′ 98°13′ 3730m; WL4 36°41′ 98°25′ 3700m SW25°; DLH1 37°28′ 97°14′ 3730m NW60°; DLH2 37°28′ 97°13′ 3780m SW20°; DLH3 37°27′ 97°33′ 3920m SW10°; XRD1 35°58′ 98°02′ 3820m SE10° ; XRD2 35°57′ 98°09′ 3840m SE15° ; XRH1 36°21′ 98°22′ 3910m SE70°; XRH2 36°31′ 98°23′ 3830m SE70°. Right – location map from Sheppard et al 2004.
Sheppard et al 2004 was a reconstruction of precipitation since 515 BC obtained from chronologies derived from juniper stands located at 37.0N, 98.5E, 3,800 m elevation near the town of Shenge and 36.0N, 98.0E, 3,800 m elevation near the town of Dulan. The location map for Sheppard et al 2004 is shown in the right panel above. You will notice that the Dunde ice core is located in the top left corner of this location map.
Zhang et al 2003 was a 2326-year reconstruction of spring precipitation derived from juniper sites described as being in the Dulan area (35 50 – 36 30 N, 97 40 – 98 20 E) on south-facing mountain slopes between 3100 m and 3800 m. They do not provide an adequate location map or more precise location information. This is an important study which I will return to because they reported that they used 20 samples from ancient tombs and 68 samples from living trees, of which 55 samples had been collected and examined in a separate study [Kang et al 1997]. Because the Kang et al 1997 chronology was applied in the Yang et al 2002, a composite used in many subsequent Western multiproxy studies as a temperature proxy, this particular network deserves further attention.
Zhang et al [Dendrochronlogia 2007] report on another set of samples taken from living junipers on south-facing mountain slopes northeast of Delingha city at 37 27 N, 97 56E (a bit to the east of DLH3 in the top left location map), ”¬Ågrowing sparsely in open stands at an elevation between 3500-3900m in our study area”. They report the collection of 62 increment cores from 42 trees.
twq has written in to climateaudit, condemning my characterization of Dulan junipers as precipitation proxies and challenged my ability to report on this topic since I have not travelled to Dulan and he has. He cited Gou et al 2007 as authority for the use of Dulan junipers as temperature proxies. I will discuss this separately in a later post. For now, it suffices to that the site studied in Gou et al 2007 is located at 34 45 57N 100 45 44 E in the upper headwaters of the Yellow River. It would not even appear on the location map shown here which covers an area no less than about 400 km by 300 km, although it would appear on a similar scale map to contiguous with this map. Even if the Gou et al 2007 site is a magic thermometer, such analysis does not prove that Qaidam Basin sites are valid temperature proxies. Gou et al 2007 not only does not overturn the interpretations of Shao et al 2005a, 2005b, Sheppard et al 2004, Zhang et al 2003, 2007, it doesn’t even consider them.
While I think that there is much evidence that Qaisam Basin junipers are precipitation proxies, my view on the matter is irrelevant to any arguments made here. All that is relevant to an audit perspective is that qualified specialists – Shao et al; Sheppard et al; Zhang et al – have said so. Even if some subsequent specialist were to come along and prove otherwise, if one is verifying the use of these proxies in multiproxy temperature reconstructions for IPCC 4AR, one has to say that specialists describe them as precipitation proxies and, accordingly, they should not be used in temperature averages.
Given the nearby presence of the Dunde ice core, it’s interesting to look at these reconstructions as precipitation reconstructions and reflect a little on what it might mean for the interpretation of dO18 values in nearby ice cores and I’ll try to do that in a future post.
References: (two of which are inaccessible to me)
Kang, X., Graumlich, L.J., Sheppard, P.R. 1997. A 1,835 year tree-ring chronology and its preliminary analyses in Dulan region, Qinghai. Chinese Science Bulletin 42(13):1122-1124. (also cited as Quatertnary Sciences) [at present inaccessible to me]
SHEPPARD P. R.; TARASOV P. E.; GRAUMLICH L. J.; HEUSSNER K.-U.; WAGNER M.; STERLE H. ; THOMPSON L. G., 2004. Annual precipitation since 515 BC reconstructed from living and fossil juniper growth of northeastern Qinghai Province, China, Climate dynamics, 23,. 869-881 http://www-bprc.mps.ohio-state.edu/Icecore/Abstracts/sheppard_et_al_clim_dyn_2004.pdf
Shao, Xuemei, Lei Huang, Xiuqi Fang, Lili Wang, Junbo Wang, Haifeng Zhu, A Dendroclimatic Study of Qilian Juniper in the northeast Qinghai-Xizang (Tibet) Plateau, http://web.archive.org/web/20031204084631/http://www.igsnrr.ac.cn/files/sxm20020918.pdf downloaded ~2003.
Shao, X.M., Huang, L., Liu, H.B., Liang, E.Y., Fang, X.Q., Wang, L.L., 2005a. Reconstruction of precipitation variation from tree rings in recent 1000 years in Delingha, Qinghai. Science in China (Series D) 34, 145-153.
SHAO, XUEMEI , ERYUAN LIANG, LEI HUANG AND LILY WANG, 2005b. A 1437-year Precipitation History From Qilian Juniper in the Northeastern Qinghai-Tibetan Plateau. PAGES http://www.pages.unibe.ch/products/newsletters/NL2005_2low_res.pdf
Wang Yuxi, Liu Guangyuan, Zhang Xiangong Li Cunfa: 1983, The relationships of tree rings of Qilianshan Juniper and climatic change and glacial activity during the past 1000 years in China, Kexue Tongbao, 28(12):746-750.
Yang, B., X. C. Kang, and Y. F. Shi, 2000. Decadal climatic variations indicated by Dulan tree ring and comparison with other proxy data in China of the last 2000 years, Chinese Geographical Science, 4, 193-201, 2000. [inaccessible to me at present]
Yang Bao, Achim Braeuning, Kathleen R. Johnson, Yafeng Shi, 2002. General characteristics of temperature variation in China during the last two millennia. Geophysical Research Letters 10.1029/2001GL014485
Zhang, Q.-B., Cheng, G., Yao, T., Kang, X. and Huang, J., 2003: A 2,326-year tree-ring record of climate variability on the northeastern Qinghai-Tibetan Plateau. Geophysical Research Letters, Vol. 30(14), 1739, doi: 10.1029/2003GL017425. http://trl.ibcas.ac.cn/download/Zhangqb.Geophysical_Research_Letters.2003.pdf
Zhang et al 2007 A millennium-long tree-ring chronology of Sabina przewalskii on northeastern Qinghai-Tibetan Plateau, Dendrochronlogia 24 http://trl.ibcas.ac.cn/download/Zhangqb.2007.Dendrochronologia.pdf