Jones, P.D., K.R. Briffa, T.P. Barnett, and S.F.B. Tett (1998). "High-resolution Palaeoclimatic Records for the last Millennium: Interpretation, Integration and Comparison with General Circulation Model Control-run Temperatures". The Holocene 8: 455-471. DOI:10.1191/095968398667194956.
Abstract
Palaeoclimatology provides our only means of assessing climatic variations before the beginning of instrumental records. The various proxy variables used, however, have a number of limitations which must be adequately addressed and understood. Besides their obvious spatial and seasonal limitations, different proxies are also potentially limited in their ability to represent climatic variations over a range of different timescales. Simple correlations with instrumental data over the period since ad 1881 give some guide to which are the better proxies, indicating that coral- and ice-core-based reconstructions are poorer than tree-ring and historical ones. However, the quality of many proxy time series can deteriorate during earlier times. Suggestions are made for assessing proxy quality over longer periods than the last century by intercomparing neighbouring proxies and, by comparisons with less temporally resolved proxies such as borehole temperatures. We have averaged 17 temperature reconstructions (representing various seasons of the year), all extending back at least to the mid-seventeenth century, to form two annually resolved hemispheric series (NH10 and SH7). Over the 1901–91 period, NH10 has 36% variance in common with average NH summer (June to August) temperatures and 70% on decadal timescales. SH7 has 16% variance in common with average SH summer (December to February) temperatures and 49% on decadal timescales, markedly poorer than the reconstructed NH series. The coldest year of the millennium over the NH is ad 1601, the coldest decade 1691–1700 and the seventeenth is the coldest century. A Principal Components Analysis (PCA) is performed on yearly values for the 17 reconstructions over the period ad 1660–1970. The correlation between PC1 and NH10 is 0.92, even though PC1 explains only 13.6% of the total variance of all 17 series. Similar PCA is performed on thousand-year-long General Circulation Model (GCM) data from the Geophysical Fluid Dynamics Laboratory (GFDL) and the Hadley Centre (HADCM2), sampling these for the same locations and seasons as the proxy data. For GFDL, the correlation between its PC1 and its NH10 is 0.89, while for HADCM2 the PCs group markedly differently. Cross-spectral analyses are performed on the proxy data and the GFDL model data at two different frequency bands (0.02 and 0.03 cycles per year). Both analyses suggest that there is no large-scale coherency in the series on these timescales. This implies that if the proxy data are meaningful, it should be relatively straightforward to detect a coherent near-global anthropogenic signal in surface temperature data.
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Jones et al 1998, which currently (12/8/07) includes:
The Briffa-Osborn Variance Adjustment Juckes and the Divergence Problem Polar Urals Update and Jones et al 1998 . SM demonstrates that the J98 reconstruction is not robust, when replacing one proxy series with an update used in a later multiproxy study. Making Hockey Sticks the Jones Way , a key discussion of data manipulation. More O.B. Confidential Polar Urals Spaghetti Graph , peripheral to Jones et al (1998). Polar Urals and Yamal Mean Ring Widths Polar Urals: Briffa versus Esper Polar Urals “Grass Plot” , grass plots and super-trees, novel analyses by Steve McIntyre (SM), see TCO, posts #1 & 12. Jones et al (1998): Verifying Reported Gridcell Correlations Jones et al (1998): Variance Adjustment Jones et al. (1998): The Proxies . Jones et al. did not archive their proxy set. SM requested this information from Jones; he refused to supply the data. Jones et al (1998): Confidence Intervals . They are almost worthless, and typical of dendro statistical cluelessness. See Willis Eschenbach, Post #10. More on Urals and Tornetrask Updated Polar Urals Data Noise in Multiproxy Studies Noise in Jones et al (1998) : "there is virtually no "signal" in this set of proxies..." Jones et al (1998): Gridcell Correlations , opaque to non-specialists. U.S. Climate Change Science Program Workshop Plots of Gaspe and Polar Urals Data Polar Urals: Shiyatov’s Finnish Academy Article Tornetrask Regressions Polar Urals #4 “Heartrot Bias”? Polar Urals #3 Crossdating Polar Urals #2 Broken Core Polar Urals #1 “Modern Sample Bias”, RCS and Briffa’s “Adjustment” Tornetrask #4 Confidence Intervals Tornetrask #3 A Truncated Diagram Tornetrask #2 Altitude at Briffa’s Polar Urals Briffa’s Tornetrask Reconstruction “SPAGHETTI DIAGRAMS” — this has the Jones et al. (1998) reconstruction compared to other studies.
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