A new paper in Nature by Tingley and Huybers h/t WUWT.
In keeping with the total and complete stubbornness of the paleoclimate community, they use the most famous series of Mann et al 2008: the contaminated Korttajarvi sediments, the problems with which are well known in skeptic blogs and which were reported in a comment at PNAS by Ross and I at the time. The original author, Mia Tiljander, warned against use of the modern portion of this data, as the sediments had been contaminated by modern bridgebuilding and farming. Although the defects of this series as a proxy are well known to readers of “skeptical” blogs, peer reviewers at Nature were obviously untroubled by the inclusion of this proxy in a temperature reconstruction.
For the Korttajarvi Lake record, we use the organic layer thickness, as the original publication indicates that a thicker organic layer “probably indicates a warmer summer and a relatively long growing season” [57- Boreas].
However, they didn’t mention the following:
This recent increase in thickness is due to the clay-rich varves caused by intensive cultivation in the late 20th century.
In the 20th century the Lake Korttaja¨rvi record was strongly affected by human activities. The average varve thickness is 1.2 mm from AD 1900 to 1929, 1.9 mm from AD 1930 to 1962 and 3.5 mm from AD 1963 to 1985. There are two exceptionally thick clay-silt layers caused by man. The thick layer of AD 1930 resulted from peat ditching and forest clearance (information from a local farmer in 1999) and the thick layer of AD 1967 originated due to the rebuilding of the bridge in the vicinity of the lake’s southern corner (information from the Finnish Road Administration). Varves since AD 1963 towards the present time thicken because of the higher water content in the top of the sediment column. However, the gradually increasing varve thickness during the whole 20th century probably originates from the accelerating agricultural use of the area around the lake.
All of this was discussed ad nauseam following Mann et al 2008, though Mann stubbornly refused to concede anything. Kaufman et al 2009 also used the data and, on the advice of Overpeck, conceded the point and issued a corrigendum. Raymond Bradley was a coauthor of both papers and more or less simultaneously took the position that a corrigendum was required and not required.
I’m sure that we’ll be told that their use of contaminated Korttajarvi data doesn’t “matter” – nothing ever seems to. But why use it?
Steve Update Apr 11:
For R users, I’ve collated the Tingley proxies into a time series R-matrix called proxy.tab at http://www.climateaudit.info/data/multiproxy/tingley_2013 and their metadata as info_tingley.csv. A simple average of all the Tingley proxies is shown below. It has a divergence problem because the majority of proxies are MXD proxies.
Their Figure S34 top panel shows a reconstruction from MXD proxies along. The reconstruction is very similar to an MXD average,as shown below.
Figure ^. Tingley and Huybers S34 top panel, showing one variation of their proxy-only reconstructions (MXD), with average of MXD proxies (green) for comparison.
Tingley has provided an exemplary archive. It requires a little collation. R users who wish to skip their own collation may use my collation as follows:
download.file("http://www.climateaudit.info/data/multiproxy/tingley_2013/proxy.tab","d:/temp/temp",mode="wb") load("d:/temp/temp") tsp(proxy) #1400 2005 info=read.csv("http://www.climateaudit.info/data/multiproxy/tingley_2013/info_tingley.csv") dim(info) # 125 11 annual=ts(apply(scale(proxy),1,mean,na.rm=T),start=1400) count=ts(apply(!is.na(proxy),1,sum),start=1400) max(time(count)[count>20]) #1992 #png(file="d:/climate/images/multiproxy/tingley_avg.png",w=680,h=480) plot.ts( window(annual, end=max(time(count)[count>20]) ),ylab="SD Units") title("Average of Normalized Tingley Proxies") abline(h=0,lty=3) #dev.off()