Category Archives: Mann et al 2008

More on Voodoo Correlations

Mann said: Although 484 (~40%) pass the temperature screening process over the full (1850–1995) calibration interval, one would expect that no more than ~150 (13%) of the proxy series would pass the screening procedure described above by chance alone. Reader DC said: Of the 484 proxies passing the 1850-1995 significance test, 342 also passed both […]

More Changes at the Mann 2008 SI

Mannian confidence intervals have always been a mystery with MBH99 confidence interval methodology remaining an intractable mystery that has defeated all reverse engineering (and engineering) efforts by UC, Jean S and myself to date (though we haven’t picked up this file for a while.) I was very interested to see how Mann 2008 calculated confidence […]

Smoothing Dongge

Mann reported a “significant” correlation of -0.5481829 between Dongge dO18 and gridcell temperature. Today I will report on exactly how Mann calculated this “significant” correlation. In keeping with recent requests, I will refrain from making any comments on this procedure, in the confident expectation that my critics will provide some commentary on what they think […]

Mann et al 2008 – Another Error Notice

In previous posts, I’ve observed my inability to replicate Mann’s verification statistics, the source code for which was not archived despite representations to the contrary in the original article. Mann has issued another uninformative correction notice (bearing the date Dec 1, 2008) which states: UPDATE 1 December 2008: Supplementary Figure S8a had a small error […]

Five Monsoon O18 Series

Jud Partin observed yesterday that a “fantastic new record” had been recently (early Nov 2008) published from Wanxiang, China. Zhang et al report that their new record is “broadly similar” to the reconstructions of Esper, Mann and Jones 2003 and Moberg as follows: The Wanxiang record, with a d18O range of ~1.3 per mil (‰) […]

All-Proxy CPS

As first fruits of my Mannian CPS emulation, I did a quick sensitivity to see what results looked for the AD800 network without the Tiljander upside-down sediments. I did the run with all proxies except Tiljander sediments as I first cut, since Mannian screening of series that are supposed to be proxies is not a […]

Emulating Mannian CPS

I’ve spent an inordinate amount of time working up a practical emulation of Mannian CPS and have uploaded a function to do this. While Mann has made a decent effort to archive code and intermediates, as others have noted, the code itself is chaotic and hard to figure out. Added to this are the “stupid […]

Calibrating Tropical Speleothems

Readers have inquired recently about how tropical speleothems are calibrated to temperature. Judd Partin, Kim Cobb (both of Georgia Tech) and associates wrote an excellent article last year (Cobb et al, EPSL 2007) on detailed O18 observations near a Borneo speleothem about which they had published. They introduced the article with the following observation that […]

Gavin Schmidt and "Uniquely" Oriented Speleothems

In our examination of the new Mann proxies, there is a notable increase in the prevalence of speleothem proxies in the MWP network. Craig Loehle used a couple of speleothem proxies in his reconstruction. One was a grey-scale series from Holmgren’s Cold Air Cave, South Africa. Not to be outdone, Mann et al used two […]

Mann and Perfect Reconstructions

I finally turned over a few stones in Mann’s EIV reconstructions, little suspecting the perfection that awaited me in the cave using the simple and unassuming alter ego shglfulihad_smxx. The figure below compares the SH reconstruction to the smoothed (SH) iHAD instrumental version. From the frail instruments of speleothems, bristlecone ring widths and upside-down sediments, […]